title: Molecular cloning, differential expression and 3D structural analysis of the MHC class-II beta chain from sea bass (Dicentrarchus labrax L.).
abstract: The major histocompatibility complex class I and II molecules (MHC-I and MHC-II) play a pivotal role in vertebrate immune response to antigenic peptides. In this paper we report the cloning and sequencing of the MHC class II beta chain from sea bass (Dicentrarchus labrax L.). The six obtained cDNA sequences (designated as Dila-DAB) code for 250 amino acids, with a predicted 21 amino acid signal peptide and contain a 28bp 5'-UTR and a 478bp 3'-UTR. A multiple alignment of the predicted translation of the Dila-DAB sequences was assembled together with other fish and mammalian sequences and it showed the conservation of most amino acid residues characteristic of the MHC class II beta chain structure. The highest basal Dila-DAB expression was found in gills, followed by gut and thymus, lower mRNA levels were found in spleen, peripheral blood leucocytes (PBL) and liver. Stimulation of head kidney leukocytes with LPS for 4h showed very little difference in the Dila-DAB expression, but after 24h the Dila-DAB level decreased to a large extent and the difference was statistically significant. Stimulation of head kidney leukocytes with different concentrations of rIL-1beta (ranging from 0 to 100ng/ml) resulted in a dose-dependent reduction of the Dila-DAB expression. Moreover, two 3D Dila-DAB*0101 homology models were obtained based on crystallographic mouse MHC-II structures complexed with D10 T-cell antigen receptor or human CD4; features and differences between the models were evaluated and discussed. Taken together these results are of interest as MHC-II structure and function, molecular polymorphism and differential gene expression are in correlation with disease resistance to virus and bacteria in teleost fish.
authors.affiliation: Dipartimento di Scienze Ambientali, University of Tuscia, Largo dell'Università snc, I-01100, Viterbo, Italy. fbuono@unitus.it
authors.forename: Francesco
authors.initials: F
authors.lastname: Buonocore
authors.forename: Elisa
authors.initials: E
authors.lastname: Randelli
authors.forename: Daniela
authors.initials: D
authors.lastname: Casani
authors.forename: Susan
authors.initials: S
authors.lastname: Costantini
authors.forename: Angelo
authors.initials: A
authors.lastname: Facchiano
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scapigliati
authors.forename: Renè J M
authors.initials: RJ
authors.lastname: Stet
mesh_terms: D000276:Adjuvants, Immunologic / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D001492:Bass / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D020869:Gene Expression Profiling / Q000662:veterinary; D005786:Gene Expression Regulation / Q000187:drug effects; D000949:Histocompatibility Antigens Class II / Q000737:chemistry* / Q000235:genetics*; D021621:Imaging, Three-Dimensional; D053583:Interleukin-1beta / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment
chemical_list: D000276:Adjuvants, Immunologic; D000949:Histocompatibility Antigens Class II; D053583:Interleukin-1beta; D008070:Lipopolysaccharides