Jiang Chunxiang, Amaradhi Radhika, Ganesh Thota, Dingledine Ray
Department of Pharmacology and Chemical Biology, School of Medicine, Emory University, Atlanta, Georgia 30322, United States.
Department of Neurology, The Second Xiangya Hospital of Central South University, Changsha, 410011 Hunan, China.
ACS Chem Neurosci. 2020 May 20;11(10):1436-1446. doi: 10.1021/acschemneuro.0c00078. Epub 2020 May 6.
All reported prostaglandin EP2 receptor antagonists have a purely orthosteric, competitive mode of action. Herein, we report the characterization of compound (pubchem CID 664888) as the first EP2 antagonist that features a reversible, agonist dependent allosteric mode of action. Compound displayed an unsurmountable inhibition of cAMP accumulation stimulated by different EP2 agonists in C6 glioma cells overexpressing human EP2 (C6G-EP2). The degree of reduction of agonist potency and efficacy depended on the agonist employed. Negative allosteric modulation was not observed in C6G cells overexpressing human EP4, IP, or DP1 receptors. Moreover, in the murine microglial cell line that stably expresses human EP2 receptors (BV2-EP2), compound reduced the EP2 agonist-induced elevation of interleukin 6 (IL-6), IL-1β, and EP2 mRNA levels and increased that of tumor necrosis factor (TNF)-α. Compound was docked into a homology model of EP2. The predicted binding site on the cytoplasmic receptor surface was similar to that of allosteric inhibitors of the β2-adrenergic, CC chemokine receptor 9 (CCR9), and CC chemokine receptor 2 (CCR2) receptors, which supports the notion of a conserved G-protein-coupled receptor (GPCR) binding pocket for allosteric inhibitors. As the first agonist dependent negative allosteric modulator of EP2 receptor, the structure of this compound may provide a basis for developing improved allosteric modulators of EP2 receptors.
所有已报道的前列腺素EP2受体拮抗剂均具有纯粹的正构、竞争性作用模式。在此，我们报道化合物（PubChem CID 664888）的特性，它是首个具有可逆的、激动剂依赖性变构作用模式的EP2拮抗剂。化合物对过表达人EP2的C6胶质瘤细胞（C6G-EP2）中不同EP2激动剂刺激的cAMP积累表现出不可克服的抑制作用。激动剂效力和效能的降低程度取决于所使用的激动剂。在过表达人EP4、IP或DP1受体的C6G细胞中未观察到负性变构调节。此外，在稳定表达人EP2受体的小鼠小胶质细胞系（BV2-EP2）中，化合物降低了EP2激动剂诱导的白细胞介素6（IL-6）、IL-1β和EP2 mRNA水平的升高，并增加了肿瘤坏死因子（TNF）-α的水平。化合物被对接至EP2的同源模型中。在细胞质受体表面预测的结合位点与β2肾上腺素能、CC趋化因子受体9（CCR9）和CC趋化因子受体2（CCR2）受体的变构抑制剂的结合位点相似，这支持了变构抑制剂存在保守的G蛋白偶联受体（GPCR）结合口袋的观点。作为首个EP2受体的激动剂依赖性负性变构调节剂，该化合物的结构可为开发改进的EP2受体变构调节剂提供基础。
