Control of Anoxia-Reoxygenation Responses by the O2-sensing Enzyme EGL-9 Pathway

描述(由申请人提供)：缺氧(缺氧)后复氧会在多种医疗条件下造成严重的有害影响，包括缺血再灌注损伤和心肌梗死。动物如何感知缺氧-复氧和防止组织损伤是基本的和尚未回答的问题。转录因子缺氧诱导因子(HIF)是抗缺氧复氧(A/R)损伤的关键细胞保护因子。线虫基因egl-9编码HIF-1的氧敏感的脯氨酸羟基酶，它的发现导致了一条进化上保守的维持途径的鉴定 从线虫到人类的有机体中的O2动态平衡。抑制哺乳动物HIF羟基酶同源物的EGL-9强烈保护心肌缺血和再灌注损伤。通过在氧气浓度变化的情况下进行自动行为跟踪，我发现了一种称为O2-on反应的运动性行为，并表明O2-on反应可以模拟哺乳动物组织对缺血再灌注损伤的关键方面的反应。EGL-9是O2-on反应所必需的，并介导低氧预适应对O2-on反应的抑制作用。从一系列的遗传筛选中，我发现Cysl-1是EGL-9的新调节因子，也是一种细胞色素P450酶，它能在EGL-9下游产生二十烷类信号分子来控制O2-On反应。我还分离了线虫突变体，它们定义了EGL-9/HIF-1途径的其他新的调节因子和靶标。该项目的总体目标是克隆由这些突变体定义的基因，并确定受EGL-9途径调控的A/R生物反应的新的保守调节因子，并确定潜在的分子和细胞机制。在这个项目的K99阶段，我将建立和表征线虫缺血再灌注损伤的行为和细胞模型。在这个项目的R00阶段，我将进一步确定A/R引起O2-ON反应的关键机制，并确定EGL-9途径的新的保守调节因子和靶点，该途径介导对A/R诱导的细胞损伤和行为反应的保护。使用结合分子、细胞和行为分析以及强大的基因筛选，我将系统地剖析遗传途径，并定义调节细胞和动物对A/R的反应的基本机制。在K99/R00提供的支持和培训机会的支持下，我计划扩大我目前的实验和智力技能，并发展与O2相关的生物学和疾病领域的专业知识。这对我领导一个独立而成功的研究实验室的职业目标至关重要。

DESCRIPTION (provided by applicant): Anoxia (lack of oxygen) followed by reoxygenation causes severe detrimental effects in a wide variety of medical conditions, including ischemic reperfusion injury and myocardial infarction. How animals sense anoxia- reoxygenation and prevent tissue injury are fundamental and unanswered issues. The transcription factor hypoxia inducible factor (HIF) is a key cell protector against anoxia-reoxygenation (A/R)-induced injury. The discovery of the C. elegans gene egl-9, which encodes an O2-sensing prolyl hydroxylase of HIF-1, has led to the identification of an evolutionarily conserved pathway central for maintaining O2 homeostasis in organisms from nematodes to humans. Inhibition of mammalian HIF hydroxylase homologs of EGL-9 strongly protects from myocardial ischemia and reperfusion injury. Using automated behavioral tracking under conditions of changing O2 concentrations, I discovered a locomotary behavior called the O2-ON response and have shown that the O2-ON response can model key aspects of mammalian tissue response to ischemia-reperfusion injury. EGL-9 is essential for the O2-ON response and mediates the effect of hypoxic preconditioning on the suppression of the O2-ON response. From a series of genetic screens, I discovered CYSL-1 as a new regulator of EGL-9 and a Cytochrome P450 enzyme that generates eicosanoid signaling molecules downstream of EGL-9 to control the O2-ON response. I also isolated C. elegans mutants that define additional novel regulators and targets of the EGL-9/HIF-1 pathway. The overall goal of this project is to clone the genes defined by these mutants and identify the novel conserved regulators of biological responses to A/R, which is modulated by the EGL-9 pathway, and determine the underlying molecular and cellular mechanisms. In the K99 phase of this project, I will establish and characterize C. elegans behavioral and cellular models for ischemia-reperfusion injury. In the R00 phase of this project, I will further determine the key mechanisms by which A/R causes the O2-ON response and identify novel conserved regulators and targets of the EGL-9 pathway, which mediates protection from A/R-induced cellular injury and behavioral response to A/R. Using combined molecular, cellular and behavioral analyses together with powerful genetic screens, I will systematically dissect the genetic pathways and define the fundamental mechanisms that regulate cellular and animal responses to A/R. With the support of and training opportunities provided by K99/R00, I plan to expand my current experimental and intellectual skills and develop expertise in areas of O2-related biology and diseases, which is vital to my career goal of directing an independent and successful research laboratory.