Profiling cellular signaling of G-protein coupled receptors

G-protein coupled receptors (GPCRs) are implicated in the physiological regulation of nearly all biological processes and represent an important class of drug targets. Aminergic GPCRs are successfully targeted by antagonists used to treat psychiatric diseases which underline their importance as drug targets. GPCRs have been described to mediate signaling exclusively through G-protein activation. However, recent data show numerous other GPCR-interacting proteins, including ß-arrestins and different types of kinases, which mediate cellular downstream events initiating so-called G-protein-independent pathways. The interplay of G-protein dependent and independent signaling pathways results in a complex regulatory network that strongly depends on a given ligand/receptor pair and the particular cellular context. A detailed knowledge of this complex network of GPCR signaling is essential to better understand the physiological effects and side-effects of GPCR-targeting drugs as well as the mode of action of endogenous ligands. The aim of this project is to determine ligand- and context-dependent cellular response profiles in living cells and to monitor selected events of GPCR activation and downstream signaling in vivo. Therefore, we will employ the split TEV system to study GPCR activation and first level mediator recruitment. In parallel, we will adapt a recently developed multiplexed reporter system, called EXTassays, to study cellular downstream signaling by GPCRs in living cells.