Epigenetic regulation of vascular smooth muscle cell phenotype

血管平滑肌细胞（vascular smooth muscle cell， SMC）的分化是血管发生和血管生成过程中一个非常重要的过程，SMC表型的改变在动脉粥样硬化、高血压和再狭窄等几种主要心血管疾病的进展中起着重要的作用。虽然血清反应因子（SRF）和心肌素因子对SMC分化至关重要，但我们实验室和其他研究人员最近的研究表明，表观遗传机制对SMC特异性基因表达的整体模式也至关重要。事实上，我们发现组蛋白去甲基化酶jmjd1a是一种心肌素因子相互作用蛋白，并表明jmjd1a通过去甲基化SMC特异性附近的H3K9来刺激主动脉SMC培养物中SMC分化标记基因的表达。当前提议的主要目标是仔细检查jmjd1a敲除小鼠对SMC表型的影响，我们将在几种体外和体内SMC表型调节模型中表征H3K9甲基化。H3K9甲基化与DNA甲基化密切相关，有趣的是，smc特异性启动子内的SRF结合区域嵌入在CpG岛中。基于我们的初步数据表明，smc特异性启动子受甲基化调节，Aim 2的目标是确定所涉及的分子机制。最后，为了更好地了解控制SMC表型的全局染色质变化，我们与Jason Lieb和Terry Furrey建立了合作，利用dna酶超敏和甲醛辅助分离调控元件（FAIRE）来“绘制”SMC开放染色质区域。我们已经从人类主动脉SMC培养物中生成了全基因组图谱，并确定了许多以前未检测的启动子区域，这些启动子区域对SMC特异性基因表达可能很重要。Aim 3的目的是测试这些区域是否在体内驱动表达，并确定涉及的染色质修饰因子和转录因子。

DESCRIPTION (provided by applicant): Epigenetic regulation of vascular smooth muscle cell phenotype 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. Although serum response factor (SRF) and the myocardin factors are critical for SMC differentiation, recent studies from our lab and others indicate that epigenetic mechanisms are also critical for the overall pattern of SMC-specific gene expression. Indeed, we identified the histone demethylase, jmjd1a, as a myocardin factor interacting protein and have shown that jmjd1a stimulates SMC differentiation marker gene expression in aortic SMC cultures by demethylating H3K9 near the SMC-specific. A major goal of the current proposal will be to closely examine jmjd1a knock-out mice for effects on SMC phenotype, and we will characterize H3K9 methylation in several in vitro and in vivo models of SMC phenotypic modulation. H3K9 methylation is strongly associated with DNA methylation, and interestingly, the SRF binding regions within the SMC-specific promoters are embedded within CpG islands. Based on our preliminary data indicating that the SMC-specific promoters are regulated by methylation, the goal of Aim 2 is to identify the molecular mechanisms involved. Finally, in an attempt to better understand the global chromatin changes that control SMC phenotype, we have established collaborations with Jason Lieb and Terry Furrey to "map" open chromatin regions in SMC using DNase hypersensitivity and Formaldehyde-Assisted Isolation of Regulatory Elements (FAIRE). We have generated a genome-wide map from human aortic SMC cultures and have identified a number of previously unexamined promoter regions as potentially important for SMC-specific gene expression. The goals of Aim 3 are to test whether these regions drive expression in vivo and to identify the chromatin modifying and transcription factors that are involved.