Myofilaments as regulators of heart function in disease

摘要 缺血性心肌病和心力衰竭是#年发病率和死亡率的主要原因。 人类。因此，肌节功能障碍在疾病的发病机制中起着核心作用。肌节是 心肌的基本功能单位，直接负责心脏的泵血活动。心脏 肌节是一种由以肌丝为基础的变构调节器组成的多聚体收缩装置 与肌球蛋白为基础的可产生力量的粗大肌丝结合在一起。交织肌丝 同步运行，以调节和产生心脏功能所需的力量。逐拍控制 心肌肌节激活的程度是指细丝调节系统在控制状态的程度 它的收缩在抽搐时开启和关闭。肌节功能的破坏是导致 各种形式的获得性和遗传性心脏病影响着这个国家的数百万人。因此，焦点 在这里，对肌节调节的机械论见解强调了这一提议的主要健康相关性。 最近，关于肌丝间调控信号协同作用的新结果已经显露端倪。 机制，包括肌球蛋白跨桥开/关状态在控制肌肉收缩中的新作用。 基于我们的肌节激活创新，以单个未加载的心肌细胞为特色，我们已经做出了 突破性的方法学进步，允许实时记录完整心脏的肌节激活 生理负荷下的肌肉。该系统能够通过分子内FRET检测多个 在体心脏单次抽动收缩生理过程中肌丝激活的配体 肌肉负重。指导性假设：在负荷下生理相关的抽动收缩过程中，变薄 细丝激活由多个协同的肌丝间调节输入动态控制，包括 TNC结合钙离子，TnI开关域-TNC相互作用，关闭到开启状态的肌球蛋白跨桥，以及活体中的MyBP-C 心肌。这项建议旨在通过改变TnI分子开关来研究肌丝间信号转导 负荷状态下活体心肌单次心脏抽动的生理时程机制 活体心脏痉挛收缩时肌丝间信号转导机制的研究 通过肌球蛋白交叉桥修饰心肌；并研究MyBP-C在肌丝间的作用 完整心肌生理性抽动收缩时的信号。在我们的创新方法的推动下， 在这里获得的对肌丝间信号机制的新见解将显著影响我们的 对心脏功能的了解。反过来，这又为指导新的治疗方法提供了必要的基础 通过利用肌节作为开发新的新的优秀靶点来发现患病的心脏 心脏疾病的治疗和治疗。

Abstract Ischemic cardiomyopathy and heart failure are the leading causes of combined morbidity and mortality in humans. Herein, sarcomere dysfunction has a central role in disease pathogenesis. The sarcomere is the essential functional unit of cardiac muscle, directly responsible for the pumping action of the heart. The cardiac sarcomere is a multimeric contractile apparatus consisting of a thin myofilament-based allosteric regulatory complex together with the myosin-based thick myofilament that generates force. Interlacing myofilaments operate in synchrony to regulate and generate the forces necessary for heart performance. Beat-to-beat control of cardiac sarcomere activation refers to the status of the thin filament regulatory system in controlling the degree to which contraction is turned on and off during a twitch. Disruption in sarcomere function underlies the basis for numerous forms of acquired and inherited heart diseases affecting millions of people in this country. Thus, focus here on mechanistic insights into sarcomere regulation underscores the major health relevance of this proposal. Recently, emerging results have come to the fore positing synergistic inter-myofilament regulatory signaling mechanisms, including a new role of myosin cross-bridge ON/OFF states in controlling muscle contraction. Building on our sarcomere activation innovations featuring single unloaded cardiac myocytes, we have made a breakthrough methodological advance, permitting real-time recordings of sarcomere activation in intact cardiac muscle under physiological load. This system is capable of detecting, by intramolecular FRET, multiple myofilament activating ligands during the physiological time course of a single twitch contraction in intact cardiac muscle under load. Guiding hypothesis: During physiologically relevant twitch contractions under load, thin filament activation is controlled dynamically by multiple synergistic inter-myofilament regulatory inputs, including TnC bound Ca2+, TnI switch domain-TnC interaction, OFF to ON state myosin cross-bridges, and MyBP-C in live cardiac muscle. This proposal aims to investigate inter-myofilament signaling by altering the TnI molecular switch mechanism during the physiological time-course of a single cardiac twitch in live cardiac muscles under load; to investigate the mechanism of inter-myofilament signaling during the cardiac twitch contraction in live intact cardiac muscles by modification in myosin cross-bridges; and to investigate the role MyBP-C in inter-myofilament signaling during physiological twitch contractions in intact cardiac muscles. Enabled by our innovative approach, the new insights into inter-myofilament signaling mechanisms gained here will significantly impact our understanding of cardiac function. In turn, this provides the essential foundation to guide new therapeutic discovery for the diseased heart by leveraging the sarcomere as an excellent target for developing new treatments and therapies for the diseased heart.