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What is the main cause of HIV-1 infection in children?
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BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
| 630
|
What is the main cause of HIV-1 infection in children?
|
BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
|
The samples used in the present study were from mother-child pairs randomly assigned to the placebo group of the ZVITAMBO project. Antiretroviral prophylaxis for HIV-1-positive antenatal women was not available in the Harare public-sector during ZVITAMBO patient recruitment. The samples were consecutively drawn from two groups: 97 HIV-1-positive mother/HIV-1-positive child pairs and 100 HIV-1-positive mother/HIV-negative child pairs. Mother's serological status was determined by ELISA and confirmed by Western Blot. Infants were considered to be infected if they were HIV-1 seropositive at 18 months or older and had two or more positive HIV-1-DNA polymerase chain reaction PCR results at earlier ages. 100 infants were considered to be uninfected as they were ELISA negative at 18 months or older and had two DNA PCR negative results from samples collected at a younger age.
| 630
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What is the main cause of HIV-1 infection in children?
|
BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
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H1 31% and H3 11% were the most frequent haplotypes observed Figure 1 . Being homozygous for the H1 haplotype was associated with increased risk of both IU OR: 4.42, P = 0.022 and PP OR: 7.31, P = 0.016 HIV-1 transmission Table 2 . Infants harbouring two copy combinations of H1 and/ or H3 haplotypes H1-H1, H1-H3 or H3-H3 had increased risk of IU OR: 3.42, P = 0.007 and IP OR: 5.71, P = 0.025 but not PP P = 0.098 HIV-1 infection compared to infant noncarriers Table 2 . The latter associations remained significant after adjustment was made for the maternal viral load for both IU OR: 3.57, 95% CI = 1.30-9.82, P = 0.013 and IP OR: 5.71, 95% CI = 1.40-23.3, P = 0.025 HIV-1 transmission. The H1 and H3 haplotypes share a cluster of mutations p-198A, int2-391C, int2-180A, ex4RPT, int5+7C Figure 1 . Of these, the p-198A and int2-180A variants were significantly associated with MTCT of HIV-1 Table S2 .
| 630
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What is the main cause of HIV-1 infection in children?
|
BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
|
The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
| 630
|
What is the main cause of HIV-1 infection in children?
|
BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
|
Infants were considered to be infected if they were HIV-1 seropositive at 18 months or older and had two or more positive HIV-1-DNA polymerase chain reaction PCR results at earlier ages. 100 infants were considered to be uninfected as they were ELISA negative at 18 months or older and had two DNA PCR negative results from samples collected at a younger age. Of the 97 HIV-1-infected infants, 57 were infected IU, 11 were infected IP, and 17 were infected PP as determined by PCR analyses of blood samples collected at birth, 6 weeks, 3 and 6 months of age and according to the following definitions adapted from Bryson and colleagues . Briefly, infants who were DNA PCR positive at birth were infected IU. Infants with negative PCR results from sample obtained at birth but who become positive by 6 weeks of age were infected IP. Infants with negative PCR results at birth and 6 weeks of age but who subsequently became DNA PCR positive were considered to be infected during the PP period.
| 630
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What plays the crucial role in the Mother to Child Transmission of HIV-1 and what increases the risk
|
The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
|
Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
| 630
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What plays the crucial role in the Mother to Child Transmission of HIV-1 and what increases the risk
|
The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
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Such process called microtransfusion has been proposed in regards to the results obtain in a Malawian cohort. Kweik and colleagues found a significant association between levels of maternal DNA in umbilical cord blood and IP transmission of HIV-1 suggesting that passage of maternal infected cells through the placenta is likely to occur during delivery . Thus, in a similar fashion as suggested earlier for IU transmission, the relatively lower level of DC-SIGNR in the placenta of homozygous infants harbouring the int2-180A variant could promote HIV-1 binding to CCR5 receptor on endothelial cells affecting the placental barrier integrity and facilitating the passage of maternal infected cells in foetal circulation during delivery. Beside DC-SIGNR, other HIV-1 receptors are known to influence MTCT of HIV-1 reviewed in . Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans .
| 630
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What plays the crucial role in the Mother to Child Transmission of HIV-1 and what increases the risk
|
The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
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It is thus possible that reduced expression of DC-SIGNR, particularly the membranebound isoforms, on placental capillary endothelial cells might favour HIV-1 binding to CCR5 receptor, instead of DC-SIGNR receptor, facilitating the migration of maternal HIV-1-infected cells across the placental barrier resulting in IU transmission of HIV-1. The int2-180A variant contained in the H1 and H3 haplotypes was associated with IP transmission suggesting that DC-SIGNR also affect transmission of HIV-1 during delivery. Little is known about the mechanisms underlying transmission of HIV-1 during delivery. Passage through the birth canal could potentially expose infants through a mucosal portal entry presumably ophthalmic, skin, or gastrointestinal , whereas placental insult during delivery physical or inflammatory may enhance transplacental passage of maternal HIV-1-infected cells into foetal circulation . Such process called microtransfusion has been proposed in regards to the results obtain in a Malawian cohort. Kweik and colleagues found a significant association between levels of maternal DNA in umbilical cord blood and IP transmission of HIV-1 suggesting that passage of maternal infected cells through the placenta is likely to occur during delivery .
| 630
|
What plays the crucial role in the Mother to Child Transmission of HIV-1 and what increases the risk
|
The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
|
BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
| 630
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What plays the crucial role in the Mother to Child Transmission of HIV-1 and what increases the risk
|
The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
| 630
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How many children were infected by HIV-1 in 2008-2009, worldwide?
|
Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
|
Infants were considered to be infected if they were HIV-1 seropositive at 18 months or older and had two or more positive HIV-1-DNA polymerase chain reaction PCR results at earlier ages. 100 infants were considered to be uninfected as they were ELISA negative at 18 months or older and had two DNA PCR negative results from samples collected at a younger age. Of the 97 HIV-1-infected infants, 57 were infected IU, 11 were infected IP, and 17 were infected PP as determined by PCR analyses of blood samples collected at birth, 6 weeks, 3 and 6 months of age and according to the following definitions adapted from Bryson and colleagues . Briefly, infants who were DNA PCR positive at birth were infected IU. Infants with negative PCR results from sample obtained at birth but who become positive by 6 weeks of age were infected IP. Infants with negative PCR results at birth and 6 weeks of age but who subsequently became DNA PCR positive were considered to be infected during the PP period.
| 630
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How many children were infected by HIV-1 in 2008-2009, worldwide?
|
Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
|
The samples used in the present study were from mother-child pairs randomly assigned to the placebo group of the ZVITAMBO project. Antiretroviral prophylaxis for HIV-1-positive antenatal women was not available in the Harare public-sector during ZVITAMBO patient recruitment. The samples were consecutively drawn from two groups: 97 HIV-1-positive mother/HIV-1-positive child pairs and 100 HIV-1-positive mother/HIV-negative child pairs. Mother's serological status was determined by ELISA and confirmed by Western Blot. Infants were considered to be infected if they were HIV-1 seropositive at 18 months or older and had two or more positive HIV-1-DNA polymerase chain reaction PCR results at earlier ages. 100 infants were considered to be uninfected as they were ELISA negative at 18 months or older and had two DNA PCR negative results from samples collected at a younger age.
| 630
|
How many children were infected by HIV-1 in 2008-2009, worldwide?
|
Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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Written informed consent was obtained from all mothers who participated in the study and the ZVITAMBO trial and the investigation reported in this paper were approved by The We carried out an association study of DC-SIGNR polymorphism in 197 infants born to untreated HIV-1-infected mothers recruited in Harare, Zimbabwe. Among them, 97 infants were HIV-1-infected and 100 infants remained uninfected. Of the 97 HIV-1-infected infants, 57 were infected IU, 11 were infected IP, and 17 were infected PP. Timing of infection was not determined for 12 HIV-1-infected infants. Baseline characteristics of mothers and infants are presented in Table 1 . Maternal age and CD4 cell count, child sex, mode of delivery, duration of membrane rupture and gestational age were similar among all groups.
| 630
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How many children were infected by HIV-1 in 2008-2009, worldwide?
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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Baseline characteristics of mothers and infants are presented in Table 1 . Maternal age and CD4 cell count, child sex, mode of delivery, duration of membrane rupture and gestational age were similar among all groups. However, maternal viral load .29 000 copies/ml was associated with increased risk in both IU and PP with odds ratios OR of 3.64 95% CI = 1.82-7.31, P = 0.0002 and 4.45 95% CI = 1.50-13.2, P = 0.0045 for HIV-1 transmission, respectively. Fifteen haplotype-tagged SNPs htSNPs corresponding to the 15 major DC-SIGNR haplotypes Figure 1 described among Zimbabweans were genotyped in our study samples Tables S2 and S3 . H1 31% and H3 11% were the most frequent haplotypes observed Figure 1 . Being homozygous for the H1 haplotype was associated with increased risk of both IU OR: 4.42, P = 0.022 and PP OR: 7.31, P = 0.016 HIV-1 transmission Table 2 .
| 630
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How many children were infected by HIV-1 in 2008-2009, worldwide?
|
Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
|
H1 31% and H3 11% were the most frequent haplotypes observed Figure 1 . Being homozygous for the H1 haplotype was associated with increased risk of both IU OR: 4.42, P = 0.022 and PP OR: 7.31, P = 0.016 HIV-1 transmission Table 2 . Infants harbouring two copy combinations of H1 and/ or H3 haplotypes H1-H1, H1-H3 or H3-H3 had increased risk of IU OR: 3.42, P = 0.007 and IP OR: 5.71, P = 0.025 but not PP P = 0.098 HIV-1 infection compared to infant noncarriers Table 2 . The latter associations remained significant after adjustment was made for the maternal viral load for both IU OR: 3.57, 95% CI = 1.30-9.82, P = 0.013 and IP OR: 5.71, 95% CI = 1.40-23.3, P = 0.025 HIV-1 transmission. The H1 and H3 haplotypes share a cluster of mutations p-198A, int2-391C, int2-180A, ex4RPT, int5+7C Figure 1 . Of these, the p-198A and int2-180A variants were significantly associated with MTCT of HIV-1 Table S2 .
| 630
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What is the role of C-C Motif Chemokine Ligand 3 Like 1 (CCL3L1) in mother to child transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
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What is the role of C-C Motif Chemokine Ligand 3 Like 1 (CCL3L1) in mother to child transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
| 630
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What is the role of C-C Motif Chemokine Ligand 3 Like 1 (CCL3L1) in mother to child transmission of HIV-1?
|
Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
| 630
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What is the role of C-C Motif Chemokine Ligand 3 Like 1 (CCL3L1) in mother to child transmission of HIV-1?
|
Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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To date, most studies have focused on the potential role of DC-SIGNR in trans infection of HIV-1 in vitro . However, the multiple mechanisms involved in trans infection and redundancy among C-type lectin functions make it difficult to determine the actual participation of DC-SIGNR in this mode of infection in vivo . The strong correlation we observed between MTCT of HIV-1 and DC-SIGNR genetic variants producing low levels of DC-SIGNR in the placenta suggested that mechanisms other than DC-SIGNR-mediated trans infection might operate during vertical transmission of HIV-1. For example, DC-SIGNR has also been shown to function as a HIV-1 antigen-capturing receptor . Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response .
| 630
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What is the role of C-C Motif Chemokine Ligand 3 Like 1 (CCL3L1) in mother to child transmission of HIV-1?
|
Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response . The HIV-1 coreceptor CCR5, but not CD4, is co-expressed with DC-SIGNR on placental and blood-brain barrier BBB endothelial cells . HIV-1 gp120 binding to CCR5 receptor on endothelial cells compromises BBB integrity and enhances monocytes adhesion and transmigration across the BBB . It is thus possible that reduced expression of DC-SIGNR, particularly the membranebound isoforms, on placental capillary endothelial cells might favour HIV-1 binding to CCR5 receptor, instead of DC-SIGNR receptor, facilitating the migration of maternal HIV-1-infected cells across the placental barrier resulting in IU transmission of HIV-1. The int2-180A variant contained in the H1 and H3 haplotypes was associated with IP transmission suggesting that DC-SIGNR also affect transmission of HIV-1 during delivery.
| 630
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What is DC-GENR and where is it expressed?
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms . It has been proposed that interaction between DC-SIGNR and HIV-1 might enhance viral transfer to other susceptible cell types but DC-SIGNR can also internalize and mediate proteasome-dependant degradation of viruses that may differently affect the outcome of infection. Given the presence of DC-SIGNR at the maternal-fetal interface and its interaction with HIV-1, we hypothesized that it could influence MTCT of HIV-1. To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of HIV-infected mothers and their infants recruited in Zimbabwe, and identified specific DC-SIGNR variants associated with increased risks of HIV transmission. We further characterized the functional impact of these genetic variants on DC-SIGNR expression and show that they affect both the level and type of DC-SIGNR transcripts produced in the placenta.
| 630
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What is DC-GENR and where is it expressed?
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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Quantitative expression of DC-SIGNR isoforms 1,5 mg of placental RNA was reverse transcribed using 2.5 mM of Oligo dT 20 and Expand RT in 20 ml volume according to the manufacturer Roche Applied Science . 15 ng of total cDNA in a final volume of 20 ml was used to perform quantitative real-time PCR using Universal Express SYBR GreenER qPCR Supermix Invitrogen on a Rotor Gene Realtime Rotary Analyser Corbett Life Science, Sydney, Australia . Samples from 2 subjects in each group were used because RNA quality of others was not suitable for a qRT-PCR analysis. Amplification of all DC-SIGNR isoforms was performed using an exon 5 specific primer pair Table S1 . Membrane-bound isoforms were amplified using primers specific for exon 3, corresponding to the common trans-membrane domain of DC-SIGNR. Primers were targeted to the exon-exon junction and RNA extracts were treated with DNase Fermantas International inc, Burlington, ON, Canada to avoid amplification of contaminant DNA.
| 630
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What is DC-GENR and where is it expressed?
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced. Sequenced were analysed according to NCBI reference sequence NM_014257. CT; cytoplasmic tail, TM; trans-membrane domain; WT; wild-type Found at: .1371/journal.pone.0007211.s004 Figure S2 Effect of DC-SIGNR promoter variant on transcriptional activity in luciferase reporter assay in vitro in transfected HeLa cells. Relative luciferase expression from pGL2-Basic, parental vector without promoter. Expression DC-SIGNR promoter constructs, spanning p-577C variant or p-323A variant were calculated relatively to this value. Data are presented in mean values6S.E.M of three independent experiments performed in triplicate.
| 630
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What is DC-GENR and where is it expressed?
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
| 630
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What is DC-GENR and where is it expressed?
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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These htSNPs were genotyped in the 197 infants by direct PCR sequencing analysis as we have described previously . The DC-SIGNR exon 4 repeat region genotype was determined by PCR amplification followed by migration in 1.5% agarose gels . DNA sequences in the promoter region were analysed with the TESS interface for putative transcription factors binding sites using the TRANSFAC database. Luciferase reporter assays using pGL2-Basic vector were performed in order to investigate the functional effect of mutations on DC-SIGNR promoter activity. Genomic DNA from subjects homozygous for the promoter variants and WT was amplified from nucleotide position 2715 to 21 and cloned between the BglII and HindIII multiple cloning sites in the pGL2-Basic vector which harbours a reporter firefly luciferase gene downstream Invitrogen Canada inc, Burlington, Canada . All recombinants clones were verified by DNA sequencing.
| 630
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What is DC-GENR and where is it expressed?
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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Full-term placenta samples were not available for the current study and the expression assays were performed on first-term placental tissues. A previous study looking at DC-SIGNR placental isoforms repertoire in full-term placenta samples demonstrated similar diversity of DC-SIGNR transcripts as in the first-term placental tissues studied herein . However, since levels of DC-SIGNR expression have never been compared between the different terms of pregnancy, it is not known whether DC-SIGNR expression varies during the course of pregnancy. Nevertheless, it is reasonable to assume that the inter-individual differences in both DC-SIGNR isoform repertoire and transcript levels observed between the H1 and WT homozygous infants would be reflected throughout the pregnancy. To date, most studies have focused on the potential role of DC-SIGNR in trans infection of HIV-1 in vitro . However, the multiple mechanisms involved in trans infection and redundancy among C-type lectin functions make it difficult to determine the actual participation of DC-SIGNR in this mode of infection in vivo .
| 630
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How does the presence of DC-SIGNR affect the MTCT of HIV-1?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms . It has been proposed that interaction between DC-SIGNR and HIV-1 might enhance viral transfer to other susceptible cell types but DC-SIGNR can also internalize and mediate proteasome-dependant degradation of viruses that may differently affect the outcome of infection. Given the presence of DC-SIGNR at the maternal-fetal interface and its interaction with HIV-1, we hypothesized that it could influence MTCT of HIV-1. To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of HIV-infected mothers and their infants recruited in Zimbabwe, and identified specific DC-SIGNR variants associated with increased risks of HIV transmission. We further characterized the functional impact of these genetic variants on DC-SIGNR expression and show that they affect both the level and type of DC-SIGNR transcripts produced in the placenta.
| 630
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How does the presence of DC-SIGNR affect the MTCT of HIV-1?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
| 630
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How does the presence of DC-SIGNR affect the MTCT of HIV-1?
|
Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
|
To date, most studies have focused on the potential role of DC-SIGNR in trans infection of HIV-1 in vitro . However, the multiple mechanisms involved in trans infection and redundancy among C-type lectin functions make it difficult to determine the actual participation of DC-SIGNR in this mode of infection in vivo . The strong correlation we observed between MTCT of HIV-1 and DC-SIGNR genetic variants producing low levels of DC-SIGNR in the placenta suggested that mechanisms other than DC-SIGNR-mediated trans infection might operate during vertical transmission of HIV-1. For example, DC-SIGNR has also been shown to function as a HIV-1 antigen-capturing receptor . Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response .
| 630
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How does the presence of DC-SIGNR affect the MTCT of HIV-1?
|
Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
| 630
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How does the presence of DC-SIGNR affect the MTCT of HIV-1?
|
Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
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Why do low levels of DC-SIGNR enhance Mother to Child Transmission of HIV-1?
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
| 630
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Why do low levels of DC-SIGNR enhance Mother to Child Transmission of HIV-1?
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
| 630
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Why do low levels of DC-SIGNR enhance Mother to Child Transmission of HIV-1?
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
| 630
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Why do low levels of DC-SIGNR enhance Mother to Child Transmission of HIV-1?
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response . The HIV-1 coreceptor CCR5, but not CD4, is co-expressed with DC-SIGNR on placental and blood-brain barrier BBB endothelial cells . HIV-1 gp120 binding to CCR5 receptor on endothelial cells compromises BBB integrity and enhances monocytes adhesion and transmigration across the BBB . It is thus possible that reduced expression of DC-SIGNR, particularly the membranebound isoforms, on placental capillary endothelial cells might favour HIV-1 binding to CCR5 receptor, instead of DC-SIGNR receptor, facilitating the migration of maternal HIV-1-infected cells across the placental barrier resulting in IU transmission of HIV-1. The int2-180A variant contained in the H1 and H3 haplotypes was associated with IP transmission suggesting that DC-SIGNR also affect transmission of HIV-1 during delivery.
| 630
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Why do low levels of DC-SIGNR enhance Mother to Child Transmission of HIV-1?
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms . It has been proposed that interaction between DC-SIGNR and HIV-1 might enhance viral transfer to other susceptible cell types but DC-SIGNR can also internalize and mediate proteasome-dependant degradation of viruses that may differently affect the outcome of infection. Given the presence of DC-SIGNR at the maternal-fetal interface and its interaction with HIV-1, we hypothesized that it could influence MTCT of HIV-1. To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of HIV-infected mothers and their infants recruited in Zimbabwe, and identified specific DC-SIGNR variants associated with increased risks of HIV transmission. We further characterized the functional impact of these genetic variants on DC-SIGNR expression and show that they affect both the level and type of DC-SIGNR transcripts produced in the placenta.
| 630
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What is the percentage of Mother to Child Transmission of HIV-1, when there is no intervention?
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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The samples used in the present study were from mother-child pairs randomly assigned to the placebo group of the ZVITAMBO project. Antiretroviral prophylaxis for HIV-1-positive antenatal women was not available in the Harare public-sector during ZVITAMBO patient recruitment. The samples were consecutively drawn from two groups: 97 HIV-1-positive mother/HIV-1-positive child pairs and 100 HIV-1-positive mother/HIV-negative child pairs. Mother's serological status was determined by ELISA and confirmed by Western Blot. Infants were considered to be infected if they were HIV-1 seropositive at 18 months or older and had two or more positive HIV-1-DNA polymerase chain reaction PCR results at earlier ages. 100 infants were considered to be uninfected as they were ELISA negative at 18 months or older and had two DNA PCR negative results from samples collected at a younger age.
| 630
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What is the percentage of Mother to Child Transmission of HIV-1, when there is no intervention?
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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Baseline characteristics of mothers and infants are presented in Table 1 . Maternal age and CD4 cell count, child sex, mode of delivery, duration of membrane rupture and gestational age were similar among all groups. However, maternal viral load .29 000 copies/ml was associated with increased risk in both IU and PP with odds ratios OR of 3.64 95% CI = 1.82-7.31, P = 0.0002 and 4.45 95% CI = 1.50-13.2, P = 0.0045 for HIV-1 transmission, respectively. Fifteen haplotype-tagged SNPs htSNPs corresponding to the 15 major DC-SIGNR haplotypes Figure 1 described among Zimbabweans were genotyped in our study samples Tables S2 and S3 . H1 31% and H3 11% were the most frequent haplotypes observed Figure 1 . Being homozygous for the H1 haplotype was associated with increased risk of both IU OR: 4.42, P = 0.022 and PP OR: 7.31, P = 0.016 HIV-1 transmission Table 2 .
| 630
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What is the percentage of Mother to Child Transmission of HIV-1, when there is no intervention?
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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H1 31% and H3 11% were the most frequent haplotypes observed Figure 1 . Being homozygous for the H1 haplotype was associated with increased risk of both IU OR: 4.42, P = 0.022 and PP OR: 7.31, P = 0.016 HIV-1 transmission Table 2 . Infants harbouring two copy combinations of H1 and/ or H3 haplotypes H1-H1, H1-H3 or H3-H3 had increased risk of IU OR: 3.42, P = 0.007 and IP OR: 5.71, P = 0.025 but not PP P = 0.098 HIV-1 infection compared to infant noncarriers Table 2 . The latter associations remained significant after adjustment was made for the maternal viral load for both IU OR: 3.57, 95% CI = 1.30-9.82, P = 0.013 and IP OR: 5.71, 95% CI = 1.40-23.3, P = 0.025 HIV-1 transmission. The H1 and H3 haplotypes share a cluster of mutations p-198A, int2-391C, int2-180A, ex4RPT, int5+7C Figure 1 . Of these, the p-198A and int2-180A variants were significantly associated with MTCT of HIV-1 Table S2 .
| 630
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What is the percentage of Mother to Child Transmission of HIV-1, when there is no intervention?
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers P = 0.011 . CONCLUSION: These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission. Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa.
| 630
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What is the percentage of Mother to Child Transmission of HIV-1, when there is no intervention?
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Text: Without specific interventions, the rate of HIV-1 mother-tochild transmission MTCT is approximately 15-45% . UNAIDS estimates that last year alone, more than 400,000 children were infected worldwide, mostly through MTCT and 90% of them lived in sub-Saharan Africa. In the most heavilyaffected countries, such as Zimbabwe, HIV-1 is responsible for one third of all deaths among children under the age of five. MTCT of HIV-1 can occur during pregnancy in utero, IU , delivery intrapartum, IP or breastfeeding postpartum, PP . High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy.
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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Does C-C chemokine receptor type 5 (CCR5) affect the transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response . The HIV-1 coreceptor CCR5, but not CD4, is co-expressed with DC-SIGNR on placental and blood-brain barrier BBB endothelial cells . HIV-1 gp120 binding to CCR5 receptor on endothelial cells compromises BBB integrity and enhances monocytes adhesion and transmigration across the BBB . It is thus possible that reduced expression of DC-SIGNR, particularly the membranebound isoforms, on placental capillary endothelial cells might favour HIV-1 binding to CCR5 receptor, instead of DC-SIGNR receptor, facilitating the migration of maternal HIV-1-infected cells across the placental barrier resulting in IU transmission of HIV-1. The int2-180A variant contained in the H1 and H3 haplotypes was associated with IP transmission suggesting that DC-SIGNR also affect transmission of HIV-1 during delivery.
| 630
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Does C-C chemokine receptor type 5 (CCR5) affect the transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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To date, most studies have focused on the potential role of DC-SIGNR in trans infection of HIV-1 in vitro . However, the multiple mechanisms involved in trans infection and redundancy among C-type lectin functions make it difficult to determine the actual participation of DC-SIGNR in this mode of infection in vivo . The strong correlation we observed between MTCT of HIV-1 and DC-SIGNR genetic variants producing low levels of DC-SIGNR in the placenta suggested that mechanisms other than DC-SIGNR-mediated trans infection might operate during vertical transmission of HIV-1. For example, DC-SIGNR has also been shown to function as a HIV-1 antigen-capturing receptor . Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response .
| 630
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Does C-C chemokine receptor type 5 (CCR5) affect the transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
| 630
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Does C-C chemokine receptor type 5 (CCR5) affect the transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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Such process called microtransfusion has been proposed in regards to the results obtain in a Malawian cohort. Kweik and colleagues found a significant association between levels of maternal DNA in umbilical cord blood and IP transmission of HIV-1 suggesting that passage of maternal infected cells through the placenta is likely to occur during delivery . Thus, in a similar fashion as suggested earlier for IU transmission, the relatively lower level of DC-SIGNR in the placenta of homozygous infants harbouring the int2-180A variant could promote HIV-1 binding to CCR5 receptor on endothelial cells affecting the placental barrier integrity and facilitating the passage of maternal infected cells in foetal circulation during delivery. Beside DC-SIGNR, other HIV-1 receptors are known to influence MTCT of HIV-1 reviewed in . Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans .
| 630
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Does C-C chemokine receptor type 5 (CCR5) affect the transmission of HIV-1?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
| 630
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How does Mannanose Binding Lectin (MBL) affect elimination of HIV-1 pathogen?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
| 630
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How does Mannanose Binding Lectin (MBL) affect elimination of HIV-1 pathogen?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
|
To date, most studies have focused on the potential role of DC-SIGNR in trans infection of HIV-1 in vitro . However, the multiple mechanisms involved in trans infection and redundancy among C-type lectin functions make it difficult to determine the actual participation of DC-SIGNR in this mode of infection in vivo . The strong correlation we observed between MTCT of HIV-1 and DC-SIGNR genetic variants producing low levels of DC-SIGNR in the placenta suggested that mechanisms other than DC-SIGNR-mediated trans infection might operate during vertical transmission of HIV-1. For example, DC-SIGNR has also been shown to function as a HIV-1 antigen-capturing receptor . Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response .
| 630
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How does Mannanose Binding Lectin (MBL) affect elimination of HIV-1 pathogen?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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BACKGROUND: Mother-to-child transmission MTCT is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin L-SIGN , can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1. METHODS AND FINDINGS: To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes H1-H1, H1-H3, H3-H3 had a 3.6-fold increased risk of in utero IU P = 0.013 HIV-1 infection and a 5.7-fold increased risk of intrapartum IP P = 0.025 HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms SNPs in promoter region p-198A and intron 2 int2-180A that were associated with increased risk of both IU P = 0.045 and P = 0.003, respectively and IP P = 0.025, for int2-180A HIV-1 infection. The promoter variant reduced transcriptional activity in vitro.
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How does Mannanose Binding Lectin (MBL) affect elimination of HIV-1 pathogen?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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How does Mannanose Binding Lectin (MBL) affect elimination of HIV-1 pathogen?
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Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 . In this study, we demonstrate for the first time, the potential functional impact of DC-SIGNR mutations on its expression in the placenta and in vertical transmission of HIV-1. We believe that the presence of DC-SIGNR at the placental endothelial cell surface may protect infants from HIV-1 infection by capturing virus and promoting its degradation/presentation. However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation.
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Such process called microtransfusion has been proposed in regards to the results obtain in a Malawian cohort. Kweik and colleagues found a significant association between levels of maternal DNA in umbilical cord blood and IP transmission of HIV-1 suggesting that passage of maternal infected cells through the placenta is likely to occur during delivery . Thus, in a similar fashion as suggested earlier for IU transmission, the relatively lower level of DC-SIGNR in the placenta of homozygous infants harbouring the int2-180A variant could promote HIV-1 binding to CCR5 receptor on endothelial cells affecting the placental barrier integrity and facilitating the passage of maternal infected cells in foetal circulation during delivery. Beside DC-SIGNR, other HIV-1 receptors are known to influence MTCT of HIV-1 reviewed in . Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans .
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How can CCR5's effect in HIV-1 transmission be reduced?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response . The HIV-1 coreceptor CCR5, but not CD4, is co-expressed with DC-SIGNR on placental and blood-brain barrier BBB endothelial cells . HIV-1 gp120 binding to CCR5 receptor on endothelial cells compromises BBB integrity and enhances monocytes adhesion and transmigration across the BBB . It is thus possible that reduced expression of DC-SIGNR, particularly the membranebound isoforms, on placental capillary endothelial cells might favour HIV-1 binding to CCR5 receptor, instead of DC-SIGNR receptor, facilitating the migration of maternal HIV-1-infected cells across the placental barrier resulting in IU transmission of HIV-1. The int2-180A variant contained in the H1 and H3 haplotypes was associated with IP transmission suggesting that DC-SIGNR also affect transmission of HIV-1 during delivery.
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How can CCR5's effect in HIV-1 transmission be reduced?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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To date, most studies have focused on the potential role of DC-SIGNR in trans infection of HIV-1 in vitro . However, the multiple mechanisms involved in trans infection and redundancy among C-type lectin functions make it difficult to determine the actual participation of DC-SIGNR in this mode of infection in vivo . The strong correlation we observed between MTCT of HIV-1 and DC-SIGNR genetic variants producing low levels of DC-SIGNR in the placenta suggested that mechanisms other than DC-SIGNR-mediated trans infection might operate during vertical transmission of HIV-1. For example, DC-SIGNR has also been shown to function as a HIV-1 antigen-capturing receptor . Chan and colleagues recently demonstrated that DC-SIGNR transfected CHO cells diminish SARS-CoV titers by enhanced capture and degradation of the virus in a proteasome-dependent manner . Since endothelial cells express MHC-I and II, degraded viral antigens could then be presented to immune cells to elicit an adaptive immune response .
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How can CCR5's effect in HIV-1 transmission be reduced?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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Such process called microtransfusion has been proposed in regards to the results obtain in a Malawian cohort. Kweik and colleagues found a significant association between levels of maternal DNA in umbilical cord blood and IP transmission of HIV-1 suggesting that passage of maternal infected cells through the placenta is likely to occur during delivery . Thus, in a similar fashion as suggested earlier for IU transmission, the relatively lower level of DC-SIGNR in the placenta of homozygous infants harbouring the int2-180A variant could promote HIV-1 binding to CCR5 receptor on endothelial cells affecting the placental barrier integrity and facilitating the passage of maternal infected cells in foetal circulation during delivery. Beside DC-SIGNR, other HIV-1 receptors are known to influence MTCT of HIV-1 reviewed in . Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans .
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How can CCR5's effect in HIV-1 transmission be reduced?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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High maternal viral load, low CD4 cells count, vaginal delivery, low gestational age have all been identified as independent factors associated with MTCT of HIV-1 . Although antiretrovirals can reduce MTCT to 2%, limited access to timely diagnostics and drugs in many developing world countries limits the potential impact of this strategy. A better understanding of the mechanisms acting at the maternal-fetal interface is crucial for the design of alternative interventions to antiretroviral therapy for transmission prevention. Dendritic cell-specific ICAM-grabbing non-integrin-related DC-SIGNR, also known as CD209L or liver/lymph node-specific ICAM-grabbing non-integrin L-SIGN can interact with a plethora of pathogens including HIV-1 and is expressed in placental capillary endothelial cells . DC-SIGNR is organized in three distinct domains, an N-terminal cytoplasmic tail, a repeat region containing seven repeat of 23 amino acids and a C-terminal domain implicated in pathogen binding. Alternative splicing of DC-SIGNR gene leads to the production of a highly diversify isoforms repertoire which includes membrane-bound and soluble isoforms .
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How can CCR5's effect in HIV-1 transmission be reduced?
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Genetic variants in CCR5 have been shown to influence vertical transmission of HIV-1. CCR5 promoter variants resulting in higher expression of the receptor were associated with increased risk of MTCT of HIV-1 among sub-Saharan Africans . The 32-pb deletion polymorphism in CCR5 has be shown to protect from vertical transmission of HIV-1 , but this variant is virtually absent among African populations . High copy numbers of CCL3L1, a potent HIV-1 suppressive ligand for CCR5, are associated with higher chemokine production and lower risk of MTCT of HIV-1 among South African infants . Mannose-binding lectin MBL is an innate immune receptor synthesised in the liver and secreted in the bloodstream in response to inflammation signal. MBL promotes pathogen elimination by opsonization and phagocytosis, and reduced expression of MBL resulting from polymorphism in coding and non-coding regions has been associated with an increased risk of MTCT of HIV-1 .
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However, in placenta containing low levels of DC-SIGNR, HIV-1 would preferentially binds CCR5 on endothelial cells resulting in a loss of placental barrier integrity and enhanced passage of maternal HIV-1-infected cells in foetal circulation leading to MTCT of HIV-1. This mechanism may also apply to other vertically-transmitted pathogens known to interact with DC-SIGNR such as HIV-2, hepatitis C and dengue viruses and warrant further investigation. Associations between child DC-SIGNR exon 4 repeated region genotypes and mother-to-child HIV-1 transmission.CI, Confidence interval; N, number; NA; not applicable; OR, odds ratio a P-value as determined by the Chi-square test. b Comparison between genotype and all others. Found at: .1371/journal.pone.0007211.s003 Figure S1 DC-SIGNR transcripts repertoire in placenta. Major RT-PCR products from RNA extract from 3 homozygous H1 and 3 homozygous WT placenta samples were purified, cloned and sequenced.
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What is IFITM?
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The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation. Text: The interferon-induced transmembrane IFITM protein family also known as the Fragilis family in mice is a part of the dispanin family and is composed of double-transmembrane α-helices connected by a cytoplasmic CP loop and extracellular EC amino-and carboxyl-terminal polypeptide sequences Figure 1-A . The IFITM proteins are evolutionarily conserved in vertebrates . Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present.
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The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
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What is IFITM?
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The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation. Text: The interferon-induced transmembrane IFITM protein family also known as the Fragilis family in mice is a part of the dispanin family and is composed of double-transmembrane α-helices connected by a cytoplasmic CP loop and extracellular EC amino-and carboxyl-terminal polypeptide sequences Figure 1-A . The IFITM proteins are evolutionarily conserved in vertebrates . Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present.
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Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C . In addition, IFITM5 has an aspartate-rich domain in the C-terminal region, which could be involved in calcium binding Figure 1 -A . iii Role of IFITM5 in bone formation: The expression of IFITM5 is associated with mineralization during the bone formation process in osteoblast cells . Previous studies have confirmed the expression of IFITM5 in bone tissues in mice, rats, humans and tammar wallabies . The ifitm5-gene knockout mice have smaller bones .
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What is IFITM?
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The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation. Text: The interferon-induced transmembrane IFITM protein family also known as the Fragilis family in mice is a part of the dispanin family and is composed of double-transmembrane α-helices connected by a cytoplasmic CP loop and extracellular EC amino-and carboxyl-terminal polypeptide sequences Figure 1-A . The IFITM proteins are evolutionarily conserved in vertebrates . Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present.
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Recently, one of the interferon-induced transmembrane IFITM family proteins, IFITM3, has become an important target for the activity against influenza A H1N1 virus infection. In this protein, a post-translational modification by fatty acids covalently attached to cysteine, termed S-palmitoylation, plays a crucial role for the antiviral activity. IFITM3 possesses three cysteine residues for the S-palmitoylation in the first transmembrane TM1 domain and in the cytoplasmic CP loop. Because these cysteines are well conserved in the mammalian IFITM family proteins, the S-palmitoylation on these cysteines is significant for their functions. IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression.
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What is IFITM?
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The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation. Text: The interferon-induced transmembrane IFITM protein family also known as the Fragilis family in mice is a part of the dispanin family and is composed of double-transmembrane α-helices connected by a cytoplasmic CP loop and extracellular EC amino-and carboxyl-terminal polypeptide sequences Figure 1-A . The IFITM proteins are evolutionarily conserved in vertebrates . Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present.
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IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression. Our investigations using an established reporter, 17-octadecynoic acid 17-ODYA , and an inhibitor for the S-palmitoylation, 2-bromopalmitic acid 2BP , revealed that IFITM5 was S-palmitoylated in addition to IFITM3. Specifically, we found that cysteine residues in the TM1 domain and in the CP loop were S-palmitoylated in IFITM5. Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11.
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What is IFITM?
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The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation. Text: The interferon-induced transmembrane IFITM protein family also known as the Fragilis family in mice is a part of the dispanin family and is composed of double-transmembrane α-helices connected by a cytoplasmic CP loop and extracellular EC amino-and carboxyl-terminal polypeptide sequences Figure 1-A . The IFITM proteins are evolutionarily conserved in vertebrates . Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present.
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The authors revealed that IFITM3 is S-palmitoylated on three membrane proximal cysteines, Cys71 and Cys72 in the first transmembrane TM1 domain, and Cys105 in the CP loop Figure 1-A . In addition, IFITM3 lacking the S-palmitoylation is not clustered in the cell membrane and significantly diminishes the antiviral activity. Moreover, the cysteines in IFITM2, Cys70, Cys71, and Cys104 are also palmitoylated in the same manner, which affects the intracellular localization . A resent study has revealed that murine IFITM1 has four cysteine residues Cys49, Cys50, Cys83, and Cys103 for the S-palmitoylation, which is required for the antiviral activity and the protein stability . The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein .
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How many cysteine residues are contained in the first transmembrane domain of IFITM3?
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The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes. Finally, IFITM5 forms the IFITM5-FKBP11-CD81-FPRP complex. It is unknown at present which of the three states i ~ iii illustrated in Figure 6 -B is important for the bone mineralization of the osteoblast cells. The lack of the S-palmitoylation influences the interaction with FKBP11, which could account for the following complex formation and gene expression. In addition, the bone nodule formation is also affected.
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The authors revealed that IFITM3 is S-palmitoylated on three membrane proximal cysteines, Cys71 and Cys72 in the first transmembrane TM1 domain, and Cys105 in the CP loop Figure 1-A . In addition, IFITM3 lacking the S-palmitoylation is not clustered in the cell membrane and significantly diminishes the antiviral activity. Moreover, the cysteines in IFITM2, Cys70, Cys71, and Cys104 are also palmitoylated in the same manner, which affects the intracellular localization . A resent study has revealed that murine IFITM1 has four cysteine residues Cys49, Cys50, Cys83, and Cys103 for the S-palmitoylation, which is required for the antiviral activity and the protein stability . The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein .
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How many cysteine residues are contained in the first transmembrane domain of IFITM3?
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The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes. Finally, IFITM5 forms the IFITM5-FKBP11-CD81-FPRP complex. It is unknown at present which of the three states i ~ iii illustrated in Figure 6 -B is important for the bone mineralization of the osteoblast cells. The lack of the S-palmitoylation influences the interaction with FKBP11, which could account for the following complex formation and gene expression. In addition, the bone nodule formation is also affected.
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The residues unique in IFITM5 are highlighted in gray. The first and the second transmembrane domains, the extracellular sequences, and the cytoplasmic loop are indicated by arrows and denoted as TM1 and TM2, EC, and the CP loop, respectively. The TM domains were predicted by SOSUI. The aspartates at the C-terminal region in IFITM5 are shown in blue. B The schematic illustration of the protein S-palmitoylation. The C 16 -palmitic acid is attached to cysteine via a thioester linkage. The palmitoylation and depalmitoylation are catalyzed by protein acyltransferases and acylprotein thioesterases, respectively. In this study, hydroxylamine, NH 2 OH, was used to reduce the thioester linkage.
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How many cysteine residues are contained in the first transmembrane domain of IFITM3?
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The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes. Finally, IFITM5 forms the IFITM5-FKBP11-CD81-FPRP complex. It is unknown at present which of the three states i ~ iii illustrated in Figure 6 -B is important for the bone mineralization of the osteoblast cells. The lack of the S-palmitoylation influences the interaction with FKBP11, which could account for the following complex formation and gene expression. In addition, the bone nodule formation is also affected.
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Therefore, we concluded that the IFITM5 expressed in the native osteoblast cells is S-palmitoylated. In addition, the bands corresponding to the high and the low molecular-mass forms shown in western blot analysis were tentatively assigned to the S-palmitoylated and the depalmitoylated forms, respectively. As described above in the Introduction, cysteine residues are the substrate for S-palmitoylation. IFITM5 possesses three cysteines, Cys52 and Cys53 in the TM1 domain, and Cys86 in the CP loop Figure 1-A . All of these cysteines are highly conserved among the mammalian IFITM family proteins Figure 3-A . To identify the modification site in IFITM5, we prepared cysteine-substituted mutants, IFITM5-C52A/C53A, -C86A, and -C52A/C53A/C86A Cys-less .
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How many cysteine residues are contained in the first transmembrane domain of IFITM3?
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The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes. Finally, IFITM5 forms the IFITM5-FKBP11-CD81-FPRP complex. It is unknown at present which of the three states i ~ iii illustrated in Figure 6 -B is important for the bone mineralization of the osteoblast cells. The lack of the S-palmitoylation influences the interaction with FKBP11, which could account for the following complex formation and gene expression. In addition, the bone nodule formation is also affected.
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Therefore, we concluded that Cys86, plus one or two other cysteine residues in IFITM5, i.e., Cys52 and/or Cys53, are S-palmitoylated. In addition, it was found that the S-palmitoylation on the TM1 domain has a major effect on the mobility in the gel lower panel of Figure 2 -D and Figure 3-B . Therefore, we hereafter refer to the high and low molecular-mass forms as the TM1palmitoylated and the TM1-depalmitoylated forms, respectively. Finally, we reassigned the bands shown in the western blot analysis as follows: IFITM5-WT is fully palmitoylated, the C86A mutant is partially palmitoylated at Cys52 and/or Cys53, the C52A/C53A mutant is partially palmitoylated at Cys86, and the Cys-less mutant is completely depalmitoylated. Previous studies have revealed that IFITM5 interacts with FKBP11 . FKBP11 belongs to the FK506-binding protein family and has a transmembrane domain.
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How many cysteine residues are contained in the first transmembrane domain of IFITM3?
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The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes. Finally, IFITM5 forms the IFITM5-FKBP11-CD81-FPRP complex. It is unknown at present which of the three states i ~ iii illustrated in Figure 6 -B is important for the bone mineralization of the osteoblast cells. The lack of the S-palmitoylation influences the interaction with FKBP11, which could account for the following complex formation and gene expression. In addition, the bone nodule formation is also affected.
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Our investigation revealed that Cys86 is involved in the Spalmitoylation but does not contribute to the interaction with FKBP11. We speculate that some other residues in the CP loop located near the TM1 domain make some contribution to the interaction. Previous investigations also revealed that IFITM5 expressed in the heterologous fibroblast NIH3T3 cells exhibited direct interactions with CD81, the B cell receptor-associated protein 31 BCAP31 , and the hydroxysteroid 17-beta dehydrogenase 7 HSD17b7 . These three proteins bind to the IFITM5 without the S-palmitoylation low molecular-mass form; see Figure 3 -b in ref . and Figure 1 -B in ref . . In the fibroblast cells, the S-palmitoylation on IFITM5 is insufficient .
| 650
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How many cysteine residues are contained in the first transmembrane domain of IFITM3?
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The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes. Finally, IFITM5 forms the IFITM5-FKBP11-CD81-FPRP complex. It is unknown at present which of the three states i ~ iii illustrated in Figure 6 -B is important for the bone mineralization of the osteoblast cells. The lack of the S-palmitoylation influences the interaction with FKBP11, which could account for the following complex formation and gene expression. In addition, the bone nodule formation is also affected.
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In the case of IFITM3, as shown in Figure 6 -A, the following are observed. i The three cysteines are all S-palmitoylated ii . The S-palmitoylation leads to the clustering and the correct positioning of IFITM3 molecules in the membrane iii . The Spalmitoylation and the following clustering are crucial for the resistance to the influenza virus. When IFITM3 lacks the Spalmitoylation, the IFITM3 molecules do not cluster, which leads to the significant decrease in the antiviral activity. On the other hand, Figure 6 -B shows that the following observations are made in the case of IFITM5.
| 650
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What inhibits S-palmitoylation?
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When necessary, 2-bromopalmitic acid 2BP; Wako, Osaka, Japan and 17-octadecynoic acid 17-ODYA; Sigma-Aldrich were dissolved in 99.5% dimethyl sulfoxide DMSO; Wako and added to differentiation medium at concentrations of 100 μM and 50 μM in less than 0.1% DMSO, respectively . Wild-type and mutant IFITM5 proteins were also produced using an E. coli recombinant expression system. E. coli BL21 DE3 cells transformed by the expression plasmid were grown at 37°C in LB medium containing 50 μg/mL ampicillin. After four-hour induction by 1 mM isopropyl β-Dthiogalactopyranoside IPTG , cells were harvested by centrifugation 6,400 × g for 10 min at 4°C . The cells were suspended in 50 mM Tris-HCl buffer pH 8 and disrupted by a French press Ohtake, Tokyo, Japan 100 MPa × 4 times . The crude membrane fraction was collected by ultracentrifugation 178,000 × g for 90 min at 4°C .
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The S-palmitoylation is a post-translational modification on proteins by C 16 saturated-fatty acids palmitic acids covalently attached to certain cysteine residues via a thioester linkage Figure 1-B . The modification is reversibly catalyzed by protein acyltransferases and acylprotein thioesterases, and confers unique properties to the protein, such as membrane binding and targeting, immunoreactivity, Amino-acid sequence alignment of IFITM5, IFITM1, IFITM2, and IFITM3 derived from mice. The conserved residues are highlighted in black. The three conserved cysteines are highlighted in red and numbered based on the sequence of IFITM5 top and IFITM3 bottom . The residues unique in IFITM5 are highlighted in gray. The first and the second transmembrane domains, the extracellular sequences, and the cytoplasmic loop are indicated by arrows and denoted as TM1 and TM2, EC, and the CP loop, respectively.
| 650
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What inhibits S-palmitoylation?
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When necessary, 2-bromopalmitic acid 2BP; Wako, Osaka, Japan and 17-octadecynoic acid 17-ODYA; Sigma-Aldrich were dissolved in 99.5% dimethyl sulfoxide DMSO; Wako and added to differentiation medium at concentrations of 100 μM and 50 μM in less than 0.1% DMSO, respectively . Wild-type and mutant IFITM5 proteins were also produced using an E. coli recombinant expression system. E. coli BL21 DE3 cells transformed by the expression plasmid were grown at 37°C in LB medium containing 50 μg/mL ampicillin. After four-hour induction by 1 mM isopropyl β-Dthiogalactopyranoside IPTG , cells were harvested by centrifugation 6,400 × g for 10 min at 4°C . The cells were suspended in 50 mM Tris-HCl buffer pH 8 and disrupted by a French press Ohtake, Tokyo, Japan 100 MPa × 4 times . The crude membrane fraction was collected by ultracentrifugation 178,000 × g for 90 min at 4°C .
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The palmitoylation and depalmitoylation are catalyzed by protein acyltransferases and acylprotein thioesterases, respectively. In this study, hydroxylamine, NH 2 OH, was used to reduce the thioester linkage. C The amino acid sequence identity similarity among IFITM5, IFITM1, IFITM2, and IFITM3 is summarized. .1371/journal.pone.0075831.g001 and protein-protein interaction. The authors revealed that IFITM3 is S-palmitoylated on three membrane proximal cysteines, Cys71 and Cys72 in the first transmembrane TM1 domain, and Cys105 in the CP loop Figure 1-A . In addition, IFITM3 lacking the S-palmitoylation is not clustered in the cell membrane and significantly diminishes the antiviral activity.
| 650
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What inhibits S-palmitoylation?
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When necessary, 2-bromopalmitic acid 2BP; Wako, Osaka, Japan and 17-octadecynoic acid 17-ODYA; Sigma-Aldrich were dissolved in 99.5% dimethyl sulfoxide DMSO; Wako and added to differentiation medium at concentrations of 100 μM and 50 μM in less than 0.1% DMSO, respectively . Wild-type and mutant IFITM5 proteins were also produced using an E. coli recombinant expression system. E. coli BL21 DE3 cells transformed by the expression plasmid were grown at 37°C in LB medium containing 50 μg/mL ampicillin. After four-hour induction by 1 mM isopropyl β-Dthiogalactopyranoside IPTG , cells were harvested by centrifugation 6,400 × g for 10 min at 4°C . The cells were suspended in 50 mM Tris-HCl buffer pH 8 and disrupted by a French press Ohtake, Tokyo, Japan 100 MPa × 4 times . The crude membrane fraction was collected by ultracentrifugation 178,000 × g for 90 min at 4°C .
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In the C52A/C53A and Cys-less mutants see lanes 2 and 4 , the low molecular-mass form was detected. This result indicates that either Cys52 or Cys53 is involved in the S-palmitoylation. In addition, as shown in Figure 2 -D, strong and weak fluorescence were detected in the C52A/ C53A mutant in the absence and presence of hydroxylamine lanes 3 and 7 , respectively, but not in the Cys-less mutant lanes 4 and 8 . These results suggested that the rest of the cysteine in the C52A/C53A mutant, Cys86, is S-palmitoylated and the Cys-less mutant completely lost the S-palmitoylation because all the cysteines were substituted. Therefore, we concluded that Cys86, plus one or two other cysteine residues in IFITM5, i.e., Cys52 and/or Cys53, are S-palmitoylated. In addition, it was found that the S-palmitoylation on the TM1 domain has a major effect on the mobility in the gel lower panel of Figure 2 -D and Figure 3-B .
| 650
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What inhibits S-palmitoylation?
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When necessary, 2-bromopalmitic acid 2BP; Wako, Osaka, Japan and 17-octadecynoic acid 17-ODYA; Sigma-Aldrich were dissolved in 99.5% dimethyl sulfoxide DMSO; Wako and added to differentiation medium at concentrations of 100 μM and 50 μM in less than 0.1% DMSO, respectively . Wild-type and mutant IFITM5 proteins were also produced using an E. coli recombinant expression system. E. coli BL21 DE3 cells transformed by the expression plasmid were grown at 37°C in LB medium containing 50 μg/mL ampicillin. After four-hour induction by 1 mM isopropyl β-Dthiogalactopyranoside IPTG , cells were harvested by centrifugation 6,400 × g for 10 min at 4°C . The cells were suspended in 50 mM Tris-HCl buffer pH 8 and disrupted by a French press Ohtake, Tokyo, Japan 100 MPa × 4 times . The crude membrane fraction was collected by ultracentrifugation 178,000 × g for 90 min at 4°C .
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In this study, we confirmed the S-palmitoylation on IFITM5 in the osteoblast cells, which was the same as that previously reported for IFITM3 and IFITM2. As reported previously, in IFITM3 and IFITM2, which share 85% sequence similarity Figure 1-C , two cysteines in the TM1 domain Cys71 and Cys72 for IFITM3, Cys70 and Cys71 for IFITM2 and one cysteine in the CP loop Cys105 for IFITM3, Cys104 for IFITM2 are all S-palmitoylated in cells . On the other hand, although IFITM5 shares 68% and 66% sequence similarity to IFITM3 and IFITM2, respectively, more than one cysteine in the TM1 domain Cys52 or Cys53 and one cysteine in the CP loop Cys86 are S-palmitoylated. Taking into account the high conservation of three cysteines in the IFITM proteins Figures 1-A and 3-A , all the cysteines in IFITM5 may be involved in the S-palmitoylation just as in the case of IFITM3 and IFITM2 . The roles of the S-palmitoylation on IFITM3 have been studied intensively, and the S-palmitoylation has been shown to be crucial for the correct positioning in the membrane and the resistance to viral infection and internalization the roles are summarized in Figure 6 -A and discussed in detail below . A recent study has revealed that the S-palmitoylation on IFITM2 is also important for the protein clustering in the membrane .
| 650
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What inhibits S-palmitoylation?
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When necessary, 2-bromopalmitic acid 2BP; Wako, Osaka, Japan and 17-octadecynoic acid 17-ODYA; Sigma-Aldrich were dissolved in 99.5% dimethyl sulfoxide DMSO; Wako and added to differentiation medium at concentrations of 100 μM and 50 μM in less than 0.1% DMSO, respectively . Wild-type and mutant IFITM5 proteins were also produced using an E. coli recombinant expression system. E. coli BL21 DE3 cells transformed by the expression plasmid were grown at 37°C in LB medium containing 50 μg/mL ampicillin. After four-hour induction by 1 mM isopropyl β-Dthiogalactopyranoside IPTG , cells were harvested by centrifugation 6,400 × g for 10 min at 4°C . The cells were suspended in 50 mM Tris-HCl buffer pH 8 and disrupted by a French press Ohtake, Tokyo, Japan 100 MPa × 4 times . The crude membrane fraction was collected by ultracentrifugation 178,000 × g for 90 min at 4°C .
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These results suggested that IFITM5-WT has high and low molecular-mass forms in the absence and presence of 2BP, respectively. The S-palmitoylation is a reversible reaction, and therefore is depalmitoylated by a strong reductant such as hydroxylamine . Following hydroxylamine treatment see lane 2 , the band appeared at the same position as in the presence of 2BP lane 4 . In prokaryote E. coli cells, the post-translational modification S-Palmitoylation on IFITM5 PLOS ONE | does not occur. Hence, the band was also observed at the same lower position see lane 3 . In the case of IFITM3, the palmitoylation was also reported to induce a change in mobility on electrophoresis, just as in our present results .
| 650
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What inhibits S-palmitoylation?
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When necessary, 2-bromopalmitic acid 2BP; Wako, Osaka, Japan and 17-octadecynoic acid 17-ODYA; Sigma-Aldrich were dissolved in 99.5% dimethyl sulfoxide DMSO; Wako and added to differentiation medium at concentrations of 100 μM and 50 μM in less than 0.1% DMSO, respectively . Wild-type and mutant IFITM5 proteins were also produced using an E. coli recombinant expression system. E. coli BL21 DE3 cells transformed by the expression plasmid were grown at 37°C in LB medium containing 50 μg/mL ampicillin. After four-hour induction by 1 mM isopropyl β-Dthiogalactopyranoside IPTG , cells were harvested by centrifugation 6,400 × g for 10 min at 4°C . The cells were suspended in 50 mM Tris-HCl buffer pH 8 and disrupted by a French press Ohtake, Tokyo, Japan 100 MPa × 4 times . The crude membrane fraction was collected by ultracentrifugation 178,000 × g for 90 min at 4°C .
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and Figure 1 -B in ref . . In the fibroblast cells, the S-palmitoylation on IFITM5 is insufficient . These interactions are not observed in the native osteoblast cells, and therefore are nonspecific. Taking these facts into consideration, we speculate that the S-palmitoylation on IFITM5 promotes the specific interaction with FKBP11 in the osteoblast cells. The role played by the S-palmitoylation of IFITM5 in immune activity of the osteoblast cells will be discussed by combining the results from the present and the previous studies. A specific interaction between IFITM5 and FKBP11 should be necessary to form the IFITM5-FKBP11-CD81-FPRP complex.
| 650
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What interaction is inhibited by the presence of 2-bromopalmitic acid (2BP)?
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The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11. At present, however, little is known about the role of the S-palmitoylation of IFITM5 for the localization in the membrane. When the S-palmitoylation affects the localization of IFITM5 as in the case of IFITM3 , the S-palmitoylated IFITM5 molecules should be localized in the membrane or the depalmitoylated molecules should be delocalized. The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes.
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While 2BP is commonly used as an inhibitor of palmitoylation, it also targets many metabolic enzymes . Thus, it is also difficult to interpret the results of the long-term incubation of the osteoblast cells in the presence of 2BP. In any case, these are interesting and key observations in terms of clarifying the role played by the S-palmitoylation of IFITM5 in bone formation, and further studies are required. Figure 6 describes a possible mechanism of the interaction of IFITM5 with FKBP11 and the role of IFITM5 in the osteoblast cell function by means of a comparison with IFITM3. In the case of IFITM3, as shown in Figure 6 -A, the following are observed. i The three cysteines are all S-palmitoylated ii .
| 650
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What interaction is inhibited by the presence of 2-bromopalmitic acid (2BP)?
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The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11. At present, however, little is known about the role of the S-palmitoylation of IFITM5 for the localization in the membrane. When the S-palmitoylation affects the localization of IFITM5 as in the case of IFITM3 , the S-palmitoylated IFITM5 molecules should be localized in the membrane or the depalmitoylated molecules should be delocalized. The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes.
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Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
| 650
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What interaction is inhibited by the presence of 2-bromopalmitic acid (2BP)?
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The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11. At present, however, little is known about the role of the S-palmitoylation of IFITM5 for the localization in the membrane. When the S-palmitoylation affects the localization of IFITM5 as in the case of IFITM3 , the S-palmitoylated IFITM5 molecules should be localized in the membrane or the depalmitoylated molecules should be delocalized. The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes.
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If the Spalmitoylation-mediated specific interaction of IFITM5 with FKBP11 were lost, the IFITM5-FKBP11-CD81-FPRP complex would not be formed, and consequently the interferon-induced gene expression would be inhibited because CD9 would remain associated with the FKBP11-CD81-FPRP/CD9 complex. In this respect, we speculate that IFITM5 is involved in the immune system activity in the osteoblast cells and the interaction of the S-palmitoylated IFITM5 with FKBP11 regulates the immune activity. In addition, it was suggested that the S-palmitoylation on IFITM5 contributes to the bone nodule formation, including morphology and time for mineralization, in the osteoblast cells Figure 5 . It is difficult to conclude at present that the lack of the S-palmitoylation on IFITM5 causes the diffusion of the bone nodules panel b of Figure 5 -E ; we can say, however, that IFITM5 will probably not be S-palmitoylated in the cells in the presence of 2BP. While 2BP is commonly used as an inhibitor of palmitoylation, it also targets many metabolic enzymes . Thus, it is also difficult to interpret the results of the long-term incubation of the osteoblast cells in the presence of 2BP.
| 650
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What interaction is inhibited by the presence of 2-bromopalmitic acid (2BP)?
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The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11. At present, however, little is known about the role of the S-palmitoylation of IFITM5 for the localization in the membrane. When the S-palmitoylation affects the localization of IFITM5 as in the case of IFITM3 , the S-palmitoylated IFITM5 molecules should be localized in the membrane or the depalmitoylated molecules should be delocalized. The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes.
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IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression. Our investigations using an established reporter, 17-octadecynoic acid 17-ODYA , and an inhibitor for the S-palmitoylation, 2-bromopalmitic acid 2BP , revealed that IFITM5 was S-palmitoylated in addition to IFITM3. Specifically, we found that cysteine residues in the TM1 domain and in the CP loop were S-palmitoylated in IFITM5. Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11.
| 650
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What interaction is inhibited by the presence of 2-bromopalmitic acid (2BP)?
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The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11. At present, however, little is known about the role of the S-palmitoylation of IFITM5 for the localization in the membrane. When the S-palmitoylation affects the localization of IFITM5 as in the case of IFITM3 , the S-palmitoylated IFITM5 molecules should be localized in the membrane or the depalmitoylated molecules should be delocalized. The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes.
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and Figure 1 -B in ref . . In the fibroblast cells, the S-palmitoylation on IFITM5 is insufficient . These interactions are not observed in the native osteoblast cells, and therefore are nonspecific. Taking these facts into consideration, we speculate that the S-palmitoylation on IFITM5 promotes the specific interaction with FKBP11 in the osteoblast cells. The role played by the S-palmitoylation of IFITM5 in immune activity of the osteoblast cells will be discussed by combining the results from the present and the previous studies. A specific interaction between IFITM5 and FKBP11 should be necessary to form the IFITM5-FKBP11-CD81-FPRP complex.
| 650
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What interaction is inhibited by the presence of 2-bromopalmitic acid (2BP)?
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The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11. At present, however, little is known about the role of the S-palmitoylation of IFITM5 for the localization in the membrane. When the S-palmitoylation affects the localization of IFITM5 as in the case of IFITM3 , the S-palmitoylated IFITM5 molecules should be localized in the membrane or the depalmitoylated molecules should be delocalized. The loss of the interaction between IFITM5 and FKBP11 could be due to a relocalization of the depalmitoylated IFITM5 that prevents its association with FKBP11 iii . The Spalmitoylated IFITM5 interacts with the FKBP11-CD81-FPRP/CD9 complex through FKBP11, which induces the dissociation of CD9 from the complex and the expression of 5 immunologically relevant genes.
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The controls also ensured that IFITM5 was S-palmitoylated in the absence of 2BP see lane 1 , whereas IFITM5 was not S-palmitoylated in the presence of 2BP see lane 2 . After the immunoprecipitation, a single band corresponding to the S-palmitoylated IFITM5 appeared in the absence of 2BP see lane 3 , indicating the interaction of the Spalmitoylated IFITM5 with FKBP11. However, in the presence of 2BP, no band corresponding to IFITM5 appeared see lane 4 , indicating that the two molecules do not interact with each other. These results suggest that the S-palmitoylation on IFITM5 contributes to the interaction with FKBP11. Next, we further investigated the relationship between the Spalmitoylation and the interaction with FKBP11 by using the IFITM5 mutants described above. The osteoblast cells cotransfected by the plasmids encoding IFITM5 mutants C52A/ C53A, C86A, and Cys-less and FKBP11-FLAG were cultured.
| 650
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What is a function associated with IFITM5?
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Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
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Previous studies have confirmed the expression of IFITM5 in bone tissues in mice, rats, humans and tammar wallabies . The ifitm5-gene knockout mice have smaller bones . Moreover, the knockdown of the ifitm5 gene by small hairpin RNA induces a decrease in bone nodule formation, whereas overexpression of the gene in UMR106 cells has been shown to increase calcium uptake and bone nodule formation . iv Role of IFITM5 for immune activity: Recent studies have revealed that IFITM5 interacts with the FK506-binding protein 11 FKBP11 to form IFITM5-FKBP11-CD81-the prostaglandin F2 receptor negative regulator FPRP complex . When the complex is formed, the expressions of 5 interferon-induced genes are induced, including bone marrow stromal cell antigen 2 Bst2 , interferon inducible protein 1 Irgm , interferoninduced protein with tetratricopeptide repeats 3 Ifit3 , b.microglobulin B2m , and MHC class I antigen gene. Consequently, these results indicate that IFITM5 is involved not only in the bone formation but also in the immune system activity.
| 650
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What is a function associated with IFITM5?
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Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
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IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression. Our investigations using an established reporter, 17-octadecynoic acid 17-ODYA , and an inhibitor for the S-palmitoylation, 2-bromopalmitic acid 2BP , revealed that IFITM5 was S-palmitoylated in addition to IFITM3. Specifically, we found that cysteine residues in the TM1 domain and in the CP loop were S-palmitoylated in IFITM5. Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11.
| 650
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What is a function associated with IFITM5?
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Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
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Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C . In addition, IFITM5 has an aspartate-rich domain in the C-terminal region, which could be involved in calcium binding Figure 1 -A . iii Role of IFITM5 in bone formation: The expression of IFITM5 is associated with mineralization during the bone formation process in osteoblast cells . Previous studies have confirmed the expression of IFITM5 in bone tissues in mice, rats, humans and tammar wallabies . The ifitm5-gene knockout mice have smaller bones .
| 650
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What is a function associated with IFITM5?
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Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
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Recently, one of the interferon-induced transmembrane IFITM family proteins, IFITM3, has become an important target for the activity against influenza A H1N1 virus infection. In this protein, a post-translational modification by fatty acids covalently attached to cysteine, termed S-palmitoylation, plays a crucial role for the antiviral activity. IFITM3 possesses three cysteine residues for the S-palmitoylation in the first transmembrane TM1 domain and in the cytoplasmic CP loop. Because these cysteines are well conserved in the mammalian IFITM family proteins, the S-palmitoylation on these cysteines is significant for their functions. IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression.
| 650
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What is a function associated with IFITM5?
|
Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
| 650
|
What is a function associated with IFITM5?
|
Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11. These results indicate that the S-palmitoylation on IFITM5 promotes the interaction with FKBP11. Finally, we investigated bone nodule formation in osteoblast cells in the presence of 2BP, because IFITM5 was originally identified as a bone formation factor. The experiment resulted in a morphological aberration of the bone nodule. This also indicated that the S-palmitoylation contributes to bone formation.
|
A The functional mechanism of IFITM3 is summarized from previous studies. i IFITM3 is S-palmitoylated at Cys71, Cys72, and Cys105, ii which induces clustering and correct positioning in the membrane, iii resulting in the antiviral activity against influenza virus. B The functional mechanism of IFITM5 is summarized by combining the results from the present and the previous studies. i Cys86, plus one or two other cysteine residues in IFITM5, i.e., Cys52 and/or Cys53, are S-palmitoylated ii . The S-palmitoylation allows IFITM5 to interact with FKBP11 in the osteoblast cells iii . The dissociation of CD9 from the FKBP11-CD81-FPRP/CD9 complex is induced by formation of the IFITM5-FKBP11-CD81-FPRP complex and leads to the immunologically relevant gene expression.
| 650
|
What regulates the antiviral activity of IFITM3?
|
Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present. In particular, IFITM3 has been a target of intensive studies on its activity against influenza A H1N1 virus infection and internalization . In 2010, Dr. Yount and co-workers reported that the antiviral activity of IFITM3 is dependent on S-palmitoylation on the protein . The S-palmitoylation is a post-translational modification on proteins by C 16 saturated-fatty acids palmitic acids covalently attached to certain cysteine residues via a thioester linkage Figure 1-B . The modification is reversibly catalyzed by protein acyltransferases and acylprotein thioesterases, and confers unique properties to the protein, such as membrane binding and targeting, immunoreactivity, Amino-acid sequence alignment of IFITM5, IFITM1, IFITM2, and IFITM3 derived from mice.
|
A The functional mechanism of IFITM3 is summarized from previous studies. i IFITM3 is S-palmitoylated at Cys71, Cys72, and Cys105, ii which induces clustering and correct positioning in the membrane, iii resulting in the antiviral activity against influenza virus. B The functional mechanism of IFITM5 is summarized by combining the results from the present and the previous studies. i Cys86, plus one or two other cysteine residues in IFITM5, i.e., Cys52 and/or Cys53, are S-palmitoylated ii . The S-palmitoylation allows IFITM5 to interact with FKBP11 in the osteoblast cells iii . The dissociation of CD9 from the FKBP11-CD81-FPRP/CD9 complex is induced by formation of the IFITM5-FKBP11-CD81-FPRP complex and leads to the immunologically relevant gene expression.
| 650
|
What regulates the antiviral activity of IFITM3?
|
Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present. In particular, IFITM3 has been a target of intensive studies on its activity against influenza A H1N1 virus infection and internalization . In 2010, Dr. Yount and co-workers reported that the antiviral activity of IFITM3 is dependent on S-palmitoylation on the protein . The S-palmitoylation is a post-translational modification on proteins by C 16 saturated-fatty acids palmitic acids covalently attached to certain cysteine residues via a thioester linkage Figure 1-B . The modification is reversibly catalyzed by protein acyltransferases and acylprotein thioesterases, and confers unique properties to the protein, such as membrane binding and targeting, immunoreactivity, Amino-acid sequence alignment of IFITM5, IFITM1, IFITM2, and IFITM3 derived from mice.
|
When IFITM3 lacks the Spalmitoylation, the IFITM3 molecules do not cluster, which leads to the significant decrease in the antiviral activity. On the other hand, Figure 6 -B shows that the following observations are made in the case of IFITM5. i Cys86, plus one or two other cysteine residues in IFITM5, i.e., Cys52 and/or Cys53, are S-palmitoylated ii . The S-palmitoylated IFITM5 is able to interact specifically with FKBP11. The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11.
| 650
|
What regulates the antiviral activity of IFITM3?
|
Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present. In particular, IFITM3 has been a target of intensive studies on its activity against influenza A H1N1 virus infection and internalization . In 2010, Dr. Yount and co-workers reported that the antiviral activity of IFITM3 is dependent on S-palmitoylation on the protein . The S-palmitoylation is a post-translational modification on proteins by C 16 saturated-fatty acids palmitic acids covalently attached to certain cysteine residues via a thioester linkage Figure 1-B . The modification is reversibly catalyzed by protein acyltransferases and acylprotein thioesterases, and confers unique properties to the protein, such as membrane binding and targeting, immunoreactivity, Amino-acid sequence alignment of IFITM5, IFITM1, IFITM2, and IFITM3 derived from mice.
|
Recently, one of the interferon-induced transmembrane IFITM family proteins, IFITM3, has become an important target for the activity against influenza A H1N1 virus infection. In this protein, a post-translational modification by fatty acids covalently attached to cysteine, termed S-palmitoylation, plays a crucial role for the antiviral activity. IFITM3 possesses three cysteine residues for the S-palmitoylation in the first transmembrane TM1 domain and in the cytoplasmic CP loop. Because these cysteines are well conserved in the mammalian IFITM family proteins, the S-palmitoylation on these cysteines is significant for their functions. IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression.
| 650
|
What regulates the antiviral activity of IFITM3?
|
Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present. In particular, IFITM3 has been a target of intensive studies on its activity against influenza A H1N1 virus infection and internalization . In 2010, Dr. Yount and co-workers reported that the antiviral activity of IFITM3 is dependent on S-palmitoylation on the protein . The S-palmitoylation is a post-translational modification on proteins by C 16 saturated-fatty acids palmitic acids covalently attached to certain cysteine residues via a thioester linkage Figure 1-B . The modification is reversibly catalyzed by protein acyltransferases and acylprotein thioesterases, and confers unique properties to the protein, such as membrane binding and targeting, immunoreactivity, Amino-acid sequence alignment of IFITM5, IFITM1, IFITM2, and IFITM3 derived from mice.
|
In the case of IFITM3, as shown in Figure 6 -A, the following are observed. i The three cysteines are all S-palmitoylated ii . The S-palmitoylation leads to the clustering and the correct positioning of IFITM3 molecules in the membrane iii . The Spalmitoylation and the following clustering are crucial for the resistance to the influenza virus. When IFITM3 lacks the Spalmitoylation, the IFITM3 molecules do not cluster, which leads to the significant decrease in the antiviral activity. On the other hand, Figure 6 -B shows that the following observations are made in the case of IFITM5.
| 650
|
What regulates the antiviral activity of IFITM3?
|
Recent genomic research has revealed that there are 5 IFITM members in humans IFITM1, 2, 3, 5 and 10 and 7 members in mice IFITM1, 2, 3, 5, 6, 7, and 10 . These proteins play roles in diverse biological processes, such as germ cell maturation during gastrulation IFITM1-3 , cell-to-cell adhesion IFITM1 , antiviral activity IFITM1-3 , and bone formation IFITM5 , although the detailed functions of IFITM6, 7, and 10 are unknown at present. In particular, IFITM3 has been a target of intensive studies on its activity against influenza A H1N1 virus infection and internalization . In 2010, Dr. Yount and co-workers reported that the antiviral activity of IFITM3 is dependent on S-palmitoylation on the protein . The S-palmitoylation is a post-translational modification on proteins by C 16 saturated-fatty acids palmitic acids covalently attached to certain cysteine residues via a thioester linkage Figure 1-B . The modification is reversibly catalyzed by protein acyltransferases and acylprotein thioesterases, and confers unique properties to the protein, such as membrane binding and targeting, immunoreactivity, Amino-acid sequence alignment of IFITM5, IFITM1, IFITM2, and IFITM3 derived from mice.
|
B Western blot for the co-immunoprecipitation of the wild-type and the cysteine-substituted mutants of IFITM5 with FKBP11-FLAG in the osteoblast cells. The band corresponding to FLAG peptide is not shown because of the smaller molecular-mass of FLAG peptide relative to FKBP11-FLAG. C The control experiment of Figure 4 -B used to verify that IFITM5 and FKBP11 were both present in the cell lysate before the immunoprecipitation. The experiment was repeated 2 times. A The functional mechanism of IFITM3 is summarized from previous studies. i IFITM3 is S-palmitoylated at Cys71, Cys72, and Cys105, ii which induces clustering and correct positioning in the membrane, iii resulting in the antiviral activity against influenza virus.
| 650
|
What is another name for IFITM5?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression. Our investigations using an established reporter, 17-octadecynoic acid 17-ODYA , and an inhibitor for the S-palmitoylation, 2-bromopalmitic acid 2BP , revealed that IFITM5 was S-palmitoylated in addition to IFITM3. Specifically, we found that cysteine residues in the TM1 domain and in the CP loop were S-palmitoylated in IFITM5. Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11.
| 650
|
What is another name for IFITM5?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C . In addition, IFITM5 has an aspartate-rich domain in the C-terminal region, which could be involved in calcium binding Figure 1 -A . iii Role of IFITM5 in bone formation: The expression of IFITM5 is associated with mineralization during the bone formation process in osteoblast cells . Previous studies have confirmed the expression of IFITM5 in bone tissues in mice, rats, humans and tammar wallabies . The ifitm5-gene knockout mice have smaller bones .
| 650
|
What is another name for IFITM5?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
Therefore, we concluded that the IFITM5 expressed in the native osteoblast cells is S-palmitoylated. In addition, the bands corresponding to the high and the low molecular-mass forms shown in western blot analysis were tentatively assigned to the S-palmitoylated and the depalmitoylated forms, respectively. As described above in the Introduction, cysteine residues are the substrate for S-palmitoylation. IFITM5 possesses three cysteines, Cys52 and Cys53 in the TM1 domain, and Cys86 in the CP loop Figure 1-A . All of these cysteines are highly conserved among the mammalian IFITM family proteins Figure 3-A . To identify the modification site in IFITM5, we prepared cysteine-substituted mutants, IFITM5-C52A/C53A, -C86A, and -C52A/C53A/C86A Cys-less .
| 650
|
What is another name for IFITM5?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
Recently, one of the interferon-induced transmembrane IFITM family proteins, IFITM3, has become an important target for the activity against influenza A H1N1 virus infection. In this protein, a post-translational modification by fatty acids covalently attached to cysteine, termed S-palmitoylation, plays a crucial role for the antiviral activity. IFITM3 possesses three cysteine residues for the S-palmitoylation in the first transmembrane TM1 domain and in the cytoplasmic CP loop. Because these cysteines are well conserved in the mammalian IFITM family proteins, the S-palmitoylation on these cysteines is significant for their functions. IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression.
| 650
|
What is another name for IFITM5?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
When the complex is formed, the expressions of 5 interferon-induced genes are induced, including bone marrow stromal cell antigen 2 Bst2 , interferon inducible protein 1 Irgm , interferoninduced protein with tetratricopeptide repeats 3 Ifit3 , b.microglobulin B2m , and MHC class I antigen gene. Consequently, these results indicate that IFITM5 is involved not only in the bone formation but also in the immune system activity. In this study, we investigated the S-palmitoylation of IFITM5 and its role in the interaction with FKBP11 in mouse osteoblast cells. Cells transfected by a plasmid DNA encoding mouse IFITM5 were grown in the presence of an established chemical reporter, 17-octadecynoic acid 17-ODYA , or an inhibitor for the S-palmitoylation, 2-bromopalmitic acid 2BP . The biochemical assays using these compounds revealed that the wild-type IFITM5 is S-palmitoylated. To identify the Spalmitoylation site in IFITM5, we prepared cysteine-substituted mutants, IFITM5-C86A, -C52A/C53A, and -C52A/53A/86A Cys-less .
| 650
|
Why is the expression of IFITM5 not promoted by interferons?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C . In addition, IFITM5 has an aspartate-rich domain in the C-terminal region, which could be involved in calcium binding Figure 1 -A . iii Role of IFITM5 in bone formation: The expression of IFITM5 is associated with mineralization during the bone formation process in osteoblast cells . Previous studies have confirmed the expression of IFITM5 in bone tissues in mice, rats, humans and tammar wallabies . The ifitm5-gene knockout mice have smaller bones .
| 650
|
Why is the expression of IFITM5 not promoted by interferons?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
Previous studies have confirmed the expression of IFITM5 in bone tissues in mice, rats, humans and tammar wallabies . The ifitm5-gene knockout mice have smaller bones . Moreover, the knockdown of the ifitm5 gene by small hairpin RNA induces a decrease in bone nodule formation, whereas overexpression of the gene in UMR106 cells has been shown to increase calcium uptake and bone nodule formation . iv Role of IFITM5 for immune activity: Recent studies have revealed that IFITM5 interacts with the FK506-binding protein 11 FKBP11 to form IFITM5-FKBP11-CD81-the prostaglandin F2 receptor negative regulator FPRP complex . When the complex is formed, the expressions of 5 interferon-induced genes are induced, including bone marrow stromal cell antigen 2 Bst2 , interferon inducible protein 1 Irgm , interferoninduced protein with tetratricopeptide repeats 3 Ifit3 , b.microglobulin B2m , and MHC class I antigen gene. Consequently, these results indicate that IFITM5 is involved not only in the bone formation but also in the immune system activity.
| 650
|
Why is the expression of IFITM5 not promoted by interferons?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression. Our investigations using an established reporter, 17-octadecynoic acid 17-ODYA , and an inhibitor for the S-palmitoylation, 2-bromopalmitic acid 2BP , revealed that IFITM5 was S-palmitoylated in addition to IFITM3. Specifically, we found that cysteine residues in the TM1 domain and in the CP loop were S-palmitoylated in IFITM5. Then, we revealed by immunoprecipitation and western blot analyses that the interaction of IFITM5 with FKBP11 was inhibited in the presence of 2BP. The mutant lacking the S-palmitoylation site in the TM1 domain lost the interaction with FKBP11.
| 650
|
Why is the expression of IFITM5 not promoted by interferons?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
Recently, one of the interferon-induced transmembrane IFITM family proteins, IFITM3, has become an important target for the activity against influenza A H1N1 virus infection. In this protein, a post-translational modification by fatty acids covalently attached to cysteine, termed S-palmitoylation, plays a crucial role for the antiviral activity. IFITM3 possesses three cysteine residues for the S-palmitoylation in the first transmembrane TM1 domain and in the cytoplasmic CP loop. Because these cysteines are well conserved in the mammalian IFITM family proteins, the S-palmitoylation on these cysteines is significant for their functions. IFITM5 is another IFITM family protein and interacts with the FK506-binding protein 11 FKBP11 to form a higher-order complex in osteoblast cells, which induces the expression of immunologically relevant genes. In this study, we investigated the role played by S-palmitoylation of IFITM5 in its interaction with FKBP11 in the cells, because this interaction is a key process for the gene expression.
| 650
|
Why is the expression of IFITM5 not promoted by interferons?
|
The other IFITM family members also possess these cysteines Figure 1-A , and thus the role of the Spalmitoylation on the cysteines should be significant for the functions of IFITM proteins. Here, we focused on IFITM5, which is also known as bonerestricted IFITM-like BRIL protein . Among the IFITM family proteins, IFITM5 is unique. i Expression of IFITM5: Unlike the other IFITM family proteins, the expression of IFITM5 is not induced by interferons because the region upstream of the ifitm5 gene lacks the interferon regulatory elements . Furthermore, the expression of IFITM5 is mostly restricted to osteoblast cells , while the other IFITM proteins are expressed ubiquitously ii . Amino-acid sequence similarity: The amino acid sequence of IFITM5 is relatively dissimilar to IFITM1-3 proteins ~ 65% similarity , while IFITM1-3 proteins share ~ 85% similarity with each other Figure 1 -C .
|
When IFITM3 lacks the Spalmitoylation, the IFITM3 molecules do not cluster, which leads to the significant decrease in the antiviral activity. On the other hand, Figure 6 -B shows that the following observations are made in the case of IFITM5. i Cys86, plus one or two other cysteine residues in IFITM5, i.e., Cys52 and/or Cys53, are S-palmitoylated ii . The S-palmitoylated IFITM5 is able to interact specifically with FKBP11. The interaction is presumed to be mediated by the palmitic acid s attached to the cysteine s facing toward the interaction surface on FKBP11. Cys86 is involved in the S-palmitoylation but not in the interaction of IFITM5 with FKBP11.
| 650
|
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