title: Early events in the activation of Fc gamma RIIA in human neutrophils: stimulated insolubilization, translocation to detergent-resistant domains, and degradation of Fc gamma RIIA.
abstract: The signal transduction mechanisms associated with the ligation of FcgammaRIIA in human neutrophils are as yet only incompletely characterized. In the present study, we have investigated the distribution and fate of FcgammaRIIA following its cross-linking. The results obtained indicate that cross-linking of FcgammaRIIA led, within a few seconds, to its translocation into a nonionic detergent-insoluble fraction. This was followed, within a couple of minutes, by a substantial loss of immunoreactive FcgammaRIIA in the cells. The stimulated degradation of FcgammaRIIA was blocked by the Src kinase inhibitor PP1 but not by wortmannin, ST-638, piceatannol, or cytochalasin B. Cross-linked FcgammaRIIA could be solubilized by saponin (in the presence of Nonidet P-40) and by beta-octylglucoside. Sucrose gradient analysis of the distribution of FcgammaRIIA revealed that its cross-linking led to its translocation into the pellets and not the light buoyant density fractions classically associated with lipid rafts. Disruption of cholesterol-containing membrane microdomains with filipin prevented the degradation of FcgammaRIIA but did not inhibit the stimulation of the pattern of tyrosine phosphorylation or the mobilization of calcium that followed FcgammaRIIA cross-linking. These data suggest that both cholesterol-rich domains and Src kinases are required for the degradation of the activated FcgammaRIIA and provide new insights into the early events following FcgammaRIIA cross-linking.
authors.affiliation: Centre de Recherche en Rhumatologie et Immunologie, Canadian Institutes for Health Research Group on the Molecular Mechanisms of Inflammation, Centre de Recherche du Centre Hospitalier de l'Université Laval, Québec, Canada.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Barabé
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Rollet-Labelle
authors.forename: Caroline
authors.initials: C
authors.lastname: Gilbert
authors.forename: Maria J G
authors.initials: MJ
authors.lastname: Fernandes
authors.forename: Samia N
authors.initials: SN
authors.lastname: Naccache
authors.forename: Paul H
authors.initials: PH
authors.lastname: Naccache
mesh_terms: D000328:Adult; D015703:Antigens, CD / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D003432:Cross-Linking Reagents / Q000378:metabolism; D003902:Detergents / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005372:Filipin / Q000494:pharmacology; D005960:Glucosides / Q000494:pharmacology; D006801:Humans; D021962:Membrane Microdomains / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D018375:Neutrophil Activation / Q000276:immunology; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017434:Protein Structure, Tertiary / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects / Q000276:immunology; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D017452:Receptors, IgG / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism* / Q000502:physiology; D012503:Saponins / Q000494:pharmacology; D015398:Signal Transduction / Q000276:immunology; D012995:Solubility; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000037:antagonists & inhibitors
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D015703:Antigens, CD; D003432:Cross-Linking Reagents; D003902:Detergents; D004791:Enzyme Inhibitors; C080568:Fc gamma receptor IIA; D005960:Glucosides; D011720:Pyrazoles; D011743:Pyrimidines; D017452:Receptors, IgG; D012503:Saponins; C018619:octyl-beta-D-glucoside; D014443:Tyrosine; D005372:Filipin; D019061:src-Family Kinases