Causes and Consequences of Mitochondrial Mutations

项目总结 所有复杂的真核生物都依赖线粒体来产生维持正常状态所需的细胞能量 生物体功能。线粒体基因组的突变是多种疾病的致病原因之一 建议发挥抗衰老的综合作用。然而，了解原因和后果 线粒体突变受到对哺乳动物模型的关注的限制。我们将描述线粒体的特征 各种真核生物系统中的突变及其对生理的影响，包括无脊椎动物、植物和 微型真核生物。我们将解决三个阻碍我们理解线粒体的挑战 突变。首先，我们将使用高保真测序来表征线粒体的速率和类型 跨真核生物和不同环境下的突变(例如，氧化应激增加)，导致 《线粒体突变图谱》。尤其令人感兴趣的是由以下因素引起的C-T；T转变的频率 复制错误与以氧化损伤为特征的G-gt；T颠换。后者与衰老有关 理论，但前者已被证明主导着哺乳动物线粒体的突变图景 基因组。其次，我们将量化氧化磷酸化的不同状态，即活性氧物种(ROS) 具有不同来源和不同线粒体突变率的系统中的产量和代谢率 确定突变如何影响细胞器和有机体的特征。我们还将探索一种机械联系 氧化应激与线粒体突变之间的关系--通过超氧化物歧化酶增加ROS 击倒对手。第三，我们将研究两个谱系中的有丝分裂蛋白和转录平衡 相关的生物有不同的寿命：岩鱼和洞穴火蜥蜴。向精简的转变 线粒体蛋白丰度已被确认为长寿的一种保守机制 小鼠和线虫的品系，但尚不清楚自然长寿种群是否改变了有丝分裂核 蛋白质平衡。我们还将对这些物种的线粒体突变和生理学进行量化，以确定 自然选择是如何通过线粒体过程塑造衰老的。总体而言，这项研究将 补充了以前在哺乳动物模型上的工作，这些模型显示出一致的高线粒体 突变率。它将进一步揭示线粒体突变影响细胞和 生物体过程，对人类健康、疾病进展和衰老的影响。

PROJECT SUMMARY All complex eukaryotes rely on mitochondria to generate the cellular energy needed to maintain proper organismal function. Mutations in the mitochondrial genome underly multiple diseases and have been suggested to play a general role in aging. However, understanding the causes and consequences of mitochondrial mutations is limited by a focus on mammalian models. We will characterize mitochondrial mutations and their effects on physiology in diverse eukaryotic systems, including invertebrates, plants, and micro-eukaryotes. We will address three challenges that have hindered our understanding of mitochondrial mutations. First, we will use high-fidelity sequencing to characterize rates and types of mitochondrial mutations across eukaryotes and under different environments (e.g., increased oxidative stress), resulting in a “mitochondrial mutation atlas”. Of particular interest is the frequency of C -> T transitions resulting from replication errors vs. G -> T transversions characteristic of oxidative damage. The latter are implicated in aging theories, but the former have been shown to dominate the mutational landscape in mammalian mitochondrial genomes. Second, we will quantify distinct states of oxidative phosphorylation, reactive oxygen species (ROS) production, and metabolic rate in systems with varying sources and rates of mitochondrial mutations to determine how mutations affect organelle and organismal traits. We will also explore a mechanistic link between oxidative stress and mitochondrial mutations by increasing ROS via superoxide dismutase knockdown. Third, we will examine mitonuclear protein and transcript balance in two lineages where closely related organisms have disparate lifespans: rockfishes and cave salamanders. A shift towards reduced mitochondrial protein abundances has been identified as a conserved mechanism of longevity in long-lived strains of mice and nematodes, but it is unknown if natural long-lived populations have altered mitonuclear protein balance. We will also quantify mitochondrial mutations and physiology in these species to determine how natural selection may have shaped aging through mitochondrial processes. Overall, this research will provide a complement to previous work on mammalian models, which show uniformly high mitochondrial mutation rates. It will further uncover the possibilities for mitochondrial mutations to influence cellular and organismal processes, with implications for human health, disease progression, and aging.