High-throughput screen identifies a potent MCU activator boosting cardiac contractile bioenergetics

Mitochondrial Ca2+ uptake through the mitochondrial calcium uniporter complex (MCUc) couples intracellular Ca2+ signaling to energy metabolism and cellular function. Despite its physiological importance, potent and selective pharmacological activators of the MCU complex remain scarce, and existing compounds show modest specificity. Here, we screened 1,280 bioactive compounds and identified CGP7930 as a potent activator of mitochondrial Ca2+ uptake. Mechanistically, the compound required MICU1, but not MICU2, to exert its effects. Molecular docking, non-covalent interaction analysis, and site-directed mutagenesis identified Gln304 and Val307 in MICU1 as critical determinants of compound activity. In addition to directly stimulating MCU activity, CGP7930 increased mitochondria-endoplasmic reticulum contact sites, suggesting an additional mechanism to facilitate inter-organellar Ca2+ transfer. CGP7930 promoted Ca2+-dependent activation of mitochondrial energy metabolism in cardiomyocytes and boosted the contractile performance of the mice hearts. This effect was MCU-dependent, as hearts from MCU KO mice failed to increase the ventricular contraction force upon CGP7930 perfusion. Molecular docking, non-covalent interaction analysis, and site-directed mutagenesis identified Gln304 and Val307 in MICU1 as critical determinants of compound activity.