Epigenetic regulation of alcoholic liver fibrosis

描述（由申请人提供）：了解肝星状细胞（HSC）的肌纤维母细胞转分化（MTD）的分子机制是开发酒精性肝纤维化新治疗方法的先决条件。我们从多能间充质细胞的细胞命运调控的独特观点接近了这一目标。最后，我们发现“脂肪形成调节”对于HSC静止是必不可少的，并且这种调节的丧失导致MTD。因此，恢复过氧化物酶体增殖物激活受体的表达，MFB中脂肪形成的主要调节因子实现了细胞向静止HSC的表型逆转，并且这种效应通过共转导PPAR？的显性负突变体而完全消除。为了寻找PPAR的机制？抑制MTD，由冢本和曼恩实验室的国际合作披露了两个表观遗传调节剂的主要贡献：甲基CpG结合蛋白MeCP 2，导致HP 1a recmitment甲基化H3 K9在PPAR？启动子;以及多梳抑制复合物2（PRC 2）甲基转移酶EZH 2，其使H3 K27二甲基化和三甲基化作为另一种强大的基因沉默机制。我们还证明了miR 132负控制的丧失是MeCP 2诱导的一种新机制，而MeCP 2诱导反过来又正向调节MTD中EZH 2的表达。拟议的合作研究旨在将这些关于培养激活的HSC中MTD表观遗传调控的突破性发现扩展到酒精性肝纤维化中的MTD。1）确定MeCP 2和EZH 2介导的表观遗传机制在从酒精性肝纤维化小鼠模型分离的活化HSC/MFB中是否明显; 2）确定MeCP 2敲除或特异性靶向活化HSC/MFB的EZH 2抑制剂是否改善酒精性肝纤维化; 3）验证MeCP 2和EZH 2在酒精性肝纤维化中对活化HSC/MFB的表观遗传调控作用，为揭示酒精性肝纤维化的新机制和重要的治疗靶点奠定基础。 公共卫生相关性：这项拟议中的国际合作将披露有关酒精性肝硬化如何发展的新信息，并将在动物模型中测试该疾病的新治疗方法。我们的长期目标是为肝硬化患者提供这种治疗选择。

DESCRIPTION (provided by applicant): The understanding of molecular mechanisms that underlie myofibroblastic transdifferentiation (MTD) of hepatic stellate cells (HSC), is a prerequisite for development of new therapeutic modalities for alcoholic liver cinliosis. We have approached this goal from a unique standpoint of cell fate regulation of pluripotent mesenchymal cells. In this end, we discovered "adipogenic regulation" is essential for HSC quiescence and loss of this regulation results in MTD. As such, restoration ofthe expression of PPAR?, the master regulator of adipogenesis in MFB achieves a phenotypic reversal of the cells to quiescent HSC, and this effect is completely abrogated by co-transduction of a dominant negative mutant of PPAR?. In search for the mechanisms of PPAR? repression in MTD, an international collaboration by Tsukamoto and Mann laboratories disclosed major contributions of two epigenetic regulators: the methyl CpG binding protein MeCP2 which causes HP1a recmitment to methylated H3K9 at PPAR? promoter; and the polycomb repressive complex 2 (PRC2) methyltransferase EZH2 which di- and tri-methylate H3K27 as another mechanism of powerful gene silencing. We also demonstrates a loss ofthe negative control with miR132 as a novel mechanism of MeCP2 induction which in turn positively regulates the expression of EZH2 in MTD. The proposed collaborative research is aimed at extending these ground-breaking findings on epigenetic regulation of MTD shown in culture-activated HSC, to MTD in alcoholic liver fibrogenesis. Toward this goal, the following specific aims will be pursued: 1) to determine whether MeCP2 and EZH2 mediated epigenetic mechanisms are evident in activated HSC/MFB isolated from the mouse model of alcoholic liver fibrosis; 2) to determine whether MeCP2 knockout or a EZH2 inhibitor specifically targeted to activated HSC/MFB ameliorates alcoholic liver fibrosis; 3) to validate MeCP2 and EZH2 mediated epigenetic regulation in activated HSC/MFB in alcoholic liver fibrosis in man. We believe that the proposed study will uncover novel mechanisms of alcoholic liver fibrosis and important therapeutic targets for the disease. PUBLIC HELATH RELEVANCE: The proposed international collaboration will disclose new information conceming how alcohol-induced cirrhosis of the liver develops and will test novel therapeutic approaches for the disease in animal models. It is our long-term goal that such treatment options will be made available for patients suffering from cirrhosis.