Proto-oncogene products Vav and c-Cbl are involved in the signal transduction through Grb2/Ash in hematopoietic cells.
Grb2/Ash is composed of one SH2 and two SH3 domains and functions as an adapter linking tyrosine kinase receptors and Ras in fibroblasts. We have investigated the nature of proteins interacting with Grb2/Ash in hematopoietic cells. The product of the vav proto-oncogene (Vav) is expressed exclusively in hematopoietic cells and has guanine nucleotide exchange activity. Here we report that granulocyte/macrophage-colony- stimulating factor (GM-CSF), interleukin-3, and erythropoietin (Epo) induce rapid and transient tyrosine phosphorylation of Vav and that Vav is constitutively associated with the SH3 domain of Grb2/Ash in a human leukemia cell line UT-7. These data implicate Vav in a signaling pathway leading to activation of Ras or Ras-related proteins in hematopoietic cells. Furthermore, we have shown that the proto-oncogene c-cbl product (c-Cbl) is also tyrosine-phosphorylated by stimulation with GM-CSF or Epo and is constitutively associated with the SH3 domain of Grb2/Ash in UT-7. However, we could not find the homologous regions with guanine nucleotide exchange factors or GTPase-activating proteins in the c-cbl gene. Therefore, Grb2/Ash might also transduce a signal that is different from the signal leading to the small-G protein regulation.
Hanazono
Y
Y
Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
Odai
H
H
Sasaki
K
K
Iwamatsu
A
A
Yazaki
Y
Y
Hirai
H
H
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins; D004921:Erythropoietin / Q000494:pharmacology; D051380:GRB2 Adaptor Protein; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology; D006412:Hematopoietic Stem Cells / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011485:Protein Binding; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050721:Proto-Oncogene Proteins c-cbl; D051567:Proto-Oncogene Proteins c-vav; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases; D018631:ras Proteins / Q000378:metabolism; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D007377:Interleukin-3; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D051567:Proto-Oncogene Proteins c-vav; D011956:Receptors, Cell Surface; C496618:VAV1 protein, human; D004921:Erythropoietin; D016179:Granulocyte Colony-Stimulating Factor; D014443:Tyrosine; D050721:Proto-Oncogene Proteins c-cbl; D044767:Ubiquitin-Protein Ligases; D011505:Protein-Tyrosine Kinases; D018631:ras Proteins; C067419:CBL protein, human