DCPIB, an Inhibitor of Volume-Regulated Anion Channels, Distinctly Modulates K2P Channels

Abstract

K2P potassium channels stabilize the resting membrane potential in nearly all cells and have been implicated in several neuronal, cardiovascular, and immune diseases. DCPIB, a known specific and potent inhibitor of volume-regulated anion channels (VRAC), has been reported to activate TREK1 and TREK2 in astrocytes and in vitro recently. In the present study, we demonstrated DCPIB also voltage dependently activated TRAAK besides TREK1/TREK2, showing DCPIB activated all TREK subfamily members. In contrast, the compound potently inhibited several other K2P channels with no voltage dependence, including TRESK, TASK1, and TASK3. DCPIB displayed superior selectivity toward TRESK with an IC50 of 0.14 μM, demonstrating at least 100-fold higher affinity over TREK1/TRAAK channels. Furthermore, the impaired ion selectivity filter region greatly impaired the activating effect of DCPIB on TREK1 but not the inhibitory effect of DCPIB on TRESK. This indicates distinct molecular determinants underlying the effect of DCPIB on TREK1 or TRESK channels. Our results showed that DCPIB played diverse effects on K2P channels and could be a useful tool for further investigating structure–function studies of K2P channels.

LRRC8A is dispensable for a variety of microglial functions and response to acute stroke

“…As with any such another key point raised by our findings is that the current array of VRAC inhibitors are not sufficiently selective for this purpose. Indeed, we and others have demonstrated extensive undesirable off-target activity in even the current gold-standard inhibitor, DCPIB (Afzal et al, 2019;Lv et al, 2019;Minieri et al, 2013). As such, the discovery of compounds with greater selectivity for VRAC over other chloride channels would be of great benefit, both to better understand VRAC's roles in physiology and to explore its value as a therapeutic target.…”

The Volume-Regulated Anion Channel LRRC8/VRAC Is Dispensable for Cell Proliferation and Migration

“…Several studies reported an impairment of proliferation and/or migration of various cell lines in the presence of VRAC inhibitors [24,25,28,29,30,31,32,33,34,35,36,37,38]. However, the available VRAC inhibitors display little selectivity and often also inhibit other anion channels [55,56], or as in the case of the potent and relatively selective VRAC blocker DCPIB [57] even modulate potassium channels [58,59]. The identification of LRRC8 proteins as essential VRAC components [4,5] enabled investigating physiological functions of VRAC by molecular biological tools.…”

The LRRC8 volume‐regulated anion channel inhibitor, DCPIB, inhibits mitochondrial respiration independently of the channel

“…Unfortunately, DCPIB is unable to cross the blood–brain barrier when administered intravenously and suffers from poor selectivity (Zhang et al, ) DCPIB inhibits VRAC activity with an IC 50 of approximately 5 µM, making it the most potent and best‐in‐class VRAC inhibitor currently available. However, at concentrations used to inhibit VRAC, DCPIB also inhibits H‐K‐ATPase (Fujii et al, ), inward rectifier potassium (Kir) channels (Deng, Mahajan, Baumgarten, & Logothetis, ), two pore‐domain potassium (K2P) channels (Lv et al, ), glutamate release via connexin hemichannels (Bowens, Dohare, Kuo, & Mongin, ), and glutamate uptake by GLT‐1 glutamate transporters (Bowens et al, ). Indeed, the molecular pharmacology of VRAC is plagued by weak and non‐selective inhibitors.…”