Internalized Receptor for Glucose-dependent Insulinotropic Peptide stimulates adenylyl cyclase on early endosomes

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• 作者：Sadek Ismail^a ; Marie-Julie Gherardi^a ; Alexander Froese^b ; Madjid Zanoun^c ; Vé ; ronique Gigoux^a ; Pascal Clerc^a ; Frederique Gaits-Iacovoni^d ; Jan Steyaert^e ; ^f ; Viacheslav O. Nikolaev^b ; Daniel Fourmy^a ; ^{Daniel.Fourmy@inserm.fr" class="auth_mail" title="E-mail the corresponding author} ;
• 关键词：GIPR ; glucose-dependent Insulinotropic Peptide Receptor ; cAMP ; 3&prime ; 5&prime ; -cyclic adenosine monophosphate ; BRET ; Bioluminescence Resonance Energy Transfer ; FRET ; Fluorescence Resonance Energy Transfer
• 刊名：Biochemical Pharmacology
• 出版年：2016
• 出版时间：15 November 2016
• 年：2016
• 卷：120
• 期：Complete
• 页码：33-45
• 全文大小：2530 K

文摘

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.