Activation of GPR18 by cannabinoid compounds: a tale of biased agonism
Activation of GPR18 by cannabinoid compounds: a tale of biased agonism
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DOI：
10.1111/bph.12746
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发表时间：
2014-08-01
影响因子：
7.3
通讯作者：
Abood, Mary E.
中科院分区：
文献类型：
--
作者：
Console-Bram, Linda;Brailoiu, Eugen;Abood, Mary E.
背景与目的gpr18是一种候选大麻素受体，但其分类存在争议。本文提出的研究的基本原理是考虑n -花生四烯醇甘氨酸（NAGly）和大麻素通过不同的g蛋白偶联途径，除了-阻滞素信号传导的影响。还检测了GPR18受体的细胞定位。实验方法在稳定表达GPR18的细胞系（HEK293/GPR18细胞）中定量钙动员和ERK1/2磷酸化。此外，使用DiscoveRx PathHunter (R) CHO-K1 GPR18 -拘捕素细胞系，定量-拘捕素的募集。在NAGly、异常大麻二酚（AbnCBD）、O-1602、O-1918和(9)-四氢大麻酚（(9)-THC）存在的情况下，HEK293/GPR18细胞内钙和ERK1/2磷酸化呈浓度依赖性增加。在NAGly、O1918和THC存在的情况下，细胞内钙的初始升高被G(q)或G（i/o）抑制所阻断。ERK1/2磷酸化被百日咳毒素和n -花生四烯酰基丝氨酸（NARAS）抑制。PathHunter CHO-K1 GPR18细胞系中-逮捕素的募集揭示了GPR18激活的差异模式；在所有测试的配体中，只有(9)-四氢大麻酚产生浓度依赖性反应。GPR18受体在HEK293/GPR18细胞内的定位既在细胞内，也在质膜上。结论和意义这些发现表明GPR18的激活涉及几种指示偏倚激动作用的信号转导途径，从而为文献中发现的GPR18激活的明显差异提供了合理的解释。此外，本文提出的结果进一步证明了GPR18作为大麻素受体的候选。
Background and PurposeGPR18 is a candidate cannabinoid receptor, but its classification as such is controversial. The rationale of the study presented herein was to consider the effects of N-arachidonoyl glycine (NAGly) and cannabinoids via differential G-protein coupled pathways, in addition to -arrestin signalling. Cellular localization of GPR18 receptors was also examined.Experimental ApproachCalcium mobilization and ERK1/2 phosphorylation were quantified in a cell line stably expressing GPR18 (HEK293/GPR18 cells). In addition, using the DiscoveRx PathHunter (R) CHO-K1 GPR18 -arrestin cell line, recruitment of -arrestin was quantified.Key ResultsConcentration-dependent increases in intracellular calcium and ERK1/2 phosphorylation were observed in the presence of NAGly, abnormal cannabidiol (AbnCBD), O-1602, O-1918 and (9)-tetrahydrocannabinol ((9)-THC) in HEK293/GPR18 cells. The initial rise in intracellular calcium in the presence of NAGly, O1918 and THC was blocked by either G(q) or G(i/o) inhibition. The ERK1/2 phosphorylation was inhibited by Pertussis toxin and N-arachidonoyl-L-serine (NARAS). Recruitment of -arrestin in the PathHunter CHO-K1 GPR18 cell line revealed a differential pattern of GPR18 activation; of all the ligands tested, only (9)-THC produced a concentration-dependent response. The localization of GPR18 receptors within the HEK293/GPR18 cells is both intracellular, and on the plasma membrane.Conclusions and ImplicationsThese findings suggest that GPR18 activation involves several signal transduction pathways indicative of biased agonism, thereby providing a plausible explanation for the apparent discrepancies in GPR18 activation found in the literature. Additionally, the results presented herein provide further evidence for GPR18 as a candidate cannabinoid receptor.