Tyrosine 807 of the v-Fms oncogene product controls cell morphology and association with p120RasGAP.
Expression of the v-fms oncogene of feline sarcoma virus in fibroblasts causes surface exposure of an activated receptor tyrosine kinase, v-Fms, that is autophosphorylated at multiple sites within its cytoplasmic domain. Cellular proteins interacting with this part of v-Fms modulate the mitogenic activity and morphology of the cells. We show here that the tyrosine residue in position 807 (Y-807) of the v-Fms molecule constitutes a major autophosphorylation site. The replacement of this residue by phenylalanine (Y807F mutation) allowed us to functionally dissect v-Fms-specific mitogenic and morphogenic cascades. Cells expressing the mutant v-Fms molecule resembled wild-type (wt) v-Fms-transformed (wt-v-Fms) cells in terms of [3H]thymidine uptake rates and activation of the Ras/Raf-1 mitogenic cascade. Such cells showed, however, a flat morphology and contained intact actin cables and fibronectin network. Our studies indicate that the v-Fms molecule controls cell morphology by a cascade that involves a direct interaction with p120RasGAP and p190RhoGAP: (i) in contrast to wt v-Fms molecules, the Y807F v-Fms protein failed to associate with and phosphorylate p120RasGAP; (ii) tight complexes between p120RasGAP and p190RhoGAP as well as detectable RhoGAP activity were present exclusively in wt-v-Fms cells; and (iii) p190RhoGAP was dispersed throughout the cytoplasm of wt-v-Fms cells, whereas its distribution was restricted to perinuclear regions of cells expressing the mutant v-Fms gene.
Trouliaris
S
S
Institut für Virologie, Justus-Liebig-Universität Giessen, Germany.
Smola
U
U
Chang
J H
JH
Parsons
S J
SJ
Niemann
H
H
Tamura
T
T
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002471:Cell Transformation, Neoplastic; D004261:DNA Replication; D020690:GTPase-Activating Proteins; D016236:Genes, fms; D005982:Glutathione Transferase / Q000096:biosynthesis; D007700:Kinetics; D051379:Mice; D016281:Oncogene Protein gp140(v-fms) / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism*; D009857:Oncogenes; D010649:Phenylalanine; D010957:Plasmids; D017354:Point Mutation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D005253:Sarcoma Viruses, Feline / Q000235:genetics / Q000502:physiology*; D013936:Thymidine / Q000378:metabolism; D014162:Transfection; D014443:Tyrosine; D020703:ras GTPase-Activating Proteins
D020690:GTPase-Activating Proteins; D016281:Oncogene Protein gp140(v-fms); D011506:Proteins; D011993:Recombinant Fusion Proteins; D020703:ras GTPase-Activating Proteins; D014443:Tyrosine; D010649:Phenylalanine; D005982:Glutathione Transferase; D011505:Protein-Tyrosine Kinases; D013936:Thymidine