Molecular and Physiological Responses to Persistent Mitochondrial DNA Damage

描述（由申请人提供）：本研究的目的是阐明对持续线粒体DNA （mtDNA）损伤的生理和分子反应。线粒体DNA的完整性对人类健康至关重要，而且线粒体DNA比核DNA （nDNA）对许多导致DNA损伤的化学物质更为敏感。然而，对未修复mtDNA损伤的后果了解甚少。此外，由于线粒体显然缺乏处理核基因组中这种损伤的修复蛋白，因此mtDNA受到环境基因毒素（如紫外线C辐射（UVC）和多环芳烃）损伤的命运也知之甚少。该项目将阐明mtDNA损伤的命运，并验证严重损伤的mtDNA通过裂变/融合和自噬从强大的模式生物秀丽隐杆线虫中清除的假设。我们最近观察到，生命早期暴露于大量（uvc诱导的）mtDNA损伤会导致秀丽隐杆线虫发育迟缓，也会导致成人神经退行性变，这表明秀丽隐杆线虫将是哺乳动物对这种损伤反应的合适且强大的模型。为了更好地了解这种损伤的时间进展和毒理学反应的机制细节，我们还将研究早期暴露于持续性mtDNA损伤的分子和生理后果。这项工作将通过以下三个具体目标来完成：验证在发育早期暴露于持续mtDNA损伤导致线粒体功能障碍的假设。我们将测量携带持续性mtDNA损伤的秀丽隐杆线虫的线粒体功能和功能障碍。具体目标2。验证在发育早期暴露于持续mtDNA损伤导致成人神经变性的假设。许多神经退行性疾病都有环境因素，暴露于线粒体毒物与神经退行性疾病有关。我们将测试秀丽隐杆线虫早期暴露于持续的mtDNA损伤是否会导致以后的神经变性。具体目标3。验证线粒体基因组中存在的大体积DNA加合物通过线粒体融合、裂变和自噬被去除的假设。这一假设将通过基因敲除和基因敲除技术进行检验。公共卫生相关性：线粒体DNA完整性对人类健康至关重要，但线粒体DNA持续损伤导致生理结果的机制以及处理这种损伤的途径尚不清楚。这项研究将为我们了解线粒体功能障碍引起的疾病的遗传和环境因素提供关键信息。

DESCRIPTION (provided by applicant): The goal of this research is to elucidate the physiological and molecular responses that occur in response to persistent mitochondrial DNA (mtDNA) damage. Mitochondrial DNA integrity is critical for human health, and mtDNA is more sensitive than nuclear DNA (nDNA) to many chemicals that cause DNA damage. However, the consequences of unrepaired mtDNA damage are poorly understood. Furthermore, since mitochondria apparently lack the repair proteins that would handle such damage in the nuclear genome, the fate of mtDNA damaged by environmental genotoxins, such as ultraviolet C radiation (UVC) and polycyclic aromatic hydrocarbons, is also poorly understood. This project will elucidate the fate of mtDNA damage and test the hypothesis that severely damaged mtDNA is cleared from the powerful model organism Caenorhabditis elegans by fission/fusion and autophagy. We have recently observed that early life stage exposure to bulky (UVC-induced) mtDNA lesions causes developmental delay in C elegans, and also leads to neurodegeneration in adults, suggesting that C elegans will be an appropriate as well as powerful model for the mammalian response to such damage. To better understand the temporal progression and mechanistic details of the toxicological response to such damage, we will also examine the molecular and physiological consequences of early-life exposure to persistent mtDNA damage. This work will be accomplished via the following three Specific Aims: Specific Aim 1. Test the hypothesis that exposure during early development to persistent mtDNA damage leads to mitochondrial dysfunction. We will measure mitochondrial function and dysfunction in C elegans carrying persistent mtDNA damage. Specific Aim 2. Test the hypothesis that exposure during early development to persistent mtDNA damage leads to neurodegeneration in adults. Many neurodegenerative diseases have environmental components, and exposure to mitochondrial toxicants is associated with neurodegenerative disease. We will test whether early-life exposure of C elegans to persistent mtDNA damage leads to neurodegeneration in later life. Specific Aim 3. Test the hypothesis that bulky DNA adducts present in mitochondrial genomes are removed via mitochondrial fusion, fission and autophagy. This hypothesis will be tested via the use of gene knock-out and gene knock-down technologies. PUBLIC HEALTH RELEVANCE: Mitochondrial DNA integrity is critical for human health, but the mechanisms by which persistent mtDNA damage causes physiological outcomes, and the pathways by which such damage is handled, are unclear. This research will yield information critical to our understanding of the genetic and environmental contributors to diseases caused by mitochondrial dysfunction.