Patient mutations linked to arrhythmogenic cardiomyopathy enhance calpain-mediated desmoplakin degradation
Patient mutations linked to arrhythmogenic cardiomyopathy enhance calpain-mediated desmoplakin degradation
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DOI：
10.1172/jci.insight.128643
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发表时间：
2019-07-25
期刊：
影响因子：
8
通讯作者：
Campbell, Stuart G.
中科院分区：
文献类型：
--
作者：
Ng, Ronald;Manring, Heather;Campbell, Stuart G.
致心律失常性心肌病（ACM）是一种遗传性疾病，具有不同的遗传病因。在这里，我们专注于了解DSP的一个临床变异的精确分子病理学，编码桥粒斑蛋白的基因。我们最初在诊断为双心室ACM的患者中发现了一种潜在的新型错义桥粒斑蛋白变体（p.R451G）。一个广泛的单家族ACM队列组装，揭示了R451G桥粒斑蛋白和ACM表型的共遗传模式。使用患者来源的诱导多能干细胞系的体外模型系统显示在不存在异常电传播的情况下桥粒斑蛋白水平降低。桥粒斑蛋白R451G的分子动力学模拟显示没有明显的结构变化，但观察到一个假定的钙蛋白酶靶位点周围的分子内相互作用的显着损失。重组桥粒斑蛋白R451G的蛋白质降解测定证实了钙蛋白酶脆弱性增加。计算机筛选确定了3个额外的ACM连锁桥粒斑蛋白错义突变的子集，具有明显增强的钙蛋白酶易感性，实验证实了预测。与R451G类似，这些突变也见于双心室ACM家族。我们的结论是，增强钙蛋白酶介导的降解桥粒斑蛋白代表了一个共同的病理机制选择ACM连锁的错义变异。这种识别具有共同分子病理学的变体的方法可能代表了理解和治疗遗传性心肌病的强大新策略。
Arrhythmogenic cardiomyopathy (ACM) is an inherited disorder with variable genetic etiologies. Here, we focused on understanding the precise molecular pathology of a single clinical variant in DSP, the gene encoding desmoplakin. We initially identified a potentially novel missense desmoplakin variant (p.R451G) in a patient diagnosed with biventricular ACM. An extensive single-family ACM cohort was assembled, revealing a pattern of coinheritance for R451G desmoplakin and the ACM phenotype. An in vitro model system using patient-derived induced pluripotent stem cell lines showed depressed levels of desmoplakin in the absence of abnormal electrical propagation. Molecular dynamics simulations of desmoplakin R451G revealed no overt structural changes, but a significant loss of intramolecular interactions surrounding a putative calpain target site was observed. Protein degradation assays of recombinant desmoplakin R451G confirmed increased calpain vulnerability. In silico screening identified a subset of 3 additional ACM-linked desmoplakin missense mutations with apparent enhanced calpain susceptibility, predictions that were confirmed experimentally. Similar to R451G, these mutations are found in families with biventricular ACM. We conclude that augmented calpain-mediated degradation of desmoplakin represents a shared pathological mechanism for select ACM-linked missense variants. This approach for identifying variants with shared molecular pathologies may represent a powerful new strategy for understanding and treating inherited cardiomyopathies.