RESUMO
Copper is an essential cofactor of cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial respiratory chain. Inherited loss-of-function mutations in several genes encoding proteins required for copper delivery to CcO result in diminished CcO activity and severe pathologic conditions in affected infants. Copper supplementation restores CcO function in patient cells with mutations in two of these genes, COA6 and SCO2, suggesting a potential therapeutic approach. However, direct copper supplementation has not been therapeutically effective in human patients, underscoring the need to identify highly efficient copper transporting pharmacological agents. By using a candidate-based approach, we identified an investigational anticancer drug, elesclomol (ES), that rescues respiratory defects of COA6-deficient yeast cells by increasing mitochondrial copper content and restoring CcO activity. ES also rescues respiratory defects in other yeast mutants of copper metabolism, suggesting a broader applicability. Low nanomolar concentrations of ES reinstate copper-containing subunits of CcO in a zebrafish model of copper deficiency and in a series of copper-deficient mammalian cells, including those derived from a patient with SCO2 mutations. These findings reveal that ES can restore intracellular copper homeostasis by mimicking the function of missing transporters and chaperones of copper, and may have potential in treating human disorders of copper metabolism.
Assuntos
Antineoplásicos/farmacologia , Cobre/deficiência , Drogas em Investigação/farmacologia , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Hidrazinas/farmacologia , Mitocôndrias/efeitos dos fármacos , Animais , Antineoplásicos/uso terapêutico , Transporte Biológico/genética , Proteínas de Transporte/genética , Linhagem Celular , Coenzimas/deficiência , Cobre/uso terapêutico , Transportador de Cobre 1 , Suplementos Nutricionais , Modelos Animais de Doenças , Reposicionamento de Medicamentos , Drogas em Investigação/uso terapêutico , Fibroblastos , Humanos , Hidrazinas/uso terapêutico , Proteínas de Membrana Transportadoras/genética , Erros Inatos do Metabolismo/tratamento farmacológico , Erros Inatos do Metabolismo/genética , Erros Inatos do Metabolismo/metabolismo , Mitocôndrias/metabolismo , Proteínas Mitocondriais/genética , Chaperonas Moleculares , Mutagênese Sítio-Dirigida , Mutação , Ratos , Saccharomyces cerevisiae , Peixe-Zebra , Proteínas de Peixe-Zebra/genéticaRESUMO
Mitochondrial Ca(2+) Uniporter (MCU)-dependent mitochondrial Ca(2+) uptake is the primary mechanism for increasing matrix Ca(2+) in most cell types. However, a limited understanding of the MCU complex assembly impedes the comprehension of the precise mechanisms underlying MCU activity. Here, we report that mouse cardiomyocytes and endothelial cells lacking MCU regulator 1 (MCUR1) have severely impaired [Ca(2+)]m uptake and IMCU current. MCUR1 binds to MCU and EMRE and function as a scaffold factor. Our protein binding analyses identified the minimal, highly conserved regions of coiled-coil domain of both MCU and MCUR1 that are necessary for heterooligomeric complex formation. Loss of MCUR1 perturbed MCU heterooligomeric complex and functions as a scaffold factor for the assembly of MCU complex. Vascular endothelial deletion of MCU and MCUR1 impaired mitochondrial bioenergetics, cell proliferation, and migration but elicited autophagy. These studies establish the existence of a MCU complex that assembles at the mitochondrial integral membrane and regulates Ca(2+)-dependent mitochondrial metabolism.