miR-134在肝纤维化发生发展中的作用及其机制研究

miR-134 is located on human chromosome 14 imprinting gene Dlk1/Dio3 region. Our previous study about the anti hepatocarcinoma effect of miR-134 found that the level of miR-134 in tissues of hepatocellular carcinoma with cirrhosis was significantly lower than that of no cirrhosis specimens, suggesting that miR-134 is closely related with liver cirrhosis. Further study found that the miR-134 level decreased gradually in hepatic fibrogenesis, and the upregulation of miR-134 can inhibit the activation of rat hepatic stellate cells. Moreover, To identify the potential target of miR-134, we searched the Target Scan and found that STAT5b is a potential target gene of miR-134. In addition, STAT5b mRNA level increased during hepatic stellate cell activation. In this study, we will analyse the clinical specimens, investigate the effect of miR-134 in the fibrogenesis and development of hepatic fibrosis. And in-depth study of its mechanism, confirm the role of miR-134 in regulation of STAT5b, clarify the effect and mechanism of miR-134 in anti-fibrosis. By means of intravenous injection of AdmiR-134, definite therapeutic effect on rat liver fibrosis model, provide a new target for clinical thetreatment of liver fibrosis.

miR-134位于人14号染色体印记基因Dlk1/Dio3区域上。前期对miR-134抗肝癌作用的研究中，我们发现肝癌合并肝硬化的组织中miR-134水平显著低于没有合并肝硬化的标本，提示miR-134与肝硬化关系密切。晚近研究发现大鼠肝纤维化过程中miR-134水平逐渐下降，上调miR-134能够抑制大鼠肝星状细胞的活化；此外，采用Target Scan对miR-134靶基因进行筛选，发现STAT5b是miR-134的潜在靶基因，而肝星状细胞活化过程中STAT5b mRNA水平升高。本课题将对临床标本进行分析，明确miR-134在肝纤维化发生发展中的作用，并对其机制深入研究，证实miR-134对STAT5b的调控作用，阐明miR-134抗肝纤维化的作用及其机制；通过制备大鼠肝纤维化模型并尾静脉注射AdmiR-134，明确miR-134对肝纤维化的治疗作用，为肝纤维化的治疗提供新的靶点。

MicroRNA-134（miR-134）位于Dlk1/DiO3印记基因区域上，参与体内多个病理生理过程，在突触形成、胚胎干细胞分化过程中发挥重要作用，还可抑制NSCLC、肾癌、胶质瘤、肝癌等多种肿瘤的增殖、迁移、侵袭及MET过程。本实验室前期研究发现肝癌合并肝硬化患者肝癌组织中miR-134表达显著低于其癌旁组织，且DEN诱导肝纤维化-肝硬化-肝癌模型过程中，肝脏组织中miR-134的表达呈逐渐下降趋势，提示miR-134可能与肝纤维化、肝硬化相关。基于以上研究，本课题通过体内构建BDL、DMN大鼠肝纤维化模型，体外TGF-β刺激肝星状细胞，发现星状细胞活化过程中miR-134表达下降。过表达/抑制miR-134水平可以抑制/促进肝星状细胞活化。靶基因预测及报告基因证实STAT5b及TAB1均是miR-134的直接靶基因，但是在纤维化过程中STAT5b下调和TAB1上调，因此STAT5b并不能介导miR-134的抗肝纤维化作用。而进一步的补救实验提示TAB1具有促进肝纤维的作用，并且miR-134的抗肝纤维化作用部分由TAB1介导。本项目通过对miR-134在肝纤维化发生发展的作用及其机制进行深入研究，为肝纤维化的诊治提供新的思路和策略。