Molecular and Physiological Responses to Persistent Mitochondrial DNA Damage

描述(申请人提供)：这项研究的目标是阐明持久性线粒体DNA(MtDNA)损伤时发生的生理和分子反应。线粒体DNA的完整性对人类健康至关重要，而线粒体DNA对许多造成DNA损伤的化学物质比核DNA(NDNA)更敏感。然而，人们对未修复的线粒体DNA损伤的后果知之甚少。此外，由于线粒体显然缺乏处理核基因组中此类损伤的修复蛋白，因此对环境基因毒素，如紫外线C辐射(UVC)和多环芳烃损伤的mtDNA的命运也知之甚少。该项目将阐明线粒体DNA损伤的命运，并检验通过分裂/融合和自噬从强大的模式生物秀丽线虫中清除严重损伤的线粒体DNA的假设。我们最近观察到，在生命早期暴露于巨大的(UVC诱导的)mtDNA损伤会导致线虫的发育延迟，也会导致成年线虫的神经退化，这表明线虫将是哺乳动物对这种损伤做出反应的合适且强大的模型。为了更好地理解对这种损伤的毒理学反应的时间进程和机制细节，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：特定目标1.检验在发育早期暴露于持续的线粒体DNA损伤导致线粒体功能障碍的假设。我们将测量携带持续mtDNA损伤的线虫的线粒体功能和功能障碍。具体目标2.测试在发育早期暴露于持续的线粒体DNA损伤会导致成人神经退化的假设。许多神经退行性疾病与环境因素有关，暴露于线粒体毒物与神经退行性疾病有关。我们将测试早期暴露在持续线粒体DNA损伤下的线虫是否会在以后的生活中导致神经退化。具体目的3.验证线粒体基因组中存在的大量DNA加合物通过线粒体融合、分裂和自噬被移除的假设。这一假说将通过使用基因敲除和基因敲除技术进行验证。公共卫生相关性：线粒体DNA完整性对人类健康至关重要，但持续性线粒体DNA损伤导致生理结果的机制以及处理此类损伤的途径尚不清楚。这项研究将提供对我们理解线粒体功能障碍引起疾病的遗传和环境因素至关重要的信息。

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.