RT Journal Article
SR Electronic
T1 Small Molecule Positive Allosteric Modulators of the β<sub>2</sub>-Adrenoceptor Isolated from DNA Encoded Libraries
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP mol.118.111948
DO 10.1124/mol.118.111948
A1 Ahn, Seungkirl
A1 Pani, Biswaranjan
A1 Kahsai, Alem W.
A1 Olsen, Eva K.
A1 Husemoen, Gitte
A1 Vestrgaard, Mikkel
A1 Jin, Lei
A1 Zhao, Shuai
A1 Wingler, Laura M.
A1 Rambarat, Paula K.
A1 Simhal, Rishabh K.
A1 Xu, Thomas T.
A1 Sun, Lillian D.
A1 Shim, Paul J.
A1 Staus, Dean P.
A1 Huang, Li-Yin
A1 Franch, Thomas
A1 Chen, Xin
A1 Lefkowitz, Robert J.
YR 2018
UL http://molpharm.aspetjournals.org/content/early/2018/05/16/mol.118.111948.abstract
AB Conventional drug discovery efforts at the β2-adrenoceptor (β2AR) have led to the development of ligands that bind almost exclusively to the receptor's hormone-binding orthosteric site. However, targeting the largely unexplored and evolutionarily unique allosteric sites has potential for developing more specific drugs with fewer side effects than orthosteric ligands. Using our recently developed approach for screening G protein-coupled receptors (GPCRs) with DNA-encoded small molecule libraries, we have discovered and characterized the first β2AR small molecule positive allosteric modulators (PAMs) - compound-6 [(R)-N-(4-amino-1-(4-(tert-butyl)phenyl)-4-oxobutan-2-yl)-5-(N-isopropyl-N-methylsulfamoyl)-2-((4-methoxyphenyl) thio)benzamide] and its analogs. We utilized purified human β2ARs, occupied by a high affinity agonist, for the affinity-based screening of over 500 million distinct library compounds, which yielded compound-6. It exhibits a low micro-molar affinity for the agonist-occupied β2AR, and displays positive cooperativity with orthosteric agonists, thereby enhancing their binding to the receptor and ability to stabilize its active state. Compound-6 is cooperative with G protein and β-arrestin1 (a.k.a. arrestin2) to stabilize high-affinity, agonist-bound active states of the β2AR, and potentiates downstream cAMP production and receptor-recruitment of β-arrestin2 (a.k.a. arrestin3). Compound-6 is specific for the β2AR compared to the closely related β1AR. Structure-activity studies of select compound-6 analogs defined the chemical groups that are critical for its biological activity. We thus introduce the first small molecule PAMs for the β2AR, which may serve as a lead molecule for the development of novel therapeutics. The approach described here establishes a broadly applicable proof-of-concept strategy for affinity-based discovery of small molecule allosteric compounds targeting unique conformational states of GPCRs.