cDNA microarray analysis of interleukin-1β-induced Japanese flounder Paralichthys olivaceus kidney cells

Interleukin-1β (IL-1β) cDNA of Japanese flounder was found to consist of 1329 bp, encoded 247 amino acid residues. Among the fish IL-1β in the databases, the one with the highest identity of Japanese flounder IL-1β was that of seabass (62% identity). The expression of IL-1β was induced by treatment with concanavalin A (ConA)/phorbol myristate acetate (PMA) and lipopolysaccharide. The copy number of IL-1β mRNA was increased 30-fold after stimulation with ConA/PMA. Of 871 cDNA on a microarray, 93 genes (10.7%) were up-regulated or down-regulated by IL-1β at 1, 3 and 7 days post-injection. The induced gene expression was highest on day 1 followed by day 3 and day 7. A total of 7% of known and 3.7% of unknown genes of the 871 tested genes were differentially expressed. Of the genes tested, 7.4% were up-regulated and 3.3% were down-regulated. Cytokine genes such as tumor necrosis factor, granulocyte colony stimulating factor and chemokine receptor A were induced in response to IL-1β. Cell surface antigens such as IgM, MHC class I and CD20 receptor were up-regulated. Signal transduction genes such as Toll-like receptor 1 and SH3P2 were also up-regulated. The glucocorticoid receptor and cAMP early repressor were down-regulated in our microarray analysis.