The role of Raf-MEK signaling in the pathogenesis of hypertrophic cardiomyopathy

描述（由申请人提供）：肥厚性心肌病（HCM）是一种以心室心肌异常增厚为特征的疾病，是心力衰竭和猝死的常见遗传原因。这种情况的患病率是1:500，在过去的二十年里，在理解孟德尔疾病的遗传基础方面取得了巨大的进步。然而，尽管对这种疾病有丰富的遗传知识，但新的治疗方法的发展仍然有限。与HCM相关的基因编码心肌细胞肉瘤蛋白，并且已经创建了一些啮齿类动物模型来模拟疾病过程的组成部分。然而，使用哺乳动物模型进行大规模筛选新疗法的成本和时间令人望而却步。最近，斑马鱼幼虫作为疾病建模和表型驱动小分子筛选的工具的出现，为哺乳动物模型系统提供了一个可行的替代方案。我们最近建立了一种人类肥厚性心肌病心肌肌钙蛋白t突变的斑马鱼模型。将我们的斑马鱼模型和HCM小鼠模型进行比较，发现心脏利钠肽基因nppa和nppb在两种HCM模型中都被强烈诱导。利用这一发现，我们创建了一个斑马鱼转基因报告系来模拟nppb基因的病理激活。然后，我们进行了靶向激酶抑制剂筛选，以确定继发于肥厚刺激的nppb病理诱导的重要途径。我们发现丝裂原活化蛋白激酶（MEK1/2）在该信号通路的病理诱导中起重要作用。本应用的重点是研究Raf/MEK信号级联在肉瘤基因突变的病理生理中的作用。目的1。确定Raf-MEK信号级联的哪些成分在HCM病理生理中是重要的。利用肌体基因突变的斑马鱼模型，我们将测试Raf-MEK信号级联的哪些成分在体内激活肥厚信号通路中是重要的。我们将结合小分子抑制剂和基因敲除技术来靶向这些途径。目标2。描述在HCM哺乳动物模型中选择性抑制MEK信号传导的作用。我们将在肥厚性心肌病的哺乳动物模型中确定是否药物抑制MEK信号可以预防疾病的发展。首先，我们将确定当肉瘤基因突变启动肥厚信号级联时的发育时间，以便我们可以定义肥厚前和肥厚间期。然后，我们将使用一种小分子抑制剂选择性地靶向MEK1/2，以确定靶向该激酶是否可以在不引起心脏毒性的情况下阻止HCM的发展。由肉瘤基因突变引起的肥厚性心肌病是一种常见的遗传性心血管疾病，目前尚无有效的预防方法。我们将利用新的体内模型来确定操纵Raf-MEK信号通路是否是一种有效的方法来预防由肉瘤基因突变引起的心室肥厚的发展。

DESCRIPTION (provided by applicant): Hypertrophic cardiomyopathy (HCM), a disease characterized by abnormal thickening of the ventricular myocardium, is a common genetic cause of heart failure and sudden death. The prevalence of this condition is 1:500, and over the last twenty years there has been tremendous advancement in understanding the genetic underpinnings of this Mendelian disorder. However, despite the robust genetic knowledge that exists for this disease, the development of novel treatments has been limited. The genes implicated in HCM encode for cardiomyocyte sarcomeric proteins, and select rodent models have been created that model components of the disease process. However, performing a large scale screen for novel therapeutics using mammalian animal models is cost and time prohibitive. Recently, the emergence of the larval zebrafish as a tool for disease modeling and phenotype-driven small molecule screens has provided a viable alternative to mammalian model systems. We recently developed a zebrafish model of a human hypertrophic cardiomyopathy mutation in cardiac Troponin T. A comparison between our zebrafish model and a mouse model of HCM, discovered that the cardiac natriuretic peptide genes, nppa and nppb, were robustly induced in both HCM models. Utilizing this discovery, we created a zebrafish transgenic reporter line that models the pathologic activation of the nppb gene. We then performed a targeted kinase inhibitor screen to identify pathways important in the pathological induction of nppb secondary to hypertrophic stimuli. We discovered that mitogen-activated protein kinase kinase (MEK1/2) was important in the pathological induction of this signaling pathway. This application is focused on investigating the role of the Raf/MEK signaling cascade in the pathophysiology of sarcomeric gene mutations. Aim 1. Determine which components of the Raf-MEK signaling cascade are important in HCM pathophysiology. Utilizing a zebrafish model of a sarcomeric gene mutation, we will test which components of the Raf-MEK signaling cascade are important in activating hypertrophic signaling pathways in vivo. We will target these pathways using a combination of small molecule inhibitors, and genetic knock down techniques. Aim 2. Delineate the effect of selective inhibition of MEK signaling in a mammalian model of HCM. We will determine if pharmacological inhibition of MEK signaling can prevent the development of disease in a mammalian model of hypertrophic cardiomyopathy. Frist, we will determine the developmental timing of when sarcomeric gene mutations initiate the hypertrophic signaling cascade so that we can define a prehypertrophic and hypertrophic interval. We will then selectively target MEK1/2 using a small molecule inhibitor to determine if targeting this kinase can prevent the development of HCM without causing cardiotoxicity. Hypertrophic cardiomyopathy caused by sarcomeric gene mutations is a common inherited cardiovascular condition with no effective methods to prevent the development of disease. We will utilize novel in vivo models to determine if manipulation of the Raf-MEK signaling pathway is an effective method to prevent the development of ventricular hypertrophy caused by sarcomeric gene mutations.