Post-transcriptional regulation of granulocyte-macrophage colony-stimulating factor synthesis in murine T cells.
The granulocyte-macrophage CSF (GM-CSF) gene is known to be controlled at a variety of levels in different cell types. We showed previously that GM-CSF production by lectin or phorbol ester (12-O-tetradecanoyl-phorbol-13-acetate (TPA]-treated T cells was unaffected by cyclosporin A whereas IL-2 and IL-3 expression were. Cyclosporin A is thought to inhibit transcription that suggests that IL-2 and IL-3 are regulated primarily at the transcriptional level while GM-CSF is not. The lack of coordinate gene expression is of particular interest because all three mRNA share the presence of adenosine uridine-rich sequences in the 3' untranslated region and these sequences are believed to act by modulating mRNA stability. We measured the level of GM-CSF mRNA in untreated cells and found it to be extremely low. GM-CSF mRNA levels increased approximately 60-fold within 6 h of TPA-treatment. Nuclear run-on transcription analysis of the same cells showed readily detectable GM-CSF transcription in unstimulated cells that increased less than twofold after TPA treatment. However, IL-2 transcription was insignificant before TPA addition. Actinomycin D chase experiments showed that GM-CSF transcripts in untreated cells have a very short half-life (approximately 45 min) although transcripts in TPA-treated cells have a half-life exceeding 3 h. These findings indicate that GM-CSF production in EL-4 cells treated with TPA is regulated predominantly by modulation of cytoplasmic mRNA half-life.
Bickel
M
M
Division of Cytokine Biology Center for Biologics, Evaluation and Research, Food and Drug Administration, Bethesda, MD 20892.
Cohen
R B
RB
Pluznik
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DH
D000818:Animals; D003115:Colony-Stimulating Factors / Q000096:biosynthesis*; D003513:Cycloheximide / Q000494:pharmacology; D003524:Cyclosporins / Q000494:pharmacology; D004004:Dichlororibofuranosylbenzimidazole / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D006133:Growth Substances / Q000096:biosynthesis*; D006207:Half-Life; D007376:Interleukin-2 / Q000096:biosynthesis; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis; D013601:T-Lymphocytes / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
D003115:Colony-Stimulating Factors; D003524:Cyclosporins; D006133:Growth Substances; D007376:Interleukin-2; D012333:RNA, Messenger; D004004:Dichlororibofuranosylbenzimidazole; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D003513:Cycloheximide; D013755:Tetradecanoylphorbol Acetate