title: A role for Syk-kinase in the control of the binding cycle of the beta2 integrins (CD11/CD18) in human polymorphonuclear neutrophils.
abstract: A fine control of beta(2) integrin (CD11/CD18)-mediated firm adhesion of human neutrophils to the endothelial cell monolayer is required to allow ordered emigration. To elucidate the molecular mechanisms that control this process, intracellular protein tyrosine signaling subsequent to beta(2) integrin-mediated ligand binding was studied by immunoprecipitation and Western blotting techniques. The 72-kDa Syk-kinase, which was tyrosine-phosphorylated upon adhesion, was found to coprecipitate with CD18, the beta-subunit of the beta(2) integrins. Moreover, inhibition of Syk-kinase by piceatannol enhanced adhesion and spreading but diminished N-formyl-Met-Leu-Phe-induced chemotactic migration. The enhancement of adhesiveness was associated with integrin clustering, which results in increased integrin avidity. In contrast, piceatannol had no effect on the surface expression or on the affinity of beta(2) integrins. Altogether, this suggests that Syk-kinase controls alternation of beta(2) integrin-mediated ligand binding with integrin detachment.
authors.affiliation: Department of Physiology, Ludwig-Maximilians-Universität München, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Willeke
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schymeinsky
authors.forename: Peggy
authors.initials: P
authors.lastname: Prange
authors.forename: Stefan
authors.initials: S
authors.lastname: Zahler
authors.forename: Barbara
authors.initials: B
authors.lastname: Walzog
mesh_terms: D015153:Blotting, Western; D018845:CD11 Antigens / Q000378:metabolism*; D018821:CD18 Antigens / Q000378:metabolism*; D002448:Cell Adhesion; D002465:Cell Movement / Q000187:drug effects; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004792:Enzyme Precursors / Q000037:antagonists & inhibitors / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013267:Stilbenes / Q000494:pharmacology; D000072377:Syk Kinase; D014443:Tyrosine / Q000378:metabolism
chemical_list: D018845:CD11 Antigens; D018821:CD18 Antigens; D004791:Enzyme Inhibitors; D004792:Enzyme Precursors; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D013267:Stilbenes; D014443:Tyrosine; D009240:N-Formylmethionine Leucyl-Phenylalanine; C041525:3,3',4,5'-tetrahydroxystilbene; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase