title: Differential O-glycosylation in cortical and medullary thymocytes.
abstract: Differentiation of T lymphocytes is characterized by variable expression of CD8/CD4 co-receptor molecules and changes in the glycosylation pattern. In this work, O-glycosylation was analyzed in microsomes from murine thymocytes purified with the PNA and Amaranthus leucocarpus (ALL) lectins, specific for the T antigen (Gal beta1,3GalNAc1,0 Ser/Thr) in cortical and medullary thymocytes, respectively. Three peptides were used as acceptors for UDP-N-acetylgalactosamine: polypeptide N-acetylgalactosaminyl-transferase (GalNAc transferase); the peptide motif TTSAPTTS was the best glycosylated one. Cortical ALL-PNA+ thymocytes showed two-fold higher GalNAc transferase activity than ALL+PNA- thymocytes; however, capillary electrophoresis showed a higher proportion of di- versus mono-glycosylated peptides for ALL+PNA- than for ALL-PNA+. We compared the GalNAc transferase activity of thymocytes from dexamethasone-treated mice versus control mice. GalNAc transferase activity was six-fold higher in thymocytes from control mice than from dexamethasone-treated mice; the rate of di-glycosylated peptides for dexamethosone-resistant ALL+ was two-fold higher than for ALL- thymocytes. Our results confirm an upregulated biosynthesis of O-glycosidically linked glycans on T cell surface glycoproteins, and suggest that the modification of GalNAc transferase activity plays a relevant role during the maturation process of thymic cells.
authors.affiliation: Laboratorio de Inmunología, Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, P.O. Box 70159, 04510, Mexico.
authors.forename: Georgina
authors.initials: G
authors.lastname: Alvarez
authors.forename: Ricardo
authors.initials: R
authors.lastname: Lascurain
authors.forename: Pedro
authors.initials: P
authors.lastname: Hernández-Cruz
authors.forename: Daniel
authors.initials: D
authors.lastname: Tetaert
authors.forename: Pierre
authors.initials: P
authors.lastname: Degand
authors.forename: Patricia
authors.initials: P
authors.lastname: Gorocica
authors.forename: Blanca
authors.initials: B
authors.lastname: Espinosa
authors.forename: Edgar
authors.initials: E
authors.lastname: Zenteno
authors.forename: Raúl
authors.initials: R
authors.lastname: Chávez
mesh_terms: D000818:Animals; D003907:Dexamethasone / Q000494:pharmacology; D019075:Electrophoresis, Capillary; D006031:Glycosylation; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D018613:Microscopy, Confocal; D008861:Microsomes / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: D003907:Dexamethasone