Granulocyte-macrophage colony-stimulating factor and interleukin-3 induce rapid phosphorylation and activation of the proto-oncogene Raf-1 in a human factor-dependent myeloid cell line.
The product of the c-raf-1 proto-oncogene, Raf-1, is a 74,000-dalton cytoplasmic serine/threonine protein kinase that has been implicated as an intermediate in signal transduction mechanisms. In the human factor-dependent myeloid cell line MO7, both granulocyte-macrophage colony stimulating factor (GM-CSF) and interleukin-3 (IL-3) were found to induce rapid, dose-dependent phosphorylation of Raf-1, which resulted in altered Raf-1 mobility in sodium dodecyl sulfate-polyacrylamide gels. The increase in phosphorylation was due primarily to an increase in phosphoserine, with only a minor component (less than 2%) of phosphotyrosine. PMA (12-phorbol 13-myristic acid) also induced Raf-1 phosphorylation in MO7 cells, but the resulting alteration in electrophoretic mobility was different than that observed after GM-CSF or IL-3. GM-CSF and IL-3 rapidly and transiently increased Raf-1 kinase activity using Histone H1 as a substrate in an immune complex kinase assay in vitro. These results suggest that phosphorylation of Raf-1 could play a role in some aspect of GM-CSF and IL-3 signal transduction.
Kanakura
Y
Y
Dana-Farber Cancer Institute, Boston, MA 02115.
Druker
B
B
Wood
K W
KW
Mamon
H J
HJ
Okuda
K
K
Roberts
T M
TM
Griffin
J D
JD
D002460:Cell Line; D004988:Ethers, Cyclic / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007377:Interleukin-3 / Q000494:pharmacology*; D019319:Okadaic Acid; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011233:Precipitin Tests; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf; D011956:Receptors, Cell Surface / Q000502:physiology; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014638:Vanadates / Q000494:pharmacology
D004988:Ethers, Cyclic; D007377:Interleukin-3; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D010768:Phosphoserine; D019319:Okadaic Acid; D014638:Vanadates; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019908:Proto-Oncogene Proteins c-raf; D013755:Tetradecanoylphorbol Acetate