biostudies-literatureUnknown27(2)Shan ZFundamental Research Funds for the Central UniversitiesNational Natural Science Foundation of ChinaA high ratio of severe mitochondrial defects causes multiple human mitochondrial diseases. However, until now, the <i>in vivo</i> rescue signal of such mitochondrial defect effects has not been clear. Here, we built fly mitochondrial defect models by knocking down the essential mitochondrial genes <i>dMterf4</i> and <i>dMrps23</i>. Following genome-wide RNAi screens, we found that knockdown of <i>Med8/Tfb4/mtSSB/PolG2/mtDNA-helicase</i> rescued <i>dMterf4/dMrps23</i> RNAi-mediated mitochondrial defect effects. Extremely surprisingly, they drove mtDNA replication outside mitochondria through the Med8/Tfb4-mtSSB/PolG2/mtDNA-helicase axis to amplify cytosolic mtDNA, leading to activation of the cGAS-Sting-like IMD pathway to partially mediate <i>dMterf4</i>/<i>dMrps23</i> RNAi-triggered effeciScience108970https://www.ebi.ac.uk/biostudies/studies/S-EPMC10844862biostudies-literaturemtDNA extramitochondrial replication mediates mitochondrial defect effects.PMC10844862Li SJian CShan ZZuo HGao YZhao GTi XWang YZhang QfalsemtDNA extramitochondrial replication mediates mitochondrial defect effects.A high ratio of severe mitochondrial defects causes multiple human mitochondrial diseases. However, until now, the <i>in vivo</i> rescue signal of such mitochondrial defect effects has not been clear. Here, we built fly mitochondrial defect models by knocking down the essential mitochondrial genes <i>dMterf4</i> and <i>dMrps23</i>. Following genome-wide RNAi screens, we found that knockdown of <i>Med8/Tfb4/mtSSB/PolG2/mtDNA-helicase</i> rescued <i>dMterf4/dMrps23</i> RNAi-mediated mitochondrial defect effects. Extremely surprisingly, they drove mtDNA replication outside mitochondria through the Med8/Tfb4-mtSSB/PolG2/mtDNA-helicase axis to amplify cytosolic mtDNA, leading to activation of the cGAS-Sting-like IMD pathway to partially mediate <i>dMterf4</i>/<i>dMrps23</i> RNAi-triggered effec2024-01-01T00:00:00Z2024 Feb2025-04-22T03:17:42.227Z2025-04-05T20:40:36.212ZS-EPMC108448623832298710.1016/j.isci.2024.108970