Chromatin Remodeling in Smooth Muscle Myogenesis and Vascular Injury Responses

描述（由申请人提供）：该项目的长期目标是了解平滑肌肌发生过程中平滑肌细胞（SMC）表型变化的分子机制和人类血管疾病的发病机制。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癌症和心脏肥大细胞增殖的控制至关重要。然而，对于在人类血管疾病中如何操纵组蛋白乙酰化控制SMC基因的转录和增殖，人们知之甚少。本应用的目的是确定组蛋白修饰剂，特别是HDAC8，在体外和体内调节SMC基因转录的分子机制。本研究将创新的转基因/敲除小鼠、BAG重组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。本研究的结果不仅填补了我们对hdac转录调控的认识空白，而且进一步加深了我们对SMC肌发生调控的表观遗传机制的认识。大量研究表明，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作用。HDACS是I类HDAC（组蛋白去乙酰化酶）家族的成员，具有组蛋白去乙酰化酶活性。我们的初步结果表明，与其他hdac不同，HDACS作为SMC基因转录的转录激活因子。我们假设HDACS是一种促SMC分化因子，可调节SRF/心肌素和smads介导的SMC转录调节复合物。具体目的是：(1)确定HDACS是否在体外影响SM22位点的组蛋白修饰，以及是否需要HDACS的去乙酰化酶活性来增强SMC调节因子的促肌活性；(2)确定HDACS如何与SMC转录调控网络和TGFpl信号通路相互作用；(3)确定组蛋白去乙酰化酶抑制剂是否影响动脉粥样硬化的发生，以及HDACS如何调节SMC肌生成和损伤性再狭窄的SMC分化。鉴于组蛋白修饰在SMC生长和分化中的重要作用，本研究结果将有助于开发针对影响异常SMC相关人类血管疾病的表观遗传机制的新治疗策略。

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.