1. Activation of Galpha s mediates induction of tissue-type plasminogen activator gene transcription by epoxyeicosatrienoic acids.
- Author
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Node K, Ruan XL, Dai J, Yang SX, Graham L, Zeldin DC, and Liao JK
- Subjects
- Animals, Aorta, Atropine Derivatives, Cattle, Cells, Cultured, Cyclic AMP metabolism, Cytochrome P-450 CYP2J2, GTP-Binding Protein alpha Subunits, Gi-Go metabolism, Gene Expression Regulation, Enzymologic drug effects, Humans, Polymerase Chain Reaction, Proadifen pharmacology, Promoter Regions, Genetic, Saphenous Vein, Transcription, Genetic drug effects, Transfection, 8,11,14-Eicosatrienoic Acid analogs & derivatives, 8,11,14-Eicosatrienoic Acid pharmacology, Cytochrome P-450 Enzyme System metabolism, Endothelium, Vascular enzymology, GTP-Binding Protein alpha Subunits, Gs metabolism, Gene Expression Regulation, Enzymologic physiology, Oxygenases metabolism, Tissue Plasminogen Activator genetics, Transcription, Genetic physiology
- Abstract
The epoxyeicosatrienoic acids (EETs) are products of cytochrome P450 (CYP) epoxygenases that have vasodilatory and anti-inflammatory properties. Here we report that EETs have additional fibrinolytic properties. In vascular endothelial cells, physiological concentrations of EETs, particularly 11,12-EET, or overexpression of the endothelial epoxygenase, CYP2J2, increased tissue plasminogen activator (t-PA) expression by 2.5-fold without affecting plasminogen activator inhibitor-1 expression. This increase in t-PA expression correlated with a 4-fold induction in t-PA gene transcription and a 3-fold increase in t-PA fibrinolytic activity and was blocked by the CYP inhibitor, SKF525A, but not by the calcium-activated potassium channel blocker, charybdotoxin, indicating a mechanism that does not involve endothelial cell hyperpolarization. The t-PA promoter is cAMP-responsive, and induction of t-PA gene transcription by EETs correlated with increases in intracellular cAMP levels and, functionally, with cAMP-driven promoter activity. To determine whether increases in intracellular cAMP levels were due to modulation of guanine nucleotide-binding proteins, we assessed the effects of EETs on Galpha(s) and Galpha(i2). Treatment with EETs increased Galpha(s), but not Galpha(i2), GTP-binding activity by 3.5-fold. These findings indicate that EETs possess fibrinolytic properties through the induction of t-PA and suggest that endothelial CYP2J2 may play an important role in regulating vascular hemostasis.
- Published
- 2001
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