title: Distinct Wilson's disease mutations in ATP7B are associated with enhanced binding to COMMD1 and reduced stability of ATP7B.
abstract: OBJECTIVE
  Wilson's disease (WD) is characterized by hepatic copper overload and caused by mutations in the gene encoding the copper-transporting P-type adenosine triphosphatase (ATPase) ATP7B. ATP7B interacts with COMMD1, a protein that is deleted in Bedlington terriers with hereditary copper toxicosis. Here we characterized the implications of the interaction between COMMD1 and ATP7B in relation to the pathogenesis of WD.
  
  
  METHODS
  Glutathione-S-transferase pull-down experiments, co-immunoprecipitations, immunofluorescence microscopy, site-directed mutagenesis, and biosynthetic labeling experiments were performed to characterize the interaction between COMMD1 and ATP7B and the effects of WD causing mutations.
  
  
  RESULTS
  COMMD1 specifically interacted with the amino-terminal region of ATP7B. This interaction was independent of intracellular copper levels and of the expression of the copper chaperone ATOX1. Four WD patient-derived mutations in this region of ATP7B significantly increased its binding to COMMD1. Two of these mutations also resulted in mislocalization and increased degradation rate of ATP7B. Although COMMD1 did not affect copper-induced trafficking of ATP7B, it markedly decreased the stability of newly synthesized ATP7B.
  
  
  CONCLUSIONS
  Our data implicate COMMD1 in the pathogenesis of WD and indicate that COMMD1 exerts its regulatory role in copper homeostasis through the regulation of ATP7B stability.
authors.affiliation: Laboratory of Metabolic and Endocrine Diseases, Division of Biomedical Genetics, Department of Medical Genetics, University Medical Center, Utrecht, the Netherlands.
authors.forename: Prim
authors.initials: P
authors.lastname: de Bie
authors.forename: Bart
authors.initials: B
authors.lastname: van de Sluis
authors.forename: Ezra
authors.initials: E
authors.lastname: Burstein
authors.forename: Peter V E
authors.initials: PV
authors.lastname: van de Berghe
authors.forename: Patricia
authors.initials: P
authors.lastname: Muller
authors.forename: Ruud
authors.initials: R
authors.lastname: Berger
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Gitlin
authors.forename: Cisca
authors.initials: C
authors.lastname: Wijmenga
authors.forename: Leo W J
authors.initials: LW
authors.lastname: Klomp
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D027682:Cation Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D003300:Copper / Q000378:metabolism*; D000079922:Copper Transport Proteins; D000073840:Copper-Transporting ATPases; D004721:Endoplasmic Reticulum / Q000378:metabolism; D020022:Genetic Predisposition to Disease; D022781:Hepatocytes / Q000201:enzymology / Q000378:metabolism*; D006527:Hepatolenticular Degeneration / Q000235:genetics / Q000378:metabolism*; D006706:Homeostasis; D006801:Humans; D056511:Metallochaperones; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010447:Peptide Hydrolases / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: C474500:ATOX1 protein, human; D048868:Adaptor Proteins, Signal Transducing; C480519:COMMD1 protein, human; D002352:Carrier Proteins; D027682:Cation Transport Proteins; D000079922:Copper Transport Proteins; D056511:Metallochaperones; D018832:Molecular Chaperones; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D003300:Copper; D010447:Peptide Hydrolases; D000251:Adenosine Triphosphatases; C000612464:ATP7B protein, human; D000073840:Copper-Transporting ATPases