Further characterization of the interaction between L-selectin and its endothelial ligands.
L-Selectin is a lectin-like receptor on lymphocytes which mediates their attachment to high endothelial venules (HEV) within lymph nodes. Previous work has identified HEV-associated endothelial ligands for L-selectin as sialylated, fucosylated and sulphated glycoproteins of approximately 50 kDa and approximately 90 kDa (Sgp50 and Sgp90). The interaction of L-selectin with these ligands is carbohydrate directed, reflecting the involvement of its amino-terminal, calcium-type lectin domain. It has been reported, and we have confirmed, that anti-Ly22 blocks the adhesive function of L-selectin without reducing its binding to a carbohydrate- based ligand PPME (phosphomannan monoester core from Hansenula hostii). The epitope for this monoclonal antibody depends on the epidermal growth factor (EGF) domain of L-selectin. We demonstrate that anti-Ly22 inhibits the interaction of L-selectin with both of the Sgps, thus establishing that the interaction of L-selectin with HEV can be accounted for by the Sgps. Furthermore, the interaction of trypsin fragments of Sgp50 with L-selectin is inhibitable both by an antibody that maps to the lectin domain and by anti-Ly22. These findings raise the possibility that anti-Ly22 is affecting the function of the lectin domain of L-selectin rather than directly antagonizing the EGF domain. Toward a further characterization of L-selectin's carbohydrate specificity, we show that Sgp50 is partially inactivated by the linkage-specific Newcastle Disease virus sialidase (alpha 2,3 linkage). We additionally demonstrate that a sialyl Lewis x-related tetrasaccharide can interact with L-selectin, as has also been demonstrated for E-selectin and P-selectin.
Imai
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Department of Anatomy, University of California, San Francisco 94143-0452.
Lasky
L A
LA
Rosen
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SD
D000818:Animals; D000911:Antibodies, Monoclonal; D001665:Binding Sites; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D011232:Chemical Precipitation; D051152:Clusterin; D004730:Endothelium, Vascular / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism; D019041:L-Selectin; D016256:Lewis X Antigen / Q000378:metabolism; D008351:Mannans / Q000378:metabolism; D051379:Mice; D018832:Molecular Chaperones; D019158:N-Acetylneuraminic Acid; D009439:Neuraminidase / Q000494:pharmacology; D009522:Newcastle disease virus / Q000201:enzymology; D009844:Oligosaccharides / Q000378:metabolism; D010446:Peptide Fragments / Q000378:metabolism; D051381:Rats; D012794:Sialic Acids / Q000378:metabolism; D014357:Trypsin
D000911:Antibodies, Monoclonal; D015815:Cell Adhesion Molecules; C495243:Clu protein, mouse; D051152:Clusterin; D006023:Glycoproteins; D016256:Lewis X Antigen; D008351:Mannans; D018832:Molecular Chaperones; D009844:Oligosaccharides; D010446:Peptide Fragments; D012794:Sialic Acids; D019041:L-Selectin; D004815:Epidermal Growth Factor; C005437:phosphomannan; D009439:Neuraminidase; D014357:Trypsin; D019158:N-Acetylneuraminic Acid