Adenosine A2 receptor activation--mitochondrial death

描述(申请人提供)：最近的大量研究表明，再灌注时线粒体死亡途径与坏死和细胞凋亡有关。因此，防止线粒体死亡途径是再灌流时成功的心脏保护的先决条件。虽然在再灌流时激活腺苷A2受体对心脏有保护作用，但其机制仍不清楚。本研究的目的是确定A2受体激活对线粒体死亡途径的影响，并阐明A2受体激活作用下的信号机制。我们假设NECA在再灌流时对A2受体激活的刺激通过涉及eNOS、NO、PKG、锌和GSK-3的信号级联来阻断线粒体死亡途径。我们将使用细胞生物学、分子生物学、生理学、药理学和基因打靶等多种技术来检验这些假说。目的1通过测定线粒体功能、心肌梗死面积和细胞凋亡指数，确定再灌流时A2受体激活对线粒体死亡途径的影响。目的2将通过确定PKA、酪氨酸激酶和HSP90在eNOS激活中的作用来确定A2受体激活产生NO的机制。目的3确定PKG在A2受体激活保护作用中的作用。我们将通过过表达或敲除PKG基因来确定PKG的作用。目的4将确定导致A2受体激活对线粒体死亡途径的预防作用的PKG激活的下游靶点。为了达到这个目标，我们将描述细胞内游离锌、线粒体KATP通道和GSK-3的作用。这一建议的成功实施将对A2受体激活对缺血/再灌注损伤的保护作用的信号机制产生重要的新见解，并对急性心肌梗死患者的治疗具有重要的临床意义。

DESCRIPTION (provided by applicant): A large number of recent studies have associated a mitochondrial death pathway at reperfusion with both necrosis and apoptosis. Preventing the mitochondrial death pathway, therefore, is a prerequisite for successful cardioprotection at reperfusion. Although adenosine A2 receptor activation at reperfusion has been proposed to protect the heart, its mechanisms are still not clear. The objective of this proposal is to determine the effects of A2 receptor activation on the mitochondrial death pathway and to elucidate the signaling mechanisms underling the effects of A2 receptor activation. We hypothesize that stimulation of A2 receptor activation by NECA at reperfusion interdicts the mitochondrial death pathway through a signal cascade involving eNOS, NO, PKG, zinc, and GSK-3. We will test these hypotheses by using diverse techniques of cell biology, molecular biology, physiology, pharmacology, and gene targeting. Aim 1 will determine the effects of A2 receptor activation at reperfusion on the mitochondrial death pathway by measuring mitochondrial function, infarct size, and indexes of apoptosis. Aim 2 will determine the mechanisms by which A2 receptor activation produces NO by defining the roles of PKA, tyrosine kinase, and HSP90 in activation of eNOS. Aim 3 will determine the role of PKG in the protective action of A2 receptor activation. We will define the role of PKG by overexpressing or knocking out the PKG gene. Aim 4 will ascertain the downstream targets of PKG activation that lead to the preventive effects of A2 receptor activation on the mitochondrial death pathway. Towards this goal we will characterize the roles of intracellular free zinc, mitochondrial KATP channels, and GSK-3. The successful execution of this proposal should produce important new insights into the signaling mechanisms underlying the protective effects of A2 receptor activation at reperfusion against ischemia/reperfusion injury, and have great clinical significance for treating patients with acute myocardial infarction.