title: Internalization and desensitization of the human glucose-dependent-insulinotropic receptor is affected by N-terminal acetylation of the agonist.
abstract: How incretins regulate presence of their receptors at the cell surface and their activity is of paramount importance for the development of therapeutic strategies targeting these receptors. We have studied internalization of the human Glucose-Insulinotropic Polypeptide receptor (GIPR). GIP stimulated rapid robust internalization of the GIPR, the major part being directed to lysosomes. GIPR internalization involved mainly clathrin-coated pits, AP-2 and dynamin. However, neither GIPR C-terminal region nor β-arrestin1/2 was required. Finally, N-acetyl-GIP recognized as a dipeptidyl-IV resistant analogue, fully stimulated cAMP production with a ∼15-fold lower potency than GIP and weakly stimulated GIPR internalization and desensitization of cAMP response. Furthermore, docking N-acetyl-GIP in the binding site of modeled GIPR showed slighter interactions with residues of helices 6 and 7 of GIPR compared to GIP. Therefore, incomplete or partial activity of N-acetyl-GIP on signaling involved in GIPR desensitization and internalization contributes to the enhanced incretin activity of this peptide.
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Sadek
authors.initials: S
authors.lastname: Ismail
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Dubois-Vedrenne
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Laval
authors.affiliation: Molecular Therapeutics, School of Pharmacy, Queen's University of Belfast, North Ireland, UK.
authors.forename: Irina G
authors.initials: IG
authors.lastname: Tikhonova
authors.affiliation: Cellular Imaging Facility Rangueil, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Romina
authors.initials: R
authors.lastname: D'Angelo
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Sanchez
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Clerc
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Marie-Julie
authors.initials: MJ
authors.lastname: Gherardi
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Véronique
authors.initials: V
authors.lastname: Gigoux
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France.
authors.forename: Remi
authors.initials: R
authors.lastname: Magnan
authors.affiliation: Université de Toulouse 3, EA 4552, Inserm U1048/I2MC, Toulouse, France. Electronic address: Daniel.Fourmy@inserm.fr.
authors.forename: Daniel
authors.initials: D
authors.lastname: Fourmy
mesh_terms: D000107:Acetylation; D001665:Binding Sites; D000242:Cyclic AMP / Q000378:metabolism; D005749:Gastric Inhibitory Polypeptide / Q000819:agonists* / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D054795:Incretins / Q000494:pharmacology*; D008247:Lysosomes / Q000378:metabolism; D008958:Models, Molecular; D062105:Molecular Docking Simulation; D017433:Protein Structure, Secondary; D011964:Receptors, Gastrointestinal Hormone / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D054795:Incretins; D011964:Receptors, Gastrointestinal Hormone; D005749:Gastric Inhibitory Polypeptide; C041086:gastric inhibitory polypeptide receptor; D000242:Cyclic AMP
keywords: BRET; Biased agonist; Desensitization; Fluorescence confocal microscopy; Glucose-dependent insulinotropic polypeptide; Internalization; Molecular modeling; cAMP signaling