title: Diversity, molecular characterization and expression of T cell receptor γ in a teleost fish, the sea bass (Dicentrarchus labrax, L).
abstract: Two lineages of T cells, expressing either the αβ T cell receptor (TR) or the γδ TR, exist in Gnathostomes. The latter type of T cells account for 1-10 % of T cells in blood and up to 30 % in the small intestine. They may recognize unconventional antigens (phosphorylated microbial metabolites, lipid antigens) without the need of major histocompatibility class I (MH1) or class II (MH2) presentation. In this work we have described cloning and structural characterization of TR -chain (TRG) from the teleost Dicentrarchus labrax. Further, by means of quantitative PCR analysis, we analyzed TRG expression levels both in poly I:C stimulated leukocytes in vitro, and following infection with betanodavirus in vivo. Two full length cDNAs relative to TRG, with the highest peptide and nucleotide identity with Japanese flounder, were identified. A multiple alignment analysis showed the conservation of peptides fundamental for TRG biological functions, and of the FGXG motif in the FR4 region, typical of most TR and immunoglobulin light chains. A 3D structure consisting of two domains mainly folded as beta strands with a sandwich architecture for each domain was also reported. TRG CDR3 of 8-18 AA in length and diversity in the TRG rearrangements expressed in thymus and intestine for a given V/C combination were evidenced by junction length spectratyping. TRG mRNA expression levels were high in basal conditions both in thymus and intestine, while in kidney and gut leukocytes they were up-regulated after in vitro stimulation by poly I:C. Finally, in juveniles the TRG expression levels were up-regulated in the head kidney and down-regulated in intestine after in vivo infection with betanodavirus. Overall, in this study the involvement of TRG-bearing T cells during viral stimulation was described for the first time, leading to new insights for the identification of T cell subsets in fish.
authors.affiliation: Department for Innovation in Biological, Agro-Food and Forest Systems, University of Tuscia, Largo dell'Università, Viterbo, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Buonocore
authors.forename: Rosario
authors.initials: R
authors.lastname: Castro
authors.forename: Elisa
authors.initials: E
authors.lastname: Randelli
authors.forename: Marie-Paule
authors.initials: MP
authors.lastname: Lefranc
authors.forename: Adrien
authors.initials: A
authors.lastname: Six
authors.forename: Heiner
authors.initials: H
authors.lastname: Kuhl
authors.forename: Richard
authors.initials: R
authors.lastname: Reinhardt
authors.forename: Angelo
authors.initials: A
authors.lastname: Facchiano
authors.forename: Pierre
authors.initials: P
authors.lastname: Boudinot
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scapigliati
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D019675:Genes, T-Cell Receptor gamma / Q000235:genetics*; D014644:Genetic Variation; D007962:Leukocytes / Q000378:metabolism; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013950:Thymus Gland / Q000378:metabolism; D014018:Tissue Distribution
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D010455:Peptides; D016692:Receptors, Antigen, T-Cell, gamma-delta