Oligosaccharide structures of mucins secreted by the human colonic cancer cell line CL.16E.

Identification of transient glycosylation alterations of sialylated mucin oligosaccharides during infection by the rat intestinal parasite Nippostrongylus brasiliensis

“…The α2-3 linkage of the NeuAc(NHMe) (where Me is methyl) was confirmed by "H-NMR from the chemical shift of its H3 eq and the low field shift of Gal H3 (Table 3 and Figure 8A). The values found were similar to previously published values for the un-derivatized species [24,25], except for a substantial (approx. 0.14 p.p.m.)…”

“…This was consistent with the presence of terminal GlcNAc and GalNAcol substituted on both C-3 and C-6 in the linkage analysis (Table 2). Again "H-NMR (Table 3 and Figure 8B) showed a downfield shift of the NeuAc H3 ax for the N-methyl derivative compared with the shift reported for the corresponding underivatized oligosaccharide [24].…”

GalNAc-α-O-benzyl Inhibits NeuAcα2-3 Glycosylation and Blocks the Intracellular Transport of Apical Glycoproteins and Mucus in Differentiated HT-29 Cells

“…The present results suggest that in HT-29 cells, ␣2,3-sialylation plays a crucial role in intracellular transport of brush border membrane-associated glycoproteins and in mucus secretion. They rely on the exceptional conjunction of a number of factors: (a) the availability of polarized cells, isolated from the HT-29 cell line, expressing either an enterocytic or a mucus-secreting differentiated phenotype; (b) the neoplastic nature of these cells which, as such, show a modified pattern of protein glycosylation as compared with their normal counterpart with shorter oligosaccharide side chains (for review see Lesuffleur et al, 1994); (c) the fact that the main sialyltransferase activities expressed in HT-29 cells catalyze the transfer of sialic acid to the 3-position of Gal in the Gal␤1-3GalNAc disaccharide sequence (Dall'Olio et al, 1993;Majuri et al, 1995;Delannoy et al, 1996) in contrast to most colon cancers (Sata et al, 1991) or cell lines, including the enterocytic cell line Caco-2, which mainly express the Gal␤1-4GlcNAc ␣2,6-sialyltransferase, ST6Gal I as reported by others (Dall'Olio et al, 1992, 1996, and confirmed here by the reactivity to SNA of Caco-2 glycoproteins; (d) the availability of an O-glycosylation inhibitor, GalNAc-␣-O-benzyl (Kuan et al, 1989;Huang et al, 1992;Byrd et al, 1995;DiIulio and Bhavanandan, 1995), which enters the cells and is metabolized into a compound that acts as a competitive inhibitor of Gal␤1-3GalNAc ␣-2,3-sialyltransferases (Huet et al, 1995;Delannoy et al, 1996); and (e) the fact that, in differentiated HT-29 cells, NeuAc␣2-3Gal␤1-3GalNAc-R is the main oligosaccharide species associated not only with mucins, as previously reported (Capon et al, 1992;Lesuffleur et al, 1993;Huet et al, 1995), but also, as shown here, with a number of glycoproteins of the brush border concomitantly expressed in these cells. The association of NeuAc␣2-3Gal␤1-3GalNAc-R to apical glycoproteins re- The apparent discrepancy between the relatively discrete (1.6-fold) increase in DPP-IV activity and the dramatic intracellular accumulation of the enzyme (see Fig.…”

“…Whatever their phenotype, these populations share common differentiation characteristics, namely ( a ) a postmitotic onset of the differentiation process and ( b ) a polarized organization of the cell monolayer with the presence of an apical brush border endowed with several glycoproteins such as dipeptidylpeptidase-IV (DPP-IV), the carcinoembryonic antigen (CEA) and the mucin-like glycoprotein MUC1. Mucus-secreting cell populations selected by MTX have been extensively analyzed as to the characteristics of their mucins: at the mRNA level they mainly express MUC5AC (Lesuffleur et al, 1993(Lesuffleur et al, , 1995; at the protein level they secrete mucus of gastric immunoreactivity (Lesuffleur et al, 1990) with a main oligosaccharide species similar to the clone HT29-16E (Capon et al, 1992), NeuAc ␣ 2-3Gal ␤ 1-3GalNAc-R (sialyl T antigen) (Lesuffleur et al, 1993;Huet et al, 1995).…”

Selectin ligands: 2,3,4-tri-O-acetyl-6-O-(2-naphthyl)methyl (NAP) α-d-galactopyranosyl imidate as a novel glycosyl donor for the efficient total synthesis of branched mucin core 2-structure containing the NeuAcα2,3(SO3Na-6)Galβ1,3GalNAcα sequence

“…Moreover, the sequences (SO 3 Na-6)Galb-1,3GalNAca and especially NeuAca2,3(SO 3 Na-6)Galb1,3Gal-NAca have been found to be part of O-linked glycoproteins. 3 Thus, we turned our attention to the synthesis of our target molecule 2, which contains the NeuAca2,3(SO 3 Na-6)Galb-1,3GalNAca sequence, as a potential ligand.…”