Mechanistic link between the anti-HCV effect of interferon gamma and control of viral replication by a ras-MAPK signaling cascade
| Autor: | Jin Lu, Seng-Lai Tan, Madhavi Konduri, Ying Huang, Xinyi Cynthia Chen, Ling Jin, Alexander A. Kolykhalov, Nadejda Fomina |
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| Rok vydání: | 2005 |
| Předmět: |
MAP Kinase Signaling System
viruses MAP Kinase Kinase 2 MAP Kinase Kinase 1 Hepacivirus Viral Nonstructural Proteins Biology Virus Replication Antiviral Agents Interferon-gamma Tumor Cells Cultured Humans Luciferase Protein phosphorylation Replicon Phosphorylation Kinase activity NS5A Hepatology Kinase virus diseases biochemical phenomena metabolism and nutrition Molecular biology digestive system diseases ras Proteins Signal transduction |
| Zdroj: | Hepatology. 43:81-90 |
| ISSN: | 1527-3350 0270-9139 |
| DOI: | 10.1002/hep.21011 |
| Popis: | Interferon-gamma (IFN-γ) exerts potent antiviral activity in the hepatitis C virus (HCV) replicon systems. However, the mechanisms underlying the direct antiviral effect have not been determined. We found that the type II transcriptional response to IFN-γ could be suppressed by inhibition of MEK1/2 kinase activity by MEK1/2 inhibitor U0126 in the hepatoma cell line Huh-7. Using a bicistronic HCV replicon system expressing a luciferase reporter gene in Huh-7 cells (RLuc-replicon), we showed that inhibition of MEK1/2 kinase activity is sufficient to counteract the antiviral activity of IFN-γ. Expression of a constitutive active form of Ras inhibited the luciferase activity of RLuc-replicon, whereas a dominant-negative mutant of Ras enhanced the reporter activity, indicating that the Ras-MAPK pathway has a role in limiting replication of the viral RNA. Consistent with the involvement of the Ras-MAPK pathway, treatment with epidermal growth factor suppressed HCV protein expression in the RLuc-replicon cells, an effect that could be abolished by U0126. Inhibition of MEK1/2 kinase activity correlated with reduced phosphorylation of the HCV NS5A protein and enhanced RLuc-replicon luciferase reporter activity, in line with recent reports that phosphorylation of NS5A negatively modulates HCV RNA replication. Finally, genetic deletion analysis in yeast supported the role of a MEK-like kinase(s) in the regulation of NS5A phosphorylation. In conclusion, the direct anti-HCV effect of IFN-γ in cell culture is, at least in part, mediated through the Ras-MAPK signaling pathway, which possibly involves a direct or indirect modulation of NS5A protein phosphorylation. (HEPATOLOGY 2006;43:81–90.) |
| Databáze: | OpenAIRE |
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