Proteolytic Regulation of Troponin T & Cardiac Function

肌钙蛋白 T 的蛋白水解调节

• 批准号: 8232243
• 负责人: Jian-Ping Jin
• 金额: $ 4.81万
• 依托单位: WAYNE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8232243
• 关键词: ATP phosphohydrolase; Actomyosin Adenosinetriphosphatase; Acute; Affect; Alternative Splicing; Animals; Binding; Binding Sites; Biochemical; Biochemistry; C-terminal; Calcium; Calmodulin; Calpain; Cardiac; Cardiac Muscle Contraction; Cardiac Myocytes; Cessation of life; Chronic; Complex; Congestive Heart Failure; Coronary heart disease; Development; Dose; Excision; Exercise; Family; Financial compensation; Foundations; Functional disorder; Future; Genes; Heart; Heart failure; Immunoglobulin Variable Region; Infarction; Injury; Ischemia; Knowledge; Lead; Learning; Life; Link; Mechanics; Metabolic; Microfilaments; Modeling; Modification; Molecular; Molecular Conformation; Motor; Mus; Muscle; Muscle Cells; Muscle Contraction; Myocardial; Myocardial Contraction; Myocardial Ischemia; Myocardial dysfunction; Myocardium; Myofibrils; Myosin ATPase; Myosin Light Chains; N-terminal; Nature; Outcome; Pathogenesis; Phase; Phenotype; Physiologic intraventricular pressure; Physiological; Plant Roots; Post-Translational Protein Processing; Post-Translational Regulation; Preparation; Prevention; Prevention approach; Production; Protein Binding; Protein Subunits; Proteins; Proteolysis; Pump; Rattus; Regulation; Regulation of Proteolysis; Reperfusion Injury; Reperfusion Therapy; Reporting; Research Project Grants; Role; Skin; Stress; Stretching; Striated Muscles; Structure; Structure-Activity Relationship; System; Testing; Thin Filament; Time; Transgenic Mice; Transgenic Organisms; Translating; Tropomyosin; Troponin; Troponin C; Troponin I; Troponin T; Variant; Ventricular; Work; base; cardiogenesis; clinical application; connectin; coping; functional loss; genetic regulatory protein; heart function; improved; in vivo; novel; postnatal; pressure; protein complex; public health relevance; receptor; reconstitution; research study; response; therapeutic development

DESCRIPTION (provided by applicant): Cardiac muscle contraction is regulated by Ca2+ through the troponin complex that consists of three protein subunits: troponin C, troponin I, and troponin T (TnT). This research project investigates the role of a novel posttranslational modification of cardiac TnT (cTnT) in myocardial adaptation to energetic crisis. We recently reported a restricted N-terminal proteolysis of cTnT in myocardial ischemia-reperfusion (Zhang et al., Biochemistry 45:11681-94, 2006) and pressure overload (Feng et al., J. Physiol. 586:3537-50, 2008). This modification selectively removes the N-terminal variable region of cTnT but keeps the conserved middle and C-terminal regions intact. Initial studies in transgenic mouse hearts showed that the N-terminal truncated cTnT (cTnT-ND) remains functional in the myofilaments and alters myocardial contractility. This finding has lead to a hypothesis that the proteolytic removal of the N-terminal variable region of cTnT produces a functional state in cardiac muscle thin filaments as acute adaptation to energetic crisis. To test this hypothesis and understand the physiological and pathophysiological significance of cTnT- ND, three Specific Aims are proposed in this research project: Aim I will characterize the effects of the selective deletion of the N-terminal variable region on the function of cTnT. We will examine the interactions of cTnT-ND with other thin filament regulatory proteins and its functional impacts on the Ca2+ activation of myofibril ATPase and the contractility of cardiac muscle. Aim II will study the role of N-terminal truncated cTnT in compensating cardiac function and providing myocardial protection against ischemia-reperfusion injury. The acute and chronic effects of cTnT-ND on heart function and its role in overcoming energetic crisis will be investigated in ex vivo working hearts and in vivo. Aim III will investigate the role of mechanical stretch of the cardiac muscle in inducing the restricted proteolytic cleavage of cTnT N-terminal segment in order to understand the mechanisms that regulates this posttranslational regulation. Using integrated experimental systems, this study will gain new knowledge for the structure-function relationships of TnT and lay a foundation for future development of new treatment of ischemic heart disease and heart failure. PUBLIC HEALTH RELEVANCE: Myocardial contraction is essential for heart function. The contraction of cardiac muscle is regulated by calcium via the function of troponin, a protein complex in muscle cells. Cardiac troponin T (cTnT) is a subunit of the troponin complex in cardiac muscle. In a recent study, we found a restricted cleavage of cTnT in stress conditions such as acute myocardial ischemia. This modification of cTnT selectively removes the N-terminal variable region and keeps the remaining conserved structure in the myofibrils with functional consequences. Initial studies of transgenic mouse hearts showed that the N-terminal truncated cTnT (cTnT- ND) has a beneficial effect on the pumping efficiency of the heart. This observation lead us to propose a novel hypothesis that the removal of the N-terminal segment of cTnT is a rapid posttranslational mechanism to produce a transient functional state in the cardiac muscle for coping with energetic crisis. In the present study, we will characterize the physiological and pathophysiological functions of cTnT-ND. We shall examine the effects of restricted N-terminal truncation on the biochemical function of cTnT, the calcium activation of myofibril motors and the contractility of cardiac muscle. The potential role of cTnT-ND in reducing myocardial dysfunction and protecting the cardiac muscle during ischemia will be studied in isolated working hearts and in living animals. The mechanisms for mechanical stretch to induce the production of cTnT-ND will also be investigated. These experiments will provide new information for understanding the role of cTnT-ND in myocardial adaptation to energetic crisis. Using integrated physiological systems, this experimental research will also contribute key information for the structure-function relationship of TnT and lay a foundation for future development of new treatment of ischemic heart diseases and heart failure.

描述（由申请人提供）： 心肌收缩由Ca2+通过肌钙蛋白复合物调节，由三种蛋白质亚基组成：肌钙蛋白C，肌钙蛋白I和肌钙蛋白T（TNT）。该研究项目研究了心肌TNT（CTNT）在心肌适应充满活力危机中的新型翻译后修饰的作用。 我们最近报道了CTNT在心肌缺血 - 重新灌注中的N端蛋白水解受限（Zhang等，生物化学45：11681-94，2006）和压力超负荷（Feng等人，J。Physiol。586：3537-50-50，586：3537-50，，， 2008）。这种修饰选择性地去除了CTNT的N末端变量区域，但保持保守的中间和C末端区域完整。在转基因小鼠心脏中的初步研究表明，N末端截短的CTNT（CTNT-ND）在肌膜中保持功能，并改变心肌收缩力。这一发现导致了一个假设，即CTNT的N末端变量区域的蛋白水解去除会在心脏肌肉薄细丝中产生功能状态，因为急性适应能量危机。 为了检验这一假设并了解CTNT的生理和病理生理学意义，在本研究项目中提出了三个具体目的：目的我将表征N端变量区域选择性缺失对CTNT功能的影响。我们将检查CTNT-ND与其他薄丝调节蛋白的相互作用及其对肌纤维ATPase Ca2+激活的功能影响和心脏肌肉的收缩力。 AIM II将研究N末端截断CTNT在补偿心脏功能方面的作用，并提供针对缺血再灌注损伤的心肌保护。 CTNT-ND对心脏功能的急性和慢性作用将在离体工作心脏和体内研究。 AIM III将研究心肌的机械拉伸在诱导CTNT N末端段的蛋白水解裂解中的作用，以了解调节这种翻译后调节的机制。 使用综合实验系统，本研究将获得TNT结构功能关系的新知识，并为未来的缺血性心脏病和心力衰竭的新治疗奠定了基础。 公共卫生相关性： 心肌收缩对于心脏功能至关重要。心肌的收缩通过钙通过肌钙蛋白的功能（肌肉细胞中的蛋白质复合物）的功能调节。心脏肌钙蛋白T（CTNT）是心肌中肌钙蛋白复合物的亚基。在最近的一项研究中，我们发现CTNT在急性心肌缺血等应力条件下的裂解受到限制。 CTNT的这种修饰有选择地去除N末端变量区域，并在肌原纤维中保持剩余的保守结构，并具有功能后果。转基因小鼠心脏的初步研究表明，N末端截短的CTNT（CTNT）对心脏的抽水效率具有有益的作用。 这一观察结果使我们提出了一个新的假设，即去除CTNT的N末端段是一种快速的翻译后机制，可以在心脏肌肉中产生短暂的功能状态以应对能量危机。在本研究中，我们将表征CTNT-ND的生理和病理生理功能。我们将研究受限的N末端截断对CTNT的生化功能，肌膜电动机的钙激活和心脏肌肉收缩力的影响。 CTNT-ND在减少心肌功能障碍和保护缺血期间的心肌肌肉中的潜在作用将在孤立的工作心脏和活体动物中进行研究。还将研究诱导CTNT-ND产生的机械拉伸机制。 这些实验将提供新的信息，以了解CTNT-ND在心肌适应充满活力危机中的作用。使用综合生理系统，这项实验研究还将为TNT的结构功能关系提供关键信息，并为未来的缺血性心脏病和心力衰竭的新治疗奠定了基础。