Native LDL and oxidized LDL modulate cyclooxygenase-2 expression in HUVECs through a p38-MAPK, NF-kappaB, CRE dependent pathway and affect PGE2 synthesis.
Native low density lipoproteins (n-LDL) and oxidized low density lipoproteins (Ox-LDL) play a central role in atherogenesis and possess a wide variety of biological properties. We investigated whether n-LDL or Ox-LDL modulate cyclooxygenase-1 and -2 (Cox-1 and Cox-2) expression and prostaglandins release in human endothelial cells via an MAPK-dependent pathway. HUVECs were incubated in the presence of n-LDL or Ox-LDL (30 micro g/ml for both) for 2-15 h. Real-time PCR, western blotting and immunocytochemistry were used to investigate Cox-1 and Cox-2 expression. N-LDL and Ox-LDL induced Cox-2 expression in a time- and dose-dependent manner. The Cox-2 protein was strongly induced 2 h after exposure to n-LDL or Ox-LDL, the induction was maximal after 4 h and sustained for at least 8 h. The effect was specific for Cox-2, as Cox-1 expression was not modulated either by n-LDL or by Ox-LDL. The induction of Cox-2 expression was mainly dependent on the activation of p38 MAPK. Transient transfection analysis using a Cox-2 promoter showed that n-LDL and Ox-LDL exert their effects at the transcriptional level via NF-kappaB and CREB activation. N-LDL and Ox-LDL increased PGE2 release in a Cox-2-dependent manner while TXA2 and PGI2 release were not affected either by n-LDL or Ox-LDL. The finding that n-LDL and Ox-LDL induces Cox-2 in human endothelial cells through a p38 MAPK, NF-kappaB, CREB dependent pathway thus modulating PGE2 release, suggests a new mechanism by which these lipoproteins induce endothelial dysfunction, sustaining inflammatory processes in the arterial wall.
Department of Pharmacological Sciences, University of Milan, Italy. alberico.catapano@unimi.it
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Catapano
D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D015232:Dinoprostone / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D011464:Epoprostenol / Q000096:biosynthesis; D005419:Flavonoids / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D007118:Immunoassay; D015151:Immunoblotting; D007150:Immunohistochemistry; D007213:Indomethacin / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008565:Membrane Proteins; D016328:NF-kappa B / Q000378:metabolism*; D010084:Oxidation-Reduction; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D011725:Pyridines / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013928:Thromboxane A2 / Q000096:biosynthesis; D013997:Time Factors; D014471:Umbilical Veins / Q000166:cytology; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
D052246:Cyclooxygenase 2 Inhibitors; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D016328:NF-kappa B; D011725:Pyridines; D013928:Thromboxane A2; D011464:Epoprostenol; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D007213:Indomethacin