p38 MAPK and NF-κB mediate COX-2 expression in human airway myocytes

2003 ◽  
Vol 285 (5) ◽  
pp. L1087-L1098 ◽  
Author(s):  
Cherie A. Singer ◽  
Kimberly J. Baker ◽  
Alan McCaffrey ◽  
David P. AuCoin ◽  
Melissa A. Dechert ◽  
...  
Keyword(s):  
P38 Mapk ◽  
Binding Activity ◽  
Dependent Manner ◽  
Human Airway ◽  
Mitogen Activated Protein ◽  
Steady State Levels ◽  
Cox 2 ◽  
P38 Mapk Inhibitor ◽  
Factor Α ◽  
Sb 203580

We have previously demonstrated that p38 and extracellular signal-regulated protein kinase (ERK) mitogen-activated protein kinases (MAPK) are components of proinflammatory induced cytokine expression in human airway myocytes. The experiments described here further these studies by examining p38 MAPK and NF-κB regulation of cyclooxygenase-2 (COX-2) expression in response to a complex inflammatory stimulus consisting of 10 ng/ml interleukin (IL)-1β, tumor necrosis factor-α (TNF-α), and interferon (IFN)-γ. COX-2 expression was induced with this stimulus in a time-dependent manner, with maximal expression seen 12-20 h after treatment. Semiquantitative RT-PCR and immunoblotting experiments demonstrate decreased COX-2 expression following treatment with the p38 MAPK inhibitor SB-203580 (25 μM) or the proteosome inhibitor MG-132 (1 μM). SB-203580 did not affect cytokine-stimulated IκBα degradation, NF-κB nuclear binding activity, or NF-κB-dependent signaling from the COX-2 promoter, indicating that p38 MAPK and NF-κB may affect COX-2 expression via separate signaling pathways. SB-203580, but not MG-132, also increased the initial rate of COX-2 mRNA decay, indicating p38 MAPK, but not NF-κB, participates in the regulation of COX-2 mRNA stability. These findings suggest that although p38 MAPK and NF-κB signaling regulate steady-state levels of COX-2 expression, p38 MAPK additionally affects stability of COX-2 mRNA in cytokine-stimulated human airway myocytes.

scholarly journals Pharmacological Inhibition of p38 Mitogen-Activated Protein Kinases Affects KC/CXCL1-Induced Intraluminal Crawling, Transendothelial Migration, and Chemotaxis of NeutrophilsIn Vivo

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Najia Xu ◽  
Mokarram Hossain ◽  
Lixin Liu
Keyword(s):  
P38 Mapk ◽  
Neutrophil Recruitment ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Mitogen Activated Protein ◽  
Multistep Process ◽  
Inflammatory Processes ◽  
P38 Mapk Inhibitor

p38 mitogen-activated protein kinase (MAPK) signalling is critical in the pathophysiology of a variety of inflammatory processes. Leukocyte recruitment to the site of inflammation is a multistep process governed by specific signalling cascades. After adhesion in the lumen, many leukocytes crawl to optimal sites at endothelial junctions and transmigrate to extravascular tissue in a Mac-1-dependent manner. The signalling mechanisms that regulate postadhesion steps of intraluminal crawling, transmigration, and chemotaxis in tissue remain incompletely understood. The present study explored the effect of p38 MAPK inhibitor SB203580 on various parameters of neutrophil recruitment triggered by chemokine KC (CXCL1) gradient. Neutrophil-endothelial interactions in microvasculature of murine cremaster muscle were determined using intravital microscopy and time-lapsed video analysis. SB203580 (100 nM) did not change leukocyte rolling but significantly attenuated neutrophil adhesion, emigration, and transmigration and impaired the initiation of neutrophil crawling and transmigration. In response to KC chemotactic gradient, SB203580 significantly reduced the velocity of migration and chemotaxis index of neutrophils in tissue. The upregulation of Mac-1 expression in neutrophils stimulated by KC was significantly blunted by SB203580in vitro. Collectively, our findings demonstrate that pharmacological suppression of p38 MAPK significantly impairs multiple steps of neutrophil recruitmentin vivo.

Eriobotryae Folium Extract Suppresses LPS-Induced iNOS and COX-2 Expression by Inhibition of NF-κB and MAPK Activation in Murine Macrophages

2010 ◽  
Vol 38 (05) ◽  
pp. 985-994 ◽  
Author(s):  
Takuhiro Uto ◽  
Natnaprach Suangkaew ◽  
Osamu Morinaga ◽  
Hiroko Kariyazono ◽  
Shigeru Oiso ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Skin Diseases ◽  
Binding Activity ◽  
Eriobotrya Japonica ◽  
Prostaglandin E ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Cox 2

Eriobotryae folium (EF), the dried leaves of Eriobotrya japonica (Thunb.) Lindl. has been traditionally used to treat various diseases such as chronic bronchitis, cough, inflammation, skin diseases, and diabetes. In this study, we examined the effects of Eriobotryae folium extract (EFE) on lipopolysaccharide (LPS)-induced production of nitric oxide (NO) and prostaglandin E2(PGE2) in RAW264 murine macrophage cells. EFE suppressed LPS-induced NO and PGE2 production in a dose-dependent manner. Consistent with these observations, EFE reduced the LPS-induced expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at both protein and mRNA levels. Furthermore, EFE significantly inhibited LPS-induced NF-κB binding activity, which was associated with the inhibition of IκB-α degradation. EFE also attenuated LPS-induced phosphorylation of mitogen-activated protein kinases (MAPKs) including extracellular signal-regulated kinase (ERK), p38 MAPK and c-Jun N-terminal kinase (JNK). These results suggest that the anti-inflammatory properties of EF might result from inhibition of iNOS and COX-2 expression through the downregulation of NF-κB activation and MAPK phosphorylation in LPS-stimulated RAW264 cells.

Mitogen-activated protein kinases regulate COX-2 and mucosal recovery in ischemic-injured porcine ileum

2004 ◽  
Vol 286 (6) ◽  
pp. G906-G913 ◽  
Author(s):  
Donnie E. Shifflett ◽  
Samuel L. Jones ◽  
Adam J. Moeser ◽  
Anthony T. Blikslager
Keyword(s):  
P38 Mapk ◽  
Barrier Function ◽  
Mapk Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Prostaglandin E ◽  
Mapk Pathways ◽  
Mucosal Barrier Function ◽  
Mitogen Activated Protein ◽  
Cox 2 ◽  
Sb 203580

Mitogen-activated protein kinase (MAPK) pathways transduce signals from a diverse array of extracellular stimuli. The three primary MAPK-signaling pathways are the extracellular regulated kinases (ERK1/2), p38 MAPK, and c-Jun NH2-terminal kinase (JNK). Previous research in our laboratory has shown that COX-2-elaborated prostanoids participate in recovery of mucosal barrier function in ischemic-injured porcine ileum. Because COX-2 expression is regulated in part by MAPKs, we postulated that MAPK pathways would play an integral role in recovery of injured mucosa. Porcine mucosa was subjected to 45 min of ischemia, after which tissues were mounted in Ussing chambers, and transepithelial electrical resistance (TER) was monitored as an index of recovery of barrier function. Treatment of tissues with the p38 MAPK inhibitor SB-203580 (0.1 mM) or the ERK1/2 inhibitor PD-98059 (0.1 mM) abolished recovery. Western blot analysis revealed that SB-203580 inhibited upregulation of COX-2 that was observed in untreated ischemic-injured mucosa, whereas PD-98059 had no effect on COX-2 expression. Inhibition of TER recovery by SB-203580 or PD-98059 was overcome by administration of exogenous prostaglandin E2 (1 μM). The JNK inhibitor SP-600125 (0.1 mM) significantly increased TER and resulted in COX-2 upregulation. COX-2 expression appears to be positively and negatively regulated by the p38 MAPK and the JNK pathways, respectively. Alternatively, ERK1/2 appear to be involved in COX-2-independent reparative events that remain to be defined.

scholarly journals Oleifolioside A, a New Active Compound, Attenuates LPS-Stimulated iNOS and COX-2 Expression through the Downregulation of NF-κB and MAPK Activities in RAW 264.7 Macrophages

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hai Yang Yu ◽  
Kyoung-Sook Kim ◽  
Young-Choon Lee ◽  
Hyung-In Moon ◽  
Jai-Heon Lee
Keyword(s):  
Nitric Oxide ◽  
Mapk Signaling ◽  
Binding Activity ◽  
Prostaglandin E ◽  
Raw 264.7 ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Raw 264.7 Macrophages ◽  
Dendropanax Morbifera ◽  
Cox 2

Oleifolioside A, a new triterpenoid compound isolated fromDendropanax morbiferaLeveille (D. morbifera), was shown in this study to have potent inhibitory effects on lipopolysaccharide (LPS-)stimulated nitric oxide (NO) and prostaglandin E2(PGE2) production in RAW 264.7 macrophages. Consistent with these findings, oleifolioside A was further shown to suppress the expression of LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxigenase-2 (COX-2) in a dose-dependent manner at both the protein and mRNA levels and to significantly inhibit the DNA-binding activity and transcriptional activity of NF-κB in response to LPS. These results were found to be associated with the inhibition of the degradation and phosphorylation of IκB-αand subsequent translocation of the NF-κB p65 subunit to the nucleus. Inhibition of NF-κB activation by oleifolioside A was also shown to be mediated through the prevention of p38 MAPK and ERK1/2 phosphorylation. Taken together, our results suggest that oleifolioside A has the potential to be a novel anti-inflammatory agent capable of targeting both the NF-κB and MAPK signaling pathways.

scholarly journals Role of Mitogen-Activated Protein Kinases in Activation of Human Neutrophils by Antineutrophil Cytoplasmic Antibodies

2001 ◽  
Vol 12 (1) ◽  
pp. 37-46
Author(s):  
RALPH KETTRITZ ◽  
ADRIAN SCHREIBER ◽  
FRIEDRICH C. LUFT ◽  
HERMANN HALLER
Keyword(s):  
Flow Cytometry ◽  
Cell Surface ◽  
P38 Mapk ◽  
Respiratory Burst ◽  
Antineutrophil Cytoplasmic Antibodies ◽  
Human Neutrophils ◽  
Tnf Α ◽  
Mitogen Activated Protein ◽  
P38 Mapk Inhibitor ◽  
Mapk Inhibitor

Abstract. Antineutrophil cytoplasmic antibodies (ANCA) may be important in the pathophysiology of necrotizing vasculitis. ANCA activate human neutrophils primed with tumor necrosis factor-α (TNF-α) in vitro. TNF-α priming results in translocation of ANCA antigens to the cell surface, where they are recognized by the antibodies. The signaling mechanisms involved in TNF-α priming and subsequent ANCA-induced activation were investigated. TNF-α-primed neutrophils were stimulated with monoclonal antibodies (MAb) to human myeloperoxidase (MPO) and proteinase 3 (PR3), and with preparations of human ANCA (three patients with PR3-ANCA and two patients with MPO-ANCA). Respiratory burst was measured with superoxide dismutase-inhibitable ferricytochrome C reduction and using dihydro-rhodamine-1,2,3. Phosphorylation of p38 mitogen-activated protein kinase (p38-MAPK) and the extracellular signal-regulated kinase (ERK) were assessed by immunoblotting. ANCA-antigen translocation was studied by flow cytometry. The tyrosine phosphorylation inhibitor genistein, but not calphostin or staurosporin, resulted in a significant dose-dependent superoxide generation inhibition (11.6 ± 1.7 nmol to 2.1 ± 0.5 for PR3-ANCA, and 16.0 ± 2.8 to 3.3 ± 1.3 for MPO-ANCA). The p38-MAPK inhibitor (SB202190) and the ERK inhibitor (PD98059) diminished PR3-ANCA-mediated superoxide production dose dependently (11.6 ± 1.7 nmol O2- to 1.9 ± 0.6 with 50 μM SB202190 and 4.0 ± 0.6 with 50 μM PD098059, respectively). For MPO-ANCA, the results were similar (16.0 ± 2.8 nmol to 0.9 ± 1.0 nmol with SB202190 and 6.4 ± 2.4 nmol with PD98059, respectively). Western blot showed phosphorylation of both p38-MAPK and ERK during TNF-α priming. The p38-MAPK inhibitor and the ERK inhibitor showed the strongest effect on respiratory burst when added before TNF-α priming, further supporting an important role for both signaling pathways in the priming process. Flow cytometry showed that p38-MAPK inhibition decreased the translocation of PR3 (by 93 ± 2%) and of MPO (by 64 ± 2%). In contrast, no such effect was seen when ERK was inhibited. Thus, p38-MAPK and ERK are important for the TNF-α-mediated priming of neutrophils enabling subsequent ANCA-induced respiratory burst. However, both pathways show differential effects, whereby p38-MAPK controls the translocation of ANCA antigens to the cell surface.

TLR5-mediated activation of p38 MAPK regulates epithelial IL-8 expression via posttranscriptional mechanism

2003 ◽  
Vol 285 (2) ◽  
pp. G282-G290 ◽  
Author(s):  
Yimin Yu ◽  
Hui Zeng ◽  
Sean Lyons ◽  
Adam Carlson ◽  
Didier Merlin ◽  
...  
Keyword(s):  
P38 Mapk ◽  
Mrna Stability ◽  
Mrna Translation ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Maximal Inhibition ◽  
Mapk Activation ◽  
Intestinal Epithelia ◽  
Tnf Α ◽  
Sb 203580

Toll-like receptors (TLRs) activate antimicrobial gene expression in response to detection of specific bacterial products. Relatively little is known about TLR5, the only TLR thought to be preferentially expressed by epithelial cells, beyond that it confers activation of the transcription factor NF-κB in a MyD-88 dependent manner in response to flagellin. Because TLRs, in general, are also thought to signal through members of the MAPK family, we examined flagellin-induced MAPK activation (via examining its phosphorylation status) and its subsequent role in expression of the chemokine IL-8 in polarized intestinal epithelia. Flagellin, like other proinflammatory stimuli (TNF-α, Salmonella typhimurium), activated p38 MAPK in a TLR5-dependent manner, whereas aflagellate bacteria or EGF did not activate this kinase. Although ERK1 and -2 were also observed to be activated in response to flagellin, their activation was not restricted to proinflammatory stimuli because they were also potently activated by aflagellate bacteria ( S. typhimurium or Escherichia coli) and EGF (neither of which activate NF-κB in these cells). Pharmacological inhibition of p38 MAPK (by SB-203580) potently (IC50 = 10 nM) reduced expression of IL-8 protein (maximal inhibition, 75%) but had no effect on NF-κB activation, only slightly attenuated upregulation of IL-8 mRNA levels in response to flagellin, and did not effect IL-8 mRNA stability. Together, these results indicate that epithelial TLR5 mediates p38 activation and subsequently regulates flagellin-induced IL-8 expression independently of NF-κB, probably by influencing IL-8 mRNA translation.

IL-1β signaling in cat lower esophageal sphincter circular muscle

2006 ◽  
Vol 291 (4) ◽  
pp. G672-G680 ◽  
Author(s):  
Weibiao Cao ◽  
Ling Cheng ◽  
Jose Behar ◽  
Piero Biancani ◽  
Karen M. Harnett
Keyword(s):  
Lower Esophageal Sphincter ◽  
P38 Mapk ◽  
Circular Muscle ◽  
Circular Smooth Muscle ◽  
Sequential Activation ◽  
Cox 2 ◽  
Esophageal Sphincter ◽  
Sb 203580

In a cat model of acute experimental esophagitis, resting in vivo lower esophageal sphincter (LES) pressure and in vitro tone are lower than in normal LES, and the LES circular smooth muscle layer contains elevated levels of IL-1β that decrease the LES tone of normal cats. We now examined the mechanisms of IL-1β-induced reduction in LES tone. IL-1β significantly reduced acetylcholine-induced Ca2+ release in Ca2+-free medium, and this effect was partially reversed by catalase, demonstrating a role of H2O2 in these changes. IL-1β significantly increased the production of H2O2, and the increase was blocked by the p38 MAPK inhibitor SB-203580, by the cytosolic phospholipase A2 (cPLA2) inhibitor AACOCF3, and by the NADPH oxidase inhibitor apocynin, but not by the MEK1 inhibitor PD-98059. IL-1β significantly increased the phosphorylation of p38 MAPK and cPLA2. IL-1β-induced cPLA2 phosphorylation was blocked by SB-203580 but not by AACOCF3, suggesting sequential activation of p38 MAPK-phosphorylating cPLA2. The IL-1β-induced reduction in LES tone was partially reversed by AACOCF3 and by the Ca2+-insensitive PLA2 inhibitor bromoenol lactone (BEL). IL-1β significantly increased cyclooxygenase (COX)-2 and PGE2 levels. The increase in PGE2 was blocked by SB-203580, AACOCF3, BEL, and the COX-2 inhibitor NS-398 but not by PD-98059 or the COX-1 inhibitor valeryl salicylate. The data suggested that IL-1β reduces LES tone by producing H2O2, which may affect Ca2+-release mechanisms and increase the synthesis of COX-2 and PGE2. Both H2O2 and PGE2 production depend on sequential activation of p38 MAPK and cPLA2. cPLA2 activates NADPH oxidases, producing H2O2, and may produce arachidonic acid, converted to PGE2 via COX-2.

p38 mitogen-activated protein kinase inhibits calcium-dependent chloride secretion in T84 colonic epithelial cells

2003 ◽  
Vol 284 (2) ◽  
pp. C339-C348 ◽  
Author(s):  
Stephen J. Keely ◽  
Kim E. Barrett
Keyword(s):  
Protein Kinase ◽  
Epithelial Cells ◽  
Signaling Pathway ◽  
P38 Mapk ◽  
Mitogen Activated Protein Kinase ◽  
Muscarinic Agonist ◽  
Colonic Epithelial Cells ◽  
Mitogen Activated Protein ◽  
Intracellular Ca ◽  
Sb 203580

We have previously shown that Ca2+-dependent Cl−secretion across intestinal epithelial cells is limited by a signaling pathway involving transactivation of the epidermal growth factor receptor (EGFR) and activation of ERK mitogen-activated protein kinase (MAPK). Here, we have investigated a possible role for p38 MAPK in regulation of Ca2+-dependent Cl− secretion. Western blot analysis of T84 colonic epithelial cells revealed that the muscarinic agonist carbachol (CCh; 100 μM) stimulated phosphorylation and activation of p38 MAPK. The p38 inhibitor SB-203580 (10 μM) potentiated and prolonged short-circuit current ( I sc) responses to CCh across voltage-clamped T84 cells to 157.4 ± 6.9% of those in control cells ( n = 21; P < 0.001). CCh-induced p38 phosphorylation was attenuated by the EGFR inhibitor tyrphostin AG-1478 (0.1 nM–10 μM) and by the Src family kinase inhibitor PP2 (20 nM–2 μM). The effects of CCh on p38 phosphorylation were mimicked by thapsigargin (TG; 2 μM), which specifically elevates intracellular Ca2+, and were abolished by the Ca2+ chelator BAPTA-AM (20 μM), implying a role for intracellular Ca2+ in mediating p38 activation. SB-203580 (10 μM) potentiated I sc responses to TG to 172.4 ± 18.1% of those in control cells ( n= 18; P < 0.001). When cells were pretreated with SB-203580 and PD-98059 to simultaneously inhibit p38 and ERK MAPKs, respectively, I sc responses to TG and CCh were significantly greater than those observed with either inhibitor alone. We conclude that Ca2+-dependent agonists stimulate p38 MAPK in T84 cells by a mechanism involving intracellular Ca2+, Src family kinases, and the EGFR. CCh-stimulated p38 activation constitutes a similar, but distinct and complementary, antisecretory signaling pathway to that of ERK MAPK.

scholarly journals Helicobacter pylori VacA Enhances Prostaglandin E2 Production through Induction of Cyclooxygenase 2 Expression via a p38 Mitogen-Activated Protein Kinase/Activating Transcription Factor 2 Cascade in AZ-521 Cells

2007 ◽  
Vol 75 (9) ◽  
pp. 4472-4481 ◽  
Author(s):  
Junzo Hisatsune ◽  
Eiki Yamasaki ◽  
Masaaki Nakayama ◽  
Daisuke Shirasaka ◽  
Hisao Kurazono ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Transcription Factor ◽  
Protein Kinase ◽  
P38 Mapk ◽  
Cyclooxygenase 2 ◽  
Mitogen Activated Protein Kinase ◽  
Mrna Levels ◽  
Mitogen Activated Protein ◽  
Cox 2 ◽  
Activating Transcription Factor

ABSTRACT Treatment of AZ-521 cells with Helicobacter pylori VacA increased cyclooxygenase 2 (COX-2) mRNA in a time- and dose-dependent manner. A p38 mitogen-activated protein kinase (MAPK) inhibitor, SB203580, blocked elevation of COX-2 mRNA levels, whereas PD98059, which blocks the Erk1/2 cascade, partially suppressed the increase. Consistent with involvement of p38 MAPK, VacA-induced accumulation of COX-2 mRNA was reduced in AZ-521 cells overexpressing a dominant-negative p38 MAPK (DN-p38). Phosphatidylinositol-specific phospholipase C, which inhibits VacA-induced p38 MAPK activation, blocked VacA-induced COX-2 expression. In parallel with COX-2 expression, VacA increased prostaglandin E2 (PGE2) production, which was inhibited by SB203580 and NS-398, a COX-2 inhibitor. VacA-induced PGE2 production was markedly attenuated in AZ-521 cells stably expressing DN-p38. VacA increased transcription of a COX-2 promoter reporter gene and activated a COX-2 promoter containing mutated NF-κB or NF-interleukin-6 sites but not a mutated cis-acting replication element (CRE) site, suggesting direct involvement of the activating transcription factor 2 (ATF-2)/CREB-binding region in VacA-induced COX-2 promoter activation. The reduction of ATF-2 expression in AZ-521 cells transformed with ATF-2-small interfering RNA duplexes resulted in suppression of COX-2 expression. Thus, VacA enhances PGE2 production by AZ-521 cells through induction of COX-2 expression via the p38 MAPK/ATF-2 cascade, leading to activation of the CRE site in the COX-2 promoter.

scholarly journals Inhibitors of Mitogen-Activated Protein Kinases Downregulate COX-2 Expression in Human Chondrocytes

2005 ◽  
Vol 2005 (5) ◽  
pp. 249-255 ◽  
Author(s):  
Riina Nieminen ◽  
Sari Leinonen ◽  
Aleksi Lahti ◽  
Katriina Vuolteenaho ◽  
Ulla Jalonen ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Proinflammatory Cytokine ◽  
Negative Control ◽  
Human Chondrocytes ◽  
Dependent Manner ◽  
Drug Concentrations ◽  
Mitogen Activated Protein ◽  
Cox 2 ◽  
Control Compound ◽  
Dose Dependent

Inducible prostaglandin synthase (cyclooxygenase-2, COX-2) is expressed in rheumatoid and osteoarthritic cartilage and produces high amounts of proinflammatory prostanoids in the joint. In the present study we investigated the effects of the inhibitors of mitogen-activated protein kinase (MAPK) pathways Erk1/2, p38, and JNK on COX-2 expression and prostaglandin E2(PGE2) production in human chondrocytes. Proinflammatory cytokine IL-1βcaused a transient activation of Erk1/2, p38, and JNK in immortalized human T/C28a2 chondrocytes and that was followed by enhanced COX-2 expression and PGE2production. PD98059 (an inhibitor of Erk1/2 pathway) suppressed IL-1-induced COX-2 expression and PGE2production in a dose-dependent manner, and seemed to have an inhibitory effect on COX-2 activity. SB203580 (an inhibitor of p38 pathway) but not its negative control compound SB202474 inhibited COX-2 protein and mRNA expression and subsequent PGE2synthesis at micromolar drug concentrations. SP600125 (a recently developed JNK inhibitor) but not its negative control compound N1-methyl-1,9-pyrazolanthrone downregulated COX-2 expression and PGE2formation in a dose-dependent manner. SP600125 did not downregulate IL-1-induced COX-2 mRNA expression when measured 2 h after addition of IL-1βbut suppressed mRNA levels in the later time points suggesting post-transcriptional regulation. Our results suggest that activation of Erk1/2, p38, and JNK pathways belongs to the signaling cascades that mediate the upregulation of COX-2 expression and PGE2production in human chondrocytes exposed to proinflammatory cytokine IL-1β.

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