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Vav is a GTP/GDP exchange factor (GEF) for members of the Rho-family of GTPases that is rapidly tyrosine-phosphorylated after engagement of the T cell receptor (TCR), suggesting that it may transduce signals from the receptor. T cells from mice made Vav-deficient by gene targeting (Vav-/-) fail to proliferate in response to TCR stimulation because they fail to secrete IL-2. We now show that this is due at least in part to the failure to initiate IL-2 gene transcription. Furthermore, we analyze TCR-proximal signaling pathways in Vav-/- T cells and show that despite normal activation of the Lck and ZAP-70 tyrosine kinases, the mutant cells have specific defects in TCR-induced intracellular calcium fluxes, in the activation of extracellular signal-regulated mitogen-activated protein kinases and in the activation of the NF-kappaB transcription factor. Finally, we show that the greatly reduced TCR-induced calcium flux of Vav-deficient T cells is an important cause of their proliferative defect, because restoration of the calcium flux with a calcium ionophore reverses the phenotype.

Type

Journal article

Journal

Proc Natl Acad Sci U S A

Publication Date

16/03/1999

Volume

96

Pages

3035 - 3040

Keywords

Animals, Calcium, Cell Cycle Proteins, GTP Phosphohydrolases, Lymphocyte Specific Protein Tyrosine Kinase p56(lck), Mice, Mutation, NF-kappa B, Protein-Tyrosine Kinases, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-vav, Receptors, Antigen, T-Cell, Signal Transduction, T-Lymphocytes, ZAP-70 Protein-Tyrosine Kinase