Stimulation of membrane ruffling and MAP kinase activation by distinct effectors of RAS.
The RAS guanine nucleotide binding proteins activate multiple signaling events that regulate cell growth and differentiation. In quiescent fibroblasts, ectopic expression of activated H-RAS (H-RASV12, where V12 indicates valine-12) induces membrane ruffling, mitogen-activated protein (MAP) kinase activation, and stimulation of DNA synthesis. A mutant of activated H-RAS, H-RASV12C40 (where C40 indicates cysteine-40), was identified that was defective for MAP kinase activation and stimulation of DNA synthesis, but retained the ability to induce membrane ruffling. Another mutant of activated H-RAS, H-RASV12S35 (where S35 indicates serine-35), which activates MAP kinase, was defective for stimulation of membrane ruffling and induction of DNA synthesis. Expression of both mutants resulted in a stimulation of DNA synthesis that was comparable to that induced by H-RASV12. These results indicate that membrane ruffling and activation of MAP kinase represent distinct RAS effector pathways and that input from both pathways is required for the mitogenic activity of RAS.
Joneson
T
T
Department of Molecular Genetics and Microbiology, State University of New York at Stony Brook 11794, USA.
White
M A
MA
Wigler
M H
MH
Bar-Sagi
D
D
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000648:ultrastructure*; D004247:DNA / Q000096:biosynthesis; D004789:Enzyme Activation; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism; D008845:Microinjections; D009154:Mutation; D010957:Plasmids; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D051381:Rats; D015398:Signal Transduction; D020744:rac GTP-Binding Proteins; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
D011518:Proto-Oncogene Proteins; D004247:DNA; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D018631:ras Proteins