Cytoskeletal-Based Survival Pathways in Myocardium

描述(申请人提供)：保护心肌细胞免于死亡是降低心肌梗死相关死亡率的最好方法。尽管描述了许多能够保护心肌细胞免受致命损伤的干预措施，但在临床领域应用这些干预措施的潜在希望仍然没有实现，部分原因是缺乏对心脏对应激反应的综合了解。一个尚不清楚的具体领域是，心肌应激是如何通过肌膜传递到单个心肌细胞水平的保护信号的。我们实验室的长期目标是在心肌细胞水平上更好地了解负责心肌保护信号的细胞和分子机制(S)。这项建议的目的是证明，通过细胞骨架途径的信号可以被激活，以提高心肌细胞在致命的缺血损伤中的存活。粘着斑激酶(FAK)已被公认为心脏和其他组织中细胞生存信号通路的关键介质。最近的数据表明，FAK、细胞骨架和其他亚细胞信号蛋白参与了一条完整的信号通路，这些信号蛋白可以被应激放大或刺激，特别是缺血/再灌注、热休克和/或膜受体刺激。这项提议将检验这样一种假设，即心肌应激，无论是直接还是通过受体激活，都会放大基于细胞骨架的信号级联，从而导致心肌细胞存活时间延长。该提案的具体目的将证明：1)FAK的激活在对细胞外心肌应激的反应中发挥核心作用；2)基于细胞骨架的途径的激活通过激活Akt而导致心脏保护；以及3)该途径的激活发生在完整的心脏中，并可能为许多已描述的心脏保护干预提供一条共同的途径。应激激活的特定细胞存活蛋白将在一系列综合实验中利用重组腺病毒、生化和培养心肌细胞的显微分析进行评估，并将在完整的心脏中使用隔离灌流的大鼠和小鼠缺血细胞死亡模型进行确认。对这一生存/适应途径的潜在机制(S)的表征将加深我们对不可逆转损伤的理解，并可能为急性心肌梗死的治疗带来新的和创新的临床策略。

DESCRIPTION (provided by applicant): Protecting myocytes from death is the best way to lower the mortality associated with myocardial infarction. Despite the description of many interventions capable of protecting myocytes from lethal injury, the potential promise of applying these interventions in the clinical arena has remained unfulfilled due in part to a lack of an integrative understanding of the heart's response to stress. One specific area that remains poorly understood is how myocardial stress is transduced across the sarcolemmal membrane into a protective signal at the level of the individual myocyte. The long term goal of our laboratory is to understand better the cellular and molecular mechanism(s) responsible for cardioprotective signaling at the level of the myocyte. The goal of this proposal is to demonstrate that signaling through a cytoskeletal based pathway can be activated to enhance myocyte survival against lethal ischemic injury. Focal adhesion kinase (FAK) has become recognized as a key mediator of cell survival signaling pathways in heart as well as other tissues. Recent data has demonstrated that an integrated signaling pathway exists involving FAK, the cytoskeleton, and other subcelluar signaling proteins that can be amplified or stimulated by stress; specifically ischemia/reperfusion, heat shock, and/or membrane receptor stimulation. This proposal will test the hypothesis that myocardial stress, either directly or through receptor activation, amplifies a cytoskeletal- based signaling cascade that results in prolonged myocyte survival. Specific aims of the proposal will demonstrate that: 1) activation of FAK plays a central role in the response to extracellular myocardial stress; 2) activation of the cytoskeletal-based pathway results in cardioprotection through activation of Akt; and 3) activation of the pathway occurs in intact hearts and may provide a common pathway for many described cardioprotective interventions. The specific cell survival proteins activated by stress will be evaluated in a series of integrated experiments utilizing recombinant adenoviruses, biochemical, and microscopic analysis of cultured cardiomyocytes, and will be confirmed in intact hearts using isolated perfused rat and mouse models of ischemic cell death. Characterization of the underlying mechanism(s) of this survival/adaptive pathway will enhance our understanding of irreversible injury and may lead to new and innovative clinical strategies in the therapy of acute myocardial infarction.