Many epithelial cancers show cell cycle dysfunction tightly correlated with the overexpression of the serine/threonine kinase Aurora A (AURKA). Its role in mitotic progression has been extensively characterised, and evidence for new AURKA functions emerges. Here, we reveal that AURKA is located and imported in mitochondria in several human cancer cell lines. Mitochondrial AURKA impacts on two organelle functions: mitochondrial dynamics and energy production. When AURKA is expressed at endogenous levels during interphase, it induces mitochondrial fragmentation independently from RALA. Conversely, AURKA enhances mitochondrial fusion and ATP production when it is over-expressed. We demonstrate that AURKA directly regulates mitochondrial functions and that AURKA over-expression promotes metabolic reprogramming by increasing mitochondrial interconnectivity. Our work paves the way to anti-cancer therapeutics based on the simultaneous targeting of mitochondrial functions and AURKA inhibition.

Autosomal recessive early-onset Parkinson's disease is most often caused by mutations in the genes encoding the cytosolic E3 ubiquitin ligase Parkin and the mitochondrial serine/threonine kinase PINK1. Studies in Drosophila models and mammalian cells have demonstrated that these proteins regulate various aspects of mitochondrial physiology, including organelle transport, dynamics and turnover. How PINK1 and Parkin orchestrate these processes, and whether they always do so within a common pathway remain to be clarified. We have revisited the role of PINK1 and Parkin in mitochondrial dynamics, and explored its relation to the mitochondrial clearance program controlled by these proteins. We show that PINK1 and Parkin promote Drp1-dependent mitochondrial fission by mechanisms that are at least in part independent. Parkin-mediated mitochondrial fragmentation was abolished by treatments interfering with the calcium/calmodulin/calcineurin signaling pathway, suggesting that it requires dephosphorylation of serine 637 of Drp1. Parkinson's disease-causing mutations with differential impact on mitochondrial morphology and organelle degradation demonstrated that the pro-fission effect of Parkin is not required for efficient mitochondrial clearance. In contrast, the use of Förster energy transfer imaging microscopy revealed that Drp1 and Parkin are co-recruited to mitochondria in proximity of PINK1 following mitochondrial depolarization, indicating spatial coordination between these events in mitochondrial degradation. Our results also hint at a major role of the outer mitochondrial adaptor MiD51 in Drp1 recruitment and Parkin-dependent mitophagy. Altogether, our observations provide new insight into the mechanisms underlying the regulation of mitochondrial dynamics by Parkin and its relation to the mitochondrial clearance program mediated by the PINK1/Parkin pathway.