Study on the mechanisms of HCV-mediated carcinogenesis

丙型肝炎病毒（HCV）NS5A是一种多功能蛋白，参与HCV的生命周期和HCV诱导的肝脏病理。为了阐明NS5A在HCV发病机制中的作用，我们通过串联亲和纯化寻找与NS5A相互作用的宿主蛋白，并鉴定了一种新的NS5A相互作用蛋白，SET和MYND结构域包含3（SMYD3），一种参与癌细胞增殖的组蛋白甲基转移酶。NS5A与SMYD3的相互作用通过免疫共沉淀、邻位连接测定和共聚焦显微镜证实。NS5A主要与SMYD3共定位于细胞质中。此外，NS5A和SMYD3之间的相互作用可转录激活AGR3，AGR3参与乳腺、前列腺和卵巢肿瘤的发生，属于蛋白质二硫键异构酶家族。总之，这些数据表明NS5A和SMYD3之间的相互作用通过上调AGR3表达引起肝细胞功能障碍。

Hepatitis C Virus (HCV) NS5A is a multifunctional protein involved in HCV life cycle and HCV-induced liver pathologies. To elucidate the role of NS5A in HCV pathogenesis, we searched for host proteins interacting with NS5A by tandem affinity purification and identified a novel NS5A-interacting protein, SET and MYND domain-containing 3 (SMYD3), a histone methyltransferase involved in the proliferation of cancer cells. The interaction of NS5A with SMYD3 was confirmed by co-immunoprecipitation, proximity ligation assay, and confocal microscopy. NS5A predominately colocalized with SMYD3 in the cytoplasm. Moreover, the interaction between NS5A and SMYD3 transcriptionally activated AGR3, which is involved in breast, prostate and ovary tumorigenesis and belongs to the family of protein disulfide isomerases. Taken together, these data suggest that the interaction between NS5A and SMYD3 causes hepatocytic dysfunction through upregulation of AGR3 expression.