Mechanism of the coronary heart disease association at chromosome 6q23.2

描述（由申请人提供）： 动脉粥样硬化性冠心病（CHD）的大部分风险本质上是遗传的，最近已采用基于全基因组关联的研究来确定CHD相关的变异。通过对22，233例病例和64，762例对照的全基因组数据进行大规模冠状动脉疾病全基因组复制和Meta分析（CARDIoT）研究，鉴定出一个新的基因座，位于染色体6的q23.2，在编码碱性螺旋-环-螺旋（bHLH）转录因子TCF 21的基因座内。在心脏病研究中，6个最高度相关的SNP是形成疾病相关单倍型的基因内和上游的相关eQTL变体。预测这些变体中的一些破坏可能调节TCF 21表达的转录因子或miRNA结合位点。众所周知，bHLH转录因子调节细胞命运决定，这对胚胎发育和疾病相关途径至关重要。TCF 21首先在这个实验室和另外两个实验室被克隆，并显示出标记引起冠状动脉循环的祖细胞。靶向缺失Tcf 21与破坏血管平滑肌细胞（SMC）的发展有关，体外研究表明TCF 21是SMC中转录和细胞命运决定的重要调节因子。在这个位点的简单LD结构，和已知的身份的冠心病相关基因的病因，建议分子，细胞和动物模型实验方法，以确定上游和下游信号通路，以阐明该位点的变化有助于冠心病的风险的机制。本文提出的研究将确定6q23.2变异改变TCF 21表达和功能的机制，以及SMC在这方面失调以促进CHD的血管细胞通路。具体目标1中的实验将研究疾病相关或相关变异是否调节TCF 21表达。这些研究将表征DNA结合转录因子和mRNA结合miRNA和调节蛋白，为介导与该区域相关风险的上游信号通路提供见解。在特定目标2中，下游TCF 21遗传程序将通过采用组合ChIP-Seq和基因表达方法鉴定血管SMC中受该转录因子调控的体内结合序列和相关基因来表征。Specific Aim 3将在小鼠血管动脉粥样硬化和重塑模型中采用Tcf 21的靶向缺失，以提供对疾病风险的细胞和分子方面的机制见解，Specific Aim 4将进一步研究这些分子途径与体外细胞模型。总之，这些研究有望提供TCF 21基因座变异改变SMC基本功能和易患血管疾病的机制的全面图景。

DESCRIPTION (provided by applicant): Much of the risk for atherosclerotic coronary heart disease (CHD) is genetic in nature, and genome wide association based studies have recently been employed to identify CHD-related variation. One of the novel loci identified through the large-scale Coronary ARtery DIsease Genome wide Replication and Meta- analysis (CARDIoGRAM) study of whole genome data for 22,233 cases and 64,762 controls is located on chromosome 6 at q23.2, within the locus encoding the basic helix-loop-helix (bHLH) transcription factor TCF21. Six of the most highly associated SNPs in the CARDIoGRAM study are correlated eQTL variants within and upstream of the gene that form a disease-associated haplotype. Some of these variants are predicted to disrupt transcription factor or miRNA binding sites that likely regulate TCF21 expression. The bHLH transcription factors are well known to regulate cell fate decisions that are critical for embryonic developmental and disease-related pathways. TCF21 was first cloned in this and two other laboratories and shown to mark progenitor cells that give rise to the coronary circulation. Targeted deletion of Tcf21 has been associated with disrupted vascular smooth muscle cell (SMC) development, and in vitro studies have implicated TCF21 as an important regulator of transcription and cell fate decisions in SMC. The simple LD structure in this locus, and the known identity of the causal CHD-associated gene, suggest molecular, cellular, and animal model experimental approaches to identifying upstream and downstream signaling pathways to elucidate the mechanisms by which variation in this locus contributes to CHD risk. Studies proposed here will identify the mechanisms by which variation at 6q23.2 alters TCF21 expression and function, and the vascular cell pathways that are dysregulated in SMC in this regard to promote CHD. Experiments in Specific Aim 1 will investigate whether disease-associated or correlated variation regulates TCF21 expression. These studies will characterize DNA-binding transcription factors and mRNA-binding miRNA and regulatory proteins, providing insights into upstream signaling pathways that mediate the risk associated with this region. In Specific Aim 2, the downstream TCF21 genetic program will be characterized by identifying the in vivo binding sequences and related genes that are regulated by this transcription factor in vascular SMC, employing combined ChIP-Seq and gene expression approaches. Specific Aim 3 will employ targeted deletion of Tcf21 in murine vascular atherosclerosis and remodeling models to provide mechanistic insights into the cellular and molecular aspects of disease risk, and Specific Aim 4 will further investigate these molecular pathways with in vitro cellular models. Together, these studies are expected to provide a comprehensive picture of the mechanisms by which variation in the TCF21 locus alters basic SMC function and predisposes to vascular disease.