Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.).
Drug Discovery Biology (E.T.W., A.S., E.K., P.M.S., C.V., A.C.) and Medicinal Chemistry (M.J., S.N.M., B.C., P.J.S.), Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria, Australia; and Centre for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom (A.B.T.)
Mol Pharmacol. 2018 Jul;94(1):770-783. doi: 10.1124/mol.118.111633. Epub 2018 Apr 24.
Positive allosteric modulators (PAMs) that target the M muscarinic acetylcholine (ACh) receptor (M mAChR) are potential treatments for cognitive deficits in conditions such as Alzheimer disease and schizophrenia. We recently reported novel 4-phenylpyridine-2-one and 6-phenylpyrimidin-4-one M mAChR PAMs with the potential to display different modes of positive allosteric modulation and/or agonism but whose molecular mechanisms of action remain undetermined. The current study compared the pharmacology of three such novel PAMs with the prototypical first-generation PAM, benzyl quinolone carboxylic acid (BQCA), in a recombinant Chinese hamster ovary (CHO) cell line stably expressing the human M mAChR. Interactions between the orthosteric agonists and the novel PAMs or BQCA suggested their allosteric effects were solely governed by modulation of agonist affinity. The greatest degree of positive co-operativity was observed with higher efficacy agonists, whereas minimal potentiation was observed when the modulators were tested against the lower efficacy agonist, xanomeline. Each PAM was investigated for its effects on the endogenous agonist ACh on three different signaling pathways [extracellular signal-regulated kinases 1/2 phosphorylation, inositol monophosphate (IP) accumulation, and -arrestin-2 recruitment], revealing that the allosteric potentiation generally tracked with the efficiency of stimulus-response coupling, and that there was little pathway bias in the allosteric effects. Thus, despite the identification of novel allosteric scaffolds targeting the M mAChR, the molecular mechanism of action of these compounds is largely consistent with a model of allostery previously described for BQCA, suggesting that this may be a more generalized mechanism for M mAChR PAM effects than previously appreciated.
正变构调节剂（PAMs）是一种可以靶向毒蕈碱乙酰胆碱受体（mAChR）的药物，它们可能成为治疗阿尔茨海默病和精神分裂症等疾病认知障碍的新方法。我们最近报道了几种新型的 4-苯基吡啶-2-酮和 6-苯基嘧啶-4-酮 mAChR PAMs，它们具有显示不同正变构调节和/或激动作用模式的潜力，但它们的作用机制仍未确定。本研究在稳定表达人 mAChR 的重组中国仓鼠卵巢（CHO）细胞系中，比较了这三种新型 PAMs 与原型第一代 PAM 苯并喹诺酸（BQCA）的药理学特性。变构激动剂与新型 PAMs 或 BQCA 之间的相互作用表明，它们的变构作用仅受激动剂亲和力的调节。与高效能激动剂相比，观察到最大程度的正协同作用，而当调节剂与低效能激动剂 xanomeline 进行测试时，观察到最小的增效作用。每种 PAM 都在三个不同信号通路（细胞外信号调节激酶 1/2 磷酸化、肌醇单磷酸（IP）积累和-arrestin-2 募集）上被检测其对内源性激动剂 ACh 的作用，结果表明变构增强通常与刺激-反应偶联的效率相关，并且变构作用在信号通路中没有明显的偏向性。因此，尽管鉴定了针对 mAChR 的新型变构支架，但这些化合物的作用机制在很大程度上与以前描述的 BQCA 的变构模型一致，这表明这可能是 mAChR PAM 作用的一种更普遍的机制，比以前认为的更为普遍。
