Prolyl hydroxylase oxygen sensor in Heart

描述（由申请人提供） 允许细胞感知和响应氧气（O2）的机制对于理解环境因素如何影响无数的生理，病理和发育过程至关重要。 最近，细胞的氧传感器/转导机制已被确定为一个家庭的氧依赖性脯氨酰羟化酶（PHD）。 在缺氧条件下，这些酶的羟化酶活性受到抑制。 缺氧诱导因子-1 α羟基化失败导致其积累。 心血管系统对O2表现出极高的敏感性，具有急性和慢性反应的特征。 因此，候选人建议使用心脏细胞作为模型系统来探索受这种O2传感途径影响的特定机制。 候选人的新数据表明，PHD氧传感器可能在心脏的病理生理学中发挥重要作用。 PHD的特异性抑制剂激活细胞缺氧反应，并导致诱导两种应激反应蛋白：一氧化氮合酶-2（NOS-2）和血红素加氧酶-1（HO-1）。 这个建议的总体目标是开始探索PHD通路激活的后果及其在细胞对缺氧应激反应中的作用的性质。 具体目标1的目的是验证PHD抑制剂作为模型药物的用途。 新生肌细胞培养物将用于检查慢性PHD途径激活，以评价PHD抑制剂是否重现了对慢性缺氧的细胞反应。 特异性目的2利用了PHD途径激活高度诱导NOS-2蛋白表达的发现。 本研究的目的是了解PHD抑制剂如何导致NOS-2诱导。 NOS-2表达将在转录水平上用启动子分析进行评价。 这些研究也将探讨NOS-2在mRNA水平上的可能调控。 心脏对缺氧最显著的急性反应是收缩力的下调。具体目标3的目标是严格检查PHD氧传感器在介导缺血或缺氧损伤引起的急性收缩功能障碍中发挥作用的概念。

DESCRIPTION (provided by applicant) The mechanisms that allow cells to sense and respond to oxygen (O2) are of fundamental importance in understanding how environmental factors impact upon a myriad of physiological, pathological, and developmental processes. Recently the cellular O2-sensor/transducing mechanism has been identified as a family of O2-dependent prolyl hydroxylase enzymes (PHD). In hypoxic conditions the hydroxylase activity of these enzymes are inhibited. The failure to hydroxylate hypoxia-inducible factor-l alpha leads to its accumulation. The cardiovascular system displays exquisite sensitivity to O2 with a characteristic constellation of both acute and chronic responses. Thus, the candidate proposes using the heart cell as a model system to explore the specific mechanisms that are affected by this O2-sensing pathway. New data by the candidate suggests that the PHD oxygen sensor may play a large role in the pathophysiology of the heart. Specific inhibitors of PHD activate the cellular hypoxic response, and lead to induction of two stress-response proteins; nitric oxide synthase-2 (NOS-2) and heme oxygenase-1 (HO-l). The overall goal of this proposal is to begin to explore consequences of the PHD-pathway activation and the nature of its role in the cellular response to hypoxic stress. The goal of Specific Aim 1 is to validate the use of PHD inhibitors as model agents. Neonatal myocyte cultures will be used to examine chronic PHD-pathway activation in order to evaluate if cellular responses to chronic hypoxia are recapitulated by PHD inhibitors. Specific Aim 2 capitalizes on the finding that NOS-2 protein expression is highly induced by PHD-pathway activation. The goal of this aim is to understand how PHD inhibitors lead to NOS-2 induction. NOS-2 expression will be evaluated at the transcriptional level with promoter analysis. Possible regulation of NOS-2 at the mRNA level will also be addressed by these studies. The most prominent acute response of the heart to hypoxia is a down regulation of contractility. The goal of Specific Aim 3 is to critically examine the notion that the PHD oxygen sensor plays a role in mediating the acute contractile dysfunction that is seen with ischemic or hypoxic insult.