Expression In Fish Of Hepcidin, A Putative Antimicrobial Peptide And Iron Regulatory Hormone

Hepcidin is a small, cationic peptide that was originally identified in mammals as an antimicrobial peptide and later shown to be an important iron regulatory hormone. Highly conserved hepcidin sequences have been identified in numerous fish species and there is evidence that the antimicrobial and iron-regulatory functions are conserved in fish as well. This review describes the expression of hepcidin genes in fish. In fish, hepcidin is primarily expressed in the liver. Expression is up-regulated by exposure to Gram-positive bacteria, Gram-negative bacteria, bacterial components such as lipopolysaccharides (LPS), vaccination with attenuated bacteria, and double-stranded RNA (a viral mimic). Hepcidin expression is also induced in response to excess iron and reduced by hypoxia and anemia. The expression patterns of hepcidin genes in some fish species suggest that the possible iron regulatory and antimicrobial activities may be separated into distinct hepcidin peptides in some fish species.