Granulocyte-macrophage colony-stimulating factor induces the transcriptional activation of egr-1 through a protein kinase A-independent signaling pathway.
Granulocyte-macrophage colony-stimulating factor (GM-CSF) rapidly and transiently induces the transcriptional activation of the early growth response gene-1 (egr-1) in the human factor-dependent myeloid leukemic cell line, TF-1. We previously demonstrated that the cAMP response element (CRE) is required for GM-CSF-induced egr-1 expression and that phosphorylation of CREB on serine 133 plays a critical role during GM-CSF signal transduction. To determine whether GM-CSF activates signaling pathways through a protein kinase A-dependent or -independent pathway, we measured cAMP levels following GM-CSF or forskolin treatment of TF-1 cells. Forskolin but not GM-CSF stimulation resulted in an increase in cAMP levels. Transient transfection assays with TF-1 cells were also performed with a -116-nucleotide egr-1 promoter construct and the protein kinase inhibitor, PKI. Although PKI inhibited forskolin induction of the -116-nucleotide construct, it did not affect GM-CSF stimulation of this construct. In the present study, we demonstrated that GM-CSF induces egr-1 expression through a protein kinase A-independent pathway.
Gwynne Hazen Cherry Memorial Laboratories, Department of Pediatrics, UCLA School of Medicine 90095-1752, USA.
A
A
Wong
K M
KM
Sakamoto
D002460:Cell Line; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D051766:Early Growth Response Protein 1; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D017874:Immediate-Early Proteins; D007700:Kinetics; D007951:Leukemia, Myeloid; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000494:pharmacology; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis*; D015533:Transcriptional Activation / Q000187:drug effects*; D014162:Transfection; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers; D001616:beta-Galactosidase / Q000096:biosynthesis
D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D004791:Enzyme Inhibitors; D017874:Immediate-Early Proteins; D011994:Recombinant Proteins; D014157:Transcription Factors; D005576:Colforsin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D001616:beta-Galactosidase