Regulation of two‐pore‐domain (K_2P) potassium leak channels by the tyrosine kinase inhibitor genistein

Abstract

Background and purpose: Two-pore-domain potassium (K 2P ) channels mediate potassium background (or 'leak') currents, controlling excitability by stabilizing membrane potential below firing threshold and expediting repolarization. Inhibition of K 2P currents permits membrane potential depolarization and excitation. As expected for key regulators of excitability, leak channels are under tight control from a plethora of stimuli. Recently, signalling via protein tyrosine kinases (TKs) has been implicated in ion channel modulation. The objective of this study was to investigate TK regulation of K 2P channels. Experimental approach: The two-electrode voltage clamp technique was used to record K 2P currents in Xenopus oocytes. In addition, K 2P channels were studied in Chinese hamster ovary (CHO) cells using the whole-cell patch clamp technique. Key results: Here, we report inhibition of human K 2P 3.1 (TASK-1) currents by the TK antagonist, genistein, in Xenopus oocytes (IC 50 ¼ 10.7 mM) and in CHO cells (IC 50 ¼ 12.3 mM). The underlying molecular mechanism was studied in detail. hK 2P 3.1 was not affected by genistin, an inactive analogue of genistein. Perorthovanadate, an inhibitor of tyrosine phosphatase activity, reduced the inhibitory effect of genistein. Current reduction was voltage independent and did not require channel protonation at position H98 or phosphorylation at the single TK phosphorylation site, Y323. Among functional hK 2P family members, genistein also reduced K 2P 6.1 (TWIK-2), K 2P 9.1 (TASK-3) and K 2P 13.1 (THIK-1) currents, respectively. Conclusions and implications: Modulation of K 2P channels by the TK inhibitor, genistein, represents a novel molecular mechanism to alter background K þ currents.

Activation of the TASK-2 channel after cell swelling is dependent on tyrosine phosphorylation

“…It is thus clear that one or more tyrosine kinases are responsible for swellingactivation of the K ϩ channels, which in EATC and EATCC are known to be TASK-2 channels. It has previously been shown that TASK-1 background current is inhibited by genestein and that an inhibitor of protein tyrosine phosphatase reduces this effect (12). In the present investigation it is demonstrated that inhibition of tyrosine phosphatases prevents the inhibitory effect of the tyrosine kinase inhibitor genistein on RVD.…”

Physiological genomics identifies genetic modifiers of long QT syndrome type 2 severity

“…Twopore-domain potassium channel (K 2p ) genes such as KCNK17 (encoding K 2p 17.1, also known as TASK-4 and TALK-2) are known to be robustly expressed in myriad tissues, including cardiac and central nervous system, where they traditionally have been thought to regulate background cell excitability as leak channels (28,29). However, a wealth of transgenic animal studies support the notion that TASK family K 2p channels also strongly contribute to cardiac repolarization (30)(31)(32).…”

Mechanisms of zolpidem‐induced long QT syndrome: acute inhibition of recombinant hERG K+ channels and action potential prolongation in human cardiomyocytes derived from induced pluripotent stem cells

“…All experiments have been carried out in accordance with the United States National Institutes of Health Guide for the Care and Use of Laboratory Animals (NIH Publication no. 85-23, revised 1996) as reported earlier (Gierten et al, 2008;Staudacher et al, 2011b;Seyler et al, 2012). Briefly, oocytes were isolated from X. laevis ovarian lobes after surgical extirpation during tricaine anaesthesia (1 g L -1…”