Hepatocyte growth factor/scatter factor stimulates the Ras-guanine nucleotide exchanger.
Hepatocyte growth factor/scatter factor (HGF/SF) induces mitogenesis and cell dissociation upon binding to the protein-tyrosine kinase receptor encoded by the MET proto-oncogene (p190MET). The signal transduction pathways downstream from the receptor activation are largely unknown. We show that HGF/SF activates Ras protein. HGF/SF stimulation of metabolically labeled A549 cells raised the amount of Ras-bound radiolabeled guanine nucleotides by over 5-fold. Furthermore, following HGF/SF stimulation of these cells, 50% of Ras was in the GTP-bound active state. The uptake by Ras of radiolabeled GTP was also increased by 5-fold following HGF/SF stimulation in digitonin-permeabilized A549 cells. Moreover, HGF/SF treatment of A549 cells leads to stimulation of the cytosolic Ras-guanine nucleotide exchange activity, measured as accelerated release of [3H]GDP from purified recombinant Ras protein in vitro, in a dose- and time-dependent manner. Likewise, treatment with the protein-tyrosine kinase inhibitor 3-(1',4'-dihydroxytetralyl)methylene-2-oxindole of GTL-16 cells (featuring a p190MET receptor constitutively active) significantly decreased the cytosolic Ras-guanine nucleotide exchange activity. These data demonstrate that HGF/SF activates Ras protein by shifting the equilibrium toward the GTP-bound state and increases the uptake of guanine nucleotides by Ras, through mechanism(s) including the activation of a Ras-guanine nucleotide exchanger.
Department of Biomedical Sciences and Oncology, University of Torino Medical School, Italy.
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D001692:Biological Transport / Q000187:drug effects; D002460:Cell Line; D020690:GTPase-Activating Proteins; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006160:Guanosine Triphosphate / Q000378:metabolism*; D017228:Hepatocyte Growth Factor / Q000494:pharmacology*; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D007700:Kinetics; D008175:Lung Neoplasms; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D011519:Proto-Oncogenes; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D013764:Tetrahydronaphthalenes / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D020703:ras GTPase-Activating Proteins
D020690:GTPase-Activating Proteins; D007211:Indoles; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D013764:Tetrahydronaphthalenes; D020703:ras GTPase-Activating Proteins; D006153:Guanosine Diphosphate; D017228:Hepatocyte Growth Factor; D006160:Guanosine Triphosphate; D011505:Protein-Tyrosine Kinases; D019859:Proto-Oncogene Proteins c-met; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)