State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Physiology and Biophysics, School of Life Sciences, Fudan University, 200438 Shanghai, China.
Department of Pharmacology and Chemical Biology, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China.
Proc Natl Acad Sci U S A. 2018 May 8;115(19):4939-4944. doi: 10.1073/pnas.1800907115. Epub 2018 Apr 19.
Allosteric modulation provides exciting opportunities for drug discovery of enzymes, ion channels, and G protein-coupled receptors. As cation channels gated by extracellular ATP, P2X receptors have attracted wide attention as new drug targets. Although small molecules targeting P2X receptors have entered into clinical trials for rheumatoid arthritis, cough, and pain, negative allosteric modulation of these receptors remains largely unexplored. Here, combining X-ray crystallography, computational modeling, and functional studies of channel mutants, we identified a negative allosteric site on P2X3 receptors, fostered by the left flipper (LF), lower body (LB), and dorsal fin (DF) domains. Using two structurally analogous subtype-specific allosteric inhibitors of P2X3, AF-353 and AF-219, the latter being a drug candidate under phase II clinical trials for refractory chronic cough and idiopathic pulmonary fibrosis, we defined the molecular interactions between the drugs and receptors and the mechanism by which allosteric changes in the LF, DF, and LB domains modulate ATP activation of P2X3. Our detailed characterization of this druggable allosteric site should inspire new strategies to develop P2X3-specific allosteric modulators for clinical use.
变构调节为酶、离子通道和 G 蛋白偶联受体的药物发现提供了令人兴奋的机会。作为由细胞外 ATP 门控的阳离子通道，P2X 受体作为新的药物靶点引起了广泛关注。尽管针对 P2X 受体的小分子已进入类风湿关节炎、咳嗽和疼痛的临床试验，但这些受体的负变构调节在很大程度上仍未得到探索。在这里，我们结合 X 射线晶体学、计算建模和通道突变体的功能研究，确定了 P2X3 受体上的一个负变构结合位点，该位点由左翼（LF）、下半身（LB）和背鳍（DF）结构域构成。使用两种结构上类似的、针对 P2X3 的亚型特异性变构抑制剂 AF-353 和 AF-219，后者是一种处于 II 期临床试验阶段的用于难治性慢性咳嗽和特发性肺纤维化的候选药物，我们定义了药物和受体之间的分子相互作用以及 LF、DF 和 LB 结构域变构变化调节 P2X3 中 ATP 激活的机制。我们对这个可成药的变构结合位点的详细表征应该为开发用于临床的 P2X3 特异性变构调节剂提供新的策略。
