Epigenetic Regulation of Alcoholic Liver Fibrosis

 描述(申请人提供)：酒精性肝硬变是酒精滥用最普遍和最具破坏性的医学后果，除肝移植外没有有效的治疗方法。肝星状细胞(HSC)的肌成纤维细胞转分化，通常被称为HSC激活，是酒精性肝纤维化的主要机制事件。我们假设，表观遗传调控决定了这种细胞命运调控，并成为最有可能的治疗靶点。为了支持这一假说，我们到目前为止进行的研究揭示了甲基-CpG结合蛋白MeCP2通过以下方式协调表观遗传的HSC激活：1)通过HP1共抑制子的招募和EZH2介导的H3K27二或三甲基化抑制HSC静止基因PPAR-1；2)上调ASH1组蛋白甲基转移酶，进而通过H3K4甲基化诱导纤维化基因如Col1a1、Asma、TIMP1、TGF-β1。[通过组合CHIP-SEQ和RNA-SEQ分析，我们还证明了另一种H3K4甲基转移酶MLL1的显著上调以及MLL1和H3K4me3在具有潜在激活作用的唯一分离的基因集中的共同浓缩。]通过三个具有互补专业知识的领先实验室的国际合作，我们建议扩展这些新的发现，通过追求以下具体目标来进一步确定MeCP2、ASH1和MLL1在HSC激活和酒精性肝纤维化中的因果作用： 通过使用携带MeCP2f/y和Col1a1-CreERT的小鼠来确定可诱导和激活的HSC靶向MeCP2缺陷是否可以防止酒精性肝纤维化的进展；2)了解MeCP2和H3K4 HAT ASH1和MLL1如何在酒精性肝纤维化中导致HSC的表观激活；3)通过使用Col1a2-CreERT：Rosaflx-Stop-Flox-YFP小鼠和基于FACS的酒精性肝纤维化高峰期HSCs分离，来确定是否有表观遗传控制HSC的表型逆转以及“表观遗传记忆”是否与iHSC重新激活的倾向增加有因果关系。]

 DESCRIPTION (provided by applicant): Alcoholic cirrhosis is the most prevalent and devastating medical consequence of alcohol abuse with no efficacious treatment except for liver transplantation. Myofibroblastic transdifferentiation of hepatic stellate cells (HSCs) commonly called HSC activation, constitutes a major mechanistic event in alcoholic liver fibrosis. We hypothesize epigenetic regulation dictates this cell fate regulation and serves as a most plausible therapeutic target. In support of this hypothesis, our research conducted to date revealed the methyl-CpG binding protein MeCP2 orchestrates epigenetic HSC activation via: 1) repression of the HSC quiescence gene Ppar-¿ via recruitment of HP1¿ co-repressor and EZH2-mediated H3K27 di- or tri-methylation; 2) up regulation of ASH1 histone methyltransferase which in turn induces fibrogenic genes such as Col1a1, aSma, Timp1, Tgf-¿1 via H3K4 methylation. [We also demonstrated conspicuous upregulation of another H3K4 methyltrasferase, MLL1 and co-enrichment of MLL1 and H3K4me3 in a uniquely segregated set of genes with potential activation roles by combinatorial ChIP-seq and RNA-seq analyses.] Via international collaboration of three leading laboratories with complementary expertise, we propose to extend these novel findings to further define the causal roles of MeCP2, ASH1, and MLL1 in HSC activation and alcoholic liver fibrosis by pursuing the following specific aims: [1) to determine whether inducible and activated HSC- targeted MeCP2 deficiency prevents the progression of alcoholic liver fibrosis by using mice harboring MeCP2f/y and Col1a1-CreERT; 2) to discover how MeCP2 and the H3K4 HAT ASH1 and MLL1 render epigenetic activation of HSCs in alcoholic liver fibrogenesis; 3) to determine whether there is epigenetic control of HSC phenotype reversion and whether "epigenetic memory" is causally associated with increased re-activation propensity of iHSCs by using Col1a2-CreERT:Rosa26flox-stop-flox-YFP mice and FACS-based isolation of HSCs at the peak of alcoholic liver fibrosis and after resolution from fibrosis. ]