Granulocyte colony-stimulating factor activates protein kinase A in granulocytic but not monocytic precursors or neutrophils.
Granulocyte colony-stimulating factor (G-CSF) regulates survival, proliferation, differentiation, and activation of myeloid cells. G-CSF-R signaling mechanisms other than tyrosine kinase activation have not been documented. We explored the potential involvement of cAMP-dependent protein kinase A (PKA) in G-CSF-R signal transduction. In this report, we provide the first direct evidence of PKA modulation by G-CSF-R. G-CSF treatment of granulocytic precursor cell lines (HL-60, NFS-60, KG-1) resulted in PKA activation, measured by phosphorylation of Kemptide, a peptide substrate. In contrast, the myelomonocytic cell lines (WEHI-3B,U-937) and peripheral blood neutrophils (PMNC) showed a rapid decrease in PKA activity in response to G-CSF. H-89, a specific inhibitor of PKA, blocked G-CSF-induced PKA activation in HL-60 cells but did not affect ligand-induced downmodulation of G-CSF-R. Indomethacin, an inhibitor of the cyclooxygenase pathway and prostaglandin synthesis, did not inhibit PKA induction in G-CSF-treated HL-60 cells. Our results demonstrate the involvement of PKA in G-CSF-R signal transduction and suggest a lineage-restricted, developmental stage-specific regulation of this pathway in myeloid cells.
Deshpande
R V
RV
James Ewing Laboratory of Developmental Hematopoiesis, Program of Cell Biology and Genetics, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA. rajendra@amgen.com
Peterson
R H
RH
Moore
M A
MA
D000818:Animals; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006098:Granulocytes / Q000187:drug effects*; D018922:HL-60 Cells; D006801:Humans; D007457:Iodine Radioisotopes; D009000:Monocytes / Q000187:drug effects*; D009504:Neutrophils / Q000187:drug effects*; D013234:Stem Cells / Q000187:drug effects; D014407:Tumor Cells, Cultured
D004791:Enzyme Inhibitors; D007457:Iodine Radioisotopes; D016179:Granulocyte Colony-Stimulating Factor; D017868:Cyclic AMP-Dependent Protein Kinases