Screening β-arrestin recruitment for the identification of natural ligands for orphan G-protein-coupled receptors.

Authors: Southern C, Cook JM, Neetoo-Isseljee Z, Taylor DL, Kettleborough CA, Merritt A, Bassoni DL, Raab WJ, Quinn E, Wehrman TS, Davenport AP, Brown AJ, Green A, Wigglesworth MJ and Rees S.
Publisher/Year: J Biomol Screen 18(5):599-609.
Pub Med ID/Journal ID: PMID:23396314


<p style="font: 13px/17px arial,helvetica,clean,sans-serif; margin: 0px 0px 0.5em; padding: 0px; border: 0px none currentcolor; color: rgb(0, 0, 0); text-transform: none; text-indent: 0px; letter-spacing: normal; word-spacing: 0px; vertical-align: baseline; white-space: normal; background-color: rgb(255, 255, 255); text-align: justify;"> A variety of G-protein-coupled receptor (GPCR) screening technologies have successfully partnered a number of GPCRs with their cognate ligands. GPCR-mediated &beta;-arrestin recruitment is now recognized as a distinct intracellular signaling pathway, and ligand-receptor interactions may show a bias toward &beta;-arrestin over classical GPCR signaling pathways. We hypothesized that the failure to identify native ligands for the remaining orphan GPCRs may be a consequence of biased &beta;-arrestin signaling. To investigate this, we assembled 10 500 candidate ligands and screened 82 GPCRs using PathHunter &beta;-arrestin recruitment technology. High-quality screening assays were validated by the inclusion of liganded receptors and the detection and confirmation of these established ligand-receptor pairings. We describe a candidate endogenous orphan GPCR ligand and a number of novel surrogate ligands. However, for the majority of orphan receptors studied, measurement of &beta;-arrestin recruitment did not lead to the identification of cognate ligands from our screening sets. &beta;-Arrestin recruitment represents a robust GPCR screening technology, and ligand-biased signaling is emerging as a therapeutically exploitable feature of GPCR biology. The identification of cognate ligands for the orphan GPCRs and the extent to which receptors may exist to preferentially signal through &beta;-arrestin in response to their native ligand remain to be determined.</p>