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可遗传的疾病，是世界范围内死亡的主要原因。每年的总成本为4750亿美元，它也是美国成本最高的疾病。无偏全基因组关联研究(GWARs)已经确定了导致心肌梗死风险的基因变异。在以人群为基础的健康队列中，遗传变异被证明是导致基因表达水平变异的原因，也被称为表达数量性状基因座(EQTL)，这可能导致复杂的表型。重要的是，eQTL表现出高度的组织特异性。到目前为止，只有少数几个人类组织被询问eQTL，没有一个组织包括人类心脏组织。这项拨款建议建立在我们的试点数据基础上，该数据表明，心肌转录在暴露于缺血时显著改变，并且基因变异显著决定转录反应。我们将严格检验我们的全球假设，即遗传变异导致人类左室心肌基因表达的差异，以及这些变异导致临床上显著的心肌损伤。目的：通过对100例心脏手术患者进行下一代全转录组RNA测序，研究急性缺血对左室心肌转录水平的影响：1)100例心脏手术患者在体外循环(CPB)前、后取左室心肌组织标本；2)体外循环(CPB)条件下体外循环(CPB)对小鼠离体心脏的灌流。目的2：我们将像目标1中描述的那样，量化常见的基因变异对缺血后人左室心肌基因表达水平的影响。我们将使用全基因组基因分型和下一代RNA测序对缺血损伤前后的左室心肌进行独立的eQTL分析。这一方法将为心肌缺血时基因对人类心脏基因调控的贡献提供一个公正的评估。目的3：为了确定与目标2的表达变化相关的基因变异的临床相关性，我们将在2400名同样接受体外循环心脏手术的患者中检查这些变异。在这个表型良好的队列中，将对eQTL变异进行基因分型，并测试其与围手术期心肌损伤、全因死亡率和心功能不全的相关性。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，并极大地促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.