The mitochondrial calcium uniporter (MCU ) is an essential protein of the inner mitochondrial membrane that mediates the uptake of calcium into mitochondria of virtually all mammalian tissues, regulating cell metabolism, signaling, and death. MCU-mediated calcium uptake has been shown to play a pathophysiological role in diverse human disease contexts, which qualifies this channel as a druggable target for therapeutic intervention.Here, we present a protocol to perform drug screens to identify effective and specific MCU-targeting inhibitors. The methodology is based on the use of cryopreserved mitochondria that are isolated from a yeast strain engineered to express the human MCU and its essential regulator EMRE together with the luminescence calcium sensor aequorin. Yeast mitochondria with a functionally reconstituted MCU-mediated calcium uptake are then employed as a ready-to-use screening reagent. False discovery rate is further minimized by energizing mitochondria with D-lactate in a mannitol/sucrose-based medium, which provides a mean to discriminate between direct and secondary effects of drugs on mitochondrial calcium uptake. This screening assay is sensitive and robust and can be easily implemented in any laboratory.
Keywords: Aequorin; Calcium; Drug screening; Luminescence assay; Mitochondria; Mitochondrial calcium uniporter; Yeast.