The role of mitochondrial mRNA translation in cellular communication

Mitochondria are dynamic and heterogeneous organelles that rewire their network and metabolic functions in response to changing cellular needs. To this end, mitochondria integrate a plethora of incoming signals to influence cell fate and survival. A crucial and highly regulated node of cell-mitochondria communication is the translation of nuclear-encoded mitochondrial mRNAs. By controlling and monitoring the spatio-temporal translation of these mRNAs, cells can rapidly adjust mitochondrial function to meet metabolic demands, optimise ATP production and regulate organelle biogenesis and turnover. In this Review, we focus on how RNA-binding proteins that recognise nuclear-encoded mitochondrial mRNAs acutely modulate the rate of translation in response to nutrient availability. We further discuss the relevance of localised translation of these mRNAs for subsets of mitochondria in polarised cells. Finally, we highlight quality control mechanisms that monitor the translation process at the mitochondrial surface and their connections to mitophagy and stress responses. We propose that these processes collectively contribute to mitochondrial specialisation and signalling function.