title: Alternative antigen receptor (TCR) signaling in T cells derived from ZAP-70-deficient patients expressing high levels of Syk.
abstract: ZAP-70-deficient patients present with nonfunctional CD4+ T cells in the periphery. We find that a subset of primary ZAP-70-deficient T cells, expressing high levels of the related protein-tyrosine kinase Syk, can proliferate in vitro. These cells (denoted herein as Syk(hi)/ZAP-70(-) T cells) provide a unique model in which the contribution of Syk to TCR-mediated responses can be explored in a nontransformed background. Importantly, CD3-induced responses, such as tyrosine phosphorylation of cellular substrates (LAT, SLP76, and PLC-gamma1), as well as calcium mobilization, which are defective in T cells expressing neither ZAP-70 nor Syk, are observed in Syk(hi)/ZAP-70(-) T cells. However, Syk(hi)/ZAP-70(-) T cells differ from control T cells with respect to the T cell antigen receptor (TCR)-mediated activation of the MAPK cascades: extracellular signal-regulated kinase activity and recruitment of the JNK and p38 stress-related MAPK pathways are diminished. This distinct phenotype of Syk(hi)/ZAP-70(-) T cells is associated with a profound decrease in CD3-mediated interleukin 2 secretion and proliferation relative to control T cells. Thus, ZAP-70 and Syk appear to play distinct roles in transducing a TCR-mediated signal.
authors.affiliation: Institut de Génétique Moléculaire de Montpellier, CNRS UMR 5535, 1919 Route de Mende, 34293 Montpellier, Cedex 5, France. noraz@igm.cnrs-mop.fr
authors.forename: N
authors.initials: N
authors.lastname: Noraz
authors.forename: K
authors.initials: K
authors.lastname: Schwarz
authors.forename: M
authors.initials: M
authors.lastname: Steinberg
authors.forename: V
authors.initials: V
authors.lastname: Dardalhon
authors.forename: C
authors.initials: C
authors.lastname: Rebouissou
authors.forename: R
authors.initials: R
authors.lastname: Hipskind
authors.forename: W
authors.initials: W
authors.lastname: Friedrich
authors.forename: H
authors.initials: H
authors.lastname: Yssel
authors.forename: K
authors.initials: K
authors.lastname: Bacon
authors.forename: N
authors.initials: N
authors.lastname: Taylor
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D001483:Base Sequence; D017252:CD3 Complex / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000378:metabolism; D002455:Cell Division; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D007376:Interleukin-2 / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases; D019169:Jurkat Cells; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D000072377:Syk Kinase; D010738:Type C Phospholipases / Q000378:metabolism; D051746:ZAP-70 Protein-Tyrosine Kinase
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017252:CD3 Complex; D002352:Carrier Proteins; D004792:Enzyme Precursors; D007376:Interleukin-2; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; C110810:LAT protein, human; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; C092947:SLP-76 signal Transducing adaptor proteins; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases; C000606896:SYK protein, human; D000072377:Syk Kinase; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D002118:Calcium