Cellular copper levels determine the phenotype of the Arg875 variant of ATP7B/Wilson disease protein

Arnab Gupta, Ashima Bhattacharjee, Oleg Y. Dmitriev, Sergiy Nokhrin, Lelita Braiterman, Ann L. Hubbard, Svetlana Lutsenko

Research output: Contribution to journalArticle

Abstract

In human disorders, the genotype-phenotype relationships are often complex and influenced by genetic and/or environmental factors. Wilson disease (WD) is a monogenic disorder caused by mutations in the copper-transporting P-type ATPase ATP7B. WD shows significant phenotypic diversity even in patients carrying identical mutations; the basis for such diverse manifestations is unknown. We demonstrate that the 2623A/G polymorphism (producing the Gly875→ Arg substitution in the A-domain of ATP7B) drastically alters the intracellular properties of ATP7B, whereas copper reverses the effects. Under basal conditions, the common Gly875 variant of ATP7B is targeted to the trans-Golgi network (TGN) and transports copper into the TGN lumen. In contrast, the Arg875 variant is located in the endoplasmic reticulum (ER) and does not deliver copper to the TGN. Elevated copper corrects the ATP7B-Arg 875 phenotype. Addition of only 0.5-5 μM copper triggers the exit of ATP7B-Arg875 from the ER and restores copper delivery to the TGN. Analysis of the recombinant A-domains by NMR suggests that the ER retention of ATP7B-Arg875 is attributable to increased unfolding of the Arg 875-containing A-domain. Copper is not required for the folding of ATP7B-Arg875 during biosynthesis, but it stabilizes protein and stimulates its activity. A chemotherapeutical drug, cisplatin, that mimics a copper-bound state of ATP7B also corrects the "disease-like" phenotype of ATP7B-Arg875 and promotes its TGN targeting and transport function.We conclude that in populations harboring the Arg875 polymorphism, the levels of bioavailable copper may play a vital role in the manifestations of WD.

Original languageEnglish (US)
Pages (from-to)5390-5395
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Volume108
Issue number13
DOIs
StatePublished - Mar 29 2011

Keywords

  • Cisplatin
  • Phenotypic variability
  • Trafficking

ASJC Scopus subject areas

  • General

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