title: Hepatitis C virus NS5A hijacks ARFGAP1 to maintain a phosphatidylinositol 4-phosphate-enriched microenvironment.
abstract: Phosphatidylinositol 4-phosphate (PI4P) is well known to be upregulated during hepatitis C virus (HCV) replication. The role of PI4 kinases in HCV has been extensively investigated. Whether the PI4P phosphatase Sac1 is altered by HCV remains unclear. Here, we identified ARFGAP1 to be a novel host factor for HCV replication. We further show that Sac1 interacts with ARFGAP1 and inhibits HCV replication. The elevation of PI4P induced by HCV NS5A is abrogated when the coatomer protein I (COPI) pathway is inhibited. We also found an interaction between NS5A and ARFGAP1. Furthermore, we identified a conserved cluster of positively charged amino acids in NS5A critical for interaction between NS5A and ARFGAP1, induction of PI4P, and HCV replication. Our data demonstrate that ARFGAP1 is a host factor for HCV RNA replication. ARFGAP1 is hijacked by HCV NS5A to remove COPI cargo Sac1 from the site of HCV replication to maintain high levels of PI4P. Our findings provide an additional mechanism by which HCV enhances formation of a PI4P-rich environment.
  
  
  OBJECTIVE
  PI4P is enriched in the replication area of HCV; however, whether PI4P phosphatase Sac1 is subverted by HCV is not established. The detailed mechanism of how COPI contributes to viral replication remains unknown, though COPI components were hijacked by HCV. We demonstrate that ARFGAP1 is hijacked by HCV NS5A to remove COPI cargo Sac1 from the HCV replication area to maintain high-level PI4P generated by NS5A. Furthermore, we identify a conserved cluster of positively charged amino acids in NS5A, which are critical for interaction between NS5A and ARFGAP1, induction of PI4P, and HCV replication. This study will shed mechanistic insight on how other RNA viruses hijack COPI and Sac1.
authors.affiliation: MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China.
authors.forename: Hongyan
authors.initials: H
authors.lastname: Li
authors.forename: Xiaojie
authors.initials: X
authors.lastname: Yang
authors.forename: Guangbo
authors.initials: G
authors.lastname: Yang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Hong
authors.forename: Liya
authors.initials: L
authors.lastname: Zhou
authors.forename: Peiqi
authors.initials: P
authors.lastname: Yin
authors.forename: Yan
authors.initials: Y
authors.lastname: Xiao
authors.forename: Lingyi
authors.initials: L
authors.lastname: Chen
authors.forename: Raymond T
authors.initials: RT
authors.lastname: Chung
authors.forename: Leiliang
authors.initials: L
authors.lastname: Zhang
mesh_terms: D002460:Cell Line; D060833:Cellular Microenvironment / Q000502:physiology*; D017931:DNA Primers / Q000235:genetics; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000235:genetics; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D017361:Viral Nonstructural Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase; D010744:Phosphoric Monoester Hydrolases
chemical_list: D017931:DNA Primers; D020690:GTPase-Activating Proteins; D049452:Green Fluorescent Proteins; D008565:Membrane Proteins; D018129:Phosphatidylinositol Phosphates; D034741:RNA, Small Interfering; D017361:Viral Nonstructural Proteins; C503237:ARFGAP1 protein, human; C037178:phosphatidylinositol 4-phosphate; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C431702:SACM1L protein, human; D010744:Phosphoric Monoester Hydrolases