Mitochondrial DNA damage and repair in neurodegeneration

有证据表明，氧化应激和线粒体功能障碍可能参与了 与亨廷顿病（HD）相关的神经变性。然而，尚不清楚是否 线粒体DNA（mtDNA）的氧化损伤和这种损伤的修复是主要的 HD神经发病机制中的事件。线粒体功能障碍和增加的 脑内产生的活性氧（ROS）可能导致神经退行性变 与HD有关。我们推测，线粒体功能障碍可能是由于线粒体DNA损伤水平增加和修复缺陷而发生的。在这项研究中，我们将确定mtDNA损伤和修复与HD中观察到的神经变性之间的关系。为此，我们将使用转基因小鼠HD模型和使用线粒体毒素3-硝基丙酸（3-NPA）的化学诱导HD模型。本研究的具体目的是：1）确定HD转基因动物模型中线粒体DNA损伤和蛋白质表达水平的脑区域差异，以及向HD转基因动物施用超氧化物歧化酶（SOD）模拟物是否可以减轻氧化应激和疾病的发作; 2）建立小鼠神经元细胞模型，研究线粒体DNA损伤、线粒体功能丧失、和细胞死亡后暴露于3-NPA和SOD模拟物的管理所产生的影响;和3）确定碱基切除修复基因在3-NPA修复中的作用。在小鼠原代神经元细胞培养物中诱导线粒体DNA损伤。这项研究将导致更好地了解与liD相关的神经退行性变，特别强调mtDNA损伤，mtDNA损伤修复和线粒体功能障碍的作用。

Evidence suggests that oxidative stress and mitochondrial dysfunction may be involved in neurodegeneration associated with Huntington's disease (HD). However, it is not clear whether oxidative damage to the mitochondrial DNA (mtDNA) and the repair of this damage are primary events in the neuropathogenesis of HD. Mitochondrial dysfunction and increased production of mitochondrial-generated reactive oxygen species (ROS) may contribute to neurodegeneration associated with HD. We hypothesize that mitochondrial dysfunction may occur as a consequence of increased levels of mtDNA damage and deficient repair. In this research proposal we will determine the relationship between mtDNA damage and repair and the neurodegeneration observed in HD. For this purpose we will use a transgenic mouse model of HD and a chemically-induced HD model using the mitochondrial toxin 3-nitropropionic acid (3-NPA). The specific aims of this study are: 1) to determine brain regional differences in the levels of mitochondrial DNA damage and protein expression in a transgenic animal model of HD and if administration of superoxide dismutase (SOD) mimetics to the HD transgenic animals can attenuate oxidative stress and onset of the disease; 2) to develop a mouse neuronal cell model to study the relationship between mitochondrial DNA damage, loss of mitochondrial function, and cell death after exposure to 3-NPA and the effects resulting from administration of SOD mimetics; and 3) to determine the role of base excision repair genes in the repair of 3-NPA-induced mitochondrial DNA damage in mouse primary neuronal cell cultures. This study will lead to a better understanding of mitochondrial-linked neurodegeneration associated with liD, with particular emphasis in the role of mtDNA damage, repair of mtDNA damage, and mitochondrial dysfunction.