Mechano-sensitivity of β2-adrenoceptors enhances constitutive activation of cAMP generation that is inhibited by inverse agonists

Cullum, Sean A.; Platt, Simon; Dale, Natasha; Isaac, Oliver C.; Wragg, Edward S.; Soave, Mark; Veprintsev, Dmitry B.; Woolard, Jeanette; Kilpatrick, Laura E.; Hill, Stephen J.

Abstract

The concept of agonist-independent signalling that can be attenuated by inverse agonists is a fundamental element of the cubic ternary complex model of G protein-coupled receptor (GPCR) activation. This model shows how a GPCR can exist in two conformational states in the absence of ligands; an inactive R state and an active R* state that differ in their affinities for agonists, inverse agonists, and G-protein alpha subunits. The proportion of R* receptors that exist in the absence of agonists determines the level of constitutive receptor activity. In this study we demonstrate that mechanical stimulation can induce β2-adrenoceptor agonist-independent Gs-mediated cAMP signalling that is sensitive to inhibition by inverse agonists such as ICI-118551 and propranolol. The size of the mechano-sensitive response is dependent on the cell surface receptor expression level in HEK293G cells, is still observed in a ligand-binding deficient D113A mutant β2-adrenoceptor and can be attenuated by site-directed mutagenesis of the extracellular N-glycosylation sites on the N-terminus and second extracellular loop of the β2-adrenoceptor. Similar mechano-sensitive agonist-independent responses are observed in HEK293G cells overexpressing the A2A-adenosine receptor. These data provide new insights into how agonist-independent constitutive receptor activity can be enhanced by mechanical stimulation and regulated by inverse agonists.

Citation

Cullum, S. A., Platt, S., Dale, N., Isaac, O. C., Wragg, E. S., Soave, M., Veprintsev, D. B., Woolard, J., Kilpatrick, L. E., & Hill, S. J. (2024). Mechano-sensitivity of β2-adrenoceptors enhances constitutive activation of cAMP generation that is inhibited by inverse agonists. Communications Biology, 7(1), Article 417. https://doi.org/10.1038/s42003-024-06128-2

• Journal Article Type: Article
• Acceptance Date: Mar 29, 2024
• Online Publication Date: Apr 5, 2024
• Publication Date: Apr 5, 2024
• Deposit Date: Apr 5, 2024
• Publicly Available Date: Apr 8, 2024
• Journal: Communications Biology
• Electronic ISSN: 2399-3642
• Publisher: Nature Publishing Group
• Peer Reviewed: Peer Reviewed
• Volume: 7
• Issue: 1
• Article Number: 417
• DOI: https://doi.org/10.1038/s42003-024-06128-2
• Keywords: Pharmacodynamics; Receptor pharmacology
• Public URL: https://nottingham-repository.worktribe.com/output/33293816
• Publisher URL: https://www.nature.com/articles/s42003-024-06128-2