Cloning and tissue-specific expression analysis of hepcidin gene in koi ( Cyprinus carpio )

Objective Our aim is to clone cDNA sequence of hepcidin gene (k-hepc) and find its expression pattern in koi ( Cyprinus carpio ). Methods In this study,the full-length cDNA sequence of hepcidin gene in koi was cloned by RT-PCR and RACE PCR and sequenced. The liver,spleen,kidney,intestine,brain,heart,muscle and gill were obtained 0,4,8,12,24 and 48 h after the koi were challenged with Aeromonas veroii and evaluated by real time PCR to find gene expression of k-hepc. Results The sequence of k-hepc cDNA (GenBank No. KC795559) is 755 bp in length,and ORF is 276 bp long. The deduced amino acid sequence of k-hepc gene consists of 91 amino acids including signal peptide,prodomain and mature peptide. The mature peptide contains 8 cysteines,and is able to form 4 disulfide bonds. The deduced amino acid sequence of k-hepc has 93% similarity to hepcidins of known common carp and 29%-93% similarity to hepcidins of other fish species. Expression of k-hepc is found in all the tissues tested by our lab. The relative expression levels in normal fish showed high basal values in liver and low values in gill. The expression of k-hepc mRNA was significantly increased in the liver and heart but not significantly induced in other tissues after bacterial-challenge. Conclusion The protein encoded by k-hepc is a member of hepcidin family. Expression of k-hepc is mainly affected by intrinsic regulation factors.