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Oyama M, Watanabe S, Iwai T, Tanabe M. Selective inhibition of A-fiber-mediated excitatory transmission underlies the analgesic effects of KCNQ channel opening in the spinal dorsal horn. Neuropharmacology 2024; 254:109994. [PMID: 38750803 DOI: 10.1016/j.neuropharm.2024.109994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2024] [Revised: 04/11/2024] [Accepted: 05/10/2024] [Indexed: 05/18/2024]
Abstract
Neuronal voltage-gated KCNQ (Kv7) channels, expressed centrally and peripherally, mediate low-threshold and non-inactivating M-currents responsible for the control of tonic excitability of mammalian neurons. Pharmacological opening of KCNQ channels has been reported to generate analgesic effects in animal models of neuropathic pain. Here, we examined the possible involvement of central KCNQ channels in the analgesic effects of retigabine, a KCNQ channel opener. Behaviorally, intraperitoneally applied retigabine exerted analgesic effects on thermal and mechanical hypersensitivity in male mice developing neuropathic pain after partial sciatic nerve ligation, which was antagonized by the KCNQ channel blocker XE991 preadministered intraperitoneally and intrathecally. Intrathecally applied retigabine also exerted analgesic effects that were inhibited by intrathecally injected XE991. We then explored the synaptic mechanisms underlying the analgesic effects of retigabine in the spinal dorsal horn. Whole-cell recordings were made from dorsal horn neurons in spinal slices with attached dorsal roots from adult male mice developing neuropathic pain, and the effects of retigabine on miniature and afferent-evoked postsynaptic currents were examined. Retigabine reduced the amplitude of A-fiber-mediated EPSCs without affecting C-fiber-mediated excitatory synaptic transmission. A-fiber-mediated EPSCs remained unaltered by retigabine in the presence of XE991, consistently with the behavioral findings. The frequency and amplitude of mEPSCs were not affected by retigabine. Thus, opening of KCNQ channels in the central terminals of primary afferent A-fibers inhibits excitatory synaptic transmission in the spinal dorsal horn, most likely contributing to the analgesic effect of retigabine.
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Affiliation(s)
- Misa Oyama
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
| | - Shun Watanabe
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
| | - Takashi Iwai
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan
| | - Mitsuo Tanabe
- Laboratory of Pharmacology, School of Pharmaceutical Sciences, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan; Medicinal Research Laboratories, School of Pharmacy, Kitasato University, 5-9-1 Shirokane, Minato-ku, Tokyo, 108-8641, Japan.
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2
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Martin HR, Lysakowski A, Eatock RA. The potassium channel subunit K V1.8 ( Kcna10) is essential for the distinctive outwardly rectifying conductances of type I and II vestibular hair cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.11.21.563853. [PMID: 38045305 PMCID: PMC10690164 DOI: 10.1101/2023.11.21.563853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
In amniotes, head motions and tilt are detected by two types of vestibular hair cells (HCs) with strikingly different morphology and physiology. Mature type I HCs express a large and very unusual potassium conductance, gK,L, which activates negative to resting potential, confers very negative resting potentials and low input resistances, and enhances an unusual non-quantal transmission from type I cells onto their calyceal afferent terminals. Following clues pointing to KV1.8 (KCNA10) in the Shaker K channel family as a candidate gK,L subunit, we compared whole-cell voltage-dependent currents from utricular hair cells of KV1.8-null mice and littermate controls. We found that KV1.8 is necessary not just for gK,L but also for fast-inactivating and delayed rectifier currents in type II HCs, which activate positive to resting potential. The distinct properties of the three KV1.8-dependent conductances may reflect different mixing with other KV subunits that are reported to be differentially expressed in type I and II HCs. In KV1.8-null HCs of both types, residual outwardly rectifying conductances include KV7 (KCNQ) channels. Current clamp records show that in both HC types, KV1.8-dependent conductances increase the speed and damping of voltage responses. Features that speed up vestibular receptor potentials and non-quantal afferent transmission may have helped stabilize locomotion as tetrapods moved from water to land.
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Affiliation(s)
| | - Anna Lysakowski
- University of Illinois at Chicago, Department of Anatomy and Cell Biology
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3
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Krüger J, Lerche H. Retigabine and gabapentin restore channel function and neuronal firing in a cellular model of an epilepsy-associated dominant-negative KCNQ5 variant. Neuropharmacology 2024; 250:109892. [PMID: 38428481 DOI: 10.1016/j.neuropharm.2024.109892] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/19/2024] [Accepted: 02/26/2024] [Indexed: 03/03/2024]
Abstract
KCNQ5 encodes the voltage-gated potassium channel KV7.5, a member of the KV7 channel family, which conducts the M-current. This current is a potent regulator of neuronal excitability by regulating membrane potential in the subthreshold range of action potentials and mediating the medium and slow afterhyperpolarization. Recently, we have identified five loss-of-function variants in KCNQ5 in patients with genetic generalized epilepsy. Using the most severe dominant-negative variant (R359C), we set out to investigate pharmacological therapeutic intervention by KV7 channel openers on channel function and neuronal firing. Retigabine and gabapentin increased R359C-derived M-current amplitudes in HEK cells expressing homomeric or heteromeric mutant KV7.5 channels. Retigabine was most effective in restoring K+ currents. Ten μM retigabine was sufficient to reach the level of WT currents without retigabine, whereas 100 μM of gabapentin showed less than half of this effect and application of 50 μM ZnCl2 only significantly increased M-current amplitude in heteromeric channels. Overexpression of KV7.5-WT potently inhibited neuronal firing by increasing the M-current, whereas R359C overexpression had the opposite effect and additionally decreased the medium afterhyperpolarization current. Both aforementioned drugs and Zn2+ reversed the effect of R359C expression by reducing firing to nearly normal levels at high current injections. Our study shows that a dominant-negative variant with a complete loss-of-function in KV7.5 leads to largely increased neuronal firing which may explain a neuronal hyperexcitability in patients. KV7 channel openers, such as retigabine or gabapentin, could be treatment options for patients currently displaying pharmacoresistant epilepsy and carrying loss-of-function variants in KCNQ5.
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Affiliation(s)
- Johanna Krüger
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 27, 72076, Tübingen, Germany.
| | - Holger Lerche
- Department of Neurology and Epileptology, Hertie Institute for Clinical Brain Research, University of Tübingen, Otfried-Müller-Straße 27, 72076, Tübingen, Germany.
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Tian G, Bartas K, Hui M, Chen L, Vasquez JJ, Azouz G, Derdeyn P, Manville RW, Ho EL, Fang AS, Li Y, Tyler I, Setola V, Aoto J, Abbott GW, Beier KT. Molecular and circuit determinants in the globus pallidus mediating control of cocaine-induced behavioral plasticity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.29.596557. [PMID: 38853899 PMCID: PMC11160764 DOI: 10.1101/2024.05.29.596557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
The globus pallidus externus (GPe) is a central component of the basal ganglia circuit, receiving strong input from the indirect pathway and regulating a variety of functions, including locomotor output and habit formation. We recently showed that it also acts as a gatekeeper of cocaine-induced behavioral plasticity, as inhibition of parvalbumin-positive cells in the GPe (GPe PV ) prevents the development of cocaine-induced reward and sensitization. However, the molecular and circuit mechanisms underlying this function are unknown. Here we show that GPe PV cells control cocaine reward and sensitization by inhibiting GABAergic neurons in the substantia nigra pars reticulata (SNr GABA ), and ultimately, selectively modulating the activity of ventral tegmental area dopamine (VTA DA ) cells projecting to the lateral shell of the nucleus accumbens (NAcLat). A major input to GPe PV cells is the indirect pathway of the dorsomedial striatum (DMS D 2 ), which receives DAergic innervation from collaterals of VTA DA →NAcLat cells, making this a closed-loop circuit. Cocaine likely facilitates reward and sensitization not directly through actions in the GPe, but rather in the upstream DMS, where the cocaine-induced elevation of DA triggers a depression in DMS D 2 cell activity. This cocaine-induced elevation in DA levels can be blocked by inhibition of GPe PV cells, closing the loop. Interestingly, the level of GPe PV cell activity prior to cocaine administration is correlated with the extent of reward and sensitization that animals experience in response to future administration of cocaine, indicating that GPe PV cell activity is a key predictor of future behavioral responses to cocaine. Single nucleus RNA-sequencing of GPe cells indicated that genes encoding voltage-gated potassium channels KCNQ3 and KCNQ5 that control intrinsic cellular excitability are downregulated in GPe PV cells following a single cocaine exposure, contributing to the elevation in GPe PV cell excitability. Acutely activating channels containing KCNQ3 and/or KCNQ5 using the small molecule carnosic acid, a key psychoactive component of Salvia rosmarinus (rosemary) extract, reduced GPe PV cell excitability and also impaired cocaine reward, sensitization, and volitional cocaine intake, indicating its potential as a therapeutic to counteract psychostimulant use disorder. Our findings illuminate the molecular and circuit mechanisms by which the GPe orchestrates brain-wide changes in response to cocaine that are required for reward, sensitization, and self-administration behaviors.
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Sun H, Undem BJ. Selective KCNQ2/3 Potassium Channel Opener ICA-069673 Inhibits Excitability in Mouse Vagal Sensory Neurons. J Pharmacol Exp Ther 2024; 389:118-127. [PMID: 38290975 PMCID: PMC10949160 DOI: 10.1124/jpet.123.001959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/03/2024] [Accepted: 01/18/2024] [Indexed: 02/01/2024] Open
Abstract
Heightened excitability of vagal sensory neurons in inflammatory visceral diseases contributes to unproductive and difficult-to-treat neuronally based symptoms such as visceral pain and dysfunction. Identification of targets and modulators capable of regulating the excitability of vagal sensory neurons may lead to novel therapeutic options. KCNQ1-KCNQ5 genes encode KV7.1-7.5 potassium channel α-subunits. Homotetrameric or heterotetrameric KV7.2-7.5 channels can generate the so-called M-current (IM) known to decrease the excitability of neurons including visceral sensory neurons. This study aimed to address the hypothesis that KV7.2/7.3 channels are key regulators of vagal sensory neuron excitability by evaluating the effects of KCNQ2/3-selective activator, ICA-069673, on IM in mouse nodose neurons and determining its effects on excitability and action potential firings using patch clamp technique. The results showed that ICA-069673 enhanced IM density, accelerated the activation, and delayed the deactivation of M-channels in a concentration-dependent manner. ICA-069673 negatively shifted the voltage-dependent activation of IM and increased the maximal conductance. Consistent with its effects on IM, ICA-069673 induced a marked hyperpolarization of resting potential and reduced the input resistance. The hyperpolarizing effect was more pronounced in partially depolarized neurons. Moreover, ICA-069673 caused a 3-fold increase in the minimal amount of depolarizing current needed to evoke an action potential, and significantly limited the action potential firings in response to sustained suprathreshold stimulations. ICA-069673 had no effect on membrane currents when Kcnq2 and Kcnq3 were deleted. These results indicate that opening KCNQ2/3-mediated M-channels is sufficient to suppress the excitability and enhance spike accommodation in vagal visceral sensory neurons. SIGNIFICANCE STATEMENT: This study supports the hypothesis that selectively activating KCNQ2/3-mediated M-channels is sufficient to suppress the excitability and action potential firings in vagal sensory neurons. These results provide evidence in support of further investigations into the treatment of various visceral disorders that involve nociceptor hyperexcitability with selective KCNQ2/3 M-channel openers.
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Affiliation(s)
- Hui Sun
- Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Bradley J Undem
- Division of Allergy and Clinical Immunology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
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Lai H, Gao M, Yang H. The potassium channels: Neurobiology and pharmacology of tinnitus. J Neurosci Res 2024; 102:e25281. [PMID: 38284861 DOI: 10.1002/jnr.25281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 10/27/2023] [Accepted: 11/16/2023] [Indexed: 01/30/2024]
Abstract
Tinnitus is a widespread public health issue that imposes a significant social burden. The occurrence and maintenance of tinnitus have been shown to be associated with abnormal neuronal activity in the auditory pathway. Based on this view, neurobiological and pharmacological developments in tinnitus focus on ion channels and synaptic neurotransmitter receptors in neurons in the auditory pathway. With major breakthroughs in the pathophysiology and research methodology of tinnitus in recent years, the role of the largest family of ion channels, potassium ion channels, in modulating the excitability of neurons involved in tinnitus has been increasingly demonstrated. More and more potassium channels involved in the neural mechanism of tinnitus have been discovered, and corresponding drugs have been developed. In this article, we review animal (mouse, rat, hamster, and guinea-pig), human, and genetic studies on the different potassium channels involved in tinnitus, analyze the limitations of current clinical research on potassium channels, and propose future prospects. The aim of this review is to promote the understanding of the role of potassium ion channels in tinnitus and to advance the development of drugs targeting potassium ion channels for tinnitus.
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Affiliation(s)
- Haohong Lai
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Minqian Gao
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Hearing and Speech-Language Science, Guangzhou Xinhua University, Guangzhou, China
| | - Haidi Yang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Hearing and Speech-Language Science, Guangzhou Xinhua University, Guangzhou, China
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Sinha AK, Lee C, Holt JC. KCNQ2/3 regulates efferent mediated slow excitation of vestibular afferents in mammals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.12.30.573731. [PMID: 38260489 PMCID: PMC10802244 DOI: 10.1101/2023.12.30.573731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Primary vestibular afferents transmit information from hair cells about head position and movement to the CNS, which is critical for maintaining balance, gaze stability and spatial navigation. The CNS, in turn, modulates hair cells and afferents via the efferent vestibular system (EVS) and its activation of several cholinergic signaling mechanisms. Electrical stimulation of EVS neurons gives rise to three kinetically- and mechanistically-distinct afferent responses including a slow excitation, a fast excitation, and a fast inhibition. EVS-mediated slow excitation is attributed to odd-numbered muscarinic acetylcholine receptors (mAChRs) on the afferent whose activation leads to the closure of a potassium conductance and increased afferent discharge. Likely effector candidates include low-threshold, voltage-gated potassium channels belonging to the KCNQ (Kv7.X) family, which are involved in neuronal excitability across the nervous system and are subject to mAChR modulation. Specifically, KCNQ2/3 heteromeric channels may be the molecular correlates for the M-current, a potassium current that is blocked following the activation of odd-numbered mAChRs. To this end, multiple members of the KCNQ channel family, including KCNQ2 and KCNQ3, are localized to several microdomains within vestibular afferent endings, where they influence afferent excitability and could be targeted by EVS neurons. Additionally, the relative expression of KCNQ subunits appears to vary across the sensory epithelia and among different afferent types. However, it is unclear which KCNQ channel subunits are targeted by mAChR activation and whether that also varies among different afferent classes. Here we show that EVS-mediated slow excitation is blocked and enhanced by the non-selective KCNQ channel blocker XE991 and opener retigabine, respectively. Using KCNQ subunit-selective drugs, we observed that a KCNQ2 blocker blocks the slow response in irregular afferents, while a KCNQ2/3 opener enhances slow responses in regular afferents. The KCNQ2 blockers did not appear to affect resting afferent discharge rates, while KCNQ2/3 or KCNQ2/4 openers decreased afferent excitability. Here, we show pharmacological evidence that KCNQ2/3 subunits are likely targeted by mAChR activation in mammalian vestibular afferents. Additionally, we show that KCNQ3 KO mice have altered resting discharge rate as well as EVS-mediated slow response. These data together suggest that KCNQ channels play a role in slow response and discharge rate of vestibular afferents, which can be modulated by EVS in mammals.
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Huang Y, Ma D, Yang Z, Zhao Y, Guo J. Voltage-gated potassium channels KCNQs: Structures, mechanisms, and modulations. Biochem Biophys Res Commun 2023; 689:149218. [PMID: 37976835 DOI: 10.1016/j.bbrc.2023.149218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 10/19/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023]
Abstract
KCNQ (Kv7) channels are voltage-gated, phosphatidylinositol 4,5-bisphosphate- (PIP2-) modulated potassium channels that play essential roles in regulating the activity of neurons and cardiac myocytes. Hundreds of mutations in KCNQ channels are closely related to various cardiac and neurological disorders, such as long QT syndrome, epilepsy, and deafness, which makes KCNQ channels important drug targets. During the past several years, the application of single-particle cryo-electron microscopy (cryo-EM) technique in the structure determination of KCNQ channels has greatly advanced our understanding of their molecular mechanisms. In this review, we summarize the currently available structures of KCNQ channels, analyze their special voltage gating mechanism, and discuss their activation mechanisms by both the endogenous membrane lipid and the exogenous synthetic ligands. These structural studies of KCNQ channels will guide the development of drugs targeting KCNQ channels.
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Affiliation(s)
- Yuan Huang
- Department of Cardiology, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Demin Ma
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Zhenni Yang
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China
| | - Yiwen Zhao
- The Key Laboratory of Neural and Vascular Biology, The Key Laboratory of New Drug Pharmacology and Toxicology, Department of Pharmacology, Ministry of Education, Hebei Medical University, Shijiazhuang, 050011, China
| | - Jiangtao Guo
- Department of Biophysics and Department of Neurology of the Fourth Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, 310058, China.
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Liu E, Pang K, Liu M, Tan X, Hang Z, Mu S, Han W, Yue Q, Comai S, Sun J. Activation of Kv7 channels normalizes hyperactivity of the VTA-NAcLat circuit and attenuates methamphetamine-induced conditioned place preference and sensitization in mice. Mol Psychiatry 2023; 28:5183-5194. [PMID: 37604975 DOI: 10.1038/s41380-023-02218-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Revised: 08/02/2023] [Accepted: 08/04/2023] [Indexed: 08/23/2023]
Abstract
The brain circuit projecting from the ventral tegmental area (VTA) to the nucleus accumbens lateral shell (NAcLat) has a key role in methamphetamine (MA) addiction. As different dopamine (DA) neuron subpopulations in the VTA participate in different neuronal circuits, it is a challenge to isolate these DA neuron subtypes. Using retrograde tracing and Patch-seq, we isolated DA neurons in the VTA-NAcLat circuit in MA-treated mice and performed gene expression profiling. Among the differentially expressed genes, KCNQ genes were dramatically downregulated. KCNQ genes encode Kv7 channel proteins, which modulate neuronal excitability. Injection of both the Kv7.2/3 agonist ICA069673 and the Kv7.4 agonist fasudil into the VTA attenuated MA-induced conditioned place preference and locomotor sensitization and decreased neuronal excitability. Increasing Kv7.2/3 activity decreased neural oscillations, synaptic plasticity and DA release in the VTA-NacLat circuit in MA-treated mice. Furthermore, overexpression of only Kv7.3 channels in the VTA-NacLat circuit was sufficient to attenuate MA-induced reward behavior and decrease VTA neuron excitability. Activation of Kv7 channels in the VTA may become a novel treatment strategy for MA abuse.
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Affiliation(s)
- E Liu
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Kunkun Pang
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
- Department of Ultrasound, The Second Hospital of Shandong University, Jinan, Shandong, China
| | - Min Liu
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Xu Tan
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Zhaofang Hang
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Shouhong Mu
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Weikai Han
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Qingwei Yue
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China
| | - Stefano Comai
- Department of Psychiatry, McGill University, Montréal, QC, Canada
- Department of Pharmaceutical and Pharmacological Sciences, University of Padua, Padua, Italy
- Department of Biomedical Sciences, University of Padua, Padua, Italy
| | - Jinhao Sun
- Department of Anatomy and Neurobiology, Shandong University School of Basic Medicine, Jinan, Shandong, China.
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Bortolami A, Sesti F. Ion channels in neurodevelopment: lessons from the Integrin-KCNB1 channel complex. Neural Regen Res 2023; 18:2365-2369. [PMID: 37282454 PMCID: PMC10360111 DOI: 10.4103/1673-5374.371347] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023] Open
Abstract
Ion channels modulate cellular excitability by regulating ionic fluxes across biological membranes. Pathogenic mutations in ion channel genes give rise to epileptic disorders that are among the most frequent neurological diseases affecting millions of individuals worldwide. Epilepsies are triggered by an imbalance between excitatory and inhibitory conductances. However, pathogenic mutations in the same allele can give rise to loss-of-function and/or gain-of-function variants, all able to trigger epilepsy. Furthermore, certain alleles are associated with brain malformations even in the absence of a clear electrical phenotype. This body of evidence argues that the underlying epileptogenic mechanisms of ion channels are more diverse than originally thought. Studies focusing on ion channels in prenatal cortical development have shed light on this apparent paradox. The picture that emerges is that ion channels play crucial roles in landmark neurodevelopmental processes, including neuronal migration, neurite outgrowth, and synapse formation. Thus, pathogenic channel mutants can not only cause epileptic disorders by altering excitability, but further, by inducing morphological and synaptic abnormalities that are initiated during neocortex formation and may persist into the adult brain.
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Affiliation(s)
- Alessandro Bortolami
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, West Piscataway, NJ, USA
| | - Federico Sesti
- Department of Neuroscience and Cell Biology, Robert Wood Johnson Medical School, Rutgers University, West Piscataway, NJ, USA
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Zahra A, Liu R, Wang J, Wu J. Identifying the mechanism of action of the Kv7 channel opener, retigabine in the treatment of epilepsy. Neurol Sci 2023; 44:3819-3825. [PMID: 37442907 DOI: 10.1007/s10072-023-06955-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 07/06/2023] [Indexed: 07/15/2023]
Abstract
Epilepsy is characterized by recurrent epileptic seizures caused by high levels of neuronal excitability in the brain. Voltage-sensitive K+ channels (Kv) of the Kv7 (KCNQ) family encoded by the KCNQ gene are involved in a wide range of cellular processes, i.e., KCNQ2 and KCNQ3 channels mediate M-currents to inhibit neuronal excitability and reduce transmitter release throughout the nervous system. Thus, as a positive allosteric modulator (or opener) of KCNQ channels, retigabine has been the only clinically approved anti-seizure medication that acts on the KCNQ channels. This review discusses the biochemical mechanisms about how retigabine acts on Kv7 channels, significance in neuronal pathophysiology, preclinical efficacy, and clinical stage of development. Additional efforts are being made to emphasize the possible benefits and drawbacks of retigabine compared to currently available medications for treatment-resistant epilepsy.
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Affiliation(s)
- Aqeela Zahra
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China
- Department of Zoology, University of Sialkot, Sialkot, 51310, Pakistan
| | - Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China
- National Clinical Research Center for Neurological Disease, Beijing, 100070, China
| | - Jingjing Wang
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China
| | - Jianping Wu
- Hubei Key Laboratory of Nanomedicine for Neurodegenerative Diseases, School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, 122 Loushi Rd, Wuhan, 430070, China.
- Beijing Tiantan Hospital, Capital Medical University, Beijing, 100070, China.
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing, 100070, China.
- National Clinical Research Center for Neurological Disease, Beijing, 100070, China.
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Sinha AK, Lee C, Holt JC. Elucidating the role of muscarinic acetylcholine receptor (mAChR) signaling in efferent mediated responses of vestibular afferents in mammals. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.31.549902. [PMID: 37577578 PMCID: PMC10418111 DOI: 10.1101/2023.07.31.549902] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
The peripheral vestibular system detects head position and movement through activation of vestibular hair cells (HCs) in vestibular end organs. HCs transmit this information to the CNS by way of primary vestibular afferent neurons. The CNS, in turn, modulates HCs and afferents via the efferent vestibular system (EVS) through activation of cholinergic signaling mechanisms. In mice, we previously demonstrated that activation of muscarinic acetylcholine receptors (mAChRs), during EVS stimulation, gives rise to a slow excitation that takes seconds to peak and tens of seconds to decay back to baseline. This slow excitation is mimicked by muscarine and ablated by the non-selective mAChR blockers scopolamine, atropine, and glycopyrrolate. While five distinct mAChRs (M1-M5) exist, the subtype(s) driving EVS-mediated slow excitation remain unidentified and details on how these mAChRs alter vestibular function is not well understood. The objective of this study is to characterize which mAChR subtypes drive the EVS-mediated slow excitation, and how their activation impacts vestibular physiology and behavior. In C57Bl/6J mice, M3mAChR antagonists were more potent at blocking slow excitation than M1mAChR antagonists, while M2/M4 blockers were ineffective. While unchanged in M2/M4mAChR double KO mice, EVS-mediated slow excitation in M3 mAChR-KO animals were reduced or absent in irregular afferents but appeared unchanged in regular afferents. In agreement, vestibular sensory-evoked potentials (VsEP), known to be predominantly generated from irregular afferents, were significantly less enhanced by mAChR activation in M3mAChR-KO mice compared to controls. Finally, M3mAChR-KO mice display distinct behavioral phenotypes in open field activity, and thermal profiles, and balance beam and forced swim test. M3mAChRs mediate efferent-mediated slow excitation in irregular afferents, while M1mAChRs may drive the same process in regular afferents.
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13
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Manville RW, Hogenkamp D, Abbott GW. Ancient medicinal plant rosemary contains a highly efficacious and isoform-selective KCNQ potassium channel opener. Commun Biol 2023; 6:644. [PMID: 37322081 PMCID: PMC10272180 DOI: 10.1038/s42003-023-05021-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/06/2023] [Indexed: 06/17/2023] Open
Abstract
Voltage-gated potassium (Kv) channels in the KCNQ subfamily serve essential roles in the nervous system, heart, muscle and epithelia. Different heteromeric KCNQ complexes likely serve distinct functions in the brain but heteromer subtype-specific small molecules for research or therapy are lacking. Rosemary (Salvia rosmarinus) is an evergreen plant used medicinally for millennia for neurological and other disorders. Here, we report that rosemary extract is a highly efficacious opener of heteromeric KCNQ3/5 channels, with weak effects on KCNQ2/3. Using functional screening we find that carnosic acid, a phenolic diterpene from rosemary, is a potent, highly efficacious, PIP2 depletion-resistant KCNQ3 opener with lesser effects on KCNQ5 and none on KCNQ1 or KCNQ2. Carnosic acid is also highly selective for KCNQ3/5 over KCNQ2/3 heteromers. Medicinal chemistry, in silico docking, and mutagenesis reveal that carboxylate-guanidinium ionic bonding with an S4-5 linker arginine underlies the KCNQ3 opening proficiency of carnosic acid, the effects of which on KCNQ3/5 suggest unique therapeutic potential and a molecular basis for ancient neurotherapeutic use of rosemary.
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Affiliation(s)
- Rían W Manville
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Derk Hogenkamp
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
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14
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Barro-Soria R. Sensing its own permeant ion: KCNQ1 channel inhibition by external K. J Gen Physiol 2023; 155:e202313337. [PMID: 36961346 PMCID: PMC10072219 DOI: 10.1085/jgp.202313337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/25/2023] Open
Abstract
External potassium inhibits KCNQ1 channel through a mechanism involving increased occupancy of the filter S0 site by K+o.
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Affiliation(s)
- Rene Barro-Soria
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, FL, USA
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15
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Chokvithaya S, Caengprasath N, Buasong A, Jantasuwan S, Santawong K, Leela-adisorn N, Tongkobpetch S, Ittiwut C, Saengow VE, Kamolvisit W, Boonsimma P, Bongsebandhu-phubhakdi S, Shotelersuk V. Nine patients with KCNQ2-related neonatal seizures and functional studies of two missense variants. Sci Rep 2023; 13:3328. [PMID: 36849527 PMCID: PMC9971330 DOI: 10.1038/s41598-023-29924-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 02/13/2023] [Indexed: 03/01/2023] Open
Abstract
Mutations in KCNQ2 encoding for voltage-gated K channel subunits underlying the neuronal M-current have been associated with infantile-onset epileptic disorders. The clinical spectrum ranges from self-limited neonatal seizures to epileptic encephalopathy and delayed development. Mutations in KCNQ2 could be either gain- or loss-of-function which require different therapeutic approaches. To better understand genotype-phenotype correlation, more reports of patients and their mutations with elucidated molecular mechanism are needed. We studied 104 patients with infantile-onset pharmacoresistant epilepsy who underwent exome or genome sequencing. Nine patients with neonatal-onset seizures from unrelated families were found to harbor pathogenic or likely pathogenic variants in the KCNQ2 gene. The p.(N258K) was recently reported, and p. (G279D) has never been previously reported. Functional effect of p.(N258K) and p.(G279D) has never been previously studied. The cellular localization study demonstrated that the surface membrane expression of Kv7.2 carrying either variant was decreased. Whole-cell patch-clamp analyses revealed that both variants significantly impaired Kv7.2 M-current amplitude and density, conductance depolarizing shift in voltage dependence of activation, membrane resistance, and membrane time constant (Tau), indicating a loss-of-function in both the homotetrameric and heterotetrameric with Kv7.3 channels. In addition, both variants exerted dominant-negative effects in heterotetrameric with Kv7.3 channels. This study expands the mutational spectrum of KCNQ2- related epilepsy and their functional consequences provide insights into their pathomechanism.
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Affiliation(s)
- Suphalak Chokvithaya
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand ,grid.415584.90000 0004 0576 1386Department of Clinical Pathology and Medical Technology Laboratory, Queen Sirikit National Institute of Child Health, Ministry of Public Health, Bangkok, Thailand
| | - Natarin Caengprasath
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Aayalida Buasong
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Supavadee Jantasuwan
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Kanokwan Santawong
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Netchanok Leela-adisorn
- grid.7922.e0000 0001 0244 7875Department of Stem Cell and Cell, Therapy Research Unit, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Siraprapa Tongkobpetch
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Chupong Ittiwut
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Vitchayaporn Emarach Saengow
- grid.416297.f0000 0004 0388 8201Department of Pediatrics, Maharat Nakhon Ratchasima Hospital, Nakhon Ratchasima, Thailand
| | - Wuttichart Kamolvisit
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
| | - Ponghatai Boonsimma
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand. .,Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand.
| | - Saknan Bongsebandhu-phubhakdi
- grid.7922.e0000 0001 0244 7875Department of Physiology, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Chula Neuroscience Center, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Vorasuk Shotelersuk
- grid.7922.e0000 0001 0244 7875Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330 Thailand ,grid.419934.20000 0001 1018 2627Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330 Thailand
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16
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Quint WH, Tadema KCD, Kokke NCCJ, Meester-Smoor MA, Miller AC, Willemsen R, Klaver CCW, Iglesias AI. Post-GWAS screening of candidate genes for refractive error in mutant zebrafish models. Sci Rep 2023; 13:2017. [PMID: 36737489 PMCID: PMC9898536 DOI: 10.1038/s41598-023-28944-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/27/2023] [Indexed: 02/05/2023] Open
Abstract
Genome-wide association studies (GWAS) have dissected numerous genetic factors underlying refractive errors (RE) such as myopia. Despite significant insights into understanding the genetic architecture of RE, few studies have validated and explored the functional role of candidate genes within these loci. To functionally follow-up on GWAS and characterize the potential role of candidate genes on the development of RE, we prioritized nine genes (TJP2, PDE11A, SHISA6, LAMA2, LRRC4C, KCNQ5, GNB3, RBFOX1, and GRIA4) based on biological and statistical evidence; and used CRISPR/cas9 to generate knock-out zebrafish mutants. These mutant fish were screened for abnormalities in axial length by spectral-domain optical coherence tomography and refractive status by eccentric photorefraction at the juvenile (2 months) and adult (4 months) developmental stage. We found a significantly increased axial length and myopic shift in refractive status in three of our studied mutants, indicating a potential involvement of the human orthologs (LAMA2, LRRC4C, and KCNQ5) in myopia development. Further, in-situ hybridization studies showed that all three genes are expressed throughout the zebrafish retina. Our zebrafish models provide evidence of a functional role of these three genes in refractive error development and offer opportunities to elucidate pathways driving the retina-to-sclera signaling cascade that leads to myopia.
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Affiliation(s)
- Wim H Quint
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kirke C D Tadema
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Nina C C J Kokke
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Magda A Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adam C Miller
- Institute of Neuroscience, University of Oregon, Eugene, USA
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Adriana I Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
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17
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Dattilo V, Ulivi S, Minelli A, La Bianca M, Giacopuzzi E, Bortolomasi M, Bignotti S, Gennarelli M, Gasparini P, Concas MP. Genome-wide association studies on Northern Italy isolated populations provide further support concerning genetic susceptibility for major depressive disorder. World J Biol Psychiatry 2023; 24:135-148. [PMID: 35615967 DOI: 10.1080/15622975.2022.2082523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVES Major depressive disorder (MDD) is a psychiatric disorder with pathogenesis influenced by both genetic and environmental factors. To date, the molecular-level understanding of its aetiology remains unclear. Thus, we aimed to identify genetic variants and susceptibility genes for MDD with a genome-wide association study (GWAS) approach. METHODS We performed a meta-analysis of GWASs and a gene-based analysis on two Northern Italy isolated populations (cases/controls n = 166/472 and 33/320), followed by replication and polygenic risk score (PRS) analyses in Italian independent samples (cases n = 464, controls n = 339). RESULTS We identified two novel MDD-associated genes, KCNQ5 (lead SNP rs867262, p = 3.82 × 10-9) and CTNNA2 (rs6729523, p = 1.25 × 10-8). The gene-based analysis revealed another six genes (p < 2.703 × 10-6): GRM7, CTNT4, SNRK, SRGAP3, TRAPPC9, and FHIT. No replication of the genome-wide significant SNPs was found in the independent cohort, even if 14 SNPs around CTNNA2 showed association with MDD and related phenotypes at the nominal level of p (<0.05). Furthermore, the PRS model developed in the discovery cohort discriminated cases and controls in the replication cohort. CONCLUSIONS Our work suggests new possible genes associated with MDD, and the PRS analysis confirms the polygenic nature of this disorder. Future studies are required to better understand the role of these findings in MDD.
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Affiliation(s)
- Vincenzo Dattilo
- Genetics Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Sheila Ulivi
- Institute for Maternal and Child Health-IRCCS Burlo Garofolo, Trieste, Italy
| | - Alessandra Minelli
- Genetics Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Martina La Bianca
- Institute for Maternal and Child Health-IRCCS Burlo Garofolo, Trieste, Italy
| | - Edoardo Giacopuzzi
- Wellcome Centre for Human Genetics, Oxford University, Oxford, UK.,NIHR Oxford Biomedical Research Centre, Oxford, UK
| | | | - Stefano Bignotti
- Unit of Psychiatry, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Massimo Gennarelli
- Genetics Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy.,Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Paolo Gasparini
- Institute for Maternal and Child Health-IRCCS Burlo Garofolo, Trieste, Italy.,Department of Medicine, Surgery and Health Science, University of Trieste, Trieste, Italy
| | - Maria Pina Concas
- Institute for Maternal and Child Health-IRCCS Burlo Garofolo, Trieste, Italy
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18
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Potassium channelopathies associated with epilepsy-related syndromes and directions for therapeutic intervention. Biochem Pharmacol 2023; 208:115413. [PMID: 36646291 DOI: 10.1016/j.bcp.2023.115413] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/15/2023]
Abstract
A number of mutations to members of several CNS potassium (K) channel families have been identified which result in rare forms of neonatal onset epilepsy, or syndromes of which one prominent characteristic is a form of epilepsy. Benign Familial Neonatal Convulsions or Seizures (BFNC or BFNS), also referred to as Self-Limited Familial Neonatal Epilepsy (SeLNE), results from mutations in 2 members of the KV7 family (KCNQ) of K channels; while generally self-resolving by about 15 weeks of age, these mutations significantly increase the probability of generalized seizure disorders in the adult, in some cases they result in more severe developmental syndromes. Epilepsy of Infancy with Migrating Focal Seizures (EIMSF), or Migrating Partial Seizures of Infancy (MMPSI), is a rare severe form of epilepsy linked primarily to gain of function mutations in a member of the sodium-dependent K channel family, KCNT1 or SLACK. Finally, KCNMA1 channelopathies, including Liang-Wang syndrome (LIWAS), are rare combinations of neurological symptoms including seizure, movement abnormalities, delayed development and intellectual disabilities, with Liang-Wang syndrome an extremely serious polymalformative syndrome with a number of neurological sequelae including epilepsy. These are caused by mutations in the pore-forming subunit of the large-conductance calcium-activated K channel (BK channel) KCNMA1. The identification of these rare but significant channelopathies has resulted in a resurgence of interest in their treatment by direct pharmacological or genetic modulation. We will briefly review the genetics, biophysics and pharmacology of these K channels, their linkage with the 3 syndromes described above, and efforts to more effectively target these syndromes.
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19
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Paclitaxel Inhibits KCNQ Channels in Primary Sensory Neurons to Initiate the Development of Painful Peripheral Neuropathy. Cells 2022; 11:cells11244067. [PMID: 36552832 PMCID: PMC9776748 DOI: 10.3390/cells11244067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Cancer patients undergoing paclitaxel infusion usually experience peripheral nerve degeneration and serious neuropathic pain termed paclitaxel-induced peripheral neuropathy (PIPN). However, alterations in the dose or treatment schedule for paclitaxel do not eliminate PIPN, and no therapies are available for PIPN, despite numerous studies to uncover the mechanisms underlying the development/maintenance of this condition. Therefore, we aimed to uncover a novel mechanism underlying the pathogenesis of PIPN. Clinical studies suggest that acute over excitation of primary sensory neurons is linked to the pathogenesis of PIPN. We found that paclitaxel-induced acute hyperexcitability of primary sensory neurons results from the paclitaxel-induced inhibition of KCNQ potassium channels (mainly KCNQ2), found abundantly in sensory neurons and axons. We found that repeated application of XE-991, a specific KCNQ channel blocker, induced PIPN-like alterations in rats, including mechanical hypersensitivity and degeneration of peripheral nerves, as detected by both morphological and behavioral assays. In contrast, genetic deletion of KCNQ2 from peripheral sensory neurons in mice significantly attenuated the development of paclitaxel-induced peripheral sensory fiber degeneration and chronic pain. These findings may lead to a better understanding of the causes of PIPN and provide an impetus for developing new classes of KCNQ activators for its therapeutic treatment.
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20
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Emerging mechanisms involving brain Kv7 channel in the pathogenesis of hypertension. Biochem Pharmacol 2022; 206:115318. [PMID: 36283445 DOI: 10.1016/j.bcp.2022.115318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 10/15/2022] [Accepted: 10/17/2022] [Indexed: 12/14/2022]
Abstract
Hypertension is a prevalent health problem inducing many organ damages. The pathogenesis of hypertension involves a complex integration of different organ systems including the brain. The elevated sympathetic nerve activity is closely related to the etiology of hypertension. Ion channels are critical regulators of neuronal excitability. Several mechanisms have been proposed to contribute to hypothalamic-driven elevated sympathetic activity, including altered ion channel function. Recent findings indicate one of the voltage-gated potassium channels, Kv7 channels (M channels), plays a vital role in regulating cardiovascular-related neurons activity, and the expression of Kv7 channels is downregulated in hypertension. This review highlights recent findings that the Kv7 channels in the brain, blood vessels, and kidneys are emerging targets involved in the pathogenesis of hypertension, suggesting new therapeutic targets for treating drug-resistant, neurogenic hypertension.
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21
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Krüger J, Schubert J, Kegele J, Labalme A, Mao M, Heighway J, Seebohm G, Yan P, Koko M, Aslan-Kara K, Caglayan H, Steinhoff BJ, Weber YG, Keo-Kosal P, Berkovic SF, Hildebrand MS, Petrou S, Krause R, May P, Lesca G, Maljevic S, Lerche H. Loss-of-function variants in the KCNQ5 gene are implicated in genetic generalized epilepsies. EBioMedicine 2022; 84:104244. [PMID: 36088682 PMCID: PMC9471468 DOI: 10.1016/j.ebiom.2022.104244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 08/09/2022] [Accepted: 08/16/2022] [Indexed: 11/17/2022] Open
Abstract
Background De novo missense variants in KCNQ5, encoding the voltage-gated K+ channel KV7.5, have been described to cause developmental and epileptic encephalopathy (DEE) or intellectual disability (ID). We set out to identify disease-related KCNQ5 variants in genetic generalized epilepsy (GGE) and their underlying mechanisms. Methods 1292 families with GGE were studied by next-generation sequencing. Whole-cell patch-clamp recordings, biotinylation and phospholipid overlay assays were performed in mammalian cells combined with homology modelling. Findings We identified three deleterious heterozygous missense variants, one truncation and one splice site alteration in five independent families with GGE with predominant absence seizures; two variants were also associated with mild to moderate ID. All missense variants displayed a strongly decreased current density indicating a loss-of-function (LOF). When mutant channels were co-expressed with wild-type (WT) KV7.5 or KV7.5 and KV7.3 channels, three variants also revealed a significant dominant-negative effect on WT channels. Other gating parameters were unchanged. Biotinylation assays indicated a normal surface expression of the variants. The R359C variant altered PI(4,5)P2-interaction. Interpretation Our study identified deleterious KCNQ5 variants in GGE, partially combined with mild to moderate ID. The disease mechanism is a LOF partially with dominant-negative effects through functional deficits. LOF of KV7.5 channels will reduce the M-current, likely resulting in increased excitability of KV7.5-expressing neurons. Further studies on network level are necessary to understand which circuits are affected and how this induces generalized seizures. Funding DFG/FNR Research Unit FOR-2715 (Germany/Luxemburg), BMBF rare disease network Treat-ION (Germany), foundation ‘no epilep’ (Germany).
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22
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Yang ND, Kanyo R, Zhao L, Li J, Kang PW, Dou AK, White KM, Shi J, Nerbonne JM, Kurata HT, Cui J. Electro-mechanical coupling of KCNQ channels is a target of epilepsy-associated mutations and retigabine. SCIENCE ADVANCES 2022; 8:eabo3625. [PMID: 35857840 PMCID: PMC9299555 DOI: 10.1126/sciadv.abo3625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
KCNQ2 and KCNQ3 form the M-channels that are important in regulating neuronal excitability. Inherited mutations that alter voltage-dependent gating of M-channels are associated with neonatal epilepsy. In the homolog KCNQ1 channel, two steps of voltage sensor activation lead to two functionally distinct open states, the intermediate-open (IO) and activated-open (AO), which define the gating, physiological, and pharmacological properties of KCNQ1. However, whether the M-channel shares the same mechanism is unclear. Here, we show that KCNQ2 and KCNQ3 feature only a single conductive AO state but with a conserved mechanism for the electro-mechanical (E-M) coupling between voltage sensor activation and pore opening. We identified some epilepsy-linked mutations in KCNQ2 and KCNQ3 that disrupt E-M coupling. The antiepileptic drug retigabine rescued KCNQ3 currents that were abolished by a mutation disrupting E-M coupling, suggesting that modulating the E-M coupling in KCNQ channels presents a potential strategy for antiepileptic therapy.
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Affiliation(s)
- Nien-Du Yang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Richard Kanyo
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Lu Zhao
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jingru Li
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Po Wei Kang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Alex Kelly Dou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Kelli McFarland White
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
| | - Jeanne M. Nerbonne
- Departments of Developmental Biology and Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Harley T. Kurata
- Department of Pharmacology, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity and Arrhythmia Center, Washington University, St. Louis, MO 63130, USA
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23
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Wei AD, Wakenight P, Zwingman TA, Bard AM, Sahai N, Willemsen MH, Schelhaas HJ, Stegmann APA, Verhoeven JS, de Man SA, Wessels MW, Kleefstra T, Shinde DN, Helbig KL, Basinger A, Wagner VF, Rodriguez-Buritica D, Bryant E, Millichap JJ, Millen KJ, Dobyns WB, Ramirez JM, Kalume FK. Human KCNQ5 de novo mutations underlie epilepsy and intellectual disability. J Neurophysiol 2022; 128:40-61. [PMID: 35583973 PMCID: PMC9236882 DOI: 10.1152/jn.00509.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
We identified six novel de novo human KCNQ5 variants in children with motor/language delay, intellectual disability (ID), and/or epilepsy by whole exome sequencing. These variants, comprising two nonsense and four missense alterations, were functionally characterized by electrophysiology in HEK293/CHO cells, together with four previously reported KCNQ5 missense variants (Lehman A, Thouta S, Mancini GM, Naidu S, van Slegtenhorst M, McWalter K, Person R, Mwenifumbo J, Salvarinova R; CAUSES Study; EPGEN Study; Guella I, McKenzie MB, Datta A, Connolly MB, Kalkhoran SM, Poburko D, Friedman JM, Farrer MJ, Demos M, Desai S, Claydon T. Am J Hum Genet 101: 65-74, 2017). Surprisingly, all eight missense variants resulted in gain of function (GOF) due to hyperpolarized voltage dependence of activation or slowed deactivation kinetics, whereas the two nonsense variants were confirmed to be loss of function (LOF). One severe GOF allele (P369T) was tested and found to extend a dominant GOF effect to heteromeric KCNQ5/3 channels. Clinical presentations were associated with altered KCNQ5 channel gating: milder presentations with LOF or smaller GOF shifts in voltage dependence [change in voltage at half-maximal conduction (ΔV50) = ∼-15 mV] and severe presentations with larger GOF shifts in voltage dependence (ΔV50 = ∼-30 mV). To examine LOF pathogenicity, two Kcnq5 LOF mouse lines were created with CRISPR/Cas9. Both lines exhibited handling- and thermal-induced seizures and abnormal cortical EEGs consistent with epileptiform activity. Our study thus provides evidence for in vivo KCNQ5 LOF pathogenicity and strengthens the contribution of both LOF and GOF mutations to global pediatric neurological impairment, including ID/epilepsy.NEW & NOTEWORTHY Six novel de novo human KCNQ5 variants were identified from children with neurodevelopmental delay, intellectual disability, and/or epilepsy. Expression of these variants along with four previously reported KCNQ5 variants from a similar cohort revealed GOF potassium channels, negatively shifted in V50 of activation and/or delayed deactivation kinetics. GOF is extended to KCNQ5/3 heteromeric channels, making these the predominant channels affected in heterozygous de novo patients. Kcnq5 LOF mice exhibited seizures, consistent with in vivo pathogenicity.
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Affiliation(s)
- Aguan D Wei
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Paul Wakenight
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Theresa A Zwingman
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Angela M Bard
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Nikhil Sahai
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington
| | - Marjolein H Willemsen
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Human Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Helenius J Schelhaas
- Department of Neurology, Academic Centre for Epileptology Kempenhaeghe, Heeze, The Netherlands
| | - Alexander P A Stegmann
- Department of Clinical Genetics, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Judith S Verhoeven
- Department of Neurology, Academic Centre for Epileptology Kempenhaeghe, Heeze, The Netherlands
| | - Stella A de Man
- Department of Pediatrics, Amphia Hospital, Breda, The Netherlands.,Department of Human Genetics, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Marja W Wessels
- Department of Human Genetics, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Tjitske Kleefstra
- Department of Human Genetics and Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - Katherine L Helbig
- Ambry Genetics, Aliso Viejo, California.,Division of Neurology, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania
| | - Alice Basinger
- Medical Genetics, Cook Children's Hospital, Fort Worth, Texas
| | - Victoria F Wagner
- Department of Pediatrics, University of Texas Health Science Center, Houston, Texas
| | | | - Emily Bryant
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - John J Millichap
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois.,Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.,Epilepsy Center, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois
| | - Kathleen J Millen
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.,Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington
| | - William B Dobyns
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.,Department of Pediatrics, University of Washington School of Medicine, Seattle, Washington.,Department of Neurology, University of Washington School of Medicine, Seattle, Washington
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.,Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington
| | - Franck K Kalume
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington.,Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington
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24
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Frampton DJA, Choudhury K, Nikesjö J, Delemotte L, Liin SI. Subtype-specific responses of hKv7.4 and hKv7.5 channels to polyunsaturated fatty acids reveal an unconventional modulatory site and mechanism. eLife 2022; 11:77672. [PMID: 35642964 PMCID: PMC9159753 DOI: 10.7554/elife.77672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 05/11/2022] [Indexed: 11/13/2022] Open
Abstract
The KV7.4 and KV7.5 subtypes of voltage-gated potassium channels play a role in important physiological processes such as sound amplification in the cochlea and adjusting vascular smooth muscle tone. Therefore, the mechanisms that regulate KV7.4 and KV7.5 channel function are of interest. Here, we study the effect of polyunsaturated fatty acids (PUFAs) on human KV7.4 and KV7.5 channels expressed in Xenopus oocytes. We report that PUFAs facilitate activation of hKV7.5 by shifting the V50 of the conductance versus voltage (G(V)) curve toward more negative voltages. This response depends on the head group charge, as an uncharged PUFA analogue has no effect and a positively charged PUFA analogue induces positive V50 shifts. In contrast, PUFAs inhibit activation of hKV7.4 by shifting V50 toward more positive voltages. No effect on V50 of hKV7.4 is observed by an uncharged or a positively charged PUFA analogue. Thus, the hKV7.5 channel's response to PUFAs is analogous to the one previously observed in hKV7.1-7.3 channels, whereas the hKV7.4 channel response is opposite, revealing subtype-specific responses to PUFAs. We identify a unique inner PUFA interaction site in the voltage-sensing domain of hKV7.4 underlying the PUFA response, revealing an unconventional mechanism of modulation of hKV7.4 by PUFAs.
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Affiliation(s)
- Damon J A Frampton
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Koushik Choudhury
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Johan Nikesjö
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lucie Delemotte
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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25
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Edmond MA, Hinojo-Perez A, Wu X, Perez Rodriguez ME, Barro-Soria R. Distinctive mechanisms of epilepsy-causing mutants discovered by measuring S4 movement in KCNQ2 channels. eLife 2022; 11:77030. [PMID: 35642783 PMCID: PMC9197397 DOI: 10.7554/elife.77030] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 05/31/2022] [Indexed: 01/10/2023] Open
Abstract
Neuronal KCNQ channels mediate the M-current, a key regulator of membrane excitability in the central and peripheral nervous systems. Mutations in KCNQ2 channels cause severe neurodevelopmental disorders, including epileptic encephalopathies. However, the impact that different mutations have on channel function remains poorly defined, largely because of our limited understanding of the voltage-sensing mechanisms that trigger channel gating. Here, we define the parameters of voltage sensor movements in wt-KCNQ2 and channels bearing epilepsy-associated mutations using cysteine accessibility and voltage clamp fluorometry (VCF). Cysteine modification reveals that a stretch of eight to nine amino acids in the S4 becomes exposed upon voltage sensing domain activation of KCNQ2 channels. VCF shows that the voltage dependence and the time course of S4 movement and channel opening/closing closely correlate. VCF reveals different mechanisms by which different epilepsy-associated mutations affect KCNQ2 channel voltage-dependent gating. This study provides insight into KCNQ2 channel function, which will aid in uncovering the mechanisms underlying channelopathies.
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Affiliation(s)
- Michaela A Edmond
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, United States
| | - Andy Hinojo-Perez
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, United States
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Marta E Perez Rodriguez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Rene Barro-Soria
- Department of Medicine, Miller School of Medicine, University of Miami, Miami, United States
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26
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Gain of function due to increased opening probability by two KCNQ5 pore variants causing developmental and epileptic encephalopathy. Proc Natl Acad Sci U S A 2022; 119:e2116887119. [PMID: 35377796 PMCID: PMC9169635 DOI: 10.1073/pnas.2116887119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Variants in genes encoding neuronally expressed potassium channel subunits are frequent causes of developmental and epileptic encephalopathies (DEEs). Characterization of their functional consequences is critical to confirm diagnosis, assess prognosis, and implement personalized treatments. In the present work, we describe two patients carrying variants in KCNQ5, a gene very recently and rarely found involved in DEEs, and reveal that they both cause remarkable gain-of-function consequences on channel activity. A PIP2-independent increase in open probability, without effects on membrane abundance or single-channel conductance, was responsible for the observed mutation-induced functional changes, thus revealing a pathomolecular disease mechanism for DEEs. Developmental and epileptic encephalopathies (DEEs) are neurodevelopmental diseases characterized by refractory epilepsy, distinct electroencephalographic and neuroradiological features, and various degrees of developmental delay. Mutations in KCNQ2, KCNQ3, and, more rarely, KCNQ5 genes encoding voltage-gated potassium channel subunits variably contributing to excitability control of specific neuronal populations at distinct developmental stages have been associated to DEEs. In the present work, the clinical features of two DEE patients carrying de novo KCNQ5 variants affecting the same residue in the pore region of the Kv7.5 subunit (G347S/A) are described. The in vitro functional properties of channels incorporating these variants were investigated with electrophysiological and biochemical techniques to highlight pathophysiological disease mechanisms. Currents carried by Kv7.5 G347 S/A channels displayed: 1) large (>10 times) increases in maximal current density, 2) the occurrence of a voltage-independent component, 3) slower deactivation kinetics, and 4) hyperpolarization shift in activation. All these functional features are consistent with a gain-of-function (GoF) pathogenetic mechanism. Similar functional changes were also observed when the same variants were introduced at the corresponding position in Kv7.2 subunits. Nonstationary noise analysis revealed that GoF effects observed for both Kv7.2 and Kv7.5 variants were mainly attributable to an increase in single-channel open probability, without changes in membrane abundance or single-channel conductance. The mutation-induced increase in channel opening probability was insensitive to manipulation of membrane levels of the critical Kv7 channel regulator PIP2. These results reveal a pathophysiological mechanism for KCNQ5-related DEEs, which might be exploited to implement personalized treatments.
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27
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Biba N, Becq H, Pallesi-Pocachard E, Sarno S, Granjeaud S, Montheil A, Kurz M, Villard L, Milh M, Santini PPL, Aniksztejn L. Time-limited alterations in cortical activity of a knock-in mice model of KCNQ2-related developmental and epileptic encephalopathy. J Physiol 2022; 600:2429-2460. [PMID: 35389519 DOI: 10.1113/jp282536] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 03/10/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The electrophysiological impact of the pathogenic c.821C>T mutation of the KCNQ2 gene (p.T274M variant in Kv7.2 subunit) related to Developmental and Epileptic Encephalopathy has been analyzed both in vivo and ex-vivo in layers II/III and V of motor cortical slice from a knock-in mice model during development at neonatal, post-weaning and juvenile stages. M current density and conductance are decreased and excitability of layers II/III pyramidal cells is increased in slices from neonatal and post-weaning KI mice but not from juvenile KI mice. M current and excitability of layer V pyramidal cells are impacted in KI mice only at post-weaning stage. Spontaneous GABAergic network-driven events are recorded until post-weaning stage and their frequency are increased in layers II/III of the KI mice. KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. ABSTRACT De novo missense variants in the KCNQ2 gene encoding the Kv7.2 subunit of the voltage-gated potassium Kv7/M channels are the main cause of Developmental and Epileptic Encephalopathy (DEE) with neonatal onset. While seizures usually resolve during development, cognitive/motor deficits persist. To better understand the cellular mechanisms underlying network dysfunction and their progression over time, we investigated in vivo, using local field potential recordings of freely moving animals, and ex-vivo in layers II/III and V of motor cortical slices, using patch-clamp recordings, the electrophysiological properties of pyramidal cells from a heterozygous knock-in (KI) mouse model carrying the Kv7.2 p.T274M pathogenic variant during neonatal, post-weaning and juvenile developmental stages. We found that KI mice displayed spontaneous seizures preferentially at post-weaning rather than at juvenile stages. At the cellular level, the variant led to a reduction in M current density/conductance and to neuronal hyperexcitability. These alterations were observed during the neonatal period in pyramidal cells of layers II /III and during post-weaning stage in pyramidal cells of layer V. Moreover, there was an increase in the frequency of spontaneous network driven events mediated by GABA receptors suggesting that the excitability of interneurons was also increased. However, all these alterations were no more observed in layers II/III and V of juvenile mice. Thus, our data indicate that the action of the variant is developmentally regulated. This raises the possibility that the age related seizure remission observed in KCNQ2-related DEE patient results from a time limited alteration of Kv7 channels activity and neuronal excitability. Abstract figure legend Knock-in mice harboring the heterozygous pathogenic p.T274M variant in the Kv7.2 subunit (c.821C>T mutation of the KCNQ2 gene) related to Developmental and Epileptic Encephalopathy displayed epileptic seizures preferentially at post-weaning rather than at juvenile developmental stages. At cellular level, in motor cortical slices the variant led to a reduction in M current density, to a hyperexcitability of pyramidal cells and to an increase in the frequency of spontaneous network driven events mediated by GABA receptors. All these alterations are time limited and are observed in pyramidal cells of neonatal mice until post-weaning but not of juvenile mice in which the pyramidal cells have electrophysiological properties similar to those of wild-type mice. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Najoua Biba
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Hélène Becq
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Emilie Pallesi-Pocachard
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Stefania Sarno
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Samuel Granjeaud
- Centre de Recherche en Cancérologie de Marseille, INSERM, U1068, Institut Paoli Calmettes, CNRS, UMR7258, Aix-Marseille University UM 105, Marseille, France
| | - Aurélie Montheil
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Marie Kurz
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
| | - Laurent Villard
- Aix-Marseille University, INSERM, MMG, Marseille, France.,Department of Medical Genetics, La Timone Childrens's Hospital, Marseille, France
| | - Mathieu Milh
- Aix-Marseille University, INSERM, MMG, Marseille, France.,Department of Pediatric Neurology, La Timone Children's Hospital, Marseille, France
| | | | - Laurent Aniksztejn
- INSERM, INMED (U1249), Aix-Marseille University, Turing centre for living system, Marseille, France
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28
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Abstract
KCNQ2 and KCNQ3 channels are associated with multiple neurodevelopmental disorders and are also therapeutic targets for neurological and neuropsychiatric diseases. For more than two decades, it has been thought that most KCNQ channels in the brain are either KCNQ2/3 or KCNQ3/5 heteromers. Here, we investigated the potential heteromeric compositions of KCNQ2-containing channels. We applied split-intein protein trans-splicing to form KCNQ2/5 tandems and coexpressed these with and without KCNQ3. Unexpectedly, we found that KCNQ2/5 tandems form functional channels independent of KCNQ3 in heterologous cells. Using mass spectrometry, we went on to demonstrate that KCNQ2 associates with KCNQ5 in native channels in the brain, even in the absence of KCNQ3. Additionally, our functional heterologous expression data are consistent with the formation of KCNQ2/3/5 heteromers. Thus, the composition of KCNQ channels is more diverse than has been previously recognized, necessitating a re-examination of the genotype/phenotype relationship of KCNQ2 pathogenic variants.
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29
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Ye H, Liu ZX, He YJ, Wang X. Effects of M currents on the persistent activity of pyramidal neurons in mouse primary auditory cortex. J Neurophysiol 2022; 127:1269-1278. [PMID: 35294269 DOI: 10.1152/jn.00332.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuronal persistent activity (PA) is a common phenomenon observed in many types of neurons. PA can be induced in neurons in the mouse auditory nucleus by activating cholinergic receptors with carbachol (CCh), a dual muscarinic and nicotinic receptor agonist. PA is presumed to be associated with learning-related auditory plasticity at the cellular level. However, the mechanism is not clearly understood. Many studies have reported that muscarinic cholinergic receptor agonists inhibit muscarinic-sensitive potassium channels (M channels). Potassium influx through M channels produces potassium currents, called M currents, which play an essential role in regulating neural excitability and synaptic plasticity. Further study is needed to determine whether M currents affect the PA of auditory central neurons and provide additional analysis of the variations in electrophysiological properties. We used in vitro whole-cell patch-clamp recordings in isolated mouse brain slices to investigate the effects of M currents on the PA in pyramidal neurons in layer V of the primary auditory cortex (AI-L5). We found that blocking M currents with XE991 depolarized the AI-L5 pyramidal neurons, which significantly increased the input resistance. The active threshold and threshold intensity were significantly reduced, indicating that the intrinsic excitability was enhanced. Our results also showed that blocking M currents with XE991 switched the neuronal firing patterns in the AI-L5 pyramidal neurons from regular-spiking to intrinsic-bursting. Blocking M currents facilitated PA by increasing the plateau potential and enhancing intrinsic excitability. Our results suggested that blocking M currents might facilitate the PA in AI-L5 pyramidal neurons, which underlies auditory plasticity.
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Affiliation(s)
- Huan Ye
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Zhen-Xu Liu
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Ya-Jie He
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Xin Wang
- Hubei Key Lab of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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30
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Kv7 Channels in Cyclic-Nucleotide Dependent Relaxation of Rat Intra-Pulmonary Artery. Biomolecules 2022; 12:biom12030429. [PMID: 35327621 PMCID: PMC8946781 DOI: 10.3390/biom12030429] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 02/24/2022] [Accepted: 02/25/2022] [Indexed: 12/22/2022] Open
Abstract
Pulmonary hypertension is treated with drugs that stimulate cGMP or cAMP signalling. Both nucleotides can activate Kv7 channels, leading to smooth muscle hyperpolarisation, reduced Ca2+ influx and relaxation. Kv7 activation by cGMP contributes to the pulmonary vasodilator action of nitric oxide, but its contribution when dilation is evoked by the atrial natriuretic peptide (ANP) sensitive guanylate cyclase, or cAMP, is unknown. Small vessel myography was used to investigate the ability of Kv7 channel blockers to interfere with pulmonary artery relaxation when cyclic nucleotide pathways were stimulated in different ways. The pan-Kv7 blockers, linopirdine and XE991, caused substantial inhibition of relaxation evoked by NO donors and ANP, as well as endothelium-dependent dilators, the guanylate cyclase stimulator, riociguat, and the phosphodiesterase-5 inhibitor, sildenafil. Maximum relaxation was reduced without a change in sensitivity. The blockers had relatively little effect on cAMP-mediated relaxation evoked by forskolin, isoprenaline or treprostinil. The Kv7.1-selective blocker, HMR1556, had no effect on cGMP or cAMP-dependent relaxation. Western blot analysis demonstrated the presence of Kv7.1 and Kv7.4 proteins, while selective activators of Kv7.1 and Kv7.4 homomeric channels, but not Kv7.5, caused pulmonary artery relaxation. It is concluded that Kv7.4 channels contribute to endothelium-dependent dilation and the effects of drugs that act by stimulating cGMP, but not cAMP, signalling.
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31
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Sheng ZF, Zhang H, Zheng P, Chen S, Gu Z, Zhou JJ, Phaup JG, Chang HM, Yeh ETH, Pan HL, Li DP. Impaired Kv7 channel activity in the central amygdala contributes to elevated sympathetic outflow in hypertension. Cardiovasc Res 2022; 118:585-596. [PMID: 33512443 PMCID: PMC8803073 DOI: 10.1093/cvr/cvab031] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 11/11/2020] [Accepted: 01/25/2021] [Indexed: 11/13/2022] Open
Abstract
AIMS Elevated sympathetic outflow is associated with primary hypertension. However, the mechanisms involved in heightened sympathetic outflow in hypertension are unclear. The central amygdala (CeA) regulates autonomic components of emotions through projections to the brainstem. The neuronal Kv7 channel is a non-inactivating voltage-dependent K+ channel encoded by KCNQ2/3 genes involved in stabilizing the neuronal membrane potential and regulating neuronal excitability. In this study, we investigated if altered Kv7 channel activity in the CeA contributes to heightened sympathetic outflow in hypertension. METHODS AND RESULTS The mRNA and protein expression levels of Kv7.2/Kv7.3 in the CeA were significantly reduced in spontaneously hypertensive rats (SHRs) compared with Wistar-Kyoto (WKY) rats. Lowering blood pressure with coeliac ganglionectomy in SHRs did not alter Kv7.2 and Kv7.3 channel expression levels in the CeA. Fluospheres were injected into the rostral ventrolateral medulla (RVLM) to retrogradely label CeA neurons projecting to the RVLM (CeA-RVLM neurons). Kv7 channel currents recorded from CeA-RVLM neurons in brain slices were much smaller in SHRs than in WKY rats. Furthermore, the basal firing activity of CeA-RVLM neurons was significantly greater in SHRs than in WKY rats. Bath application of specific Kv7 channel blocker 10, 10-bis (4-pyridinylmethyl)-9(10H)-anthracnose (XE-991) increased the excitability of CeA-RVLM neurons in WKY rats, but not in SHRs. Microinjection of XE-991 into the CeA increased arterial blood pressure (ABP) and renal sympathetic nerve activity (RSNA), while microinjection of Kv7 channel opener QO-58 decreased ABP and RSNA, in anaesthetized WKY rats but not SHRs. CONCLUSIONS Our findings suggest that diminished Kv7 channel activity in the CeA contributes to elevated sympathetic outflow in primary hypertension. This novel information provides new mechanistic insight into the pathogenesis of neurogenic hypertension.
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Affiliation(s)
- Zhao-Fu Sheng
- Center for Precision Medicine, Department of Medicine, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
| | - Hua Zhang
- Center for Precision Medicine, Department of Medicine, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
| | - PeiRu Zheng
- Center for Precision Medicine, Department of Medicine, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
| | - Shanyan Chen
- Department of Pathology and Anatomical Sciences, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
| | - Zezong Gu
- Department of Pathology and Anatomical Sciences, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
| | - Jing-Jing Zhou
- Department of Anesthesiology and Perioperative Medicine, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
| | - Jeffery G Phaup
- Center for Precision Medicine, Department of Medicine, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
| | - Hui-Ming Chang
- Departments of Pharmacology and Toxicology and Internal Medicine, The University of Arkansas for Medical Sciences, 4301 West Markham St., Little Rock, AR 72205, USA
| | - Edward T H Yeh
- Departments of Pharmacology and Toxicology and Internal Medicine, The University of Arkansas for Medical Sciences, 4301 West Markham St., Little Rock, AR 72205, USA
| | - Hui-Lin Pan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA
| | - De-Pei Li
- Center for Precision Medicine, Department of Medicine, School of Medicine, University of Missouri, 1 Hospital Drive, Columbia, MO 65212, USA
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32
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Fan XZ, Wang YY, Cui ZY, Cheng ZH, Zhang HL, Gamper N, Zhang F, Han M. Kv7.4 channel is a key regulator of vascular inflammation and remodeling in neointimal hyperplasia and abdominal aortic aneurysms. Free Radic Biol Med 2022; 178:111-124. [PMID: 34863875 DOI: 10.1016/j.freeradbiomed.2021.11.041] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/08/2021] [Accepted: 11/30/2021] [Indexed: 12/16/2022]
Abstract
Inflammation has recently emerged as an important contributor for cardiovascular disease development and participates pivotally in the development of neointimal hyperplasia and abdominal aortic aneurysms (AAA) formation. Kv7.4/KCNQ4, a K+ channel, is one of the important regulators of vascular function but its role in vascular inflammation is unexplored. Here, we showed that the expression of Kv7.4 channel was elevated in the neointima and AAA tissues from mice and humans. Genetic deletion or pharmacological inhibition of Kv7.4 channel in mice alleviated neointimal hyperplasia and AAA formation via downregulation of a set of vascular inflammation-related genes, matrix metalloproteinases (MMP) 2/9, and intercellular adhesion molecule (ICAM-1). Furthermore, genetic deletion or inhibition of Kv7.4 channel suppressed the activation of tumor necrosis factor receptor 1 (TNFR1)-nuclear factor (NF)-κB signaling pathway via blockade of interaction between TNFR1 and TNFR1-associated death domain protein (TRADD) in vascular smooth muscle cells (VSMCs). Knockdown of Kv7.4 in vivo identified VSMC-expressed Kv7.4 as a major factor in vascular inflammation. Collectively, our findings suggest that Kv7.4 channel aggravates vascular inflammatory response, which promotes the neointimal hyperplasia and AAA formation. Inhibition of Kv7.4 channel may be a novel therapeutic strategy for vascular inflammatory diseases.
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Affiliation(s)
- Xi-Zhenzi Fan
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Ying-Ying Wang
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Zi-Yang Cui
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Zi-Hao Cheng
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Hai-Lin Zhang
- Department of Pharmacology, Key Laboratory of Neural and Vascular Biology, Ministry of Education, PR China; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, 050017, PR China
| | - Nikita Gamper
- Department of Pharmacology, Key Laboratory of Neural and Vascular Biology, Ministry of Education, PR China; Key Laboratory of New Drug Pharmacology and Toxicology, Hebei Medical University, Shijiazhuang, 050017, PR China; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Fan Zhang
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, PR China.
| | - Mei Han
- Department of Biochemistry and Molecular Biology, College of Basic Medicine, Key Laboratory of Medical Biotechnology of Hebei Province, Key Laboratory of Neural and Vascular Biology of Ministry of Education, Hebei Medical University, Shijiazhuang, 050017, PR China.
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Yang Q, Tan QQ, Lan CJ, Lv BZ, Zhou GM, Zhong WQ, Gu ZM, Mao YM, Liao X. The Changes of KCNQ5 Expression and Potassium Microenvironment in the Retina of Myopic Guinea Pigs. Front Physiol 2021; 12:790580. [PMID: 35002772 PMCID: PMC8733613 DOI: 10.3389/fphys.2021.790580] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
KCNQ5 is suggestively associated with myopia, but its specific role in the myopic process has not been studied further. The aim of this study was to investigate the expression of potassium channel gene KCNQ5 and the changes of K+ microenvironment within the retina of form deprivation myopia (FDM) guinea pigs. A total of 60 guinea pigs were randomly divided into the normal control (NC) group, the self-control (SC) group, and the form-deprivation (FD) group for different treatments. Molecular assays and immunohistochemistry (IHC) were conducted to measure the expression and distribution of KCNQ5-related gene and protein in the retina. We determined the K+ concentration in the retina. In addition, the possible effects of form deprivation on potassium ionic currents and the pharmacological sensitivity of KCNQ5 activator Retigabine and inhibitor XE991 to the M-current in RPE cells were investigated using the patch-clamp technique. As a result, FD eyes exhibited more myopic refraction and longer AL. The mRNA and protein levels of KCNQ5 significantly decreased in the FD eyes, but the K+ concentration increased. In addition, the M-type K+ current [IK(M)] density decreased in FD RPE cells, and were activated or inhibited in a concentration-dependent manner due to the addition of Retigabine or XE991. Overall, KCNQ5 was significantly downregulated in the retina of FD guinea pigs, which may be associated with the increasing K+ concentration, decreasing IK(M) density, and elongating ocular axis. It suggested that KCNQ5 may play a role in the process of myopia, and the intervention of potassium channels may contribute to the prevention and control of myopia.
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Affiliation(s)
- Qin Yang
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Qing Qing Tan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Chang Jun Lan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Bo Zhen Lv
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Gui Mei Zhou
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Wei Qi Zhong
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Zhi Ming Gu
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Yu Mei Mao
- The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xuan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
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Martin-Batista E, Manville RW, Rivero-Pérez B, Bartolomé-Martín D, Alvarez de la Rosa D, Abbott GW, Giraldez T. Activation of SGK1.1 Upregulates the M-current in the Presence of Epilepsy Mutations. Front Mol Neurosci 2021; 14:798261. [PMID: 34899186 PMCID: PMC8662703 DOI: 10.3389/fnmol.2021.798261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 11/01/2021] [Indexed: 11/13/2022] Open
Abstract
In the central nervous system, the M-current plays a critical role in regulating subthreshold electrical excitability of neurons, determining their firing properties and responsiveness to synaptic input. The M-channel is mainly formed by subunits Kv7.2 and Kv7.3 that co-assemble to form a heterotetrametric channel. Mutations in Kv7.2 and Kv7.3 are associated with hyperexcitability phenotypes including benign familial neonatal epilepsy (BFNE) and neonatal epileptic encephalopathy (NEE). SGK1.1, the neuronal isoform of the serum and glucocorticoids-regulated kinase 1 (SGK1), increases M-current density in neurons, leading to reduced excitability and protection against seizures. Herein, using two-electrode voltage clamp on Xenopus laevis oocytes, we demonstrate that SGK1.1 selectively activates heteromeric Kv7 subunit combinations underlying the M-current. Importantly, activated SGK1.1 increases M-channel activity in the presence of two different epilepsy mutations found in Kv7.2, R207W and A306T. In addition, proximity ligation assays in the N2a cell line allowed us to address the effect of these mutations on Kv7-SGK1.1-Nedd4 molecular associations, a proposed pathway underlying augmentation of M-channel activity by SGK1.1.
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Affiliation(s)
- Elva Martin-Batista
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - Rían W Manville
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Belinda Rivero-Pérez
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - David Bartolomé-Martín
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - Diego Alvarez de la Rosa
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
| | - Teresa Giraldez
- Departamento de Ciencias Medicas Basicas and Instituto de Tecnologias Biomedicas, Universidad de La Laguna, San Cristóbal de La Laguna, Spain
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Trofimenko E, Grasso G, Heulot M, Chevalier N, Deriu MA, Dubuis G, Arribat Y, Serulla M, Michel S, Vantomme G, Ory F, Dam LC, Puyal J, Amati F, Lüthi A, Danani A, Widmann C. Genetic, cellular, and structural characterization of the membrane potential-dependent cell-penetrating peptide translocation pore. eLife 2021; 10:69832. [PMID: 34713805 PMCID: PMC8639150 DOI: 10.7554/elife.69832] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 10/28/2021] [Indexed: 12/11/2022] Open
Abstract
Cell-penetrating peptides (CPPs) allow intracellular delivery of bioactive cargo molecules. The mechanisms allowing CPPs to enter cells are ill-defined. Using a CRISPR/Cas9-based screening, we discovered that KCNQ5, KCNN4, and KCNK5 potassium channels positively modulate cationic CPP direct translocation into cells by decreasing the transmembrane potential (Vm). These findings provide the first unbiased genetic validation of the role of Vm in CPP translocation in cells. In silico modeling and live cell experiments indicate that CPPs, by bringing positive charges on the outer surface of the plasma membrane, decrease the Vm to very low values (–150 mV or less), a situation we have coined megapolarization that then triggers formation of water pores used by CPPs to enter cells. Megapolarization lowers the free energy barrier associated with CPP membrane translocation. Using dyes of varying dimensions in CPP co-entry experiments, the diameter of the water pores in living cells was estimated to be 2 (–5) nm, in accordance with the structural characteristics of the pores predicted by in silico modeling. Pharmacological manipulation to lower transmembrane potential boosted CPP cellular internalization in zebrafish and mouse models. Besides identifying the first proteins that regulate CPP translocation, this work characterized key mechanistic steps used by CPPs to cross cellular membranes. This opens the ground for strategies aimed at improving the ability of cells to capture CPP-linked cargos in vitro and in vivo. Before a drug can have its desired effect, it must reach its target tissue or organ, and enter its cells. This is not easy because cells are surrounded by the plasma membrane, a fat-based barrier that separates the cell from its external environment. The plasma membrane contains proteins that act as channels, shuttling specific molecules in and out of the cell, and it also holds charge, with its inside surface being more negatively charged than its outside surface. Cell-penetrating peptides are short sequences of amino acids (the building blocks that form proteins) that carry positive charges. These positive charges allow them to cross the membrane easily, but it is not well understood how. To find out how cell-penetrating peptides cross the membrane, Trofimenko et al. attached them to dyes of different sizes. This revealed that the cell-penetrating peptides enter the cell through temporary holes called water pores, which measure about two nanometres across. The water pores form when the membrane becomes ‘megapolarized’, this is, when the difference in charge between the inside and the outside of the membrane becomes greater than normal. This can happen when the negative charge on the inside surface or the positive charge on the outer surface of the membrane increase. Megapolarization depends on potassium channels, which transport positive potassium ions outside the cell, making the outside of the membrane positive. When cell-penetrating peptides arrive at the outer surface of the cell near potassium channels, they make it even more positive. This increases the charge difference between the inside and the outside of the cell, allowing water pores to form. Once the peptides pass through the pores, the charge difference between the inside and the outside of the cell membrane dissipates, and the pores collapse. Drug developers are experimenting with attaching cell-penetrating peptides to drugs to help them get inside their target cells. Currently there are several experimental medications of this kind in clinical trials. Understanding how these peptides gain entry, and what size of molecule they could carry with them, provides solid ground for further drug development.
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Affiliation(s)
- Evgeniya Trofimenko
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Gianvito Grasso
- Dalle Molle Institute for Artificial Intelligence Research, Università della Svizzera italiana, Scuola Universitaria Professionale della Svizzera Italiana, Lugano, Switzerland
| | - Mathieu Heulot
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nadja Chevalier
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Marco A Deriu
- PolitoBIOMed Lab Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Torino, Italy
| | - Gilles Dubuis
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Yoan Arribat
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Marc Serulla
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Sebastien Michel
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Gil Vantomme
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Florine Ory
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Linh Chi Dam
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,CURML (University Center of Legal Medicine), Lausanne University Hospital, Lausanne, Switzerland
| | - Francesca Amati
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Andrea Danani
- Dalle Molle Institute for Artificial Intelligence Research, Università della Svizzera italiana, Scuola Universitaria Professionale della Svizzera Italiana, Lugano, Switzerland
| | - Christian Widmann
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland
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Stincic TL, Bosch MA, Hunker AC, Juarez B, Connors AM, Zweifel LS, Rønnekleiv OK, Kelly MJ. CRISPR knockdown of Kcnq3 attenuates the M-current and increases excitability of NPY/AgRP neurons to alter energy balance. Mol Metab 2021; 49:101218. [PMID: 33766732 PMCID: PMC8093934 DOI: 10.1016/j.molmet.2021.101218] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/12/2021] [Accepted: 03/18/2021] [Indexed: 02/06/2023] Open
Abstract
OBJECTIVE Arcuate nucleus neuropeptide Y/agouti-related peptide (NPY/AgRP) neurons drive ingestive behavior. The M-current, a subthreshold non-inactivating potassium current, plays a critical role in regulating NPY/AgRP neuronal excitability. Fasting decreases while 17β-estradiol increases the M-current by regulating the mRNA expression of Kcnq2, 3, and 5 (Kv7.2, 3, and 5) channel subunits. Incorporating KCNQ3 into heteromeric channels has been considered essential to generate a robust M-current. Therefore, we investigated the behavioral and physiological effects of selective Kcnq3 deletion from NPY/AgRP neurons. METHODS We used a single adeno-associated viral vector containing a recombinase-dependent Staphylococcus aureus Cas9 with a single-guide RNA to selectively delete Kcnq3 in NPY/AgRP neurons. Single-cell quantitative measurements of mRNA expression and whole-cell patch clamp experiments were conducted to validate the selective knockdown. Body weight, food intake, and locomotor activity were measured in male mice to assess disruptions in energy balance. RESULTS The virus reduced the expression of Kcnq3 mRNA without affecting Kcnq2 or Kcnq5. The M-current was attenuated, causing NPY/AgRP neurons to be more depolarized, exhibit a higher input resistance, and require less depolarizing current to fire action potentials, indicative of increased excitability. Although the resulting decrease in the M-current did not overtly alter ingestive behavior, it significantly reduced the locomotor activity as measured by open-field testing. Control mice on a high-fat diet exhibited an enhanced M-current and increased Kcnq2 and Kcnq3 expression, but the M-current remained significantly attenuated in KCNQ3 knockdown animals. CONCLUSIONS The M-current plays a critical role in modulating the intrinsic excitability of NPY/AgRP neurons that is essential for maintaining energy homeostasis.
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Affiliation(s)
- Todd L Stincic
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA.
| | - Martha A Bosch
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Avery C Hunker
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Barbara Juarez
- Department of Pharmacology, University of Washington, Seattle, WA, 98195, USA
| | - Ashley M Connors
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA
| | - Larry S Zweifel
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA, 98195, USA; Department of Pharmacology, University of Washington, Seattle, WA, 98195, USA
| | - Oline K Rønnekleiv
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, 97006, USA
| | - Martin J Kelly
- Department of Chemical Physiology and Biochemistry, Oregon Health and Science University, Portland, OR, 97239, USA; Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR, 97006, USA.
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Naffaa MM, Al-Ewaidat OA. Ligand modulation of KCNQ-encoded (K V7) potassium channels in the heart and nervous system. Eur J Pharmacol 2021; 906:174278. [PMID: 34174270 DOI: 10.1016/j.ejphar.2021.174278] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 06/06/2021] [Accepted: 06/18/2021] [Indexed: 10/21/2022]
Abstract
KCNQ-encoded (KV7) potassium channels are diversely distributed in the human tissues, associated with many physiological processes and pathophysiological conditions. These channels are increasingly used as drug targets for treating diseases. More selective and potent molecules on various types of the KV7 channels are desirable for appropriate therapies. The recent knowledge of the structure and function of human KCNQ-encoded channels makes it more feasible to achieve these goals. This review discusses the role and mechanism of action of many molecules in modulating the function of the KCNQ-encoded potassium channels in the heart and nervous system. The effects of these compounds on KV7 channels help to understand their involvement in many diseases, and to search for more selective and potent ligands to be used in the treatment of many disorders such as various types of cardiac arrhythmias, epilepsy, and pain.
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Affiliation(s)
- Moawiah M Naffaa
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, 27710, USA; Department of Psychology and Neuroscience, Duke University, Durham, NC 27708, USA.
| | - Ola A Al-Ewaidat
- Faculty of Medicine, The University of Jordan, Amman, 11942, Jordan
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Park S, Flüthmann P, Wolany C, Goedecke L, Spenner HM, Budde T, Pape HC, Jüngling K. Neuropeptide S Receptor Stimulation Excites Principal Neurons in Murine Basolateral Amygdala through a Calcium-Dependent Decrease in Membrane Potassium Conductance. Pharmaceuticals (Basel) 2021; 14:ph14060519. [PMID: 34072275 PMCID: PMC8230190 DOI: 10.3390/ph14060519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/18/2021] [Accepted: 05/18/2021] [Indexed: 02/08/2023] Open
Abstract
Background: The neuropeptide S system, consisting of the 20 amino acid neuropeptide NPS and its G-protein-coupled receptor (GPCR) neuropeptide S receptor 1 (NPSR1), has been studied intensively in rodents. Although there is a lot of data retrieved from behavioral studies using pharmacology or genetic interventions, little is known about intracellular signaling cascades in neurons endogenously expressing the NPSR1. Methods: To elucidate possible G-protein-dependent signaling and effector systems, we performed whole-cell patch-clamp recordings on principal neurons of the anterior basolateral amygdala of mice. We used pharmacological interventions to characterize the NPSR1-mediated current induced by NPS application. Results: Application of NPS reliably evokes inward-directed currents in amygdalar neurons recorded in brain slice preparations of male and female mice. The NPSR1-mediated current had a reversal potential near the potassium reversal potential (EK) and was accompanied by an increase in membrane input resistance. GDP-β-S and BAPTA, but neither adenylyl cyclase inhibition nor 8-Br-cAMP, abolished the current. Intracellular tetraethylammonium or 4-aminopyridine reduced the NPS-evoked current. Conclusion: NPSR1 activation in amygdalar neurons inhibits voltage-gated potassium (K+) channels, most likely members of the delayed rectifier family. Intracellularly, Gαq signaling and calcium ions seem to be mandatory for the observed current and increased neuronal excitability.
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39
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Wright AB, Sukhanova KY, Elmslie KS. K V7 channels are potential regulators of the exercise pressor reflex. J Neurophysiol 2021; 126:1-10. [PMID: 34038189 DOI: 10.1152/jn.00700.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The exercise pressor reflex (EPR) originates in skeletal muscle and is activated by exercise-induced signals to increase arterial blood pressure and cardiac output. Muscle ischemia can elicit the EPR, which can be inappropriately activated in patients with peripheral vascular disease or heart failure to increase the incidence of myocardial infarction. We seek to better understand the receptor/channels that control excitability of group III and group IV muscle afferent fibers that give rise to the EPR. Bradykinin (BK) is released within contracting muscle and can evoke the EPR. However, the mechanism is incompletely understood. KV7 channels strongly regulate neuronal excitability and are inhibited by BK. We have identified KV7 currents in muscle afferent neurons by their characteristic activation/deactivation kinetics, enhancement by the KV7 activator retigabine, and block by KV7 specific inhibitor XE991. The blocking of KV7 current by different XE991 concentrations suggests that the KV7 current is generated by both KV7.2/7.3 (high affinity) and KV7.5 (low affinity) channels. The KV7 current was inhibited by 300 nM BK in neurons with diameters consistent with both group III and group IV afferents. The inhibition of KV7 by BK could be a mechanism by which this metabolic mediator generates the EPR. Furthermore, our results suggest that KV7 channel activators such as retigabine, could be used to reduce cardiac stress resulting from the exacerbated EPR in patients with cardiovascular disease.NEW & NOTEWORTHY KV7 channels control neuronal excitability. We show that these channels are expressed in muscle afferents and generate currents that are blocked by XE991 and bradykinin (BK). The XE991 block suggests that KV7 current is generated by KV7.2/3 and KV7.5 channels. The BK inhibition of KV7 channels may explain how BK activates the exercise pressor reflex (EPR). Retigabine can enhance KV7 current, which could help control the inappropriately activated EPR in patients with cardiovascular disease.
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Affiliation(s)
- Andrew B Wright
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Khrystyna Yu Sukhanova
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
| | - Keith S Elmslie
- The Baker Laboratory of Pharmacology, Department of Pharmacology, Kirksville College of Osteopathic Medicine, A.T. Still University of Health Sciences, Kirksville, Missouri
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40
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Jepps TA, Barrese V, Miceli F. Editorial: Kv7 Channels: Structure, Physiology, and Pharmacology. Front Physiol 2021; 12:679317. [PMID: 33935812 PMCID: PMC8085343 DOI: 10.3389/fphys.2021.679317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 03/25/2021] [Indexed: 11/27/2022] Open
Affiliation(s)
- Thomas A Jepps
- Vascular Biology Group, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Vincenzo Barrese
- Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, Naples, Italy
| | - Francesco Miceli
- Department of Neuroscience, Reproductive Sciences and Dentistry, University of Naples Federico II, Naples, Italy
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Borgini M, Mondal P, Liu R, Wipf P. Chemical modulation of Kv7 potassium channels. RSC Med Chem 2021; 12:483-537. [PMID: 34046626 PMCID: PMC8128042 DOI: 10.1039/d0md00328j] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/01/2020] [Indexed: 01/10/2023] Open
Abstract
The rising interest in Kv7 modulators originates from their ability to evoke fundamental electrophysiological perturbations in a tissue-specific manner. A large number of therapeutic applications are, in part, based on the clinical experience with two broad-spectrum Kv7 agonists, flupirtine and retigabine. Since precise molecular structures of human Kv7 channel subtypes in closed and open states have only very recently started to emerge, computational studies have traditionally been used to analyze binding modes and direct the development of more potent and selective Kv7 modulators with improved safety profiles. Herein, the synthetic and medicinal chemistry of small molecule modulators and the representative biological properties are summarized. Furthermore, new therapeutic applications supported by in vitro and in vivo assay data are suggested.
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Affiliation(s)
- Matteo Borgini
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
| | - Pravat Mondal
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
| | - Ruiting Liu
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
| | - Peter Wipf
- Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
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Revill AL, Katzell A, Del Negro CA, Milsom WK, Funk GD. KCNQ Current Contributes to Inspiratory Burst Termination in the Pre-Bötzinger Complex of Neonatal Rats in vitro. Front Physiol 2021; 12:626470. [PMID: 33927636 PMCID: PMC8078421 DOI: 10.3389/fphys.2021.626470] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 02/23/2021] [Indexed: 12/23/2022] Open
Abstract
The pre-Bötzinger complex (preBötC) of the ventral medulla generates the mammalian inspiratory breathing rhythm. When isolated in explants and deprived of synaptic inhibition, the preBötC continues to generate inspiratory-related rhythm. Mechanisms underlying burst generation have been investigated for decades, but cellular and synaptic mechanisms responsible for burst termination have received less attention. KCNQ-mediated K+ currents contribute to burst termination in other systems, and their transcripts are expressed in preBötC neurons. Therefore, we tested the hypothesis that KCNQ channels also contribute to burst termination in the preBötC. We recorded KCNQ-like currents in preBötC inspiratory neurons in neonatal rat slices that retain respiratory rhythmicity. Blocking KCNQ channels with XE991 or linopirdine (applied via superfusion or locally) increased inspiratory burst duration by 2- to 3-fold. By contrast, activation of KCNQ with retigabine decreased inspiratory burst duration by ~35%. These data from reduced preparations suggest that the KCNQ current in preBötC neurons contributes to inspiratory burst termination.
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Affiliation(s)
- Ann L. Revill
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | - Alexis Katzell
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
| | | | - William K. Milsom
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Gregory D. Funk
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Physiology, University of Alberta, Edmonton, AB, Canada
- Women and Children’s Health Research Institute, University of Alberta, Edmonton, AB, Canada
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Springer K, Varghese N, Tzingounis AV. Flexible Stoichiometry: Implications for KCNQ2- and KCNQ3-Associated Neurodevelopmental Disorders. Dev Neurosci 2021; 43:191-200. [PMID: 33794528 PMCID: PMC8440324 DOI: 10.1159/000515495] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/25/2021] [Indexed: 11/19/2022] Open
Abstract
KCNQ2 and KCNQ3 pathogenic channel variants have been associated with a spectrum of developmentally regulated diseases that vary in age of onset, severity, and whether it is transient (i.e., benign familial neonatal seizures) or long-lasting (i.e., developmental and epileptic encephalopathy). KCNQ2 and KCNQ3 channels have also emerged as a target for novel antiepileptic drugs as their activation could reduce epileptic activity. Consequently, a great effort has taken place over the last 2 decades to understand the mechanisms that control the assembly, gating, and modulation of KCNQ2 and KCNQ3 channels. The current view that KCNQ2 and KCNQ3 channels assemble as heteromeric channels (KCNQ2/3) forms the basis of our understanding of KCNQ2 and KCNQ3 channelopathies and drug design. Here, we review the evidence that supports the formation of KCNQ2/3 heteromers in neurons. We also highlight functional and transcriptomic studies that suggest channel composition might not be necessarily fixed in the nervous system, but rather is dynamic and flexible, allowing some neurons to express KCNQ2 and KCNQ3 homomers. We propose that to fully understand KCNQ2 and KCNQ3 channelopathies, we need to adopt a more flexible view of KCNQ2 and KCNQ3 channel stoichiometry, which might differ across development, brain regions, cell types, and disease states.
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Affiliation(s)
- Kristen Springer
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Nissi Varghese
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
| | - Anastasios V Tzingounis
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut, USA
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Activation of KCNQ4 as a Therapeutic Strategy to Treat Hearing Loss. Int J Mol Sci 2021; 22:ijms22052510. [PMID: 33801540 PMCID: PMC7958948 DOI: 10.3390/ijms22052510] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/16/2021] [Accepted: 02/22/2021] [Indexed: 12/14/2022] Open
Abstract
Potassium voltage-gated channel subfamily q member 4 (KCNQ4) is a voltage-gated potassium channel that plays essential roles in maintaining ion homeostasis and regulating hair cell membrane potential. Reduction of the activity of the KCNQ4 channel owing to genetic mutations is responsible for nonsyndromic hearing loss, a typically late-onset, initially high-frequency loss progressing over time. In addition, variants of KCNQ4 have also been associated with noise-induced hearing loss and age-related hearing loss. Therefore, the discovery of small compounds activating or potentiating KCNQ4 is an important strategy for the curative treatment of hearing loss. In this review, we updated the current concept of the physiological role of KCNQ4 in the inner ear and the pathologic mechanism underlying the role of KCNQ4 variants with regard to hearing loss. Finally, we focused on currently developed KCNQ4 activators and their pros and cons, paving the way for the future development of specific KCNQ4 activators as a remedy for hearing loss.
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Baird DA, Liu JZ, Zheng J, Sieberts SK, Perumal T, Elsworth B, Richardson TG, Chen CY, Carrasquillo MM, Allen M, Reddy JS, De Jager PL, Ertekin-Taner N, Mangravite LM, Logsdon B, Estrada K, Haycock PC, Hemani G, Runz H, Smith GD, Gaunt TR. Identifying drug targets for neurological and psychiatric disease via genetics and the brain transcriptome. PLoS Genet 2021; 17:e1009224. [PMID: 33417599 PMCID: PMC7819609 DOI: 10.1371/journal.pgen.1009224] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 01/21/2021] [Accepted: 10/26/2020] [Indexed: 11/26/2022] Open
Abstract
Discovering drugs that efficiently treat brain diseases has been challenging. Genetic variants that modulate the expression of potential drug targets can be utilized to assess the efficacy of therapeutic interventions. We therefore employed Mendelian Randomization (MR) on gene expression measured in brain tissue to identify drug targets involved in neurological and psychiatric diseases. We conducted a two-sample MR using cis-acting brain-derived expression quantitative trait loci (eQTLs) from the Accelerating Medicines Partnership for Alzheimer’s Disease consortium (AMP-AD) and the CommonMind Consortium (CMC) meta-analysis study (n = 1,286) as genetic instruments to predict the effects of 7,137 genes on 12 neurological and psychiatric disorders. We conducted Bayesian colocalization analysis on the top MR findings (using P<6x10-7 as evidence threshold, Bonferroni-corrected for 80,557 MR tests) to confirm sharing of the same causal variants between gene expression and trait in each genomic region. We then intersected the colocalized genes with known monogenic disease genes recorded in Online Mendelian Inheritance in Man (OMIM) and with genes annotated as drug targets in the Open Targets platform to identify promising drug targets. 80 eQTLs showed MR evidence of a causal effect, from which we prioritised 47 genes based on colocalization with the trait. We causally linked the expression of 23 genes with schizophrenia and a single gene each with anorexia, bipolar disorder and major depressive disorder within the psychiatric diseases and 9 genes with Alzheimer’s disease, 6 genes with Parkinson’s disease, 4 genes with multiple sclerosis and two genes with amyotrophic lateral sclerosis within the neurological diseases we tested. From these we identified five genes (ACE, GPNMB, KCNQ5, RERE and SUOX) as attractive drug targets that may warrant follow-up in functional studies and clinical trials, demonstrating the value of this study design for discovering drug targets in neuropsychiatric diseases. Genetic association studies have been successful in identifying many genetic variants associated with disease risk, but it has been far more challenging to determine the genes through which these act. This is important, because such genes may encode effective drug targets for these diseases. We used Mendelian randomization (MR) and colocalization, two methods which in combination exploit these genetic variants to estimate the causal effects of individual genes. We applied this approach to 12 neurological and psychiatric diseases using data from the AMP-AD and CMC brain expression quantitative locus dataset, which is large enough to provide robust evidence for the relationship between genetic variants and gene expression. We found a causal relationship between the change in expression of 47 genes and increased disease risk across the 12 diseases we tested. As drug targets with human genetic evidence are far more likely to be approved in clinical trials, these findings provide a valuable list of potential therapeutic targets, including the ACE, GPNMB, KCNQ5, RERE and SUOX genes.
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Affiliation(s)
- Denis A. Baird
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
- * E-mail: (DAB); (TRG)
| | - Jimmy Z. Liu
- Translational Biology, Research and Development, Cambridge, Massachusetts, United States of America
| | - Jie Zheng
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
| | | | | | - Benjamin Elsworth
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Tom G. Richardson
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Chia-Yen Chen
- Translational Biology, Research and Development, Cambridge, Massachusetts, United States of America
| | - Minerva M. Carrasquillo
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, Florida, United States of America
| | - Mariet Allen
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, Florida, United States of America
| | - Joseph S. Reddy
- Department of Health Sciences Research, Mayo Clinic Florida, Jacksonville, Florida, United States of America
| | - Philip L. De Jager
- Centre for Translational & Computational Neuroimmunology, Department of Neurology, Columbia University Medical Centre, New York, New York, United States of America
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Centre, New York, New York, United States of America
| | - Nilufer Ertekin-Taner
- Department of Neuroscience, Mayo Clinic Florida, Jacksonville, Florida, United States of America
- Department of Neurology, Mayo Clinic Florida, Jacksonville, Florida, United States of America
| | | | - Ben Logsdon
- Sage Bionetworks, Seattle, Washington, United States of America
| | - Karol Estrada
- Translational Biology, Research and Development, Cambridge, Massachusetts, United States of America
- BioMarin Pharmaceuticals, San Rafael, California, United States of America
| | - Philip C. Haycock
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Gibran Hemani
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
| | - Heiko Runz
- Translational Biology, Research and Development, Cambridge, Massachusetts, United States of America
| | - George Davey Smith
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
- NIHR Bristol Biomedical Research Centre, Oakfield House, University of Bristol, Bristol, United Kingdom
| | - Tom R. Gaunt
- MRC Integrative Epidemiology Unit (IEU), Population Health Sciences, University of Bristol, Bristol, United Kingdom
- NIHR Bristol Biomedical Research Centre, Oakfield House, University of Bristol, Bristol, United Kingdom
- * E-mail: (DAB); (TRG)
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46
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Liu Y, Bian X, Wang K. Pharmacological Activation of Neuronal Voltage-Gated Kv7/KCNQ/M-Channels for Potential Therapy of Epilepsy and Pain. Handb Exp Pharmacol 2021; 267:231-251. [PMID: 33837465 DOI: 10.1007/164_2021_458] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Native M-current is a low-threshold, slowly activating potassium current that exerts an inhibitory control over neuronal excitability. The M-channel is primarily co-assembled by heterotetrameric Kv7.2/KCNQ2 and Kv7.3/KCNQ3 subunits that are specifically expressed in the brain and peripheral nociceptive and visceral sensory neurons in the spinal cord. Reduction of M-channel function leads to neuronal hyperexcitability that defines the fundamental mechanism of neurological disorders such as epilepsy and pain, indicating that pharmacological activation of Kv7/KCNQ/M-channels may serve the basis for the therapy. The well-known KCNQ opener retigabine (ezogabine or Potiga) was approved by FDA in 2011 as an anticonvulsant used for an adjunctive treatment of partial epilepsies. Unfortunately, retigabine was discontinued in 2017 due to its side effects of blue-colored appearance of the skin and eyes after prolonged intake. In addition, flupirtine, a structural derivative of retigabine and a centrally acting non-opioid analgesic, was also withdrawn in 2018 for liver toxicity. Fortunately, these side effects are compound-structures related and can be avoided. Thus, further identification and development of novel potent and selective Kv7 channel openers may lead to an effective therapy with improved safety window for anti-epilepsy and anti-nociception.
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Affiliation(s)
- Yani Liu
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China
| | - Xiling Bian
- Department of Pharmacology, Peking University School of Pharmaceutical Sciences, Beijing, China
| | - KeWei Wang
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, China. .,Institute of Innovative Drugs Qingdao University, Qingdao, China.
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Abstract
Kv7.1-Kv7.5 (KCNQ1-5) K+ channels are voltage-gated K+ channels with major roles in neurons, muscle cells and epithelia where they underlie physiologically important K+ currents, such as neuronal M current and cardiac IKs. Specific biophysical properties of Kv7 channels make them particularly well placed to control the activity of excitable cells. Indeed, these channels often work as 'excitability breaks' and are targeted by various hormones and modulators to regulate cellular activity outputs. Genetic deficiencies in all five KCNQ genes result in human excitability disorders, including epilepsy, arrhythmias, deafness and some others. Not surprisingly, this channel family attracts considerable attention as potential drug targets. Here we will review biophysical properties and tissue expression profile of Kv7 channels, discuss recent advances in the understanding of their structure as well as their role in various neurological, cardiovascular and other diseases and pathologies. We will also consider a scope for therapeutic targeting of Kv7 channels for treatment of the above health conditions.
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48
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Tsai YM, Jones F, Mullen P, Porter KE, Steele D, Peers C, Gamper N. Vascular Kv7 channels control intracellular Ca 2+ dynamics in smooth muscle. Cell Calcium 2020; 92:102283. [PMID: 32950876 PMCID: PMC7695684 DOI: 10.1016/j.ceca.2020.102283] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 08/21/2020] [Accepted: 08/26/2020] [Indexed: 01/23/2023]
Abstract
Voltage-gated Kv7 (or KCNQ) channels control activity of excitable cells, including vascular smooth muscle cells (VSMCs), by setting their resting membrane potential and controlling other excitability parameters. Excitation-contraction coupling in muscle cells is mediated by Ca2+ but until now, the exact role of Kv7 channels in cytosolic Ca2+ dynamics in VSMCs has not been fully elucidated. We utilised microfluorimetry to investigate the impact of Kv7 channel activity on intracellular Ca2+ levels and electrical activity of rat A7r5 VSMCs and primary human internal mammary artery (IMA) SMCs. Both, direct (XE991) and G protein coupled receptor mediated (vasopressin, AVP) Kv7 channel inhibition induced robust Ca2+ oscillations, which were significantly reduced in the presence of Kv7 channel activator, retigabine, L-type Ca2+ channel inhibitor, nifedipine, or T-type Ca2+ channel inhibitor, NNC 55-0396, in A7r5 cells. Membrane potential measured using FluoVolt exhibited a slow depolarisation followed by a burst of sharp spikes in response to XE991; spikes were temporally correlated with Ca2+ oscillations. Phospholipase C inhibitor (edelfosine) reduced AVP-induced, but not XE991-induced Ca2+ oscillations. AVP and XE991 induced a large increase of [Ca2+]i in human IMA, which was also attenuated with retigabine, nifedipine and NNC 55-0396. RT-PCR, immunohistochemistry and electrophysiology suggested that Kv7.5 was the predominant Kv7 subunit in both rat and human arterial SMCs; CACNA1C (Cav1.2; L-type) and CACNA1 G (Cav3.1; T-type) were the most abundant voltage-gated Ca2+ channel gene transcripts in both types of VSMCs. This study establishes Kv7 channels as key regulators of Ca2+ signalling in VSMCs with Kv7.5 playing a dominant role.
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Affiliation(s)
- Yuan-Ming Tsai
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom; Division of Thoracic Surgery, Department of Surgery, Tri-Service General Hospital, National Defence Medical Centre, Taipei 11490, Taiwan.
| | - Frederick Jones
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Pierce Mullen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Karen E Porter
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Derek Steele
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Chris Peers
- Leeds Institute of Cardiovascular and Metabolic Medicine, Faculty of Medicine and Health, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - Nikita Gamper
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, United Kingdom.
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49
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Dirkx N, Miceli F, Taglialatela M, Weckhuysen S. The Role of Kv7.2 in Neurodevelopment: Insights and Gaps in Our Understanding. Front Physiol 2020; 11:570588. [PMID: 33192566 PMCID: PMC7657400 DOI: 10.3389/fphys.2020.570588] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 09/07/2020] [Indexed: 11/13/2022] Open
Abstract
Kv7.2 subunits encoded by the KCNQ2 gene constitute a critical molecular component of the M-current, a subthreshold voltage-gated potassium current controlling neuronal excitability by dampening repetitive action potential firing. Pathogenic loss-of-function variants in KCNQ2 have been linked to epilepsy since 1998, and there is ample functional evidence showing that dysfunction of the channel indeed results in neuronal hyperexcitability. The recent description of individuals with severe developmental delay with or without seizures due to pathogenic variants in KCNQ2 (KCNQ2-encephalopathy) reveals that Kv7.2 channels also have an important role in neurodevelopment. Kv7.2 channels are expressed already very early in the developing brain when key developmental processes such as proliferation, differentiation, and synaptogenesis play a crucial role in brain morphogenesis and maturation. In this review, we will discuss the available evidence for a role of Kv7.2 channels in these neurodevelopmental processes, focusing in particular on insights derived from KCNQ2-related human phenotypes, from the spatio-temporal expression of Kv7.2 and other Kv7 family member, and from cellular and rodent models, highlighting critical gaps and research strategies to be implemented in the future. Lastly, we propose a model which divides the M-current activity in three different developmental stages, correlating with the cell characteristics during these particular periods in neuronal development, and how this can be linked with KCNQ2-related disorders. Understanding these mechanisms can create opportunities for new targeted therapies for KCNQ2-encephalopathy.
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Affiliation(s)
- Nina Dirkx
- Applied and Translational Neurogenomics Group, VIB Center for Molecular Neurology, Vlaams Instituut voor Biotechnologie, Antwerp, Belgium
| | - Francesco Miceli
- Section of Pharmacology, Department of Neuroscience, University of Naples Federico II, Naples, Italy
| | - Maurizio Taglialatela
- Section of Pharmacology, Department of Neuroscience, University of Naples Federico II, Naples, Italy
| | - Sarah Weckhuysen
- Applied and Translational Neurogenomics Group, VIB Center for Molecular Neurology, Vlaams Instituut voor Biotechnologie, Antwerp, Belgium.,Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.,Department of Neurology, Antwerp University Hospital, Antwerp, Belgium
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50
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Changes in expression of Kv7.5 and Kv7.2 channels in dorsal root ganglion neurons in the streptozotocin rat model of painful diabetic neuropathy. Neurosci Lett 2020; 736:135277. [PMID: 32739272 DOI: 10.1016/j.neulet.2020.135277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 07/21/2020] [Accepted: 07/22/2020] [Indexed: 11/21/2022]
Abstract
Diabetic peripheral neuropathic pain (DPNP), the most debilitating complication of diabetes mellitus, is resistant to current therapy. The pathogenesis of DPNP is still elusive, but several mechanisms have been proposed including abnormal hyperexcitability of dorsal root ganglion (DRG) neurons. The underlying molecular mechanisms of such aberrant hyperexcitability are incompletely understood. Using the streptozotocin (STZ) rat model of DPNP, we have recently provided evidence implicating neuronal Kv7 channels that normally exert a powerful stabilizing influence on neuronal excitability, in the abnormal hyperexcitability of DRG neurons and in pain hypersensitivity associated with DPNP. In the present immunohistochemical study, we sought to determine whether Kv7.2 and/or Kv7.5 channel expression is altered in DRG neurons in STZ rats. We found 35 days post-STZ: (1) a significant decrease in Kv7.5-immunoreactivity in small (<30 μm) DRG neurons (both IB4 positive and IB4 negative) and medium-sized (30-40 μm) neurons, and (2) a significant increase in Kv7.2-immunoreactivity in small (<30 μm) neurons, and a non-significant increase in medium/large neurons. The decrease in Kv7.5 channel expression in small and medium-sized DRG neurons in STZ rats is likely to contribute to the mechanisms of hyperexcitability of these neurons and thereby to the resulting pain hypersensitivity associated with DPNP. The upregulation of Kv7.2 subunit in small DRG neurons may be an activity dependent compensatory mechanism to limit STZ-induced hyperexcitability of DRG neurons and the associated pain hypersensitivity. The findings support the notion that Kv7 channels may represent a novel target for DPNP treatment.
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