|Title||Internalized Receptor for Glucose-dependent Insulinotropic Peptide stimulates adenylyl cyclase on early endosomes.|
|Publication Type||Journal Article|
|Year of Publication||2016|
|Authors||Ismail, S., M-J. Gherardi, A. Froese, M. Zanoun, V. Gigoux, P. Clerc, F. Gaits-Iacovoni, J. Steyaert, V. O. Nikolaev, and D. Fourmy|
|Date Published||2016 Nov 15|
|Keywords||Adenylyl Cyclases, Bioluminescence Resonance Energy Transfer Techniques, Chromogranins, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Endocytosis, Endosomes, Fluorescence Resonance Energy Transfer, Fluorescent Dyes, Gastric Inhibitory Polypeptide, Green Fluorescent Proteins, GTP-Binding Protein alpha Subunits, Gs, HEK293 Cells, Humans, Luminescent Proteins, Peptide Fragments, Protein Transport, rab GTP-Binding Proteins, Receptors, Gastrointestinal Hormone, Recombinant Fusion Proteins, Recombinant Proteins, Second Messenger Systems, Single-Domain Antibodies|
Until very recently, G-protein dependent signal of GPCRs was thought to originate exclusively from the plasma membrane and internalized GPCRs were considered silent. Here, we demonstrated that, once internalized and located in the membrane of early endosomes, glucose-dependent Insulinotropic receptor (GIPR) continues to trigger production of cAMP and PKA activation. Direct evidence is based on identification of the active form of Gαs in early endosomes containing GIPR using a genetically encoded GFP tagged nanobody, and on detection of a distinct FRET signal accounting for cAMP production at the surface of endosomes containing GIP, compared to endosomes without GIP. Furthermore, decrease of the sustained phase of cAMP production and PKA activation kinetics as well as reversibility of cAMP production and PKA activity following GIP washout in cells treated with a pharmacological inhibitor of GIPR internalization, and continuous increase of cAMP level over time in the presence of dominant-negative Rab7, which causes accumulation of early endosomes in cells, were noticed. Hence the GIPR joins the few GPCRs which signal through G-proteins both at plasma membrane and on endosomes.
|Alternate Journal||Biochem. Pharmacol.|
Internalized Receptor for Glucose-dependent Insulinotropic Peptide stimulates adenylyl cyclase on early endosomes.