title: Characterization of signal bias at the GLP-1 receptor induced by backbone modification of GLP-1.
abstract: The glucagon-like peptide-1 receptor (GLP-1R) is a class B G protein-coupled receptor that is a major therapeutic target for the treatment of type 2 diabetes. Activation of this receptor promotes insulin secretion and blood glucose regulation. The GLP-1R can initiate signaling through several intracellular pathways upon activation by GLP-1. GLP-1R ligands that preferentially stimulate subsets among the natural signaling pathways ("biased agonists") could be useful as tools for elucidating the consequences of specific pathways and might engender therapeutic agents with tailored effects. Using HEK-293 cells recombinantly expressing human GLP-1R, we have previously reported that backbone modification of GLP-1, via replacement of selected α-amino acid residues with β-amino acid residues, generates GLP-1 analogues with distinctive preferences for promoting G protein activation versus β-arrestin recruitment. Here, we have explored the influence of cell background across these two parameters and expanded our analysis to include affinity and other key signaling pathways (intracellular calcium mobilization and ERK phosphorylation) using recombinant human GLP-1R expressed in a CHO cell background, which has been used extensively to demonstrate biased agonism of GLP-1R ligands. The new data indicate that α/β-peptide analogues of GLP-1 exhibit a range of distinct bias profiles relative to GLP-1 and that broad assessment of signaling endpoints is required to reveal the spectrum of behavior of modified peptides. These results support the view that backbone modification via α→β amino acid replacement can enable rapid discovery of peptide hormone analogues that display substantial signal bias at a cognate GPCR.
authors.affiliation: Department of Chemistry, University of Wisconsin, Madison, WI, United States.
authors.forename: Marlies V
authors.initials: MV
authors.lastname: Hager
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Australia.
authors.forename: Lachlan
authors.initials: L
authors.lastname: Clydesdale
authors.affiliation: Department of Chemistry, University of Wisconsin, Madison, WI, United States.
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Gellman
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Australia.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Sexton
authors.affiliation: Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences and Department of Pharmacology, Monash University, Parkville, Australia. Electronic address: denise.wootten@monash.edu.
authors.forename: Denise
authors.initials: D
authors.lastname: Wootten
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D052216:Glucagon-Like Peptide 1 / Q000235:genetics* / Q000378:metabolism*; D000067757:Glucagon-Like Peptide-1 Receptor / Q000235:genetics* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D010446:Peptide Fragments / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*
chemical_list: D000067757:Glucagon-Like Peptide-1 Receptor; D010446:Peptide Fragments; D052216:Glucagon-Like Peptide 1
keywords: Biased agonism; Cell signaling; G protein coupled receptor; Glucagon-like peptide-1 receptor; Peptides