A conserved conformation-dependent mechanism for the TREK two-pore domain potassium channel inhibitors carvedilol and fluphenazine.

The TREK subfamily of 2-pore domain potassium 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 2 TREK channel inhibitors: the β-blocker carvedilol and the antipsychotic fluphenazine. Using patch and 2-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 10-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. SIGNIFICANCE STATEMENT: TREK potassium channels play key roles in regulating membrane excitability in a wide range of cells. Modulation of these channels has been proposed for potential antiarrhythmic and antidepressant effects. This study defined the off-target molecular mechanism of action of the clinically used drugs carvedilol and fluphenazine on TREK channels and identify the TREK channel fenestration as a promiscuous binding site for inhibitory drugs.