Minimal requirement of tyrosine residues of linker for activation of T cells in TCR signaling and thymocyte development.
Linker for activation of T cells (LAT) is a membrane-associated adaptor protein that is phosphorylated on multiple tyrosines upon TCR cross-linking. Previous studies show that LAT is essential for TCR-mediated signaling and thymocyte development. In this study, we expressed a series of LAT Tyr to Phe mutants in LAT-deficient J.CaM2.5 cells and examined their tyrosine phosphorylation; association with Grb2, Gads, and phospholipase C (PLC)-gamma1; and function in T cell activation. Our results showed that the five membrane-distal tyrosines were phosphorylated upon T cell activation. Grb2, Gads, and PLC-gamma1 associated with LAT preferentially via different sets of tyrosine residues; however, they failed to interact with LAT mutants containing only one tyrosine. We also determined the minimal requirement of LAT tyrosine residues in T cell activation and thymocyte development. Our results showed that a minimum of three tyrosines is required for LAT to function in T cell activation and thymocyte development. LAT mutants that were capable of binding Grb2 and PLC-gamma1 could reconstitute T cell activation in LAT-deficient cells and thymocyte development in LAT-deficient mice.
Zhu
Minghua
M
Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA.
Janssen
Erin
E
Zhang
Weiguo
W
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002460:Cell Line; D051380:GRB2 Adaptor Protein; D007527:Isoenzymes / Q000378:metabolism; D008213:Lymphocyte Activation / Q000235:genetics; D008565:Membrane Proteins; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D051966:Phospholipase C gamma; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D011485:Protein Binding / Q000235:genetics; D011506:Proteins / Q000378:metabolism / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000502:physiology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000166:cytology / Q000201:enzymology / Q000276:immunology* / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D014161:Transduction, Genetic; D014162:Transfection; D010738:Type C Phospholipases / Q000378:metabolism; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*; D018909:src Homology Domains / Q000235:genetics
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D051380:GRB2 Adaptor Protein; C495949:Grb2 protein, mouse; D007527:Isoenzymes; C491734:Lat protein, mouse; D008565:Membrane Proteins; C498726:Mona protein, mouse; D010750:Phosphoproteins; D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D014443:Tyrosine; D010738:Type C Phospholipases; D051966:Phospholipase C gamma