Role of protein hydoxylation in cellular response to hypoxia 67493

细胞如何“感知”环境中氧气的变化一直是生物学的核心问题。细胞环境中氧气的增加（高氧）或减少（缺氧）对细胞施加“压力”，细胞必须对此作出反应。细胞环境中对氧浓度变化的适应涉及基因和蛋白质表达的启动。这些过程的控制机制依赖于蛋白质结构和功能的氧依赖性修饰。由NSERC发现基金支持的拟议研究将在两个一般领域取得进展。第一个将在培养的哺乳动物细胞中发现受氧依赖的翻译后修饰的新蛋白质。二是进一步表征这些蛋白在氧胁迫下细胞存活中的作用。重点将放在适应低氧条件上。所有生物体都或多或少地遇到环境氧的变化。在人类中，适应高海拔和缺血（器官和组织的血液流动停止，如心脏骤停、中风或器官移植）需要对缺氧作出反应的能力。拟议的研究将集中在一种特定的氧依赖的蛋白质修饰称为羟基化。羟基化作用是由被称为羟化酶的特定酶进行的。氧的去除可以防止蛋白质羟基化，并可以稳定受到这种修饰的蛋白质。这类蛋白质在缺氧条件下可能具有增强的功能（或仅具有功能）。蛋白质组学方法已被用来揭示新的蛋白底物的羟化酶。在体内和体外研究中，鉴定出的蛋白质将被表征为缺氧下功能的改变。新的羟基化蛋白对缺氧细胞整体存活的作用将通过基因敲低来评估。结果将最终有助于了解生物体适应低氧条件的机制。

How cells "sense" a change in ambient oxygen has long been a central question in biology. Increases (hyperoxia) or decreases (hypoxia) of oxygen in the cellular milieu impose a "stress" upon cells to which they must respond. Adaptation to changes in oxygen concentration in a cell's environment involves the initiation of gene and protein expression. The mechanism of control of these processes is dependent upon oxygen-dependent modification of protein structure and function. The proposed research supported by this NSERC Discovery Grant will lead to progress in two general areas. The first will uncover novel proteins in cultured mammalian cells that are subject to oxygen-dependent posttranslational modification. The second will be to further characterize the role of these proteins in cellular survival of oxygen stress. The focus will be on adaptation to hypoxic conditions. All organisms encounter changes in ambient oxygen to a greater or lesser extent. In humans, adaptation to high altitudes and ischemia (cessation of blood flow to organs and tissues, such as during cardiac arrest, stroke or organ transplant) requires the ability to respond to hypoxia.   The proposed research will focus on a specific oxygen-dependent modification of proteins known as hydroxylation. Hydroxylation is carried out by specific enzymes known as hydroxylases. The removal of oxygen prevents protein hydroxylation and can stabilize proteins subject to this modification. Such proteins may have enhanced function (or may only function) under hypoxic conditions. A proteomic approach has been utilized to reveal new protein substrates of hydroxylases. Identified proteins will be characterized for altered function under hypoxia with both in vivo and in vitro studies. The role of novel hydroxylated proteins to the overall survival of cells to hypoxia will be assessed by gene knockdown. Results will ultimately contribute to an understanding of the mechanisms by which organisms adapt to low oxygen conditions.