8-11-14-eicosatrienoic-acid and pirinixic-acid

Cytochrome P450 (P450) eicosanoids regulate vascular tone, renal tubular transport, cellular proliferation, and inflammation. Both the CYP4A omega-hydroxylases, which catalyze 20-hydroxyeicosatetraenoic acid (20-HETE) formation, and soluble epoxide hydrolase (sEH), which catalyzes epoxyeicosatrienoic acid (EET) degradation to the dihydroxyeicosatrienoic acids (DHETs), are induced upon activation of peroxisome proliferator-activated receptor alpha (PPARalpha) by fatty acids and fibrates. In contrast, the CYP2C epoxygenases, which are responsible for EET formation, are repressed after fibrate treatment. We show here that P450 eicosanoids can bind to and activate PPARalpha and result in the modulation of PPARalpha target gene expression. In transactivation assays, 14,15-DHET, 11,2-EET, and 20-HETE were potent activators of PPARalpha. Gel shift assays showed that EETs, DHETs, and 20-HETE induced PPARalpha-specific binding to its cognate response element. Expression of apolipoprotein A-I was decreased 70% by 20-HETE, whereas apolipoprotein A-II expression was increased up to 3-fold by 11,12-EET, 14,15-DHET, and 20-HETE. In addition, P450 eicosanoids induced CYP4A1, sEH, and CYP2C11 expression, suggesting that they can regulate their own levels. Given that P450 eicosanoids have multiple cardiovascular effects, pharmacological modulation of their formation and/or degradation may yield therapeutic benefits.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Apolipoprotein A-I; Apolipoprotein A-II; Aryl Hydrocarbon Hydroxylases; Cell Line, Tumor; Cytochrome P-450 CYP2J2; Cytochrome P-450 CYP4A; Cytochrome P-450 Enzyme System; Cytochrome P450 Family 2; Cytochrome P450 Family 4; Dose-Response Relationship, Drug; Eicosanoids; Epoxide Hydrolases; Gene Expression Regulation, Enzymologic; Hepatocytes; Humans; Hydroxyeicosatetraenoic Acids; Peroxisome Proliferators; PPAR alpha; PPAR gamma; Pyrimidines; Rats; Rats, Sprague-Dawley; Response Elements; Retinoid X Receptors; RNA, Messenger; Steroid 16-alpha-Hydroxylase; Transcriptional Activation; Transfection

Soluble epoxide hydrolase (sEH) plays a major role in regulating vascular epoxyeicosatrienoic acid metabolism and function, and substituted urea derivatives that inhibit sEH activity reduce blood pressure in hypertensive rats. We found that substituted urea derivatives containing a dodecanoic acid group, besides effectively inhibiting sEH, increased peroxisome proliferator-activated receptor (PPAR) alpha activity. In PPARalpha transfected COS-7 cells, treatment with 10 microM N-cyclohexyl-N'-dodecanoic acid urea (CUDA) or N-adamantanyl-N'-dodecanoic acid urea (AUDA) produced 6- and 3-fold increases, respectively, in PPARalpha activation. Neither CUDA nor AUDA activated PPARdelta or PPARgamma directly, indicating selectivity for PPARalpha. CUDA did not alter PPARalpha protein expression, and it competitively inhibited the binding of Wy-14643 (pirinixic acid) to the ligand binding domain of PPARalpha, suggesting that it functions as a PPARalpha ligand. CUDA and AUDA were metabolized to chain-shortened beta-oxidation products, a process that reduced their potency as sEH inhibitors and their ability to bind and activate PPARalpha. N,N'-Dicylclohexylurea and N-cyclohexyl-N'-dodecylurea, sEH inhibitors that do not contain a carboxylic acid group, did not activate PPARalpha. In HepG2 cells, CUDA increased the expression of the PPARalpha-responsive gene carnitine palmitoyltransferase 1A. We conclude that CUDA and AUDA, by virtue of their carboxylic acid substitution, activate PPARalpha in addition to potently inhibiting sEH. Further development of these compounds could lead to a class of agents with hypotensive and lipid-lowering properties that may be valuable for the prevention and treatment of cardiovascular disease.

Topics: 8,11,14-Eicosatrienoic Acid; Animals; Binding, Competitive; Biotransformation; Blotting, Western; Carnitine O-Palmitoyltransferase; Cell Movement; Chlorocebus aethiops; COS Cells; Cyclohexanes; Enzyme Inhibitors; Epoxide Hydrolases; Lauric Acids; Ligands; Mice; PPAR alpha; Pyrimidines; Reverse Transcriptase Polymerase Chain Reaction; RNA; Transfection; Urea