title: Hepatitis C virus NS3/4A protein interacts with ATM, impairs DNA repair and enhances sensitivity to ionizing radiation.
abstract: Hepatitis C virus (HCV) infection is frequently associated with the development of hepatocellular carcinomas and non-Hodgkin's B-cell lymphomas. Nonstructural protein 3 (NS3) of HCV possesses serine protease, nucleoside triphosphatase, and helicase activities, while NS4A functions as a cofactor for the NS3 serine protease. Here, we show that HCV NS3/4A interacts with the ATM (ataxia-telangiectasia mutated), a cellular protein essential for cellular response to irradiation. The expression of NS3/4A caused cytoplasmic translocation of either endogenous or exogenous ATM and delayed dephosphorylation of the phosphorylated ATM and gamma-H2AX following ionizing irradiation. As a result, the irradiation-induced gamma-H2AX foci persisted longer in the NS3/4A-expressing cells. Furthermore, these cells showed increased comet tail moment in single-cell electrophoresis assay, indicating increased double-strand DNA breaks. The cells harboring an HCV replicon also exhibited cytoplasmic localization of ATM and increased sensitivity to irradiation. These results demonstrate that NS3/4A impairs the efficiency of DNA repair by interacting with ATM and renders the cells more sensitive to DNA damage. This effect may contribute to HCV oncogenesis.
authors.affiliation: Institute of Molecular Biology, Academia Sinica, Taipei, 115, Taiwan.
authors.forename: Chao-Kuen
authors.initials: CK
authors.lastname: Lai
authors.forename: King-Song
authors.initials: KS
authors.lastname: Jeng
authors.forename: Keigo
authors.initials: K
authors.lastname: Machida
authors.forename: Yi-Sheng
authors.initials: YS
authors.lastname: Cheng
authors.forename: Michael M C
authors.initials: MM
authors.lastname: Lai
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D002460:Cell Line; D003593:Cytoplasm / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D016174:Hepacivirus / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011836:Radiation Tolerance / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012093:Replicon; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000502:physiology*; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology*; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D017346:Protein Serine-Threonine Kinases; D011994:Recombinant Proteins; D025521:Tumor Suppressor Proteins; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; C084422:NS3 protein, hepatitis C virus; D012697:Serine Endopeptidases; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases; C455041:NS4A cofactor peptide, Hepatitis C virus; C576324:ATM protein, human