title: Alterations in the glycosylation of secreted thyrotropin during ontogenesis. Analysis of sialylated and sulfated oligosaccharides.
abstract: We have examined the carbohydrate structure of thyrotropin (TSH) secreted in vitro by pituitaries from prenatal, perinatal, and mature rats using concanavalin A (ConA)-agarose chromatography and anion-exchange high performance liquid chromatography (HPLC). [3H]Glucosamine-labeled TSH was immuno-precipitated and treated with either Pronase to generate glycopeptides or a mixture of endo-beta-N-acetyl-glucosaminidase F and peptide:N-glycosidase F to release oligosaccharides. The percentage of secreted TSH glycopeptides not bound to ConA was greater in mature animals (47 +/- 3%) than in either prenatal (29 +/- 3%) or perinatal animals (29 +/- 6%), suggesting more multiantennary oligosaccharides in the older animals. These structural changes were characterized further by performing anion-exchange HPLC on released oligosaccharides. Secreted TSH from prenatal rats predominantly contained oligosaccharides with 1 and 2 negative charges, while TSH from mature rats contained these structures as well as 15% with 3 negative charges. In addition, the ratio of sialylated to sulfated oligosaccharides was greater in mature compared to prenatal animals for species with 1 negative charge (1.9-fold) as well as for species with 2 negative charges (4.3-fold). We also correlated the structural alterations noted by ConA analysis with anion-exchange HPLC. Oligosaccharides that bound to ConA and were eluted with alpha-methylglucoside, when analyzed by anion-exchange HPLC, consisted of species with 1 and 2 negative charges, whereas oligosaccharides that were unbound to ConA were predominantly species with three negative charges. Together, these data suggest that with maturation of the hypothalamic-pituitary-thyroid axis secreted TSH contains more negatively charged multiantennary oligosaccharides with increased sialylation and decreased sulfation.
authors.affiliation: Molecular, Cellular and Nutritional Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
authors.forename: P W
authors.initials: PW
authors.lastname: Gyves
authors.forename: N
authors.initials: N
authors.lastname: Gesundheit
authors.forename: B S
authors.initials: BS
authors.lastname: Stannard
authors.forename: G S
authors.initials: GS
authors.lastname: DeCherney
authors.forename: B D
authors.initials: BD
authors.lastname: Weintraub
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D002846:Chromatography, Affinity; D002851:Chromatography, High Pressure Liquid; D006031:Glycosylation; D011499:Protein Processing, Post-Translational; D051381:Rats; D011919:Rats, Inbred Strains / Q000196:embryology; D012795:Sialoglycoproteins / Q000378:metabolism* / Q000648:ultrastructure; D013431:Sulfates / Q000378:metabolism; D013972:Thyrotropin / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D012795:Sialoglycoproteins; D013431:Sulfates; D013972:Thyrotropin