Transcriptional regulation of plasminogen activator inhibitor-1 expression in human synovial fibroblasts by prostaglandin E2: mediation by protein kinase A and role of interleukin-1.
Differential expression of PAI-1 in connective tissues has been associated etiologically with some forms of arthritis. Our objective was to delineate the mechanisms by which PGE2 and IL-1 beta, inflammatory mediators commonly found at sites of inflammation, regulate the expression and synthesis of PAI-1 in human synoviocytes. PGE2 (and PGE1) inhibited PAI-1 mRNA expression and secretion in a dose-dependent manner with an IC50 (for antigen secretion) of 4.6 x 10(-10) M and 8.7 x 10(-10) M, respectively. Cyclic AMP agonists forskolin, Sp-cAMP, and IBMX mimic the effects of the PGEs. rhIL-1 beta stimulated the secretion of PAI-1 in a dose-dependent fashion under basal culture conditions; the effect was reversed by actinomycin D and the protein kinase inhibitors H7 and staurosporine but not KT-5720. PMA, an activator of protein kinase C, transiently increased (maximum 3 h) the expression of PAI-1 mRNA by approximately 10-fold, especially the 3.2 kb species. However, there was no significant increase in PAI-1 antigen secreted into the culture medium after PMA (100-300 nM) treatment. The half-life (t1/2) of PAI-1 mRNA, both the 3.2 and 2.2 transcripts was about 9.6 h (mean n = 3) and PGE2 has no affect on the stability of both messages. PGE2 reduced the rate of PAI-1 gene transcription as judged by run-off assays. The NSAID naproxen (30 micrograms/ml) induced the expression of PAI-1 mRNA over basal levels and super-induced the inhibitor's expression above rhIL-1 beta stimulated levels. Our results suggest that PGE2 suppresses PAI-1 expression and synthesis by activation of the cAMP/PKA system and inhibition of the rate of gene transcription. Data concerning the activation of PKC suggest that the expression, synthesis and release of the PAI-1 may be differentially regulated in normal human synoviocytes.
DiBattista
J A
JA
Department of Medicine, University of Montreal, Canada.
Martel-Pelletier
J
J
Morin
N
N
Jolicoeur
F C
FC
Pelletier
J P
JP
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D001769:Blood; D002102:Cadaver; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003470:Culture Media; D000242:Cyclic AMP / Q000031:analogs & derivatives; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology*; D005347:Fibroblasts / Q000201:enzymology; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007375:Interleukin-1 / Q000502:physiology*; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics*; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger / Q000378:metabolism; D013583:Synovial Membrane / Q000201:enzymology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic
D003470:Culture Media; D007375:Interleukin-1; D017395:Plasminogen Activator Inhibitor 1; D047428:Protein Kinase Inhibitors; D012333:RNA, Messenger; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D015056:1-Methyl-3-isobutylxanthine