Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, California, United States of America.
PLoS One. 2012;7(11):e50644. doi: 10.1371/journal.pone.0050644. Epub 2012 Nov 30.
Defects in mitochondrial electron transport chain (ETC) function have been implicated in a number of neurodegenerative disorders, cancer, and aging. Mitochondrial complex I (NADH dehydrogenase) is the largest and most complicated enzyme of the ETC with 45 subunits originating from two separate genomes. The biogenesis of complex I is an intricate process that requires multiple steps, subassemblies, and assembly factors. Here, we report the generation and characterization of a Drosophila model of complex I assembly factor deficiency. We show that CG7598 (dCIA30), the Drosophila homolog of human complex I assembly factor Ndufaf1, is necessary for proper complex I assembly. Reduced expression of dCIA30 results in the loss of the complex I holoenzyme band in blue-native polyacrylamide gel electrophoresis and loss of NADH:ubiquinone oxidoreductase activity in isolated mitochondria. The complex I assembly defect, caused by mutation or RNAi of dCIA30, has repercussions both during development and adulthood in Drosophila, including developmental arrest at the pupal stage and reduced stress resistance during adulthood. Expression of the single-subunit yeast alternative NADH dehydrogenase, Ndi1, can partially or wholly rescue phenotypes associated with the complex I assembly defect. Our work shows that CG7598/dCIA30 is a functional homolog of Ndufaf1 and adds to the accumulating evidence that transgenic NDI1 expression is a viable therapy for disorders arising from complex I deficiency.
线粒体电子传递链（ETC）功能的缺陷与许多神经退行性疾病、癌症和衰老有关。线粒体复合物 I（NADH 脱氢酶）是 ETC 中最大和最复杂的酶，由来自两个独立基因组的 45 个亚基组成。复合物 I 的生物发生是一个复杂的过程，需要多个步骤、亚基和组装因子。在这里，我们报告了一种果蝇模型的产生和特征，该模型缺乏复合物 I 组装因子。我们表明，CG7598（dCIA30），即人类复合物 I 组装因子 Ndufaf1 的果蝇同源物，对于正确的复合物 I 组装是必需的。dCIA30 的表达减少导致在蓝色非变性聚丙烯酰胺凝胶电泳中失去复合物 I 全酶带，并导致分离的线粒体中 NADH：泛醌氧化还原酶活性丧失。由 dCIA30 的突变或 RNAi 引起的复合物 I 组装缺陷，在果蝇的发育和成年期都有影响，包括在蛹期发育停滞和成年期应激抗性降低。酵母单亚基替代 NADH 脱氢酶 Ndi1 的表达可以部分或完全挽救与复合物 I 组装缺陷相关的表型。我们的工作表明，CG7598/dCIA30 是 Ndufaf1 的功能同源物，并增加了越来越多的证据表明，转基因 NDI1 表达是治疗复合物 I 缺陷引起的疾病的可行疗法。
