Ca2+ flux across the mitochondrial inner membrane regulates bioenergetics, cytoplasmic Ca2+ signals and activation of cell death pathways1,2,3,4,5,6,7,8,9,10,11. Mitochondrial Ca2+ uptake occurs at regions of close apposition with intracellular Ca2+ release sites12,13,14, driven by the inner membrane voltage generated by oxidative phosphorylation and mediated by a Ca2+ selective ion channel (MiCa; ref. 15) called the uniporter16,17,18 whose complete molecular identity remains unknown. Mitochondrial calcium uniporter (MCU) was recently identified as the likely ion-conducting pore19,20. In addition, MICU1 was identified as a mitochondrial regulator of uniporter-mediated Ca2+ uptake in HeLa cells21,22. Here we identified CCDC90A, hereafter referred to as MCUR1 (mitochondrial calcium uniporter regulator 1), an integral membrane protein required for MCU-dependent mitochondrial Ca2+ uptake. MCUR1 binds to MCU and regulates ruthenium-red-sensitive MCU-dependent Ca2+ uptake. MCUR1 knockdown does not alter MCU localization, but abrogates Ca2+ uptake by energized mitochondria in intact and permeabilized cells. Ablation of MCUR1 disrupts oxidative phosphorylation, lowers cellular ATP and activates AMP kinase-dependent pro-survival autophagy. Thus, MCUR1 is a critical component of a mitochondrial uniporter channel complex required for mitochondrial Ca2+ uptake and maintenance of normal cellular bioenergetics.
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This work was supported by the National Institutes of Health grants R01 HL086699, HL086699-01A2S1 and 1S10RR027327-01 to M.M., and GM56328 to J.K.F. C.C. was supported by the Fondo Nacional de Desarrollo Cientifico y Tecnologico (FONDECYT) grant #1120443 and an award from the American Heart Association.
The authors declare no competing financial interests.
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Mallilankaraman, K., Cárdenas, C., Doonan, P. et al. MCUR1 is an essential component of mitochondrial Ca2+ uptake that regulates cellular metabolism. Nat Cell Biol 14, 1336–1343 (2012). https://doi.org/10.1038/ncb2622
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