Huang Shen-Ming, Cai Bo-Yang, Liu Lei, Yang Le-Jin, Li Zhi, Zhang Chao, Xiong Meng-Yao, Zhang Hang, Li Yan-Rong, Huang Zhi-Zhen, Sun Ying, Yang Bao-Xue, Sun Jin-Peng
Department of Physiology and Pathophysiology, School of Basic Medical Sciences, State Key Laboratory of Vascular Homeostasis and Remodeling, Beijing Key Laboratory of Cardiovascular Receptors Research, Peking University, Beijing, 100191, China.
State Key Laboratory of Bioactive Molecules and Druggability Assessment, Jinan University, Guangzhou, 510632, China.
Acta Pharmacol Sin. 2025 Jun 16. doi: 10.1038/s41401-025-01595-7.
Orally bioavailable inhibitors targeting the kidney urea transporter (UT) have the potential to serve as salt-sparing diuretics by employing a urea-selective diuretic mechanism of action distinct from that of diuretics targeting salt transporters. To elucidate the mechanism by which oral inhibitors interact with UTs, we solved the structure of a newly developed inhibitor, E3, with UT-A2 using cryo-electron microscopy. Through structural analysis and binding free energy calculations, we not only revealed the binding mode of E3 to UT-A2 but also clarified the structural basis by which E3 serves as a common competitive inhibitor of human, mouse and rat UT-A/UT-B. E3 exerts its inhibitory effect by competitively binding to the conserved Q-T-T-Q motif in the urea binding pockets of the transport channel. Moreover, we discovered that the BSBP region of UT can serve as a key region for enhancing the inhibitory potency of E3 with different UTs, which provides valuable structural insights for designing and modifying high-affinity UT inhibitors that act as diuretics.
靶向肾脏尿素转运蛋白（UT）的口服生物可利用抑制剂，有可能通过采用一种不同于靶向盐转运蛋白的利尿剂的尿素选择性利尿作用机制，来作为保盐利尿剂。为了阐明口服抑制剂与UT相互作用的机制，我们利用冷冻电子显微镜解析了一种新开发的抑制剂E3与UT-A2的结构。通过结构分析和结合自由能计算，我们不仅揭示了E3与UT-A2的结合模式，还阐明了E3作为人、小鼠和大鼠UT-A/UT-B的共同竞争性抑制剂的结构基础。E3通过竞争性结合转运通道尿素结合口袋中的保守Q-T-T-Q基序发挥其抑制作用。此外，我们发现UT的BSBP区域可作为增强E3对不同UT抑制效力的关键区域，这为设计和修饰作为利尿剂的高亲和力UT抑制剂提供了有价值的结构见解。
