NS5ATP13汇聚并调节HSC活化相关通路在肝纤维化形成与逆转中的作用机制研究

Occurrence and development of liver fibrosis are complex multistep processes which are affected by many factors and genes, but the exact mechanism and effective treatment are still not well-known. Excessive synthesis and abnormal deposition of extracellular matrix of liver cells are the central part in liver fibrosis, which is caused mainly by the activation of hepatic stellate cells (HSC). Thus, how to inhibit proliferation and activation phenotype transformation of HSC, and promote their aging, which plays a key role in the reversal of hepatic fibrosis. NS5ATP13 gene discovered and named in our previous study has been proved to be related to liver fibrosis, while how NS5ATP13 regulates liver fibrosis is still unclear. The study is to explore the correlation between NS5ATP13 and liver fibrotic pathways in different stages of liver fibrosis, the mechanisms of gathering and regulating HSC activation of NS5ATP13 under the exogenous stimuli. The study is also to explore the effects of regulating HSC activation pathways of NS5ATP13 in the liver microenvironment in vivo combined with the mice model. This topic will explore the liver fibrotic study field of NS5ATP13, make the in-depth study of its mechanism, further clarify the related pathogenesis of liver fibrosis, provide the basis for the prevention, diagnosis and treatment of liver fibrosis as well as lay the foundation for the study of new drug treatment targets.

肝纤维化是一种慢性肝损害的病理改变，其发生、发展是一个多因素、多基因和多阶段共同作用的复杂过程。其中，肝星状细胞（HSC）活化导致肝内细胞外间质成分过度合成和异常沉积是肝纤维化发生的主要机制，因此如何抑制HSC活化、促进肝纤维化逆转是研究的关键。前期研究中我们发现并命名了基因NS5ATP13，并证实与肝纤维化相关，但NS5ATP13如何调节肝纤维化仍不清楚。本研究旨在探讨：临床样本中，肝纤维化各时期下NS5ATP13与肝纤维化通路的相关性；HSC中，外源刺激下NS5ATP13汇聚并调节HSC活化相关通路的机制；小鼠模型中，肝脏微环境下深入研究NS5ATP13汇聚并调节HSC活化相关通路在肝纤维化发生和逆转中的作用机制。本课题开拓了NS5ATP13肝纤维化研究领域并对其作用机制深入研究，为进一步明确肝纤维化的相关发病机制以及肝纤维化的预防、诊断和治疗提供依据，为探索新的药物治疗靶点奠定基础。

肝纤维化是对任何病因的慢性肝损伤可逆的创面愈合反应。肝星状细胞(HSCs)的激活是肝纤维形成的关键事件。一般来说，肝星状细胞的持续激活和增殖导致肝纤维化进展，而原发性肝纤维化的逆转机制是激活的肝星状细胞向静止表型的转归和凋亡。HCV NS5A 蛋白反式激活基因 13（NS5ATP13）参与核仁发生和肿瘤发生，但其在肝纤维化和星状细胞活化中的作用尚不清楚。本研究发现，NS5ATP13在肝纤维化组织和TGF-β1诱导的激活人肝星状细胞均上调。此外，无论是否经过TGFβ1处理，NS5ATP13增强了细胞外基质(ECM)的产生和星状细胞活化，都可能涉及TGFβ1/Smad3信号通路。另外，NS5ATP13通过抑制细胞凋亡促进星状细胞增殖。NS5ATP13的激活因素丙肝病毒NS5A部分通过上调TGFβ1和NF-κΒ p65 (RelA)促进NS5ATP13的促纤维作用。与此同时，NS5ATP13参与到NF-kΒ的促纤维形成作用。此外，CK2特异性抑制剂CX-4945降低了NS5ATP13和NF-kΒ的磷酸化以及星状细胞的激活的水平。同时我们发现氧化苦参碱（OMT）可以抑制NS5ATP13，进而抑制肝纤维化的发生。进一步的研究，我们发现OMT 通过下调 NS5ATP13 抑制 AKT/GSK/MTOR 信号通路诱导肝癌细胞HepG2 凋亡。这些发现表明NS5ATP13作为一种促纤维形成因子，提供了一个潜在的抗纤维化的靶点疗法，同时NS5ATP13可以肝纤维化的发生发展以及肿瘤的发生。