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Minnion, J.

Publications and source records attributed to Minnion, J..

2 recordsLinked to original sources
bioRxiv2019

Disconnect between signalling potency and in vivo efficacy of pharmacokinetically optimised biased glucagon-like peptide-1 receptor agonists

ObjectiveTo determine how pharmacokinetically advantageous acylation impacts on glucagon-like peptide-1 receptor (GLP-1R) signal bias, trafficking, anti-hyperglycaemic efficacy and appetite suppression. MethodsIn vitro signalling responses were measured using biochemical and biosensor assays. GLP-1 receptor trafficking was determined by confocal microscopy and diffusion-enhanced resonance energy transfer. Pharmacokinetics, glucoregulatory effects and appetite suppression were measured in acute, sub-chronic and chronic settings in mice. ResultsA C-terminally acylated ligand, exendin-phe1-C16, was identified with undetectable {beta}-arrestin recruitment and GLP-1R internalisation. Depending on the cellular system used, this molecule was up to 1000-fold less potent than the comparator exendin-asp-3-C16 for cyclic AMP signalling, yet was considerably more effective in vivo, particularly for glucose regulation. ConclusionsC-terminal acylation of biased GLP-1R agonists increases their degree of signal bias in favour of cAMP production and improves their therapeutic potential.

pharmacology and toxicology↗
bioRxiv2019

Differences in signalling, trafficking and glucoregulatory properties of glucagon-like peptide-1 receptor agonists exendin-4 and lixisenatide

Background and purposeAmino acid substitutions at the N-termini of glucagon-like peptide-1 receptor agonist (GLP-1RA) peptides result in distinct patterns of intracellular signalling, sub-cellular trafficking and efficacy in vivo. Here we aimed to determine whether sequence differences at the ligand C-termini of clinically approved GLP-1RAs exendin-4 and lixisenatide lead to similar phenomena. We also sought to establish the impact of the C-terminus on signal bias resulting from modifications elsewhere in the molecule. Experimental approachExendin-4, lixisenatide, and N-terminally substituted analogues with biased signalling characteristics were compared across a range of in vitro trafficking and signalling assays in different cell types. Fluorescent ligands and new time-resolved FRET approaches were developed to study agonist behaviours at the cellular and sub-cellular level. Anti-hyperglycaemic and anorectic effects of each parent ligand, and their biased derivatives, were assessed in mice. Key resultsLixisenatide and exendin-4 showed equal binding affinity, but lixisenatide was 5-fold less potent for cAMP signalling. Both peptides were rapidly endocytosed, but the GLP-1R recycled more slowly to the plasma membrane after lixisenatide treatment. These combined deficits resulted in reduced maximal sustained insulin secretion and reduced anti-hyperglycaemic and anorectic effects in mice. N-terminal substitutions to both ligands had favourable effects on their pharmacology, resulting in improved insulin release and lowering of blood glucose. Conclusion and implicationsChanges to the C-terminus of exendin-4 affect signalling potency and GLP-1R trafficking via mechanisms unrelated to GLP-1R occupancy. These differences were associated with changes in their ability to control blood glucose and therefore may be therapeutically relevant.

pharmacology and toxicology↗