Molecular characterization and gene expression of a CXC chemokine gene from Japanese flounder Paralichthys olivaceus

Chemokines are small, secreted cytokine peptides that have the ability to recruit a wide range of immune cells to sites of infection and disease. A novel CXC chemokine was obtained from Japanese flounder Paralichthys olivaceus. This chemokine cDNA contains an open reading frame of 333 nucleotides encoding 111 amino acid residues containing four conserved cysteine residues. The gene is composed of four exons and three introns as are those of mammalian and fish CXC chemokines. Results of homology and phylogenetic analysis revealed that the Japanese flounder CXC chemokine is closest to CXCL13 subgroup. The gene was expressed in immune-related organs, including head kidney, trunk kidney, spleen and peripheral blood leukocytes (PBLs). Japanese flounder CXC chemokine gene expression was observed at 3 and 6 h after induction by LPS, but not at 3 and 6 h after induction by poly I:C. These results suggest that the Japanese flounder CXC chemokine is probably associated with inflammatory as well as homeostatic functions.