Ras-dependent activation of MAP kinase pathway mediated by G-protein beta gamma subunits.
Mitogen-activated protein kinases, MAP kinases or ERKs (extracellular signal-regulated kinases) are rapidly stimulated by growth-promoting factors acting on a variety of cell-surface receptors. In turn, ERKs phosphorylate and regulate key intracellular enzymes and transcription factors involved in the control of cellular proliferation. The tyrosine-kinase class of growth-factor receptors transmits signals to ERKs in a multistep process that involves Ras and a limited number of defined molecules. In contrast, ERK activation by G-protein-coupled receptors is poorly understood, as is the role of ras in this signalling pathway. We have explored in COS-7 cells the mechanism of ERKs activation by m1 and m2 muscarinic receptors, typical examples of receptors coupled through Gq proteins to induce phosphatidylinositol hydrolysis and to G(i) proteins to inhibit adenylyl cyclase, respectively. Here we present evidence that ERK activation is mediated by beta gamma subunits of heterotrimeric G proteins acting on a ras-dependent pathway.
Crespo
P
P
Molecular Signalling Unit, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Xu
N
N
Simonds
W F
WF
Gutkind
J S
JS
D037361:Adenylate Cyclase Toxin; D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D011976:Receptors, Muscarinic / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D010716:Phosphatidylinositols; D011976:Receptors, Muscarinic; D010566:Virulence Factors, Bordetella; D004815:Epidermal Growth Factor; D002217:Carbachol; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D019950:Mitogen-Activated Protein Kinase 1; D019204:GTP-Binding Proteins; D015689:Oncogene Protein p21(ras); D013755:Tetradecanoylphorbol Acetate