The molecular mechanisms of SMAD3-mediated coronary disease risk

项目摘要 尽管在治疗方面取得了重大进展，但冠状动脉疾病(CAD)仍然是美国和 全世界。识别风险因素并了解其潜在的生物过程是当务之急 需要开发创新的新疗法。大量的遗传基因座与增加的 全基因组关联研究中冠心病(CAD)的风险。现在需要努力 识别这些基因座上的致病基因，并将它们与特定的细胞过程和信号通路联系起来。 血管壁中的平滑肌细胞(SMC)表达大多数已确定的CAD相关基因 在GWAs。最近，Smad3在15q22.33被确定为冠心病因果关系。发展中 生物学和我们的初步数据表明，Smad3可能改变表型的细胞命运决定 在血管应激状态下，调节血管壁中的SMC。这导致了我们的中心假设 Smad3调控转录网络，抑制保护性SMC表型调节 血管压力。这里描述的一系列实验旨在通过以下方式来表征细胞机制 Smad3表达的哪种扰动调节动脉粥样硬化病变，以及识别 人冠状动脉平滑肌细胞中Smad3调控的遗传程序。AIM 1利用一个 SMC特异性Smad3缺失和并发谱系追踪的小鼠动脉粥样硬化模型。我们会 研究Smad3的表达对SMC细胞命运和导致的疾病解剖的影响。然后我们会申请 单细胞转录图谱检测不同SMC中病变细胞的转录程序 子代，并结合这些数据集来了解SMAD3是如何在SMC中介导CAD风险的 在细胞水平上。目的2应用人冠状动脉平滑肌细胞模型研究血管内皮细胞 Smad3通过全基因组鉴定结合的增强子调控转录程序 Smad3及其转录调控效应。我们还会将这一发现与另一项研究的数据重叠 平滑肌表达的CAD风险相关转录因子TCF21，以加深我们对 SMC转录程序，调节CAD风险。总之，这些研究将显著扩大我们的 了解SMC表达的转录因子SMAD3和TCF21在冠心病中的作用 极大地促进了我们对因果变异调节冠心病风险机制的理解 希望在未来带来新的治疗策略。

Project Summary Despite major advances in therapies, coronary artery disease (CAD) remains the leading killer in the US and worldwide. Identification of risk factors and understanding their underlying biological processes are urgently needed to develop innovative new therapies. Numerous genetic loci have been associated with an increased risk for coronary artery disease (CAD) in genome wide association studies (GWAS). Now efforts are needed to identify causal genes in these loci and link them to specific cellular processes and signaling pathways. Smooth muscle cells (SMC) in the vascular wall express a majority of CAD-associated genes identified in GWAS. Recently, SMAD3 has been identified as the CAD causal association at 15q22.33. Developmental biology as well as our preliminary data suggest SMAD3 may modify cell-fate decisions of phenotypically modulated SMC in the vascular walls in the setting of vascular stress. This led to our central hypothesis that SMAD3 governs a transcriptional network that inhibits protective SMC phenotypic modulation in response to vascular stress. The series of experiments described herein aim to characterize the cellular mechanisms by which perturbation of smooth muscle Smad3 expression modulates atherosclerotic lesions, as well as identify the genetic program regulated by SMAD3 in human coronary artery smooth muscle cells. Aim 1 utilizes a murine atherosclerosis model with SMC-specific deletion of Smad3 and concurrent lineage tracing. We will investigate the effect of Smad3 expression on SMC cell fate and resulting disease anatomy. We will then apply single cell transcriptional profiling of lesion cells to examine the transcriptional program in different SMC progenies, and combine these datasets to understand how CAD risk is mediated by Smad3 specifically in SMC at the cellular level. Aim 2 applies a human coronary artery smooth muscle cell model to study the transcriptional program regulated by SMAD3 through genome-wide identification of enhancers bound by SMAD3 and their transcriptional regulatory effects. We will also overlap the finding with data from another smooth-muscle-expressed CAD-risk-associated transcription factor TCF21, to further our understanding of the SMC transcriptional program that regulates CAD risk. Together, these studies will significantly expand our understanding of the role of transcription factors SMAD3 and TCF21 expressed by SMCs in CAD, and significantly advance our understanding of mechanisms by which causal variation mediates risk for CAD with the hope of leading to novel therapeutic strategies in the future.