A High-Throughput Functional Screen Identifies Small Molecule Regulators of Temperature- and Mechano-Sensitive K2P Channels

K-2P (KCNK) potassium channels generate "leak" potassium currents that strongly influence cellular excitability and contribute to pain, somatosensation, anesthesia, and mood. Despite their physiological importance, K(2P)s lack specific pharmacology. Addressing this issue has been complicated by the challenges that the leak nature of K-2P currents poses for electrophysiology-based high-throughput screening strategies. Here, we present a yeast-based high-throughput screening assay that avoids this problem. Using a simple growth-based functional readout, we screened a library of 106,281 small molecules and identified two new inhibitors and three new activators of the mammalian K-2P channel K(2P)2.1 (KCNK2, TREK-1). By combining biophysical, structure-activity, and mechanistic analysis, we developed a dihydroacridine analogue, ML67-33, that acts as a low micromolar, selective activator of temperature- and mechano-sensitive K-2P channels. Biophysical studies show that ML67-33 reversibly increases channel currents by activating the extracellular selectivity filter-based C-type gate that forms the core gating apparatus on which a variety of diverse modulatory inputs converge. The new K-2P modulators presented here, together with the yeast-based assay, should enable both mechanistic and physiological studies of K-2P activity and facilitate the discovery and development of other K-2P small molecule modulators.