title: Apolipoprotein E mediates attachment of clinical hepatitis C virus to hepatocytes by binding to cell surface heparan sulfate proteoglycan receptors.
abstract: Our previous studies demonstrated that the cell culture-grown hepatitis C virus of genotype 2a (HCVcc) uses apolipoprotein E (apoE) to mediate its attachment to the surface of human hepatoma Huh-7.5 cells. ApoE mediates HCV attachment by binding to the cell surface heparan sulfate (HS) which is covalently attached to the core proteins of proteoglycans (HSPGs). In the present study, we further determined the physiological importance of apoE and HSPGs in the HCV attachment using a clinical HCV of genotype 1b (HCV1b) obtained from hepatitis C patients and human embryonic stem cell-differentiated hepatocyte-like cells (DHHs). DHHs were found to resemble primary human hepatocytes. Similar to HCVcc, HCV1b was found to attach to the surface of DHHs by the apoE-mediated binding to the cell surface HSPGs. The apoE-specific monoclonal antibody, purified HSPGs, and heparin were all able to efficiently block HCV1b attachment to DHHs. Similarly, the removal of heparan sulfate from cell surface by treatment with heparinase suppressed HCV1b attachment to DHHs. More significantly, HCV1b attachment was potently inhibited by a synthetic peptide derived from the apoE receptor-binding region as well as by an HSPG-binding peptide. Likewise, the HSPG-binding peptide prevented apoE from binding to heparin in a dose-dependent manner, as determined by an in vitro heparin pull-down assay. Collectively, these findings demonstrate that HSPGs serve as major HCV attachment receptors on the surface of human hepatocytes to which the apoE protein ligand on the HCV envelope binds.
authors.affiliation: Department of Microbiology, University of Kentucky College of Medicine, Lexington, Kentucky, United States of America.
authors.forename: Jieyun
authors.initials: J
authors.lastname: Jiang
authors.forename: Xianfang
authors.initials: X
authors.lastname: Wu
authors.forename: Hengli
authors.initials: H
authors.lastname: Tang
authors.forename: Guangxiang
authors.initials: G
authors.lastname: Luo
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology / Q000494:pharmacology; D001057:Apolipoproteins E / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D004305:Dose-Response Relationship, Drug; D005838:Genotype; D057809:HEK293 Cells; D016174:Hepacivirus / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D019812:Heparan Sulfate Proteoglycans / Q000378:metabolism* / Q000494:pharmacology; D006493:Heparin / Q000494:pharmacology; D019763:Heparin Lyase / Q000378:metabolism / Q000494:pharmacology; D006526:Hepatitis C / Q000821:virology; D022781:Hepatocytes / Q000378:metabolism* / Q000821:virology; D054884:Host-Pathogen Interactions; D006801:Humans; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000378:metabolism*; D053585:Virus Attachment / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D001057:Apolipoproteins E; D019812:Heparan Sulfate Proteoglycans; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D010455:Peptides; D011956:Receptors, Cell Surface; D006493:Heparin; D019763:Heparin Lyase