Identification of Novel Functionally Selective <i>κ</i>-Opioid Receptor Scaffolds
作者:Kate L. White、Alex P. Scopton、Marie-Laure Rives、Ruslan V. Bikbulatov、Prabhakar R. Polepally、Peter J. Brown、Terrance Kenakin、Jonathan A. Javitch、Jordan K. Zjawiony、Bryan L. Roth
DOI:10.1124/mol.113.089649
日期:2014.1
The κ -opioid receptor (KOR)-dynorphin system has been implicated in the control of affect, cognition, and motivation, and is thought to be dysregulated in mood and psychotic disorders, as well as in various phases of opioid dependence. KOR agonists exhibit analgesic effects, although the adverse effects produced by some KOR agonists, including sedation, dysphoria, and hallucinations, have limited their clinical use. Interestingly, KOR-mediated dysphoria, assessed in rodents as aversion, has recently been attributed to the activation of the p38 mitogen-activated protein kinase pathway following arrestin recruitment to the activated KOR. Therefore, KOR-selective G protein–biased agonists, which do not recruit arrestin, have been proposed to be more effective analgesics, without the adverse effects triggered by the arrestin pathway. As an initial step toward identifying novel biased KOR agonists, we applied a multifaceted screening strategy utilizing both in silico and parallel screening approaches. We identified several KOR-selective ligand scaffolds with a range of signaling bias in vitro. The arylacetamide-based scaffold includes both G protein– and β -arrestin–biased ligands, while the endogenous peptides and the diterpene scaffolds are G protein biased. Interestingly, we found scaffold screening to be more successful than library screening in identifying biased ligands. Many of the identified functionally selective ligands are potent selective KOR agonists that are reported to be active in the central nervous system. They therefore represent excellent candidates for in vivo studies aiming at determining the behavioral effects mediated by specific KOR-mediated signaling cascades.
κ-阿片受体(KOR)-去甲吗啡系统与情感、认知和动机的控制有关,被认为在情绪和精神障碍以及阿片类药物依赖的不同阶段会出现失调。KOR 激动剂具有镇痛作用,但一些 KOR 激动剂产生的不良反应,包括镇静、幻觉和幻觉,限制了它们在临床上的使用。有趣的是,在啮齿类动物中被评估为厌恶的 KOR 介导的幻觉障碍最近被归因于 p38 丝裂原活化蛋白激酶通路在 arrestin 募集到活化的 KOR 后被激活。因此,有人提出,不招募 arrestin 的 KOR 选择性 G 蛋白偏倚激动剂是更有效的镇痛剂,而不会产生 arrestin 通路引发的不良反应。作为鉴定新型偏向 KOR 激动剂的第一步,我们采用了一种多方面的筛选策略,同时利用了硅学和平行筛选方法。我们发现了几种在体外具有信号偏向性的 KOR 选择性配体支架。基于芳基乙酰胺的支架既包括偏向 G 蛋白的配体,也包括偏向 β - 逮捕素的配体,而内源性肽和二萜支架则偏向 G 蛋白。有趣的是,我们发现在识别偏向配体方面,支架筛选比文库筛选更成功。许多鉴定出的功能选择性配体都是强效的选择性 KOR 激动剂,据报道它们在中枢神经系统中具有活性。因此,它们是体内研究的绝佳候选药物,旨在确定由特定 KOR 介导的信号级联介导的行为效应。