title: SH2-containing inositol phosphatase (SHIP-1) transiently translocates to raft domains and modulates CD16-mediated cytotoxicity in human NK cells.
abstract: Membrane recruitment of the SH2-containing 5' inositol phosphatase 1 (SHIP-1) is responsible for the inhibitory signals that modulate phosphatidylinositol 3-kinase (PI3K)-dependent signaling pathways. Here we have investigated the molecular mechanisms underlying SHIP-1 activation and its role in CD16-mediated cytotoxicity. We initially demonstrated that a substantial fraction of SHIP-1-mediated 5' inositol phosphatase activity associates with CD16 zeta chain after receptor cross-linking. Moreover, CD16 stimulation on human primary natural killer (NK) cells induces the rapid and transient translocation of SHIP-1 in the lipid-enriched plasma membrane microdomains, termed rafts, where it associates with tyrosine-phosphorylated zeta chain and shc adaptor protein. As evaluated by confocal microscopy, CD16 engagement by reverse antibody-dependent cellular cytotoxicity (ADCC) rapidly induces SHIP-1 redistribution toward the area of NK cell contact with target cells and its codistribution with aggregated rafts where CD16 receptor also colocalizes. The functional role of SHIP-1 in the modulation of CD16-induced cytotoxicity was explored in NK cells infected with recombinant vaccinia viruses encoding wild-type or catalytic domain-deleted mutant SHIP-1. We found a significant SHIP-1-mediated decrease of CD16-induced cytotoxicity that is strictly dependent on its catalytic activity. These data demonstrate that CD16 engagement on NK cells induces membrane targeting and activation of SHIP-1, which acts as negative regulator of ADCC function.
authors.affiliation: Department of Experimental Medicine and Pathology, Istituto Pasteur-Fondazione Cenci Bolognetti, University La Sapienza, Rome, Italy.
authors.forename: Ricciarda
authors.initials: R
authors.lastname: Galandrini
authors.forename: Ilaria
authors.initials: I
authors.lastname: Tassi
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Mattia
authors.forename: Luisa
authors.initials: L
authors.lastname: Lenti
authors.forename: Mario
authors.initials: M
authors.lastname: Piccoli
authors.forename: Luigi
authors.initials: L
authors.lastname: Frati
authors.forename: Angela
authors.initials: A
authors.lastname: Santoni
mesh_terms: D000920:Antibody-Dependent Cell Cytotoxicity; D020134:Catalytic Domain; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism*; D018613:Microscopy, Confocal; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010744:Phosphoric Monoester Hydrolases / Q000502:physiology*; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D017452:Receptors, IgG / Q000276:immunology*; D011993:Recombinant Fusion Proteins / Q000502:physiology
chemical_list: D017452:Receptors, IgG; D011993:Recombinant Fusion Proteins; D010744:Phosphoric Monoester Hydrolases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases