Identification and characterization of a novel IκB-ε-like gene from Lamprey (Lampetra japonica) with a role in immune response

Nuclear factor of kappa B (NF-kappa B) is a stimuli-activated transcription factor, regulates the expression of a diverse array of genes. Inhibitor of kappa B-epsilon (I kappa B-epsilon) is an inhibitor of NF-kappa B, which retains NF-kappa B in an inactive state in the cytoplasm. Lampreys (Lampetra japonica) belong to the lowest class of vertebrates with little information about its I kappa Bs. We have identified a cDNA sequence I kappa B-epsilon-like in the lamprey and the deduced amino acid sequence of I kappa B-epsilon-like. It contains a conserved DSGxxS motif and six consecutive ankyrin repeats, which are necessary for signal-induced degradation of the molecule. Phylogenetic analysis indicated it had high sequence homology with I kappa B-epsilon s from other vertebrates. FACS analysis showed that I kappa B-epsilon-like located in cytoplasm of leukocytes. The degradation of I kappa B-epsilon-like could be observed in leukocytes of L japonica stimulated with lipopolysaccharide. These results indicate that I kappa B-epsilon proteins are conserved across vertebrates and the NF-kappa B-like signaling pathway may exist in the oldest agnatha. (C) 2013 Published by Elsevier Ltd.