title: SAP-mediated inhibition of diacylglycerol kinase α regulates TCR-induced diacylglycerol signaling.
abstract: Diacylglycerol kinases (DGKs) metabolize diacylglycerol to phosphatidic acid. In T lymphocytes, DGKα acts as a negative regulator of TCR signaling by decreasing diacylglycerol levels and inducing anergy. In this study, we show that upon costimulation of the TCR with CD28 or signaling lymphocyte activation molecule (SLAM), DGKα, but not DGKζ, exits from the nucleus and undergoes rapid negative regulation of its enzymatic activity. Inhibition of DGKα is dependent on the expression of SAP, an adaptor protein mutated in X-linked lymphoproliferative disease, which is essential for SLAM-mediated signaling and contributes to TCR/CD28-induced signaling and T cell activation. Accordingly, overexpression of SAP is sufficient to inhibit DGKα, whereas SAP mutants unable to bind either phospho-tyrosine residues or SH3 domain are ineffective. Moreover, phospholipase C activity and calcium, but not Src-family tyrosine kinases, are also required for negative regulation of DGKα. Finally, inhibition of DGKα in SAP-deficient cells partially rescues defective TCR/CD28 signaling, including Ras and ERK1/2 activation, protein kinase C membrane recruitment, induction of NF-AT transcriptional activity, and IL-2 production. Thus SAP-mediated inhibition of DGKα sustains diacylglycerol signaling, thereby regulating T cell activation, and it may represent a novel pharmacological strategy for X-linked lymphoproliferative disease treatment.
authors: Department of Clinical and Experimental Medicine, University A. Avogadro of Piemonte Orientale, 28100 Novara, Italy. baldanzi@med.unipmn.it
authors: Gianluca
authors: G
authors: Baldanzi
authors: Andrea
authors: A
authors: Pighini
authors: Valentina
authors: V
authors: Bettio
authors: Elena
authors: E
authors: Rainero
authors: Sara
authors: S
authors: Traini
authors: Federica
authors: F
authors: Chianale
authors: Paolo E
authors: PE
authors: Porporato
authors: Nicoletta
authors: N
authors: Filigheddu
authors: Riccardo
authors: R
authors: Mesturini
authors: Shuping
authors: S
authors: Song
authors: Tamas
authors: T
authors: Schweighoffer
authors: Laura
authors: L
authors: Patrussi
authors: Cosima T
authors: CT
authors: Baldari
authors: Xiao-Ping
authors: XP
authors: Zhong
authors: Wim J
authors: WJ
authors: van Blitterswijk
authors: Fabiola
authors: F
authors: Sinigaglia
authors: Kim E
authors: KE
authors: Nichols
authors: Ignacio
authors: I
authors: Rubio
authors: Ornella
authors: O
authors: Parolini
authors: Andrea
authors: A
authors: Graziani
mesh_terms: D015153:Blotting, Western; D019852:Diacylglycerol Kinase / Q000378:metabolism*; D004075:Diglycerides / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology / Q000378:metabolism*; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000276:immunology*; D021381:Protein Transport / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism; D014162:Transfection
chemical_list: D004075:Diglycerides; D047908:Intracellular Signaling Peptides and Proteins; D011948:Receptors, Antigen, T-Cell; C114953:SH2D1A protein, human; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein; D019852:Diacylglycerol Kinase