Yang Chee-Hing, Li Hui-Chun, Ku Tzu-Shan, Wu Pi-Ching, Yeh Yung-Ju, Cheng Ju-Chien, Lin Teng-Yi, Lo Shih-Yen
Institute of medical Sciences, Tzu Chi University, Hualien, Taiwan, ROC.
Department of Biochemistry, School of Medicine, Tzu Chi University, Hualien, Taiwan, ROC.
J Gen Virol. 2017 Sep;98(9):2274-2286. doi: 10.1099/jgv.0.000901. Epub 2017 Aug 31.
Identification of host factors involved in viral replication is critical for understanding the molecular mechanism of viral replication and pathogenesis. Genes differentially expressed in HuH-7 cells with or without a hepatitis C virus (HCV) sub-genomic replicon were screened by microarray analysis. SERPINE1/PAI-1 was found to be down-regulated after HCV infection in this analysis. Down-regulation of SERPINE1/PAI-1 expression at the transcriptional level was verified by the real-time reverse transcriptase (RT)-PCR assay. Reduced SERPINE1/PAI-1 protein secretion was detected in the supernatant of HCV replicon cells and in sera from HCV-infected patients. SERPINE1 gene expression was down-regulated by HCV NS3/4A and NS5A proteins through the transforming growth factor-β (TGF-β) signalling pathway at the transcriptional level. Down-regulated genes in HCV replicon cells could be the factors supressing HCV replication. Indeed, over-expressed PAI-1 inhibited HCV replication but the mechanism is unknown. It has been demonstrated that HCV induces the expression of TGF-β, and TGF-β enhances HCV replication by a not-yet-defined mechanism. SERPINE1/PAI-1 is also known to be potently induced by TGF-β at the transcriptional level through both Smad-dependent and Smad-independent pathways. The exogenously expressed SERPINE1/PAI-1 suppressed the expression of the endogenous SERPINE1 gene at the transcriptional level through the TGF-β signalling but not the Smad pathway. Thus, SERPINE1/PAI-1 could suppress HCV replication possibly by negatively regulating TGF-β signalling. A model is proposed for the interplay betweenthe TGF-β signalling pathway, HCV and SERPINE1/PAI-1 to keep the homeostasis of the cells.
鉴定参与病毒复制的宿主因子对于理解病毒复制和发病机制的分子机制至关重要。通过微阵列分析筛选了在有或没有丙型肝炎病毒（HCV）亚基因组复制子的HuH-7细胞中差异表达的基因。在此分析中发现，HCV感染后SERPINE1/PAI-1表达下调。实时逆转录酶（RT）-PCR检测验证了SERPINE1/PAI-1在转录水平的表达下调。在HCV复制子细胞的上清液和HCV感染患者的血清中检测到SERPINE1/PAI-1蛋白分泌减少。HCV NS3/4A和NS5A蛋白在转录水平通过转化生长因子-β（TGF-β）信号通路下调SERPINE1基因表达。HCV复制子细胞中下调的基因可能是抑制HCV复制的因子。事实上，过表达的PAI-1抑制HCV复制，但其机制尚不清楚。已证明HCV诱导TGF-β的表达，并且TGF-β通过尚未明确的机制增强HCV复制。还已知SERPINE1/PAI-1在转录水平通过Smad依赖和Smad非依赖途径被TGF-β强烈诱导。外源性表达的SERPINE1/PAI-1通过TGF-β信号通路而非Smad途径在转录水平抑制内源性SERPINE1基因的表达。因此，SERPINE1/PAI-1可能通过负调节TGF-β信号通路抑制HCV复制。提出了一个TGF-β信号通路、HCV和SERPINE1/PAI-1之间相互作用的模型，以维持细胞的稳态。
