Question: What is the connection between furin and hepcidin?

Context:
Hepcidin is mainly produced by the liver as a propeptide and processed by furin into the mature active peptide. 
Implication of the proprotein convertases in iron homeostasis: proprotein convertase 7 sheds human transferrin receptor 1 and furin activates hepcidin.
Analysis of primary hepatocytes from mice lacking furin, PC5, PACE4, or PC7 revealed that hepcidin, which limits iron availability in the circulation, is specifically generated by furin and not by PC7. 
Among the PC family members, only furin activates hepcidin in hepatocytes, and uniquely the full-length membrane-bound PC7 can directly shed hTfR1 by cleavage at Arg100 ↓.
The human hepcidin gene contains three exons that encode a 72-aa precursor (pro-hepcidin) with a characteristic furin cleavage site immediately N-terminal to the 25-aa major hepcidin species found in plasma and urine [3]
Pro-hepcidin is unable to degrade the iron exporter ferroportin unless maturated by a furin-dependent process.
The iron-regulatory peptide hepcidin is synthesized in the liver as an 84-aa pre-pro-hormone maturated by proteolysis through a consensus furin cleavage site to generate the bioactive 25-aa peptide secreted in the circulation. This peptide regulates iron export from enterocytes and macrophages by binding the membrane iron exporter, ferroportin, leading to its degradation. 
Our results demonstrate that pro-hepcidin lacks biological activity, unless fully maturated by a furin-dependent process to yield the bioactive 25-aa peptide.
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). 
In conclusion, the hepatic prohormone convertase furin mediates the posttranslational processing of hepcidin.
In conclusion, the hepatic prohormone convertase furin mediates the posttranslational processing of hepcidin.
Furin in turn may control hepcidin expression.
Regulation of prohepcidin processing and activity by the subtilisin-like proprotein convertases Furin, PC5, PACE4 and PC7.
BACKGROUND/AIMS: The iron-regulatory peptide hepcidin is synthesized in the liver as an 84-aa pre-pro-hormone maturated by proteolysis through a consensus furin cleavage site to generate the bioactive 25-aa peptide secreted in the circulation.
Furin activity was also modulated using furin inhibitor or siRNA-mediated furin mRNA knockdown.RESULTS: We found that pro-hepcidin could fully induce ferroportin degradation, but only when processed by furin to generate the mature hepcidin-25 form.
Furin activity was also modulated using furin inhibitor or siRNA-mediated furin mRNA knockdown.We found that pro-hepcidin could fully induce ferroportin degradation, but only when processed by furin to generate the mature hepcidin-25 form
CONCLUSIONS: These results demonstrate the key role of the convertases Furin, PACE4, PC5 and/or PC7 in the generation and secretion of active hepcidin and suggest that the control of hepcidin processing as a potential therapeutic/diagnostic strategy in hepcidin-related disorders such as haemochromatosis, inflammatory diseases, anaemia and cancer.
BACKGROUND/AIMS: The iron-regulatory peptide hepcidin is synthesized in the liver as an 84-aa pre-pro-hormone maturated by proteolysis through a consensus furin cleavage site to generate the bioactive 25-aa peptide secreted in the circulation. 
CONCLUSIONS: Our results demonstrate that pro-hepcidin lacks biological activity, unless fully maturated by a furin-dependent process to yield the bioactive 25-aa peptide.
The iron-regulatory peptide hepcidin is synthesized in the liver as an 84-aa pre-pro-hormone maturated by proteolysis through a consensus furin cleavage site to generate the bioactive 25-aa peptide secreted in the circulation.
Furin activity was also modulated using furin inhibitor or siRNA-mediated furin mRNA knockdown.We found that pro-hepcidin could fully induce ferroportin degradation, but only when processed by furin to generate the mature hepcidin-25 form.
Furin in turn may control hepcidin expression.
Analysis of primary hepatocytes from mice lacking furin, PC5, PACE4, or PC7 revealed that hepcidin, which limits iron availability in the circulation, is specifically generated by furin and not by PC7.
Furthermore, the mutated version of pro-hepcidin was completely inefficient at degrading ferroportin in macrophages.CONCLUSIONS: Our results demonstrate that pro-hepcidin lacks biological activity, unless fully maturated by a furin-dependent process to yield the bioactive 25-aa peptide.
However, the activity of the pro-peptide on ferroportin degradation has never been addressed.METHODS: To answer this question, we produced recombinant pro-hepcidin, both the wild-type form and a furin cleavage site mutant, and tested their activity on ferroportin levels in macrophagic J774 cells.
Furin in turn may control hepcidin expression..
We found that pro-hepcidin could fully induce ferroportin degradation, but only when processed by furin to generate the mature hepcidin-25 form.
Posttranslational processing of hepcidin in human hepatocytes is mediated by the prohormone convertase furin.
Implication of the proprotein convertases in iron homeostasis: proprotein convertase 7 sheds human transferrin receptor 1 and furin activates hepcidin.
Pro-hepcidin is unable to degrade the iron exporter ferroportin unless maturated by a furin-dependent process.
These results demonstrate the key role of the convertases Furin, PACE4, PC5 and/or PC7 in the generation and secretion of active hepcidin and suggest that the control of hepcidin processing as a potential therapeutic/diagnostic strategy in hepcidin-related disorders such as haemochromatosis, inflammatory diseases, anaemia and cancer..

Answer: The iron-regulatory peptide hepcidin is synthesized in the liver as an 84-aa pre-pro-hormone maturated by proteolysis through a consensus furin cleavage site to generate the bioactive 25-aa peptide secreted in the circulation. The hepatic prohormone convertase furin mediates the posttranslational processing of hepcidin.