Hepatitis C virus core functions as a suppressor of cyclin-dependent kinase-activating kinase and impairs cell cycle progression
Hepatitis C virus core functions as a suppressor of cyclin-dependent kinase-activating kinase and impairs cell cycle progression
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DOI：
10.1074/jbc.m308560200
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发表时间：
2004-03-19
影响因子：
4.8
通讯作者：
Hayashi, N
中科院分区：
文献类型：
--
作者：
Ohkawa, K;Ishida, H;Hayashi, N
我们通过使用HCV核心表达的稳定转染子研究了丙型肝炎病毒（HCV）核心蛋白如何影响细胞周期谱和细胞周期相关分子。细胞周期特征分析表明HCV核心损害了G(1)到S的转变。在 HCV 核心表达细胞中，E2F 介导的转录、视网膜母细胞瘤蛋白的磷酸化以及细胞周期蛋白依赖性激酶 (CDK) 4 和 CDK2 活性均受到抑制。 G(1)期相关CDK/细胞周期蛋白和各种CDK抑制剂的表达水平基本上不受HCV核心表达的影响。当检查HCV核心对CDK激活激酶（CAK）的影响时，CAK成分CDK7、细胞周期蛋白H和MAT1的表达水平没有受到影响。然而，三元 CAK 复合物的形成、CAK 活性和激活磷酸化的 CDK2 水平均受到 HCV 核心表达的抑制。通过将体外翻译的 HCV 核心蛋白添加到来自细胞的抗 CDK7 免疫沉淀物中，在无细胞系统中进一步评估了 HCV 核心对 CAK 的直接影响。结果表明，HCV 核心导致 MAT1 从 CAK 复合物解离并抑制 CAK 活性。此外，结合测定显示HCV核心针对CDK7。通过免疫染色，它们的相互作用主要发生在细胞核中。总之，HCV 核心蛋白与 CAK 相互作用并作为 CAK 的外在抑制因子发挥作用。这可能是 HCV 核心介导的细胞周期进程抑制的分子基础。我们的研究结果提出了一种关于 HCV 核心介导的细胞周期机制改变的新机制。
We investigated how the hepatitis C virus (HCV) core protein affects the cell cycle profile and cell cycle-related molecules by using the HCV core-expressing stable transfectant. Analysis of the cell cycle profile showed that HCV core impaired G(1) to S transition. The E2F-mediated transcription, phosphorylation of the retinoblastoma protein, and cyclin-dependent kinase (CDK) 4 and CDK2 activities were suppressed in HCV core-expressing cells. The expression levels of G(1) phase-related CDKs/cyclins and various CDK inhibitors were not substantially affected by expression of HCV core. When influences of HCV core on CDK-activating kinase (CAK) were examined, the expression levels of the CAK components, CDK7, cyclin H, and MAT1, were not affected. However, formation of the ternary CAK complex, CAK activity, and the CDK2 level with activating phosphorylation were inhibited by expression of the HCV core. The direct effect of HCV core on CAK was further assessed in the cell-free system by adding the in vitro translated HCV core protein to the anti-CDK7 immunoprecipitate from the cell. The results showed that HCV core led to dissociation of MAT1 from the CAK complex and suppressed the CAK activity. Furthermore, the binding assay revealed that the HCV core was directed against CDK7. Their interaction occurred mainly in the nucleus by the immunostaining. In conclusion, the HCV core protein interacts with CAK and functions as an extrinsic suppressor of CAK. This may be the molecular basis of HCV core-mediated suppression of cell cycle progression. Our findings suggest a novel mechanism concerning HCV core-mediated alteration in the cell cycle machinery.