Higher-affinity oligosaccharide ligands for E-selectin.
A series of synthetic oligosaccharides based on sialyl Lewis x (sLex; Neu5Ac alpha 2-3Gal beta 1-4[Fuc alpha 1-3]GlcNAc) and sialyl Lewis a (sLea; Neu5Ac alpha 2-3Gal beta 1-3[Fuc alpha 1-4]GlcNAc) was used to study the binding interactions of selectins. E-selectin-immunoglobulin fusion protein (E-selectin-Ig) bound to immobilized bovine serum albumin (BSA)-neoglycoproteins containing sLex or sLea in a Ca(2+)-dependent manner. Solution-phase sLex tetrasaccharide blocked this interaction by 50% at a concentration of 750 +/- 20 microM (IC50). sLea was more effective (IC50 = 220 +/- 20 microM), while nonsialylated, nonfucosylated derivatives showed little or no activity at concentrations up to 1 mM. Attachment of an 8-methoxycarbonyloctyl aglycone in a beta linkage to the anomeric carbon of the GlcNAc of sLex or sLea increased their blocking activity nearly twofold. Finally, replacement of the 2-N-acetyl substituent of the GlcNAc by an azido or amino group resulted in substantial increases in activity, with the most potent inhibitor being amino substituted sLea, which was 36-fold more active (IC50 = 21 +/- 3 microM) than the reducing tetrasaccharide sLex. In contrast to results obtained with E-selectin-Ig, P-selectin-Ig binding to immobilized BSA-sLea was blocked modestly by most oligosaccharides at 1 mM, with no substantial differences among them. IC50 values of soluble oligosaccharides determined in competitive binding studies accurately predicted blocking of leukocyte adhesion to recombinant E-selectin-Ig and to cytokine-activated endothelium.
Nelson
R M
RM
Howard Hughes Medical Institute, University of California, San Diego, La Jolla 92093-0669.
Dolich
S
S
Aruffo
A
A
Cecconi
O
O
Bevilacqua
M P
MP
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D019040:E-Selectin; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics / Q000378:metabolism; D007983:Lewis Blood Group Antigens; D008024:Ligands; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009844:Oligosaccharides / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship
D015815:Cell Adhesion Molecules; D019040:E-Selectin; D007143:Immunoglobulin Heavy Chains; D007983:Lewis Blood Group Antigens; D008024:Ligands; D009844:Oligosaccharides; D011993:Recombinant Fusion Proteins