title: Hydrogen peroxide induces La cytoplasmic shuttling and increases hepatitis C virus internal ribosome entry site-dependent translation.
abstract: We have previously shown that physio/pathological levels of hydrogen peroxide (H2O2) stimulate translation from the hepatitis C virus (HCV) internal ribosome entry site (IRES) element in tissue-cultured cells. Here, using in vitro translation, we further show that H2O2 upregulates HCV IRES-dependent mRNA translation and correlates with an increase in intracellular oxidant level. Using Western blotting, immunocytochemistry, microscopy and affinity pulldown, we show that H2O2 stimulates HCV IRES-dependent translation and correlates with nuclear-cytoplasmic shuttling of the La autoantigen, resulting in enhanced binding of cytoplasmic La to HCV IRES RNA. The role of the La protein in H2O2-stimulated IRES-dependent translation is further confirmed by the ability of an anti-La antibody to suppress H2O2-activated IRES-dependent translation in vitro. This is further supported by the ability of an ectopically expressed dominant, negative La mutant protein to suppress H2O2-inducible IRES-mediated translation in Huh7 cells, transiently transfected with a bicistronic reporter and in a sub-genomic replicon cell line resembling a persistent infection. On the other hand, translation from the encephalomyocarditis virus IRES is diminished in the presence of H2O2, suggesting that H2O2 translational responsiveness is a specific property of the HCV IRES and is not a general phenomenon for all viral IRESs. Altogether, these results suggest that HCV adapts to physio/pathological oxidative stress in the host cell by mediating La cytoplasmic shuttling to enhance its IRES-dependent translation.
authors.affiliation: Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
authors.forename: Shiu-Wan
authors.initials: SW
authors.lastname: Chan
mesh_terms: D002460:Cell Line; D004686:Encephalomyocarditis virus; D016174:Hepacivirus / Q000187:drug effects*; D022781:Hepatocytes / Q000187:drug effects / Q000821:virology; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D000067556:Internal Ribosome Entry Sites; D016877:Oxidants / Q000633:toxicity*; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000378:metabolism*; D014779:Virus Replication / Q000187:drug effects
chemical_list: D000067556:Internal Ribosome Entry Sites; C574674:La protein, human; D016877:Oxidants; D010750:Phosphoproteins; D012367:RNA, Viral; D006861:Hydrogen Peroxide