title: Real-time trafficking and signaling of the glucagon-like peptide-1 receptor.
abstract: The glucagon-like peptide-1 incretin receptor (GLP-1R) of family B G protein-coupled receptors (GPCRs) is a major drug target in type-2-diabetes due to its regulatory effect on post-prandial blood-glucose levels. The mechanism(s) controlling GLP-1R mediated signaling are far from fully understood. A fundamental mechanism controlling the signaling capacity of GPCRs is the post-endocytic trafficking of receptors between recycling and degradative fates. Here, we combined microscopy with novel real-time assays to monitor both receptor trafficking and signaling in living cells. We find that the human GLP-1R internalizes rapidly and with similar kinetics in response to equipotent concentrations of GLP-1 and the stable GLP-1 analogues exendin-4 and liraglutide. Receptor internalization was confirmed in mouse pancreatic islets. GLP-1R is shown to be a recycling receptor with faster recycling rates mediated by GLP-1 as compared to exendin-4 and liraglutide. Furthermore, a prolonged cycling of ligand-activated GLP-1Rs was observed and is suggested to be correlated with a prolonged cAMP signal.
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark; Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, San Francisco, USA. Electronic address: snro@novonordisk.com.
authors.forename: Sarah Noerklit
authors.initials: SN
authors.lastname: Roed
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Pernille
authors.initials: P
authors.lastname: Wismann
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Christina Rye
authors.initials: CR
authors.lastname: Underwood
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Nikolaj
authors.initials: N
authors.lastname: Kulahin
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Iversen
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Karen Arevad
authors.initials: KA
authors.lastname: Cappelen
authors.affiliation: Department of Diabetes Protein Engineering, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Lauge
authors.initials: L
authors.lastname: Schäffer
authors.affiliation: Department of Histology and Imaging, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Janne
authors.initials: J
authors.lastname: Lehtonen
authors.affiliation: Department of Histology and Imaging, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Jacob
authors.initials: J
authors.lastname: Hecksher-Soerensen
authors.affiliation: Department of Histology and Imaging, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Anna
authors.initials: A
authors.lastname: Secher
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jesper Mosolff
authors.initials: JM
authors.lastname: Mathiesen
authors.affiliation: Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Hans
authors.initials: H
authors.lastname: Bräuner-Osborne
authors.affiliation: Ernest Gallo Clinic and Research Center, Department of Neurology, University of California San Francisco, San Francisco, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Whistler
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Sanne Moeller
authors.initials: SM
authors.lastname: Knudsen
authors.affiliation: Department of Incretin & Islet Biology, Novo Nordisk A/S, Maaloev, Denmark.
authors.forename: Maria
authors.initials: M
authors.lastname: Waldhoer
mesh_terms: D000818:Animals; D000242:Cyclic AMP / Q000378:metabolism; D000077270:Exenatide; D052216:Glucagon-Like Peptide 1 / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology*; D000067757:Glucagon-Like Peptide-1 Receptor; D057809:HEK293 Cells; D006801:Humans; D054795:Incretins / Q000378:metabolism / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D000069450:Liraglutide; D051379:Mice; D008810:Mice, Inbred C57BL; D010455:Peptides / Q000378:metabolism / Q000494:pharmacology; D055550:Protein Stability; D021381:Protein Transport; D059748:Proteolysis; D018027:Receptors, Glucagon / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects*; D059008:Time-Lapse Imaging; D014688:Venoms / Q000378:metabolism / Q000494:pharmacology
chemical_list: C000593833:GLP1R protein, human; C000593834:Glp1r protein, mouse; D000067757:Glucagon-Like Peptide-1 Receptor; D054795:Incretins; D010455:Peptides; D018027:Receptors, Glucagon; D014688:Venoms; D000069450:Liraglutide; D052216:Glucagon-Like Peptide 1; D000077270:Exenatide; D000242:Cyclic AMP
keywords: Fluorescent microscopy; Glucagon-like peptide-1; Real-time TR-FRET; Seven transmembrane-spanning receptors/G protein-coupled receptors; Trafficking; cAMP signaling