Genetics of gene expression in human left ventricular myocardium

描述（由申请人提供）： 缺血性心脏病是一种高度遗传性疾病，是全球死亡的主要原因。它每年的总成本为4750亿美元，也是美国最昂贵的疾病。无偏倚的全基因组关联研究（GWAS）已经确定了导致心肌梗死风险的遗传变异。在基于人群的健康队列中，遗传变异已被证明有助于基因表达水平变异，也称为表达数量性状基因座（eQTL），其可能有助于复杂的表型。重要的是，eQTL显示出高度的组织特异性。迄今为止，只有少数人类组织被询问eQTL，没有一个包含人类心脏组织。这项拨款建议建立在我们的试点数据表明，心肌转录显着改变后，暴露于缺血，遗传变异显着决定转录反应。我们将严格测试我们的全球假设，即遗传变异有助于人类左心室心肌的基因表达差异，这些变异有助于临床显著的心肌损伤。目标1：我们将通过在1）100例接受心脏手术的患者中进行全转录组下一代RNA测序来表征急性缺血对左心室心肌转录谱的影响，方法是在CPB的专性缺血性损伤之前和之后对人左心室组织取样; 2）暴露于缺氧和缺血条件下的离体灌注小鼠心脏。目标二：我们将量化常见的遗传变异对缺血的人左心室心肌中基因表达水平的影响，如目的1所述。我们将使用全基因组基因分型和下一代RNA测序技术对缺血损伤前后的心室肌进行独立的eQTL分析。这种方法将提供一个公正的评估基因的贡献，人类心脏基因调控心肌缺血。目标3：为了确定与Aim 2的表达变化相关的遗传变异的临床相关性，我们将在2，400名也接受了CPB心脏手术的患者中检查这些变异。将对eQTL变体进行基因分型，并在该表型非常好的队列中检测其与围手术期心肌损伤、全因死亡率和心室功能障碍的相关性。这些结果将定义链接 基因变异、基因表达改变与人类心肌损伤之间的关系，并显著推进了对心肌损伤的生物学理解。这些见解可能有助于开发新的治疗策略，以减轻人类心肌损伤的负担。

DESCRIPTION (provided by applicant): Ischemic heart disease is a highly heritable disorder and the leading cause of mortality worldwide. At a total cost of $475 billion/year, it is also the most costly disease in the US. Unbiased genome-wide association studies (GWAS) have identified genetic variants contributing to risk of myocardial infarction. In population-based healthy cohorts, genetic variation has been shown to contribute to gene expression level variation, also called expression quantitative trait loci (eQTL), which may contribute to complex phenotypes. Importantly, eQTLs show a high degree of tissue specificity. To date, only a handful of human tissues have been interrogated for eQTLs, with none comprising human cardiac tissue. This grant proposal builds upon our pilot data demonstrating that myocardial transcription is significantly altered upon exposure to ischemia, and that genetic variants markedly determine transcriptional response. We will rigorously test our global hypothesis that genetic variation contributes to differences in gene expression in human left ventricular myocardium, and that these variants contribute to clinically significant myocardial injury. Aim 1: We will characterize the effect of acute ischemia on the transcriptional profile of left ventricular myocardium by performing whole transcriptome next-generation RNA-sequencing in 1) 100 patients undergoing cardiac surgery by sampling human left ventricular tissue prior to, and after the obligate ischemic insult of CPB; 2) isolated perfused mice hearts exposed to hypoxic and ischemic conditions. Aim 2: We will quantify the effects of common genetic variants upon gene expression levels in human left ventricular myocardium subjected to ischemia as described in Aim 1. We will use whole genome genotyping and next generation RNA sequencing to perform independent eQTL analysis in ventricular myocardium before and after ischemic injury. This approach will provide an unbiased assessment of the genetic contribution to human cardiac gene regulation in myocardial ischemia. Aim 3: To determine clinical relevance of genetic variants associated with expression changes from Aim 2, we will examine these variants in a cohort of 2,400 patients who have also undergone cardiac surgery with CPB. eQTL variants will be genotyped and tested for association with perioperative myocardial injury, all-cause mortality and ventricular dysfunction in this very well phenotyped cohort. These results will define the link between genetic variation, altered expression and myocardial injury in humans, and significantly advance the biological understanding of myocardial injury. These insights may facilitate the development of new therapeutic strategies to alleviate the burden of myocardial injury in humans.