Journal
BRITISH JOURNAL OF PHARMACOLOGY
Volume 163, Issue 4, Pages 815-825Publisher
WILEY-BLACKWELL
DOI: 10.1111/j.1476-5381.2011.01263.x
Keywords
20-hydroxyeicosatetraenoic acid; peroxisome proliferator activator receptor; vascular smooth muscle cell; cytochrome P450; cyclooxygenase
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Funding
- National Science Council of Taiwan [NSC93-2320-B-182-036]
- Chang Gung University [CMRPD32046]
- Ministry of Education of Taiwan [EMRPD170061]
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BACKGROUND AND PURPOSE 20-Hydroxyeicosatetraenoic acid (20-HETE), formed from arachidonate by cytochrome P450, regulates vascular smooth muscle cell (VSMC) function. Because 20-HETE may activate peroxisome proliferator activator receptors (PPARs) and may participate in inflammatory responses, we asked whether 20-HETE may inhibit cyclooxygenase 2 (COX-2) expression by activating PPARs in VSMC. EXPERIMENTAL APPROACH Quiescent neonatal VSMC (R22D cell line), were incubated with 20-HETE, synthetic ligands of PPARs, or inhibitors of the extracellular signal regulated kinase (ERK1/2), c-jun N-terminal kinase and the transcription factor activated protein-1 before adding ATP gamma S. mRNA and protein expression of COX-2 and the promoter luciferase activity of COX-2 and PPAR response element were determined. KEY RESULTS Pretreatment with 20-HETE (5-10 mu M) significantly inhibited ATP gamma S-induced COX-2 mRNA and protein expression in VSMC. The inhibitory effect of 20-HETE on COX-2 expression was mimicked by WY14643, a PPAR alpha ligand and inhibited by MK886, a PPAR alpha inhibitor or by transfection of shRNA for PPAR alpha. Both 20-HETE and WY14643 significantly increased the PPAR-response element luciferase activity. Furthermore, ATP gamma S-induced activation of the COX-2 promoter containing the activated protein-1 site was also inhibited by pretreatment with 20-HETE, which was reversed by MK886 or by transfection with shRNA for PPAR alpha. CONCLUSIONS AND IMPLICATIONS The PPAR alpha may mediate the inhibitory effects of 20-HETE on COX-2 expression through a negative cross-talk between PPAR alpha and the COX-2 promoter.
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