以“病人特异性”诱导多能干细胞来源的心肌细胞为模型研究TMEM43基因突变引起致心律失常性右室心肌病的分子机制

Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetic cardiomyopathy characterized by hypokinetic areas involving the free wall of the right ventricle with fibrofatty replacement of the right ventricular myocardium, leading to enlarged ventricle, severe arrhythmias and sudden cardiac death, which is a serious threat to human health. It has been reported that TMEM43 is an ARVC-associated gene since 2008, however, little is known about the function of TMEM43, and little is known about how TMEM43 gene mutation causing ARVC. We have successfully recruited 1 ARVC patient carrying TMEM43 gene mutation as well as 3 healthy control subjects. Using induced pluripotent stem cell (iPSC) model, we have performed functional tests and our preliminary data demonstrated clear disease phenotype including increased lipidosis and arrhythmias, and significantly differential NF-κB and calcium signaling pathways in ARVC patient-specific iPSC-derived cardiomyocytes (iPSC-CMs), as compared to control cells. In this project, taking advantage of established iPSC model, we will reveal the disease phenotype of ARVC, and elucidate the role of TMEM43 in regulating cardiac function; we will then confirm and validate the regulatory role of TMEM43 in ARVC pathogenesis, screen ARVC-related gene targets that are associated with TMEM43, and deeply analyze down-stream signaling pathways. We believe this project will fully elucidate the role of TMEM43 gene mutation in ARVC pathogenesis and its underlying mechanism, which will provide new clues for developing new diagnosis and/or treatment approaches for ARVC.

致心律失常性右室心肌病（ARVC）是一种遗传性心肌病，以右室内心肌萎缩和纤维脂肪组织替代为特征，临床表现为心室扩大、恶性心律失常和心源性猝死，严重危害人民健康。跨膜蛋白43（TMEM43）是2008年发现的ARVC相关基因，但对于该基因的功能知之甚少，对于该基因突变如何引起ARVC疾病发生很不清楚。前期研究中我们入组了1例携带TMEM43突变的ARVC病人与3例健康受试者并应用诱导多能干细胞（iPSC）模型进行了初步的功能学研究，我们的预实验数据提示病人组心肌细胞出现脂性增加、心律失常等疾病表型，且NF-κB、钙调控等信号通路显著异常。本项目将应用建立的iPSC模型，揭示ARVC的功能学表型，明确TMEM43的功能，筛选ARVC发生中与TMEM43相关的靶基因和信号通路。通过以上研究，本项目将阐明TMEM43基因突变引起ARVC疾病发生的分子机制，为发展ARVC的诊断和治疗新方法打下基础。

致心律失常性右心室心肌病（Arrhythmogenic right ventricular cardiomyopathy, ARVC）是一种罕见的遗传性心肌病，该疾病以危及生命的心律失常为主要特征。尽管TMEM43已被确定为ARVC相关致病基因，但ARVC患者中TMEM43突变与心脏电生理异常之间的分子联系尚不明确。在本项目的研究中，我们发现一个新位点TMEM43突变（TMEM43-P386S）引起肌浆网（sarcoplasmic reticulum,SR）异常Ca2+释放，从而导致ARVC患者来源诱导多能干细胞衍生的心肌细胞（induced pluripotent stem cell-derived cardiomyocytes, iPSC-CMs）的心律失常表型。进一步分子机制机制研究表明，TMEM43与核膜蛋白lamin B2存在相互作用，TMEM43-P386S导致ARVC iPSC-CMs中lamin B2错误定位及核膜结构出现异常，并使得包括RYR2在内的下调基因周围启动子染色质开放区域减少。Tau-STED超分辨显微镜成像结果提示，ARVC iPSC-CMs中RYR2被下调，存在过度磷酸化并聚集成更小的簇，导致RYR2介导的SR Ca2+泄漏增强。最后，通过抗心律失常药物的氟卡因或CaMKII抑制剂KN93稳定RYR2活性有效挽救了ARVC iPSC-CMs的心律失常表型。这些发现展现了TMEM43相关ARVC心律失常事件发生增加的新机制及疾病干预的新策略。