Department of Microbiology and Immunology, H. M. Bligh Cancer Research Laboratories, Rosalind Franklin University of Medicine and Science, Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, USA.
Virology. 2011 Apr 10;412(2):284-96. doi: 10.1016/j.virol.2010.12.051. Epub 2011 Feb 5.
In this study, we demonstrated the molecular mechanisms of TGF-β1 induction as well as proteolytic activation in HCV (JFH-1)-infected cells. Our studies showed the synthesis and secretion of TGF-β1 in HCV-infected cells which was reduced in the presence of Ca(2+) chelators, an inhibitor of mitochondrial Ca(2+) uptake, and antioxidants. We also showed that the expression of HCV NS proteins NS3/4A, and NS5A can induce TGF-β1 by cell-based luciferase assay. Furthermore, mutational analysis revealed that the functionally active protease domain of NS3 and N-terminus domain of NS5A are required for TGF-β1 activity. Using siRNA approach we demonstrated that HCV-induced furin and thrombospondin-1 (TSP-1) are involved in the proteolytic activation of TGF-β1. Our results also suggest that TGF-β1 positively regulates HCV RNA replication. Collectively, these observations provide insight into the mechanism of TGF-β1 activation, which likely manifest in liver fibrosis associated with hepatitis C infection.
在这项研究中，我们展示了 TGF-β1 在 HCV（JFH-1）感染细胞中的诱导和蛋白水解激活的分子机制。我们的研究表明，TGF-β1 在 HCV 感染的细胞中合成和分泌，而在存在 Ca2+螯合剂、线粒体 Ca2+摄取抑制剂和抗氧化剂的情况下，其分泌减少。我们还表明，HCV NS 蛋白 NS3/4A 和 NS5A 的表达可以通过基于细胞的荧光素酶测定诱导 TGF-β1。此外，突变分析表明，NS3 的功能活性蛋白酶结构域和 NS5A 的 N 末端结构域是 TGF-β1 活性所必需的。我们使用 siRNA 方法证明，HCV 诱导的弗林蛋白酶和血小板反应蛋白-1（TSP-1）参与了 TGF-β1 的蛋白水解激活。我们的结果还表明，TGF-β1 正向调节 HCV RNA 复制。总的来说，这些观察结果为 TGF-β1 激活的机制提供了深入的了解，这可能与丙型肝炎感染相关的肝纤维化有关。
