Troponin structure & function in cardiomyopathy

肌钙蛋白结构

• 批准号: 7239503
• 负责人: Jian-Ping Jin
• 金额: $ 32.43万
• 依托单位: NORTHSHORE UNIVERSITY HEALTHSYSTEM
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7239503
• 关键词: Actomyosin Adenosinetriphosphatase; Acute; Adult; Affect; Affinity; Alleles; Alternative Splicing; Amino Acid Substitution; Binding; Biochemical; Biological Assay; Biological Preservation; Calmodulin; Canis familiaris; Cardiac; Cardiac Muscle Contraction; Cardiac Myocytes; Cardiomyopathies; Cardiovascular Diseases; Cause of Death; Complex; Condition; Congenital Heart Defects; Country of Turkey; Cyclic AMP-Dependent Protein Kinases; Development; Dilated Cardiomyopathy; Embryo; Exons; Family; Figs - dietary; Financial compensation; Foundations; Functional disorder; Genes; Genetic Polymorphism; Hand; Heart; Heart failure; Heterogeneity; Human; Hypertrophy; Life Style; Link; Masks; Meleagris gallopavo; Microfilaments; Modeling; Molecular; Molecular Weight; Mus; Muscle; Muscle Cells; Muscle Contraction; Muscle function; Mutation; Myocardial; Myocardial Contraction; Myocardium; Myofibrils; Myopathy; Myosin ATPase; Myosin Light Chains; N-terminal; Natural Selections; Numbers; Pathogenesis; Performance; Perinatal; Phosphorylation; Physiological; Play; Population; Preparation; Prevention; Principal Investigator; Protein Isoforms; Protein Subunits; RNA Splicing; Rattus; Regulation; Role; Signaling Protein; Skeletal Muscle; Skin; Striated Muscles; Structure; Structure-Activity Relationship; System; Testing; Thin Filament; Time; Transgenic Mice; Transgenic Organisms; Tropomyosin; Troponin; Troponin C; Troponin I; Troponin T; Turkey bird; Upper arm; Variant; Work; base; cardiogenesis; genetic regulatory protein; in vitro Assay; in vivo; mouse model; novel; novel strategies; prevent; programs; response; sample fixation

DESCRIPTION (provided by applicant): Cardiac muscle contraction is regulated by Ca2+ binding to the troponin complex, which consists of 3 subunits: troponin C, troponin I and troponin T. This proposal investigates the role of abnormally spliced cardiac troponin T (cTnT) in the pathogenesis of dilated cardiomyopathy (DCM) and the compensation for this abnormal cTnT by a cardiac troponin I (cTnl) polymorphism. We previously discovered the presence of cTnT variants with abnormally spliced N-terminal regions in turkey and mammalian models of DCM. Since abnormal cTnT splicing also occurs in myopathic and failing human hearts, these cTnT variants may play a role in the pathogenesis and pathophysiology of DCM and heart failure. We hypothesize that the cTnT heterogeneity resulting from the presence of 2 or more functionally distinct cTnT variants in the normally uniform adult cardiac muscle desynchronizes contraction and decreases myocardial efficiency. We have developed transgenic mice expressing the DCM-related cTnT variants in their cardiac muscle for functional characterization. We will examine the effects of the abnormal cTnTs on the activity of actomyosin ATPase, the contractility of single myocytes and skinned muscle strips, the function of isolated working hearts, and the in vivo cardiac function of the mice. Increased binding affinity to cTnl is a primary abnormality of the DCM-related cTnTs. We recently found a novel polymorphism of cTnl (Arg111Cys) in wild turkey hearts. Arg-m is conserved as Arg or Lys in all cardiac and skeletal muscle Tnls, and sits in a coiled-coil interface between Tnl and TnT. The Arg111Cys substitution in cTnl lowers its binding affinity for cTnT, which is potentially compensatory for DCM-related cTnT abnormalities. Therefore, the presence of the cTnl-Cysm allele in wild turkeys may prevent the onset of DCM and thus have a significant selection value. To investigate this hypothesis, we will biochemically and physiologically characterize the turkey cTnl-Cysm polymorphism in transgenic mice. We will then coexpress this cTnl polymorphism with the DCM cTnT in double-transgenic mice to examine its compensatory effects. Using these integrated physiological systems, this study will significantly contribute to our understanding of the structure-function relationships among the troponin subunits and lay a foundation for the prevention and treatment of cTnT cardiomyopathies.

描述（由申请人提供）：心肌收缩由Ca 2+与肌钙蛋白复合物结合来调节，肌钙蛋白复合物由3个亚基组成：肌钙蛋白C、肌钙蛋白I和肌钙蛋白T。本研究旨在探讨异常剪接的心肌肌钙蛋白T（cTnT）在扩张型心肌病（DCM）发病机制中的作用，以及心肌肌钙蛋白I（cTnI）多态性对这种异常cTnT的补偿作用。我们以前发现存在cTnT变异异常剪接的N-末端区域在火鸡和哺乳动物模型的DCM。由于异常cTnT剪接也发生在肌病和衰竭的人类心脏中，这些cTnT变体可能在DCM和心力衰竭的发病机制和病理生理学中发挥作用。我们假设，正常一致的成人心肌中存在2种或2种以上功能不同的cTnT变体导致cTnT异质性，从而使收缩失稳并降低心肌效率。我们已经开发了在其心肌中表达DCM相关cTnT变体的转基因小鼠，用于功能表征。我们将研究异常cTnTs对肌动球蛋白ATP酶活性、单个肌细胞和带皮肌条的收缩性、离体工作心脏的功能以及小鼠体内心功能的影响。与cTnI的结合亲和力增加是DCM相关cTnT的主要异常。我们最近在野生火鸡心脏中发现了cTnI（Arg 111 Cys）的一种新的多态性。Arg-m在所有心脏和骨骼肌Tnl中保守为Arg或Lys，并且位于Tnl和TnT之间的卷曲螺旋界面中。cTnI中的Arg 111 Cys取代降低了其与cTnT的结合亲和力，这可能是对DCM相关cTnT异常的补偿。因此，野生火鸡中cTnl-Cysm等位基因的存在可以防止DCM的发作，因此具有显著的选择价值。为了研究这一假设，我们将在转基因小鼠中对火鸡cTnl-Cysm多态性进行生物化学和生理学表征。然后，我们将在双转基因小鼠中共表达这种cTnI多态性与DCM cTnT，以检查其代偿作用。利用这些完整的生理学系统，本研究将有助于我们理解肌钙蛋白亚基之间的结构-功能关系，为cTnT心肌病的预防和治疗奠定基础。