PT  - JOURNAL ARTICLE
AU  - Roman, David L.
AU  - Talbot, Jeffery N.
AU  - Roof, Rebecca A.
AU  - Sunahara, Roger K.
AU  - Traynor, John R.
AU  - Neubig, Richard R.
TI  - Identification of Small-Molecule Inhibitors of RGS4 Using a High-Throughput Flow Cytometry Protein Interaction Assay
AID  - 10.1124/mol.106.028670
DP  - 2007 Jan 01
TA  - Molecular Pharmacology
PG  - 169--175
VI  - 71
IP  - 1
4099  - http://molpharm.aspetjournals.org/content/71/1/169.short
4100  - http://molpharm.aspetjournals.org/content/71/1/169.full
SO  - Mol Pharmacol2007 Jan 01; 71
AB  - Regulators of G-protein signaling (RGS) proteins are important components of signal transduction pathways initiated through G-protein-coupled receptors (GPCRs). RGS proteins accelerate the intrinsic GTPase activity of G-protein α-subunits (Gα) and thus shorten the time course and reduce the magnitude of G-protein α- and βγ-subunit signaling. Inhibiting RGS action has been proposed as a means to enhance the activity and specificity of GPCR agonist drugs, but pharmacological targeting of protein-protein interactions has typically been difficult. The aim of this project was to identify inhibitors of RGS4. Using a Luminex 96-well plate bead analyzer and a novel flow-cytometric protein interaction assay to assess Gα-RGS interactions in a high-throughput screen, we identified the first small-molecule inhibitor of an RGS protein. Of 3028 compounds screened, 1, methyl N-[(4-chlorophenyl)sulfonyl]-4-nitrobenzenesulfinimidoate (CCG-4986), inhibited RGS4/Gαo binding with 3 to 5 μM potency. It binds to RGS4, inhibits RGS4 stimulation of Gαo GTPase activity in vitro, and prevents RGS4 regulation of μ-opioid-inhibited adenylyl cyclase activity in permeabilized cells. Furthermore, CCG-4986 is selective for RGS4 and does not inhibit RGS8. Thus, we demonstrate the feasibility of targeting RGS/Gα protein-protein interactions with small molecules as a novel means to modulate GPCR-mediated signaling processes. The American Society for Pharmacology and Experimental Therapeutics