Development of biosensors for monitoring signaling in subcellular compartments: a powerful molecular tool for drug discovery

Abstract

G protein-coupled receptors (GPCRs) constitute the largest family of signal transducer proteins in mammals and are considered a major target for drug discovery. After stimulation, GPCRs activate G proteins and then recruit β- arrestins, which more recently has been shown to lead to G protein-independent signaling that can persist even in the internalized endosomes. Recent advances in GPCR pharmacology led to the identification of ligands that preferentially activate one of these pathways that are known as “biased agonists". Moreover, although it is assumed that G protein signaling is halted upon GPCR internalization, very recent data suggest that G protein signaling may be also triggered by GPCRs localized at the endosomes and other intracellular compartments. These mechanisms may provide spatiotemporal regulation of signaling cascades with important consequences for normal and pathological responses and for the development of better drugs. In an effort to address these issues, this project aims to investigate the spafiotemporal regulation of this second round of activation and its importance for cell physiology. We also want to address if biased agonists can also influence G protein activation from intracellular compartments with possible functional relevance. For this purpose, we will construct new BRET-based biosensors cellular activation by GPCRs localized in distinct intracellular compartments. (AU)