Posttranslational processing of hepcidin in human hepatocytes is mediated by the prohormone convertase furin.
Hepcidin is encoded as an 84 amino acid prepropeptide containing a typical N-terminal 24 amino acid endoplasmic reticulum targeting signal sequence, and a 35 amino acid proregion (pro) with a consensus furin cleavage site immediately followed by the C-terminal 25 amino acid bioactive iron-regulatory hormone (mature peptide). We performed pulse-chase studies of posttranslational processing of hepcidin in human hepatoma HepG2 cells and in primary human hepatocytes induced with bone morphogenic protein (BMP-9). In some experiments, the cells were treated with the furin protease inhibitor decanoyl-Arg-Val-Lys-Arg-chloromethylketone (CMK) or furin siRNA. In the absence of furin inhibitor, hepcidin was found to be processed in less than 1 h and secreted as a 3 kDa form reactive with anti-mature but not anti-pro antibody. In the presence of furin inhibitors or furin siRNA, a 6 kDa form reactive with both anti-pro and anti-mature antibody was rapidly secreted into the medium. Processing was not affected by inhibitors of the hypoxia inducible factor (HIF) pathway, or by treatment with 30 microM holo- or apo-transferrin. In conclusion, the hepatic prohormone convertase furin mediates the posttranslational processing of hepcidin. The proteolytic cleavage of prohepcidin to hepcidin is not regulated by iron-transferrin or the HIF pathway.
Valore
Erika V
EV
Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1690, USA.
Ganz
Tomas
T
D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D045683:Furin / Q000378:metabolism*; D022781:Hepatocytes / Q000378:metabolism*; D064451:Hepcidins; D006801:Humans; D051793:Hypoxia-Inducible Factor 1; D010446:Peptide Fragments; D043484:Proprotein Convertases / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D014168:Transferrin
D023181:Antimicrobial Cationic Peptides; C578702:HAMP protein, human; D064451:Hepcidins; D051793:Hypoxia-Inducible Factor 1; D010446:Peptide Fragments; D014168:Transferrin; D043484:Proprotein Convertases; D045683:Furin