Non-junctional roles of desmosome proteins in the pathogenesis of arrhythmogenic cardiomyopathy

项目总结 心血管疾病仍然是美国的主要死亡原因。重新编程的最新进展 从心脏病患者的体细胞转化为诱导多能干细胞(IPSCs)使体外建模 用于病原学研究和治疗筛选的人类心脏病。传统上，弱化的桥粒 交界处被认为是致心律失常的心肌病(AC)的主要致病机制，引起 通过五种桥粒成分蛋白的突变。AC的病理特征是进行性纤维脂肪 心肌细胞(CMS)的替代主要是RV中CM细胞凋亡的增加，导致突然 年轻时的死亡。我们已经建立了一种新的方法来诱导成体样的、以脂肪酸氧化为主的 起源于iPSCs的原始CMS(IPSC-CMS)的代谢，并建立了第一个代谢成熟- 基于体外心脏病模型，以阐明人类AC的新病原学见解(《自然》，2013)。 我们发现，在ACCMS中，在正常的PPARγ介导的代谢成熟后，PPARα异常激活 导致CMS过度脂肪生成、细胞凋亡、钠通道缺陷和钙处理缺陷 桥粒突变，概括了AC心脏的病理特征。使用我们的交流模型和 来自病理性人AC心脏的样本，我们在这里表明，白蛋白是胰岛素-P85的关键成分 代谢信号复合体。桥粒突变导致蛋白降解速度加快，PI3K/Akt降低 激活和过度激活GSK3β，下调microRNA(MiR)簇，导致后续 PPARγ异常激活和CM细胞凋亡。重要的是，我们使用了遗传和细胞方法来证实 我们的致病途径在人类AC心脏和AC小鼠模型中的临床相关性。我们 建议在此进一步阐明由B型流感病毒引起的失调和非连接的信号网络 白蛋白缺乏，研究白化亲和素-2缺乏如何解除对额外信号通路的调节，并发现 使用体外IPSC-CM模型和小鼠模型治疗AC的临床安全治疗药物 交流电。

PROJECT SUMMARY Cardiovascular diseases remain the major cause of death in the US. Recent advances in reprogramming somatic cells from cardiac patients into induced pluripotent stem cells (iPSCs) enables in vitro modeling of human cardiac diseases for pathogenic studies and therapeutic screens. Traditionally, weakened desmosome junctions are considered the main pathogenic mechanism for Arrhythmogenic Cardiomyopathy (AC), caused by mutations in five desmosome component proteins. Pathological hallmarks of AC are progressive fibro-fatty replacement of cardiomyocytes (CMs) with increased CM apoptosis primarily in the RV, leading to sudden death in the young. We have established a novel method to induce adult-like, fatty acid oxidation-dominant metabolism of primitive CMs derived from iPSCs (iPSC-CMs) and established the first metabolic maturation- based in vitro cardiac disease model for elucidation of novel pathogenic insights for human AC (Nature, 2013). We showed that abnormal PPARγ activation after normal PPARα-mediated metabolic maturation in AC CMs resulted in exaggerated lipogenesis, apoptosis, sodium channel deficits and defective Ca2+ handling in CMs with desmosome mutations, recapitulating the pathological signatures of AC hearts. Using our AC model and samples from pathological human AC hearts, we show here that plakoglobin is a key component of Insulin-p85 metabolic signaling complex. Desmosome mutations lead to faster plakoglobin degradation, reduce PI3K/Akt activation, and hyperactivate GSK3β, which downregulate a microRNA (miR) cluster leading to subsequent abnormal PPARγ activation and CM apoptosis. Importantly, we used genetic and cellular methods to confirm the clinically relevance of our pathogenic pathways in human AC hearts and in mouse models of AC. We propose here to further elucidate the dysregulated and non-junctional signaling networks caused by plakoglobin deficits, to study how plakophilin-2 deficits deregulate additional signaling pathways, and to find clinically safe therapeutic agents for treating AC using both in vitro iPSC-CM based models and mouse models of AC.