Hepatitis C virus NS5A protein impairs TNF-mediated hepatic apoptosis, but not by an anti-FAS antibody, in transgenic mice
Hepatitis C virus NS5A protein impairs TNF-mediated hepatic apoptosis, but not by an anti-FAS antibody, in transgenic mice
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DOI：
10.1006/viro.2001.1309
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发表时间：
2002-03-01
期刊：
影响因子：
3.7
通讯作者：
Ray, RB
中科院分区：
文献类型：
--
作者：
Majumder, M;Ghosh, AK;Ray, RB
丙型肝炎病毒（HCV）是世界范围内慢性肝炎的主要病因，并可能导致肝细胞癌的发展。然而，HCV发展为慢性肝炎或肝癌的机制尚不清楚。在本研究中，我们研究了非结构蛋白5A （NS5A）对TNF-和fas介导的转基因小鼠肝脏细胞凋亡的影响。为此，在肝脏特异性apoE启动子的控制下，通过克隆HCV NS5A基因组区域来产生转基因小鼠。转基因动物在表型上与其正常窝鼠相似，并且在8-12周龄时没有表现出可检测的肝脏组织学变化。腹腔注射重组TNF诱导正常小鼠肝损伤及细胞凋亡。相比之下，表达NS5A蛋白的转基因小鼠在注射TNF后可防止肝细胞凋亡。然而，与正常窝鼠相比，注射抗fas抗体对转基因小鼠的肝细胞凋亡没有显著影响。这些结果表明TNF和抗fas抗体对表达NS5A的转基因小鼠有明显的影响。我们随后研究了NS5A在参与这两种细胞因子介导的凋亡的信号通路中的作用。通过下拉实验、共免疫沉淀和共定位实验观察NS5A与TRADD之间的物理关联。此外，NS5A阻止TRADD和FADD之间的关联，并阻断TRADD介导的NF-kappaB激活。综上所述，我们的研究结果表明NS5A通过干扰上游信号转导通路损害tnf介导的细胞凋亡，并可能在hcv介导的发病机制中发挥作用。(C) 2002 Elsevier Science （USA）。
Hepatitis C virus (HCV) is a major etiologic agent of chronic hepatitis worldwide and may lead to the development of hepatocellular carcinoma. However, the mechanism of development of chronic hepatitis or hepatocarcinogenesis by HCV remains unclear. In the present study, we have investigated the effect of nonstructural protein 5A (NS5A) on TNF- and Fas-mediated apoptosis in the liver of transgenic mice. For this purpose, transgenic mice were generated by targeting the HCV NS5A genomic region cloned under the control of a liver-specific apoE promoter. The transgenic animals were phenotypically similar to their normal littermates and did not exhibit a detectable histological change in the liver at 8-12 weeks of age. Intraperitoneal injection of recombinant TNF induced hepatic injury and apoptosis in normal mice. In contrast, transgenic mice expressing NS5A protein were protected against hepatic apoptosis after injection of TNF. However, injection of anti-Fas antibody into transgenic mice did not significantly influence hepatic apoptosis compared to the normal littermates. These results suggested distinct effects of TNF and anti-Fas antibody in transgenic mice expressing NS5A. We subsequently investigated the effect of NS5A in signaling pathways involved in these two cytokine-mediated apoptosis. A physical association between NS5A and TRADD was observed by pull-down assay, coimmunoprecipitation, and colocalization experiments. Furthermore, NS5A prevented the association between TRADD and FADD and blocked TRADD-mediated NF-kappaB activation. Together, our results suggest that NS5A impairs TNF-mediated apoptosis by interfering upstream of the signal transduction pathway and may play a role in HCV-mediated pathogenesis. (C) 2002 Elsevier Science (USA).