The gene structure and expression of the non-specific cytotoxic cell receptor protein (NCCRP-1) in Atlantic cod (Gadus morhua L.).

The non-specific cell receptor protein (NCCRP-1) serves an important function in target cell recognition and activation of non-specific cytotoxic cells in teleosts. Atlantic cod NCCRP-1 was identified in a suppression-subtractive cDNA library and NCCRP-1 from Atlantic salmon, rainbow trout, Japanese medaka and fathead minnow was found deposited in the GenBank as EST sequences. The predicted amino acid sequences of these receptors contain the characteristic functional domains representing NCCRP-1, and phylogenetic analyses support the identification of five NCCRP-1 orthologues. Cod NCCRP-1 is shorter and has a different intron/exon organization from the common carp and channel catfish counterparts, but shows high extent of conservation in NCCRP-1 signature motives. Quantitative real-time PCR analyses showed that the gene expression of cod NCCRP-1 was higher in the lymphoid organs, head kidney (90-fold) and spleen (30-fold), compared to the organ with lowest expression. NCCRP-1 gene expression was not induced by in vitro treatment of head kidney cells with polyinosinic polycytidylic acid (poly I:C) or lipopolysaccharide (LPS), or by in vivo injections with poly I:C or formalin killed Vibrio anguillarum. These results show that the cod NCCRP-1 gene is differentially expressed in organs, and that gene expression is not induced by the tested treatments.