Canonical Wnt Signaling in Pathogenesis and Rescue of ARVC Phenotype

描述其表型发病机理的机会。基于结构和功能的相似性 斑珠蛋白（PG），一种桥粒蛋白和一个成员犰狳家族，和<$-连环蛋白，信号 作为经典Wnt信号传导的转导子，也是一种犰狳蛋白，我们研究了竞争性相互作用 PG（又名<$-连环蛋白）和<$-连环蛋白之间的相互作用抑制了经典的Wnt信号传导，导致肌细胞 细胞凋亡和增强的脂肪形成。为了验证这一假设，我们在心肌组织中制备了限制性桥斑蛋白， (DP)缺陷小鼠和siRNA介导的DP缺陷心房肌细胞。我们发现DP缺乏导致 PG的核转位，经典Wnt信号的抑制，心肌细胞凋亡，纤维化和 脂肪生成 我们建议确定心脏中多余脂肪细胞的细胞来源，描绘其分子生物学特征。 抑制经典Wnt信号传导的基础，并通过激活经典Wnt信号传导来防止表型 发信号。目标是：1.通过体内遗传学方法鉴定ARVC中过量脂肪细胞的细胞来源， 命运映射和共培养研究; 2.为了确定抑制的经典Wnt信号传导是否是一个重要的信号传导机制， 通过可滴定水平的突变桥粒表达的ARVC发病的共同机制 转基因小鼠心脏中的蛋白质; 3.为了阐明核PG抑制细胞增殖的机制， 通过研究蛋白质-蛋白质相互作用和PG对Wnt信号转导的有效组装的影响， Wnt核心蛋白复合物; 4.通过激活典型的ARVC表型来在体内和体内拯救ARVC表型 Wnt信号通过条件性激活抗降解的连环蛋白和药理学激活 因此，满足科赫因果关系假设。转基因小鼠研究，转导心脏 肌细胞和肌成纤维细胞被设计成描绘每个目标的组成部分。结果可能 阐明桥粒ARVC的分子发病机制， 用于治疗和预防人类ARVC的诊断标志物和新的药理学靶点。 项目描述第6页

the opportunity to delineate the pathogenesis of its phenotype. Based on structural and functional similarities between plakoglobin (PG), a desmosomal protein and a member armadillo family, and ¿-catenin, the signal transducer of the canonical Wnt signaling and also an armadillo protein, we posit competitive interactions between PG (aka ¿-catenin) and ¿-catenin suppresses the canonical Wnt signaling, leads to myocyte apoptosis and enhanced adipogenesis. To test the hypothesis, we generated cardiac-restricted desmoplakin (DP) deficient mice and siRNA-mediated DP-deficient atrial myocytes. We showed DP-deficiency led to nuclear translocation of PG, suppression of the canonical Wnt signaling, myocyte apoptosis, fibrosis and adipogenesis. We propose to identify the cellular origin of excess adipocytes in the heart, delineate the molecular basis of suppressed canonical Wnt signaling and prevent the phenotype by activating the canonical Wnt signaling. The aims are: 1. To identify the cellular origin of excess adipocytes in ARVC through in vivo genetic fate-mapping and co-culture studies; 2. To determine whether suppressed canonical Wnt signaling is a common mechanism for the pathogenesis of ARVC by expression of titratable levels of mutant desmosomal proteins in transgenic mice hearts; 3. To delineate the mechanism by which nuclear PG suppresses the canonical Wnt signaling by studying protein-protein interactions and the effects of PG on effective assembly of Wnt core proteins complex; 4. To rescue the ARVC phenotype in vivo and in vivo by activating the canonical Wnt signaling through conditional activation of degradation-resistant ¿-catenin and pharmacological activation and hence, to fulfill the Koch's postulates of causality. Studies in genetically modified mice, transduced cardiac myocytes and myofibroblasts are designed to delineate the components of each aim. The results could elucidate the molecular pathogenesis of desmosomal ARVC and lead to identification of new molecular diagnostic markers and novel pharmacological targets for the treatment and prevention of ARVC in humans. Project Description Page 6