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）后再给氧会对多种医学疾病（包括缺血性再灌注损伤和心肌梗死）造成严重的有害影响。动物如何感知缺氧-复氧并防止组织损伤是一个基本而未解决的问题。转录因子缺氧诱导因子（HIF）是一种重要的细胞保护因子，可保护细胞免受缺氧-复氧（A/R）损伤。C. elegans基因egl-9编码HIF-1的O2敏感脯氨酰羟化酶，已经鉴定出一种进化上保守的途径， 从线虫到人类的有机体中的O2稳态。EGL-9的哺乳动物HIF羟化酶同源物的抑制强烈地保护免于心肌缺血和再灌注损伤。在改变O2浓度的条件下使用自动行为跟踪，我发现了一种称为O2-ON反应的非线性行为，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反应的关键方面。EGL-9是O2-ON反应所必需的，并介导低氧预处理对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的一种新的调节剂，也是一种细胞色素P450酶，在EGL-9下游产生类花生酸信号分子，以控制O2-ON反应。我也分离出了C。elegans突变体，定义了EGL-9/HIF-1途径的其他新的调节因子和靶点。该项目的总体目标是克隆这些突变体定义的基因，并确定由EGL-9途径调节的A/R生物反应的新型保守调节因子，并确定潜在的分子和细胞机制。在本项目的K99阶段，我将建立和表征C。elegans缺血再灌注损伤的行为和细胞模型。在该项目的R 00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通路的新保守调节因子和靶点，EGL-9通路介导对A/R诱导的细胞损伤和对A/R的行为反应的保护。结合分子，细胞和行为分析以及强大的遗传筛选，我将系统地剖析遗传途径，并定义调节细胞和动物对A/R反应的基本机制。通过K99/R 00提供的支持和培训机会，我计划扩大我目前的实验和智力技能，并在O2相关生物学和疾病领域发展专业知识，这对我指导独立和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.