title: Downregulation of a GPCR by β-Arrestin2-Mediated Switch from an Endosomal to a TGN Recycling Pathway.
abstract: Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone involved in nutrient homeostasis. GIP receptor (GIPR) is constitutively internalized and returned to the plasma membrane, atypical behavior for a G-protein-coupled receptor (GPCR). GIP promotes GIPR downregulation from the plasma membrane by inhibiting recycling without affecting internalization. This transient desensitization is achieved by altered intracellular trafficking of activated GIPR. GIP stimulation induces a switch in GIPR recycling from a rapid endosomal to a slow trans-Golgi network (TGN) pathway. GPCR kinases and β-arrestin2 are required for this switch in recycling. A coding sequence variant of GIPR, which has been associated with metabolic alterations, has altered post-activation trafficking characterized by enhanced downregulation and prolonged desensitization. Downregulation of the variant requires β-arrestin2 targeting to the TGN but is independent of GPCR kinases. The single amino acid substitution in the variant biases the receptor to promote GIP-stimulated β-arrestin2 recruitment without receptor phosphorylation, thereby enhancing downregulation.
authors.affiliation: Department of Biochemistry, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
authors.forename: Nazish
authors.initials: N
authors.lastname: Abdullah
authors.affiliation: Department of Biochemistry, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
authors.forename: Muheeb
authors.initials: M
authors.lastname: Beg
authors.affiliation: Department of Biochemistry, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
authors.forename: David
authors.initials: D
authors.lastname: Soares
authors.affiliation: Department of Biochemistry, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA.
authors.forename: Jeremy S
authors.initials: JS
authors.lastname: Dittman
authors.affiliation: Department of Biochemistry, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA; Department of Cardiothoracic Surgery, Weill Cornell Medicine, 1300 York Avenue, New York, NY 10065, USA. Electronic address: temcgraw@med.cornell.edu.
authors.forename: Timothy E
authors.initials: TE
authors.lastname: McGraw
mesh_terms: D041721:3T3-L1 Cells; D000818:Animals; D011992:Endosomes / Q000378:metabolism; D005749:Gastric Inhibitory Polypeptide / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D054795:Incretins / Q000235:genetics; D051379:Mice; D021381:Protein Transport / Q000235:genetics; D043562:Receptors, G-Protein-Coupled / Q000235:genetics* / Q000378:metabolism; D011964:Receptors, Gastrointestinal Hormone / Q000235:genetics* / Q000378:metabolism; D000071560:beta-Arrestin 2 / Q000235:genetics* / Q000378:metabolism; D021601:trans-Golgi Network / Q000235:genetics / Q000378:metabolism
chemical_list: D054795:Incretins; D043562:Receptors, G-Protein-Coupled; D011964:Receptors, Gastrointestinal Hormone; D000071560:beta-Arrestin 2; D005749:Gastric Inhibitory Polypeptide; C041086:gastric inhibitory polypeptide receptor
keywords: GIP; GIP receptor; GIPR downregulation; GPCR; GPCR trafficking; GRK; beta arrestin; incretin