title: LAT-mediated signaling in CD4+CD25+ regulatory T cell development.
abstract: Engagement of the T cell receptor for antigen (TCR) induces formation of signaling complexes mediated through the transmembrane adaptor protein, the linker for activation of T cells (LAT). LAT plays an important role in T cell development, activation, and homeostasis. A knock-in mutation at Tyr136, which is the phospholipase C (PLC)-gamma1-binding site in LAT, leads to a severe autoimmune disease in mice. In this study, we show that CD4+CD25+ T reg cells that expressed Foxp3 transcription factor were nearly absent in both thymus and peripheral lymphoid organs of LAT(Y136F) mice. This defect was not a result of the autoimmune environment as LAT(Y136F) T reg cells also failed to develop in healthy LAT-/- mice that received mixed wild-type and LAT(Y136F) bone marrow cells. Moreover, adoptive transfer of normal CD4+CD25+ T reg cells protected neonatal LAT(Y136F) mice from developing this disease. These T reg cells effectively controlled expansion of CD4+ T cells in LAT(Y136F) mice likely via granzymes and/or TGF-beta-mediated suppression. Furthermore, ectopic expression of Foxp3 conferred a suppressive function in LAT(Y136F) T cells. Our data indicate that the LAT-PLC-gamma1 interaction plays a critical role in Foxp3 expression and the development of CD4+CD25+ T reg cells.
authors.affiliation: Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
authors.forename: Surapong
authors.initials: S
authors.lastname: Koonpaew
authors.forename: Shudan
authors.initials: S
authors.lastname: Shen
authors.forename: Lawrence
authors.initials: L
authors.lastname: Flowers
authors.forename: Weiguo
authors.initials: W
authors.lastname: Zhang
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000276:immunology*; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D051858:Forkhead Transcription Factors / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008822:Mice, Transgenic; D010750:Phosphoproteins / Q000235:genetics / Q000276:immunology*; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D016176:T-Lymphocyte Subsets / Q000276:immunology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; C491734:Lat protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell