Chromatin Remodeling in Smooth Muscle Myogenesis and Vascular Injury Responses

描述(由申请者提供)：该项目的长期目标是了解调节平滑肌细胞(SMC)表型变化的分子机制，这些变化在肌肉发生过程中以及在人类血管疾病的发病机制中。最近广泛的生化和遗传学研究提供了大量证据表明，组蛋白乙酰化和去乙酰化的平衡对于控制癌症和心脏肥大的细胞增殖至关重要。然而，在人类血管疾病中，操纵组蛋白乙酰化是如何控制SMC基因转录和增殖的，我们知之甚少。这项应用的目的是确定组蛋白修饰物，特别是HDAC8，在体外和体内调节SMC基因转录的分子机制。这项研究将创新的转基因/基因敲除小鼠、BAG重组工程和生物信息学工具整合到经典的生化、分子和发育生物学方法中。这项研究的结果不仅填补了我们对HDACs转录调控方面的一个空白，而且进一步加深了我们对SMC肌发生的表观遗传学机制的了解。广泛的研究表明，组蛋白乙酰化和去乙酰化的动态变化在基因转录和细胞增殖中起着重要的作用。组蛋白脱乙酰酶是组蛋白脱乙酰酶I类家族的成员，具有组蛋白脱乙酰酶活性。我们的初步结果表明，与其他HDAC不同，HDAC作为SMC基因转录的转录激活剂。我们假设HDACs是一种促SMC分化因子，调节SRF/Myocardin和Smads介导的SMC转录调控复合体。这些研究的具体目的是：(1)确定HDACs是否影响SM22位点的组蛋白修饰，以及HDACs的脱乙酰酶活性是否需要增强SMC调节器的促肌生成活性；(2)确定HDACs如何与SMC转录调控网络和TGFp1信号通路相互作用；(3)确定组蛋白脱乙酰酶抑制物是否影响动脉粥样硬化的形成；以及HDACs如何在SMC肌肉发生和损伤诱导的再狭窄中调节SMC分化。鉴于组蛋白修饰在SMC生长和分化中的重要作用，本研究的结果将有助于开发针对影响SMC相关异常血管疾病的表观遗传机制的新的治疗策略。

DESCRIPTION (provided by applicant): The long-term goal of this project is to understand the molecular mechanisms that regulate smooth muscle cell (SMC) phenotypic changes during smooth muscle myogenesis and in the pathogenesis of human vascular diseases. Recent extensive biochemical and genetic studies have provided substantial evidence showing that the balance of histone acetylation and deacetylation is crucial to the control of cell proliferation in cancer and cardiac hypertrophy. However, little is known about how manipulating histone acetylation controls SMC gene transcription and proliferation in human vascular diseases. The goal of this application is to determine the molecular mechanisms whereby histone modifiers, especially HDAC8, regulate SMC gene transcription both in vitro and in vivo. This study integrates innovative transgenic/knockout mice, BAG recombineering and bioinformatics tools into classic biochemical, molecular and developmental biology approaches. The results of this study will not only fill a gap in our understanding of HDACs in transcriptional regulation, but also further our knowledge of epigenetic mechanisms in regulating SMC myogenesis^ Extensive studies demonstrate that the dynamic changes of histone acetylation and deacetylation play important roles in gene transcription and cell proliferation. HDACS is a member of the class I HDAC (histone deacetylase) family, and possesses histone deacetylase activities. Our preliminary results show that HDACS, unlike other HDACs, acts as a transcriptional activator for SMC gene transcription. We hypothesize that HDACS is a pro-SMC differentiation factor that modulates SRF/Myocardin and SmadS-mediated SMC transcriptional regulatory complexes. The specific aims are: (1) to determine whether HDACS affects histone modification at the SM22 locus in vitro, and whether the deacetylase activity of HDACS is required to enhance the pro-myogenic activities of SMC regulators; (2) to determine how HDACS interacts with the SMC transcriptional regulatory network and TGFpl signal pathway; (3) to determine whether histone deacetylase inhibitors affect atherogenesis and how HDACS modulates SMC differentiation in SMC myogenesis and in injury-induced restenosis in vivo. Given the important roles of histone modification in SMC growth and differentiation, the results of this study will contribute significantly towards developing novel therapeutical strategies targeted at the epigenetic mechanisms affecting the abnormal SMC-associated human vascular diseases.