Signalling by Internalised GPCRs: Molecular Mechanisms and Physiological Relevance

• Applicant: Professor Dr. Davide Calebiro
• Subject Area: Pharmacology
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 198762480

G-protein-coupled receptors (GPCRs) are generally assumed to signal via G-proteins exclusively from the cell surface. Recently, we have shown that GPCRs can continue to signal through Gs-cAMP after agonist-induced internalisation, causing persistent cAMP elevations. This phenomenon has been explored only for few GPCRs and its functional consequences are barely understood. Here we propose to further investigate the mechanisms as well as the physiological relevance of intracellular G-protein-dependent signalling in two different endocrinological contexts: TSH signalling in the thyroid gland and LH/FSH signalling in the ovary. To achieve this goal, we will employ FRET microscopy to monitor GPCR-cAMP signalling directly in living cells. Similar optical methods with high spatio-temporal resolution will be used to follow the intracellular trafficking of GPCRs, G-proteins and their effectors. In addition, we will evaluate early effects (i.e. PKA activation and nuclear signalling) and functional consequences (i.e. thyroid hormone release and cell replication) of GPCR activation. To study GPCR signalling under physiologically relevant conditions, these experiments will be largely performed in primary thyroid and ovarian cells as well as in intact ovarian follicles. Pharmacological and genetic methods capable of interfering with GPCR internalisation will be used to discriminate between the effects of intracellular and cell-surface receptors. This study will give new insights into the ongoing life of GPCRs after internalisation.

• DFG Programme: Research Grants
• International Connection: USA
• Participating Person: Professorin Dr. Laurinda Jaffe