Expression of N-linked sialyl Lex determinants and O-glycans in the carbohydrate moiety of human amniotic fluid transferrin during pregnancy

Abstract

Transferrin, a glycoprotein involved in iron transport in body fluids, was isolated from amniotic fluid of a hydramniospatient by sequential anion-exchange chromatography and gel filtration. The N-glycans of human amniotic fluid transferrin (hAFT) were enzymatically liberated by PNGase-F digestion, isolated by gel filtration and fractionated by (high-pH) anion-exchange chromatography. After alkaline borohydride treatment of native hAFT, the released O-glycans were isolated by gel filtration and fractionated by anion-exchange chroma-tography. Structure elucidation of 14 N- and 2 O-glycans was performed by 500 or 600 MHz1H-NMR spectroscopy. Besides conventional N-glycans established earlier for human serum transferrin (hST), new (alpha1-3)-fucosylated N-glycans were found, representing sialyl Le(x) elements. Furthermore, as compared to hST, a higher degree of (alpha1-6)-fucosylation and an increase in branching from di- to triantennary compounds has been detected. The presence of O-glycans is demonstrated for the first time in transferrin.

Sialyl-Lewisx on P-Selectin Glycoprotein Ligand-1 Is Regulated during Differentiation and Maturation of Dendritic Cells: A Mechanism Involving the Glycosyltransferases C2GnT1 and ST3Gal I

“…1). sLe x is a peripheral carbohydrate structure generated by the sequential action of various glycosyltransferases and can be found linked to different types of glycoconjugates, such as O-glycans (6), complex N-glycans (8,9), or glycolipids (10).…”

Human Amniotic Fluid Glycoproteins Expressing Sialyl Lewis Carbohydrate Antigens Stimulate Progesterone Production in Human Trophoblasts in vitro

“…Glycodelin A binds to E-selectin more efficiently compared to hAFT, suggesting a glycosylation in glycodelin that is more suitable to bind to selectins. Because hAFT and serum transferrin are only different in their glycosylation [22] and hAFT in contrast to serum transferrin contains (·1-3)-fucosylated N-glycans, we assume that glycoproteins with these structures are able to stimulate progesterone production in trophoblast cells.…”

“…Human amniotic fluid transferrin (hAFT) was purified as previously published [22]. Briefly, amniotic fluid was dialyzed and fractionated on a DEAE-Sepharose (Amersham Biosciences, Uppsala, Sweden).…”

Proteomic and Postproteomic Characterization of Keratan Sulfate-Glycanated Isoforms of Thyroglobulin and Transferrin Uniquely Elaborated by Papillary Thyroid Carcinomas

“…This indicates that the alteration of transferrin in PTC occurred at all levels, ie, transcriptional, translational, and posttranslational, and was to some extent corresponded by the analogous alteration affecting the thyroglobulin gene. Interestingly, changes in the glycosylation profile of transferrin have been noted during pregnancy, 43 linking thereby the putative hormone-associated prevalence of PTC in females with aberrant glycosylations traits of the protein in neoplasia. Finally, the restricted anatomical distribution of KS in the neck region and the specific appearance of these hitherto described glycoforms in PTC also opens the avenues for the possible exploitation of antibody 373E1 and radiolabeled transferrin (normally used for gallium-67-based imaging of lymphomas) for PET-based in vivo imaging of malignant thyroid lesions.…”