Shanghai Key Laboratory of Signaling and Disease Research, Laboratory of Receptor-based Bio-medicine, School of Life Sciences and Technology, Tongji University, Shanghai, China (C.Y., Z.Z., Q.H., R.Z., X.X.); and CAS Key Laboratory of Receptor Research, National Center for Drug Screening, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China (Z.W., X.X.).
J Pharmacol Exp Ther. 2014 Jun;349(3):437-43. doi: 10.1124/jpet.114.213082. Epub 2014 Mar 14.
G protein-coupled receptor 3 (GPR3) is an orphan G protein-coupled receptor (GPCR) predominantly expressed in mammalian brain and oocytes. GPR3 plays important roles in these two organs and is known as a Gαs-coupled receptor-activated constitutively in cells. However, the signal transduction pathway and pharmacological function of GPR3 remain unclear because of the lack of a specific ligand. By use of a human embryonic kidney 293 cell line stably expressing FLAG-GPR3-green fluorescent protein, a chemical screening for GPR3 ligands was performed using homogeneous time-resolved fluorescence cAMP assay. Diphenyleneiodonium chloride (DPI) was identified as a novel agonist of GPR3 with weak or no cross-reactivity with other GPCRs. DPI was further characterized to activate several GPR3-mediated signal transduction pathways, including Ca(2+) mobilization, cAMP accumulation, membrane recruitment of β-arrestin2, and receptor desensitization. Parallel studies revealed that the activity of DPI is much more pronounced than sphingosine 1-phosphate, a previously reported GPR3 agonist. Our study identified a novel and specific agonist of GPR3, which provides a useful tool for further study of this orphan GPCR.
G 蛋白偶联受体 3（GPR3）是一种孤儿 G 蛋白偶联受体（GPCR），主要在哺乳动物大脑和卵母细胞中表达。GPR3 在这两个器官中发挥着重要作用，被称为 Gαs 偶联受体激活的细胞内持续激活受体。然而，由于缺乏特异性配体，GPR3 的信号转导途径和药理学功能仍不清楚。通过使用稳定表达 FLAG-GPR3-绿色荧光蛋白的人胚肾 293 细胞系，使用均相时间分辨荧光 cAMP 测定法对 GPR3 配体进行了化学筛选。二苯基碘鎓（DPI）被鉴定为 GPR3 的新型激动剂，与其他 GPCR 几乎没有交叉反应。进一步对 DPI 进行了表征，以激活几种 GPR3 介导的信号转导途径，包括 Ca(2+)动员、cAMP 积累、β-arrestin2 膜募集和受体脱敏。平行研究表明，DPI 的活性比先前报道的 GPR3 激动剂鞘氨醇 1-磷酸更为显著。本研究鉴定了 GPR3 的一种新型特异性激动剂，为进一步研究这种孤儿 GPCR 提供了有用的工具。
