Identification and study of the vascular disease gene at 9p21.3

描述(申请人提供)：高达一半的动脉粥样硬化性冠心病(CHD)的风险本质上是遗传的，最近史无前例的大量资源被用于基于协会的研究，使用高密度全基因组扫描来确定与CHD相关的遗传变异。这些研究已经确定，在9号染色体p21.3的基因间隔区，即染色体9p21.3的CHD相关区域(C9CAR)，基因组的一个单一区域与疾病的相关性最高。由该基因变异解释的冠心病归因风险估计为10-15%。除了冠心病，C9CAR的变异还与其他血管疾病有关，包括腹主动脉瘤、中风和外周血管疾病。尽管这个实验室和其他实验室正在进行更多的人类遗传学图谱绘制工作，但他们不太可能识别致病变异，也不太可能阐明与9p21.3变异相关的风险的生物学基础。进一步的进展将需要在基本的分子生物学和动物模型方法方面做出努力。虽然在这个9p21.3区域有几个基因，但没有一个基因与疾病相关的变异明显相关，导致变异的原因也没有定义。最近令人信服的证据表明，CDKN2B基因和CDKN2B基因座上名为ANRIL的非编码反义RNA是最有可能与9p21.3变异相关的候选基因。这里提出的研究将确定这两个候选基因中的哪个是相关基因，9p21.3变异改变该基因功能的机制，以及它反过来调节的与疾病相关的基本途径。特定目的1的实验将研究CDKN2B和ANRIL等位基因之间的等位基因表达失衡，并将这种失衡与这些基因以及基因间的C9CAR区域的变异联系起来。这些研究将确定致病基因并定位顺式作用的转录调控序列。在这一目标中的其他实验将表征C9CAR上可能的增强子元件，识别与这些元件结合的转录因子，并提供对细胞类型和信号通路的见解，这些细胞类型和信号通路介导与该区域相关的风险。特定目的2将在apoE缺失的动脉粥样硬化小鼠模型中使用9p21.3处的CDKN2B和其他基因的定向缺失，以提供对疾病风险的细胞和分子方面的见解。最后，在特定的目标3中，有针对性的体外研究将进一步研究CDKN2B或ANRIL如何调节血管细胞类型的基本细胞命运决定，并促进动脉粥样硬化性疾病。这项工作将确定9p21.3的致病基因，以及与疾病相关的上下游通路，为进一步研究和治疗提供靶向。 与公共卫生相关：世界各地的科学家团队付出了巨大的费用和努力，从而确定了与各种形式心血管疾病的遗传风险相关的人类基因组区域。还需要更多的研究来了解涉及的特定基因，以及它们如何在疾病过程中发挥作用。这些信息将有助于开发更好的治疗这些疾病的方法。

DESCRIPTION (provided by applicant): As much as half of the risk for atherosclerotic coronary heart disease (CHD) is genetic in nature, and an unprecedented amount of resources have recently been directed at association-based studies employing high density genome-wide scanning to identify genetic variation associated with CHD. These studies have identified a single region of the genome as the most highly associated with disease in an intergenic segment of chromosome 9 at p21.3, the Chromosome 9p21.3 CHD-Associated Region (C9CAR). The attributable risk for CHD explained by variation in this locus has been estimated at 10-15%. In addition to CHD, variants at C9CAR have been associated with other vascular diseases, including abdominal aortic aneurysm, stroke, and peripheral vascular disease. Although additional human genetics mapping efforts are underway in this laboratory and others, it is unlikely that they will identify the causative variation or elucidate the biology underlying the risk associated with 9p21.3 variants. Further progress will require efforts with basic molecular biology and animal model approaches. While there are several genes in this region of 9p21.3, none have been clearly linked to the disease-associated variation, and the causative variation has not been defined. Compelling recent evidence now suggests that a cyclin-dependent kinase inhibitor gene, CDKN2B, and a non-coding antisense RNA in the CDKN2B locus named ANRIL, are the most likely candidate genes linked to the variation at 9p21.3. Studies proposed here will identify which of these two candidates is the related gene, the mechanism by which 9p21.3 variation alters the function of this gene, and the fundamental disease-related pathways that it in turn regulates. Experiments in Specific Aim 1 will investigate allelic expression imbalance between the alleles of CDKN2B and ANRIL, and link this imbalance to variation in these genes as well as the intergenic C9CAR region. These studies will identify the causative gene and localize cis-acting transcriptional regulatory sequences. Additional experiments in this aim will characterize putative enhancer elements at C9CAR, identify the transcription factors that bind these elements and provide insights into cell types and signaling pathways that mediate the risk associated with this region. Specific Aim 2 will employ targeted deletion of CDKN2B and other genes at 9p21.3 in the apoE null atherosclerosis mouse model to provide insights into the cellular and molecular aspects of disease risk. Finally, in Specific Aim 3, targeted in vitro studies will further investigate how CDKN2B or ANRIL regulate basic cell fate decisions in vascular cell types and contribute to atherosclerotic disease. This work will identify the causative gene at 9p21.3, and disease related upstream and downstream pathways for further study and therapeutic targeting. PUBLIC HEALTH RELEVANCE: Significant expense and effort by groups of scientists around the world has led to identification of regions of the human genome that are associated with the genetic risk for various forms of cardiovascular disease. Additional research is required to understand the specific genes involved, and how they work to contribute to the disease process. Such information will allow the development of better therapeutics for these diseases.