One drug-sensitive subunit is sufficient for a near-maximal retigabine effect in KCNQ channels

Yau, Michael C.; Kim, Robin Y.; Wang, Caroline K.; Li, Jingru; Ammar, Tarek; Yang, Runying; Pless, Stephan A.; Kurata, Harley T.

doi:10.1085/jgp.201812013

Cited by 12 publications

(22 citation statements)

References 44 publications

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“…Retigabine stabilizes the channels' open states as it increases the dwell time of open events (Tatulian and Brown, 2003;Syeda et al, 2015). Consistently, Retigabine also decreases the deactivation rate of K V 7.2/K V 7.3 channels (Main et al, 2000;Linley et al, 2012;Corbin-Leftwich et al, 2016;Yau et al, 2018). Furthermore, at the micromolar range of concentrations (<10 mM), Retigabine is more effective in decreasing the deactivation rate when K V 7.2/K V 7.3 channels have been long activated or when opened in steady state at typical neuronal resting potentials (Corbin-Leftwich et al, 2016).…”

Section: Pi(45)p 2 Depletion Hampers the Activity-dependent Stabilizmentioning

confidence: 64%

Modulation of KV7 Channel Deactivation by PI(4,5)P2

Villalba-Galea

2020

Front. Pharmacol.

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The activity of K V 7 channels critically contributes to the regulation of cellular electrical excitability in many cell types. In the central nervous system, the heteromeric K V 7.2/K V 7.3 channel is thought to be the chief molecular entity giving rise to M-currents. These K +-currents as so called because they are inhibited by the activation of Gq protein-coupled muscarinic receptors. In general, activation of Gq protein-coupled receptors (GqPCRs) decreases the concentration of the phosphoinositide PI(4,5)P 2 which is required for K V 7 channel activity. It has been recently reported that the deactivation rate of K V 7.2/K V 7.3 channels decreases as a function of activation. This suggests that the activated/open channel stabilizes as activation persists. This property has been regarded as evidence for the existence of modal behavior in the activity of these channels. In particular, it has been proposed that the heteromeric K V 7.2/ K V 7.3 channel has at least two modes of activity that can be distinguished by both their deactivation kinetics and sensitivity to Retigabine. The current study was aimed at understanding the effect of PI(4,5)P 2 depletion on the modal behavior of K V 7.2/K V 7.3 channels. Here, it was hypothesized that depleting the membrane of P(4,5)P 2 would hamper the stabilization of the activated/open channel, resulting in higher rates of deactivation of the heteromeric K V 7.2/K V 7.3 channel. In addressing this question, it was found that the activity-dependent slowdown of the deactivation was not as prominent when channels were co-expressed with the chimeric phosphoinositide-phosphatase Ci-VS-TPIP or when cells were treated with the phosphoinositide kinase inhibitor Wortmannin. Further, it was observed that either of these approaches to deplete PI(4,5)P 2 had a higher impact on the kinetic of deactivation following prolonged activation, while having little or no effect when activation was short-lived. Furthermore, it was observed that the action of either Ci-VS-TPIP or Wortmannin reduced the effect of Retigabine on the kinetics of deactivation, having a higher impact when activation was prolonged. These combined observations led to the conclusion that the deactivation kinetic of K V 7.2/K V 7.3 channels was sensitive to PI(4,5)P 2 depletion in an activation-dependent manner, displaying a stronger effect on deactivation following prolonged activation.

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Section: Pi(45)p 2 Depletion Hampers the Activity-dependent Stabilizmentioning

confidence: 64%

Modulation of KV7 Channel Deactivation by PI(4,5)P2

Villalba-Galea

2020

Front. Pharmacol.

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“…Our previous studies also show that 3 residues, Val224, Val225, and Tyr226 in Kv7.2, are important for opener QO-58-mediated activation of the channel (32). RTG requires only 1 drug-sensitive subunit to generate its full effect on activating Kv7 tetramers, whereas another selective Kv7.2/7.3 opener, N-(2-chloro-5-pyrimidinyl)-3,4-difluorobenzamide, requires 4 drug-sensitive subunits for channel activation (49,50). Consistent with these findings, our data also show that SCR2682 no longer enhances the current amplitude or shifts the voltagedependent activation of Kv7.2 W236L mutant, whereas our previously identified Kv7.2/Kv7.3 opener QO-58 still causes a significant leftward shift of the voltage-dependent activation of the Kv7.2 W236L mutant channel (39).…”

Section: Discussionmentioning

confidence: 98%

Electrophysiological and pharmacological characterization of a novel and potent neuronal Kv7 channel opener SCR2682 for antiepilepsy

et al. 2019

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Voltage‐gated Kv7/KCNQ/M potassium channels play an essential role in the control of membrane potential and neuronal excitability. Activation of the neuronal Kv7/KCNQ/M‐current represents an attractive therapeutic strategy for treatment of hyperexcitability‐related neuropsychiatric disorders such as epilepsy, pain, and depression, which is an unmet medical need. In this study, we synthesized and characterized a novel compound, N‐(4‐(2‐bromo‐6,7‐dihydrothieno[3,2‐c]pyridin‐5(4H)‐yl)‐2,6‐dimethylphenyl)‐3,3‐dimethylbutanamide (SCR2682) 2,6‐dimethyl‐4‐(piperidin‐yl) phenyl)‐amide derivative, that exhibits selective and potent activation of neuronal Kv7/KCNQ/M‐channels. Whole‐cell patch‐clamp recordings of human embryonic kidney 293 cells expressing Kv7.2/Kv7.3 channels show that SCR2682 selectively activates the channel current in a dose‐dependent manner with an EC50 of 9.8 ± 0.4 nM, which is ∼100‐fold more potent than a U.S. Food and Drug Administration–approved antiepileptic drug (retigabine) for treatment of partial epilepsy. SCR2682 shifts voltage‐dependent activation of the Kv7.2/7.3 current toward more negative membrane potential, to about −37 mV (V1/2). SCR2682 also activates the native M‐current in rat hippocampal or cortical neurons, causing marked hyperpolarization and potent inhibition of neuronal firings. Mechanistically, mutating the tryptophan residue 236 located at the fifth transmembrane segment of Kv7.2 abolishes the chemical activation of the channel by SCR2682. Furthermore, intraperitoneal or intragastric administration of SCR2682 results in a dose‐dependent inhibition of seizures by maximal electroshock. Taken together, our findings demonstrate that a novel small molecule, SCR2682, selectively and potently activates neuronal Kv7 channels and reverses epileptic seizures in rodents. Thus, SCR2682 may warrant further evaluation for clinical development of antiepileptic therapy.—Zhang, F., Liu, Y., Tang, F., Liang, B., Chen, H., Zhang, H., Wang, K. Electrophysiological and pharmacological characterization of a novel and potent neuronal Kv7 channel opener SCR2682 for antiepilepsy. FASEB J. 33, 9154–9166 (2019). http://www.fasebj.org

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“…Recent work from the Kurata laboratory utilized concatenated kcnq2 and kcnq3 constructs to determine whether Kv7 channel activating drugs exert their effects by binding to individual α-subunits, or by binding to multiple α-subunits within the tetrameric channel structures ( Wang et al, 2018 ; Yau et al, 2018 ). They utilized mutations that prevent the drug effects to determine that retigabine, a Kv7 channel activator, need interact with only a single retigabine-sensitive α-subunit within a tetrameric Kv7.3 channel to exert its full effect ( Wang et al, 2018 ), whereas another Kv7 channel activator, ICA-069673, required four responsive α-subunits within Kv7.2 channels for its full response ( Yau et al, 2018 ). Although these studies demonstrated that concatenated Kv7 channels are functional in an expression system ( Xenopus oocytes), the physiological regulation of the channels was not explored.…”

Section: Discussionmentioning

confidence: 99%

Section: Concatenated α-Subunits As a Model To Study Kv Channel Strucmentioning

confidence: 99%

“…They utilized mutations that prevent the drug effects to determine that retigabine, a Kv7 channel activator, need interact with only a single retigabine-sensitive α-subunit within a tetrameric Kv7.3 channel to exert its full effect (Wang et al, 2018), whereas another Kv7 channel activator, ICA-069673, required four responsive α-subunits within Kv7.2 channels for its full response (Yau et al, 2018). Although these studies demonstrated that concatenated Kv7 channels are functional in an expression system (Xenopus oocytes), the physiological regulation of the channels was not explored.…”

Section: Concatenated α-Subunits As a Model To Study Kv Channel Strucmentioning

confidence: 99%

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Heteromeric Channels Formed From Alternating Kv7.4 and Kv7.5 α-Subunits Display Biophysical, Regulatory, and Pharmacological Characteristics of Smooth Muscle M-Currents

2020

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Smooth muscle cells of the vasculature, viscera, and lungs generally express multiple α-subunits of the Kv7 voltage-gated potassium channel family, with increasing evidence that both Kv7.4 and Kv7.5 can conduct "M-currents" that are functionally important for the regulation of smooth muscle contractility. Although expression systems demonstrate that functional channels can form as homomeric tetramers of either Kv7.4 or Kv7.5 α-subunits, there is evidence that heteromeric channel complexes, containing some combination of Kv7.4 and Kv7.5 α-subunits, may represent the predominant configuration natively expressed in some arterial myocytes, such as rat mesenteric artery smooth muscle cells (MASMCs). Our previous work has suggested that Kv7.4/Kv7.5 heteromers can be distinguished from Kv7.4 or Kv7.5 homomers based on their biophysical, regulatory, and pharmacological characteristics, but it remains to be determined how Kv7.4 and Kv7.5 α-subunits combine to produce these distinct characteristics. In the present study, we constructed concatenated dimers or tetramers of Kv7.4 and Kv7.5 α-subunits and expressed them in a smooth muscle cell line to determine if a particular α-subunit configuration can exhibit the features previously reported for natively expressed Kv7 currents in MASMCs. Several unique characteristics of native smooth muscle M-currents were reproduced under conditions that constrain channel formation to a Kv7.4:Kv7.5 stoichiometry of 2:2, with alternating Kv7.4 and Kv7.5 α-subunits within a tetrameric structure. Although other subunit arrangements/combinations are not ruled out, the findings provide new insights into the oligomerization of α-subunits and the ways in which Kv7.4/Kv7.5 subunit assembly can affect smooth muscle signal transduction and pharmacological responses to Kv7 channel modulating drugs.

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One drug-sensitive subunit is sufficient for a near-maximal retigabine effect in KCNQ channels

Cited by 12 publications

References 44 publications

Modulation of KV7 Channel Deactivation by PI(4,5)P2

Modulation of KV7 Channel Deactivation by PI(4,5)P2

Electrophysiological and pharmacological characterization of a novel and potent neuronal Kv7 channel opener SCR2682 for antiepilepsy

Heteromeric Channels Formed From Alternating Kv7.4 and Kv7.5 α-Subunits Display Biophysical, Regulatory, and Pharmacological Characteristics of Smooth Muscle M-Currents

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