Urinary copper elevation in a mouse model of Wilson's disease is a regulated process to specifically decrease the hepatic copper load

Lawrence W. Gray, Fangyu Peng, Shannon A. Molloy, Venkata S. Pendyala, Abigael Muchenditsi, Otto Muzik, Jaekwon Lee, Jack H. Kaplan, Svetlana Lutsenko

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Abstract

Body copper homeostasis is regulated by the liver, which removes excess copper via bile. In Wilson's disease (WD), this function is disrupted due to inactivation of the copper transporter ATP7B resulting in hepatic copper overload. High urinary copper is a diagnostic feature of WD linked to liver malfunction; the mechanism behind urinary copper elevation is not fully understood. Using Positron Emission Tomography-Computed Tomography (PET-CT) imaging of live Atp7b-/- mice at different stages of disease, a longitudinal metal analysis, and characterization of copper-binding molecules, we show that urinary copper elevation is a specific regulatory process mediated by distinct molecules. PET-CT and atomic absorption spectroscopy directly demonstrate an age-dependent decrease in the capacity of Atp7b-/- livers to accumulate copper, concomitant with an increase in urinary copper. This reciprocal relationship is specific for copper, indicating that cell necrosis is not the primary cause for the initial phase of metal elevation in the urine. Instead, the urinary copper increase is associated with the down-regulation of the copper-transporter Ctr1 in the liver and appearance of a 2 kDa Small Copper Carrier, SCC, in the urine. SCC is also elevated in the urine of the liver-specific Ctr1-/- knockouts, which have normal ATP7B function, suggesting that SCC is a normal metabolite carrying copper in the serum. In agreement with this hypothesis, partially purified SCC-Cu competes with free copper for uptake by Ctr1. Thus, hepatic down-regulation of Ctr1 allows switching to an SCC-mediated removal of copper via kidney when liver function is impaired. These results demonstrate that the body regulates copper export through more than one mechanism; better understanding of urinary copper excretion may contribute to an improved diagnosis and monitoring of WD.

Original languageEnglish (US)
Article numbere38327
JournalPloS one
Volume7
Issue number6
DOIs
StatePublished - Jun 22 2012

Fingerprint

hepatolenticular degeneration
Hepatolenticular Degeneration
Copper
animal models
copper
liver
Liver
positron-emission tomography
Positron emission tomography
urine
Urine
computed tomography
Tomography
transporters
Down-Regulation
Metals
Metal analysis
metals

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)
  • General

Cite this

Gray, L. W., Peng, F., Molloy, S. A., Pendyala, V. S., Muchenditsi, A., Muzik, O., ... Lutsenko, S. (2012). Urinary copper elevation in a mouse model of Wilson's disease is a regulated process to specifically decrease the hepatic copper load. PloS one, 7(6), [e38327]. https://doi.org/10.1371/journal.pone.0038327

Urinary copper elevation in a mouse model of Wilson's disease is a regulated process to specifically decrease the hepatic copper load. / Gray, Lawrence W.; Peng, Fangyu; Molloy, Shannon A.; Pendyala, Venkata S.; Muchenditsi, Abigael; Muzik, Otto; Lee, Jaekwon; Kaplan, Jack H.; Lutsenko, Svetlana.

In: PloS one, Vol. 7, No. 6, e38327, 22.06.2012.

Research output: Contribution to journalArticle

Gray, LW, Peng, F, Molloy, SA, Pendyala, VS, Muchenditsi, A, Muzik, O, Lee, J, Kaplan, JH & Lutsenko, S 2012, 'Urinary copper elevation in a mouse model of Wilson's disease is a regulated process to specifically decrease the hepatic copper load', PloS one, vol. 7, no. 6, e38327. https://doi.org/10.1371/journal.pone.0038327
Gray, Lawrence W. ; Peng, Fangyu ; Molloy, Shannon A. ; Pendyala, Venkata S. ; Muchenditsi, Abigael ; Muzik, Otto ; Lee, Jaekwon ; Kaplan, Jack H. ; Lutsenko, Svetlana. / Urinary copper elevation in a mouse model of Wilson's disease is a regulated process to specifically decrease the hepatic copper load. In: PloS one. 2012 ; Vol. 7, No. 6.
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