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Hereditary hemochromatosis disrupts uric acid homeostasis and causes hyperuricemia via altered expression/activity of xanthine oxidase and ABCG2

Hereditary hemochromatosis (HH) is mostly caused by mutations in the iron-regulatory gene HFE. The disease is associated with iron overload, resulting in liver cirrhosis/cancer, cardiomegaly, kidney dysfunction, diabetes, and arthritis. Fe(2+)-induced oxidative damage is suspected in the etiology of...

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Detalles Bibliográficos
Autores principales: Ristic, Bojana, Sivaprakasam, Sathish, Narayanan, Monisha, Ganapathy, Vadivel
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Portland Press Ltd. 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7200644/
https://www.ncbi.nlm.nih.gov/pubmed/32239172
http://dx.doi.org/10.1042/BCJ20190873
Descripción
Sumario:Hereditary hemochromatosis (HH) is mostly caused by mutations in the iron-regulatory gene HFE. The disease is associated with iron overload, resulting in liver cirrhosis/cancer, cardiomegaly, kidney dysfunction, diabetes, and arthritis. Fe(2+)-induced oxidative damage is suspected in the etiology of these symptoms. Here we examined, using Hfe(−/−) mice, whether disruption of uric acid (UA) homeostasis plays any role in HH-associated arthritis. We detected elevated levels of UA in serum and intestine in Hfe(−/−) mice compared with controls. Though the expression of xanthine oxidase, which generates UA, was not different in liver and intestine between wild type and Hfe(−/−) mice, the enzymatic activity was higher in Hfe(−/−) mice. We then examined various transporters involved in UA absorption/excretion. Glut9 expression did not change; however, there was an increase in Mrp4 and a decrease in Abcg2 in Hfe(−/−) mice. As ABCG2 mediates intestinal excretion of UA and mutations in ABCG2 cause hyperuricemia, we examined the potential connection between iron and ABCG2. We found p53-responsive elements in hABCG2 promoter and confirmed with chromatin immunoprecipitation that p53 binds to this promoter. p53 protein was reduced in Hfe(−/−) mouse intestine. p53 is a heme-binding protein and p53-heme complex is subjected to proteasomal degradation. We conclude that iron/heme overload in HH increases xanthine oxidase activity and also promotes p53 degradation resulting in decreased ABCG2 expression. As a result, systemic UA production is increased and intestinal excretion of UA via ABCG2 is decreased, causing serum and tissue accumulation of UA, a potential factor in the etiology of HH-associated arthritis.