Interaction Between DNA Repair and Antioxidant Genes During Aging

描述(申请人提供)：衰老的氧化理论提出，与衰老相关的细胞功能下降是由于受损大分子的积累。线粒体是内源性活性氧物种(ROS)的主要来源，ROS对大分子尤其是线粒体造成损伤！DNA(线粒体DNA)。DMA损伤对细胞有害，因为它们阻止转录、复制，并可能产生突变。细胞已经进化出几种机制来处理氧化损伤。一道防线是抗氧化防御系统，其中包括超氧化物歧化酶(SOD)酶。第二道防线是DNA修复，特别是碱基切除修复(BER)。虽然这两个防御系统的酶成分是已知的，但还不清楚这两个系统如何相互作用来维持线粒体基因组的稳定性。这项研究的主要假设是，BER途径和抗氧化防御系统在保护氧化应激诱导的线粒体基因组不稳定方面具有协同作用。氧化应激将在两种情况下被考虑：在衰老期间和在环境诱导的侮辱之后。为了验证这一假设，我们将使用两个模式生物，一个是简单的真核生物，酵母酿酒酵母，另一个是更复杂的哺乳动物生物，一个是参与BER的主要AP内切酶APE1的杂合子敲除小鼠。将以下列特定目标作为检验我们假设的标准：(1)确定同时突变APN1和SOD2基因的酵母细胞在氧化应激后是否表现出增强的mtDNA损伤和线粒体功能障碍；(2)确定在同时突变APN1和SOD2基因的酵母细胞中线粒体DNA损伤水平是否随年龄增加而增加，以及mtDNA损伤水平是否与线粒体功能障碍有关；(3)在BER缺陷小鼠模型中，确定线粒体DNA损伤是否以年龄依赖的方式增加。最后，我们提出了一个发展计划，其目标是领导私人投资改善他的出版记录，并产生提交非分数竞争性研究拨款所需的初步数据。

DESCRIPTION (provided by applicant): The oxidative theory of aging proposes that declines in cellular function associated with aging are due to the accumulation of damaged macromolecules. Mitochondria are the main source of endogenous reactive oxygen species (ROS), which inflict damage to macromolecules, particularly to mitochondria! DNA (mtDNA). DMA lesions are deleterious to cells because they halt transcription, replication, and can generate mutations. Cells have evolved several mechanisms to deal with oxidative damage. One line of defense is represented by the antioxidant defense system, which includes among others, the superoxide dismutase (SOD) enzymes. The second line of defense is DNA repair, particularly base excision repair (BER). Although the enzymatic components of both defense systems are known, it is not understood how the systems interact to maintain mitochondrial genomic stability. The main hypothesis in this research proposal is that the BER pathway and the antioxidant defense system have cooperative roles in protecting against mitochondrial genomic instability induced by oxidative stress. Oxidative stress will be considered under two situations: during aging and after an environmentally induced insult. To test this hypothesis we will use two model organisms, a simple eukaryotic organism, the yeast Saccharomyces cerevisiae, and a more complex mammalian organism, a knockout mouse heterozygous for Ape1, the main AP endonuclease that participates in BER. The following specific aims will be used as criteria to test our hypothesis: (1) To determine whether yeast cells harboring simultaneous mutations in the APN1 and SOD2 genes exhibit enhanced mtDNA damage and mitochondrial dysfunction after oxidative stress; (2) To determine whether the levels of mtDNA lesions increase in an age dependent fashion in yeast cells harboring simultaneous mutations in the APN1 and SOD2 genes, and if levels of mtDNA lesions correlate with mitochondrial dysfunction; (3) To determine whether mitochondrial DNA damage increases in an age-dependent fashion in a BER deficient mouse model. Finally, we propose a developmental plan whose objective is to lead the PI to improve his publication record and generate the preliminary data necessary for the submission of non-SCORE competitive research grants.