Engineered Troponin C Constructs Correct Disease-related Cardiac Myofilament Calcium Sensitivity
Engineered Troponin C Constructs Correct Disease-related Cardiac Myofilament Calcium Sensitivity
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DOI：
10.1074/jbc.m111.334953
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发表时间：
2012-06-08
影响因子：
4.8
通讯作者：
Davis, Jonathan P.
中科院分区：
文献类型：
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作者：
Liu, Bin;Lee, Ryan S.;Davis, Jonathan P.
肌丝钙敏感性异常常见于多种心脏疾病，尤其是家族性心肌病。虽然心肌病的病因尚不清楚，但通过药物或遗传方法改善心肌钙敏感性有望缓解与疾病相关的症状。由于肌钙蛋白C(TNC)作为心肌收缩的钙感受器的中心作用，使疾病相关的肌丝对钙的敏感性恢复到正常水平，是一个明显且多功能的靶点。为了验证通过合理设计TNC结构可以纠正异常的肌丝钙敏感性及其相关功能的假设，我们研究了代表不同蛋白质(肌钙蛋白I或肌钙蛋白T)、修饰(错义突变、缺失或截断)和疾病亚型(家族性或获得性)的三种细丝蛋白修饰。在重组细丝的生理相关生化模型体系中，利用荧光TNC测定了TNC与钙离子的结合。与病理生理学一致的是，限制性心肌病突变肌钙蛋白I R192H和缺血诱导的肌钙蛋白I截断(残基1-192)增加了TNC对细丝上的钙敏感性，而扩张型心肌病突变TnC T Delta K210降低了TNC对细丝上的钙敏感性。合理设计的TNC结构纠正了细丝对钙的异常敏感性，重组的肌球蛋白ATPase活性，以及皮肤小梁中的力产生。因此，本研究提供了一种新的和通用的治疗策略，以恢复患病的心肌钙敏感性。
Aberrant myofilament Ca2+ sensitivity is commonly observed with multiple cardiac diseases, especially familial cardiomyopathies. Although the etiology of the cardiomyopathies remains unclear, improving cardiac muscle Ca2+ sensitivity through either pharmacological or genetic approaches shows promise of alleviating the disease-related symptoms. Due to its central role as the Ca2+ sensor for cardiac muscle contraction, troponin C (TnC) stands out as an obvious and versatile target to reset disease-associated myofilament Ca2+ sensitivity back to normal. To test the hypothesis that aberrant myofilament Ca2+ sensitivity and its related function can be corrected through rationally engineered TnC constructs, three thin filament protein modifications representing different proteins (troponin I or troponin T), modifications (missense mutation, deletion, or truncation), and disease subtypes (familial or acquired) were studied. A fluorescent TnC was utilized to measure Ca2+ binding to TnC in the physiologically relevant biochemical model system of reconstituted thin filaments. Consistent with the pathophysiology, the restrictive cardiomyopathy mutation, troponin I R192H, and ischemia-induced truncation of troponin I (residues 1-192) increased the Ca2+ sensitivity of TnC on the thin filament, whereas the dilated cardiomyopathy mutation, troponin T Delta K210, decreased the Ca2+ sensitivity of TnC on the thin filament. Rationally engineered TnC constructs corrected the abnormal Ca2+ sensitivities of the thin filament, reconstituted actomyosin ATPase activity, and force generation in skinned trabeculae. Thus, the present study provides a novel and versatile therapeutic strategy to restore diseased cardiac muscle Ca2+ sensitivity.