C Protein and Cross Bridge Function in Heart Muscle

C 蛋白和心肌中的跨桥功能

基本信息

批准号：
6755129
负责人：
SAUL WINEGRAD
金额：
$ 35.66万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-01-01 至 2006-05-31
项目状态：
已结题

项目摘要

Myosin binding protein C (MyBP-C) is essential for the formation of normal thick filaments and sarcomeres: The fact that the cardiac isoform of MyBP-C contains 3 phosphorylation sites which are not present in the skeletal isoform suggests that variation of the effect of MyBP-C on the structure of the thick filament by phosphorylation may be a mechanism for the modulation of the contraction in cardiac muscle. Almost every transmitter-based physiological mechanism for altering contractility is accompanied by a change in phosphorylation of MyBP-C in the thick filament. Work completed during the current period of support has provided the first direct evidence for change in thick filament and cross bridge structure from protein kinase A-mediated phosphorylation of MyBP-C. The changes in structure induced by the phosphorylation are consistent with the alterations in function that accompany the phosphorylation. The proposed hypothesis is that phosphorylation of MyBP-C in the heart is a mechanism for modulating contractility by modifying the structure of the thick filament and altering the interaction of myosin cross bridges with thin filaments. Our specific aim is to combine physiological, biochemical, structural and genetic studies of isolated rat cardiac muscle to determine the molecular mechanisms involved in this regulation. Functional and structural changes will be measured in parallel with changes in phosphorylation by combining electron microscopy and optical diffraction to detect changes in structure of isolated individual thick filaments, x-ray diffraction to detect changes in structure in the intact filament lattice and in intact cells, and isoelectric focussing and Western blotting to determine the specific pattern of phosphorylation of MyBP-C. The effect in isolated heart muscle of replacement of the whole MyBP-C molecule with genetically produced segments of the molecule will be studied to elucidate the basis for its influence on filament structure. The effect of genetic abnormalities in MyBP-C that have been produced in transgenic mice on the structure and function of the thick filament will also be examined. An understanding of this regulatory mechanism is important because of its potential for playing an important role in the normal function of the heart. Abnormalities in its structure and function are responsible for one of the more common forms of Familial Hypertrophic Cardiomyopathy.

肌球蛋白结合蛋白C（MYBP-C）对于形成正常厚的细丝和肉瘤至关重要：MyBP-C的心脏同工型包含3个骨骼同工型中不存在的3个磷酸化位点，这表明MyBP-C对磷酸化的厚细胞结构的影响可能是对磷酸化的结构的变化。几乎所有基于发射机的生理机制改变了收缩力，都伴随着厚细丝中MYBP-C磷酸化的变化。在当前支持期间完成的工作为蛋白激酶A介导的MYBP-C的蛋白激酶A介导的磷酸化的厚细丝和跨桥结构的变化提供了第一个直接证据。磷酸化引起的结构变化与伴随磷酸化的功能变化一致。提出的假设是，MYBP-C在心脏中的磷酸化是一种通过修饰厚细丝的结构并改变肌球蛋白交叉桥与细丝薄细丝的相互作用来调节收缩力的机制。我们的具体目的是结合分离的大鼠心肌的生理，生化，结构和遗传研究，以确定该调节所涉及的分子机制。通过将电子显微镜和光学衍射与磷酸化的变化并行测量的功能和结构变化，以检测孤立的个体厚细丝的结构变化，X射线衍射以检测完整丝晶状体中结构的变化，完整的细胞中的结构变化，以及确定磷酸化的特定模式。将研究将整个MYBP-C分子替换为分子产生的分子段的孤立心肌的效果，以阐明其对细丝结构的影响的基础。也将检查在转基因小鼠中产生的MYBP-C中遗传异常对厚细丝的结构和功能的影响。对这种调节机制的理解非常重要，因为它具有在心脏正常功能中发挥重要作用的潜力。其结构和功能的异常是家族性心肌病的最常见形式之一。