Mechanisms of mitochondrial disease suppression in Ndufs4 knockout mice

7.项目总结/摘要 线粒体电子传递链复合体I中的缺陷代表了一类重要的人类 线粒体疾病，包括Leigh综合征，Leber遗传性视神经肾病，新生儿乳酸 酸中毒心肌病和脑病利氏综合征通常被认为是最常见的 线粒体疾病是婴儿期的疾病，其主要特征是严重的神经缺陷。有 目前没有有效的治疗方法。已经开发了一种小鼠模型，其中复合物I结构亚基 NDUFS 4被淘汰。NDUFs 4-/-小鼠表现出严重的神经退行性表型，包括发育迟缓 生长速度、嗜睡、运动技能丧失、失明、体重减轻和过早死亡。这些症状 在具有Ndufs 4突变以及其他Leigh综合征相关突变的人类患者中重现。 我们最近报道了用药物雷帕霉素治疗Ndufs 4-/-小鼠，雷帕霉素是一种特异性的 雷帕霉素复合物1的哺乳动物靶标（mTORC 1），导致存活率增加2至3倍， 神经缺陷的显著减弱和神经变性的减少。在未发表的研究中， 观察到NAD+前体烟酰胺单核苷酸（NMN）-葡萄糖苷酶的类似作用 抑制剂阿卡波糖。更广泛的目标，这项建议，以确定机制的基础上，抑制 在Ndufs 4敲除（KO）小鼠中，雷帕霉素、NMN和阿卡波糖引起的线粒体疾病。这将是 通过评估代谢组和磷酸化蛋白质组的变化，特别是通过 确定这些干预对线粒体功能、mTOR信号传导、NAD稳态的影响， 和NAD依赖性线粒体SIRT 3脱乙酰酶的活性。我们将检验以下特定假设： 这些干预通过产生缺乏NDUFS 4和SIRT 3的动物来增强SIRT 3活性， 确定这是否阻断或减弱疾病的挽救。这些研究有望提高我们的 理解线粒体功能的背景下，复杂的I缺乏，并促进发展， 改善线粒体疾病患者生活的干预策略。

7. Project Summary/Abstract Deficiencies in complex I of the mitochondrial electron transport chain represent an important class of human mitochondrial diseases that include Leigh Syndrome, Leber’s hereditary optic nephropathy, neonatal lactic acidosis, cardiomyopathy, and encephalopathy. Leigh Syndrome is generally regarded as the most common mitochondrial disease of infancy and is characterized primarily by severe neurological defects. There is currently no effective treatment. A mouse model has been developed in which the complex I structural subunit NDUFS4 is knocked-out. Ndufs4-/- mice show a profound neurodegenerative phenotype including retarded growth rate, lethargy, loss of motor skill, blindness, weight loss, and early death. These symptoms are recapitulated in human patients with Ndufs4 mutations, as well as other Leigh Syndrome-associated mutations. We have recently reported that treating Ndufs4-/- mice with the drug rapamycin, a specific inhibitor of the mammalian target of rapamycin complex 1 (mTORC1), results in two to three-fold increase in survival, dramatic attenuation of neurologial defecits, and reduced neurodegeneration. In unpublished studies, we have observed similar effects from the NAD+ precursor nicotinamide mononucleotide (NMN) -glucosidase inhibitor acarbose. The broader goals this proposal to define the mechanistic basis for suppression of mitochondrial disease by rapamycin, NMN, and acarbose in the Ndufs4 knockout (KO) mouse. This will be accomplished broadly by assessing changes in the metabolome and phosphoproteome, and specifically by determining the effects of these interventions on mitochondrial function, mTOR signaling, NAD homeostasis, and activity of the NAD-dependent mitochondrial SIRT3 deacetylase. We will test the specific hypothesis that these intervention act by enhancing SIRT3 activity by creating animals lacking both NDUFS4 and SIRT3 and determining whether this blocks or attenuates rescue of the disease. These studies promise to enhance our understanding of mitochondrial function in the context of complex I deficiency and facilitate the development of interventional strategies to improve the lives of patients with mitochondrial disease.