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Troponin and myosin in regulation of muscle contraction and heart disease

肌钙蛋白和肌球蛋白调节肌肉收缩和心脏病

基本信息

批准号：
8197235
负责人：
Zenon Grabarek
金额：
$ 50.24万
依托单位：
BOSTON BIOMEDICAL RESEARCH INSTITUTE
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-12-15 至 2013-03-01
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8197235
关键词：
ATP phosphohydrolase Actins Actomyosin Adenosinetriphosphatase Affect Affinity Binding C-terminal Cardiac Cessation of life Complement Complex Contractile Proteins Data Disease Disulfides Divalent Cations Drug Design Equilibrium Familial Hypertrophic Cardiomyopathy Fiber Fluorescence Resonance Energy Transfer Goals Head Heart Diseases Heart Hypertrophy Kinetics Label Lead Measurement Modeling Molecular Muscle Contraction Muscle Fibers Muscle function Mutation Myocardium Myosin ATPase Play Process Protein Isoforms Proteins Quality of life Regulation Relative (related person)Role Signal Transduction Skeletal Muscle Solutions Stretching Structure System Techniques Testing Thin Filament Titrations Tropomyosin Troponin Troponin C Troponin I actin-S1 base crosslink genetic regulatory protein mutant novel premature protein protein interaction reconstitution reconstruction research study response tool

项目摘要

A number of familial hypertrophic cardiomyopathy (FHC) causing mutations have been identified in the regulatory proteins, tropomyosin (Tm) and troponin (Tn). Most of these mutations cause an increase in the Ca2+-sensitivity of muscle contraction, i.e. the onset of force occurs at lower Ca2+ concentrations. Neither the molecular mechanisms underlying the increased Ca2+-sensitivity nor its relation to the hypertrophy of the heart are well understood. Stretch activation is another cardiac phenomenon whose molecular mechanism is not understood. The long-range goal is to understand the molecular basis of FHC and stretch activation. The main hypothesis that we will test is that both of these activations involve strongly bound cross bridges (myosin heads). We plan to: 1. Determine the contribution of the myosin head-induced vs. Ca2+-induced changes in the interactions of troponin I (TnI) with actin-Tm and with troponin C (TnC) in thin filaments reconstituted with skeletal and cardiac muscle isoforms of the regulatory proteins. The main techniques will be solution ATPase and FRET measurements. 2. Determine effects of FHC mutations on occupancy of the 3 thin filament regulatory states using equilibrium titrations and transient kinetics. Fluorescent labels on selected proteins will be used to obtain equilibrium constants and rates. 3. Determine effects of selected FHC mutations in TnI and Tm on ATPase in terms of myosin vs. Ca2+ activation. FRET measurements will be used to obtain structural information. 4. Test the hypothesis that the C-terminal domain of TnC is involved in the myosin head induced activation of the thin filament. Mutants of TnC having increased affinity for Mg2+ will be used to assess the role of divalent cation in the C-domain of TnC on thin filament function. A novel mutant of TnC which reconstitutes into the thin filament and binds Ca2+ but does not activate ATPase that was developed in this lab will be used. These experiments will lead to a better understanding of the regulatory mechanism in cardiac and skeletal muscle. In particular, a better understanding of the relative contribution of the Ca2+/troponin-dependent and the myosin S1/actin-dependent activation of the thin filament will be obtained. By identifying the protein-protein interactions that are altered in the disease state it will be possible to suggest potential targets for drug design for FHC.

一些家族性肥厚型心肌病（FHC）引起的突变已经被发现，在调节蛋白原肌球蛋白（Tm）和肌钙蛋白（Tn）中鉴定。大多数这些突变导致肌肉收缩的Ca2+敏感性增加，即力的开始发生在较低的Ca2+浓度下。无论是潜在的分子机制， Ca2+敏感性的增加及其与心脏肥大的关系是很好理解的。牵张激活是另一种心脏现象，其分子机制不是明白长期目标是了解FHC和拉伸的分子基础 activation.我们将检验的主要假设是，这两种激活都强烈涉及结合横桥（肌球蛋白头）。我们计划： 1.确定肌球蛋白头诱导的与Ca2+诱导的变化在心肌细胞中的作用。肌钙蛋白I（TnI）与肌动蛋白Tm和肌钙蛋白C（TnC）在细丝中的相互作用用调节蛋白的骨骼肌和心肌同种型重建。主要技术将是溶液ATP酶和FRET测量。 2.确定FHC突变对3种细丝调节状态占据率的影响使用平衡滴定和瞬态动力学。在选定的蛋白质上的荧光标记将被用于获得平衡常数和速率。 3.确定TnI和Tm中选定的FHC突变对ATP酶的影响，肌球蛋白与Ca2+激活。FRET测量将用于获得结构信息。 4.检验TnC的C末端结构域参与肌球蛋白头的假设引发细灯丝的激活。对Mg2+具有增加的亲和力的TnC突变体将被用于评估TnC C结构域中二价阳离子对细丝功能的作用。一种新的TnC突变体，其重组为细丝并结合Ca 2+，但不将使用本实验室开发的不活化ATP酶。这些实验将导致更好地了解心肌和骨骼肌的调节机制。在特别是，更好地了解钙离子/肌钙蛋白依赖性和将获得肌球蛋白S1/肌动蛋白依赖的细丝激活。通过识别蛋白质-蛋白质相互作用在疾病状态下发生改变，这将可能表明 FHC药物设计的潜在目标。