Role of Prolyl Hydroxylase Oxygen-Sensor in Cardioprotection

描述（由申请人提供）：允许细胞感知和响应[O2]的机制对于理解许多病理过程至关重要。最近，细胞[O2]感应机制被确定为[O2]依赖性脯氨酸羟化酶（PHD）家族。PI的新研究已经检测了使用乙基-3,4二羟基苯甲酸酯（EDHB）和二甲基氧基甘氨酸（DMOG）激活心肌细胞中PHD氧感应途径的后果，这两种小分子药物可以激活PHD氧感应途径。发现PHD通路的激活可诱导一氧化氮合酶-2和血红素加氧酶-1的水平。在分子水平上观察到这些变化的同时，心肌细胞中[O2]感应途径的激活赋予了一种对代谢抑制（Ml）应激具有显著抗性的表型。特别是，我们发现在PHD通路被激活的细胞中，线粒体功能在Ml期间受到保护，并且在Ml后恢复得更好。提出的工作的主要目标是确定博士通路激活后发生的变化，并了解这些变化如何赋予心脏保护并影响心脏细胞的生理机能。为此目的，将讨论一系列相互关联的具体目标。特异性目标1将测试PHD通路的激活是否指导心肌细胞生理变化与冬眠表型一致，并确定PHD通路下调的能量消耗过程。具体目标2是确定phd通路的激活如何在代谢损伤期间保护线粒体，并在代谢毒物或再氧化清除后促进线粒体恢复。具体目标3是建立hif依赖性或独立性的PHD反应，并确定新的非hif介导的PHD通路的作用。这些研究将提供关于心脏细胞对缺氧应激的特定分子反应的基本信息。这些研究对人类健康最直接的适用性在于，它们将首次表征一类有前途的新型药物的生物活性，这些药物可以激活内源性细胞保护机制。这些研究可能为药物的开发奠定基础，这些药物可以诱导对低氧水平或涉及血液流动不畅的疾病的保护。

DESCRIPTION (provided by applicant): The mechanisms that allow cells to sense and respond to [O2] are of fundamental importance in understanding a number of pathological processes. Recently the cellular [O2]-sensing mechanism has been identified as a family of [O2]-dependent prolyl hydroxylase enzymes (PHD). New studies by the PI have examined the consequences of activating the PHD oxygen-sensing pathway in cardiac myocytes using ethyl-3,4 dihydroxybenzoate (EDHB) and dimethyloxalylglycine (DMOG), small molecule agents that activate the PHD oxygen-sensing pathway. Activation of the PHD pathway is found to induce the levels of nitric oxide synthase-2 and heme oxygenase-1. Concurrent with these observed changes at the molecular level, a phenotype that is remarkably resistant to metabolic-inhibition (Ml) stress is conferred by the activation of the [O2]-sensing pathway in the cardiomyocyte. In particular, we find that mitochondrial function is protected during, and recovers better after Ml in cells where PHD pathway has been activated . The broad goals of the proposed work are to establish what changes occur as a result of the activation of the PHD-pathway, and to understand how these changes confer cardioprotection and influence the physiology of the heart cell. To these ends, a series of interrelated specific aims will be addressed. Specific Aim 1 will test if activation of the PHD pathway directs changes in cardiac cell physiology consistent with a hibernating phenotype and identify the energy consuming processes that are down regulated by the PHD-pathway. Specific Aim 2 is to determine how activation of the PHD-pathway protects the mitochondrion during a metabolic insult and promotes mitochondrial recovery upon washout of metabolic poisons or reoxygenation. Specific Aim 3 is to establish the HIF-dependence or-independence of PHD responses, and to identify novel non-HIF mediated actions of the PHD pathway. These studies will provide fundamental information regarding the specific molecular responses of the heart cell to hypoxic stress. The most direct applicability of these studies to human health lies in the fact that they will provide among the first characterization of the biological activity of a promising new class of drugs that can activate endogenous cellular protective mechanisms. These studies may lay the foundation for the development of Pharmaceuticals that induce protection against low oxygen levels or diseases involving poor blood flow.