Posttranslational processing of hepcidin in human hepatocytes is mediated by the prohormone convertase furin

Abstract

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.

Identification of an iron–hepcidin complex

“…On the other hand, Kemna et al recently showed that whereas hepcidin level increases during inflammation and decreases in patients with iron deficiency and thalassaemia major, serum prohepcidin levels displayed no significant difference between all the groups tested [10]. A consensus site for the convertase family of mammalian propeptide-processing enzymes has been identified at Arg59, and furin, a member of this family of pro-protein convertase largely expressed in the liver, has recently been shown to mediate the posttranslational processing of hepcidin [11]. In cell culture, whereas no prohepcidin could be detected in the media under control conditions, inhibition of the furin activity resulted in secretion of the propeptide in the media, indicating the role of furin in the cellular maturation of the active peptide.…”

A Novel Isoform of the Hepatic Antimicrobial Peptide, Hepcidin (Hepc-CB1), from a Deep-Sea Fish, the Spinyjaw Greeneye Chlorophthalmus bicornis (Norman, 1939): Molecular Characterisation and Phylogeny

“…Proteolytic cleavage of the signal peptide and prodomain from the prepropeptide yields the bioactive mature peptide [9,34,35]. Highly conserved cysteine residues in the mature peptide regions form the core domain signature, which serves as the disulphide-bridged back bone of the b-hairpin-like structures.…”

Anemia de las enfermedades crónicas asociada a obesidad: papel de la hepcidina como mediador central

“…La Hpc es procesada a partir del extremo carboxilo terminal en los hepatocitos por la peptidasa señal a prohepcidina 13 . Previo a su secreción, la prohormona convertasa media el procesamiento postraduccional de la Hpc, generando el compuesto bioactivo maduro 14 .…”