title: Engagement of P-selectin glycoprotein ligand-1 enhances tyrosine phosphorylation and activates mitogen-activated protein kinases in human neutrophils.
abstract: During inflammation, P-selectin on activated platelets and endothelial cells initiates adhesion of leukocytes through interactions with P-selectin glycoprotein ligand-1 (PSGL-1). We investigated whether ligation of PSGL-1 also transmits signals into leukocytes. Neutrophils incubated with anti-PSGL-1 monoclonal antibodies, but not with Fab fragments of these antibodies, rapidly increased tyrosine phosphorylation of proteins with relative molecular masses of 105-120, 70-84, and 42-44 kDa. PSGL-1-dependent adhesion of neutrophils to P-selectin increased tyrosine phosphorylation of similarly sized proteins. Cytochalasin B did not prevent the tyrosine phosphorylation induced by ligation of PSGL-1, suggesting that an intact cytoskeleton is not required for signaling. Engagement of PSGL-1 activated the GTPase Ras through a mechanism that did not require tyrosine phosphorylation of PSGL-1 or association of the Shc.Grb2.Sos1 complex with PSGL-1. Engagement of PSGL-1 activated the 42-44-kDa extracellular signal-regulated kinase family of mitogen-activated protein (MAP) kinases through a pathway that required activation of the MAP kinase kinase. Ligation of PSGL-1 also stimulated secretion of interleukin-8. The tyrosine kinase inhibitor, genistein, blocked tyrosine phosphorylation and secretion of interleukin-8, whereas the MAP kinase kinase inhibitor PD98059 partially inhibited secretion of interleukin-8. Tyrosine phosphorylation stimulated through PSGL-1 on selectin-tethered leukocytes may propagate a signaling cascade that is integrated with signals generated by other mediators.
authors.affiliation: W. K. Warren Medical Research Institute and the Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA.
authors.forename: K I
authors.initials: KI
authors.lastname: Hidari
authors.forename: A S
authors.initials: AS
authors.lastname: Weyrich
authors.forename: G A
authors.initials: GA
authors.lastname: Zimmerman
authors.forename: R P
authors.initials: RP
authors.lastname: McEver
mesh_terms: D000911:Antibodies, Monoclonal / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D008024:Ligands; D008562:Membrane Glycoproteins / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D009504:Neutrophils / Q000201:enzymology* / Q000378:metabolism; D019007:P-Selectin / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D016209:Interleukin-8; D008024:Ligands; D008562:Membrane Glycoproteins; D019007:P-Selectin; C084882:P-selectin ligand protein; D014443:Tyrosine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases