Discovery of Protease-Activated Receptor 4 (PAR4)-Tethered Ligand Antagonists Using Ultralarge Virtual Screening

• Published in: ACS pharmacology & translational science 2024-04, Vol.7 (4), p.1086-1100
• Main Authors: Smith, Shannon T., Cassada, Jackson B., Von Bredow, Lukas, Erreger, Kevin, Webb, Emma M., Trombley, Trevor A., Kalbfleisch, Jacob J., Bender, Brian J., Zagol-Ikapitte, Irene, Kramlinger, Valerie M., Bouchard, Jacob L., Mitchell, Sidnee G., Tretbar, Maik, Shoichet, Brian K., Lindsley, Craig W., Meiler, Jens, Hamm, Heidi E.
• Format: Article
• Language: English
• ISSN: 2575-9108; 2575-9108
• DOI: 10.1021/acsptsci.3c00378

Here, we demonstrate a structure-based small molecule virtual screening and lead optimization pipeline using a homology model of a difficult-to-drug G-protein-coupled receptor (GPCR) target. Protease-activated receptor 4 (PAR4) is activated by thrombin cleavage, revealing a tethered ligand that activates the receptor, making PAR4 a challenging target. A virtual screen of a make-on-demand chemical library yielded a one-hit compound. From the single-hit compound, we developed a novel series of PAR4 antagonists. Subsequent lead optimization via simultaneous virtual library searches and structure-based rational design efforts led to potent antagonists of thrombin-induced activation. Interestingly, this series of antagonists was active against PAR4 activation by the native protease thrombin cleavage but not the synthetic PAR4 agonist peptide AYPGKF.