Spatially diffuse cAMP signalling with oppositely biased GLP-1 receptor agonists in β-cells despite differences in receptor localisation
Year: 2025
Type: article
Abstract: Internalisation of G protein-coupled receptors (GPCRs) can contribute to altered cellular responses by directing signalling from non-canonical locations, such as endosomes. If signalling processes are locally constrained, active receptors in different subcellular locations could produce different downstream effects. This phenomenon may be relevant to the optimal targeting of the glucagon-like peptide-1 receptor (GLP-1R), a type 2 diabetes and obesity target GPCR for which several ligands with varying internalisation tendency have been discovered. To investigate, we compared the signalling localisation effects of two prototypical GLP-1RAs with opposite signal bias and effects on GLP-1R trafficking: exendin-asp3 (ExD3), a full agonist that drives rapid internalisation, and exendin-phe1 (ExF1), which shows much slower internalisation. After using bioorthogonal labelling and fluorescent agonist conjugates to verify the divergent trafficking patterns of ExF1 and ExD3 in β-cell lines and primary pancreatic islets, we used live cell biosensors to monitor signalling at different subcellular locations. This revealed that cAMP/PKA/ERK signalling in β-cells is in fact distributed widely across the cell over short- (<5 min) and medium-term (up to 60 min) stimulation at pharmacological (>10 pM) concentrations, with no major differences in signal localisation that could be linked to internalised versus cell surface-bound GLP-1R. Moreover, washout experiments highlighted that, whilst fast-internalising ExD3 shows much greater accumulation and binding to GLP-1R in endosomes than slow-internalising ExF1, it is a rather inefficient driver of both cAMP production in β-cells and insulin secretion from perfused rat pancreata. These data provide a greater understanding of the cellular effects of biased GLP-1R agonism.
Source: Molecular Metabolism
Institutions: Imperial College London, University of Copenhagen, Amager Hospital, Copenhagen University Hospital, Churchill Hospital, University of Oxford, NIHR Oxford Biomedical Research Centre, Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Birmingham, Eli Lilly (United States), Max Planck Institute for Medical Research, Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Novo Nordisk Foundation Center for Basic Metabolic Research
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $4,270
Funders: Eli Lilly and Company, Wellcome Trust, Saint Mary's Foundation, National Institute for Health and Care Research, Diabetes UK, Society for Endocrinology, European Commission, Novo Nordisk Fonden, Novo Nordisk Foundation Center for Basic Metabolic Research, HORIZON EUROPE Framework Programme, Medical Research Council, Economic and Social Research Council, European Research Council
Awards: G2850365055, G347855204, G4230908485, G4504918650, The role of biased agonism in the treatment of obesity, G514335088, G5267997313, G5784837116, Allosteric modulation of class B1 GPCRs via cholesterol binding sites, Molecular mechanisms underlying divergent incretin receptor responses in alpha versus beta cells
OpenAlex ID: W4417266039