title: The kinase Itk and the adaptor TSAd change the specificity of the kinase Lck in T cells by promoting the phosphorylation of Tyr192.
abstract: The substrate specificity of Src family kinases (SFKs) is partly determined by their Src homology 2 (SH2) domains. Thus, transient alterations in the SH2 domain of SFKs might change their binding partners and affect intracellular signaling pathways. Lck is an SFK that is central to the initiation of T cell activation in response to ligand binding to the T cell receptor (TCR) and is also critical for later signaling processes. The kinase activity of Lck requires both the phosphorylation of an activating tyrosine residue and the dephosphorylation of an inhibitory tyrosine residue. We found that a third conserved tyrosine phosphorylation site (Tyr(192)) within the SH2 domain of Lck was required for proper T cell activation and formation of cell-cell conjugates between T cells and antigen-presenting cells. Through phosphopeptide arrays and biochemical assays, we identified several regulators of the actin cytoskeleton that preferentially bound to Lck phosphorylated at Tyr(192) compared to Lck that was not phosphorylated at this site. Two of these phosphorylation-dependent binding partners, the kinase Itk (interleukin-2-inducible Tec kinase) and the adaptor protein TSAd (T cell-specific adaptor), promoted the TCR-dependent phosphorylation of Lck at Tyr(192). Our data suggest that phosphorylation transiently alters SH2 domain specificity and provide a potential mechanism whereby SFKs may be rewired from one signaling program to another to enable appropriate cell activation.
authors.affiliation: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway. stine.granum@medisin.uio.no anne.spurkland@medisin.uio.no.
authors.forename: Stine
authors.initials: S
authors.lastname: Granum
authors.affiliation: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
authors.forename: Vibeke
authors.initials: V
authors.lastname: Sundvold-Gjerstad
authors.affiliation: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
authors.forename: Ramakrishna Prabhu
authors.initials: RP
authors.lastname: Gopalakrishnan
authors.affiliation: Department of Neurology, Oslo University Hospital Ullevål, 0424 Oslo, Norway.
authors.forename: Tone
authors.initials: T
authors.lastname: Berge
authors.affiliation: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
authors.forename: Lise
authors.initials: L
authors.lastname: Koll
authors.affiliation: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway.
authors.forename: Greger
authors.initials: G
authors.lastname: Abrahamsen
authors.affiliation: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Ås, Norway.
authors.forename: Morten
authors.initials: M
authors.lastname: Sørlie
authors.affiliation: Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo, 0317 Oslo, Norway. stine.granum@medisin.uio.no anne.spurkland@medisin.uio.no.
authors.forename: Anne
authors.initials: A
authors.lastname: Spurkland
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000276:immunology*; D000818:Animals; D000938:Antigen-Presenting Cells / Q000166:cytology / Q000276:immunology; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000235:genetics / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D010766:Phosphorylation / Q000235:genetics / Q000276:immunology; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000276:immunology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013379:Substrate Specificity / Q000235:genetics / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology*; D014443:Tyrosine / Q000235:genetics / Q000276:immunology; D018909:src Homology Domains / Q000235:genetics / Q000276:immunology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D011948:Receptors, Antigen, T-Cell; C405691:SH2D2A protein, human; C402726:Sh2d2a protein, mouse; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); C080813:emt protein-tyrosine kinase