Reductive Stress in Complex I Deficiency

描述（由申请人提供）：线粒体是细胞生物能量学的中心调节器。线粒体在代谢、能量产生和活性氧产生中起着关键作用，许多人类疾病都与线粒体功能障碍有关。在这些疾病中，遗传性氧化磷酸化失调是最常见的一组先天性代谢错误。孤立性复合体I缺乏症是最常见的遗传性氧化磷酸化疾病，可导致多种严重的代谢疾病。复合I缺乏症患者有一系列的临床表现，特别反映了大脑、心脏和骨骼肌的受累。利氏病是一种致命的脑肌病，是最常见的临床综合征。孤立的复合体I缺乏症通常会在生命的头两年内导致死亡，并且没有有效的治疗方法。虽然对复合体I的结构和生化功能已经有了相当多的了解，但在与复合体I缺乏相关的疾病中导致细胞功能障碍和死亡的机制却知之甚少。动物模型的缺乏导致对复合物I缺乏发病机制的了解进展缓慢。为了解决这些问题并允许对复合物I缺乏症进行详细的遗传分析，我们在简单的遗传模式生物果蝇中建立了这种疾病的模型。初步的基因修饰分析结果使我们提出了一个新的假设来解释复合体I的发病机制：过量还原等价物的积累导致还原性应激。我们现在将使用遗传学和生物化学的结合来测试还原性应激在复合体I缺乏症中的作用。我们将首先对导致NADH产生和代谢的酶促途径进行遗传解剖，NADH是复合物I的关键底物。然后，我们将使用生化分析直接测量复合物I功能改变的动物的还原当量水平，以及在转基因背景下的复合物I模型。如果成功，我们的研究将验证一个关于复合物I缺乏发病机制的新假设，从而为开发新的治疗方法奠定基础。

DESCRIPTION (provided by applicant): Mitochondria are central regulators of cellular bioenergetics. Reflecting the critical role for mitochondria in metabolism, energy production, and production of reactive oxygen species, a wide range of human diseases have been linked to mitochondrial dysfunction. Included in these, genetic oxidative phosphorylation disorders represent the most common group of inborn errors of metabolism. Isolated complex I deficiency is the most frequent inherited oxidative phosphorylation disorder and leads to a variety of severe metabolic diseases. Patients with complex I deficiency have a range of clinical presentations that reflect particularly involvement of the brain, heart and skeletal muscle. Leigh's disease, a fatal encephalomyopathy, is the most common clinical syndrome. Isolated complex I deficiency usually leads to death within the first two years of life and there is no effective treatment. Although a substantial amount is know regarding the structure and biochemical function of complex I, the mechanisms leading to cellular dysfunction and death in diseases associated with complex I deficiency are much less well understood. A paucity of animal models has contributed to the slow progress in understanding the pathogenesis of complex I deficiency. To address these issues and allow for a detailed genetic analysis of complex I deficiency, we have modeled the disorder in the simple genetic model organism Drosophila. Results of preliminary genetic modifier analyses lead us to propose a novel hypothesis to explain complex I pathogenesis: accumulation of excess reducing equivalents leading to reductive stress. We will now test the role of reductive stress in complex I deficiency using a combination of genetics and biochemistry. We will first perform a genetic dissection of the enzymatic pathways leading to the production and metabolism of NADH, a critical substrate of complex I. We will then use biochemical assays to measure directly the levels of reductive equivalents in animals with altered complex I function, and in our complex I model in the context of genetically modified backgrounds. If successful, our studies will validate a novel hypothesis regarding the pathogenesis of complex I deficiency and thus set the stage for development of new therapeutic approaches.