Identification and expression analysis of hepcidin-like cDNAs from pigeon (Columba livia)

Hepcidin is a cysteine-rich, dual-function peptide with antimicrobial activity that plays a crucial role in iron homeostasis. Here, we have identified two hepcidin-like cDNA sequences from pigeon, Columba livia. The two cDNAs consist of 295 and 380 nucleotides, respectively, and were named HP1 and HP2. Sequence alignment showed that the homology between pigeon and mammals or amphibians is higher than that of pigeon and fishes. Semi-quantitative RT-PCR analysis suggested that HP1 transcripts are highly abundant in liver, abundant in spleen, less abundant in kidney and muscle, and undetectable in brain and intestine. However, HP2 are strongly expressed in the liver, spleen, kidney and muscle, weakly in the intestine, and not in the brain. After pigeon were submitted either to lipopolysaccharide (LPS) infection or iron-dextran stimulation, the hepcidin transcript levels were analyzed by a comparative RT-PCR. The results revealed that the expression of hepatic HP1 dramatically increased at 6 h post-infection of LPS injection, then gradually declined to normal levels. HP1 mRNA in the liver was 4.5-5-fold increase compared with the control animals after one week in iron-dextran injection pigeons. Interestingly, liver HP2 expression was only significant increase in the LPS infection pigeons, and not statistical change in iron-dextran stimulation ones. All these results indicate that the two hepcidins-like may have different functions in pigeon.