Molecular regulation of the myocardin factors in vascular smooth muscle

描述（由申请人提供）：血管平滑肌细胞（SMC）分化是血管发生和血管生成过程中非常重要的过程，众所周知，SMC表型的改变在几种主要心血管疾病状态（包括动脉粥样硬化、高血压和再狭窄）的进展中起作用。myocardin和myocardin-related transcription factors（MRTFs）是SMC分化的非常重要的调节因子，并且鉴定调节myocardin因子活性的机制对于我们理解SMC特异性转录将是重要的。我们已经确定了组蛋白去甲基化酶，jmjd 1a，作为一种心肌因子结合蛋白，我们的初步数据表明，组蛋白3赖氨酸9（H3 K9）的去甲基化由jmjd 1a调节SMC特异性转录。我们也有初步的数据表明，心肌因子的稳定性是由泛素介导的蛋白体降解，和MURF家族的E3连接酶和LIM结构域蛋白，FHL 2，可能会调节这一途径在SMC。目前的建议的目标是进一步表征这些新的机制，在SMC表型的调节。我们的具体目标如下：1）评估jmjd 1a对SMC表型调节的贡献。我们将测量SMC特异性启动子处的H3 K9甲基化和乙酰化，并敲低jmjd 1a表达，以测试其对SMC特异性基因表达和心肌蛋白因子活性的影响。我们将研究jmjd 1a基因敲除小鼠在发育过程中SMC分化的缺陷和血管损伤后SMC表型调节的改变。2)研究蛋白酶体介导的myocardin因子降解对SMC表型的影响。我们将测量平滑肌细胞中的myocardin和MRTF泛素化，鉴定泛素化的赖氨酸残基，并确定单个MURF家族E3连接酶和FHL 2对myocardin因子稳定性的作用。我们还将研究在Murf 1和Murf 3基因敲除小鼠中心肌因子的稳定性和SMC分化。这些目标的完成应导致更好地了解平滑肌细胞中的心肌因子活性的调节，这可能有助于开发旨在治疗一些心血管疾病的治疗方法。公共卫生相关性：血管平滑肌细胞分化是血管发育过程中一个非常重要的过程，众所周知，这一过程中的改变在几种主要心血管疾病状态（包括动脉粥样硬化、高血压和再狭窄）的进展中发挥作用。我们的建议检查调节平滑肌分化的分子机制，并应有助于确定治疗这些疾病的治疗靶点。

DESCRIPTION (provided by applicant): Vascular smooth muscle cell (SMC) differentiation is a very important process during vasculogenesis and angiogenesis, and it is well recognized that alterations in SMC phenotype play a role in the progression of several prominent cardiovascular disease states including atherosclerosis, hypertension, and restenosis. The myocardin and the myocardin-related transcription factors (MRTFs) are extremely important regulators of SMC differentiation, and the identification of the mechanisms that regulate myocardin factor activity will be important for our understanding of SMC-specific transcription. We have identified the histone demethylase, jmjd1a, as a myocardin factor binding protein and our preliminary data indicate that the demethylation of histone 3 lysine 9 (H3K9) by jmjd1a regulates SMC-specific transcription. We also have preliminary data to suggest that myocardin factor stability is regulated by ubiquitin-mediated proteosomal degradation, and that the MURF family of E3 ligases and the LIM domain protein, FHL2, may regulate this pathway in SMC. The goal of the current proposal is to further characterize these novel mechanisms in the regulation of SMC phenotype. Our specific aims are as follows; 1) to evaluate the contributions of jmjd1a to the regulation of SMC phenotype. We will measure H3K9 methylation and acetylation at the SMC-specific promoters and knock-down jmjd1a expression to test its effects on SMC-specific gene expression and myocardin factor activity. We will examine jmjd1a knockout mice for defects in SMC differentiation during development and for alterations in SMC phenotypic modulation following vessel injury. 2) to study the role of proteosomal-mediated degradation of the myocardin factors on SMC phenotype. We will measure myocardin and MRTF ubiquitination in SMC, identify lysine residues that are ubiquitinylated, and determine the roles of individual MURF family E3 ligases and FHL2 on myocardin factor stability. We will also examine myocardin factor stability and SMC differentiation in Murf1 and Murf3 knockout mice. Completion of these aims should lead to a better understanding of the regulation of myocardin factor activity in SMC which could aid in the development of therapeutics designed to treat a number of cardiovascular diseases. PUBLIC HEALTH RELEVANCE: Vascular smooth muscle cell differentiation is a very important process during the development of blood vessels and it is well recognized that alterations in this process play a role in the progression of several prominent cardiovascular disease states including atherosclerosis, hypertension, and restenosis. Our proposal examines the molecular mechanisms that regulate smooth muscle differentiation and should help to identify therapeutic targets for the treatment of these diseases.