A conserved conformation-dependent mechanism for the TREK K2P channel inhibitors carvedilol and fluphenazine

The TREK subfamily of Two-Pore Domain Potassium (K2P) channels act as polymodal sensors of multiple physical and chemical stimuli, coupling electrical excitability to the cellular environment. A nuanced understanding of TREK channel pharmacology is necessary for the development of novel experimental tools, for potential pharmacotherapies, and for understanding potential beneficial or adverse effects of clinically used drugs. Here we sought to determine the mechanism of action of two TREK channel inhibitors: the beta-blocker carvedilol and the anti-psychotic fluphenazine. Using patch and two-electrode voltage clamp electrophysiology, we show that both carvedilol and fluphenazine exhibit an activation-mode dependence, with mechanical- and temperature-activation of TREK channels reducing drug sensitivity approximately ten-fold. Mutagenesis at a key intramembrane fenestration site leucine, modulator competition experiments, and in silico docking studies are all consistent with carvedilol and fluphenazine binding at a shared, overlapping binding site. These findings establish a conserved conformation-dependent mechanism of action for structurally diverse TREK inhibitors and identify the fenestration as a promiscuous binding site for a range of clinically used drugs.