Interaction Between DNA Repair and Antioxidant Genes During Aging

描述（由申请人提供）：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（ROS）的主要来源，对大分子，尤其是线粒体造成损伤！DNA (mtDNA)。DMA损伤对细胞是有害的，因为它们会停止转录、复制并产生突变。细胞已经进化出几种机制来处理氧化损伤。一道防线由抗氧化防御系统代表，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。虽然这两种防御系统的酶成分都是已知的，但尚不清楚这些系统如何相互作用以维持线粒体基因组的稳定性。本研究建议的主要假设是，BER通路和抗氧化防御系统在防止氧化应激诱导的线粒体基因组不稳定中具有协同作用。氧化应激将在两种情况下被考虑：在衰老过程中和在环境诱导的侮辱之后。为了验证这一假设，我们将使用两种模式生物，一种是简单的真核生物，酵母酿酒酵母，另一种是更复杂的哺乳动物生物，一种敲除小鼠杂合的Ape1，参与BER的主要AP内切酶。以下具体目标将作为检验我们假设的标准：(1)确定APN1和SOD2基因同时突变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APN1和SOD2基因同时突变的酵母细胞中，mtDNA病变水平是否以年龄依赖的方式增加，以及mtDNA病变水平是否与线粒体功能障碍相关；(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，其目标是引导PI改善他的发表记录，并生成提交非score竞争性研究资助所需的初步数据。

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.