Cloning and Expression of the c-Jun Gene in Immune Response to Pathogen Challenge in Half-Smooth Tongue Sole (Cynoglossus semilaevis)

Abstract:

The transcription factor c-Jun (jun proto-oncogene) of AP-1 family and its role in immune response is unknown in half-smooth tongue sole (Cynoglossus semilaevis) so far. Based on c-Jun genetic partial cDNA sequence of half-smooth tongue sole, the complete cDNA sequence is obtained by RACE and PCR application. The cDNA of c-Jun is 2093 bp in length, including a 377 bp 5¢-terminal untranslated region (UTR), a 735 bp 3¢-terminal UTR and a 981 bp open reading frame (ORF), encoding a polypeptide of 326 amino acids. The deduced amino acid sequence of c-Jun possesses a Jun domain which is a typical structure domain in AP-1 family and a high conservative leucine zipper structure domain (BRLZ). The protein sequence alignment and phylogenetic tree analysis suggested that the half-smooth tongue sole c-Jun gene is closely related to that of the rainbow trout’s (Oncorhynchus mykiss). Tissue expression analysis by quantitative real-time reverse transcription PCR showed that the c-Jun mRNA was constitutively expressed in all examined tissues with the predominant expression in the ovay. After infection with Vibrio anguillarum, the half-smooth tongue sole c-Jun transcript levels exhibited distinct time-dependent response patterns in the liver, spleen, head kidney, intestine, gill and blood. Among the tested tissues, changes in gill is the most obvious, and it reached the peak level 13.20-fold at 12 h post-infection. After challenge with different pathogenic (LPS, PGN, PolyI:C, WGP) in lymphocyte, the c-Jun gene in the WGP group showed up-regulation, while in the LPS group and PolyI:C group it showed down-regulation, while, there was no significant change in the PGN group. The results suggested that the c-Jun gene plays a vital role in the immune response in half-smooth tongue sole and might play an important role in half-smooth tongue sole host defense against the bacteria infection.