title: Shear-dependent capping of L-selectin and P-selectin glycoprotein ligand 1 by E-selectin signals activation of high-avidity beta2-integrin on neutrophils.
abstract: Two adhesive events critical to efficient recruitment of neutrophils at vascular sites of inflammation are up-regulation of endothelial selectins that bind sialyl Lewis(x) ligands and activation of beta(2)-integrins that support neutrophil arrest by binding ICAM-1. We have previously reported that neutrophils rolling on E-selectin are sufficient for signaling cell arrest through beta(2)-integrin binding of ICAM-1 in a process dependent upon ligation of L-selectin and P-selectin glycoprotein ligand 1 (PSGL-1). Unresolved are the spatial and temporal events that occur as E-selectin binds to human neutrophils and dynamically signals the transition from neutrophil rolling to arrest. Here we show that binding of E-selectin to sialyl Lewis(x) on L-selectin and PSGL-1 drives their colocalization into membrane caps at the trailing edge of neutrophils rolling on HUVECs and on an L-cell monolayer coexpressing E-selectin and ICAM-1. Likewise, binding of recombinant E-selectin to PMNs in suspension also elicited coclustering of L-selectin and PSGL-1 that was signaled via mitogen-activated protein kinase. Binding of recombinant E-selectin signaled activation of beta(2)-integrin to high-avidity clusters and elicited efficient neutrophil capture of beta(2)-integrin ligands in shear flow. Inhibition of p38 and p42/44 mitogen-activated protein kinase blocked the cocapping of L-selectin and PSGL-1 and the subsequent clustering of high-affinity beta(2)-integrin. Taken together, the data suggest that E-selectin is unique among selectins in its capacity for clustering sialylated ligands and transducing signals leading to neutrophil arrest in shear flow.
authors.affiliation: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, CA 95616, USA.
authors.forename: Chad E
authors.initials: CE
authors.lastname: Green
authors.forename: David N
authors.initials: DN
authors.lastname: Pearson
authors.forename: Raymond T
authors.initials: RT
authors.lastname: Camphausen
authors.forename: Donald E
authors.initials: DE
authors.lastname: Staunton
authors.forename: Scott I
authors.initials: SI
authors.lastname: Simon
mesh_terms: D001665:Binding Sites; D001773:Blood Cells; D018821:CD18 Antigens / Q000378:metabolism*; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism; D002478:Cells, Cultured; D019040:E-Selectin / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D019041:L-Selectin / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism*; D021381:Protein Transport; D011940:Receptor Aggregation; D015398:Signal Transduction; D013314:Stress, Mechanical; D014162:Transfection
chemical_list: D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; D019040:E-Selectin; D008562:Membrane Glycoproteins; C084882:P-selectin ligand protein; D019041:L-Selectin; D020928:Mitogen-Activated Protein Kinases