Abstract
The targeting of the Glucagon-like peptide-1 receptor (GLP-1R) for diabetes and obesity is not a novel strategy, with recent therapeutics showing efficacy in weight loss and glycaemic control. However, they are also associated with side effects, including gastrointestinal disruptions and pancreatitis. Developing agonists with different signalling profiles, or that exert some tissue selectivity can circumvent these on-target, unwanted effects. Receptor activity-modifying proteins (RAMPs) offer the potential to do both, through modulation of agonist binding and signalling, as well as surface expression. The GLP-1R was found to interact with RAMP3, with the heterodimer able to bind agonist at the cell surface. RAMP3 expression biased the receptor towards Ca2+ mobilisation, away from the canonical cAMP-driven signalling. When examining G protein coupling, the interaction with RAMP3 reduced activation of the cognate Gαs, but increased secondary couplings to Gαq and Gαi. These increased couplings led to an elevation in glucose-stimulated insulin secretion when cells overexpressing RAMP3 were stimulated with GLP-1. The effects of this interaction can then inform selection of models and peptide design when targeting this receptor for therapeutic intervention.
Significance Statement G Protein-Coupled Receptors, such as the Glucagon-Like Peptide-1 (GLP-1) Receptor are common drug targets, although not without side effects due to on-target, unwanted signalling outputs. This study identifies an interacting protein, which alters its signalling to promote insulin secretion. This may improve the therapeutic potential of GLP-1 mimetics, by enhancing effectual signalling over that associated with unwanted effects, by directly targeting this receptor complex.
Competing Interest Statement
The authors have declared no competing interest.
Footnotes
Competing Interest Statement: The authors have no competing interest to declare
There were a few figure numbers incorrect in the text. Fig 6,7,8 are now in supporting information.