LAUSR

Abstract Hepcidin (Hepc), as an antimicrobial peptide, plays a vital role in regulating the iron homeostasis and participating in innate immunity. In this study, the open reading frame of Nile tilapia (Oreochromis niloticus) hepcidin mRNA (OnHepc) was amplified, and its tissue distribution and expression pattern in response to bacterial infection and iron overload were characterized. The results showed that the ORF of OnHepc is 273 bp in length and encodes a peptide with 90 amino acids. Hepcidin has a certain degree of conservation among different species. OnHepc is widely expressed in ten tissues of natural Nile tilapia and is most abundant in the liver. The expression of OnHepc was apparently upregulated in liver, spleen, intestine and gills after challenged by S. agalactiae and A. hydrophila. In addition, the OnHepc expression in MO/Mo and hepatocytes was also upregulated after challenged by the above bacteria. On the other hand, the OnHepc transcripts were upregulated in the liver, spleen, intestine and gills after challenged by 1 μM and 10 μM FeCl3 solutions, and the same trends were observed in the MO/Mo and hepatocytes after challenged by ferric ions. Moreover, the OnHepc expression was significantly upregulated after stimulated by (r)OnIL-6 protein, suggesting that inflammatory responses regulate the expression of OnHepc. In summary, the present study shows that OnHepc probably gets involved in against bacterial infection and regulating the iron homeostasis in O. niloticus.