National Research Laboratory of Hepatitis C Virus, Hallym University, Anyang, South Korea.
Ilsong Institute of Life Science, Hallym University, Anyang, South Korea.
J Virol. 2018 May 14;92(11). doi: 10.1128/JVI.00178-18. Print 2018 Jun 1.
RAD51-associated protein 1 (RAD51AP1) is a member of the multiprotein complexes postulated to carry out RAD51-mediated homologous recombination and DNA repair in mammalian cells. In the present study, we showed that hepatitis C virus (HCV) NS5A directly bound RAD51AP1 and increased the protein level of RAD51AP1 through modulation of the ubiquitin-proteasome pathway. We also demonstrated that RAD51AP1 protein levels were increased in the liver tissues of HCV-infected patients and NS5A-transgenic mice. Importantly, NS5A impaired DNA repair by disrupting the RAD51/RAD51AP1/UAF1 complex and rendered HCV-infected cells more sensitive to DNA damage. Silencing of RAD51AP1 expression resulted in a decrease of viral propagation. We further demonstrated that RAD51AP1 was involved in the assembly step of the HCV life cycle by protecting viral RNA. These data suggest that HCV exploits RAD51AP1 to promote viral propagation and thus that host DNA repair is compromised in HCV-infected cells. Overall, our findings provide mechanistic insight into the pathogenesis of HCV infection. Chronic infection with HCV is the leading cause of hepatocellular carcinoma (HCC). However, the molecular mechanisms underlying HCV-induced HCC are not fully understood. Here we demonstrate that the HCV NS5A protein physically interacts with RAD51AP1 and increases the RAD51AP1 protein level through modulation of the ubiquitin-proteasome pathway. HCV coopts host RAD51AP1 to protect viral RNA at an assembly step of the HCV life cycle. Note that the RAD51 protein accumulates in the cytoplasm of HCV-infected cells, and thus the RAD51/RAD51AP1/UAF1-mediated DNA damage repair system in the nucleus is compromised in HCV-infected cells. Our data may provide new insight into the molecular mechanisms of HCV-induced pathogenesis.
RAD51 相关蛋白 1（RAD51AP1）是假定在哺乳动物细胞中进行 RAD51 介导的同源重组和 DNA 修复的多蛋白复合物的成员。在本研究中，我们表明丙型肝炎病毒（HCV）NS5A 直接与 RAD51AP1 结合，并通过调节泛素-蛋白酶体途径增加 RAD51AP1 的蛋白水平。我们还表明，HCV 感染患者和 NS5A 转基因小鼠的肝组织中 RAD51AP1 蛋白水平增加。重要的是，NS5A 通过破坏 RAD51/RAD51AP1/UAF1 复合物来破坏 DNA 修复，使 HCV 感染的细胞对 DNA 损伤更敏感。沉默 RAD51AP1 的表达导致病毒复制减少。我们进一步表明，RAD51AP1 通过保护病毒 RNA 参与 HCV 生命周期的组装步骤。这些数据表明 HCV 利用 RAD51AP1 来促进病毒的复制，从而使 HCV 感染的细胞中的宿主 DNA 修复受到损害。总的来说，我们的研究结果为 HCV 感染的发病机制提供了机制上的见解。慢性 HCV 感染是肝细胞癌（HCC）的主要原因。然而，HCV 诱导 HCC 的分子机制尚不完全清楚。在这里，我们证明 HCV NS5A 蛋白与 RAD51AP1 相互作用，并通过调节泛素-蛋白酶体途径增加 RAD51AP1 蛋白水平。HCV 利用宿主 RAD51AP1 在 HCV 生命周期的组装步骤中保护病毒 RNA。请注意，RAD51 蛋白在 HCV 感染的细胞中积累在细胞质中，因此 RAD51/RAD51AP1/UAF1 介导的 DNA 损伤修复系统在 HCV 感染的细胞中受到损害。我们的数据可能为 HCV 诱导发病机制的分子机制提供新的见解。
