Metabolic Mechanisms of Cardiac Injury and Protection

描述（由申请人提供）：心肌中基本细胞保护途径的鉴定是一个难以捉摸的挑战。虽然缺血预处理可能是已知的最有效的实验性心脏保护策略，但其发现的临床应用很少。基于缺血预处理过程中发生短暂代谢改变的前提，PI提出了一种新的假设，其中代谢信号的激活发挥保护作用。新出现的证据表明，一种特定的丝氨酸/苏氨酸翻译后修饰，β-O-连接的N-乙酰葡糖胺（O-GlcNAc）的水平的全球增加，保护细胞系免受损伤。在这里，PI将试图建立这种修饰作为一种新的心脏存活信号，并阐明其在心肌缺血再灌注损伤的潜在参与。该提案的总体结构旨在回答以下问题：在缺血再灌注和预处理期间，O-GlcNAc水平发生了什么变化？O-GlcNAc信号是否足以保护心脏？这个过程的目标是什么？这种潜在的保护途径是否会导致心脏功能的长期改善？在特定目标I（SA I）中，申请方将确定心肌缺血-再灌注期间和缺血预处理后O-GlcNAc水平的时间变化。使用补充药理学、腺病毒基因转移和RNA干扰介导的翻译沉默，PI将评价O-GlcNAc水平的增加是否减轻体内缺血或体外缺氧-复氧（SA II）后的心脏损伤。接下来，申请人将使用暴露于缺氧-复氧和体内心肌缺血-再灌注（SA III）的分离的肌细胞来表征O-GlcNAc介导的保护的下游靶标，即在线粒体中（例如KATP）。最后，PI将确定急性O-GlcNAc介导的保护是否改善心肌梗死后的体内长期心脏功能（SA IV）。从这些创新性研究中获得的数据可能会在缺血后心脏损伤和保护机制方面建立一个新的范式。在这个项目中可能的发现将允许开发新的策略来对抗患者的急性心肌梗死。概述：申请人将重点关注一个知之甚少的代谢途径，以评估心脏病发作期间的损伤机制。从这个建议中收集的信息可能有助于治疗心脏病。

DESCRIPTION (provided by applicant): Identification of fundamentally cytoprotective pathways in the myocardium lingers as an elusive challenge. Although ischemic preconditioning may be the most powerful experimental cardioprotective strategy known, little clinical application has resulted from its discovery. Based on the premise that transient metabolic alterations occur during ischemic preconditioning, the PI has developed a novel hypothesis wherein activation of a metabolic signal exerts protective effects. Emerging evidence indicates that global increases in levels of a specific serine/threonine post-translational modification, beta-O-linked N-acetylglucosamine (O-GlcNAc), protects cell lines against injury. Here, the PI will attempt to establish this modification as a novel cardiac survival signal and elucidate its potential involvement in myocardial ischemia-reperfusion injury. The general structure of this proposal is designed to answer the questions: What happens to O-GlcNAc levels during ischemia-reperfusion and preconditioning? Is the O-GlcNAc signal sufficient for cardioprotection? What are the target(s) in this process? Does this potentially protective pathway result in chronic improvement in cardiac function? In Specific Aim I (SA I), the applicant will identify temporal changes in O-GlcNAc levels during myocardial ischemia-reperfusion and following ischemic preconditioning. Using complementary pharmacology, adenoviral gene transfer, and RNA interference-mediated translational silencing, the PI will evaluate whether augmentation of O-GlcNAc levels attenuates cardiac injury following in vivo ischemia or in vitro hypoxia-reoxygenation (SA II). Next, the applicant will characterize the downstream targets, namely in the mitochondria (e.g. KATP), of O-GlcNAc-mediated protection using isolated myocytes exposed to hypoxia-reoxygenation and in vivo myocardial ischemia-reperfusion (SA III). Lastly, the PI will ascertain whether acute O-GlcNAc-mediated protection improves long-term cardiac function in vivo following myocardial infarction (SA IV). Data garnered from such innovative studies may establish a novel paradigm in the mechanism of post-ischemic cardiac injury and protection. Possible findings during this project will allow the development of new strategies to combat acute myocardial infarction in patients. LAY SUMMARY: The applicant will focus on a poorly understood metabolic pathway to evaluate the mechanisms of injury during a heart attack. Information gathered from this proposal may help treat heart disease.