MITOCHONDRIAL FREE RADICALS AND AGING

线粒体自由基与衰老

• 批准号: 6043082
• 负责人: Charles J Epstein
• 金额: $ 18.7万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6043082
• 关键词: aging; animal genetic material tag; apoptosis; cellular respiration; electron transport; enzyme activity; fibroblasts; free radical oxygen; gene mutation; genetically modified animals; laboratory mouse; mitochondria; mitochondrial DNA; oxidative stress; superoxide dismutase; superoxides

The proposed studies are based on the hypothesis that cellular and organ aging are, to a significant degree, the consequences of oxygen free radical-mediated mitochondrial aging or impairment resulting from the accumulation of mitochondrial DNA mutations. Despite much indirect evidence, there is, as yet, no direct proof of the mitochondrial hypothesis of aging. However, the ability to modulate the activity of Mn superoxide dismutase (MnSOD) within mitochondria by genetic means makes it possible to assess the role of oxygen free radicals generated by the mitochondria in the aging process. To achieve this modulation of MnSOD activity, mutant mice completely lacking in MnSOD and mice with a low level of MnSOD expression from a transgene bred into the MnSOD deficient stock will be used. The finding that fetal fibroblasts lacking MnSOD are sensitive to atmospheric oxygen and have a shorter replicative life span than normal cells indicates that intramitochondrial superoxide levels can be affected by alteration of MnSOD activity. Mutant mice lacking MnSOD quickly develop a dilated cardiomyopathy and metabolic acidosis and die within 10 days after birth. However, in Specific Aim I, chimeras composed of cells completely lacking MnSOD and wild type cells will be formed, and the survival of the MnSOD-deficient cells exposed to a high level of superoxide will be followed in several organs and in the brain. In this manner it will be possible to assess the vulnerability of different types of cells and of different regions of the brain to free- radical induced mitochondrial damage. In Specific Aim II, the effects of chronically increased exposure to intra-mitochondrial superoxide will be studied in appropriately constructed transgenic animals with 10-30% of normal MnSOD activity. The longevity of these animals will determined, and the long term effects on mitochondrial DNA and the electron transport system will be assessed. In addition, behavioral studies will be carried out to determine whether any changes observed in the brain are correlated with alterations in behavior. These studies represent a new and innovative approach to the direct examination of the role of oxygen free radicals in producing mitochondrial mutations and dysfunction and, in turn, organ and organismal aging. Evidence that mitochondrial free radicals are indeed involved in the aging process would constitute a basis for searching for therapeutic approaches to the modulation of oxygen free radical levels within mitochondria.

拟议的研究基于以下假设：细胞和器官 衰老在很大程度上是无氧的后果 自由基介导的线粒体老化或损伤 线粒体DNA突变的积累。尽管有很多间接的 证据表明，目前还没有直接证据证明线粒体 衰老假说。然而，调节 Mn 活性的能力 线粒体内的超氧化物歧化酶（MnSOD）通过遗传手段使 可以评估氧自由基产生的作用 衰老过程中的线粒体。为了实现 MnSOD 的这种调节 活性、完全缺乏 MnSOD 的突变小鼠和低水平的小鼠 MnSOD 缺陷型转基因的 MnSOD 表达水平 将使用库存。研究发现，胎儿成纤维细胞缺乏 MnSOD 对大气中的氧气敏感，复制寿命较短 高于正常细胞表明线粒体内超氧化物水平 可能会受到 MnSOD 活性改变的影响。突变小鼠缺乏 MnSOD 迅速发展为扩张型心肌病和代谢性酸中毒 并在出生后10天内死亡。然而，在特定目标 I 中，嵌合体 由完全缺乏 MnSOD 的细胞和野生型细胞组成 形成，并且暴露于高浓度的 MnSOD 缺陷细胞的存活 将跟踪多个器官和大脑中的超氧化物水平。 通过这种方式，可以评估 不同类型的细胞和大脑不同区域的自由 自由基引起的线粒体损伤。在特定目标 II 中，效果 长期接触线粒体内超氧化物会增加 在适当构建的转基因动物中进行了研究，其中 10-30% MnSOD 活性正常。这些动物的寿命将决定， 以及对线粒体 DNA 和电子的长期影响 将评估运输系统。此外，行为研究将 以确定大脑中是否观察到任何变化 与行为改变相关。这些研究代表了 直接检验作用的新的和创新的方法 氧自由基产生线粒体突变和 功能障碍，进而导致器官和机体衰老。有证据表明 线粒体自由基确实参与了衰老过程 将为寻找治疗方法奠定基础 线粒体内氧自由基水平的调节。