Channel catfish hepcidin expression in infection and anemia.
Hepcidin, originally identified as a 25 amino acid antimicrobial peptide made in the liver, is a key regulator of iron balance and recycling in humans and mice. Closely related hepcidin genes and peptides have also been identified in a number of fish species and in teleosts are thought to function as endogenous antibiotics involved in host defense against infection. Here we report the transcriptional regulation of hepcidin expression by infection and anemia in the channel catfish. Changes in hepcidin expression in catfish challenged with Edwardsiella ictaluri and in fish affected by channel catfish anemia (CCA) were measured by real time quantitative PCR. Hepcidin transcript levels in the livers were increased 4, 19, and 22-fold at 4, 24, and 48h following bacterial challenge, respectively. However, augmented hepcidin expression in the intestine and olfactory sac was detected only at 48h post-infection. Hepcidin transcript levels in the livers of catfish affected by CCA were less than 14% of that present in healthy counterparts. Hepatic hepcidin transcript levels correlated significantly with serum iron concentrations (r=0.54, p<0.05) and with the percent saturation of transferrin (r=0.63, p<0.05). Similar to mammalian hepcidins, channel catfish hepcidin is an iron-responsive gene and may also play important roles in innate host defense to infection and in iron homeostasis. Mammalian hepcidins may have evolved from an antimicrobial peptide and its structure and transcriptional regulatory mechanisms have been conserved throughout vertebrate evolution.
Hu
Xueyou
X
Department of Anatomy, Physiology and Pharmacology, 212 Greene Hall, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA.
Camus
Alvin C
AC
Aono
Shelly
S
Morrison
Edward E
EE
Dennis
John
J
Nusbaum
Kenneth E
KE
Judd
Robert L
RL
Shi
Jishu
J
D000595:Amino Acid Sequence; D000740:Anemia / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism*; D001483:Base Sequence; D020610:Edwardsiella ictaluri; D004756:Enterobacteriaceae Infections / Q000235:genetics / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D005393:Fish Diseases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D005786:Gene Expression Regulation; D064451:Hepcidins; D007059:Ictaluridae; D007501:Iron / Q000097:blood; D008099:Liver / Q000378:metabolism*; D008969:Molecular Sequence Data; D009928:Organ Specificity; D016133:Polymerase Chain Reaction; D013045:Species Specificity
D023181:Antimicrobial Cationic Peptides; C578702:HAMP protein, human; C579599:Hamp protein, mouse; D064451:Hepcidins; D007501:Iron