Asimaki Angeliki, Kapoor Sudhir, Plovie Eva, Karin Arndt Anne, Adams Edward, Liu ZhenZhen, James Cynthia A, Judge Daniel P, Calkins Hugh, Churko Jared, Wu Joseph C, MacRae Calum A, Kléber André G, Saffitz Jeffrey E
Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA.
Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Harvard Stem Cell Institute, and Broad Institute of Harvard and MIT, Boston, MA 02115, USA.
Sci Transl Med. 2014 Jun 11;6(240):240ra74. doi: 10.1126/scitranslmed.3008008.
Arrhythmogenic cardiomyopathy (ACM) is characterized by frequent cardiac arrhythmias. To elucidate the underlying mechanisms and discover potential chemical modifiers, we created a zebrafish model of ACM with cardiac myocyte-specific expression of the human 2057del2 mutation in the gene encoding plakoglobin. A high-throughput screen identified SB216763 as a suppressor of the disease phenotype. Early SB216763 therapy prevented heart failure and reduced mortality in the fish model. Zebrafish ventricular myocytes that expressed 2057del2 plakoglobin exhibited 70 to 80% reductions in I(Na) and I(K1) current densities, which were normalized by SB216763. Neonatal rat ventricular myocytes that expressed 2057del2 plakoglobin recapitulated pathobiological features seen in patients with ACM, all of which were reversed or prevented by SB216763. The reverse remodeling observed with SB216763 involved marked subcellular redistribution of plakoglobin, connexin 43, and Nav1.5, but without changes in their total cellular content, implicating a defect in protein trafficking to intercalated discs. In further support of this mechanism, we observed SB216763-reversible, abnormal subcellular distribution of SAP97 (a protein known to mediate forward trafficking of Nav1.5 and Kir2.1) in rat cardiac myocytes expressing 2057del2 plakoglobin and in cardiac myocytes derived from induced pluripotent stem cells from two ACM probands with plakophilin-2 mutations. These observations pinpoint aberrant trafficking of intercalated disc proteins as a central mechanism in ACM myocyte injury and electrical abnormalities.
致心律失常性心肌病（ACM）的特征是频繁发生心律失常。为了阐明其潜在机制并发现潜在的化学修饰剂，我们创建了一种ACM斑马鱼模型，该模型在编码桥粒斑珠蛋白的基因中具有心肌细胞特异性表达的人类2057del2突变。高通量筛选确定SB216763为疾病表型的抑制剂。早期使用SB216763治疗可预防心力衰竭并降低鱼类模型的死亡率。表达2057del2桥粒斑珠蛋白的斑马鱼心室肌细胞的I(Na)和I(K1)电流密度降低了70%至80%，而SB216763可使其恢复正常。表达2057del2桥粒斑珠蛋白的新生大鼠心室肌细胞重现了ACM患者中观察到的病理生物学特征，所有这些特征均被SB216763逆转或预防。SB216763观察到的逆向重塑涉及桥粒斑珠蛋白、连接蛋白43和Nav1.5的明显亚细胞重新分布，但它们的总细胞含量没有变化，这表明蛋白质向闰盘转运存在缺陷。为了进一步支持这一机制，我们在表达2057del2桥粒斑珠蛋白的大鼠心肌细胞以及来自两名患有桥粒蛋白2突变的ACM先证者的诱导多能干细胞衍生的心肌细胞中观察到SB216763可逆的、异常的SAP97（一种已知介导Nav1.5和Kir2.1正向转运的蛋白质）亚细胞分布。这些观察结果指出闰盘蛋白的异常转运是ACM心肌细胞损伤和电异常的核心机制。
