HCVNS5A interacts with p53 and inhibits p53-mediated apoptosis
HCVNS5A interacts with p53 and inhibits p53-mediated apoptosis
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DOI：
10.1038/sj.onc.1205589
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发表时间：
2002-07-18
期刊：
影响因子：
8
通讯作者：
Lee, SD
中科院分区：
文献类型：
--
作者：
Lan, KH;Sheu, ML;Lee, SD
丙型肝炎病毒可导致持续性感染、慢性肝炎和肝细胞癌。丙型肝炎病毒NS5A是丙型肝炎病毒的一种非结构蛋白，被认为在致癌转化中起作用。由于抑癌基因P53在防止肿瘤转化中起重要作用，我们研究了丙型肝炎病毒NS5A对P53的功能影响。采用体内外免疫共沉淀和共聚焦显微镜观察NS5A与P53的相互作用。丙型肝炎病毒NS5A直接与P53结合，并将P53共定位于核周。NS5A通过报告实验以剂量依赖的方式抑制P53的转录反式激活。FLAG-NS5A和FLAG-NS5A稳定细胞株表明，NS5A下调了由P53激活的内源性p21/waf1的表达。用流式细胞仪检测NS5A对外源性P53永久性和瞬时转染型Hep3B细胞中P53介导的细胞凋亡的影响。NS5A可阻断P53诱导的细胞凋亡，其抑制作用与NS5A与P53的结合能力密切相关。此外，在体内，丙型肝炎病毒NS5A蛋白与hTAF(II)32相互作用并共定位，hTAF(II)32是TFIID的一个组成部分，也是P53的重要辅助激活因子。这些结果提示，在丙型肝炎病毒感染过程中，丙型肝炎病毒NS5A与P53和hTAF(II)32相互作用并部分封闭在细胞质中，并抑制P53介导的转录反式激活和细胞凋亡，这可能参与了丙型肝炎病毒感染的肝癌发生。
Hepatitis C virus (HCV) causes a persistent infection, chronic hepatitis and hepatocellular carcinoma. HCV NS5A, one of non-structural proteins of HCV, was suggested to play a role in oncogenic transformation. Since the tumor suppressor p53 is important for preventing neoplastic transformation, we investigated the functional effects of HCV NS5A on p53. In vitro and in vivo coimmunoprecipitation and confocal microscopy were used to determine the interaction of NS5A and p53. HCV NS5A binds directly to p53 and colocalizes p53 in the perinuclear region. NS5A inhibits transcriptional transactivation by p53 in a dose-dependent manner by use of a reporter assay. Down regulation of endogenous p21/waf1 expression, which is activated by p53 in Hep3B cells, by NS5A was demonstrated by using FLAG- and FLAG-NS5A Hep3B stable cell lines. The effect of NS5A on p53-mediated apoptosis was determined by flow cytometry in both NS5A permanently and transiently transfected Hep3B cells with exogenous p53. The p53-induced apoptosis was abrogated by NS5A and the inhibition effect correlates well with the binding ability of NS5A to p53. In addition, HCV NS5A protein interacts with and colocalizes hTAF(II)32, a component of TFIID and an essential coactivator of p53, in vivo. These results suggest that HCV NS5A interacts with and partially sequestrates p53 and hTAF(II)32 in the cytoplasm and suppresses p53-mediated transcriptional transactivation and apoptosis during HCV infection, which may contribute to the hepatocarcinogenesis of HCV infection.