HDL-induced prostacyclin release in smooth muscle cells is dependent on cyclooxygenase-2 (Cox-2).
Cyclooxygenase-1 (Cox-1) and Cox-2 are key enzymes in the conversion of arachidonic acid to prostaglandins and other eicosanoids. We studied the effects of plasma HDL and LDL on the synthesis of prostacyclin, Cox-1/Cox-2 mRNA, and protein expression by rabbit aortic smooth muscle cells. Prostacyclin synthesis was measured by enzyme immunoassay (EIA) of the stable metabolite of prostacyclin (PGI2), 6-ketoprostaglandin F1 alpha. HDL (150 micrograms/mL) induced release of PGI2 to values 3.46 +/- 0.3-fold above control. Incubations with LDL did not induce release of PGI2. N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide (NS-398), a selective irreversible Cox-2 inhibitor, blocked the HDL-induced PGI2 synthesis. Cycloheximide, actinomycin D, and dexamethasone downregulated HDL-induced PGI2 synthesis; therefore, HDL induced de novo synthesis of protein and Cox-2 mRNA. In addition, Northern blot analyses did not reveal differences in Cox-1 mRNA levels between control and HDL-treated cells, whereas Cox-2 mRNA levels were significantly increased in treated cells. Western blot analysis also showed an increase in the levels of Cox-2 protein. Therefore, the effects of HDL on PGI2 synthesis are mediated via upregulation of Cox-2 expression.
Viñals
M
M
Cardiovascular Research Centre, CSIC-H. Saint Pau-UAB, Barcelona, Spain.
Martínez-González
J
J
Badimon
J J
JJ
Badimon
L
L
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000378:metabolism*; D015870:Gene Expression; D007527:Isoenzymes / Q000235:genetics / Q000502:physiology*; D008075:Lipoproteins, HDL / Q000502:physiology*; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000201:enzymology*; D009578:Nitrobenzenes / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000502:physiology*; D014176:Protein Biosynthesis; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000235:genetics; D011817:Rabbits; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013449:Sulfonamides / Q000494:pharmacology; D014158:Transcription, Genetic; D015854:Up-Regulation
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008075:Lipoproteins, HDL; D009578:Nitrobenzenes; D012333:RNA, Messenger; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D003907:Dexamethasone; D011464:Epoprostenol; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D011493:Protein Kinase C