The molecular mechanisms underlying arrhythmogenic right ventricular dysplasia/ca

描述（由申请人提供）：致心律失常性右心室发育不良/心肌病（ARVD/C）是心肌病的一种遗传形式，其典型特征为右心室功能障碍，最近也出现左心室功能障碍、心室纤维化/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（MLC 2 v）-Cre小鼠通过桥粒组分桥粒斑蛋白（desmo cKO）的条件性心脏特异性消融产生了ARVD/C小鼠模型。由于MLC 2 v-Cre在一系列心肌细胞谱系中表达，因此我们建议鉴定有助于在我们的模型中观察到的不同表型方面的肌细胞群体的子集。我们的模型对连接蛋白信号传导表现出独特的影响，连接蛋白信号传导被认为在肌细胞-肌细胞和肌细胞-成纤维细胞粘附中起关键作用。因此，我们也建议确定连接蛋白信号转导缺陷如何导致肌细胞-肌细胞和肌细胞-成纤维细胞粘附的变化，并有助于ARVD/C的表型方面。我们的模型还表现出心脏细胞溶质2-连环蛋白积累，这是已知导致异常2-连环蛋白核转位/信号传导的效应。因此，我们建议使用基因治疗方法通过抑制2-连环蛋白的作用和信号传导来挽救我们的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。这项为期五年的提案的目标是了解ARVD/C各种临床特征的细胞机制，并测试当前和新药治疗的效果以及抑制2-catenin对我们的ARVD/C模型预后的作用。这些结果使我们假设桥粒斑蛋白在心肌细胞谱系的亚群中起重要作用，并且桥粒斑蛋白缺陷引起（i）连接蛋白信号传导缺陷，其影响肌细胞-肌细胞和肌细胞-成纤维细胞粘附以及细胞粘附/连接组分的错误定位/丧失，其影响肌细胞命运并导致ARVD/C。具体目标包括：（1）通过消融不同心肌细胞谱系中的桥粒斑蛋白来确定导致ARVD/C的心肌细胞亚群。(2)确定连接蛋白信号传导如何影响我们模型中的肌细胞-肌细胞和肌细胞-成纤维细胞粘附。(3)通过抑制（a）2-连环蛋白以及（B）K+离子通道和2-肾上腺素能受体的作用，挽救或改变我们模型中ARVD/C的进展。公共卫生相关性：这项为期五年的提案的目标是（i）了解致命性人类疾病，致瘤性右心室发育不良/心肌病（ARVD/C）的各种临床特征的细胞机制，以及（ii）研究操纵分子靶点和给予ARVD/C的当前和新型药物治疗对试验小鼠模型预后的影响，我们培育出了携带人类ARVD/C的基因。这些研究将确定对ARVD/C进展至关重要的分子途径，从而提高我们对这种疾病的总体理解，并确定治疗这种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.