The four distal tyrosines are required for LAT-dependent signaling in FcepsilonRI-mediated mast cell activation.
The linker for activation of T cells (LAT) is an adaptor protein critical for Fc epsilon RI-mediated mast cell activation. LAT is a substrate of the tyrosine kinases activated after TCR and Fc epsilon RI engagement. After phosphorylation of the cytosolic domain of LAT, multiple signaling molecules such as phospholipase C-gamma1, Grb2, and Gads associate with phosphorylated LAT via their SH2 domains. The essential role of the four distal tyrosines in TCR-mediated signaling and T cell development has been demonstrated by experiments using LAT-deficient cell lines and genetically modified mice. To investigate the role of these four tyrosines of LAT in Fc epsilon RI-mediated mast cell activation, bone marrow-derived mast cells from LAT-deficient mice were infected with retroviral vectors designed to express wild-type or mutant LAT. Examination of bone marrow-derived mast cells expressing various tyrosine to phenylalanine mutants in LAT demonstrates a differential requirement for these different binding sites. In these studies, assays of biochemical pathways, degranulation, and cytokine and chemokine release were performed. Finally, the role of these tyrosines was also evaluated in vivo using genetically modified animals. Deletion of all four distal tyrosines, and in particular, loss of the primary phospholipase C-gamma-binding tyrosine had a significant effect on antigen-induced histamine release.
Saitoh
Shin-ichiroh
S
Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892, USA.
Odom
Sandra
S
Gomez
Gregorio
G
Sommers
Connie L
CL
Young
Howard A
HA
Rivera
Juan
J
Samelson
Lawrence E
LE
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology*; D008213:Lymphocyte Activation; D008407:Mast Cells / Q000276:immunology*; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D016296:Mutagenesis; D010750:Phosphoproteins / Q000172:deficiency / Q000235:genetics / Q000276:immunology*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000276:immunology; D011505:Protein-Tyrosine Kinases; D011948:Receptors, Antigen, T-Cell / Q000276:immunology; D017455:Receptors, IgE / Q000737:chemistry / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000276:immunology*; D014443:Tyrosine
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C491734:Lat protein, mouse; D008565:Membrane Proteins; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; D017455:Receptors, IgE; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases