Vav3 mediates receptor protein tyrosine kinase signaling, regulates GTPase activity, modulates cell morphology, and induces cell transformation.
A recently reported new member of the Vav family proteins, Vav3 has been identified as a Ros receptor protein tyrosine kinase (RPTK) interacting protein by yeast two-hybrid screening. Northern analysis shows that Vav3 has a broad tissue expression profile that is distinct from those of Vav and Vav2. Two species of Vav3 transcripts, 3.4 and 5.4 kb, were detected with a differential expression pattern in various tissues. Transient expression of Vav in 293T and NIH 3T3 cells demonstrated that ligand stimulation of several RPTKs (epidermal growth factor receptor [EGFR], Ros, insulin receptor [IR], and insulin-like growth factor I receptor [IGFR]) led to tyrosine phosphorylation of Vav3 and its association with the receptors as well as their downstream signaling molecules, including Shc, Grb2, phospholipase C (PLC-gamma), and phosphatidylinositol 3 kinase. In vitro binding assays using glutathione S-transferase-fusion polypeptides containing the GTPase-binding domains of Rok-alpha, Pak, or Ack revealed that overexpression of Vav3 in NIH 3T3 cells resulted in the activation of Rac-1 and Cdc42 whereas a deletion mutant lacking the N-terminal calponin homology and acidic region domains activated RhoA and Rac-1 but lost the ability to activate Cdc42. Vav3 induced marked membrane ruffles and microspikes in NIH 3T3 cells, while the N-terminal truncation mutants of Vav3 significantly enhanced membrane ruffle formation but had a reduced ability to induce microspikes. Activation of IR further enhanced the ability of Vav3 to induce membrane ruffles, but IGFR activation specifically promoted Vav3-mediated microspike formation. N-terminal truncation of Vav3 activated its transforming potential, as measured by focus-formation assays. We conclude that Vav3 mediates RPTK signaling and regulates GTPase activity, its native and mutant forms are able to modulate cell morphology, and it has the potential to induce cell transformation.
Zeng
L
L
Department of Microbiology, Mount Sinai School of Medicine, New York, New York 10029, USA.
Sachdev
P
P
Yan
L
L
Chan
J L
JL
Trenkle
T
T
McClelland
M
M
Welsh
J
J
Wang
L H
LH
D016475:3T3 Cells; D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D018797:Cell Cycle Proteins; D002460:Cell Line; D048429:Cell Size; D002471:Cell Transformation, Neoplastic; D016895:Culture Media, Serum-Free; D051380:GRB2 Adaptor Protein; D020662:Guanine Nucleotide Exchange Factors; D006801:Humans; D007668:Kidney / Q000196:embryology; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D051567:Proto-Oncogene Proteins c-vav; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D017451:Receptors, Somatomedin / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D020798:Two-Hybrid System Techniques; D010738:Type C Phospholipases / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D018797:Cell Cycle Proteins; D016895:Culture Media, Serum-Free; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C495949:Grb2 protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D017451:Receptors, Somatomedin; D011993:Recombinant Fusion Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; C528034:Shc1 protein, mouse; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; C496621:VAV3 protein, human; C496622:Vav3 protein, mouse; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human; D020794:Receptor Protein-Tyrosine Kinases; C483813:Ros1 protein, mouse; D010738:Type C Phospholipases; D020741:rho GTP-Binding Proteins