Prostaglandin E2 Regulates the Level and Stability of Cyclooxygenase-2 mRNA through Activation of p38 Mitogen-activated Protein Kinase in Interleukin-1β-treated Human Synovial Fibroblasts

Abstract

The p38 MAPK mediates transcriptional and posttranscriptional control of cyclooxygenase-2 (COX-2) mRNA following interleukin-1(IL-1)/lipopolysaccharide cellular activation. We explored a positive feedback, prostaglandin E 2 (PGE 2 )-dependent stabilization of COX-2 mRNA mediated by the p38 MAPK cascade in IL-1␤-stimulated human synovial fibroblasts. We observed a rapid (5 min), massive (>30-fold), and sustained (>48 h) increase in COX-2 mRNA, protein, and PGE 2 release following a recombinant human (rh) IL-1␤ signal that was inhibited by NS-398, a COX-2 inhibitor, and SB202190, a selective, cell-permeable p38 MAPK inhibitor. PGE 2 completely reversed NS-398-mediated inhibition but not SB202190-dependent inhibition. The eicosanoid didn't potentiate IL-1␤-induced COX-2 expression nor did it activate COX-2 gene expression in quiescent cells. Transfection experiments with a human COX-2 promoter construct revealed a minor element of p38 MAPK-dependent transcriptional control after IL-1␤ stimulation. p38 MAPK synergized with the cAMP/cAMP-dependent protein kinase cascade to transactivate the COX-2 promoter. When human synovial fibroblasts were activated with rhIL-1␤ for 3-4 h (steady state) followed by washout, the elevated levels of COX-2 mRNA declined rapidly (<2 h) to control levels. If PGE 2 , unlike EP2/3 agonists butaprost and sulprostone, was added to fresh medium, COX-2 mRNA levels remained elevated for up to 16 h. SB202190 or anti-PGE 2 monoclonal antibody compromised the stabilization of COX-2 mRNA by PGE 2 . Deletion analysis using transfected chimeric luciferase-COX-2 mRNA 3-untranslated region reporter constructs revealed that IL-1␤ increased reporter gene mRNA stability and translation via AU-containing distal regions of the untranslated region. This response was mediated entirely by a PGE 2 /p38 MAPK-dependent process. We conclude that the magnitude and duration of the induction of COX-2 mRNA, protein, and PGE 2 release by rhIL-1␤ is primarily the result of PGE 2 -dependent stabilization of COX-2 mRNA and stimulation of translation, a process involving a positive feedback loop mediated by the EP4 receptor and the downstream kinases p38 MAPK and, perhaps, cAMP-dependent protein kinase.

Cyclooxygenase 2–derived prostaglandin E2 production by corticotropin‐releasing hormone contributes to the activated cAMP response element binding protein content in rheumatoid arthritis synovial tissue

“…Kinase p38 can phosphorylate members of the CREB/ATF family, rendering them transcriptionally competent (51). It has recently been demonstrated that p38 MAP kinase and the cAMP/PKA pathway interact to transactivate the cox-2 promoter in response to IL-1␤ in human synoviocytes (32). We have confirmed that CRH signals through similar CREB/ATF factors in RA synovium and rapidly contributes to enhanced CREB-1 and ATF-2 binding activity in primary RA endothelial cells.…”

“…We have confirmed that CRH signals through similar CREB/ATF factors in RA synovium and rapidly contributes to enhanced CREB-1 and ATF-2 binding activity in primary RA endothelial cells. Thus, the findings from these experiments, taken together with those from previous studies (32,51), suggest that COX-2-dependent PGE 2 production by CRH may be due, in part, to the transcriptional activation of CREB/ATF proteins by CRH.…”

“…Phosphorylation of various members of the CREB/ATF family, including CREB-1, CREB-2, ATF-1, and ATF-2, is essential for the activation of transcription of the cox-2 gene in endothelial cells, fibroblasts, and chondrocytes (52). The magnitude and duration of the induction of COX-2 mRNA and protein and PGE 2 release by IL-1␤ are primarily the result of PGE 2 -dependent stabilization of COX-2 mRNA and stimulation of translation (32). Significantly, and in accordance with data from the studies of EP4 Ϫ/Ϫ mice, this process involves a positive mechanism mediated by the EP 4 receptor and downstream p38 MAPK and cAMP-dependent PKA activity (32).…”

“…The magnitude and duration of the induction of COX-2 mRNA and protein and PGE 2 release by IL-1␤ are primarily the result of PGE 2 -dependent stabilization of COX-2 mRNA and stimulation of translation (32). Significantly, and in accordance with data from the studies of EP4 Ϫ/Ϫ mice, this process involves a positive mechanism mediated by the EP 4 receptor and downstream p38 MAPK and cAMP-dependent PKA activity (32). The data presented in the present study confirm that inducible PGE 2 release is dependent on COX-2 activity, and that PGE 2 activity is mediated by enhanced CREB/ATF activity in RA synovial tissue.…”

Superoxide as a Messenger of Endothelial Function

“…the EP 2 receptor is induced by inflammatory stimuli. Interestingly, PGE 2 leads to the stabilization of COX-2 mRNA via the EP 4 receptor (interaction with the p38 MAPK pathway) (Faour et al, 2001).…”