title: Identification of Fyn as the binding partner for the WASP N-terminal domain in T cells.
abstract: Wiskott-Aldrich syndrome protein (WASP) plays important roles in TCR signaling. In transgenic (Tg) mice, over-expression of the WASP N-terminal region (exons 1-5) including the enabled/vasodilator-stimulated phosphoprotein (Ena/VASP) homology 1 (EVH1) domain and anti-WASP-EVH1 single-chain variable fragment (scFv) intracellular expressed antibodies (intrabodies) impairs IL-2 production in activated T cells. However, it largely remains unknown that how this domain transduces TCR signaling. Here, we demonstrate for the first time that the WASP N-terminal domain specifically associates with the Fyn SH3 domain; the interaction was uncovered by screening a λgt11 cDNA expression library obtained from the mouse T-cell line KKF. The interaction between Fyn and WASP was inhibited by over-expression of the WASP N-terminal domain and anti-WASP-EVH1 scFv intrabodies in gene-transfected NIH3T3 cells and T cells derived from these Tg mice. WASP-interacting protein binding to the EVH1 domain of WASP was also inhibited in these Tg mice T cells. Furthermore, tyrosine phosphorylation of WASP and nuclear translocation of nuclear factor of activated T cells following TCR stimulation was severely inhibited by over-expression of the WASP N-terminal domain. These observations strongly suggest that the WASP N-terminal domain plays a pivotal role in the TCR signaling cascade by binding to Fyn.
authors.affiliation: Transgenic Animal Research Center, National Institute of Agrobiological Sciences, 1-2 Ohwashi, Tsukuba, Ibaraki 305-8634, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sato
authors.forename: Ryoko
authors.initials: R
authors.lastname: Sawahata
authors.forename: Takato
authors.initials: T
authors.lastname: Takenouchi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitani
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D015870:Gene Expression; D005786:Gene Expression Regulation / Q000276:immunology; D007376:Interleukin-2 / Q000096:biosynthesis; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism; D050778:NFATC Transcription Factors / Q000378:metabolism; D041681:NIH 3T3 Cells; D010766:Phosphorylation / Q000235:genetics / Q000276:immunology; D011485:Protein Binding / Q000502:physiology; D051076:Proto-Oncogene Proteins c-fyn / Q000235:genetics / Q000378:metabolism*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D051316:Wiskott-Aldrich Syndrome Protein / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D002352:Carrier Proteins; D003598:Cytoskeletal Proteins; D007376:Interleukin-2; D046912:Multiprotein Complexes; D050778:NFATC Transcription Factors; D011948:Receptors, Antigen, T-Cell; D011993:Recombinant Fusion Proteins; C491671:Waspip protein, mouse; D051316:Wiskott-Aldrich Syndrome Protein; D014443:Tyrosine; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D020928:Mitogen-Activated Protein Kinases