MODULATION OF AP ENDONUCLEASE BY AGING/OXIDATIVE STRESS

内源性和外源性活性氧（ROS）是密切相关的。 与老化/衰老有关。 除了它们在基因中的作用外， 激活，这些都是不变的遗传毒性，并诱导大量的 核和线粒体中的诱变和毒性损伤 基因组 DNA损伤通过碱基切除修复来修复 (BER)AP-内切核酸酶（APE）参与的途径。 主要 哺乳动物APE（称为APE/Ref-1），在哺乳动物中的限速酶， 核DNA损伤的BER，也负责还原 激活AP-1，一种主要的转录因子，并可能作为一种 甲状旁腺激素和其他基因的阻遏物，包括它自己的。 特别是，APE/Fer-1基因被ROS激活，导致 增强氧化DNA损伤的修复。 是否 线粒体APE（APE-m），可能参与线粒体 DNA修复也被ROS激活。 其主要目标是 该项目旨在确定年龄依赖性和ROS之间的联系- APE/Ref-1（和可能的APE-m）的调节表达， ROS诱导的核和线粒体基因组损伤。 使用大鼠和小鼠组织以及原代人成纤维细胞， 将进行系统研究，以确定各种参数， 影响APE表达。 具体而言，该项目将：（1）测试 APE/Ref-1活性氧激活及其基础水平 APE/Ref-1水平的变化是次要的应激反应 转录因子 谷胱甘肽的作用，防止ROS 影响，以及信号中间体的酪氨酸磷酸化，将 使用适当的转基因小鼠突变体进行检测。 这 项目还将（4）测试表达的假设， 在APE活化和BER中，线粒体APE-m是O2。 超氧 将使用dismutase阴性小鼠来检查通过以下测试的作用： (5)确定热量重建对年龄依赖性 APE的变化。 这项研究的结果有望提供一个重要的 了解ROS在细胞内复杂的和连锁的功能， DNA损伤及其修复，并可能提出减少 衰老过程中持续DNA损伤的水平。

Endo- and exogenous reactive oxygen species (ROS) are intimately involved in aging/senescence. In addition to their role in gene activation, these are invariable genotoxic, and induce a multitude of mutagenic and toxic lesions in in both nuclear and mitochondrial genomes. The DNA damage is repaired via the base excision repair (BER) pathway involving AP-endonuclease (APE). The major mammalian APE (called APE/Ref-1), the rate-linimting enzyme in BER of nuclear DNA lesions, is also responsible for reductive activation of AP-1, a major transcription factor, and may act as a repressor of parathyroid hormone and other genes including its own. Paradoxically, APE/Fer-1 gene is activated by ROS, leading to enhanced repair of oxidative DNA damage. Whether the mitochondrial APE (APE-m), presumably involved in mitochondrial DNA repair, is also activated by ROS. The broad objective of this project is to identify the linkage between age-dependent and ROS- regulated expression of APE/Ref-1 (and possible APE-m) with repair of ROS-induced damage of nuclear and mitochondrial genomes. Using rat and mouce tissues and primary human fibroblasts, a systematic study will be carried out to identify various parameters that affect APE expression. Specifically, the project will: (1) test the hypothesis that ROS activation of APE/Ref-1 as well as its basal levle are APE/Ref-1 levle are secondary to the changes in stress-responsive transcription factors. The roles of glutathione that prevents ROS effects, and of tyrosine phosphorylation of signalling intermediates, will be examine dusing appropriate transgenic mouse mutants. This project will also (4) test the hypothesis that expression of mitochondrial APE-m is O2 in APE activation and BER. Superoxide dismutase-negative mice will be used to examine the role of tested by (5) determining the effect of caloric restruction on age-dependent changes in APEs. The ruslts from this study are expected to provide a significant understanding of the complex andinterlocking fucntions of ROS in DNA damage and its repair, and could suggest approaches to reduce the level of persistent DNA dmanage during aging/senescence.