Abstract
Mechanically activated Piezo2 channels are key players in somatosensory touch, but their regulation by cellular signaling pathways is poorly understood. Dorsal root ganglion (DRG) neurons express a variety of G-protein-coupled receptors that modulate the function of sensory ion channels. Gi-coupled receptors are generally considered inhibitory, as they usually decrease excitability. Paradoxically, activation of Gi-coupled receptors in DRG neurons sometimes induces mechanical hypersensitivity, the mechanism of which is not well understood. Here, we find that activation of Gi-coupled receptors potentiates mechanically activated currents in DRG neurons and heterologously expressed Piezo2 channels, but inhibits Piezo1 currents in heterologous systems in a Gβγ-dependent manner. Pharmacological inhibition of kinases downstream of Gβγ, phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) also abolishes the potentiation of Piezo2 currents. Local injection of sumatriptan, an agonist of the Gi-coupled serotonin 1B/1D receptors, increases mechanical sensitivity in mice, and the effect is abolished by inhibiting PI3K and MAPK. Hence, our studies illustrate an indirect mechanism of action of Gβγ to sensitize Piezo2 currents and alter mechanosensitivity after activation of Gi-coupled receptors.
Keywords:
MAPK; G-protein βγ; Gi-coupled receptors; PI3K; Piezo2.