Characterization of 14,15-Epoxyeicosatrienoyl-Sulfonamides as 14,15-Epoxyeicosatrienoic Acid Agonists: Use for Studies of Metabolism and Ligand Binding
作者:Wenqi Yang、Blythe B. Holmes、V. Raj Gopal、R. V. Krishna Kishore、Bhavani Sangras、Xiu-Yu Yi、J. R. Falck、William B. Campbell
DOI:10.1124/jpet.107.119651
日期:2007.6
Epoxyeicosatrienoic acids (EETs) are cytochrome P450 epoxygenase metabolites of arachidonic acid. EETs mediate numerous biological functions. In coronary arteries, they regulate vascular tone by the activation of smooth muscle large-conductance, calcium-activated potassium (BKCa) channels to cause hyperpolarization and relaxation. We developed a series of 14,15-EET agonists, 14,15-EET-phenyliodosulfonamide (14,15-EET-PISA), 14,15-EET-biotinsulfonamide (14,15-EET-BSA), and 14,15-EET-benzoyldihydrocinnamide-sulfonamide (14,15-EET-BZDC-SA) as tools to characterize 14,15-EET metabolism and binding. Agonist activities of these analogs were characterized in precontraced bovine coronary arterial rings. All three analogs induced concentration-dependent relaxation and were equipotent with 14,15-EET. Relaxations to these analogs were inhibited by the BKCa channel blocker iberiotoxin (100 nM), the 14,15-EET antagonist 14,15-epoxyeicosa-5( Z )-enoylmethylsulfonamide (10 μM), and abolished by 20 mM extracellular K+. 14,15-EET-PISA is metabolized to 14,15-dihydroxyeicosatrienoyl-PISA by soluble epoxide hydrolase in bovine coronary arteries and U937 cells but not U937 cell membrane fractions. 14,15-EET-P125ISA binding to human U937 cell membranes was time-dependent, concentration-dependent, and saturable. The specific binding reached equilibrium by 15 min at 4°C and remained unchanged up to 30 min. The estimated K d and B max were 148.3 ± 36.4 nM and 3.3 ± 0.5 pmol/mg protein, respectively. These data suggest that 14,15-EET-PISA, 14,15-EET-BSA, and 14,15-EET-BZDC-SA are full 14,15-EET agonists. 14,15-EET-P125ISA is a new radiolabeled tool to study EET metabolism and binding. Our results also provide preliminary evidence that EETs exert their biological effect through a membrane binding site/receptor.
环氧二十碳三烯酸(EETs)是细胞色素P450环氧化酶代谢花生四烯酸的产物,EETs介导多种生物功能。在冠状动脉中,它们通过激活平滑肌大电导钙激活钾(BKCa)通道来调节血管紧张度,从而引起超极化和放松。我们开发了一系列14,15-EET激动剂,包括14,15-EET-苯碘磺酰胺(14,15-EET-PISA)、14,15-EET-生物素磺酰胺(14,15-EET-BSA)和14,15-EET-苯甲酰氢化肉桂酸酰胺(14,15-EET-BZDC-SA),作为表征14,15-EET代谢和结合的工具。这些类似物的激动剂活性在预收缩的牛冠状动脉环中进行了表征。所有三种类似物均诱导浓度依赖的放松,与14,15-EET相当。对这些类似物的放松反应受到BKCa通道阻滞剂伊贝利毒素(100 nM)、14,15-EET拮抗剂14,15-环氧二十碳三烯酸-5(Z)-烯酰甲磺酰胺(10 μM)的抑制,并在20 mM的细胞外K+下消失。14,15-EET-PISA在牛冠状动脉和U937细胞中被溶酶体环氧水解酶代谢为14,15-二羟基二十碳三烯酰-PISA,但在U937细胞膜分离物中不发生。14,15-EET-P125ISA与人类U937细胞膜的结合是时间依赖、浓度依赖并且具饱和性。特异性结合在4°C下15分钟达到平衡,并在30分钟内保持不变。估计的K d和B max分别为148.3 ± 36.4 nM和3.3 ± 0.5 pmol/mg蛋白。这些数据表明,14,15-EET-PISA、14,15-EET-BSA和14,15-EET-BZDC-SA是完全的14,15-EET激动剂。14,15-EET-P125ISA是研究EET代谢和结合的新型放射性标记工具。我们的结果还提供了初步证据,表明EETs通过膜结合位点/受体发挥其生物学效应。