Quantitative cell-based high-content screening for vasopressin receptor agonists using transfluor technology.

The authors demonstrate the use of a simple, universal G-protein-coupled receptor (GPCR) assay to screen for agonists for a specific GPCR. Cells stably expressing a green fluorescent protein (GFP)-labeled beta-arrestin fusion protein and the vasopressin V2 receptor (V2R) were used in a high-content screening (HCS) assay to screen a small peptide library for V2R agonists. Cells were treated with the peptides at a final concentration of 500 nM for 30 min. Agonist stimulation causes V2R internalization into endosomes. GFP-beta-arrestin remains associated with the V2R in endosomes, resulting in a fluorescent pattern of intracellular spots. Assay plates were automatically imaged and quantitatively analyzed using an HCS imaging platform and a fast turnkey image analysis application optimized for detection of receptor activation and intracellular spots. Hits were further evaluated to determine their potency. The combination of unique biology, automated high-content analysis, and a powerful means of validating hits results in better leads.