TCF21 is a causal coronary artery disease gene that modulates coronary smooth muscle phenotypic transition via epigenetic mechanisms

项目摘要 超过161个基因位点已通过基因组与冠状动脉疾病（CAD）相关 广泛关联研究（GWAS）由CARDIOGRAMplusC 4D联盟进行。但尽管 这种对冠状动脉疾病的理解的进步， 尚未进入临床阶段。在这个发现的关键时刻，需要更好的机制 在单细胞水平表征遗传CAD风险基因座，以同时研究遗传和 疾病风险的表观遗传现象。Quertermous实验室先前已经鉴定出TCF 21 GWAS定位于6q23.2位点的CAD相关基因。平滑肌细胞 (SMC)谱系追踪和单细胞RNA测序表明，Tcf 21上调， SMC去分化、增殖和迁移到动脉粥样硬化斑块中。TCF 21表达有助于 SMC表型转变为保护性纤维帽，产生成纤维细胞样细胞，称为 “纤维肌细胞”（FMC）。我们现在正在多个发育时间点研究这种过渡状态， 单细胞转录组学和表观基因组学在动脉粥样硬化ApoE敲除模型中的应用， 与SMC-FMC移行细胞状态相关的染色质可及性变化。而Tcf 21的丢失 在FMC中产生超过50%的减少，仍然存在SMC亚群，可以有助于 FMC和纤维帽。与TCF 21协同促进SMC转化的基因调控网络， 这些网络的下游靶基因仍然未知。核心假设是 这一观点认为TCF 21通过其促进冠心病风险的能力， SMC在血管壁应力环境下的表型转变。为了解决这个假设， 申请人将研究血管疾病背景下Tcf 21过表达的SMC特异性模型， 通过尖端的转录组学和分子生物学技术来表征Tcf 21作用增加的疾病后果， 表观遗传学工具，同时评估单细胞基因转录和染色质可及性， 将scRNAseq与scATACseq组合在血管组织中。目标1将审查增加 Tcf 21在血管平滑肌细胞表型以及动脉粥样硬化斑块细胞组成和解剖结构上的表达 转基因过表达动物。目的2将阐明转录和表观遗传机制， Tcf 21介导SMC去分化和向FMC表型转变，使用单细胞分析 多组RNAseq和ATACseq。这项研究将解决与血管疾病有关的基本问题 病理生理学，包括：i）TCF 21过表达是否增加SMC向FMC的转变，ii）TCF 21过表达是否增加SMC向FMC的转变。 增加SMC向FMC的转化促进更稳定的斑块表型，以及iii）TCF 21如何调节 表观遗传和转录景观，以促进SMC转变为保护性FMC表型。

PROJECT SUMMARY More than 161 genetic loci have been associated with coronary artery disease (CAD) through the genome wide association studies (GWAS) conducted by the CARDIoGRAMplusC4D consortium. However, despite such advances in the understanding of coronary disease, therapeutic targets beyond lipid lowering therapies have yet to reach the clinical stage. At this critical juncture for discovery, there is a need for better mechanistic characterization of the genetic CAD risk loci at the single cell level to simultaneously study the genetic and epigenetic phenomena underlying disease risk. The Quertermous laboratory has previously identified TCF21 as the CAD associated gene mapped by GWAS at the 6q23.2 locus. A combination of smooth muscle cell (SMC) lineage tracing and single cell RNA sequencing has shown that Tcf21 is upregulated and promotes SMC de-differentiation, proliferation and migration into atherosclerotic plaque. TCF21 expression contributes to the phenotypic transition of SMC to the protective fibrous cap, producing fibroblast-like cells termed “fibromyocytes” (FMC). We are now studying this transitional state at multiple developmental time points with single cell transcriptomics and epigenomics in the ApoE knockout model of atherosclerosis and find wide variation in chromatin accessibility associated with the SMC-FMC transitional cell state. While loss of Tcf21 produces more than a 50% decrease in FMC, there remains a subpopulation of SMC that can contribute to FMC and the fibrous cap. The gene regulatory networks that cooperate with TCF21 to promote SMC transition, and the downstream target genes of these networks remain unknown. The central hypothesis underlying this proposal is that TCF21 exerts a protective effect toward CAD risk through its ability to promote phenotypic transition of SMC in the setting of vascular wall stress. To address this hypothesis, the applicant will study a SMC-specific model of Tcf21 over-expression in the setting of vascular disease and characterize the disease consequences of increased Tcf21 action through cutting-edge transcriptomic and epigenetic tools to simultaneously evaluate single cell gene transcription and chromatin accessibility through combined scRNAseq with scATACseq in vascular tissue. Aim 1 will examine the overall effect of increased Tcf21 expression on SMC phenotype as well as atherosclerotic plaque cellular composition and anatomy in transgenic over-expressing animals. Aim 2 will elucidate the transcriptional and epigenetic mechanisms by which Tcf21 mediates SMC de-differentiation and transition to the FMC phenotype using analysis of single cell multi-omic RNAseq and ATACseq. This study will address fundamental questions related to vascular disease pathophysiology, including: i) does TCF21 over-expression increase the SMC to FMC transition, ii) does increased SMC to FMC transition promote a more stable plaque phenotype, and iii) how does TCF21 regulate the epigenetic and transcriptional landscape to promote SMC transition to a protective FMC phenotype.