Subcellular Regulation of Autophagic Flux in Cardiomyocytes and the Heart

描述（由申请人提供）：自噬是细胞质成分（包括细胞器）被双膜结构吞没并通过与溶酶体融合而被破坏的过程。这一生理过程是正常内务的一部分，是蛋白质循环利用的一种方式，也是对损伤的反应。当细胞凋亡被阻断时，它可以作为一种诱导细胞死亡的机制，但更有趣的是，它还可以通过一种未知的机制阻止细胞凋亡。自噬在心肌缺血再灌注、心肌肥厚和心力衰竭的反应中起重要作用。我们假设自噬是一个选择性而非非特异性的过程，在一种情况下，受损的线粒体可能是自噬的首选目标，而内质网、收缩元件或聚合体可能是其他情况下的选择性目标。我们建议通过使用局限于单个亚细胞室的自噬摄取报告细胞来测试这一点。我们将研究可能上调自噬的特定生理刺激，并利用这些报告来确定哪些条件会诱导个别细胞室的选择性靶向。由于与促进细胞存活相比，我们对导致细胞死亡的自噬过程的差异知之甚少，因此我们将研究自噬刺激和选择性自噬去除区室在决定细胞死亡中的作用。这些活动将1)为研究自噬途径提供急需的工具；2)确定自噬在缺血/再灌注、饥饿和细胞器损伤等条件下去除受损细胞成分的选择性能力；3)证明这些过程与心肌细胞存活之间的关系。自噬是细胞回收受损细胞器和细胞质成分的过程，在心肌梗死后的心脏保护中起着不可或缺的作用，并可能通过促进细胞存活来改变心力衰竭的发展。彻底了解自噬在心脏中的作用以及调节这一过程的复杂分子途径是很重要的，因为它可能导致开发治疗冠状动脉疾病和心力衰竭的新型治疗药物。

DESCRIPTION (provided by applicant): Autophagy is the process whereby cytoplasmic components, including organelles, are engulfed by a double membrane structure and targeted for destruction by fusion with a lysosome. This physiological process occurs as part of normal housekeeping, as a way to recycle proteins and as a response to injury. It can be used as a mechanism to induce cell death when apoptosis is blocked but more interestingly, also prevents apoptosis through an unknown mechanism. Autophagy plays an important role in the heart in response to myocardial ischemia and reperfusion, hypertrophy and heart failure. We hypothesize that autophagy is a selective rather than nonspecific process and that damaged mitochondria may be the preferred target for autophagy in one circumstance while endoplasmic reticulum, contractile elements or aggresomes may be selective targets in other settings. We propose to test this by using reporters of autophagic uptake that are restricted to a single subcellular compartment. We will investigate specific physiologic stimuli that may upregulate autophagy and use these reporters to determine which conditions induce selective targeting of individual compartments. Since relatively little is known about the differences in the autophagic processes leading to cell death compared to promoting cell survival, we will investigate autophagic stimuli and the roles of selective autophagic removal of compartments in determining cell death. These proposed activities will 1) provide much needed tools to study the autophagy pathway 2) determine the selective capacity of autophagy in removing damaged cellular components under conditons such as ischemia/reperfusion, starvation and organelle damage and 3) demonstrate the relationship between these processes and cardiomyocyte survival. Autophagy, the process by which cells recycle damaged organelles and cytoplasmic components, plays an integral role in cardioprotection following myocardial infarction and may alter the development of heart failure by promoting cell survival. It is important to thoroughly understand the role of autophagy in the heart and the complex molecular pathways that regulate this process as it may lead to the development of novel therapeutic agents for treatment of coronary artery disease and heart failure.