Endocannabinoids Anandamide and 2-Arachidonoylglycerol Are Substrates for Human CYP2J2 Epoxygenase
作者:Daniel R. McDougle、Amogh Kambalyal、Daryl D. Meling、Aditi Das
DOI:10.1124/jpet.114.216598
日期:2014.12
The endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), are arachidonic acid (AA) derivatives that are known to regulate human cardiovascular functions. CYP2J2 is the primary cytochrome P450 in the human heart and is most well known for the metabolism of AA to the biologically active epoxyeicosatrienoic acids. In this study, we demonstrate that both 2-AG and AEA are substrates for metabolism by CYP2J2 epoxygenase in the model membrane bilayers of nanodiscs. Reactions of CYP2J2 with AEA formed four AEA-epoxyeicosatrienoic acids, whereas incubations with 2-AG yielded detectable levels of only two 2-AG epoxides. Notably, 2-AG was shown to undergo enzymatic oxidative cleavage to form AA through a NADPH-dependent reaction with CYP2J2 and cytochrome P450 reductase. The formation of the predominant AEA and 2-AG epoxides was confirmed using microsomes prepared from the left myocardium of porcine and bovine heart tissues. The nuances of the ligand-protein interactions were further characterized using spectral titrations, stopped-flow small-molecule ligand egress, and molecular modeling. The experimental and theoretical data were in agreement, which showed that substitution of the AA carboxylic acid with the 2-AG ester-glycerol changes the binding interaction of these lipids within the CYP2J2 active site, leading to different product distributions. In summary, we present data for the functional metabolomics of AEA and 2-AG by a membrane-bound cardiovascular epoxygenase.
内源性大麻素,阿南达胺(AEA)和2-花生四烯酸甘油酯(2-AG),是已知能调节人类心血管功能的花生四烯酸(AA)衍生物。CYP2J2是人类心脏中的主要细胞色素P450,最为人知的是将AA代谢为生物活性环氧二十烯酸。在本研究中,我们表明2-AG和AEA都是CYP2J2环氧化酶在纳米盘膜模型中代谢的底物。CYP2J2与AEA的反应形成了四种AEA-环氧二十烯酸,而与2-AG的孵育仅产生可检测到的两种2-AG环氧化物。值得注意的是,2-AG在CYP2J2和细胞色素P450还原酶的NADPH依赖反应下,显示出经历酶促氧化裂解,形成AA。通过使用从猪和牛心脏左心肌样本制备的微粒体,确认了主要AEA和2-AG环氧化物的形成。我们进一步通过光谱滴定、停止流小分子配体逸出和分子建模来表征配体-蛋白质相互作用的细微差别。实验和理论数据一致,表明用2-AG酯甘油替代AA羧酸改变了这些脂质在CYP2J2活性位点内的结合相互作用,从而导致不同的产物分布。总之,我们提供了关于膜结合的心血管环氧化酶对AEA和2-AG的功能代谢组学的数据。