The Role of Mitophagy in the Differentiation of Human iPSCs

Pluripotent stem cells shift their mitochondrial metabolism upon differentiation but the mechanisms underlying such a metabolic rewiring are not fully understood. We hypothesized that during differentiation of human induced pluripotent stem cells (hiPSCs), mitochondria undergo mitophagy and are then replenished by the biogenesis of new mitochondria adapted to the metabolic needs of the differentiated cell. We observed a burst of mitophagy during the initial phases of hiPSC differentiation into the endothelial lineage, followed by subsequent mitochondrial biogenesis using the mitochondrial biogenesis biosensor MitoTimer. Differentiating iPSCs generated greater amounts of ATP from fatty acid oxidation than undifferentiated hiPSCs which relied on glutamine metabolism. We also found that the mitochondrial phosphatase PGAM5 is cleaved in hiPSC-derived endothelial progenitor cells and activates β-catenin-mediated transcription of the transcriptional co-activator PGC-1α which regulates mitochondrial biogenesis. These findings reveal a mitophagy-mediated mechanism for metabolic rewiring and maturation of differentiating cells via the β-catenin pathway. Such a mitochondrial-nuclear crosstalk during hiPSC differentiation could be leveraged to enhance the metabolic maturation of differentiated cells.