Biophysical Sciences Program, The University of Chicago, Chicago, IL, 60637, USA.
Medical Scientist Training Program, The University of Chicago, Chicago, IL, 60637, USA.
Sci Rep. 2020 Oct 9;10(1):16912. doi: 10.1038/s41598-020-74044-6.
Blocking the interaction between cell-surface receptors and their ligands is a proven therapeutic strategy. Adhesion G protein-coupled receptors (aGPCRs) are key cell-surface receptors that regulate numerous pathophysiological processes, and their large extracellular regions (ECRs) mediate ligand binding and function. The aGPCR GPR56/ADGRG1 regulates central nervous system myelination and melanoma progression by interacting with its ligand, tissue transglutaminase 2 (TG2), but the molecular basis for this interaction is largely undefined. Here, we show that the C-terminal portion of TG2 directly interacted with the GPR56 ECR with high-nanomolar affinity, and used site-directed mutagenesis to identify a patch of conserved residues on the pentraxin/laminin-neurexin-sex-hormone-binding-globulin-like (PLL) domain of GPR56 as the TG2 binding site. Importantly, we also show that the GPR56-TG2 interaction was blocked by previously-reported synthetic proteins, termed monobodies, that bind the GPR56 ECR in a domain- and species-specific manner. This work provides unique tools to modulate aGPCR-ligand binding and establishes a foundation for the development of aGPCR-targeted therapeutics.
阻断细胞表面受体与其配体的相互作用是一种经过验证的治疗策略。黏附 G 蛋白偶联受体（aGPCR）是调节众多病理生理过程的关键细胞表面受体，其大的细胞外区域（ECRs）介导配体结合和功能。aGPCR GPR56/ADGRG1 通过与其配体组织转谷氨酰胺酶 2（TG2）相互作用来调节中枢神经系统髓鞘形成和黑色素瘤进展，但这种相互作用的分子基础在很大程度上尚未确定。在这里，我们表明 TG2 的 C 末端部分与 GPR56 的 ECR 以高纳摩尔亲和力直接相互作用，并使用定点突变来鉴定 GPR56 的 pentraxin/laminin-neurexin-sex-hormone-binding-globulin-like（PLL）结构域上的保守残基斑作为 TG2 结合位点。重要的是，我们还表明，GPR56-TG2 相互作用被先前报道的以结构域和物种特异性方式结合 GPR56 ECR 的合成蛋白，即单域抗体，所阻断。这项工作提供了调节 aGPCR-配体结合的独特工具，并为开发 aGPCR 靶向治疗奠定了基础。
