Association of Bcr-Abl with the proto-oncogene Vav is implicated in activation of the Rac-1 pathway.
Vav is a guanine nucleotide exchange factor for the Rho/Rac family predominantly expressed in hematopoietic cells and implicated in cell proliferation and cytoskeletal organization. The oncogenic tyrosine kinase Bcr-Abl has been shown to activate Rac-1, which is important for Bcr-Abl induced leukemogenesis. Previous studies by Matsuguchi et al. (Matsuguchi, T., ... Inhorn, R. C., Carlesso, N., Xu, G., Druker, B., and Griffin, J. D. (1995) EMBO J. 14, 257-265) describe enhanced phosphorylation of Vav in Bcr-Abl-expressing Mo7e cells yet fail to demonstrate association of the two proteins. Here, we report the identification of a direct complex between Vav and Bcr-Abl in yeast, in vitro and in vivo. Furthermore, we show tyrosine phosphorylation of Vav by Bcr-Abl. Mutational analysis revealed that the SH2 domain and the C-terminal SH3 domain as well as a tetraproline motif directly adjacent to the N-terminal SH3 domain of Vav are important for establishing this phosphotyrosine dependent interaction. Activation of Rac-1 by Bcr-Abl was abrogated by co-expression of the Vav C terminus encoding the SH3-SH2-SH3 domains as a dominant negative construct. Bcr-Abl transduced primary bone marrow from Vav knock-out mice showed reduced proliferation in a culture cell transformation assay compared with wild-type bone marrow. These results suggest, that Bcr-Abl utilizes Vav as a guanine nucleotide exchange factor to activate Rac-1 in a process that involves a folding mechanism of the Vav C terminus. Given the importance of Rac-1 activation for Bcr-Abl-mediated leukemogenesis, this mechanism may be crucial for the molecular pathogenesis of chronic myeloid leukemia and of importance for other signal transduction pathways leading to the activation of Rac-1.
Mesh Terms:
3T3 Cells, Animals, Bone Marrow Cells, Cell Cycle Proteins, Cell Line, DNA, Complementary, Electrophoresis, Polyacrylamide Gel, Enzyme Activation, Fusion Proteins, bcr-abl, Genes, Dominant, Glutathione Transferase, Humans, Immunoblotting, Mice, Mice, Knockout, Phosphorylation, Plasmids, Precipitin Tests, Proline, Protein Binding, Protein Structure, Tertiary, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-vav, Recombinant Fusion Proteins, Retroviridae, Signal Transduction, Temperature, Transfection, Two-Hybrid System Techniques, Tyrosine, rac1 GTP-Binding Protein, src Homology Domains
3T3 Cells, Animals, Bone Marrow Cells, Cell Cycle Proteins, Cell Line, DNA, Complementary, Electrophoresis, Polyacrylamide Gel, Enzyme Activation, Fusion Proteins, bcr-abl, Genes, Dominant, Glutathione Transferase, Humans, Immunoblotting, Mice, Mice, Knockout, Phosphorylation, Plasmids, Precipitin Tests, Proline, Protein Binding, Protein Structure, Tertiary, Proto-Oncogene Proteins, Proto-Oncogene Proteins c-vav, Recombinant Fusion Proteins, Retroviridae, Signal Transduction, Temperature, Transfection, Two-Hybrid System Techniques, Tyrosine, rac1 GTP-Binding Protein, src Homology Domains
J. Biol. Chem.
Date: Apr. 05, 2002
PubMed ID: 11790798
View in: Pubmed Google Scholar
Download Curated Data For This Publication
4811
Switch View:
- Interactions 4