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Gastroenterology. 2007 Jan;132(1):294-300. Epub 2006 Oct 17.

STAT3 is required for IL-6-gp130-dependent activation of hepcidin in vivo.

Author information

1
Center for Hemochromatosis, Department of Internal Medicine, University of Modena and Reggio Emilia, Policlinico Via del Pozzo 71, 41100 Modena, Italy.

Erratum in

  • Gastroenterology. 2007 Mar;132(3):1208.

Abstract

BACKGROUND & AIMS:

Hepcidin is a peptide hormone that is central to the regulation of iron homeostasis. In response to interleukin 6 (IL-6), hepatocytes produce hepcidin that decreases iron release/transfer from enterocytes and macrophages and causes hypoferremia. To clarify the molecular pathways involved in hepcidin activation by IL-6, we used different mice strains in which the main IL-6/gp130 signaling pathways have been genetically disrupted.

METHODS:

We generated mice with hepatocyte-specific deletion of the IL-6 signal-transducing gp130 receptor (alfpgp130 (LoxP/LoxP)), with a gp130 receptor lacking the essential region for STAT1 and -3 activation (alfpCre gp130(DeltaSTAT/LoxP)) or mice expressing a gp130 allele lacking the essential tyrosine for RAS-MAPK activation (alfpCregp130(Y757F/LoxP)). We studied gp130-dependent pathways and hepcidin mRNA expression by Western blot, reverse-transcription polymerase chain reaction, and Northern blot in vivo and ex vivo.

RESULTS:

IL-6 stimulated phospho STAT3, serum amyloid A (SAA), and suppressor of cytokine signaling 3 (SOCS3) expression in livers of wild-type and alfpCregp130(Y757F/LoxP) mice, whereas this response was blocked in alfpCre gp130(LoxP/LoxP) and alfpCre gp130(DeltaSTAT/LoxP) mice. In wild-type and alfpCregp130(Y757F/LoxP) animals, significantly higher hepcidin mRNA expression was found 3 to 6 hours after IL-6 stimulation. In contrast, no IL-6-dependent regulation of hepcidin mRNA expression was found in alfpgp130 (DeltaSTAT/LoxP) and AlfpCre gp130 (LoxP/LoxP) animals. In primary hepatocytes, higher hepcidin mRNA expression after IL-6 stimulation was only observed when gp130-STAT3-dependent signaling was intact.

CONCLUSIONS:

We have demonstrated that both in vivo and in vitro STAT3 is the key transcription factor responsible for IL-6 activation of hepcidin gene expression in the liver.

PMID:
17241879
DOI:
10.1053/j.gastro.2006.10.018
[Indexed for MEDLINE]

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