A new Akirin1 gene in turbot (Scophthalmus maximus): molecular cloning, characterization and expression analysis in response to bacterial and viral immunological challenge.

SmAkirin1, a member of the NF-κB signaling pathway, was isolated from turbot by RACE. Its cDNA was 564 bp and encoded a putative protein of 187 amino acids with a predicted molecular mass of 21 kDa and an isoelectric point (pI) of 9.05. Amino acid sequence alignments showed that SmAkirin1 was 91% identical to the Salvelinus alpinus Akirin1 protein ACV49694. Transient expression of SmAkirin1-GFP in the turbot kidney cell line SMKC revealed a nuclear localization of the protein, and a typical NLS signal was found at the N-terminal region of the SmAkirin1 protein. Trans-activation assay in yeast demonstrated that SmAkirin1 has no transcriptional activation. Transcriptional analysis showed that SmAkirin1 was expressed in all of the tissues examined, with the highest expression in the spleen and brain. Real-time quantitative reverse-transcriptase polymerase chain reaction analysis showed that the SmAkirin1 transcript was induced by bacterial and viral infection.