title: Amphipathic α-helices in apolipoproteins are crucial to the formation of infectious hepatitis C virus particles.
abstract: Apolipoprotein B (ApoB) and ApoE have been shown to participate in the particle formation and the tissue tropism of hepatitis C virus (HCV), but their precise roles remain uncertain. Here we show that amphipathic α-helices in the apolipoproteins participate in the HCV particle formation by using zinc finger nucleases-mediated apolipoprotein B (ApoB) and/or ApoE gene knockout Huh7 cells. Although Huh7 cells deficient in either ApoB or ApoE gene exhibited slight reduction of particles formation, knockout of both ApoB and ApoE genes in Huh7 (DKO) cells severely impaired the formation of infectious HCV particles, suggesting that ApoB and ApoE have redundant roles in the formation of infectious HCV particles. cDNA microarray analyses revealed that ApoB and ApoE are dominantly expressed in Huh7 cells, in contrast to the high level expression of all of the exchangeable apolipoproteins, including ApoA1, ApoA2, ApoC1, ApoC2 and ApoC3 in human liver tissues. The exogenous expression of not only ApoE, but also other exchangeable apolipoproteins rescued the infectious particle formation of HCV in DKO cells. In addition, expression of these apolipoproteins facilitated the formation of infectious particles of genotype 1b and 3a chimeric viruses. Furthermore, expression of amphipathic α-helices in the exchangeable apolipoproteins facilitated the particle formation in DKO cells through an interaction with viral particles. These results suggest that amphipathic α-helices in the exchangeable apolipoproteins play crucial roles in the infectious particle formation of HCV and provide clues to the understanding of life cycle of HCV and the development of novel anti-HCV therapeutics targeting for viral assembly.
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Takasuke
authors.initials: T
authors.lastname: Fukuhara
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Masami
authors.initials: M
authors.lastname: Wada
authors.affiliation: Department of Infection Metagenomics, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Shota
authors.initials: S
authors.lastname: Nakamura
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Chikako
authors.initials: C
authors.lastname: Ono
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Mai
authors.initials: M
authors.lastname: Shiokawa
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Satomi
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Motomura
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Okamoto
authors.affiliation: DNA-Chip Developmental Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Okuzaki
authors.affiliation: Department of Immunoparasitology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Laboratory of Molecular Genetics, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors.forename: Izumu
authors.initials: I
authors.lastname: Saito
authors.affiliation: Department of Virology II, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Takaji
authors.initials: T
authors.lastname: Wakita
authors.affiliation: Department of Gastroenterology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Koike
authors.affiliation: Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan.
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Matsuura
mesh_terms: D001054:Apolipoproteins A / Q000502:physiology; D001055:Apolipoproteins B / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D001056:Apolipoproteins C / Q000502:physiology; D001057:Apolipoproteins E / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D006528:Carcinoma, Hepatocellular / Q000473:pathology / Q000821:virology; D045744:Cell Line, Tumor; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D055786:Gene Knockout Techniques; D016174:Hepacivirus / Q000472:pathogenicity* / Q000502:physiology; D006801:Humans; D008113:Liver Neoplasms / Q000473:pathology / Q000821:virology; D017433:Protein Structure, Secondary / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D014771:Virion / Q000472:pathogenicity* / Q000502:physiology; D014779:Virus Replication / Q000502:physiology
chemical_list: D001054:Apolipoproteins A; D001055:Apolipoproteins B; D001056:Apolipoproteins C; D001057:Apolipoproteins E; D034741:RNA, Small Interfering