Proto-oncoprotein Vav interacts with c-Cbl in activated thymocytes and peripheral T cells.
The molecular adapter c-Cbl is rapidly tyrosine phosphorylated following stimulation through the TCR and associates with Src homology domain-2 (SH2)/SH3 domain-containing adapters such as Grb2, Crk, and Crk-L, which interact with guanine nucleotide exchange factors specific for the Ras family. This suggests that c-Cbl may link TCR activation to molecules that regulate GTP binding proteins. The SH2/SH3-containing protein Vav also contains a guanine nucleotide exchange factor domain, and Vav has a crucial role in thymocyte development and activation of peripheral T cells following stimulation through the TCR. Here we show that Vav and c-Cbl form inducible molecular complexes in TCR-activated murine thymocytes and peripheral T cells as well as pervanadate-treated T cells. Vav/c-Cbl interactions are also detectable in freshly isolated T cells from gene-targeted mice that lack the T cell-specific inhibitory receptor CTLA-4, in which c-Cbl is hyperphosphorylated on tyrosine residues. The interaction between Vav and c-Cbl is directly mediated via the SH2 domain of Vav and is dependent on tyrosine phosphorylation of c-Cbl. In addition, we show that the conserved motif Y699 MTP present in c-Cbl is the binding site for the Vav SH2 domain in vitro. These data imply that c-Cbl is a molecular adapter that regulates the function of Vav in thymocytes and peripheral T cells.
Marengère
L E
LE
Amgen Institute, and Department of Medical Biophysics, University of Toronto, Ontario, Canada.
Mirtsos
C
C
Kozieradzki
I
I
Veillette
A
A
Mak
T W
TW
Penninger
J M
JM
D000818:Animals; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D051379:Mice; D011518:Proto-Oncogene Proteins / Q000276:immunology*; D050721:Proto-Oncogene Proteins c-cbl; D051567:Proto-Oncogene Proteins c-vav; D015398:Signal Transduction / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology; D044767:Ubiquitin-Protein Ligases
D018797:Cell Cycle Proteins; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; C496618:VAV1 protein, human; C496619:Vav1 protein, mouse; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; C067419:CBL protein, human; C493849:Cbl protein, mouse