Iron- and inflammation-induced hepcidin gene expression in mice is not mediated by Kupffer cells in vivo.
Hepcidin, a recently discovered iron regulatory peptide, is believed to inhibit the release of iron from absorptive enterocytes and macrophages. Liver hepcidin synthesis is induced in vivo by iron stores and inflammation. The molecular basis of the regulation of hepcidin gene expression by these effectors in hepatocytes is currently unknown, although there is strong evidence that indirect mechanisms are involved. The aims of this study were to gain insight into these mechanisms and to determine to what extent other liver cell types are responsible for transducing the signal by which hepcidin expression is regulated in mouse hepatocytes. For this, we depleted Kupffer cells by injection of liposome-encapsulated clodronate and then studied iron- and inflammation-induced hepcidin gene expression. In addition, we directly evaluated the role of the inflammatory cytokine interleukin 6 (IL-6) by using IL-6-deficient mice. Our results show that iron is able to induce hepcidin gene expression independently of Kupffer cells in the liver and circulating IL-6. In contrast, we show that hepcidin gene induction by inflammation is also independent of Kupffer cells, but involves, at least partly, IL-6. In conclusion, these results show that two independent regulatory pathways control hepcidin gene expression and suggest that hepatocytes play a key role in the regulation of hepcidin gene expression by sensing iron and inflammatory signals.
Lou
Dan-Qing
DQ
Département de Génétique, Développement et Pathologie Moléculaire, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, et Université René Descartes, Faculté de Médecine Cochin-Port Royal, Paris, France.
Lesbordes
Jeanne-Claire
JC
Nicolas
Gaël
G
Viatte
Lydie
L
Bennoun
Myriam
M
Van Rooijen
Nico
N
Kahn
Axel
A
Renia
Laurent
L
Vaulont
Sophie
S
D000818:Animals; D000963:Antimetabolites / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000235:genetics*; D004002:Clodronic Acid / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D006505:Hepatitis / Q000378:metabolism* / Q000503:physiopathology*; D064451:Hepcidins; D015850:Interleukin-6 / Q000235:genetics; D007501:Iron / Q000378:metabolism* / Q000494:pharmacology; D007728:Kupffer Cells / Q000378:metabolism*; D008081:Liposomes / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D015398:Signal Transduction / Q000502:physiology
D000963:Antimetabolites; D023181:Antimicrobial Cationic Peptides; C579599:Hamp protein, mouse; D064451:Hepcidins; D015850:Interleukin-6; D008081:Liposomes; D004002:Clodronic Acid; D007501:Iron