Persistence of cooperatively stabilized signaling clusters drives T-cell activation.
Antigen recognition triggers the recruitment of the critical adaptor protein SLP-76 to small macromolecular clusters nucleated by the T-cell receptor (TCR). These structures develop rapidly, in parallel with TCR-induced increases in tyrosine phosphorylation and cytosolic calcium, and are likely to contribute to TCR-proximal signaling. Previously, we demonstrated that these SLP-76-containing clusters segregate from the TCR and move towards the center of the contact interface. Neither the function of these clusters nor the structural requirements governing their persistence have been examined extensively. Here we demonstrate that defects in cluster assembly and persistence are associated with defects in T-cell activation in the absence of Lck, ZAP-70, or LAT. Clusters persist normally in the absence of phospholipase C-gamma1, indicating that in the absence of a critical effector, these structures are insufficient to drive T-cell activation. Furthermore, we show that the critical adaptors LAT and Gads localize with SLP-76 in persistent clusters. Mutational analyses of LAT, Gads, and SLP-76 indicated that multiple domains within each of these proteins contribute to cluster persistence. These data indicate that multivalent cooperative interactions stabilize these persistent signaling clusters, which may correspond to the functional complexes predicted by kinetic proofreading models of T-cell activation.
Bunnell
Stephen C
SC
Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, National Institutes of Health, Bethesda, Maryland, USA. Stephen.Bunnell@tufts.edu
Singer
Andrew L
AL
Hong
David I
DI
Jacque
Berri H
BH
Jordan
Martha S
MS
Seminario
Maria-Cristina
MC
Barr
Valarie A
VA
Koretzky
Gary A
GA
Samelson
Lawrence E
LE
D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D004768:Enterotoxins / Q000494:pharmacology; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013601:T-Lymphocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D013816:Thermodynamics
D048868:Adaptor Proteins, Signal Transducing; D004768:Enterotoxins; C110810:LAT protein, human; D008565:Membrane Proteins; C498726:Mona protein, mouse; D010750:Phosphoproteins; D011993:Recombinant Fusion Proteins; C092947:SLP-76 signal Transducing adaptor proteins; C049463:enterotoxin E, Staphylococcal