title: Structural and pharmacological characterization of novel potent and selective monoclonal antibody antagonists of glucose-dependent insulinotropic polypeptide receptor.
abstract: Glucose-dependent insulinotropic polypeptide (GIP) is an endogenous hormonal factor (incretin) that, upon binding to its receptor (GIPr; a class B G-protein-coupled receptor), stimulates insulin secretion by beta cells in the pancreas. There has been a lack of potent inhibitors of the GIPr with prolonged in vivo exposure to support studies on GIP biology. Here we describe the generation of an antagonizing antibody to the GIPr, using phage and ribosome display libraries. Gipg013 is a specific competitive antagonist with equally high potencies to mouse, rat, dog, and human GIP receptors with a Ki of 7 nm for the human GIPr. Gipg013 antagonizes the GIP receptor and inhibits GIP-induced insulin secretion in vitro and in vivo. A crystal structure of Gipg013 Fab in complex with the human GIPr extracellular domain (ECD) shows that the antibody binds through a series of hydrogen bonds from the complementarity-determining regions of Gipg013 Fab to the N-terminal α-helix of GIPr ECD as well as to residues around its highly conserved glucagon receptor subfamily recognition fold. The antibody epitope overlaps with the GIP binding site on the GIPr ECD, ensuring competitive antagonism of the receptor. This well characterized antagonizing antibody to the GIPr will be useful as a tool to further understand the biological roles of GIP.
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune, Milstein Building, Granta Park, Cambridge CB21 6GH, United Kingdom.
authors.forename: Peter
authors.initials: P
authors.lastname: Ravn
authors.forename: Chaithanya
authors.initials: C
authors.lastname: Madhurantakam
authors.forename: Susan
authors.initials: S
authors.lastname: Kunze
authors.forename: Evelyn
authors.initials: E
authors.lastname: Matthews
authors.forename: Claire
authors.initials: C
authors.lastname: Priest
authors.forename: Siobhan
authors.initials: S
authors.lastname: O'Brien
authors.forename: Andie
authors.initials: A
authors.lastname: Collinson
authors.forename: Monika
authors.initials: M
authors.lastname: Papworth
authors.forename: Maria
authors.initials: M
authors.lastname: Fritsch-Fredin
authors.forename: Lutz
authors.initials: L
authors.lastname: Jermutus
authors.forename: Lambertus
authors.initials: L
authors.lastname: Benthem
authors.forename: Markus
authors.initials: M
authors.lastname: Gruetter
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Jackson
mesh_terms: D000818:Animals; D058846:Antibodies, Monoclonal, Murine-Derived / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D018360:Crystallography, X-Ray; D004285:Dogs; D000939:Epitopes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005749:Gastric Inhibitory Polypeptide; D057809:HEK293 Cells; D006801:Humans; D006860:Hydrogen Bonding; D007140:Immunoglobulin Fab Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D007328:Insulin / Q000235:genetics / Q000378:metabolism; D000078790:Insulin Secretion; D008297:Male; D051379:Mice; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D051381:Rats; D017207:Rats, Sprague-Dawley; D011964:Receptors, Gastrointestinal Hormone / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D058846:Antibodies, Monoclonal, Murine-Derived; D000939:Epitopes; D007140:Immunoglobulin Fab Fragments; D007328:Insulin; D011964:Receptors, Gastrointestinal Hormone; D005749:Gastric Inhibitory Polypeptide; C041086:gastric inhibitory polypeptide receptor
keywords: Antagonist; Antibody Engineering; Crystal Structure; Diabetes; G-Protein-coupled Receptors (GPCR); GIP Receptor (GIPr); Glucose-dependent Insulinotropic Polypeptide (GIP); Incretin; Phage Display