The molecular mechanisms underlying arrhythmogenic right ventricular dysplasia/ca

描述(申请人提供)：致心律失常性右室发育不良/心肌病(ARVD/C)是一种遗传性心肌病，其典型特征是右心功能不全，但最近也有左心功能不全，室纤维/脂肪替代和室性心律失常导致心源性猝死。我们使用肌球蛋白轻链-2v(MLC2v)-Cre小鼠，通过有条件地去除桥粒成分桥粒蛋白(DesmoCKO)，建立了ARVD/C的小鼠模型。由于MLC2v-Cre在一系列心肌细胞系中表达，我们建议确定在我们的模型中观察到的不同表型方面的心肌细胞亚群。我们的模型显示了对连接蛋白信号的独特影响，连接蛋白信号被认为在肌细胞-肌细胞和肌细胞-成纤维细胞的黏附中发挥关键作用。因此，我们还建议确定连接蛋白信号的缺陷如何导致肌细胞-肌细胞和肌细胞-成纤维细胞黏附的改变，并有助于ARVD/C的表型。我们的模型还显示了心肌细胞内2-连环蛋白的积聚，这是一种已知导致2-连环蛋白核转位/信号异常的效应。因此，我们建议通过抑制2-连环蛋白的作用和使用基因治疗方法发出信号来挽救我们的ARVD/C模型。我们还建议在我们的ARVD/C模型中评估抑制钾离子通道和2-肾上腺素能受体作用的效果。这个为期五年的计划的目标是了解ARVD/C各种临床特征背后的细胞机制，并测试现有和新药治疗的效果，以及抑制2-catenin对我们的ARVD/C模型预后的影响。这些结果使我们提出以下假设：桥粒蛋白在心肌细胞亚群中起重要作用，桥粒蛋白缺陷导致(1)连接蛋白信号缺陷，影响心肌细胞-肌细胞和肌细胞-成纤维细胞的黏附和细胞黏附/连接成分的错误定位/丢失，从而影响心肌细胞的命运并导致ARVD/C。具体目的包括：(1)通过在不同的心肌细胞谱系中去除桥粒蛋白，确定与ARVD/C有关的心肌细胞亚群。(2)在我们的模型中，确定连接蛋白信号如何影响肌细胞-肌细胞和肌细胞-成纤维细胞的黏附。(3)通过抑制(A)2-连环蛋白、(B)K+离子通道和2-肾上腺素能受体的作用，挽救或改变ARVD/C的进展。与公共卫生相关：这项五年计划的目标是(I)了解导致心律失常性右室发育不良/心肌病(ARVD/C)的各种人类致命疾病临床特征潜在的细胞学机制，以及(Ii)研究针对ARVD/C的分子靶点的操纵以及目前和新药治疗对我们培育的携带人类疾病ARVD/C的测试鼠模型的预后的影响。这些研究将确定对于ARVD/C的进展至关重要的分子途径，从而提高我们对该疾病的总体认识，以及确定治疗这一致命疾病的治疗靶点。

DESCRIPTION (provided by applicant): Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a genetic form of cardiomyopathy, which is typically characterized by right but also recently left ventricular dysfunction, fibrotic/fatty replacement of the ventricle and ventricular arrhythmias leading to sudden cardiac death. We have generated a mouse model of ARVD/C through conditional cardiac-specific ablation of the desmosomal component, desmoplakin, (desmo cKO) using the myosin-light chain-2v (MLC2v)-Cre mouse. Since MLC2v-Cre is expressed in a range of cardiomyocyte lineages, we propose to identify the subsets of myocyte populations contributing to the distinct phenotypic aspects observed in our model. Our model exhibits unique effects on connexin signaling, which are thought to play a key role in myocyte-myocyte and myocyte-fibroblast adhesion. Thus, we also propose to determine how defects in connexin signaling lead to changes in myocyte-myocyte and myocyte- fibroblast adhesion and contribute to phenotypic aspects of ARVD/C. Our model also exhibits cardiac cytosolic 2-catenin accumulation, which is an effect known to lead to aberrant 2-catenin nuclear translocation/ signaling. Thus, we propose to rescue our ARVD/C model by inhibiting 2-catenin's actions and signaling using a gene therapy approach. We also propose to assess the effects of inhibiting potassium ion channel and 2-adrenergic receptor actions in our ARVD/C model. The goal of this five-year proposal is to understand the cellular mechanisms underlying the various clinical features of ARVD/C as well as test the effects of current and new drug treatments as well as inhibiting 2-catenin's actions on the prognosis of our ARVD/C model. These results have led us to the hypotheses that desmoplakin plays an essential role in subsets of cardiomyocyte lineages and desmoplakin defects cause (i) connexin signaling defects which affect myocyte-myocyte and myocyte- fibroblast adhesion and mislocalization/loss of cell adhesion/junctional components, which affect myocyte cell fate and result in ARVD/C. Specific Aims include: (1) To determine the subset of cardiomyocytes responsible for ARVD/C, by ablating desmoplakin in distinct cardiomyocyte lineages. (2) To determine how connexin signaling affects myocyte-myocyte and myocyte-fibroblast adhesion in our model. (3) To rescue or alter the progression of ARVD/C in our model by inhibiting the actions of (a) 2-catenin's as well as the (b) K+ ion channel and 2-adrenergic receptor. PUBLIC HEALTH RELEVANCE: The goal of this five-year proposal is to (i) understand the cellular mechanisms underlying the various clinical features of the fatal human disease, arrhythmogenic right ventricular dysplasia/ cardiomyopathy (ARVD/C) and (ii) study the impact of manipulating molecular targets and administering current and new drug treatments for ARVD/C on the prognosis of a test mouse model, which we have generated to genetically carry the human disease ARVD/C. These studies will identify molecular pathways that are essential for the progression of ARVD/C and thereby improve our general understanding of this disease, as well as identify therapeutic targets for treating this fatal disease.