Sustained Submicromolar H2O2 Levels Induce Hepcidin via Signal Transducer and Activator of Transcription 3 (STAT3)

• Published in: The Journal of biological chemistry Vol. 287; no. 44; pp. 37472 - 37482
• Main Authors: Millonig, Gunda, Ganzleben, Ingo, Peccerella, Teresa, Casanovas, Guillem, Brodziak-Jarosz, Lidia, Breitkopf-Heinlein, Katja, Dick, Tobias P., Seitz, Helmut-Karl, Muckenthaler, Martina U., Mueller, Sebastian
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 26.10.2012; American Society for Biochemistry and Molecular Biology
• Subjects: Acetylcysteine - pharmacology; Anemia of Chronic Diseases; Antimicrobial Cationic Peptides - genetics; Antimicrobial Cationic Peptides - metabolism; Binding Sites; Bone Morphogenetic Protein 6 - physiology; Cell Line, Tumor; Free Radical Scavengers - pharmacology; Hepatocyte; Hepcidin; Hepcidins; Humans; Hydrogen Peroxide; Hydrogen Peroxide - pharmacology; Inflammation Mediators - pharmacology; Interleukin-6 - physiology; Iron Metabolism; Liver Metabolism; Molecular Bases of Disease; Oxidative Stress; Phosphorylation; Promoter Regions, Genetic; Protein Processing, Post-Translational; Signal Transduction; Signaling; STAT3 Transcription Factor - metabolism; Transcription, Genetic; Up-Regulation; Signaling; Liver Metabolism; Hepatocyte; Iron Metabolism; Oxidative Stress; Anemia of Chronic Diseases; Hydrogen Peroxide; Hepcidin
• ISSN: 0021-9258; 1083-351X; 1083-351X
• DOI: 10.1074/jbc.M112.358911

The peptide hormone hepcidin regulates mammalian iron homeostasis by blocking ferroportin-mediated iron export from macrophages and the duodenum. During inflammation, hepcidin is strongly induced by interleukin 6, eventually leading to the anemia of chronic disease. Here we show that hepatoma cells and primary hepatocytes strongly up-regulate hepcidin when exposed to low concentrations of H2O2 (0.3–6 μm), concentrations that are comparable with levels of H2O2 released by inflammatory cells. In contrast, bolus treatment of H2O2 has no effect at low concentrations and even suppresses hepcidin at concentrations of >50 μm. H2O2 treatment synergistically stimulates hepcidin promoter activity in combination with recombinant interleukin-6 or bone morphogenetic protein-6 and in a manner that requires a functional STAT3-responsive element. The H2O2-mediated hepcidin induction requires STAT3 phosphorylation and is effectively blocked by siRNA-mediated STAT3 silencing, overexpression of SOCS3 (suppressor of cytokine signaling 3), and antioxidants such as N-acetylcysteine. Glycoprotein 130 (gp130) is required for H2O2 responsiveness, and Janus kinase 1 (JAK1) is required for adequate basal signaling, whereas Janus kinase 2 (JAK2) is dispensable upstream of STAT3. Importantly, hepcidin levels are also increased by intracellular H2O2 released from the respiratory chain in the presence of rotenone or antimycin A. Our results suggest a novel mechanism of hepcidin regulation by nanomolar levels of sustained H2O2. Thus, similar to cytokines, H2O2 provides an important regulatory link between inflammation and iron metabolism. Background: Hepcidin, the systemic iron regulator, is induced during inflammation and leads to low circulating and increased intracellular iron levels. Results: (Patho)physiologically relevant H2O2 levels up-regulate hepcidin via STAT3 in cultured liver cells. Conclusion: Intracellular and extracellular H2O2 acts similarly to IL-6 on hepcidin up-regulation and requires a functional STAT3-binding site. Significance: H2O2 is an important link between inflammation and iron metabolism.