Spatial encryption of G protein-coupled receptor signaling in endosomes; Mechanisms and applications.

Within any cellular signaling system membrane trafficking is a critical mechanism for cells to translate complex networks into specific downstream responses, including the signal pathways activated by the superfamily of G protein-coupled receptors (GPCRs). Classically, membrane trafficking is viewed as a mechanism to regulate ligand sensitivity of a target tissue by controlling the level of surface receptors. Recent studies, however, have not only highlighted that GPCR trafficking is a tightly regulated process critical for spatio-temporal control of signaling, but that heterotrimeric G protein signaling can also be reactivated or continue to signal from distinct endocytic compartments, and even endosomal microdomains. The significance of spatio-temporal control will be discussed, not only with respect to how these novel molecular pathways impact our basic understanding of cellular regulation, but also our view of how aberrant signaling can result in disease. Furthermore, these mechanisms offer the potential application for novel therapeutic strategies to identify GPCR compounds with high specificity in their actions.