20-125Iodo-14,15-epoxyeicosa-5(Z)-enoic acid

A high-affinity radioligand used to characterize the epoxyeicosatrienoic acid antagonist binding site

Yuenmu Chen, John R. Falck, Venugopal R. Tuniki, William B. Campbell

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

Epoxyeicosatrienoic acids (EETs) are endothelium-derived metabolites of arachidonic acid. They relax vascular smooth muscle by membrane hyperpolarization. These actions are inhibited by the EET antagonist, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EE5ZE). We synthesized 20- 125iodo-14,15-EE5ZE (20-125I-14,15-EE5ZE), a radiolabeled EET antagonist, and characterized its binding to cell membranes. 14,15-EET (10-9-10-5M) caused a concentration-related relaxation of the preconstricted bovine coronary artery and phosphorylation of p38 in U937 cells that were inhibited by 20-125I-14,15-EE5ZE. Specific 20- 125I-14,15-EE5ZE binding to U937 cell membranes reached equilibrium within 5 min and remained unchanged for 30 min. The binding was saturable and reversible, and it exhibited KD and Bmax values of 1.11 ± 0.13 nM and 1.13 ± 0.04 pmol/mg protein, respectively. Guanosine 5′-O-(3-thio)triphosphate (10 μM) did not change the binding, indicating antagonist binding of the ligand. Various EETs and EET analogs (10-10-10-5M) competed for 20-125I-14,15-EE5ZE binding with an order of potency of 11,12-EET = 14,15-EET > 8,9-EET = 14,15-EE5ZE > 15-hydroxyeicosatetraenoic acid = 14,15-dihydroxyeicosatrienoic acid. 8,9-Dihydroxyeicosatrienoic acid and 11-hydroxyeicosatetraenoic acid did not compete for binding. The soluble and microsomal epoxide hydrolase inhibitors (1-cyclohexyl-3-dodecyl-urea, elaidamide, and 12-hydroxyl-elaidamide) and cytochrome P450 inhibitors (sulfaphenazole and proadifen) did not compete for the binding. However, two cytochrome P450 inhibitors, N-methylsulfonyl-6-(2- propargyloxyphenyl)hexanamide (MS-PPOH) and miconazole competed for binding with Ki of 1558 and 315 nM, respectively. Miconazole and MS-PPOH, but not proadifen, inhibited 14,15-EET-induced relaxations. These findings define an EET antagonist's binding site and support the presence of an EET receptor. The inhibition of binding by some cytochrome P450 inhibitors suggests an alternative mechanism of action for these drugs and could lead to new drug candidates that target the EET binding sites.

Original languageEnglish (US)
Pages (from-to)1137-1145
Number of pages9
JournalJournal of Pharmacology and Experimental Therapeutics
Volume331
Issue number3
DOIs
StatePublished - Dec 2009

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Binding Sites
Acids
Cytochrome P-450 Enzyme System
Proadifen
Miconazole
Hydroxyeicosatetraenoic Acids
U937 Cells
Sulfaphenazole
Cell Membrane
Guanosine 5'-O-(3-Thiotriphosphate)
Epoxide Hydrolases
Vascular Smooth Muscle
Arachidonic Acid
Pharmaceutical Preparations
Hydroxyl Radical
Endothelium
20-iodo-14,15-epoxyeicosa-5-enoic acid
14,15-episulfide eicosatrienoic acid
Coronary Vessels
Phosphorylation

ASJC Scopus subject areas

  • Pharmacology
  • Molecular Medicine
  • Medicine(all)

Cite this

20-125Iodo-14,15-epoxyeicosa-5(Z)-enoic acid : A high-affinity radioligand used to characterize the epoxyeicosatrienoic acid antagonist binding site. / Chen, Yuenmu; Falck, John R.; Tuniki, Venugopal R.; Campbell, William B.

In: Journal of Pharmacology and Experimental Therapeutics, Vol. 331, No. 3, 12.2009, p. 1137-1145.

Research output: Contribution to journalArticle

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title = "20-125Iodo-14,15-epoxyeicosa-5(Z)-enoic acid: A high-affinity radioligand used to characterize the epoxyeicosatrienoic acid antagonist binding site",
abstract = "Epoxyeicosatrienoic acids (EETs) are endothelium-derived metabolites of arachidonic acid. They relax vascular smooth muscle by membrane hyperpolarization. These actions are inhibited by the EET antagonist, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EE5ZE). We synthesized 20- 125iodo-14,15-EE5ZE (20-125I-14,15-EE5ZE), a radiolabeled EET antagonist, and characterized its binding to cell membranes. 14,15-EET (10-9-10-5M) caused a concentration-related relaxation of the preconstricted bovine coronary artery and phosphorylation of p38 in U937 cells that were inhibited by 20-125I-14,15-EE5ZE. Specific 20- 125I-14,15-EE5ZE binding to U937 cell membranes reached equilibrium within 5 min and remained unchanged for 30 min. The binding was saturable and reversible, and it exhibited KD and Bmax values of 1.11 ± 0.13 nM and 1.13 ± 0.04 pmol/mg protein, respectively. Guanosine 5′-O-(3-thio)triphosphate (10 μM) did not change the binding, indicating antagonist binding of the ligand. Various EETs and EET analogs (10-10-10-5M) competed for 20-125I-14,15-EE5ZE binding with an order of potency of 11,12-EET = 14,15-EET > 8,9-EET = 14,15-EE5ZE > 15-hydroxyeicosatetraenoic acid = 14,15-dihydroxyeicosatrienoic acid. 8,9-Dihydroxyeicosatrienoic acid and 11-hydroxyeicosatetraenoic acid did not compete for binding. The soluble and microsomal epoxide hydrolase inhibitors (1-cyclohexyl-3-dodecyl-urea, elaidamide, and 12-hydroxyl-elaidamide) and cytochrome P450 inhibitors (sulfaphenazole and proadifen) did not compete for the binding. However, two cytochrome P450 inhibitors, N-methylsulfonyl-6-(2- propargyloxyphenyl)hexanamide (MS-PPOH) and miconazole competed for binding with Ki of 1558 and 315 nM, respectively. Miconazole and MS-PPOH, but not proadifen, inhibited 14,15-EET-induced relaxations. These findings define an EET antagonist's binding site and support the presence of an EET receptor. The inhibition of binding by some cytochrome P450 inhibitors suggests an alternative mechanism of action for these drugs and could lead to new drug candidates that target the EET binding sites.",
author = "Yuenmu Chen and Falck, {John R.} and Tuniki, {Venugopal R.} and Campbell, {William B.}",
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T2 - A high-affinity radioligand used to characterize the epoxyeicosatrienoic acid antagonist binding site

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AU - Tuniki, Venugopal R.

AU - Campbell, William B.

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N2 - Epoxyeicosatrienoic acids (EETs) are endothelium-derived metabolites of arachidonic acid. They relax vascular smooth muscle by membrane hyperpolarization. These actions are inhibited by the EET antagonist, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EE5ZE). We synthesized 20- 125iodo-14,15-EE5ZE (20-125I-14,15-EE5ZE), a radiolabeled EET antagonist, and characterized its binding to cell membranes. 14,15-EET (10-9-10-5M) caused a concentration-related relaxation of the preconstricted bovine coronary artery and phosphorylation of p38 in U937 cells that were inhibited by 20-125I-14,15-EE5ZE. Specific 20- 125I-14,15-EE5ZE binding to U937 cell membranes reached equilibrium within 5 min and remained unchanged for 30 min. The binding was saturable and reversible, and it exhibited KD and Bmax values of 1.11 ± 0.13 nM and 1.13 ± 0.04 pmol/mg protein, respectively. Guanosine 5′-O-(3-thio)triphosphate (10 μM) did not change the binding, indicating antagonist binding of the ligand. Various EETs and EET analogs (10-10-10-5M) competed for 20-125I-14,15-EE5ZE binding with an order of potency of 11,12-EET = 14,15-EET > 8,9-EET = 14,15-EE5ZE > 15-hydroxyeicosatetraenoic acid = 14,15-dihydroxyeicosatrienoic acid. 8,9-Dihydroxyeicosatrienoic acid and 11-hydroxyeicosatetraenoic acid did not compete for binding. The soluble and microsomal epoxide hydrolase inhibitors (1-cyclohexyl-3-dodecyl-urea, elaidamide, and 12-hydroxyl-elaidamide) and cytochrome P450 inhibitors (sulfaphenazole and proadifen) did not compete for the binding. However, two cytochrome P450 inhibitors, N-methylsulfonyl-6-(2- propargyloxyphenyl)hexanamide (MS-PPOH) and miconazole competed for binding with Ki of 1558 and 315 nM, respectively. Miconazole and MS-PPOH, but not proadifen, inhibited 14,15-EET-induced relaxations. These findings define an EET antagonist's binding site and support the presence of an EET receptor. The inhibition of binding by some cytochrome P450 inhibitors suggests an alternative mechanism of action for these drugs and could lead to new drug candidates that target the EET binding sites.

AB - Epoxyeicosatrienoic acids (EETs) are endothelium-derived metabolites of arachidonic acid. They relax vascular smooth muscle by membrane hyperpolarization. These actions are inhibited by the EET antagonist, 14,15-epoxyeicosa-5(Z)-enoic acid (14,15-EE5ZE). We synthesized 20- 125iodo-14,15-EE5ZE (20-125I-14,15-EE5ZE), a radiolabeled EET antagonist, and characterized its binding to cell membranes. 14,15-EET (10-9-10-5M) caused a concentration-related relaxation of the preconstricted bovine coronary artery and phosphorylation of p38 in U937 cells that were inhibited by 20-125I-14,15-EE5ZE. Specific 20- 125I-14,15-EE5ZE binding to U937 cell membranes reached equilibrium within 5 min and remained unchanged for 30 min. The binding was saturable and reversible, and it exhibited KD and Bmax values of 1.11 ± 0.13 nM and 1.13 ± 0.04 pmol/mg protein, respectively. Guanosine 5′-O-(3-thio)triphosphate (10 μM) did not change the binding, indicating antagonist binding of the ligand. Various EETs and EET analogs (10-10-10-5M) competed for 20-125I-14,15-EE5ZE binding with an order of potency of 11,12-EET = 14,15-EET > 8,9-EET = 14,15-EE5ZE > 15-hydroxyeicosatetraenoic acid = 14,15-dihydroxyeicosatrienoic acid. 8,9-Dihydroxyeicosatrienoic acid and 11-hydroxyeicosatetraenoic acid did not compete for binding. The soluble and microsomal epoxide hydrolase inhibitors (1-cyclohexyl-3-dodecyl-urea, elaidamide, and 12-hydroxyl-elaidamide) and cytochrome P450 inhibitors (sulfaphenazole and proadifen) did not compete for the binding. However, two cytochrome P450 inhibitors, N-methylsulfonyl-6-(2- propargyloxyphenyl)hexanamide (MS-PPOH) and miconazole competed for binding with Ki of 1558 and 315 nM, respectively. Miconazole and MS-PPOH, but not proadifen, inhibited 14,15-EET-induced relaxations. These findings define an EET antagonist's binding site and support the presence of an EET receptor. The inhibition of binding by some cytochrome P450 inhibitors suggests an alternative mechanism of action for these drugs and could lead to new drug candidates that target the EET binding sites.

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