The myosin light chain regulators of heart function

心脏功能的肌球蛋白轻链调节因子

• 批准号: 10009818
• 负责人: Danuta Szczesna-Cordary
• 金额: $ 48.75万
• 依托单位: UNIVERSITY OF MIAMI SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-20 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10009818
• 关键词: Actins; Address; Affect; Animal Model; Binding; Bioenergetics; Biological Assay; Cardiac; Cardiac Muscle Contraction; Cardiac Myosins; Cardiomyopathies; Complex; Data; Disease; Echocardiography; Equilibrium; Event; Exhibits; Fluorescence; Fluorescence Resonance Energy Transfer; Frequencies; Genes; Head; Health; Heart; In Vitro; Kinetics; Label; Left; Light; Mass Spectrum Analysis; Measurement; Microfilaments; Mitochondria; Modeling; Molecular; Motor; Mus; Muscle; Muscle Contraction; Muscle Fibers; Mutation; Myocardium; Myosin ATPase; Myosin Light Chains; N-terminal; Output; Pathology; Phenotype; Phosphorylation; Phosphorylation Site; Play; Power stroke; Process; Production; Quantum Dots; RNA Splicing; Regulation; Respiration; Respiratory Chain; Role; Severities; Skeletal Muscle; Skin; Smooth Muscle; Stress; Striated Muscles; Tail; Thick Filament; Thin Filament; Time; Tissues; Transgenic Organisms; Variant; Ventricular; Work; base; cell motility; design; heart function; hemodynamics; in vivo; insight; metabolic rate; mouse model; new therapeutic target; novel; papillary muscle; phosphoproteomics; pressure; response

ABSTRACT The myosin essential (ELC) and regulatory (RLC) light chains play important roles in cardiac muscle contraction, yet their specific roles in regulating myosin motor function are not well understood. The scientific premise of this application regards the role of two myosin light chain (MLC) regulators that modulate myosin motor function in vivo and in vitro: (1) the long N-terminus of cardiac ELC (N-ELC), and (2) cardiac myosin RLC phosphorylation (P-RLC). Mouse models of cardiomyopathy (HCM, RCM and DCM) along with N-terminally truncated ELC-Δ43 mice will be studied to fully comprehend the mode of action of these two myosin regulators in controlling cardiac muscle contraction in health and disease. The study question addressed here is how N-ELC and P-RLC work at the molecular, myofilament and whole heart levels? Our central hypothesis is that MLC regulators function as molecular and/or energetic triggers controlling myosin’s power stroke, ATP utilization and force production in cardiac muscle. AIM 1: THE ROLE OF N-ELC AND P-RLC IN THE REGULATION OF MYOSIN MOTOR FUNCTION IN DIFFERENT MODELS OF CARDIOMYOPATHY. This aim will focus on the molecular triggers and MLC regulators of heart remodeling at the level of myosin molecules. Hypothesis: N-ELC uses a novel mechanism of step-size and step- frequency modulation to control cardiac myosin power output and facilitate actin-myosin interaction, and this process is regulated by P-RLC. We will investigate whether and how HCM/RCM/DCM/Δ43 mutations in MLC regulate myosin ATP-turnover rates and affect the super-relaxed (SRX)↔ relaxed (DRX) equilibrium in the heart. AIM 2: INTERROGATE MLC-REGULATED MYOSIN MOTOR FUNCTION AND HEMODYNAMIC, CONTRACTILE AND ENERGETIC RESPONSES OF THE HEART. Mechanistic studies of Aim 1 and MLC-dependent alterations in myosin motor function will be integrated with the hemodynamic, contractile and energetic responses of the heart in vivo. Hypothesis: HCM, RCM, DCM and Δ43 hearts exhibit different demands for ATP to sustain their hemodynamic and contractile functions in vivo, thus differently affecting mitochondrial bioenergetics. AIM 3: ASSESS PHOSPHORYLATION OF MYOSIN RLC AND ELC AS A MOLECULAR MECHANISM TO MITIGATE THE PATHOLOGY OF HCM, RCM AND DCM. The cardiac SRX serves as a modulator of cardiac energy utilization, involved in decreasing metabolic rate (load) in both, the normally functioning myocardium and during times of stress, e.g. cardiomyopathy. Hypothesis: Phosphorylation of myosin RLC, and possibly ELC, play a potential protective role in cardiomyopathy disease that involve alterations of the SRX state and the phosphorylation- induced shift in the super-relaxed (SRX) ↔ disordered relaxed (DRX) equilibrium toward the DRX state in which myosin heads can readily interact with thin filaments and produce force.

抽象的 肌球蛋白必需（ELC）和调节（RLC）轻链在心肌收缩中起重要作用， 然而，他们在确定肌球蛋白运动功能方面的特定作用尚不清楚。科学前提 该应用程序考虑了调节肌球蛋白运动功能的两个肌球蛋白轻链（MLC）调节器的作用 体内和体外：（1）心脏ELC（N-ELC）的长N端和（2）心脏肌球蛋白RLC磷酸化 （P-RLC）。心肌病的小鼠模型（HCM，RCM和DCM）以及N末端截断的ELC-Δ43 小鼠将研究以完全理解这两个肌球蛋白调节剂控制心脏的作用方式 健康和疾病的肌肉收缩。这里解决的研究问题是N-ELC和P-RLC如何工作 分子，肌丝和整个心脏水平？我们的中心假设是MLC调节剂充当 分子和/或能量触发器控制肌球蛋白的动力中风，ATP利用和强制产生 心肌。 AIM 1：N-ELC和P-RLC在不同的肌球蛋白运动功能中的作用 心肌病模型。这个目标将重点放在心脏的分子触发器和MLC调节器上 在肌球蛋白分子的水平上进行重塑。假设：N-ELC使用了一种新型的阶梯和阶跃机制 控制心脏肌球蛋白功率输出并促进肌动蛋白肌球蛋白相互作用的频率调节，这 过程由P-RLC调节。我们将研究MLC中的HCM/RCM/RCM/DCM/δ43突变 调节肌球蛋白ATP转变率，并影响心脏中超级省的（SRX）↔宽松（DRX）。 AIM 2：询问MLC调节的肌球蛋白运动功能和血液动力学，收缩和 心脏充满活力的反应。 AIM 1和MLC依赖性改变的机械研究 肌球蛋白运动功能将与心脏的血液动力学，收缩和能量反应集成 体内。假设：HCM，RCM，DCM和δ43心暴露了对ATP的不同要求 血液动力学和收缩功能在体内功能，因此影响线粒体生物能学的影响不同。 目标3：评估肌球蛋白RLC和ELC的磷酸化作为减轻分子机制 HCM，RCM和DCM的病理。心脏SRX充当心脏能量利用的调节剂， 涉及降低两者的代谢率（负载），正常运作的心肌以及 压力，例如心肌病。假设：肌球蛋白RLC和可能的ELC的磷酸化作用 在心肌病疾病中的保护作用，涉及SRX状态和磷酸化的改变 - 诱导超浮标（SRX）的转移dry的降低（DRX）等效于DRX状态 肌球蛋白头可以很容易与细丝相互作用并产生力。