Department of Biotherapy, Cancer Center and Kidney Research Institute, State Key Laboratory of Biotherapy and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
Department of Ophthalmology and Research Laboratory of Macular Disease, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China.
Proc Natl Acad Sci U S A. 2023 Sep 26;120(39):e2308435120. doi: 10.1073/pnas.2308435120. Epub 2023 Sep 21.
GPR34 is a functional G-protein-coupled receptor of Lysophosphatidylserine (LysoPS), and has pathogenic roles in numerous diseases, yet remains poorly targeted. We herein report a cryo-electron microscopy (cryo-EM) structure of GPR34 bound with LysoPS (18:1) and G protein, revealing a unique ligand recognition mode with the negatively charged head group of LysoPS occupying a polar cavity formed by TM3, 6 and 7, and the hydrophobic tail of LysoPS residing in a lateral open hydrophobic groove formed by TM3-5. Virtual screening and subsequent structural optimization led to the identification of a highly potent and selective antagonist (YL-365). Design of fusion proteins allowed successful determination of the challenging cryo-EM structure of the inactive GPR34 complexed with YL-365, which revealed the competitive binding of YL-365 in a portion of the orthosteric binding pocket of GPR34 and the antagonist-binding-induced allostery in the receptor, implicating the inhibition mechanism of YL-365. Moreover, YL-365 displayed excellent activity in a neuropathic pain model without obvious toxicity. Collectively, this study offers mechanistic insights into the endogenous agonist recognition and antagonist inhibition of GPR34, and provides proof of concept that targeting GPR34 represents a promising strategy for disease treatment.
GPR34 是溶血磷脂酰丝氨酸（LysoPS）的功能性 G 蛋白偶联受体，在许多疾病中具有发病作用，但靶向治疗效果不佳。我们在此报告了 GPR34 与 LysoPS（18:1）和 G 蛋白结合的冷冻电镜（cryo-EM）结构，揭示了一种独特的配体识别模式，其中 LysoPS 的带负电荷的头基团占据由 TM3、6 和 7 形成的极性腔，而 LysoPS 的疏水尾部位于由 TM3-5 形成的侧向开放疏水性沟槽中。虚拟筛选和随后的结构优化导致鉴定出一种高活性和选择性的拮抗剂（YL-365）。融合蛋白的设计使得难以确定的非活性 GPR34 与 YL-365 复合物的冷冻电镜结构得以成功确定，这揭示了 YL-365 在 GPR34 的部分正位结合口袋中的竞争性结合，以及受体结合诱导的变构作用，提示了 YL-365 的抑制机制。此外，YL-365 在神经病理性疼痛模型中表现出优异的活性而没有明显的毒性。总之，这项研究为 GPR34 的内源性激动剂识别和拮抗剂抑制提供了机制见解，并为靶向 GPR34 代表疾病治疗的有前途的策略提供了证据。
