Myofilaments as regulators of heart function in disease

摘要 缺血性心肌病和心力衰竭是老年人合并发病率和死亡率的主要原因。 人类遗传性和获得性心肌病患者的临床管理具有挑战性 并受到新疗法稀缺的限制。该提案的直接重点是机械性 深入了解肌节调节和心脏性能，长期目标是最终推进新的 治疗心脏病的方法。这一努力强调了这一建议的重大健康相关性。 心脏肌节是驱动心脏收缩的复杂的变构调节系统，但一直被认为是心脏收缩的重要因素。 作为心脏疾病的治疗靶点，其研究显著不足。几十年来，心脏领域 认为细胞内Ca 2+处理是调节健康和疾病中心脏性能的关键途径。 相比之下，较少强调肌节在控制心脏性能中的作用， 这意味着巨大的差距和错失的机会。到目前为止，该领域的一个主要限制是， 不能直接监测活心肌细胞中肌节激活。肌节的表现一直是 在真实的时间内检测活的完整肌细胞中的肌丝激活方面，“黑匣子”。我们在这里利用 方法上的突破使得能够实时检测活心肌细胞中的肌节激活。 这一创新将引导我们对肌节在健康中的功能进行机械驱动的研究， 疾病，包括阐明肌节活化配体的作用。利用这种基于FRET的肌节 激活平台，我们独特地准备定义的调节作用的生理意义， 活细胞中的肌节。用活细胞阐明心肌肌节调节的基本特性 记录，我们在一个独特的位置，以测试假设，肌节功能是解耦的钙 在遗传性和获得性心肌病模型中的处理，指出肌节是 实验性的治疗发现通过整合三个互补的目标，我们将确定 基于肌节的兴奋-收缩解偶联的分子机制，并研究其影响 由于肌球蛋白、肌钙蛋白和小分子的疾病引起的活细胞肌节激活， 心肌这一建议将推进对心脏性能调节的新理解， 在肌节调节基因、蛋白质和小分子方面取得潜在突破的大门， 影响健康和疾病中心脏性能。

Abstract Ischemic cardiomyopathy and heart failure are the leading causes of combined morbidity and mortality in humans. Clinical management of patients with inherited and acquired forms of cardiomyopathy is challenging and limited by the scarcity of new therapies in the pipeline. This proposal's immediate focus is on mechanistic insights into sarcomere regulation and heart performance with the long-term goal to ultimately advance novel approaches to redress heart disease. This effort underscores the significant health relevance of this proposal. The cardiac sarcomere is a complex allosteric regulatory system that drives heart contraction, but has been significantly under studied as a therapeutic target for cardiac disorders. For decades, the cardiac field has considered intracellular Ca2+ handling as the key pathway regulating heart performance in health and disease. By contrast, less emphasis has been placed on the role of the sarcomere in governing heart performance, representing a significant gap and missed opportunity. Until now, a major limitation in the field has been the inability to directly monitor sarcomere activation in live cardiac myocytes. Sarcomere performance has been a "black box" in terms of detecting, in real time, myofilament activation in live intact myocytes. We leverage here a methodological breakthrough enabling real-time detection of sarcomere activation in live cardiac myocytes. This innovation will lead our mechanistically-driven studies on the function of the sarcomere in health and disease, including elucidating the roles of sarcomeric activating ligands. Using this FRET-based sarcomere activation platform, we are uniquely poised to define the physiological significance of the regulatory role of the sarcomere in live cells. In illuminating fundamental properties of cardiac sarcomere regulation using live cell recordings, we are in a unique position to test the hypothesis that sarcomere function is uncoupled from Ca2+ handling in models of inherited and acquired cardiomyopathy, pointing to the sarcomere as a key target for experimental therapeutic discoveries. By the integration of three complementary Aims, we will determine the molecular mechanism underlying sarcomere-based excitation-contraction uncoupling and investigate the effects on live cell sarcomere activation due to disease causing mutations in myosin, troponin and small molecules in cardiac muscle. This proposal will advance a new understanding of heart performance regulation and open the door to potential breakthroughs in sarcomere modulating genes, proteins and small molecules to positively impact heart performance in health and disease.