Platelet-derived growth factor-induced p21ras-mediated signaling is independent of platelet-derived growth factor receptor interaction with GTPase-activating protein or phosphatidylinositol-3-kinase.
Stimulation with platelet-derived growth factor (PDGF) results in the association of several SH2 domain-containing proteins with the activated PDGF receptor, including GAP, a GTPase-activating protein of p21ras, and phosphatidylinositol-3-kinase (PI-3K). To investigate the role of GAP-PI-3K receptor interaction in p21ras signaling, we have used cell lines expressing mutant PDGF receptors that either are impaired in GAP binding or fail to bind both GAP and PI-3K. In these cell lines, PDGF treatment resulted in activation of extracellular signal-regulated kinase 2 (ERK2), which could be blocked by the expression of a dominant-negative mutant of p21ras (p21ras(asn17)), indicating that these mutations in the PDGF receptor do not abolish p21ras-mediated activation of ERK2. In addition, the PDGF-induced increase in levels of p21rasGTP, as measured either in intact cells or in permeabilized cells, appears to be normal in the cell lines expressing the mutant PDGF receptors. These results indicate that binding of GAP and/or PI-3K to the PDGF receptor is not necessary for PDGF-induced p21ras activation and p21ras-mediated signaling to ERK2. We also show that, in contrast to the activation of ERK2, PDGF-induced GAP and PI-3K interaction with the PDGF receptor are not inhibited by p21ras(asn17) expression, indicating that these interactions do not require p21ras activation.
Laboratory for Physiological Chemistry, Utrecht, The Netherlands.
B M
BM
Burgering
E
E
Freed
L
L
van der Voorn
F
F
McCormick
J L
JL
Bos
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000187:drug effects; D002460:Cell Line; D020690:GTPase-Activating Proteins; D006150:Guanine Nucleotides / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism*; D016283:Proto-Oncogene Proteins p21(ras) / Q000187:drug effects / Q000502:physiology*; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D020703:ras GTPase-Activating Proteins
D020690:GTPase-Activating Proteins; D006150:Guanine Nucleotides; D010982:Platelet-Derived Growth Factor; D011506:Proteins; D020703:ras GTPase-Activating Proteins; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D017479:Receptors, Platelet-Derived Growth Factor; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019950:Mitogen-Activated Protein Kinase 1; D016283:Proto-Oncogene Proteins p21(ras)