Characterization of the CD28 signaling pathway related genes (CD28, Grb2 and SLP-76) of golden pompano (Trachinotus ovatus).

CD28 signaling pathway plays critical roles in the T cell activation. The golden pompano (Trachinotus ovatus, Tro) is a commercially important marine fish that widely cultured in southern China. Frequently pathogenic disease outbreaks greatly hinder the industry of golden pompano. Understanding the T cell activation signaling pathway of golden pompano contributes to prevent pathogenic diseases using immunological strategies. In the present study, three molecules of CD28 signaling pathway (TroCD28, growth factor receptor-bound protein 2 (TroGrb2) and SH2 domain-containing leukocyte phosphoprotein of 76 kDa (TroSLP-76)) were identified from golden pompano. The cDNA of the three genes respectively encoded 248, 217 and 375 amino acids. TroCD28, TroGrb2 and TroSLP-76 contained several conserved functional domains, similar to their mammalian counterparts. qPCR analysis revealed that these three genes were ubiquitously expressed in all selected tissues and peripheral blood lymphocytes (PBLs), with high expressions in immune-related tissues (spleen, head kidney, gill). Further, expressions of these three genes in head kidney were significantly induced at different time points post lipopolysaccharide (LPS) or polyriboinosinic polyribocytidylic acid (polyI:C) stimulation and Vibrio alginolyticus infection. The coimmunoprecipitation (Co-IP) assay verified the TroCD28-TroGrb2 interaction. These results provide basis for understanding the process of T cell activation in golden pompano.