Oxysterols induce the migration of B-lymphocytes and dendritic cells to interfollicular regions of lymphoid tissues through binding the EBI2 (GPR183) to stimulate effective adaptive immunity and antibody production during infection. Aberrant EBI2 signaling is implicated in inflammatory bowel disease, sclerosis, and infectious disease. Here, we report the cryo-EM structures of an EBI2-G_i signaling complex with its endogenous agonist 7α,25-OHC and that of an inactive EBI2 bound to the inverse agonist GSK682753A. These structures reveal an agonist binding site for the oxysterol and a potential ligand entrance site exposed to the lipid bilayer. Mutations within the oxysterol binding site and the Gα_i interface attenuate G protein signaling and abolish oxysterol-mediated cell migration indicating that G protein signaling directly involves in the oxysterol–EBI2 pathway. Together, these findings provide new insight into how EBI2 is activated by an oxysterol ligand and will facilitate the development of therapeutic approaches that target EBI2-linked diseases.

氧甾醇通过结合 EBI2 (GPR183) 诱导 B 淋巴细胞和树突状细胞迁移至淋巴组织的滤泡间区域，从而在感染过程中刺激有效的适应性免疫和抗体产生。异常的 EBI2 信号传导与炎症性肠病、硬化症和传染病有关。_{在这里，我们报告了 EBI2-G i}信号复合物及其内源性激动剂 7α,25-OHC 以及与反向激动剂 GSK682753A 结合的非活性 EBI2 的冷冻电镜结构。这些结构揭示了氧甾醇的激动剂结合位点和暴露于脂质双层的潜在配体入口位点。氧甾醇结合位点和 Gα _{i内的突变}界面减弱 G 蛋白信号传导并消除氧甾醇介导的细胞迁移，表明 G 蛋白信号传导直接参与氧甾醇-EBI2 途径。总之，这些发现为 EBI2 如何被氧甾醇配体激活提供了新的见解，并将促进针对 EBI2 相关疾病的治疗方法的开发。