The role of neuromedin U during inflammatory response in the common carp.

In the current study, we cloned and characterized the neuromedin U (NMU) gene from the common carp Cyprinus carpio L., and identified its participation in immune responses in the teleost. Five isoforms of the preproNMU genes were generated by alternative splicing and isolated from carp. The longest form of the carp preproNMU1 (isoform 1) cDNA was composed of 803 bp, and contained an 18 bp 5'-UTR, a 212 bp 3'-UTR and a 573 bp open reading frame, which translates into a peptide comprising 190 amino acid (aa) residues. The remaining carp preproNMU isoforms were composed of 175 (preproNMU2), 158 (preproNMU3), 150 (preproNMU4) and 133 (preproNMU5) aa residues. Isoforms 1-3 contained four processing signals (KR or RR), while isoforms 4 and 5 contained only two processing signals. High homology was demonstrated among fish and other vertebral NMU at the biologically active C-terminal region (aa position 175-182). Carp preproNMU transcript variants were identified in various tissues, and the expression pattern has been shown to change depending on feeding status. Moreover, it was shown that the expression of preproNMU3 and preproNMU5 was increased following treatment with bacterial or viral mimics. Finally, we investigated the functional aspect of carp NMU using a synthetic NMU peptide. The peptide was found to increase the expression of inflammation-related cytokine genes in intestinal cells within 1 h of treatment. In addition, the activation of phagocytic cells was also stimulated by the NMU peptide. The discovery of NMU in carp allows for a further understanding of immune regulation by biologically active substances.

Characterization and expression analysis of type I interferon in common carp Cyprinus carpio L.

The type I interferon (I-IFN) gene has recently been cloned and sequenced in the common carp species Cyprinus carpio L. Carp I-IFN cDNA is composed of 675 base pairs and is translated into a protein of 186 amino acid residues. The carp I-IFN encodes a predicted signal peptide of 23 amino acid residues and contains the I-IFN family signature His(140)-Trp(158). Analysis of the homology between carp I-IFN and other known I-IFN and type II interferon (II-IFN) family members has revealed significant similarities to grass carp I-IFN. Phylogenetic analysis demonstrated that carp I-IFN clusters with I-IFN in teleosts, away from the other II-IFN family members. In addition, the gene structure for carp I-IFN is composed of 5 exons and 4 introns, a composition that is similar to that of the teleost I-IFN gene. RT-PCR analysis did not reveal gene expression in un-stimulated tissues including intestine, liver, gill, head kidney, muscle, spleen, mid-kidney and skin. However, I-IFN expression levels increased following stimulation with imiquimod in the head kidney cells. Furthermore, recombinant carp I-IFN protein (mature form) produced via the cell-free protein synthesis system stimulated the expression of the interferon-inducible Mx gene in the head kidney cells.