Expression of cyclooxygenase-2 in rat vascular smooth muscle cells is unrelated to nuclear factor-kappaB activation.
The promoter region of cyclooxygenase-2 (COX-2) gene contains binding sites for a number of important transcription factors including cyclic AMP response element, nuclear factor-IL6, nuclear factor-kappaB (NF-kappaB) and TGF-beta response element. Several reports have documented that the activation of NF-kappaB triggers the expression of COX-2 gene. In the present study, NF-kappaB was activated by TNF-alpha in rat aortic smooth muscle cells as demonstrated by electrophoretic mobility shift assay. The activity of NF-kappaB induced by TNF-alpha was blocked by calpain inhibitor I, a potent NF-kappaB inhibitor. However, the activation of NF-kappaB was not related to the expression of COX-2 induced by TNF-alpha since calpain inhibitor I blocked the activation of NF-kappaB but not the expression of COX-2 mRNA or protein. Mutation of rat COX-2 NF-kappaB-like sites in the promoter region did not significantly reduce the promoter activity. These results suggest that the transcriptional regulation of COX-2 expression by NF-kappaB depends upon the types of cells studied and that activation of this transcription factor alone does not play an important role in the expression of COX-2 in rat smooth muscle cells.
Chen
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William Harvey Research Institute, St. Bartholomew's Hospital Medical College, Charterhouse Square, London, UK.
Wood
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EG
Wang
S H
SH
Warner
T D
TD
D000818:Animals; D002154:Calpain / Q000037:antagonists & inhibitors; D051546:Cyclooxygenase 2; D015971:Gene Expression Regulation, Enzymologic; D007527:Isoenzymes / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D016328:NF-kappa B / Q000502:physiology*; D011401:Promoter Regions, Genetic; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics*; D051381:Rats; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D007527:Isoenzymes; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D002154:Calpain