Regulation of Contractility During Ischemia-Reperfusion

缺血再灌注过程中收缩力的调节

• 批准号: 7093213
• 负责人: OZGUR OGUT
• 金额: $ 29.6万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2011-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7093213
• 关键词: actins; affinity chromatography; cardiac myocytes; cytoskeletal proteins; gel electrophoresis; heart contraction; immunoprecipitation; ischemia; laboratory rat; molecular assembly /self assembly; myocardium disorder; posttranslational modifications; protein protein interaction; proteolysis; reperfusion; tropomyosin; western blottings

DESCRIPTION (provided by applicant): Myocardial infarction is prevalent with -1 million patients diagnosed each year. To better understand the cellular conditions leading to cardiomyocyte damage and death, experimental models have mimicked the ischemia - reperfusion (I-R) experienced by the myocardium. The decrease in ATP with I-R is often considered the driving force behind the contractility decline. However, recent research suggests that changes intrinsic to the contractile filaments, such as protein proteolysis or redox-dependent protein modifications, also influence contractility during I-R. The preliminary data in this application indicate that a decline in cardiac muscle contractility occurs with 30' of ischemia and is largely reversed by 60' of reperfusion. The reversible decline in contractility was independent of ATP availability, suggesting that intrinsic changes to the contractile filaments best described the decline. However, this timeframe is insufficient for protein proteolysis during ischemia to be rescued by protein synthesis and re-assembly during reperfusion. Therefore, these changes in contractility may reflect reversible, covalent modifications to proteins of the contractile filaments rather than their proteolysis. Consistent with this hypothesis, preliminary data demonstrate that a reversible modification of actin occurs during I-R, affecting it's interaction with tropomyosin. Therefore, this grant application aims to investigate fibre contractility during I-R, and characterize the reversible modifications to proteins of the contractile filaments that underlie the changes in contractility. The application will test the hypothesis that ischemia-reperfusion results in reversible, covalent modifications to proteins of the cardiac muscle thin filament, consequently limiting contractility through changes in the association of thin filament regulatory proteins. This hypothesis will be examined by: i) determining the effect of I-R on the contractility of cardiac muscle fibres; ii) characterizing the I-R dependent modification of actin, and determining if I-R results in covalent modifications to other thin filament proteins; iii) determining the effect of modification of actin on thin filament assembly as well as the actin activated myosin ATPase. These findings will provide novel insight into the nature of the contractile deficit during I-R, with emphasis on the state of the cardiac muscle thin filament proteins and their effect on contractility.

描述（由申请人提供）：心肌梗死普遍存在，每年诊断出100万例患者。为了更好地了解导致心肌细胞损伤和死亡的细胞条件，实验模型模拟了心肌缺血再灌注（I-R）过程。ATP随I-R的减少通常被认为是收缩力下降背后的驱动力。然而，最近的研究表明，收缩细丝固有的变化，如蛋白质蛋白水解或氧化还原依赖的蛋白质修饰，也会影响I-R期间的收缩性。本应用的初步数据表明心肌收缩力的下降发生在缺血30‘时，在再灌注60’时基本逆转。收缩性的可逆下降与ATP的可用性无关，表明收缩丝的内在变化最好地描述了收缩性的下降。然而，这个时间框架不足以使缺血期间的蛋白质水解被再灌注期间的蛋白质合成和重新组装所挽救。因此，这些收缩性的变化可能反映了可收缩细丝对蛋白质的可逆共价修饰，而不是它们的蛋白质水解。与这一假设相一致，初步数据表明，肌动蛋白在I-R过程中发生可逆修饰，影响其与原肌球蛋白的相互作用。因此，这项拨款申请旨在研究I-R期间纤维的收缩性，并表征收缩细丝对蛋白质的可逆修饰，这些修饰是收缩性变化的基础。该应用程序将验证缺血再灌注导致心肌细丝蛋白可逆共价修饰的假设，从而通过改变细丝调节蛋白的关联来限制收缩性。这一假设将通过以下方式加以检验：i)确定i - r对心肌纤维收缩力的影响；ii)表征肌动蛋白的I-R依赖性修饰，并确定I-R是否导致对其他细丝蛋白的共价修饰；iii)确定肌动蛋白修饰对细丝组装的影响以及肌动蛋白激活的肌球蛋白atp酶。这些发现将为I-R期间收缩缺陷的本质提供新的见解，重点是心肌细丝蛋白的状态及其对收缩性的影响。