College of Life Sciences, State Key Laboratory of Virology, Wuhan University, Wuhan, Hubei 430072, China.
Virology. 2013 Jan 20;435(2):385-94. doi: 10.1016/j.virol.2012.10.025. Epub 2012 Nov 5.
Hepatitis C virus (HCV) infection often causes long-term persistent hepatitis, which eventually leads to liver cirrhosis and hepatocellular carcinoma. HCV-encoded NS3/4A protease plays an important role in HCV immune evasion by cleaving key adapter proteins VISA and TRIF of the RIG-I-like receptors and Toll-like receptors mediated interferon (IFN) induction pathways. To further understand the roles of NS3/4A in HCV life cycle, we identified DDB1 as a cellular substrate of NS3/4A protease by biochemical purification and mass spectrometry analysis. NS3/4A interacted with DDB1 and cleaved DDB1 in HCV-infected cells. Mutagenesis indicated that NS3/4A cleaved DDB1 at the residue of C378. Overexpression of DDB1 potentiated HCV replication, whereas knockdown of DDB1 dramatically inhibited HCV replication. Furthermore, our data indicated that the cleavage of DDB1 by NS3/4A protease was required for HCV replication. Our findings suggest that DDB1 is a cellular substrate of NS3/4A required for HCV replication and provide new insight into the interaction between HCV and host cells.
丙型肝炎病毒 (HCV) 感染常导致长期持续性肝炎，最终导致肝硬化和肝细胞癌。HCV 编码的 NS3/4A 蛋白酶通过切割 RIG-I 样受体和 Toll 样受体介导的干扰素 (IFN) 诱导途径的关键衔接蛋白 VISA 和 TRIF，在 HCV 免疫逃逸中发挥重要作用。为了进一步了解 NS3/4A 在 HCV 生命周期中的作用，我们通过生化纯化和质谱分析鉴定了 DDB1 作为 NS3/4A 蛋白酶的细胞底物。NS3/4A 在 HCV 感染的细胞中与 DDB1 相互作用并切割 DDB1。突变分析表明，NS3/4A 在 C378 残基处切割 DDB1。DDB1 的过表达增强了 HCV 的复制，而 DDB1 的敲低则显著抑制了 HCV 的复制。此外，我们的数据表明，NS3/4A 蛋白酶对 DDB1 的切割是 HCV 复制所必需的。我们的研究结果表明，DDB1 是 HCV 复制所必需的 NS3/4A 的细胞底物，为 HCV 与宿主细胞之间的相互作用提供了新的见解。
