title: Topographic requirements and dynamics of signaling via L-selectin on neutrophils.
abstract: Cross-linking of L-selectin on leukocytes signals phosphorylation of mitogen-activated protein kinases (MAPKs) leading to activation of CD18 function and enhanced transmigration on inflamed endothelium. We examined how alterations in the topography of L-selectin correlate with the dynamics of CD18 activation and phosphorylation of MAPK. Simultaneous ligation of humanized antibodies DREG55 and DREG200 provided a strategy for regulating the extent of cross-linking. Triggering of CD11b/CD18 upregulation and adhesion required clustering of L-selectin to microvillus-sized patches of approximately 0.2 microm(2). Immunofluorescence revealed that L-selectin was colocalized with high-affinity CD18. Anti-L-selectin-coated protein A microspheres indicated that a single site of contact to a 5.5-microm bead, or multiple contacts to 0.94- or 0.3-microm beads, elicited maximum neutrophil activation. Adhesion signaled via L-selectin coincided with the kinetics of MAPK phosphorylation and was inhibited by blocking p38 or p42/44 activity. These data demonstrate the capacity of L-selectin to transduce signals effecting rapid ( approximately 1 s) neutrophil adhesion that is regulated by the size and frequency of receptor clustering.
authors.affiliation: Department of Biomedical Engineering, University of California, Davis 95616, USA.
authors.forename: Chad E
authors.initials: CE
authors.lastname: Green
authors.forename: David N
authors.initials: DN
authors.lastname: Pearson
authors.forename: Nadine B
authors.initials: NB
authors.lastname: Christensen
authors.forename: Scott I
authors.initials: SI
authors.lastname: Simon
mesh_terms: D018821:CD18 Antigens / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000276:immunology; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology*; D006801:Humans; D019041:L-Selectin / Q000187:drug effects / Q000276:immunology*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000187:drug effects / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000276:immunology*; D010766:Phosphorylation / Q000187:drug effects; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000276:immunology*; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D018821:CD18 Antigens; D015815:Cell Adhesion Molecules; D011956:Receptors, Cell Surface; D019041:L-Selectin; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases