Signal transduction of human interleukin 3 and granulocyte-macrophage colony-stimulating factor through serine and tyrosine phosphorylation.
To elucidate the rapid events in signal transduction of human granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin 3 (IL 3), we examined phosphorylation of proteins on both serine and tyrosine residues in a cytokine-stimulated human myeloid cell line. We found increases in tyrosine phosphorylation within 30 s of stimulation with GM-CSF or IL 3, with peak responses occurring within 2 min. IL 3 and GM-CSF also induced serine phosphorylation, though 10 min of stimulation was required for maximum phosphate incorporation. Interestingly, both IL 3 and GM-CSF stimulated phosphate incorporation in identical substrates, a 68 kDa seryl-phosphoprotein (p68) and a 140 kDa tyrosyl-phosphoprotein (p140). Treatment of AML 193 cells with phorbol myristate acetate resulted in serine phosphorylation of p68; however, p140 was not phosphorylated on tyrosine. Depletion of protein kinase C isoenzymes with high concentrations of phorbol myristate acetate resulted in p68 phosphorylation, which was not further increased by IL 3 or GM-CSF. In contrast, cytokine-induced phosphorylation on tyrosine of p140 was observed after protein kinase C depletion. These data demonstrate the co-ordinate yet independent serine and tyrosine phosphorylation in IL 3- and GM-CSF-treated human myeloid cells, and thus suggest a common set of protein kinases stimulated by each separate ligand.
Laboratory of Molecular Immunoregulation, National Cancer Institute, Frederick Cancer Research Facility, MD 21701-1013.
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D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology*; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism; D010768:Phosphoserine / Q000378:metabolism*; D019000:Phosphotyrosine; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000378:metabolism
D007377:Interleukin-3; D007527:Isoenzymes; D010710:Phosphates; D010768:Phosphoserine; D019000:Phosphotyrosine; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate