Discovery of selective probes and antagonists for G-protein-coupled receptors FPR/FPRL1 and GPR30

Abstract

Recent technological advances in flow cytometry provide a versatile platform for high throughput screening of compound libraries coupled with high-content biological testing and drug discovery. The G protein-coupled receptors (GPCRs) constitute the largest class of signaling molecules in the human genome with frequent roles in disease pathogenesis, yet many examples of orphan receptors with unknown ligands remain. The complex biology and potential for drug discovery within this class provide strong incentives for chemical biology approaches seeking to develop small molecule probes to facilitate elucidation of mechanistic pathways and enable specific manipulation of the activity of individual receptors. We have initiated small molecule probe development projects targeting two distinct families of GPCRs: the formylpeptide receptors (FPR/FPRL1) and G protein-coupled estrogen receptor (GPR30). In each case the assay for compound screening involved the development of an appropriate small molecule fluorescent probe, and the flow cytometry platform provided inherently biological rich assays that enhanced the process of identification and optimization of novel antagonists. The contributions of cheminformatics analysis tools, virtual screening, and synthetic chemistry in synergy with the biomolecular screening program have yielded valuable new chemical probes with high binding affinity, selectivity for the targeted receptor, and potent antagonist activity. This review describes the discovery of novel small molecule antagonists of FPR and FPRL1, and GPR30, and the associated characterization process involving secondary assays, cell based and in vivo studies to define the selectivity and activity of the resulting chemical probes.

Fig. (1)

Structures of FPR/FPRL1 probes: cross-reactive fluorescent peptide ligand WK(FL)YMVm, FPR antagonist 3570-0208, FPRL1 antagonist BB-V-115, previously reported FPRL1 antagonist C7.

Fig. (2)

Structures of estrogen probes: 17β-estradiol E2, 17α-estradiol 17α-E2, fluorescent estrogen ligand E2-Alexa546, permeability-restricted estrogen E2-NMe₃⁺, permeable estrogen E2-NB.

Fig. (3)

Structures of the GPR30-selective probes: agonist G-1, antagonist G15, I-125 radiotracer G40.