MITOCHONDRIAL DNA DAMAGE AND REPAIR

线粒体 DNA 损伤与修复

• 批准号: 6301318
• 负责人: DANIEL F. BOGENHAGEN
• 金额: $ 21.9万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-04-10 至 2001-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6301318
• 关键词: DNA damage; DNA directed DNA polymerase; DNA repair; DNA replication; adenine; cytosine; endonuclease; environmental toxicology; enzyme activity; mitochondrial DNA; mitochondrial disease /disorder; molecular genetics; oxidative stress

Mutations in mitochondrial DNA (mtDNA) cause a number of human diseases such as MELAS (mitochondrial encephalopathy lactic acidosis and stroke) and LHON (Leber's hereditary optic neuropathy) and may contribute to the pathogenesis of other more common diseases, including Parkinson's disease and diabetes. These mutations reflect an inadequacy of mtDNA repair processes and indicate that more detailed understanding of DNA repair processes in mitochondria is required. Recent studies have shown that some types of damage, mainly those amenable to base excision repair, can be repaired in mtDNA. The base excision repair pathway handles abasic sites in mtDNA produced by spontaneous base loss or by any of several damage-specific glycosylases. Some nuclear genes for glycosylases involved in repair of oxidative DNA damage provide enzyme to both the nucleus and to mitochondria. Our laboratory has recently reconstituted a complete pathway for base excision repair of mtDNA with proteins purified from mitochondria. We propose experiments to characterize mitochondrial glycosylases that act on 3- methyl adenine residues in order to test the hypothesis that mitochondrial contain a variant of the cellular alkyl adenine glycosylase. This enzyme may also process endogenous damage generated by reaction of lipid peroxidation products with mtDNA. Abasic site repair requires an enzyme to cleave abasic sites, AP (apurinic/apyrimidinic) endonuclease. We also propose a series of experiments to characterize the mitochondrial AP endonuclease. Finally, we propose to apply our expertise in mtDNA repair to investigate the mechanism whereby an environmental toxin known to cause Parkinson's disease interferes with the initiation of mtDNA replication. We will test the hypothesis that this inhibition results from the sequestration of DNA polymerase gamma at sites of DNA damage.

线粒体 DNA (mtDNA) 突变会导致多种人类疾病，例如 MELAS（线粒体脑病、乳酸性酸中毒和中风）和 LHON（莱伯遗传性视神经病），并可能导致其他更常见疾病的发病机制，包括帕金森病和糖尿病。这些突变反映了线粒体DNA修复过程的不足，并表明需要更详细地了解线粒体中的DNA修复过程。最近的研究表明，某些类型的损伤，主要是那些适合碱基切除修复的损伤，可以在 mtDNA 中修复。碱基切除修复途径处理 mtDNA 中由自发碱基丢失或由几种损伤特异性糖基化酶中的任何一种产生的脱碱基位点。一些参与修复氧化 DNA 损伤的糖基化酶核基因为细胞核和线粒体提供酶。我们的实验室最近用从线粒体中纯化的蛋白质重建了线粒体DNA碱基切除修复的完整途径。我们提出实验来表征作用于 3-甲基腺嘌呤残基的线粒体糖基化酶，以检验线粒体含有细胞烷基腺嘌呤糖基化酶变体的假设。这种酶还可以处理脂质过氧化产物与 mtDNA 反应产生的内源性损伤。 脱碱基位点修复需要一种酶来切割脱碱基位点，即 AP（脱嘌呤/脱嘧啶）核酸内切酶。我们还提出了一系列实验来表征线粒体 AP 核酸内切酶。最后，我们建议运用我们在 mtDNA 修复方面的专业知识来研究已知导致帕金森病的环境毒素干扰 mtDNA 复制起始的机制。我们将检验这一假设，即这种抑制是由于 DNA 聚合酶 γ 在 DNA 损伤位点的隔离所致。