Regulation and Maintenance of Cardiac Muscle Sarcomere Integrity

心肌肌节完整性的调节和维持

基本信息

批准号：
7988075
负责人：
CHEE CHEW LIM
金额：
$ 36.27万
依托单位：
VANDERBILT UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-05 至 2015-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7988075
关键词：
3&apos Untranslated Regions Actins Affect Amines Antioxidants Attention Calpain Cardiac Cardiac Myocytes Cardiomyopathies Cell Nucleus Complex Data Disease Equilibrium Event Excision Fluorescent in Situ Hybridization Genes Genetic Transcription Goals Half-Life Health Heart Heart Hypertrophy Heart failure Heterogeneity In Vitro Individual Kinetics Lead Macromolecular Complexes Maintenance Mediating Messenger RNA Methods Microfilaments Modeling Molecular Molecular Biology Molecular Weight Mus Muscle Cells Myocardium Myosin ATPase Oxidative Stress Oxis Pathway interactions Physiological Process Protease Inhibitor Protein Biosynthesis Proteins Reactive Oxygen Species Recycling Regulation Regulatory Element Reporter Role Sarcomeres Signaling Protein Structure System Testing Transgenic Organisms Translations Ubiquitin Untranslated Regions Work base calpastatin connectin cost design genetic regulatory protein in vivo insight multicatalytic endopeptidase complex novel therapeutic intervention oxidative damage promoter protein degradation public health relevance titin 1 titin 2

项目摘要

DESCRIPTION (provided by applicant): The cardiac sarcomere is a complex and highly ordered ensemble of contractile and regulatory proteins designed to generate force. To maintain functional sarcomeres, precise turnover of proteins is required that balances new protein synthesis and incorporation into the sarcomere with removal and degradation of worn out or damaged proteins. Given the heterogeneity in protein turnover rates, the mechanisms by which independent turnover of the individual sarcomere components occurs while maintaining the functional integrity of the sarcomere structure, is not well understood. Several studies have shown that a number of myofilament proteins, including actin and myosin, are in kinetic equilibrium with a cytoplasmic precursor pool, suggesting continual replacement of worn out myofilament proteins for their precursors into an otherwise intact sarcomere. As the size of the protein increases, however, several problems arise that make simple sarcomere protein exchange improbable. For one, the maintenance of a precursor pool of high molecular weight proteins comes at an increasing energetic cost to the myocyte. Another problem is that unlike smaller myofilament proteins that are continually recycled in the existing sarcomere, turnover of myofibrillar macromolecular complexes likely requires either partial or complete disassembly of the sarcomere. These considerations have focused our attention on the molecular events regulating the turnover of the giant myofilament protein titin. Titin is an integral part of the sarcomere complex, serving as (1) a molecular template around which the myosins and other structural and signaling proteins assemble, and (2) a molecular spring to impart myofibrillar stiffness to the heart. We therefore postulate that the degradation of titin will trigger local disassembly of the sarcomere. Based on preliminary data, we propose that oxidative damage to titin triggers sequential degradation by the calpains and ubiquitin-proteasome system. We propose that sarcomere mechanosensors are activated during the process of titin degradation, and translocate to the nucleus to activate titin gene transcription. We propose that titin mRNA is targeted to the sarcomere and that localized titin synthesis occurs with concurrent reassembly of the sarcomere. We finally propose that cardiac hypertrophy modulates titin transcription and translation pathways leading to net sarcomere addition. The proposed experimental aims will allow us to evaluate and refine this model, and advance our understanding of the complex physiological and temporal aspects of myofilament sarcomere turnover. PUBLIC HEALTH RELEVANCE: The cardiac sarcomere is the basic contractile unit of the heart and is composed of an ensemble of myofilament and regulatory proteins designed to generate force. It is generally assumed that maintenance of functioning sarcomeres requires precise control of synthesis, assembly, and degradation of myofilament proteins, however, the mechanisms that mediate turnover of large integrated myofilament proteins, such as titin, have not been looked at. Understanding the molecular mechanisms of titin protein turnover will provide insight into the regulatory processes of sarcomere maintenance, and may ultimately lead to novel therapeutic approaches for heart failure cardiomyopathies.

描述（由申请人提供）：心脏肌膜是一种复杂且高度有序的收缩和调节蛋白的合奏，旨在产生力。为了维持功能性肉瘤，要求蛋白质的精确周转率必须使新的蛋白质合成并掺入肌膜中，并将其去除和降解磨损或受损的蛋白质。鉴于蛋白质周转率的异质性，在保持肌节结构的功能完整性的同时，尚不清楚单个肌动成分独立周转的机制。几项研究表明，许多肌丝蛋白（包括肌动蛋白和肌球蛋白）与细胞质前体池保持在动力学平衡中，这表明持续替代了将其前体磨损的肌丝蛋白替换为原本完整的Saromere。然而，随着蛋白质的大小增加，出现了几个问题，使简单的肌节蛋白质交换不可能。首先，维持高分子量蛋白的前体池以越来越多的能量成本对心肌细胞产生。另一个问题是，与现有的肌动蛋白不断回收的较小的肌丝蛋白不同，肌原纤维大分子复合物的营业额可能需要部分或完全拆卸肉瘤。这些考虑因素将我们的注意力集中在调节巨型肌丝蛋白滴定周转的分子事件上。 Titin是肌节络合物不可或缺的一部分，它是（1）一个分子模板，肌动物以及其他结构和信号蛋白的组装，以及（2）分子弹簧，将肌原纤维刚度赋予心脏。因此，我们假设titin的降解将触发肌节的局部拆卸。基于初步数据，我们提出对TITIN的氧化损害会触发Calpains和ubiquitin-Proteasemome系统的顺序降解。我们提出，在Titin降解过程中激活了肉瘤的机械传感器，并转移到细胞核中以激活Titin基因转录。我们建议将钛mRNA靶向肌膜，并以同时重新组装肉皮发生局部质titin合成。我们最终提出，心脏肥大调节钛转录和翻译途径，从而导致Net Saromere添加。提出的实验目的将使我们能够评估和完善该模型，并促进我们对肌丝肌肌动肌周转的复杂生理和时间方面的理解。公共卫生相关性：心脏肌膜是心脏的基本收缩单位，由旨在产生力的肌丝和调节蛋白组成。通常认为，功能性肉瘤的维持需要精确控制肌丝蛋白的合成，组装和降解，但是，尚未研究介导大型综合肌丝蛋白（例如替汀）的周转的机制。了解钛蛋白更新的分子机制将提供对肌节维持的调节过程的见解，并最终导致心力衰竭心肌病的新型治疗方法。