乙型肝炎病毒剪接蛋白与TGFβ1I1相互作用在肝硬化、肝癌过程中的致病机制

The hepatitis B spliced protein (HBSP) encoded by a 2.2 kb singly spliced defective HBV genome (spliced between positions 2447 nt and 489 nt) has been shown to play an important role in hepatopathogenesis, yet the exact mechanisms remain to be fully elucidated. Transforming growth factor β1-induced protein (TGFβ1I1), involved in liver cirrhosis through the regulation of TGFβ1 autocrine and androgen-dependent tumorigenesis through enhancing the transcription of androgen-induced downstream genes, was previously identified as an intracellular interacting partner of hepatitis B spliced protein (HBSP) by the cytoplasmic yeast two-hybrid screening and the interaction was demonstrated by GST pull-down and in vivo co-immunoprecipitation. In the present study, the interaction between HBSP and TGFβ1I1, and the respective binding regions on this basis will be clarified by mammalian two-hybrid assay. To investigate the potential role of HBSP-TGFβ1I1 interaction in the hepatopathogenesis of liver cirrhosis and hepatocellular carcinoma, the influences of HBSP-TGFβ1I1 interaction on the TGFβ1 autocrine of hepatocytes and sustained activation of stellate cells, as well as the androgen receptor activity and TGFβ1I1-mediated androgen-related tumorigenesis, will be explored.Our study will be helpful to the better understanding of the mechanisms of HBV-related cirrhosis and high prevalence of the male hepatocellular carcinoma.

乙型肝炎病毒剪接蛋白（hepatitis B spliced protein，HBSP）与HBV致病性密切相关，但具体机制未明。我们通过酵母双杂交发现HBSP可与转化生长因子β1诱导蛋白（transforming growth factor beta 1 induced transcript 1，TGFβ1I1) 相互作用。TGFβ1I1通过调控TGFβ1自分泌促进肝硬化，并通过增强雄激素诱导的下游基因转录促进雄激素依赖的肿瘤发生。因此，HBSP与TGFβ1I1相互作用可能具有重要的致病意义。为此，本研究首先进一步确定HBSP与TGFβ1I1相互作用并明确各自结合区域，在此基础上，探讨二者相互作用对肝细胞自分泌TGFβ1及诱导星状细胞持续活化的影响，以及HBSP对TGFβ1I1介导的雄激素受体活性及雄激素诱导的肿瘤发生的影响。本研究将加深对HBV相关性肝硬化及男性肝细胞癌多发机制的了解。

乙型肝炎病毒剪接蛋白（hepatitis B spliced protein，HBSP）广泛存在于慢性乙型肝炎患者的血清或肝组织中，与HBV致病性密切相关。转化生长因子β1诱导蛋白（transforming growth factor beta 1 induced transcript 1，TGFβ1I1)与TGFβ1诱导的上皮间质转化有关。本研究通过免疫共沉淀、GST-Pulldown、哺乳动物双杂交实验，成功验证了前期研究通过酵母双杂交筛选获得的HBSP与TGFβ1I1 的相互作用，并明确二者相互作用的位点。通过以TGFβ1诱导HBSP过表达的慢病毒细胞株，证实HBSP与TGFβ1I1 的相互作用通过TGFβ1/Smad信号通路促进了肝癌细胞株的上皮间质转化（EMT），导致肝脏星形细胞的活化，可能与肝纤维化进程有关。本研究对深化乙型肝炎病毒剪接蛋白致病机制的认识具有重要意义。