MARS2 drives metabolic switch of non-small-cell lung cancer cells via interaction with MCU

Mitochondrial methionyl-tRNA synthetase (MARS2) canonically mediates the formation of fMet-tRNA(i)(fMet) for mitochondrial translation initiation. Mitochondrial calcium uniporter (MCU) is a major gate of Ca(2+) flux from cytosol into the mitochondrial matrix. We found that MARS2 interacts with MCU and stimulates mitochondrial Ca(2+) influx. Methionine binding to MARS2 would act as a molecular switch that regulates MARS2-MCU interaction. Endogenous knockdown of MARS2 attenuates mitochondrial Ca(2+) influx and induces p53 upregulation through the Ca(2+)-dependent CaMKII/CREB signaling. Subsequently, metabolic rewiring from glycolysis into pentose phosphate pathway is triggered and cellular reactive oxygen species level decreases. This metabolic switch induces inhibition of epithelial-mesenchymal transition (EMT) via cellular redox regulation. Expression of MARS2 is regulated by ZEB1 transcription factor in response to Wnt signaling. Our results suggest the mechanisms of mitochondrial Ca(2+) uptake and metabolic control of cancer that are exerted by the key factors of the mitochondrial translational machinery and Ca(2+) homeostasis.