title: Association of the X-linked lymphoproliferative disease gene product SAP/SH2D1A with 2B4, a natural killer cell-activating molecule, is dependent on phosphoinositide 3-kinase.
abstract: Natural killer (NK) cells express an activating receptor, 2B4, that enhances cellular cytotoxicity. Upon NK cell activation by ligation of 2B4, the intracellular domain of 2B4 associates with the X-linked lymphoproliferative disease (XLP) gene product, signaling lymphocytic activation molecule-associated protein/SH2D1A (SAP/SH2D1A). Defective intracellular association of 2B4 with mutated SAP/SH2D1A is likely to underlie the defects in cytotoxicity observed in NK cells from patients with XLP. We report here a role for phosphoinositide 3-kinase (PI3K) in the recruitment and association of SAP/SH2D1A to 2B4 in human NK cells. The activation of normal NK cells by ligation of 2B4 leads to the phosphorylation of 2B4, recruitment of SAP/SH2D1A, and association of the p85 regulatory subunit of PI3K. The inhibition of PI3K enzymatic activity with either wortmannin or LY294002 prior to 2B4 ligation does not alter the association of 2B4 with the p85 subunit but prevents the recruitment of SAP/SH2D1A to 2B4. In addition, PI3K inhibitors significantly diminish the cytotoxic function of primary NK cells. This observed inhibition of cytotoxicity, present in normal NK cells, was less apparent or absent in NK cells derived from a patient with XLP. These data indicate that the cytotoxicity of activated NK cells is mediated by the association of 2B4 and SAP/SH2D1A, and that this association is dependent upon the activity of PI3K.
authors.affiliation: Department of Pathology and Laboratory Medicine, British Columbia's Children's Hospital, University of British Columbia, 4480 Oak Street, Vancouver, BC V6H 3V4, Canada.
authors.forename: Ala
authors.initials: A
authors.lastname: Aoukaty
authors.forename: Rusung
authors.initials: R
authors.lastname: Tan
mesh_terms: D000595:Amino Acid Sequence; D000730:Androstadienes / Q000494:pharmacology; D015703:Antigens, CD; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008040:Genetic Linkage; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007694:Killer Cells, Natural / Q000378:metabolism*; D008213:Lymphocyte Activation; D008232:Lymphoproliferative Disorders / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009025:Morpholines / Q000494:pharmacology; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D011485:Protein Binding; D011971:Receptors, Immunologic; D015398:Signal Transduction; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D000071176:Signaling Lymphocytic Activation Molecule Family; D000077191:Wortmannin; D014960:X Chromosome
chemical_list: D000730:Androstadienes; D015703:Antigens, CD; D002352:Carrier Proteins; D002867:Chromones; D004791:Enzyme Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011971:Receptors, Immunologic; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D000071176:Signaling Lymphocytic Activation Molecule Family; D000077191:Wortmannin; C084093:CD244 protein, human; C114953:SH2D1A protein, human; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one