Epigenetic regulation of alcoholic liver fibrosis

描述（由申请人提供）：了解肝星状细胞（HSC）肌成纤维转分化（MTD）的分子机制，是开发酒精性肝纤毛病新治疗方式的先决条件。我们从多能间充质细胞命运调控的独特角度来接近这一目标。最后，我们发现“脂肪生成调控”对HSC的静止至关重要，而这种调控的缺失会导致MTD。因此，恢复PPAR？在MFB中，脂肪形成的主要调控因子实现了细胞向静止HSC的表型逆转，而PPAR?显性负突变体的共转导完全消除了这一效应。寻找PPAR的机制？Tsukamoto和Mann实验室的一项国际合作揭示了两个表观遗传调控因子的主要贡献：甲基CpG结合蛋白MeCP2，它导致HP1a在PPAR？启动子;以及多梳抑制复合体2 （PRC2）甲基转移酶EZH2，其二甲基化和三甲基化H3K27是另一种强大的基因沉默机制。我们还证明了miR132作为MeCP2诱导的一种新的负控制机制的缺失，这反过来又积极调节MTD中EZH2的表达。拟议的合作研究旨在将这些在培养活化的HSC中显示的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。为了实现这一目标，我们将追求以下具体目标：1)确定MeCP2和EZH2介导的表观遗传机制在酒精性肝纤维化小鼠模型中分离的活化HSC/MFB中是否明显；2)确定MeCP2敲除或特异性靶向活化HSC/MFB的EZH2抑制剂是否能改善酒精性肝纤维化；3)验证MeCP2和EZH2介导的活化HSC/MFB在人酒精性肝纤维化中的表观遗传调控。我们相信这项研究将揭示酒精性肝纤维化的新机制和重要的治疗靶点。

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.