p38 Mitogen-activated Protein Kinase Regulates Cyclooxygenase-2 mRNA Stability and Transcription in Lipopolysaccharide-treated Human Monocytes*
- From the Kennedy Institute of Rheumatology, 1 Aspenlea Road, Hammersmith, London W6 8LH, United Kingdom
Abstract
p38 mitogen-activated protein kinase (MAPK) is activated by inflammatory stimuli such as bacterial lipopolysaccharide (LPS), interleukin-1, and tumor necrosis factor. We have previously shown that the pyridinyl imidazole SB 203580, which inhibits it, blocks the interleukin-1 induction of cyclooxygenase-2 (COX-2) and matrix metalloproteinase 1 and 3 mRNAs in fibroblasts. Here we explore the role of p38 MAPK in the response of human monocytes to LPS. 0.1 μm SB 203580 significantly inhibited the LPS induction of COX-2 and tumor necrosis factor protein and mRNAs. The activity of MAPK-activated protein kinase-2 (a substrate of p38 MAPK) in the cells was commensurately reduced. Some isoforms of c-junN-terminal kinase (which is also activated by LPS) are sensitive to SB 203580; the inhibitor had little effect on monocyte c-junN-terminal kinases up to 2 μm. We investigated the mechanism of inhibition of COX-2 induction. Transcription (measured by a nuclear run-on assay) was 60% inhibited by SB 203580 (2 μm). Importantly, we found that p38 MAPK was essential for stabilizing COX-2 mRNA: when cells stimulated for 4 h with LPS were treated with actinomycin D, COX-2 mRNA decayed slowly. Treatment of stimulated cells with 2 μm SB 203580 caused a rapid disappearance of COX-2 mRNA, even with actinomycin D present. We conclude p38 MAPK plays a role in the transcription and stabilization of COX-2 mRNA.
Footnotes
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↵* This work was supported by the Medical Research Council and the Arthritis and Rheumatism Council.The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
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↵‡ To whom correspondence should be addressed. Tel.: 44-181-383-4444; Fax: 44-181-383-4499.
- Abbreviations:
- MAPK
-
mitogen-activated protein kinase
- COX-2
-
cyclooxygenase-2
- GAPDH
-
glyceraldehyde-3-phosphate dehydrogenase
- IL
-
interleukin
- JNK
-
c-jun N-terminal kinase
- LPS
-
lipopolysaccharide
- MAPKAPK-2
-
MAPK-activated protein kinase-2
- TNF
-
tumor necrosis factor
- kb
-
kilobase pair(s)
- DTT
-
dithiothreitol
- NF
-
nuclear factor.
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- Received July 2, 1998.
- Revision received September 14, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
