Reg of SM22 Alpha Transcription in Smooth Muscle Cells

描述（申请人摘要）：血管平滑肌的能力 细胞（SMCs）调节其对动脉损伤的反应已经被牵连 在血管增生综合征的发病机制中， 动脉粥样硬化和冠状动脉介入治疗后再狭窄。我们有 利用SMC特异性小鼠SM 22 a启动子作为模型系统来阐明 控制VSMC发育和分化的转录程序。 在该奖项的初始供资周期，顺式作用元件和 控制SM 22 a启动子表达的反式作用因子是 定义了SM 22 a启动子中的两个核蛋白结合位点（SME- 1和 SME-4），其含有结合 特别是MADS盒转录因子SRF。值得注意的是， SME-1或SME-4的多聚化拷贝是必要的并且足以 将LacZ报告基因的活性限制于转基因小鼠的动脉SMC。 这些数据使我们假设SRF与其他潜在的 新的转录激活因子（和潜在的抑制因子）， SMC特异性基因表达和SMC表型。的总体目标 建议的研究是阐明SRF依赖的分子基础， 在动脉SMC中的转录。这些研究的具体目标是： 检查SMC中SRF-CArG盒活性的分子基础，ii）检查 调节SM 22 a启动子活性的蛋白质-蛋白质缔合， 特别关注SRF/同源框蛋白相互作用的SMC，iii） 研究LIMK- 1介导的SM 22 cz激活的信号通路 iv）检查SRF-/- ES细胞促进SRF-/- ES细胞表达的能力。 SRF-/- -C57 BL/6嵌合小鼠中的SMC谱系，并定义下游SMC和 胚胎中SRF调控的中胚层基因。综合来看，这些研究 将阐明转录程序和一个重要的信号通路 调节SM 22 a基因在SMC中的表达。因为CArG 包含框的元素已在多个其他SMC特定 这些研究将提供对分子生物学的基本见解。 控制SMC分化和调节血管SMC的机制 表型

DESCRIPTION (Applicant's abstract): The capacity of vascular smooth muscle cells (SMCs) to modulate their response to arterial injury has been implicated in the pathogenesis of vascular proliferative syndromes including atherosclerosis and restenosis following coronary intervention. We have utilized the SMC-specific mouse SM22a promoter as a model system to elucidate the transcriptional programs that control VSMC development and differentiation. During the initial funding cycle of this award, the cis-acting elements and trans-acting factors that control expression of the SM22a promoter were defined. Two nuclear protein binding sites in the SM22a promoter (SME- 1 and SME-4) were identified which contain consensus CArU boxes that bind specifically to the MADS box transcription factor, SRF. Remarkably, a multimerized copy of either SME-l or SME-4 is necessary and sufficient to restrict activity of a LacZ reporter gene to arterial SMCs in transgenic mice. These data lead us to hypothesize that SRF, in concert with other potentially novel transcriptional activators (and potentially repressors), regulates SMC-specific gene expression and SMC phenotype. The overall goal of the proposed studies is to elucidate the molecular basis of SRF-dependent transcription in arterial SMCs. The specific aims of these studies are to: i) Examine the molecular basis of SRF-CArG box activity in SMCs, ii) Examine protein-protein associations that modulate activity of the SM22a promoter in SMCs with particular attention on SRF/homeobox protein interactions, iii) Examine signaling pathways underlying LIMK- 1-mediated activation of the SM22cz promoter, and iv) Examine the capacity of SRF-/- ES cells to contribute to the SMC lineage(s) in SRF-/- -C57BL/6 chimenc mice and define downstream SMC and mesodermal genes regulated by SRF in the embryo. Taken together, these studies will elucidate the transcriptional program and an important signaling pathway that modulates expression of the SM22a gene in SMCs. Because CArG box-containing elements have been identified in multiple other SMC-specific genes these studies will provide fundamental insights into the molecular mechanisms that control SMC differentiation and the modulation of vascular SMC phenotype.