title: RacGTPase-activating protein 1 interacts with hepatitis C virus polymerase NS5B to regulate viral replication.
abstract: Hepatitis C virus (HCV) is a positive-strand RNA virus responsible for chronic liver disease and hepatocellular carcinoma (HCC). RacGTPase-activating protein 1 (RacGAP1) plays an important role during GTP hydrolysis to GDP in Rac1 and CDC42 protein and has been demonstrated to be upregulated in several cancers, including HCC. However, the molecular mechanism leading to the upregulation of RacGAP1 remains poorly understood. Here, we showed that RacGAP1 levels were enhanced in HCV cell-culture-derived (HCVcc) infection. More importantly, we illustrated that RacGAP1 interacts with the viral protein NS5B in mammalian cells. The small interfering RNA (siRNA)-mediated knockdown of RacGAP1 in human hepatoma cell lines inhibited replication of HCV RNA, protein, and production of infectious particles of HCV genotype 2a strain JFH1. Conversely, these were reversed by the expression of a siRNA-resistant RacGAP1 recombinant protein. In addition, viral protein NS5B polymerase activity was significantly reduced by silencing RacGAP1 and, vice versa, was increased by overexpression of RacGAP1 in a cell-based reporter assay. Our results suggest that RacGAP1 plays a crucial role in HCV replication by affecting viral protein NS5B polymerase activity and holds importance for antiviral drug development.
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Ming-Jhan
authors.initials: MJ
authors.lastname: Wu
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan, Taiwan.
authors.forename: Po-Yuan
authors.initials: PY
authors.lastname: Ke
authors.affiliation: Department of Biochemistry and Molecular Biology, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Research Center for Emerging Viral Infections, College of Medicine, Chang Gung University, Taoyuan, Taiwan; Department of Medical Research, Chang Gung Memorial Hospital, Taoyuan, Taiwan. Electronic address: jimtong@mail.cgu.edu.tw.
authors.forename: Jim-Tong
authors.initials: JT
authors.lastname: Horng
mesh_terms: D000494:Allosteric Regulation; D000998:Antiviral Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D055808:Drug Discovery; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020690:GTPase-Activating Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D005838:Genotype; D057809:HEK293 Cells; D016174:Hepacivirus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D054884:Host-Pathogen Interactions / Q000502:physiology; D006801:Humans; D034741:RNA, Small Interfering / Q000235:genetics; D012093:Replicon; D017361:Viral Nonstructural Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D034741:RNA, Small Interfering; D017361:Viral Nonstructural Proteins; C115995:mgcRacGAP; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase
keywords: Cell-based reporter assay; Hepatitis C virus; NS5B polymerase; RacGTPase-activating protein 1