Pharmacological readdressing and mechanistic analysis of Gq activation

• Applicant: Professorin Dr. Evi Kostenis, since 10/2016
• Subject Area: Pharmacy
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 273251628

G protein-coupled receptors (GPCRs) can undergo multiple conformational changes depending on both, the binding of an agonist to the extracellular site and the binding of an intracellular adaptor protein such as a heterotrimeric G protein. Thus, the signal flow in this system is bidirectional, i.e. binding of an intracellular adaptor protein can stabilize an active receptor conformation resulting in a higher probability for agonist binding from the extracellular side and vice versa. In addition, individual GPCRs may activate multiple different G protein classes leading to a promiscuous activation of different signaling pathways. The aim of this project is to understand and to generate selective modulation of particular signaling pathways on two different levels. First, on the receptor level: pathway selectivity has been achieved by rationally designed ortho/allosteric (dualsteric) ligands which impair the conformational flexibility of the receptor protein and thus allow only the preferential Gi pathway to be activated for the muscarinic M2 receptor. In this project we will investigate whether this dualsteric concept is applicable to the Gqlinked muscarinic M1 receptor as a paradigm for Gq-linked receptors. Second, on the G protein level: the cyclic depsipeptide FR900359 is a potent and selective inhibitor of the Gq pathway, the latter being involved in a variety of biological processes including tumor cell proliferation and cancer formation. Therefore, FR900359 is an excellent starting point for systematical chemical modification and elucidation of structure-activity-relationships. In this project, we will characterize potential new G protein inhibitors from our consortium, regarding their cell type-specificity and their molecular mechanism of action. Thus, this project, located at the interface between GPCR and G protein activation, will give new mechanistic insight into the still opaque process of G protein activation.

• DFG Programme: Research Units
• Subproject of: FOR 2372: G protein signalling cascades: with new molecular probes and modulators towards novel pharmacological concepts
• International Connection: Italy
• Major Instrumentation: Mikroplattenleser
• Instrumentation Group: 3100 Immunochemische Bestimmungsgeräte (außer Immunelektrphorese 141)
• Co-Investigator: Dr. Ramona Schrage
• Cooperation Partner: Professor Dr. Marco De Amici
• Ehemaliger Antragsteller: Professor Dr. Klaus Mohr, until 9/2016