To clarify the role of APOBEC3G （A3G） in cellular defense against hepatitis B virus （HBV）, the expression of A3G in normal human liver and the regulation of the A3G expression in hepatoma cell line （HuH-7） were ...To clarify the role of APOBEC3G （A3G） in cellular defense against hepatitis B virus （HBV）, the expression of A3G in normal human liver and the regulation of the A3G expression in hepatoma cell line （HuH-7） were investigated. Expression level of APOBEC3s mRNA in human liver was determined by RT-PCR. HuH-7 and HepG2 cells were treated with various concentrations of IFN-α（0 U/ml, 100 U/ml, 500 U/ml, 1000 U/ml）for 12 h. The mRNA levels were measured by a quantitative RT-PCR, the results were normalized relative to the specimens without IFN-α stimulation. Total protein of HuH-7 cells treated with various concentrations of IFN-α for 48 h was subjected to Western blot analysis. For reporter gene assay, HuH-7 cells were transfected with the reporter plasmids containing IRF- E sites and its mutants with different lengths. Then the cells were treated with or without 1200 U/ml IFN-α for additional 12 h （ 1000 U/ml） after 24 h of transfection, and the cell lysate was prepared and assayed for lueiferase activity. It was found that normal human liver expressed the rnR_NA of A3G. A3G mRNA expression in HuH-7 and HepG2 cells were up-regulated by IFN-α stimulation in a dose-depen- dent manner. Western blot analysis indicated that A3G protein expression was also enhanced by IFN-α stimulation. Sequence analysis showed the existence of putative sites of IFN regulatory factor element （IRF-E） in 5＇ region of A3G gene upstream the initiation eodon. IFN-α stimulation results in 6- to 8- fold increase in lueiferase activity in cells transfeeted with the plasmid containing IRF-E sites of the 5＇ upstream sequences, whereas luciferase activity did not change in cells transfected with the plasmid containing mutant IRF-E sites or without IRF-E sites. As a conclusion, A3G are expressed in normal human liver. A3G expression was up-regulated by IFN-α stimulation in hepatoma cells and could be involved in host defense mechanisms against HBV. IRF-E site in 5＇ region of APOBEC3G gene upstream the initiation codon plays an important role in this process.展开更多
Dendritic cells （DC）, although a minor population in hematopoietic cells, produce type I interferons （IFN） and other cytokines and are essential for innate immunity. They are also potent antigen presenters and reg...Dendritic cells （DC）, although a minor population in hematopoietic cells, produce type I interferons （IFN） and other cytokines and are essential for innate immunity. They are also potent antigen presenters and regulate adaptive immunity. Among DC subtypes plasmacytoid DC （pDC） produce the highest amounts of type I IFN. In addition, pro- and anti-inflammatory cytokines such as IL-12 and IL-10 are induced in DC in response to Toll like receptor （TLR） signaling and upon viral infection. Proteins in the IRF family control many aspects of DC activity. IRF-8 and IRF-4 are essential for DC development. They differentially control the development of four DC subsets. IRF-8^-/- mice are largely devoid of pDC and CD8α^＋ DC, while IRF-4^-/- mice lack CD4^＋ DC. IRF-8^-/-, IRF4^-/-, double knock-out mice have only few CD8α CD4^-DC that lack MHC Ⅱ. IRF proteins also control type Ⅰ IFN induction in DC. IRF-7, activated upon TLR signaling is required for IFN induction not only in pDC, but also in conventional DC （cDC） and non-DC cell types. IRF-3, although contributes to IFN induction in fibroblasts, is dispensable in IFN induction in DC. Our recent evidence reveals that type Ⅰ IFN induction in DC is critically dependent on IRF-8, which acts in the feedback phase of IFN gene induction in DC. Type Ⅰ IFN induction in pDC is mediated by MyD88 dependent signaling pathway, and differs from pathways employed in other cells, which mostly rely on TLR3 and RIG-Ⅰ family proteins. Other pro-inflammatory cytokines are produced in an IRF-5 dependent manner. However, IRF-5 is not required for IFN induction, suggesting the presence of separate mechanisms for induction of type Ⅰ IFN and other pro-inflammatory cytokines. IFN and other cytokines produced by activated DC in turn advance DC maturation and change the phenotype and function of DC. These processes are also likely to be governed by IRF family proteins.展开更多
干扰素基因刺激分子(stimulator of interferon genes,STING)是调控I型干扰素基因表达的重要信号分子之一,在抗感染固有免疫应答中具有重要的作用。研究发现STING参与病毒或细菌dsDNA或RNA刺激引起的固有免疫信号转导途径,STING作为信...干扰素基因刺激分子(stimulator of interferon genes,STING)是调控I型干扰素基因表达的重要信号分子之一,在抗感染固有免疫应答中具有重要的作用。研究发现STING参与病毒或细菌dsDNA或RNA刺激引起的固有免疫信号转导途径,STING作为信号转导接头蛋白能募集TBK1并激活IRF-3(interferon regulatory factor 3,干扰素调节因3)诱导1型IFN的产生,进而调控抗感染固有免疫应答反应。本文就目前STING的研究进展作一综述。展开更多
More than 40%of HIV infections occur via female reproductive tract(FRT)through heterosexual transmission.Epithelial cells that line the female genital mucosa are the first line of defense against HIV-1 and other sexua...More than 40%of HIV infections occur via female reproductive tract(FRT)through heterosexual transmission.Epithelial cells that line the female genital mucosa are the first line of defense against HIV-1 and other sexually transmitted pathogens.These sentient cells recognize and respond to external stimuli by induction of a range of carefully balanced innate immune responses.Previously,we have shown that in response to HIV-1 gp120,the genital epithelial cells(GECs)from upper reproductive tract induce an inflammatory response that may facilitate HIV-1 translocation and infection.In this study,we report that the endometrial and endocervical GECs simultaneously induce biologically active interferon-β(IFNβ)antiviral responses following exposure to HIV-1 that act to protect the epithelial tight junction barrier.The innate antiviral response was directly induced by HIV-1 envelope glycoprotein gp120 and addition of gp120 neutralizing antibody inhibited IFNβproduction.Interferon-βwas induced by gp120 in upper GECs through Toll-like receptor 2 signaling and required presence of heparan sulfate on epithelial cell surface.The induction of IFNβwas dependent upon activation of transcription factor IRF3(interferon regulatory factor 3).The IFNβwas biologically active,had a protective effect on epithelial tight junction barrier and was able to inhibit HIV-1 infection in TZM-bl indicator cells and HIV-1 replication in T cells.This is the first report that recognition of HIV-1 by upper GECs leads to induction of innate antiviral pathways.This could explain the overall low infectivity of HIV-1 in the FRT and could be exploited for HIV-1 prophylaxis.展开更多
文摘To clarify the role of APOBEC3G （A3G） in cellular defense against hepatitis B virus （HBV）, the expression of A3G in normal human liver and the regulation of the A3G expression in hepatoma cell line （HuH-7） were investigated. Expression level of APOBEC3s mRNA in human liver was determined by RT-PCR. HuH-7 and HepG2 cells were treated with various concentrations of IFN-α（0 U/ml, 100 U/ml, 500 U/ml, 1000 U/ml）for 12 h. The mRNA levels were measured by a quantitative RT-PCR, the results were normalized relative to the specimens without IFN-α stimulation. Total protein of HuH-7 cells treated with various concentrations of IFN-α for 48 h was subjected to Western blot analysis. For reporter gene assay, HuH-7 cells were transfected with the reporter plasmids containing IRF- E sites and its mutants with different lengths. Then the cells were treated with or without 1200 U/ml IFN-α for additional 12 h （ 1000 U/ml） after 24 h of transfection, and the cell lysate was prepared and assayed for lueiferase activity. It was found that normal human liver expressed the rnR_NA of A3G. A3G mRNA expression in HuH-7 and HepG2 cells were up-regulated by IFN-α stimulation in a dose-depen- dent manner. Western blot analysis indicated that A3G protein expression was also enhanced by IFN-α stimulation. Sequence analysis showed the existence of putative sites of IFN regulatory factor element （IRF-E） in 5＇ region of A3G gene upstream the initiation eodon. IFN-α stimulation results in 6- to 8- fold increase in lueiferase activity in cells transfeeted with the plasmid containing IRF-E sites of the 5＇ upstream sequences, whereas luciferase activity did not change in cells transfected with the plasmid containing mutant IRF-E sites or without IRF-E sites. As a conclusion, A3G are expressed in normal human liver. A3G expression was up-regulated by IFN-α stimulation in hepatoma cells and could be involved in host defense mechanisms against HBV. IRF-E site in 5＇ region of APOBEC3G gene upstream the initiation codon plays an important role in this process.
文摘Dendritic cells （DC）, although a minor population in hematopoietic cells, produce type I interferons （IFN） and other cytokines and are essential for innate immunity. They are also potent antigen presenters and regulate adaptive immunity. Among DC subtypes plasmacytoid DC （pDC） produce the highest amounts of type I IFN. In addition, pro- and anti-inflammatory cytokines such as IL-12 and IL-10 are induced in DC in response to Toll like receptor （TLR） signaling and upon viral infection. Proteins in the IRF family control many aspects of DC activity. IRF-8 and IRF-4 are essential for DC development. They differentially control the development of four DC subsets. IRF-8^-/- mice are largely devoid of pDC and CD8α^＋ DC, while IRF-4^-/- mice lack CD4^＋ DC. IRF-8^-/-, IRF4^-/-, double knock-out mice have only few CD8α CD4^-DC that lack MHC Ⅱ. IRF proteins also control type Ⅰ IFN induction in DC. IRF-7, activated upon TLR signaling is required for IFN induction not only in pDC, but also in conventional DC （cDC） and non-DC cell types. IRF-3, although contributes to IFN induction in fibroblasts, is dispensable in IFN induction in DC. Our recent evidence reveals that type Ⅰ IFN induction in DC is critically dependent on IRF-8, which acts in the feedback phase of IFN gene induction in DC. Type Ⅰ IFN induction in pDC is mediated by MyD88 dependent signaling pathway, and differs from pathways employed in other cells, which mostly rely on TLR3 and RIG-Ⅰ family proteins. Other pro-inflammatory cytokines are produced in an IRF-5 dependent manner. However, IRF-5 is not required for IFN induction, suggesting the presence of separate mechanisms for induction of type Ⅰ IFN and other pro-inflammatory cytokines. IFN and other cytokines produced by activated DC in turn advance DC maturation and change the phenotype and function of DC. These processes are also likely to be governed by IRF family proteins.
基金by grants from the Canadian Institutes of Health Research(CIHR)Operating Grant FRN 126019(to CK)CIHR Team Grant on Mucosal Immunology of HIV Vaccine Development FRN 138657(to CK)+1 种基金the Ontario HIV Treatment Network(OHTN)Applied HIV Research Chair AHRC 779(to CK)VHF was supported by CIHR Banting Scholarship.
文摘More than 40%of HIV infections occur via female reproductive tract(FRT)through heterosexual transmission.Epithelial cells that line the female genital mucosa are the first line of defense against HIV-1 and other sexually transmitted pathogens.These sentient cells recognize and respond to external stimuli by induction of a range of carefully balanced innate immune responses.Previously,we have shown that in response to HIV-1 gp120,the genital epithelial cells(GECs)from upper reproductive tract induce an inflammatory response that may facilitate HIV-1 translocation and infection.In this study,we report that the endometrial and endocervical GECs simultaneously induce biologically active interferon-β(IFNβ)antiviral responses following exposure to HIV-1 that act to protect the epithelial tight junction barrier.The innate antiviral response was directly induced by HIV-1 envelope glycoprotein gp120 and addition of gp120 neutralizing antibody inhibited IFNβproduction.Interferon-βwas induced by gp120 in upper GECs through Toll-like receptor 2 signaling and required presence of heparan sulfate on epithelial cell surface.The induction of IFNβwas dependent upon activation of transcription factor IRF3(interferon regulatory factor 3).The IFNβwas biologically active,had a protective effect on epithelial tight junction barrier and was able to inhibit HIV-1 infection in TZM-bl indicator cells and HIV-1 replication in T cells.This is the first report that recognition of HIV-1 by upper GECs leads to induction of innate antiviral pathways.This could explain the overall low infectivity of HIV-1 in the FRT and could be exploited for HIV-1 prophylaxis.
