Identification of genetic modifiers of heart disease

描述(申请人提供)：心力衰竭是世界范围内死亡的一个重要原因，有许多心脏病因，包括心肌病引起的收缩功能障碍。然而，由于人群中未发现的遗传差异，心肌病的预后在患者中具有很高的变异性。几乎所有的方法都很难确定导致这些可变结果的遗传风险因素，除了分析因明显的生物学合理性而选择的候选基因。我们的项目将在小鼠身上使用一种无偏见的基因作图方法来识别调节心肌病进展和结果的新基因。在一种经过充分研究的扩张型心肌病小鼠模型中(Calequestrin转基因小鼠)，我们发现在疾病进展和生存方面存在显著的菌株特异性差异。使用多个杂交的QTL定位方法，我们已经确定了七个不同的遗传位点，Hrtfm1-7(心力衰竭修饰物)，它们改变了疾病的进展。这些基因座目前正被分离在同源基因系中。目的1：我们将在两种不同的心肌病背景下对分离的修饰基因进行表型验证；(1)使用原始的CSQ转基因作为遗传敏感剂；(2)使用由主动脉收缩引起的压力超负荷的外科敏感剂。在两个模型中都显示出稳健效应的独立基因座将优先用于进一步研究。目标2：我们将使用多种方法精细定位这些基因座中最稳健的一个。我们将为每个座位生成一系列嵌套的同源基因系，并在遗传和手术敏感剂的背景下分析它们的表型效应。同时，我们将继续生成与新的近交系的图谱数据，以利用祖先的单倍型共享模式来描绘基因座。我们还将识别在心脏表达上显示特定菌株差异的基因。目的3：我们将使用小鼠转基因和基因敲除方法来研究Hrtfm2基因座的一个引人注目的候选基因。随着其他基因座的其他强候选基因被确定，最引人注目的基因将经历同样的功能丧失和功能获得的验证。我们项目的长期目标是在小鼠中识别候选的心力衰竭调节基因，以便在人类心肌病人群中进行评估。对这些基因修饰物的鉴定和鉴定将增加我们对心肌病和心力衰竭发生和发展的分子机制的了解。

DESCRIPTION (provided by applicant): Heart failure is a significant cause of death worldwide with a number of cardiac etiologies including systolic dysfunction due to cardiomyopathy. However, the prognosis of cardiomyopathy is highly variable among patients, due to undiscovered genetic differences in the population. Identification of genetic risk factors that contribute to these variable outcomes has been refractory to nearly all approaches except for the analysis of candidate genes chosen for obvious biological plausibility. Our project will use an unbiased genetic mapping approach in the mouse to identify novel genes that modulate the progression and outcome of cardiomyopathy. In a well-studied mouse model of dilated cardiomyopathy (the Calsequestrin transgenic mouse), we discovered dramatic strain-specific differences in both disease progression and survival. Using a QTL mapping approach in multiple crosses, we have identified seven distinct genetic loci, Hrtfm1-7 (Heart failure modifier), that alter the disease progression. These loci are currently being isolated in congenic lines. Aim 1: We will phenotypically validate the isolated modifier loci in two distinct cardiomyopathic disease contexts; (1) with the original CSQ transgene as a genetic sensitizer and (2) with a surgical sensitizer using pressure overload induced by aortic constriction. The isolated loci that show robust effects in both models will receive priority for further investigation. Aim 2: We will fine-map the most robust of these loci using multiple approaches. We will generate a series of nested congenic lines for each locus and analyze their phenotypic effects in the context of both the genetic and surgical sensitizers. In parallel, we will continue to generate mapping data with new inbred strains to take advantage of ancestral haplotype sharing patterns to delineate the loci. We will also identify genes that show strain-specific differences in heart expression. Aim 3: We will investigate a compelling candidate gene for the Hrtfm2 locus using mouse transgenic and knockout approaches. As other strong candidate genes are identified for the other loci, the most compelling will undergo this same loss-of-function and gain-of-function validation. Our project's long-term goal is to identify candidate heart-failure modifier genes in the mouse for evaluation in the human cardiomyopathy population. Identification and characterization of these genetic modifiers will increase our understanding of the molecular mechanisms underlying the development and progression of cardiomyopathy and heart failure.