Involvement of tyrosine kinases in the induction of cyclo-oxygenase-2 in human endothelial cells.
In addition to a constitutive cyclo-oxygenase (Cox-1), human endothelial cells also possess an inducible cyclo-oxygenase (Cox-2) which plays an important role in the regulation of the synthesis of prostacyclin (prostaglandin I2). Cox-2 is regulated and expressed in large quantities upon activation of the cells by inducers such as phorbol myristate acetate (PMA), an activator of protein kinase C (PKC), or interleukin-1 alpha. We have investigated the involvement of protein tyrosine kinases in Cox-2 expression by human endothelial cells upon activation by these inducers. PMA or interleukin-1 alpha provoke an increase in the phosphorylation of substrates of 110 and 120 kDa and additional phosphorylations for a broad band of multiple substrates in the 70 kDa range. This stimulation was accompanied by the induction of Cox-2 protein, detectable after stimulation for 1 h, which is consistent with an increase in activity reflected by prostacyclin synthesis; no variation in the expression of Cox-1 could be observed. Three distinct inhibitors of protein tyrosine kinases, genistein, herbimycin or AG-213, reduced tyrosine phosphorylation of cell substrates, consistently with their pharmacological effects. Under these conditions, there was selective reduction of Cox-2 expression without modification of Cox-1. Regulation of Cox-2 induction is also dependent on the activation of PKC since Ro 31-8220 or PKC depletion by PMA prevented its induction. Our results suggest that within the time-frame of our experiments these effects on kinases are specific for Cox-2 rather than Cox-1.
U 348 INSERM, Hôpital Lariboisière, I.F.R. Biologie de la Circulation-Lariboisière, Paris, France.
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Blanco
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Habib
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Levy-Toledano
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Maclouf
D016227:Benzoquinones; D015153:Blotting, Western; D002396:Catechols / Q000494:pharmacology; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000201:enzymology*; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019833:Genistein; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis; D007529:Isoflavones / Q000494:pharmacology; D007700:Kinetics; D047029:Lactams, Macrocyclic; D009570:Nitriles / Q000494:pharmacology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D017828:Rifabutin / Q000031:analogs & derivatives; D020032:Tyrphostins; D014471:Umbilical Veins
D016227:Benzoquinones; D002396:Catechols; D004791:Enzyme Inhibitors; D007211:Indoles; D007375:Interleukin-1; D007527:Isoenzymes; D007529:Isoflavones; D047029:Lactams, Macrocyclic; D009570:Nitriles; D011809:Quinones; D011994:Recombinant Proteins; D020032:Tyrphostins; C060152:tyrphostin 47; D017828:Rifabutin; C004742:daidzein; C020754:herbimycin; D019833:Genistein; D011451:Prostaglandin-Endoperoxide Synthases; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; C064758:Ro 31-8220