title: 2B4 (CD244)-mediated activation of cytotoxicity and IFN-gamma release in human NK cells involves distinct pathways.
abstract: 2B4 (CD244), a member of the CD2 subset of the Ig superfamily receptors, is expressed on all human NK cells, a subpopulation of T cells, basophils and monocytes. 2B4 activates NK cell mediated cytotoxicity, induces secretion of IFN-gamma and matrix metalloproteinases, and NK cell invasiveness. Although there have been several molecules shown to interact with 2B4, the signaling mechanism of 2B4-mediated activation of NK cells is still unknown. In this study, we found cross-linking of 2B4 on YT cells, a human NK cell line, results in the increased DNA binding activity of activator protein-1 (AP-1), an important regulator of nuclear gene expression in leukocytes. We investigated the possible role of various signaling molecules that may be involved in the activation of lytic function of YT cells via 2B4. Treatment of YT cells with various specific inhibitors indicate that 2B4-stimulation of YT cells in spontaneous and Ab-dependent cytotoxicity is Ras/Raf dependent and involves multiple MAPK signaling pathways (ERK1/2 and p38). However, only inhibitors of transcription and p38 inhibited 2B4-mediated IFN-gamma release indicating distinct pathways are involved in cytotoxicity and cytokine release. In this study we also show that 2B4 constitutively associates with the linker for activation of T cells (LAT) and that 2B4 may mediate NK cell activation via a LAT-dependent signaling pathway. These results indicate that 2B4-mediated activation of NK cells involves complex interactions involving LAT, Ras, Raf, ERK and p38 and that cytolytic function and cytokine production may be regulated by distinct pathways.
authors.affiliation: Department of Molecular Biology and Immunology and Institute for Cancer Research, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Chuang
authors.forename: P R
authors.initials: PR
authors.lastname: Kumaresan
authors.forename: P A
authors.initials: PA
authors.lastname: Mathew
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D015703:Antigens, CD; D002352:Carrier Proteins / Q000378:metabolism; D003602:Cytotoxicity, Immunologic / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology*; D048369:MAP Kinase Kinase 1; D008562:Membrane Glycoproteins / Q000378:metabolism / Q000502:physiology*; D008565:Membrane Proteins; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D010750:Phosphoproteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D011971:Receptors, Immunologic; D015398:Signal Transduction / Q000276:immunology*; D000071176:Signaling Lymphocytic Activation Molecule Family; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014158:Transcription, Genetic / Q000276:immunology; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases; D018631:ras Proteins / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D015703:Antigens, CD; C084093:CD244 protein, human; D002352:Carrier Proteins; C490007:Cd244a protein, mouse; C110810:LAT protein, human; C491734:Lat protein, mouse; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010750:Phosphoproteins; D011971:Receptors, Immunologic; D000071176:Signaling Lymphocytic Activation Molecule Family; D018808:Transcription Factor AP-1; D007371:Interferon-gamma; D017346:Protein Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D018631:ras Proteins