Concanavalin A-induced granulocyte-macrophage colony-stimulating factor production in a murine T-cell line is posttranscriptionally controlled.
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic growth factor (HGF) that regulates the proliferation and differentiation of cells of the myeloid lineage. It can be produced by a variety of cells. One of the major sources of GM-CSF is activated T cells, which transiently produce this HGF. We used the EL-4 thymoma cell line as a model system to address the molecular basis for GM-CSF regulation in T cells. Both concanavalin A (ConA) and the phorbol ester, 12-O-tetradecanoylphorbol 13-acetate (TPA) induce GM-CSF expression in EL-4 cells. However, the biological activity of GM-CSF in the supernatants of the TPA-stimulated cells was higher than that of ConA-stimulated cells. To elucidate this difference in biological activity levels, we examined how ConA regulates GM-CSF gene expression in EL-4 cells and compared it to the better-characterized regulation by TPA. Peak mRNA levels of GM-CSF occur 6 h after stimulation with either of these two agents. GM-CSF mRNA levels after ConA treatment are lower and decrease significantly after 10 h compared to TPA treatment, which causes much higher levels that persist for at least 24 h. Neither agent alters GM-CSF gene transcription. Actinomycin D chase experiments show that ConA increases the GM-CSF mRNA half-life from less than 30 to 90 min, whereas TPA prolongs it to greater than 3 h. These results indicate that GM-CSF mRNA induction by ConA (in common with TPA) is regulated predominantly via RNA stabilization and that the difference in prolongation of the mRNA half-life provides the primary explanation for the lower levels of GM-CSF mRNA induced by ConA compared to TPA.
Iwai
Y
Y
Division of Cytokine Biology, Food and Drug Administration, Bethesda, MD 20892.
Bickel
M
M
Cohen
R B
RB
Pluznik
D H
DH
D000818:Animals; D003208:Concanavalin A / Q000494:pharmacology*; D003609:Dactinomycin; D004305:Dose-Response Relationship, Drug; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism*; D006207:Half-Life; D051379:Mice; D012323:RNA Processing, Post-Transcriptional / Q000187:drug effects*; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D012334:RNA, Neoplasm / Q000032:analysis / Q000235:genetics; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013945:Thymoma / Q000378:metabolism / Q000473:pathology; D013953:Thymus Neoplasms / Q000378:metabolism / Q000473:pathology; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured / Q000378:metabolism / Q000473:pathology
D012333:RNA, Messenger; D012334:RNA, Neoplasm; D003208:Concanavalin A; D003609:Dactinomycin; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D013755:Tetradecanoylphorbol Acetate