A Premature Termination Codon Mutation in MYBPC3 Causes Hypertrophic Cardiomyopathy via Chronic Activation of Nonsense-Mediated Decay
A Premature Termination Codon Mutation in MYBPC3 Causes Hypertrophic Cardiomyopathy via Chronic Activation of Nonsense-Mediated Decay
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DOI：
10.1161/circulationaha.118.034624
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发表时间：
2019-02-05
期刊：
影响因子：
37.8
通讯作者：
Wu, Joseph C.
中科院分区：
文献类型：
--
作者：
Seeger, Timon;Shrestha, Rajani;Wu, Joseph C.
背景技术背景：肥厚型心肌病（HCM）通常由肌球蛋白结合蛋白C3（MYBPC 3）突变导致提前终止密码子（PTC）引起。MYBPC 3中PTC突变如何导致HCM的发生和进展的潜在机制尚不清楚。本研究的目的是通过利用人等基因诱导多能干细胞衍生的心肌细胞（iPSC-CMs）来研究与MYBPC 3 PTC突变相关的HCM发病机制的分子机制。方法：使用基因组编辑从携带MYBPC 3 PTC突变（p.R943x; p.R1073P_Fsx4）的HCM患者产生等基因iPSC系。在iPSC-CMs.RESULTS中进行了全面的表型和转录组分析：我们观察到异常的钙处理特性，与同基因对照相比，在HCM iPSC-CMs中没有结构异常或收缩功能障碍的情况下，具有延长的衰变动力学和升高的舒张期钙水平。MYBPC 3的mRNA表达水平在突变iPSC-CM中显著降低，但蛋白水平在同基因iPSC-CM中相当，表明MYBPC 3的单倍不足并不有助于体外HCM的发病。此外，未检测到截短的MYBPC 3肽。在分子水平上，无义介导的衰变途径被激活，并且参与主要心脏信号传导途径的一组基因在HCM iPSC-CM中失调，表明体外HCM基因签名。特异性抑制突变iPSC-CM中无义介导的衰变途径导致分子表型逆转和钙处理异常的正常化。结论：携带MYBPC 3 PTC突变的iPSC-CM在没有显著的MYBPC 3蛋白单倍不足的情况下显示异常的钙信号传导和分子失调。在这里，我们提供了慢性激活的无义介导的衰变途径和HCM疾病发展之间直接联系的第一个证据。
BACKGROUND: Hypertrophic cardiomyopathy (HCM) is frequently caused by mutations in myosin-binding protein C3 (MYBPC3) resulting in a premature termination codon (PTC). The underlying mechanisms of how PTC mutations in MYBPC3 lead to the onset and progression of HCM are poorly understood. This study's aim was to investigate the molecular mechanisms underlying the pathogenesis of HCM associated with MYBPC3 PTC mutations by utilizing human isogenic induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs).METHODS: Isogenic iPSC lines were generated from HCM patients harboring MYBPC3 PTC mutations (p.R943x; p.R1073P_Fsx4) using genome editing. Comprehensive phenotypic and transcriptome analyses were performed in the iPSC-CMs.RESULTS: We observed aberrant calcium handling properties with prolonged decay kinetics and elevated diastolic calcium levels in the absence of structural abnormalities or contracile dysfunction in HCM iPSC-CMs as compared to isogenic controls. The mRNA expression levels of MYBPC3 were significantly reduced in mutant iPSC-CMs, but the protein levels were comparable among isogenic iPSC-CMs, suggesting that haploinsufficiency of MYBPC3 does not contribute to the pathogenesis of HCM in vitro. Furthermore, truncated MYBPC3 peptides were not detected. At the molecular level, the nonsense-mediated decay pathway was activated, and a set of genes involved in major cardiac signaling pathways was dysregulated in HCM iPSC-CMs, indicating an HCM gene signature in vitro. Specific inhibition of the nonsense-mediated decay pathway in mutant iPSC-CMs resulted in reversal of the molecular phenotype and normalization of calcium-handling abnormalities.CONCLUSIONS: iPSC-CMs carrying MYBPC3 PTC mutations displayed aberrant calcium signaling and molecular dysregulations in the absence of significant haploinsufficiency of MYBPC3 protein. Here we provided the first evidence of the direct connection between the chronically activated nonsense-mediated decay pathway and HCM disease development.