Data from: Screen for mitochondrial DNA copy-number maintenance genes reveals essential role for ATP synthase

The machinery of mitochondrial DNA (mtDNA) maintenance is only partially characterized and is of wide interest due to its involvement in disease. To identify novel components of this machinery, plus other cellular pathways required for mtDNA viability, we implemented a genome-wide RNAi screen in Drosophila S2 cells, assaying for loss of fluorescence of mtDNA nucleoids stained with the DNA-intercalating agent PicoGreen. In addition to previously characterized components of the mtDNA replication and transcription machineries, positives included many proteins of the cytosolic proteasome and ribosome (but not the mitoribosome), three proteins involved in vesicle transport, some other factors involved in mitochondrial biogenesis or nuclear gene expression, > 30 mainly uncharacterized proteins and most subunits of ATP synthase (but no other OXPHOS complex). ATP synthase knockdown precipitated a burst of mitochondrial ROS production, followed by copy number depletion involving increased mitochondrial turnover, not dependent on the canonical autophagy machinery. Our findings will inform future studies of the apparatus and regulation of mtDNA maintenance, and the role of mitochondrial bioenergetics and signaling in modulating mtDNA copy number.线粒体DNA（mtDNA）的维持机制仅得到部分阐明，且因其参与疾病进程而受到广泛关注。为鉴定该维持机制的新型组分，以及维持mtDNA存活所需的其他细胞通路，我们在果蝇S2细胞中开展了全基因组RNA干扰（RNAi）筛选，通过检测经DNA嵌入剂PicoGreen染色的mtDNA类核的荧光衰减来实现筛选。除已被表征的mtDNA复制与转录机制组分外，筛选阳性靶点还包括众多胞质蛋白酶体与核糖体（而非线粒体核糖体）蛋白、三种参与囊泡运输的蛋白质、部分与线粒体生物发生或核基因表达相关的其他因子、超过30种主要未被表征的蛋白质，以及ATP合酶的绝大多数亚基（而非其他氧化磷酸化（OXPHOS）复合物）。敲低ATP合酶的表达会引发线粒体活性氧（ROS）爆发，随后出现mtDNA拷贝数降低，该过程伴随线粒体周转增加，且不依赖于经典自噬机制。本研究结果将为未来解析mtDNA维持的相关装置及其调控机制，以及线粒体生物能学与信号通路在调控mtDNA拷贝数中的作用提供参考。