HDL3 induces cyclooxygenase-2 expression and prostacyclin release in human endothelial cells via a p38 MAPK/CRE-dependent pathway: effects on COX-2/PGI-synthase coupling.
OBJECTIVE
In endothelial cells, cyclooxygenase-1 (COX-1) and COX-2 both contribute to prostacyclin production. Recent findings suggest that COX-2 contributes significantly to systemic prostacyclin synthesis in humans; whether COX-2 inhibition is related to an increased cardiovascular risk is undergoing debate. HDLs have been shown to increase prostacyclin synthesis, thus in the present study we investigated the molecular mechanisms involved in this effect in endothelial cells.


RESULTS
HDL3 (30 microg/mL) induced COX-2 expression in a time- and dose-dependent manner. COX-2 was found mainly in the perinuclear area where it co-localizes with PGI synthase. Transient transfection experiments showed that CRE is required for HDL-induced COX-2 transcription, and we demonstrated that p38 MAPK activation by HDL3 is involved in COX-2 mRNA transcription and stabilization. As a consequence of COX-2-induction by HDL3 prostacyclin production increased, incubation with a COX-2 selective inhibitor blocked this effect. Moreover, HDL3 increased caveolin-1 phosphorylation, thus promoting PGI-synthase shuttling from the membrane to the perinuclear area.


CONCLUSIONS
We conclude that in endothelial cells, HDL modulates COX-2/PGI-S activity via both p38 MAPK-dependent COX-2 mRNA stability and transcription and both caveolin-1-dependent PGI-synthase shuttling and COX-2 coupling. The understanding of these mechanisms may provide new insights into the antiatherogenic role of HDL.
Department of Pharmacological Sciences, University of Milan, Italy.
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Norata
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Callegari
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Inoue
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Catapano
D051242:Caveolin 1; D022461:Caveolins / Q000502:physiology; D002478:Cells, Cultured / Q000201:enzymology / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000502:physiology; D051546:Cyclooxygenase 2; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D042783:Endothelial Cells / Q000201:enzymology* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology*; D004790:Enzyme Induction; D006801:Humans; D020672:I-kappa B Proteins / Q000502:physiology; D007091:Image Processing, Computer-Assisted; D019746:Intramolecular Oxidoreductases / Q000378:metabolism; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D008075:Lipoproteins, HDL / Q000502:physiology*; D053440:Lipoproteins, HDL3; D020935:MAP Kinase Signaling System; D008565:Membrane Proteins; D000072000:NF-KappaB Inhibitor alpha; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D044062:Prostaglandins I / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000737:chemistry; D014157:Transcription Factors / Q000502:physiology; D014162:Transfection; D014471:Umbilical Veins / Q000166:cytology
C495540:CAV1 protein, human; C115163:CREB1 protein, human; D051242:Caveolin 1; D022461:Caveolins; D017362:Cyclic AMP Response Element-Binding Protein; D020672:I-kappa B Proteins; D007527:Isoenzymes; D008075:Lipoproteins, HDL; D053440:Lipoproteins, HDL3; D008565:Membrane Proteins; C000606204:NFKBIA protein, human; D044062:Prostaglandins I; D014157:Transcription Factors; D000072000:NF-KappaB Inhibitor alpha; D003577:Cytochrome P-450 Enzyme System; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D019746:Intramolecular Oxidoreductases; C022461:prostacyclin synthetase