Mitochondrial DNA genotypes modify m.3243A>G-associated mitochondrial disease via the 15-HETE/Akt/FoxO1 pathway

Abstract

Mitochondrial disease caused by mitochondrial DNA (mtDNA) 3243A>G mutation is characterized by high levels of clinical heterogeneity. Varied m.3243A>G mutation loads among patients are used to, but cannot fully explain, disease heterogeneity. Here, we found that mtDNA genotypes (haplogroups) modify m.3243A>G-associated natural selection and cell fate determination. mtDNA haplogroup M7 was less prevalent in a multi-center m.3243A>G disease cohort. Further functional studies using cybrids showed that M7 accelerated cell proliferation and shortened G0/G1 cell cycle when compared with cybrid carrying a non-M7 haplogroup (D5). However, mitochondrial function and cell viability were even worse in M7 cybrid than D5 cybrid when treated with mitochondrial oxidative phosphorylation (OXPHOS) inhibitors, indicating that M7 drives negative selection in patients with m.3243A>G during evolution. By adopting multi-omics strategies, we showed a lesser increase of 15-hydroxyeicosatetraenoic acid (15-HETE) levels in M7 cybrid owing to OXPHOS inhibition, leading to insufficient Akt/FoxO1 activation and increased apoptosis. Notably, 15-HETE administration activated Akt/FoxO1 phosphorylation and abolished apoptosis difference between M7 and D5 cybrids, suggesting that augmented 15-HETE was vital to protect cells from death. Collectively, our work identified a genetic modifier of m.3243A>G-associated mitochondrial disease and demonstrated that the mitochondrial retrograde 15-HETE/Akt/FOXO1 signaling cascade plays an important role in protecting cells from OXPHOS dysfunction-induced cell death.