title: A balance between positive and negative signals in cytotoxic lymphocytes regulates the polarization of lipid rafts during the development of cell-mediated killing.
abstract: Plasma membrane microdomains containing sphingolipids and cholesterol (lipid rafts) are enriched in signaling molecules. The cross-linking of certain types of cell surface receptors initiates the redistribution of these lipid rafts, resulting in the formation of signaling complexes. However, little is known about the regulation of the initial raft redistribution and whether negative regulatory signaling pathways target this phase of cellular activation. We used natural killer (NK) cells as a model to investigate the regulation of raft redistribution, as both positive and negative signals have been implicated in the development of their cellular function. Here we show that after NK cells form conjugates with sensitive tumor cells, rafts become polarized to the site of target recognition. This redistribution of lipid rafts requires the activation of both Src and Syk family protein tyrosine kinases. In contrast, engagement of major histocompatibility complex (MHC)-recognizing killer cell inhibitory receptors (KIRs) on NK cells by resistant, MHC-bearing tumor targets blocks raft redistribution. This inhibition is dependent on the catalytic activity of KIR-associated SHP-1, a Src homology 2 (SH2) domain containing tyrosine phosphatase. These results suggest that the influence of integrated positive and negative signals on raft redistribution critically influences the development of cell-mediated cytotoxicity.
authors.affiliation: Department of Pharmacology, Mayo Graduate and Medical Schools, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Lou
authors.forename: D
authors.initials: D
authors.lastname: Jevremovic
authors.forename: D D
authors.initials: DD
authors.lastname: Billadeau
authors.forename: P J
authors.initials: PJ
authors.lastname: Leibson
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000276:immunology*; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D004792:Enzyme Precursors / Q000276:immunology; D015235:HLA-B Antigens / Q000276:immunology; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000276:immunology*; D051379:Mice; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000276:immunology; D011505:Protein-Tyrosine Kinases / Q000276:immunology; D011971:Receptors, Immunologic / Q000276:immunology; D054340:Receptors, KIR; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction / Q000276:immunology*; D013107:Sphingolipids / Q000276:immunology*; D000072377:Syk Kinase; D014407:Tumor Cells, Cultured; D019061:src-Family Kinases / Q000276:immunology
chemical_list: D004792:Enzyme Precursors; D015235:HLA-B Antigens; D047908:Intracellular Signaling Peptides and Proteins; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D013107:Sphingolipids; D002784:Cholesterol; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; C000606897:Syk protein, mouse; D019061:src-Family Kinases; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases