High Throughtput Screening Using A Polyplexed Flow Cytometry Protein Interaction Assay (FCPIA) for Small Molecule Inhibitors of Regulator of G protein Signaling (RGS) Proteins

Regulator of G protein Signaling, or RGS, proteins serve an important regulatory role in signaling mediated by G protein-coupled receptors (GPCRs). They all share a common RGS domain that directly interacts with active, GTP-bound Gα subunits of heterotrimeric G proteins. RGS proteins stabilize the transition state for GTP hydrolysis on Gα and thus induce a conformational change in the Gα subunit that accelerates GTP hydrolysis, thereby effectively turning off signaling cascades mediated by GPCRs. This GTPase accelerating protein (GAP) activity is the canonical mechanism of action for RGS proteins, although many also possess additional functions and domains. RGS proteins are divided into four families, R4, R7, R12 and RZ based on sequence homology, domain structure as well as specificity towards Gα subunits. For reviews on RGS proteins and their potential as therapeutic targets, see e.g. [160, 377, 411, 415, 416, 512, 519, 312, 6].

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Screen Targeting Lung and Prostate Cancer Oncogene Identifies Novel Inhibitors of RGS17 and Problematic Chemical Substructures

SLAS DISCOVERY Advancing Life Sciences ◽

10.1177/2472555217752301 ◽

2018 ◽

Vol 23 (4) ◽

pp. 363-374 ◽

Cited By ~ 1

Author(s):

Christopher R. Bodle ◽

Josephine H. Schamp ◽

Joseph B. O’Brien ◽

Michael P. Hayes ◽

Meng Wu ◽

...

Keyword(s):

G Protein ◽

Small Molecule ◽

High Throughput Screening ◽

Biochemical Characterization ◽

Parent Compound ◽

Receptor Activation ◽

G Protein Signaling ◽

Conservation Of Resources ◽

Protein Signaling ◽

Rgs Protein

Regulator of G protein signaling (RGS) proteins temporally regulate heterotrimeric G protein signaling cascades elicited by G protein–coupled receptor activation and thus are essential for cell homeostasis. The dysregulation of RGS protein expression has been linked to several pathologies, spurring discovery efforts to identify small-molecule inhibitors of these proteins. Presented here are the results of a high-throughput screening (HTS) campaign targeting RGS17, an RGS protein reported to be inappropriately upregulated in several cancers. A screen of over 60,000 small molecules led to the identification of five hit compounds that inhibit the RGS17-Gαo protein-protein interaction. Chemical and biochemical characterization demonstrated that three of these hits inhibited the interaction through the decomposition of parent compound into reactive products under normal chemical library storage/usage conditions. Compound substructures susceptible to decomposition are reported and the decomposition process characterized, adding to the armamentarium of tools available to the screening field, allowing for the conservation of resources in follow-up efforts and more efficient identification of potentially decomposed compounds. Finally, analogues of one hit compound were tested, and the results establish the first ever structure-activity relationship (SAR) profile for a small-molecule inhibitor of RGS17.

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