Many mammalian herpes viruses utilize heparan sulfate （HS） moieties present on cell surface proteoglycans as receptors for cell entry, and this process also requires viral glycoprotein C （gC） homologues. However, ...Many mammalian herpes viruses utilize heparan sulfate （HS） moieties present on cell surface proteoglycans as receptors for cell entry, and this process also requires viral glycoprotein C （gC） homologues. However, our understanding of the role of gC in facilitating attachment of other alpha-herpes viruses such as the duck plague virus （DPV） remains preliminary. To study the role of gC during DPV infection, we used a gC-deleted mutant virus （DPV-AgC-EGFP）. Examination of the viral copy number by real-time PCR, as well as time course studies of viral adsorption and proliferation revealed that gC was involved in the viral binding to the cell surface. The affinity of viral glycoproteins （gB-DPV, gC-DPV, and gE-DPV） to HS was assessed using a prokaryotic expression system and HJTrapTM HeparJn HP column chromatography. In addition, to confirm that gC played a role in the interaction between DPV and HS, viruses were treated with the HS analogue heparin and host cells were treated with its inhibitors heparinase prior to exposure to DPV-△gC-EGFP or wild-type strain Chinese virulent duck plague virus （DPV-CHv）. The effects of heparin and heparinase on virus infectivity demonstrated that function of gC on Viral adsorption is independent of interactions between gC and heparin sulfate on cell surface. All in all, this study demonstrated that the gC of DPV can mediate viral adsorption in an HS-independent manner, which distinguish it from the gC of some other alpha-herpes viruses. Future studies will be required to identify the receptors involved in gC protein binding to cells. This work provides us a foundation for further studies of examining the roles of gC in the adsorption during duck plague virus infection.展开更多
Crimean-Congo hemorrhagic fever virus(CCHFV)is a causative agent of serious hemorrhagic diseases in humans with high mortality rates.CCHFV glycoprotein Gc plays critical roles in mediating virus-host membrane fusion a...Crimean-Congo hemorrhagic fever virus(CCHFV)is a causative agent of serious hemorrhagic diseases in humans with high mortality rates.CCHFV glycoprotein Gc plays critical roles in mediating virus-host membrane fusion and has been studied extensively as an immunogen.However,the molecular mechanisms involved in membrane fusion and Gc-specific antibody-antigen interactions remain unresolved largely because structural information of this glycoprotein is missing.We designed a trimeric protein including most of the ectodomain region of Gc from the prototype CCHFV strain,Ib Ar10200,which enabled the cryo-electron microscopy structure to be solved at a resolution of 2.8Å.The structure confirms that CCHFV Gc is a class Ⅱ fusion protein.Unexpectedly,structural comparisons with other solved Gc trimers in the postfusion conformation revealed that CCHFV Gc adopted hybrid architectural features of the fusion loops from hantaviruses and domain Ⅲ from phenuiviruses,suggesting a complex evolutionary pathway among these bunyaviruses.Antigenic sites on CCHFV Gc that protective neutralizing antibodies target were mapped onto the CCHFV Gc structure,providing valuable information that improved our understanding of potential neutralization mechanisms of various antibodies.展开更多
Chronic infection by either hepatitis B virus(HBV)or hepatitis C virus(HCV)share epidemiological characteristics with risks for development of severe complications such as liver cirrhosis and hepatocellular carcinoma....Chronic infection by either hepatitis B virus(HBV)or hepatitis C virus(HCV)share epidemiological characteristics with risks for development of severe complications such as liver cirrhosis and hepatocellular carcinoma.HBV and HCV also share a high genetic variability. Among highly variable regions,viral genes encoding surface proteins(hepatitis B surface antigen,E1/E2 HCV glycoproteins)play key roles in the stimulation of the host-related immune response and viral entry into hepatocytes.Specific segments of HBV envelope proteins(preS1,"a"determinant)are crucial in the entry process into permissive cells.HCV entry is a complex multistep process involving multiple cell cofactors (glycosaminoglycans,low density lipoprotein receptor, SR-B1,CD81,claudin-1,occludin,EGFR,EphA2)in the interaction with HCV E1/E2 envelope glycoproteins.In vitro both viruses can be controlled by antibody-me-diated neutralization targeting viral envelope,also essential in preventing HBV infection in vivo as observed through successful vaccination using HBs antigen.But preventive vaccination and/or therapeutic pressure can influence HBV and HCV variability.For HBV,the patterns of antiviral drug resistance in chronic hepatitis are complex and the original pol/S gene overlap has to be taken into account.Treatment-induced HBV mutations in pol could indeed generate S mutants with subsequent modified antigenicity or increased cancer induction.Variability of HBV and HCV envelope proteins combining high exposure to selective pressures and crucial functional roles require investigation in the context of diagnostic,vaccination and treatment tools.In this editorial a synthesis is performed of HBV and HCV envelope properties at the entry step and as antigenic proteins,and the subsequent clinical impact.展开更多
BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK...BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK)activation could be a new method to reverse MDR.However,the relationship between JNK activity and MDR in HCC cells is unknown.This study aimed to explore the relationship between MDR and JNK in HCC cell lines with different degrees of MDR.METHODS:A MDR human HCC cell line,SMMC-7721/ ADM,was developed by exposing parental cells to gradually increasing concentrations of adriamycin.The MTT assay was used to determine drug sensitivity.Flow cytometry was used to analyze the cell cycle distribution and to measure the expression levels of P-glycoprotein(P-gp)and MDR-related protein(MRP)-1 in these cells.JNK1,JNK2 and JNK3 mRNA expression levels were quantified by real-time PCR.Expression and phosphorylation of JNK1,JNK2,and JNK3 were analyzed by Western blotting.RESULTS:The MDR of SMMC-7721/ADM cells resistant to 0.05 mg/L adriamycin was mainly attributed to the overexpression of P-gp but not MRP1.In addition,these cells had a significant increase in percentage in the S phase,accompanied by a decrease in percentage in the G0/G1 phase,which is likely associated with a reduced ability for cell proliferation and MDR generation.We found that JNK1,JNK2,and JNK3 activities were negatively correlated with the degree of MDR in HCC cells.CONCLUSION:This study suggests that JNK1,JNK2,and JNK3 activities are negatively correlated with the degree of MDR in HCC cells.展开更多
基金supported by the grants from the National Natural Science Foundation of China(31072157)the National Key Technologies R&D Program of China during the 12th Five-Year Plan period(2015BAD12B05)+1 种基金the Foundation of China Agricultural Research System(CARS-43-8)the Major Project of Education Department in Sichuan,China(16ZA0027)
文摘Many mammalian herpes viruses utilize heparan sulfate （HS） moieties present on cell surface proteoglycans as receptors for cell entry, and this process also requires viral glycoprotein C （gC） homologues. However, our understanding of the role of gC in facilitating attachment of other alpha-herpes viruses such as the duck plague virus （DPV） remains preliminary. To study the role of gC during DPV infection, we used a gC-deleted mutant virus （DPV-AgC-EGFP）. Examination of the viral copy number by real-time PCR, as well as time course studies of viral adsorption and proliferation revealed that gC was involved in the viral binding to the cell surface. The affinity of viral glycoproteins （gB-DPV, gC-DPV, and gE-DPV） to HS was assessed using a prokaryotic expression system and HJTrapTM HeparJn HP column chromatography. In addition, to confirm that gC played a role in the interaction between DPV and HS, viruses were treated with the HS analogue heparin and host cells were treated with its inhibitors heparinase prior to exposure to DPV-△gC-EGFP or wild-type strain Chinese virulent duck plague virus （DPV-CHv）. The effects of heparin and heparinase on virus infectivity demonstrated that function of gC on Viral adsorption is independent of interactions between gC and heparin sulfate on cell surface. All in all, this study demonstrated that the gC of DPV can mediate viral adsorption in an HS-independent manner, which distinguish it from the gC of some other alpha-herpes viruses. Future studies will be required to identify the receptors involved in gC protein binding to cells. This work provides us a foundation for further studies of examining the roles of gC in the adsorption during duck plague virus infection.
基金supported by the National Natural Science Foundation of China(31570161)
文摘Crimean-Congo hemorrhagic fever virus(CCHFV)is a causative agent of serious hemorrhagic diseases in humans with high mortality rates.CCHFV glycoprotein Gc plays critical roles in mediating virus-host membrane fusion and has been studied extensively as an immunogen.However,the molecular mechanisms involved in membrane fusion and Gc-specific antibody-antigen interactions remain unresolved largely because structural information of this glycoprotein is missing.We designed a trimeric protein including most of the ectodomain region of Gc from the prototype CCHFV strain,Ib Ar10200,which enabled the cryo-electron microscopy structure to be solved at a resolution of 2.8Å.The structure confirms that CCHFV Gc is a class Ⅱ fusion protein.Unexpectedly,structural comparisons with other solved Gc trimers in the postfusion conformation revealed that CCHFV Gc adopted hybrid architectural features of the fusion loops from hantaviruses and domain Ⅲ from phenuiviruses,suggesting a complex evolutionary pathway among these bunyaviruses.Antigenic sites on CCHFV Gc that protective neutralizing antibodies target were mapped onto the CCHFV Gc structure,providing valuable information that improved our understanding of potential neutralization mechanisms of various antibodies.
文摘Chronic infection by either hepatitis B virus(HBV)or hepatitis C virus(HCV)share epidemiological characteristics with risks for development of severe complications such as liver cirrhosis and hepatocellular carcinoma.HBV and HCV also share a high genetic variability. Among highly variable regions,viral genes encoding surface proteins(hepatitis B surface antigen,E1/E2 HCV glycoproteins)play key roles in the stimulation of the host-related immune response and viral entry into hepatocytes.Specific segments of HBV envelope proteins(preS1,"a"determinant)are crucial in the entry process into permissive cells.HCV entry is a complex multistep process involving multiple cell cofactors (glycosaminoglycans,low density lipoprotein receptor, SR-B1,CD81,claudin-1,occludin,EGFR,EphA2)in the interaction with HCV E1/E2 envelope glycoproteins.In vitro both viruses can be controlled by antibody-me-diated neutralization targeting viral envelope,also essential in preventing HBV infection in vivo as observed through successful vaccination using HBs antigen.But preventive vaccination and/or therapeutic pressure can influence HBV and HCV variability.For HBV,the patterns of antiviral drug resistance in chronic hepatitis are complex and the original pol/S gene overlap has to be taken into account.Treatment-induced HBV mutations in pol could indeed generate S mutants with subsequent modified antigenicity or increased cancer induction.Variability of HBV and HCV envelope proteins combining high exposure to selective pressures and crucial functional roles require investigation in the context of diagnostic,vaccination and treatment tools.In this editorial a synthesis is performed of HBV and HCV envelope properties at the entry step and as antigenic proteins,and the subsequent clinical impact.
基金supported by grants from the Medical Innovation Fundation of Fujian Province(No.2007-CXB-7)the Natural Science Foundation of Fujian Province(No.2009D010)
文摘BACKGROUND:Multidrug resistance(MDR)is extremely common in hepatocellular carcinoma(HCC)and is a major problem in cancer eradication by limiting the efficacy of chemotherapy.Modulation of c-Jun NH2-terminal kinase(JNK)activation could be a new method to reverse MDR.However,the relationship between JNK activity and MDR in HCC cells is unknown.This study aimed to explore the relationship between MDR and JNK in HCC cell lines with different degrees of MDR.METHODS:A MDR human HCC cell line,SMMC-7721/ ADM,was developed by exposing parental cells to gradually increasing concentrations of adriamycin.The MTT assay was used to determine drug sensitivity.Flow cytometry was used to analyze the cell cycle distribution and to measure the expression levels of P-glycoprotein(P-gp)and MDR-related protein(MRP)-1 in these cells.JNK1,JNK2 and JNK3 mRNA expression levels were quantified by real-time PCR.Expression and phosphorylation of JNK1,JNK2,and JNK3 were analyzed by Western blotting.RESULTS:The MDR of SMMC-7721/ADM cells resistant to 0.05 mg/L adriamycin was mainly attributed to the overexpression of P-gp but not MRP1.In addition,these cells had a significant increase in percentage in the S phase,accompanied by a decrease in percentage in the G0/G1 phase,which is likely associated with a reduced ability for cell proliferation and MDR generation.We found that JNK1,JNK2,and JNK3 activities were negatively correlated with the degree of MDR in HCC cells.CONCLUSION:This study suggests that JNK1,JNK2,and JNK3 activities are negatively correlated with the degree of MDR in HCC cells.
