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

描述（由申请人提供）：肥厚型心肌病（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。这种疾病的患病率是1：500，在过去的20年里，人们对这种孟德尔疾病的遗传基础的理解有了巨大的进步。然而，尽管对这种疾病存在强大的遗传知识，但新治疗方法的发展受到限制。与HCM有关的基因编码心肌细胞肌节蛋白，并且已经创建了选择的啮齿动物模型，该模型是疾病过程的模型组成部分。然而，使用哺乳动物动物模型进行大规模筛选新的治疗剂是成本和时间过高的。最近，出现的幼虫斑马鱼作为疾病建模和表型驱动的小分子筛选的工具，提供了一个可行的替代哺乳动物模型系统。我们最近开发了一种人类肥厚型心肌病心肌肌钙蛋白T突变的斑马鱼模型。我们的斑马鱼模型和HCM小鼠模型之间的比较发现，心脏利钠肽基因，nppa和nppb，在两种HCM模型中均被强烈诱导。利用这一发现，我们创建了一个斑马鱼转基因报告线模型的nppb基因的病理激活。然后，我们进行了靶向激酶抑制剂筛选，以确定在继发于肥大刺激的nppb病理诱导中重要的途径。我们发现，丝裂原活化蛋白激酶激酶（MEK 1/2）是重要的病理诱导这一信号通路。本申请的重点是研究Raf/MEK信号级联在肌节基因突变的病理生理学中的作用。目标1。确定Raf-MEK信号级联的哪些组分在HCM病理生理学中是重要的。利用斑马鱼模型的肌节基因突变，我们将测试哪些组件的Raf-MEK信号级联是重要的，在体内激活肥大信号通路。我们将使用小分子抑制剂和基因敲除技术的组合来靶向这些途径。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。我们将确定药物抑制MEK信号传导是否可以预防肥大性心肌病哺乳动物模型中疾病的发展。首先，我们将确定肌节基因突变启动肥大信号级联的发育时间，以便我们可以定义肥大前和肥大间隔。然后，我们将使用小分子抑制剂选择性地靶向MEK 1/2，以确定靶向这种激酶是否可以防止HCM的发展而不引起心脏毒性。肌节基因突变引起的肥厚型心肌病是一种常见的遗传性心血管疾病，目前尚无有效的方法来预防疾病的发展。我们将利用新的体内模型，以确定是否Raf-MEK信号通路的操作是一种有效的方法，以防止由肌节基因突变引起的心室肥大的发展。

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.