Molecular delineation of three chemokines from big belly seahorse (Hipocampus abdominalis) and their putative role in the regulation inflammatory responses  

Chemokines are a family of chemotactic cytokines that regulate leukocyte migration. They are classified into four groups namely, CXC, CC, C, and CX3C, based on the formation of disulfide-bridge. Among these, CXC chemokines are identified as the largest group of chemokines in human. In this study, we identified and functionally characterized a homolog of one CXC chemokine and two CC chemokines from Hippocampus abdominalis and designated them as HaCXCL, HaCCa and HaCCb, respectively. Complete coding sequences (CDS) of seahorse HaCXCL, HaCCa and HaCCb were comprised of 342, 276, and 333 base pairs (bp), respectively, which encode polypeptides of 113, 91, and 110 amino acids, respectively, with molecular masses of ~9 -13 kDa. The CXC and CC family specific small cytokine domain (SCY) were identified from the mature peptide region, which comprised of conserved cysteine residues. The recombinant proteins of each chemokine strongly induced the NO production on macrophage cells (RAW 264.7 cells), and showed the chemotactic effect on flounder peripheral blood leukocytes (Fig.1). Tissue specific profiling of HaCXCL, HaCCLa and HaCCLb showed a ubiquitous expression pattern in all examined tissues with the high abundance in spleen, gill and skin, respectively. Up-regulated pattern of mRNA expression was observed in blood and kidney tissues after immune stimulation by live bacteria (Streptococcus iniaea and Edwardsiella tarda) and mitogens (LPS and poly I:C) suggesting their important roles in host immune defense against microbial infection.