title: Identification of L-selectin binding heparan sulfates attached to collagen type XVIII.
abstract: L-selectin is a C-type lectin expressed on leukocytes that is involved in both lymphocyte homing to the lymph node and leukocyte extravasation during inflammation. Known L-selectin ligands include sulfated Lewis-type carbohydrates, glycolipids, and proteoglycans. Previously, we have shown that in situ detection of different types of L-selectin ligands is highly dependent on the tissue fixation protocol used. Here we use this knowledge to specifically examine the expression of L-selectin binding proteoglycans in normal mouse tissues. We show that L-selectin binding chondroitin/dermatan sulfate proteoglycans are present in cartilage, whereas L-selectin binding heparan sulfate proteoglycans are present in spleen and kidney. Furthermore, we show that L-selectin only binds a subset of renal heparan sulfates, attached to a collagen type XVIII protein backbone and predominantly present in medullary tubular and vascular basement membranes. As L-selectin does not bind other renal heparan sulfate proteoglycans such as perlecan, agrin, and syndecan-4, and not all collagen type XVIII expressed in the kidney binds L-selectin, this indicates that there is a specific L-selectin binding domain on heparan sulfate glycosaminoglycan chains. Using an in vitro L-selectin binding assay, we studied the contribution of N-sulfation, O-sulfation, C5-epimerization, unsubstituted glucosamine residues, and chain length in L-selectin binding to heparan sulfate/heparin glycosaminoglycan chains. Based on our results and the accepted model of heparan sulfate domain organization, we propose a model for the interaction of L-selectin with heparan sulfate glycosaminoglycan chains. Interestingly, this opens the possibility of active regulation of L-selectin binding to heparan sulfate proteoglycans, e.g. under inflammatory conditions.
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, 1007 MB, Amsterdam, the Netherlands. p.celie@vumc.nl
authors.forename: Johanna W A M
authors.initials: JW
authors.lastname: Celie
authors.forename: Eelco D
authors.initials: ED
authors.lastname: Keuning
authors.forename: Robert H J
authors.initials: RH
authors.lastname: Beelen
authors.forename: Angelika M
authors.initials: AM
authors.lastname: Dräger
authors.forename: Sonja
authors.initials: S
authors.lastname: Zweegman
authors.forename: Floortje L
authors.initials: FL
authors.lastname: Kessler
authors.forename: Raija
authors.initials: R
authors.lastname: Soininen
authors.forename: Jacob
authors.initials: J
authors.lastname: van den Born
mesh_terms: D000818:Animals; D043170:Collagen Type XVIII / Q000378:metabolism*; D006497:Heparan Sulfate / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000737:chemistry; D019041:L-Selectin / Q000378:metabolism*; D008024:Ligands; D051379:Mice; D008810:Mice, Inbred C57BL; D011485:Protein Binding; D011509:Proteoglycans / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D019087:Selectins; D013379:Substrate Specificity; D014018:Tissue Distribution
chemical_list: D043170:Collagen Type XVIII; D006497:Heparan Sulfate; D019041:L-Selectin; D008024:Ligands; D011509:Proteoglycans; D019087:Selectins