Mechanical GPCR Activation by Traction Forces Exerted on Receptor N-Glycans.

Cells are sensitive to chemical stimulation which is converted into intracellular biochemical signals by the activation of specific receptors. Mechanical stimulations can also induce biochemical responses via the activation of various mechano-sensors. Although principally appreciated for their chemosensory function, G-protein-coupled receptors (GPCRs) may participate in mechano-transduction. They are indirectly activated by the paracrine release of chemical compounds secreted in response to mechanical stimuli, but they might additionally behave as mechano-sensors that are directly stimulated by mechanical forces. Although several studies are consistent with this latter hypothesis, the molecular mechanisms of a potential direct mechanical activation of GPCRs have remained elusive until recently. In particular, investigating the activation of the catecholamine β2-adrenergic receptor by a pathogen revealed that traction forces directly exerted on the N-terminus of the receptor via N-glycan chains activate specific signaling pathways. These findings open new perspectives in GPCR biology and pharmacology since most GPCRs express N-glycan chains in their N-terminus, which might similarly be involved in the interaction with cell-surface glycan-specific lectins in the context of cell-to-cell mechanical signaling.