title: Knock-in mutation of the distal four tyrosines of linker for activation of T cells blocks murine T cell development.
abstract: The integral membrane adapter protein linker for activation of T cells (LAT) performs a critical function in T cell antigen receptor (TCR) signal transduction by coupling the TCR to downstream signaling pathways. After TCR engagement, LAT is tyrosine phosphorylated by ZAP-70 creating docking sites for multiple src homology 2-containing effector proteins. In the Jurkat T cell line, the distal four tyrosines of LAT bind PLCgamma-1, Grb2, and Gads. Mutation of these four tyrosine residues to phenylalanine (4YF) blocked TCR-mediated calcium mobilization, Erk activation, and nuclear factor (NF)-AT activation. In this study, we examined whether these four tyrosine residues were essential for T cell development by generating LAT "knock-in" mutant mice that express the 4YF mutant protein under the control of endogenous LAT regulatory sequences. Significantly, the phenotype of 4YF knock-in mice was identical to LAT(-/)- (null) mice; thymocyte development was arrested at the immature CD4(-)CD8(-) stage and no mature T cells were present. Knock-in mice expressing wild-type LAT protein, generated by a similar strategy, displayed a normal T cell developmental profile. These results demonstrate that the distal four tyrosine residues of LAT are essential for preTCR signaling and T cell development in vivo.
authors.affiliation: Laboratory of Cellular and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA. connies@helix.nih.gov
authors.forename: C L
authors.initials: CL
authors.lastname: Sommers
authors.forename: R K
authors.initials: RK
authors.lastname: Menon
authors.forename: A
authors.initials: A
authors.lastname: Grinberg
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: L E
authors.initials: LE
authors.lastname: Samelson
authors.forename: P E
authors.initials: PE
authors.lastname: Love
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D002454:Cell Differentiation; D017931:DNA Primers / Q000235:genetics; D008213:Lymphocyte Activation; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D010641:Phenotype; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics* / Q000276:immunology*; D010766:Phosphorylation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D017931:DNA Primers; C491734:Lat protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine