α(1,2)‐Fucosylation prevents sialyl Lewis x expression and E‐selectin‐mediated adhesion of fucosyltransferase VII‐transfected cells

Abstract

E-selectin is a cytokine-inducible, calcium-dependent endothelial cell adhesion molecule that plays a critical role in the leucocyte±endothelium interaction during inflammation and is thought to contribute to the metastatic dissemination of tumour cells. Like the other selectins, E-selectin binds to ligands carrying the tetrasaccharide sialyl-Lewis x (NeuAca2,3Galb1,4[Fuca1,3]GlcNAc) 1 or its isomer sialyl-Lewis a (NeuAca2, 3Galb1,3[Fuca1,4]GlcNAc). We examined the effect of expressing the H-type a(1,2)-fucosyltransferase or the a(2,6)-sialyltransferase on the synthesis of sialyl-Lewis x by a(1,3)fucosyltransferase. We found that H-type a(1,2)-fucosyltransferase but not a(2,6)-sialyltransferase, strongly inhibited sialyl-Lewis x expression and E-selectin adhesion. We assume that H-type a(1,2)-fucosyltransferase competes with the endogenous a(2,3)-sialyltransferase for the N-acetyllactosamine structures assigned to further serve as acceptors for a(1,3)fucosyltransferase.Keywords: a(1,2)-fucosyltransferase; a(2,6)-sialyltransferase; adhesion; E-selectin; sialyl-Lewis x.The carbohydrate moieties of glycoconjugates are important in molecular recognition, cell signalling and cell±cell interactions [1]. Fucosylated carbohydrates, such as sialylLewis x (sLe x ; NeuAca2,3Galb1,4[Fuca1,3]GlcNAc) or its isomer sialyl-Lewis a (sLe a ; NeuAca2,3Galb1,3[Fuca1,4] GlcNAc) for example, are known to be ligands for selectins [2] and are regarded as tumour-associated antigens, the expression of which seems to be related to the metastasizing capacity of cancer cells [3,4]. In fact, the number of sLe x and sLe a structures are increased in carcinoma cells [5±7] and a correlation has been shown between increased expression of sialyl-Lewis antigens and metastatic potential [8±11].The synthesis of sialyl-Lewis antigens is catalysed by an ordered series of glycosylation reactions; the final reaction being controlled by one or more a(1,3/1,4)-fucosyltransferases. To date, five human fucosyltransferases (FucT-III to FucT-VII), involved in the synthesis of Lewis-related antigens have been cloned [12]. Multiple molecular species of these fucosyltransferases have been found in various epithelial cancer and leukaemia cell lines [13,14]. However, although expression of a(1,3)±fucosyltransferase genes correlates with E-selectinmediated adhesion and metastatic potential [15], no single fucosyltransferase could be correlated with the expresion of sLe x and the ability of tumour cells to bind E-selectin [16].Several strategies have been developed to inhibit selectin± carbohydrate interactions including, anti-selectin sera [17], oligosaccharides related to sLe x /sLe a [18,19], molecular mimics of sLe x [20] or oligonucleotides [21] and, more recently, recombinant glycoproteins [22]. Inhibiting the glycosyltransferases that participate in forming the carbohydrate ligands would provide another way to block tumour cell adhesion to the endothelium. Given that high expression of H-type a(1,2)-fucosyltransferase (HT) has been found to reduce terminal a(...

Relative sialylation and fucosylation of synovial and plasma fibronectins in relation to the progression and activity of rheumatoid arthritis

“…Namely, the heavily sialylated Lewis X structure are unable to react with LTA [45]. Also, the biosynthesis of a1-2-linked fucose, a characteristic monosacharide for bifucosylated Lewis b and Lewis y structures, prevents sialyl-Lewis x formation [42].…”

“…LTA (Tetragonolobus purpureus agglutinin) and UEA (Ulex europaeus agglutinin) are known to have main binding preference to fucose linked by a1-3 [45] and a1-2 [2] glycosidic bonds in N-and O-glycans respectively. However, the terminal sialic acid limits fucose binding by UEA [2] and sialylation as well as a1-2 fucosylation prevent fucose-linked a1-3 binding by LTA [42,45].…”

Exploring the Acceptor Substrate Recognition of the Human β-Galactoside α2,6-Sialyltransferase

“…FITC-SNA labeling was assayed essentially as reported (32). Briefly, cells were fixed for 5 min with 0.5% paraformaldehyde in calcium-and magnesium-containing PBS and incubated with 50 g/ml lectin for 60 min on ice.…”

Terminal monosaccharide screening of synovial immunoglobulins G and A for the early detection of rheumatoid arthritis

“…None of the fucose-speciWc lectins has an absolute speciWcity; however, Aleuria aurantia lectin [20] mainly reacts with the innermost 1,6-linked fucose to a core N-acetylglucosamine of N-glycans and with lower aYnity with 1,2-and 1,3-linked fucoses of the outer arms, whereas Lotus tetragonolobus agglutinin [21] and Ulex europaeus agglutinin [22] are known to recognize 1,3-linked and 1,2-linked fucoses to the galactose or N-acetylglucosamine of the antennas, respectively. However, the terminal 2,3-sialic acid limits the binding of LTA to 1,3-linked fucose of Lewis x structure [21] and the appearance of a 1,2-fucosylated structure reduces the attachment of 2,3-sialic acid to glycans [23].…”