Department of Physiology, Biophysics and Systems Biology, Technion, Haifa, Israel.
The Rappaport Institute, Haifa, Israel.
PLoS One. 2018 Oct 17;13(10):e0205719. doi: 10.1371/journal.pone.0205719. eCollection 2018.
Dilated cardiomyopathy (DCM), a myocardial disorder that can result in progressive heart failure and arrhythmias, is defined by ventricular chamber enlargement and dilatation, and systolic dysfunction. Despite extensive research, the pathological mechanisms of DCM are unclear mainly due to numerous mutations in different gene families resulting in the same outcome-decreased ventricular function. Titin (TTN)-a giant protein, expressed in cardiac and skeletal muscles, is an important part of the sarcomere, and thus TTN mutations are the most common cause of adult DCM. To decipher the basis for the cardiac pathology in titin-mutated patients, we investigated the hypothesis that induced Pluripotent Stem Cell (iPSC)-derived cardiomyocytes (iPSC-CM) generated from patients, recapitulate the disease phenotype. The hypothesis was tested by 3 Aims: (1) Investigate key features of the excitation-contraction-coupling machinery; (2) Investigate the responsiveness to positive inotropic interventions; (3) Investigate the proteome profile of the AuP cardiomyocytes using mass-spectrometry (MS).
iPSC were generated from the patients' skin fibroblasts. The major findings were: (1) Sarcomeric organization analysis in mutated iPSC-CM showed defects in assembly and maintenance of sarcomeric structure. (2) Mutated iPSC-CM exhibited diminished inotropic and lusitropic responses to β-adrenergic stimulation with isoproterenol, increased [Ca2+]out and angiotensin-II. Additionally, mutated iPSC-CM displayed prolonged recovery in response to caffeine. These findings may result from defective or lack of interactions of the sarcomeric components with titin through its kinase domain which is absent in the mutated cells.
These findings show that the mutated cardiomyocytes from DCM patients recapitulate abnormalities of the inherited cardiomyopathies, expressed as blunted inotropic response.
扩张型心肌病（DCM）是一种心肌疾病，可导致进行性心力衰竭和心律失常，其特征为心室腔扩大和扩张以及收缩功能障碍。尽管进行了广泛的研究，但 DCM 的病理机制仍不清楚，主要是因为不同基因家族的许多突变导致相同的结果-心室功能降低。肌联蛋白（TTN）-一种在心肌和骨骼肌中表达的巨大蛋白，是肌节的重要组成部分，因此 TTN 突变是成人 DCM 的最常见原因。为了解释 TTN 突变患者的心脏病理学基础，我们研究了以下假说：即诱导多能干细胞（iPSC）衍生的心肌细胞（iPSC-CM）源自患者，可重现疾病表型。该假说通过以下 3 个目的进行了测试：（1）研究兴奋-收缩偶联机制的关键特征；（2）研究对正性变力干预的反应性；（3）使用质谱法（MS）研究 AuP 心肌细胞的蛋白质组谱。
从患者的皮肤成纤维细胞中生成 iPSC。主要发现包括：（1）突变的 iPSC-CM 的肌节组织分析显示肌节结构的组装和维持存在缺陷。（2）突变的 iPSC-CM 对异丙肾上腺素的β-肾上腺素能刺激表现出减弱的变力和变时反应，增加[Ca2+]out 和血管紧张素-II。此外，突变的 iPSC-CM 对咖啡因的反应显示恢复时间延长。这些发现可能是由于肌节成分与肌联蛋白通过其激酶结构域的相互作用缺陷或缺失引起的，而突变细胞中缺乏该结构域。
这些发现表明，DCM 患者的突变心肌细胞再现了遗传性心肌病的异常，表现为变力反应减弱。
Zotero 插件