Characterization of a novel Le(x)-active ganglioside from chick intestinal tissues recognized by murine monoclonal antibody 188C1

A phylogenetic view and functional annotation of the animal β1,3-glycosyltransferases of the GT31 CAZy family

The formation of β1,3-linkages on animal glycoconjugates is catalyzed by a subset of β1,3-glycosyltransferases grouped in the Carbohydrate-Active enZYmes family glycosyltransferase-31 (GT31). This family represents an extremely diverse set of β1,3-N-acetylglucosaminyltransferases [B3GNTs and Fringe β1,3-N-acetylglucosaminyltransferases], β1,3-N-acetylgalactosaminyltransferases (B3GALNTs), β1,3-galactosyltransferases [B3GALTs and core 1 β1,3-galactosyltransferases (C1GALTs)], β1,3-glucosyltransferase (B3GLCT) and β1,3-glucuronyl acid transferases (B3GLCATs or CHs). The mammalian enzymes were particularly well studied and shown to use a large variety of sugar donors and acceptor substrates leading to the formation of β1,3-linkages in various glycosylation pathways. In contrast, there are only a few studies related to other metazoan and lower vertebrates GT31 enzymes and the evolutionary relationships of these divergent sequences remain obscure. In this study, we used bioinformatics approaches to identify more than 920 of putative GT31 sequences in Metazoa, Fungi and Choanoflagellata revealing their deep ancestry. Sequence-based analysis shed light on conserved motifs and structural features that are signatures of all the GT31. We leverage pieces of evidence from gene structure, phylogenetic and sequence-based analyses to identify two major subgroups of GT31 named Fringe-related and B3GALT-related and demonstrate the existence of 10 orthologue groups in the Urmetazoa, the hypothetical last common ancestor of all animals. Finally, synteny and paralogy analysis unveiled the existence of 30 subfamilies in vertebrates, among which 5 are new and were named C1GALT2, C1GALT3, B3GALT8, B3GNT10 and B3GNT11. Altogether, these various approaches enabled us to propose the first comprehensive analysis of the metazoan GT31 disentangling their evolutionary relationships.

The glycosphingolipid receptor for Vibrio trachuri in the red sea bream intestine is a GM4 ganglioside which contains 2-hydroxy fatty acids

Three major glycosphingolipids (tentatively designated IGL-1, 2, and 3) were isolated from the intestine of red sea bream (Pagrus major) and were subjected to a TLC-overlay assay with (35)S-labeled Vibrio trachuri which causes vibriosis of fish. The bacteria adhered to IGL-2, which was determined to be a GM4 ganglioside (NeuAcalpha2-3Galbeta1-ceramide). The fatty acid portion of IGL-2 was composed of 2-hydroxy C22:0, C24:0, and C24:1, in addition to the non-hydroxy C16:0 and C18:0, while the sphingoid base was composed exclusively of sphingenine (d18:1). Among glycosphingolipids tested, V. trachuri adhered to GM4 the most strongly followed by adherence to GM3 and GalCer, but the bacteria did not adhere to GM1a, GM2, LacCer, or GlcCer. V. trachuri was found to aggregate with the erythrocytes coated with GM4, but not with those coated with GM1a or GM2, thus indicating that specific adhesion occurs on intact cells. Interestingly, the dynamics for adhesion of V. trachuri to glycosphingolipids was defined by the structure of not only the sugar moiety but also the ceramide moiety, since the bacteria adhered to GM4 which contained 2-hydroxy fatty acids much more strongly than to that which contained non-hydroxy fatty acids.

Recognition of cell surface GD3 by monoclonal antibody anti-6C2 in rheumatoid arthritis synovial fluid: expression on human T cells with transendothelial migratory activity

OBJECTIVE

We have previously reported that the anti-6C2 monoclonal antibody (mAb) defines a subset of human CD4+ memory T cells. The present study sought to determine the nature of the 6C2 molecule and the function associated with 6C2+ T cells, and to examine whether this T cell subset is involved in the pathophysiology of rheumatoid arthritis (RA).

METHODS

Cytofluorographic analysis was performed for identification of T cell surface molecules displaying a distribution similar to that of the 6C2 molecule. T cells in the synovial fluid of RA patients were examined for expression of the 6C2 molecule. Transendothelial migratory activity was assessed by assay using monolayers of human endothelial cells. Specific reactivity of the anti-6C2 mAb was determined by immunoblotting on gangliosides separated by thin-layer chromatography, and flow cytometric analysis of the cells transfected with complementary DNA (cDNA) was performed for determination of the glycosyltransferases involved in biosynthesis of the gangliosides.

RESULTS

On human peripheral T cells, the 6C2 molecule was distributed, by and large, in a pattern similar to that of CDw60, or O-acetyl-GD3. The majority (>70%) of synovial fluid T cells from patients with RA were found to be 6C2 positive, and those 6C2+ T cells exhibited a transendothelial migratory capacity that was inhibited by pretreatment of T cells with anti-6C2 mAb. Moreover, treatment of T cells with neuraminidase resulted in a loss of 6C2 expression as well as a reduction in the transendothelial migratory activity. Anti-6C2 mAb reacted specifically with GD3, but not with O-acetyl-GD3. The reactivity of anti-6C2 mAb was induced on the cell surface only by transfection with cDNA for GD3 synthase.

CONCLUSION

The 6C2 molecule is a disialoganglioside, GD3, and is present on a subset of T cells with transendothelial migratory capacity. The 6C2/GD3 molecules, as well as 6C2/GD3+ T cells, appear to play a role in T cell migration and in the inflammation of RA.

Immunohistochemical demonstration of glycoconjugates bearing the type 2 chain-backbone structure in human fetal, normal and neoplastic gastrointestinal tract

Immunohistochemical distributions of carbohydrate antigens based on the type 2 chain in normal as well as fetal and neoplastic tissues of human gastrointestinal tract were investigated with a monoclonal antibody (MAb) H11 (specific for type 2 chain) alone and in combination with the two MAbs MSG15 (for alpha 2----6 sialylated type 2 chain) and IB9 (for the alpha 2----6 sialylated type 2 chain and glycoproteins having NeuAc alpha 2----6Gal-NAc), and 188C1 (for short- and long-chain Lex antigens) and FH2 (for the long-chain Lex antigen). In the pyloric mucosa of secretors, the type 2 chain is oncodevelopmentally expressed, but in non-secretors it is detected in surface mucous cells of normal gastric mucosa. The alpha 2----6 sialylation, which is confined to endocrine cells of normal pyloric mucosa, occurs in fetal and carcinoma tissues. Irrespective of the secretor status, the short- and the long-chain Lex antigens can be detected in mature and immature glandular mucous cells of normal gastric mucosa, respectively; both antigens are also expressed in fetal and carcinoma tissues. In the colon, the type 2 chain and its alpha 2----6 sialylated counterpart are expressed in an oncodevelopmental manner. The short- and the long-chain Lex antigens are significantly enhanced in colonic carcinoma. The glycoproteins with NeuAc alpha 2----6GalNAc residues appear in gastric and colonic carcinoma as well as intestinalized gastric mucosa and transitional mucosa. Thus, some of these antigens were distinctively expressed in certain epithelial cells lining the normal gastrointestinal tract depending on maturation and patients' secretor status, and some were oncodevelopmental or carcinoma-associated antigens of the human gastrointestinal tract.