The human cytochrome c oxidase assembly factors SCO1 and SCO2 have regulatory roles in the maintenance of cellular copper homeostasis.
Human SCO1 and SCO2 are metallochaperones that are essential for the assembly of the catalytic core of cytochrome c oxidase (COX). Here we show that they have additional, unexpected roles in cellular copper homeostasis. Mutations in either SCO result in a cellular copper deficiency that is both tissue and allele specific. This phenotype can be dissociated from the defects in COX assembly and is suppressed by overexpression of SCO2, but not SCO1. Overexpression of a SCO1 mutant in control cells in which wild-type SCO1 levels were reduced by shRNA recapitulates the copper-deficiency phenotype in SCO1 patient cells. The copper-deficiency phenotype reflects not a change in high-affinity copper uptake but rather a proportional increase in copper efflux. These results suggest a mitochondrial pathway for the regulation of cellular copper content that involves signaling through SCO1 and SCO2, perhaps by their thiol redox or metal-binding state.
Leary
Scot C
SC
Montreal Neurological Institute, McGill University, Montreal, QC H3A 2B4, Canada; Department of Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada.
Cobine
Paul A
PA
Kaufman
Brett A
BA
Guercin
Guy-Hellen
GH
Mattman
Andre
A
Palaty
Jan
J
Lockitch
Gillian
G
Winge
Dennis R
DR
Rustin
Pierre
P
Horvath
Rita
R
Shoubridge
Eric A
EA
D000483:Alleles; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003300:Copper / Q000172:deficiency / Q000378:metabolism*; D000079923:Copper Transporter 1; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005347:Fibroblasts; D006706:Homeostasis; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D017237:Mitochondrial Encephalomyopathies / Q000235:genetics / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones; D009154:Mutation; D009928:Organ Specificity; D010641:Phenotype; D015398:Signal Transduction
D002352:Carrier Proteins; D027682:Cation Transport Proteins; D000079923:Copper Transporter 1; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; C489345:SCO1 protein, human; C400285:SCO2 protein, human; C490079:SLC31A1 protein, human; D003300:Copper; D003576:Electron Transport Complex IV