Identification of novel interleukin 1 beta family genes in Japanese flounder Paralichthys olivaceus

Gene in the interleukin 1 family plays a central role in the regulation of immune and inflammatory responses. Here, we describe two novel IL-1-like gene in Japanese flounder Paralichthys olivaceus (jfIL1-L1 and jfIL1-L2). jfIL1β-L1 was homologous to Nile Tilapia IL-1β-like gene and Arctic char IL-1, and jfIL1β-L2 showed homology to hypothetical protein LOC100699119 of Nile Tilapia and rainbow trout Oncorhynchus mykiss IL-1 receptor agonist (RA). The deduced amino acids sequences of these IL-1β-like genes showed very low identities to the Japanese flounder IL-1 (jfIL-1). Phylogenetic analysis confirmed that jfIL1β-L1 and -L2 were distinct from jfIL-1. The gene encoding the predicted ORF of jfIL1β-L1 and -L2 is divided into 6 exons and 7 exons, respectively. Transcripts of jfIL1β-L1 were detected in gills, intestine, kidney and spleen, and those of jfIL1β-L2 were detected in gills, intestine and spleen. The mRNA levels of jfIL1β-L1 and -L2 were not effect or slightly decreased by treatment with LPS and the formalin-killed cells of Edwardsiella tarda whilst mRNA levels of jfIL1β were significantly increased in the kidney and spleen at 6 h by these treatments.