Abstract
N-formyl peptide receptors (FPRs) are G protein-coupled receptors (GPCR) involved in host defense and sensing cellular dysfunction. Thus, FPRs represent important therapeutic targets. In the present studies, we screened 32 ligands (agonists and antagonists) of unrelated GPCR for their ability to induce intracellular Ca2+ mobilization in human neutrophils and HL-60 cells transfected with human FPR1, FPR2, or FPR3. Screening of these compounds demonstrated that antagonists of gastrin-releasing peptide/neuromedin B receptors (BB1/BB2), PD176252 and PD168368, were potent mixed FPR1/FPR2 agonists, with nanomolar EC50 values. Cholecystokinin-1 (CCK-1) receptor agonist A-71623 was also a mixed FPR1/FPR2 agonist, but with micromolar EC50 values. Screening of 56 Trp- and Phe-based PD176252/PD168368 analogs and 41 related non-peptide/non-peptoid analogs revealed 22 additional FPR agonists. Most were potent mixed FPR1/FPR2/FPR3 agonists with nanomolar EC50 for FPR2, making them among the most potent non-peptide FPR2 agonists reported to date. In addition, these agonists were also potent chemoattractants for murine and human neutrophils and activated reactive oxygen species production in human neutrophils. Molecular modeling of the selected agonists using field point methodology allowed us to modify our previously reported pharmacophore model for the FPR2 ligand binding site. This model suggests the existence of three hydrophobic/aromatic subpockets and several binding poses of FPR2 agonists in the transmembrane region of this receptor. These studies demonstrate that FPR agonists could include ligands of unrelated GPCR and that analysis of such compounds can enhance our understanding of pharmacological effects of these ligands.
- Chemotactic peptides
- Calcium (G Protein Coupled Signals)
- Structure-activity relationships and modeling
- Leukocytes/Mast cells
- Received August 18, 2010.
- Revision received October 12, 2010.
- Accepted October 13, 2010.
- The American Society for Pharmacology and Experimental Therapeutics