title: Cross-linking of CD59 and of other glycosyl phosphatidylinositol-anchored molecules on neutrophils triggers cell activation via tyrosine kinase.
abstract: Many membrane proteins are attached via a glycosyl phosphatidylinositol (GPI) anchor. Proteins anchored in this way make no direct contact with the interior of the cell, therefore a role in signaling or activation would seem unlikely. Nevertheless, cross-linking of GPI-anchored proteins on human and murine T lymphocytes has been shown to cause calcium transients and cell activation. Our studies address the non-lethal events caused by the membrane attack complex of complement, which include release of Ca2+ from intracellular stores, and have suggested that the GPI-anchored complement inhibitor CD59 may be involved in signaling these events. We here report that cross-linking of CD59 on human neutrophils using specific monoclonal antibody and second antibody caused a rapid increase in intracellular free Ca2+ concentration (Ca2+ transient) due to release of Ca2+ from stores and also caused neutrophil oxidase activation. All antibodies against CD59 tested were effective and cross-linking of any other GPI-anchored protein expressed on neutrophils also initiated an increase in intracellular free Ca2+ concentration, whereas cross-linking of transmembrane proteins caused little or no response. A tyrosine kinase-dependent activation pathway was indicated by the demonstration of tyrosine phosphorylation on cross-linking and by blocking of the Ca2+ transient with the tyrosine kinase inhibitor herbimycin.
authors.affiliation: Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, GB.
authors.forename: B P
authors.initials: BP
authors.lastname: Morgan
authors.forename: C W
authors.initials: CW
authors.lastname: van den Berg
authors.forename: E V
authors.initials: EV
authors.lastname: Davies
authors.forename: M B
authors.initials: MB
authors.lastname: Hallett
authors.forename: V
authors.initials: V
authors.lastname: Horejsi
mesh_terms: D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D016227:Benzoquinones; D018957:CD59 Antigens; D002118:Calcium / Q000378:metabolism; D003432:Cross-Linking Reagents; D004789:Enzyme Activation; D017261:Glycosylphosphatidylinositols / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D047029:Lactams, Macrocyclic; D008562:Membrane Glycoproteins / Q000378:metabolism*; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D051381:Rats; D016897:Respiratory Burst; D017828:Rifabutin / Q000031:analogs & derivatives; D012756:Sheep; D015398:Signal Transduction / Q000276:immunology / Q000502:physiology
chemical_list: D015703:Antigens, CD; D016227:Benzoquinones; D018957:CD59 Antigens; D003432:Cross-Linking Reagents; D017261:Glycosylphosphatidylinositols; D047029:Lactams, Macrocyclic; D008562:Membrane Glycoproteins; D011809:Quinones; D017828:Rifabutin; C020754:herbimycin; D011505:Protein-Tyrosine Kinases; D002118:Calcium