Cloning and their roles in NF-κB, IFN-β, and AP-1 signaling pathways of AKT1 and AKT2 genes of largemouth bass (Micropterus salmoides).

Abstract

To elucidate the regulatory role of the AKT gene (Protein Kinase B) in the NF-κB, IFN and AP-1 signalling pathways in largemouth bass, the open reading frame (ORF) sequences of the AKT1 and AKT2 genes were isolated from largemouth bass (Micropterus salmoides). AKT1 and AKT2 possessed a conserved Pleckstrin homology (PH) domain, a catalytic serine/threonine kinase domain (STKc), and a specific serine/threonine kinase family domain (STKX). AKT1 was most highly expressed in the spleen, whereas AKT2 showed the highest expression in the blood. Infection with N. seriolae, Poly (I:C), and LMBV significantly induced the expression of AKT1 and AKT2 in largemouth bass. Overexpression of AKT1 and AKT2 did not significantly increased the NF-κB promoter activity; however, significantly activated the AP-1 and IFN-β promoters. Subcellular localisation analysis showed that AKT1 was distributed in both the cytoplasm and nucleus, whereas AKT2 was predominantly localised in the cytoplasm, with weak nuclear signals. Pull-down analysis revealed no interaction between AKT-IP or AKT-IP-like proteins and AKT1, whereas a direct interaction was observed with AKT2. These findings provide insight into the immune regulatory roles of AKT in teleosts.