α2,3‐Sialyl and α1,3‐fucosyltransferase‐dependent synthesis of sialyl Lewis x, an essential oligosaccharide present on L‐selectin counterreceptors, in cultured endothelial cells

Abstract

Sialyl Lewis x (sLex) oligosaccharides have been shown to be present in counterreceptors for L-selectin. We and others have previously shown that high endothelial cells in lymph nodes and at sites of inflammation express sLex. Here we show that also cultured human umbilical vein endothelial cells (HUVEC) express sLex on their cell surface. This oligosaccharide is formed by sequential action of alpha 2,3-sialyl- (alpha 2,3-ST) and alpha 1,3-fucosyltransferases (alpha 1,3-FT) on N-acetyllactosamine. At least two of the several alpha 2,3-ST and four of the several alpha 1,3-FT are present in HUVEC. In functional assays both alpha 2,3-ST and alpha 1,3-FT activities were observed in HUVEC lysates with exogenous lactosamine and sialyllactosamine acceptors, leading to the generation of the sialyllactosamine and sLex sequences, respectively. TNF stimulation increased the level of mRNA expression of FT VI, and the alpha 1,3-FT activity in HUVEC. Taken together these data show that endothelial cells express sLex and that they possess mRNA as well as enzyme activities of several alpha 2,3-ST and alpha 1,3-FT necessary in the final steps of sLex synthesis. Furthermore, inflammatory cytokines such as TNF can enhance transferase activities relevant in generating putative L-selectin counterreceptors.

Lewis x Antigen Mediates Adhesion of Human Breast Carcinoma Cells to Activated Endothelium. Possible Involvement of the Endothelial Scavenger Receptor C-type Lectin

“…We then examined the effect of anti-Le x mAbs on lysis of tumor or normal cells. HUVEC did not suffer CDC in the presence of anti-Le x mAbs, as expected due to their undetectable Le x surface expression [35]. In this paper, we demonstrated that both anti-Le x mAbs efficiently lysed Le x+ MCF-7 cells in the presence of C′, both in suspension and adhered to HUVEC.…”

“…Figure 1a); PMN were added to HUVEC to serve as positive controls of FC-2.15 reactivity (Figure 1b), as previously demonstrated [27]. Flow cytometry studies with mAbs FC-2.15 and MCS-1, or CSLEX1, respectively, confirmed the lack of Le x and sLe x expression in HUVEC (Figure 2) [35]. On the contrary, MCF-7 and PMN showed high levels of Le x and sLe x surface expression (Figure 2).…”

Improved enzymatic synthesis of a highly potent oligosaccharide antagonist of L‐selectin

“…Inflammatory stimuli induce the expression of the sLex type saccharides on the surface of the endothelium [3] to attract L-selectin-expressing lymphocytes to the graft. We have shown previously that a triply branched poly-./V-acetyllactosamine, sLexßl-3'(sLexßl-6')LacNAcßl-3'(sLexßl-6')LacNAcßl-3'(sLexßl-6')LacNAc (7) (where *Corresponding author.…”

Terminal Galactosylation and Sialylation Switching on Membrane Glycoproteins upon TNF-Alpha-Induced Insulin Resistance in Adipocytes

“…For example, TNF-alpha modulates the expression of alpha2,3-sialyltransferases in a range of cells and tissues (17)(18)(19)(20) resulting in an increase in the sialyl-Lewis X epitope displayed on glycoproteins. There is growing evidence for a direct link between protein glycosylation and the pathogenesis of T2D.…”