Optimization of High Selectivity Antagonist Hits for the GPR55 Receptor

描述（由申请人提供）：GPR55是一种视紫红质样（A类）G蛋白偶联受体（GPCR），在人纹状体中高度表达（Genbank登录号#NM-005683）。 GPR55(-/-)（敲除）小鼠的特征揭示了 GPR55 受体在炎性疼痛、神经性疼痛和骨骼发育中的作用；而其他研究表明 GPR55 激活具有致癌性。 GPR55 也可能是大麻素受体，因为据报道 CB1/CB2 激动剂以及拮抗剂可作用于 GPR55。因此，GPR55 也可能在药物滥用中发挥作用。尽管有这些潜在的治疗用途，但尚未证实该受体有低纳摩尔效力配体，也没有开发出放射性配体来表征该受体的结合。缺乏此类 GPR55 配体是该领域取得进展的关键障碍。在我们的各个实验室与分子库探针生产中心网络 (MLPCN) 的 Sanford-Burnham 筛选中心之间的合作项目中，我们鉴定了一系列 GPR55 拮抗剂，这些拮抗剂属于新型、未报告的 GPR55 拮抗剂化学型，IC50 在 0.34 至 2.72 µM 范围内。还筛选了在此效力范围内的化合物的针对 GPR55 的激动剂活性以及针对 GPR35、CB1 和 CB2 的激动剂/拮抗剂活性。重要的是，许多 GPR55 拮抗剂是完全选择性的，在浓度高达 20 µM 的相关 GPCR 测定中没有观察到活性。我们在此建议利用最先进的基于结构的设计和化学信息学工具结合合成策略来利用这些有希望的高内涵筛选结果，为选定的支架开发SAR，从而识别具有高受体选择性的低纳摩尔IC50 GPR55拮抗剂。 公共卫生相关性：叙述摘要 GPR55 受体是治疗炎性疼痛、神经性疼痛和骨发育障碍的重要新治疗靶点。然而，缺乏该受体的低纳摩尔效力配体是该领域进展的关键障碍。 R21提案的目标是利用我们最近有前景的GPR55拮抗剂高通量、高内涵筛选结果，使用基于结构的设计和化学信息学工具为选定的支架开发SAR，从而鉴定出保留高受体选择性的低纳摩尔IC50 GPR55拮抗剂。

DESCRIPTION (provided by applicant): GPR55 is a rhodopsin-like (Class A) G protein-coupled receptor (GPCR), highly expressed in human striatum (Genbank accession # NM-005683). Characterizations of GPR55(-/-) (knock-out) mice reveal a role for the GPR55 receptor in inflammatory pain, neuropathic pain, and bone development; while other studies indicate that GPR55 activation is pro-carcinogenic. GPR55 may also be a cannabinoid receptor, since CB1/CB2 agonists, as well as antagonists have been reported to act at GPR55. Thus, GPR55 may also have a role to play in drug abuse. Despite these potential therapeutic uses, no low nanomolar potency ligands have been confirmed for this receptor, nor is there a radioligand developed to characterize binding at this receptor. The lack of such GPR55 ligands is a critical barrier to progress in this field. During a collaborative project between our individual laboratoris and the Sanford-Burnham screening center of the Molecular Libraries Probe Production Centers Network (MLPCN), we identified a series of GPR55 antagonists that belong to novel, unreported GPR55 antagonist chemotypes with IC50s in the 0.34 to 2.72 ¿M range. The compounds that were in this potency range were also screened for agonist activity against GPR55 along with agonist/antagonist activity against GPR35, CB1, and CB2. Importantly, many of the GPR55 antagonists were completely selective, with no observed activity in the assays for related GPCRs for concentrations up to 20 ¿M. We propose here to leverage these promising high-content screen results using state-of-the-art structure- based design and cheminformatics tools combined with a synthesis strategy to develop an SAR for selected scaffolds that leads to the identification of low nanomolar IC50 GPR55 antagonists with high receptor selectivity. PUBLIC HEALTH RELEVANCE: NARRATIVE ABSTRACT The GPR55 receptor is an important new therapeutic target for the treatment of inflammatory pain, neuropathic pain, and bone development disorders. However, the lack of low nanomolar potency ligands for this receptor is a critical barrier to progress in this field. The goal of this R21 proposal is to leverge our recent promising high- throughput, high-content screen results for antagonists of GPR55 using structure-based design and cheminformatics tools to develop an SAR for selected scaffolds that leads to the identification of low nanomolar IC50 GPR55 antagonists that retain high receptor selectivity.