Iron suppresses erythropoietin expression via oxidative stress-dependent hypoxia-inducible factor-2 alpha inactivation

Keisuke Oshima, Yasumasa Ikeda, Yuya Horinouchi, Hiroaki Watanabe, Hirofumi Hamano, Yoshitaka Kihira, Seiji Kishi, Yuki Izawa-Ishizawa, Licht Miyamoto, Tasuku Hirayama, Hideko Nagasawa, Keisuke Ishizawa, Koichiro Tsuchiya, Toshiaki Tamaki

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

Abstract

Renal anemia is a major complication in chronic kidney disease (CKD). Iron supplementation, as well as erythropoiesis-stimulating agents, are widely used for treatment of renal anemia. However, excess iron causes oxidative stress via the Fenton reaction, and iron supplementation might damage remnant renal function including erythropoietin (EPO) production in CKD. EPO gene expression was suppressed in mice following direct iron treatment. Hypoxia-inducible factor-2 alpha (HIF-2α), a positive regulator of the EPO gene, was also diminished in the kidney of mice following iron treatment. Anemia-induced increase in renal EPO and HIF-2α expression was inhibited by iron treatment. In in vitro experiments using EPO-producing HepG2 cells, iron stimulation reduced the expression of the EPO gene, as well as HIF-2α. Moreover, iron treatment augmented oxidative stress, and iron-induced reduction of EPO and HIF-2α expression was restored by tempol, an antioxidant compound. HIF-2α interaction with the Epo promoter was inhibited by iron treatment, and was restored by tempol. These findings suggested that iron supplementation reduced EPO gene expression via an oxidative stress-HIF-2α-dependent signaling pathway.

Original languageEnglish
Pages (from-to)555-566
Number of pages12
JournalLaboratory Investigation
Volume97
Issue number5
DOIs
Publication statusPublished - May 1 2017
Externally publishedYes

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Molecular Biology
  • Cell Biology

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