Activation of the cAMP-dependent signaling pathway downregulates the expression of interleukin-3 and granulocyte-macrophage colony-stimulating factor in activated human T lymphocytes.
Expression of cytokines by T lymphocytes is a highly balanced process, involving stimulatory and inhibitory intracellular signaling pathways. We have examined the modulating effects of the cAMP-dependent signaling pathway on the expression of interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF) in activated human T lymphocytes. 2'-O-dibutyryl-cAMP (db-cAMP), prostaglandin E2 (PGE2), isoproterenol (ISO), and isobutyl-methyl-xantin (IBMX) costimulated with concanavalin A (Con A) or Con A plus the phorbolester phorbol myristate acetate (PMA) inhibited IL-3 and GM-CSF mRNA accumulation compared to the effects of Con A or Con A plus PMA alone. Nuclear run-on experiments revealed that the inhibitory effect of db-cAMP could partially be ascribed to a five-fold reduction in transcription rate of both the IL-3 and GM-CSF gene in the presence of Con A or Con A plus PMA. mRNA stability studies demonstrated that PMA increased the stability of both transcripts. db-cAMP did not affect the stability of IL-3 and GM-CSF mRNAs in Con A activated cells. In contrast, in Con A plus PMA activated cells, db-cAMP significantly reduced the half-life of both transcripts: IL-3 >240 minutes vs. 90 minutes and GM-CSF 90 minutes vs. 60 minutes. Finally, in accordance with the mRNA data, db-cAMP, PGE2, and ISO reduced the secretion of IL-3 and GM-CSF protein in Con A and Con A plus PMA activated cells. In conclusion, these data demonstrate that the protein kinase A (PKA)-dependent signaling pathway is an important regulatory mechanism in controlling IL-3 and GM-CSF gene expression in activated human T lymphocytes.
Borger
P
P
Division of Allergology, Depaartment of Medicine, University of Groningen, The Netherlands.
Kauffman
H F
HF
Vijgen
J L
JL
Postma
D S
DS
Vellenga
E
E
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D015232:Dinoprostone / Q000494:pharmacology; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006207:Half-Life; D006801:Humans; D007377:Interleukin-3 / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007377:Interleukin-3; D012333:RNA, Messenger; D003208:Concanavalin A; D003994:Bucladesine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone; D007545:Isoproterenol; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine