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]的机制在理解许多病理过程中至关重要。最近，细胞内的[O2]感知机制被确定为一类依赖于[O2]的Pro羟基酶家族(PHD)。PI的新研究检测了使用3，4二羟基苯甲酸乙酯(EDHB)和二羟甲基甘氨酸(DMOG)激活PHD氧敏感途径的后果，这两种小分子药物激活了PHD氧敏感途径。PHD途径的激活被发现诱导一氧化氮合酶-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，心肌细胞中的[O2]感觉通路的激活赋予了一种显著抵抗代谢抑制(ML)应激的表型。特别是，我们发现在PHD途径被激活的细胞中，线粒体功能在ML期间受到保护，并且恢复得更好。这项拟议工作的主要目标是确定由于PHD途径的激活而发生的变化，并了解这些变化如何提供心脏保护并影响心脏细胞的生理。为此，将提出一系列相互关联的具体目标。特殊目的1将测试PHD途径的激活是否引导与冬眠表型一致的心肌细胞生理变化，并确定PHD途径下调的能量消耗过程。具体目的2是确定PHD途径的激活如何在代谢损伤时保护线粒体，并在代谢毒物被清除或复氧后促进线粒体恢复。具体目的3是建立PHD反应的HIF依赖或非依赖关系，并确定PHD途径的新的非HIF介导的作用。这些研究将提供有关心脏细胞对低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，它们将首先表征一类有希望的新药物的生物活性，这些药物可以激活内源性细胞保护机制。这些研究可能为开发对低氧水平或涉及血液流动不良的疾病具有保护作用的药物奠定基础。

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.