Molecular cloning, gene structure and expression of two CC chemokines from Japanese flounder Paralichthys olivaceus

We cloned the cDNA and genes of two different types of CC chemokine from Japanese flounder Paralichthys olivaceus. The genes were designated JFCC1 and JFCC2. The JFCC1 cDNA encoded 91 amino acid residues. The JFCC1 gene has a size of 1.9 kb and consists of three exons and two introns. Two types of JFCC2 mRNA, corresponding to genes designated JFCC2-1 and JFCC2-2, were detected by reverse transcription-polymerase chain reaction in several organs, although fully spliced mRNA was not detected. The sizes of JFCC2-1 and -2 were 1.9 kb and 1.8 kb, respectively. JFCC2-1 consists of three exons and two introns and JFCC2-2 consists of two exons and one intron, although the coding regions of the two genes are identical. Because the JFCC2 gene has uncommon properties and an uncommon expression pattern, we suggest that it is a pseudogene. Southern blot hybridization and the characterization of BAC clones indicated that both the JFCC1 and JFCC2 genes exist as multicopy genes in the Japanese flounder genome. JFCC1 and JFCC2 genes were expressed in several organs including peripheral blood leukocytes (PBL) and kidney. The two forms of JFCC2 mRNA were also encountered in these cells. Expressions of JFCC1 and JFCC2 genes were upregulated after stimulation with concanavalin A/phorbol myristate acetate and lipopolysaccharide, compared with normal PBL.