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1.
Molecules ; 29(13)2024 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-38999185

RESUMEN

The growing interest in Kv7.2/7.3 agonists originates from the involvement of these channels in several brain hyperexcitability disorders. In particular, Kv7.2/7.3 mutants have been clearly associated with epileptic encephalopathies (DEEs) as well as with a spectrum of focal epilepsy disorders, often associated with developmental plateauing or regression. Nevertheless, there is a lack of available therapeutic options, considering that retigabine, the only molecule used in clinic as a broad-spectrum Kv7 agonist, has been withdrawn from the market in late 2016. This is why several efforts have been made both by both academia and industry in the search for suitable chemotypes acting as Kv7.2/7.3 agonists. In this context, in silico methods have played a major role, since the precise structures of different Kv7 homotetramers have been only recently disclosed. In the present review, the computational methods used for the design of Kv.7.2/7.3 small molecule agonists and the underlying medicinal chemistry are discussed in the context of their biological and structure-function properties.


Asunto(s)
Canal de Potasio KCNQ2 , Canal de Potasio KCNQ3 , Humanos , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/química , Canal de Potasio KCNQ3/metabolismo , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/química , Canal de Potasio KCNQ3/antagonistas & inhibidores , Simulación por Computador , Relación Estructura-Actividad , Descubrimiento de Drogas/métodos , Animales
2.
J Physiol ; 602(15): 3769-3791, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38976504

RESUMEN

Fragile X syndrome (FXS), the most frequent monogenic form of intellectual disability, is caused by transcriptional silencing of the FMR1 gene that could render neuronal hyperexcitability. Here we show that pyramidal cells (PCs) in the dorsal CA1 region of the hippocampus elicited a larger action potential (AP) number in response to suprathreshold stimulation in juvenile Fmr1 knockout (KO) than wild-type (WT) mice. Because Kv7/M channels modulate CA1 PC excitability in rats, we investigated if their dysfunction produces neuronal hyperexcitability in Fmr1 KO mice. Immunohistochemical and western blot analyses showed no differences in the expression of Kv7.2 and Kv7.3 channel subunits between genotypes; however, the current mediated by Kv7/M channels was reduced in Fmr1 KO mice. In both genotypes, bath application of XE991 (10 µM), a blocker of Kv7/M channels: produced an increased AP number, produced an increased input resistance, produced a decreased AP voltage threshold and shaped AP medium afterhyperpolarization by increasing mean velocities. Retigabine (10 µM), an opener of Kv7/M channels, produced opposite effects to XE991. Both XE991 and retigabine abolished differences in all these parameters found in control conditions between genotypes. Furthermore, a low concentration of retigabine (2.5 µM) normalized CA1 PC excitability of Fmr1 KO mice. Finally, ex vivo seizure-like events evoked by 4-aminopyiridine (200 µM) in the dorsal CA1 region were more frequent in Fmr1 KO mice, and were abolished by retigabine (5-10 µM). We conclude that CA1 PCs of Fmr1 KO mice exhibit hyperexcitability, caused by Kv7/M channel dysfunction, and increased epileptiform activity, which were abolished by retigabine. KEY POINTS: Dorsal pyramidal cells of the hippocampal CA1 region of Fmr1 knockout mice exhibit hyperexcitability. Kv7/M channel activity, but not expression, is reduced in pyramidal cells of the hippocampal CA1 region of Fmr1 knockout mice. Kv7/M channel dysfunction causes hyperexcitability in pyramidal cells of the hippocampal CA1 region of Fmr1 knockout mice by increasing input resistance, decreasing AP voltage threshold and shaping medium afterhyperpolarization. A Kv7/M channel opener normalizes neuronal excitability in pyramidal cells of the hippocampal CA1 region of Fmr1 knockout mice. Ex vivo seizure-like events evoked in the dorsal CA1 region were more frequent in Fmr1 KO mice, and such an epileptiform activity was abolished by a Kv7/M channel opener depending on drug concentration. Kv7/M channels may represent a therapeutic target for treating symptoms associated with hippocampal alterations in fragile X syndrome.


Asunto(s)
Potenciales de Acción , Región CA1 Hipocampal , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Ratones Noqueados , Fenilendiaminas , Células Piramidales , Animales , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil/genética , Células Piramidales/fisiología , Células Piramidales/metabolismo , Células Piramidales/efectos de los fármacos , Fenilendiaminas/farmacología , Región CA1 Hipocampal/fisiopatología , Región CA1 Hipocampal/metabolismo , Ratones , Carbamatos/farmacología , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Antracenos/farmacología , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo , Masculino , Ratones Endogámicos C57BL , Síndrome del Cromosoma X Frágil/fisiopatología , Síndrome del Cromosoma X Frágil/genética , Proteínas del Tejido Nervioso
3.
J Gen Physiol ; 156(7)2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38832889

RESUMEN

Voltage-gated ion channels are responsible for the electrical excitability of neurons and cardiomyocytes. Thus, they are obvious targets for pharmaceuticals aimed to modulate excitability. Compounds activating voltage-gated potassium (KV) channels are expected to reduce excitability. To search for new KV-channel activators, we performed a high-throughput screen of 10,000 compounds on a specially designed Shaker KV channel. Here, we report on a large family of channel-activating compounds with a carboxyl (COOH) group as the common motif. The most potent COOH activators are lipophilic (4 < LogP <7) and are suggested to bind at the interface between the lipid bilayer and the channel's positively charged voltage sensor. The negatively charged form of the COOH-group compounds is suggested to open the channel by electrostatically pulling the voltage sensor to an activated state. Several of the COOH-group compounds also activate the therapeutically important KV7.2/7.3 channel and can thus potentially be developed into antiseizure drugs. The COOH-group compounds identified in this study are suggested to act via the same site and mechanism of action as previously studied COOH-group compounds, such as polyunsaturated fatty acids and resin acids, but distinct from sites for several other types of potassium channel-activating compounds.


Asunto(s)
Activación del Canal Iónico , Animales , Activación del Canal Iónico/efectos de los fármacos , Canales de Potasio de la Superfamilia Shaker/metabolismo , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ2/agonistas , Canales de Potasio con Entrada de Voltaje/metabolismo , Canales de Potasio con Entrada de Voltaje/efectos de los fármacos , Canal de Potasio KCNQ3/metabolismo , Humanos , Xenopus laevis
4.
J Affect Disord ; 359: 364-372, 2024 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-38772507

RESUMEN

Depression, a complex disorder with significant treatment challenges, necessitates innovative therapeutic approaches to address its multifaceted nature and enhance treatment outcomes. The modulation of KCNQ potassium (K+) channels, pivotal regulators of neuronal excitability and neurotransmitter release, is a promising innovative therapeutic target in psychiatry. Widely expressed across various tissues, including the nervous and cardiovascular systems, KCNQ channels play a crucial role in modulating membrane potential and regulating neuronal activity. Recent preclinical evidence suggests that KCNQ channels, particularly KCNQ3, contribute to the regulation of neuronal excitability within the reward circuitry, offering a potential target for alleviating depressive symptoms, notably anhedonia. Studies using animal models demonstrate that interventions targeting KCNQ channels can restore dopaminergic firing balance and mitigate depressive symptoms. Human studies investigating the effects of KCNQ channel activators, such as ezogabine, have shown promising results in alleviating depressive symptoms and anhedonia. The aforementioned observations underscore the therapeutic potential of KCNQ channel modulation in depression management and highlight the need and justification for phase 2 and phase 3 dose-finding studies as well as studies prespecifying symptomatic targets in depression including anhedonia.


Asunto(s)
Antidepresivos , Carbamatos , Trastorno Depresivo Mayor , Canales de Potasio KCNQ , Fenilendiaminas , Animales , Humanos , Anhedonia/efectos de los fármacos , Anhedonia/fisiología , Antidepresivos/uso terapéutico , Antidepresivos/farmacología , Carbamatos/farmacología , Carbamatos/uso terapéutico , Trastorno Depresivo Mayor/tratamiento farmacológico , Canales de Potasio KCNQ/agonistas , Canales de Potasio KCNQ/metabolismo , Canal de Potasio KCNQ3/genética , Fenilendiaminas/farmacología , Fenilendiaminas/uso terapéutico
5.
Epilepsy Res ; 200: 107296, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38219422

RESUMEN

Mutations within the Kv7.2 and Kv7.3 genes are well described causes for genetic childhood epilepsies. Knowledge on these channels in acquired focal epilepsy, especially in mesial temporal lobe epilepsy (mTLE), however, is scarce. Here, we used the rat pilocarpine model of drug-resistant mTLE to elucidate both expression and function by quantitative polymerase-chain reaction, immunohistochemistry, and electrophysiology, respectively. We found transcriptional downregulation of Kv7.2 and Kv7.3 as well as reduced Kv7.2 expression in epileptic CA1. Consequences were altered synaptic transmission, hyperexcitability which consisted of epileptiform afterpotentials, and increased susceptibility to acute GABAergic disinhibition. Importantly, blocking Kv7 channels with XE991 increased hyperexcitability in control tissue, but not in chronically epileptic tissue suggesting that the Kv7 deficit had precluded XE991 effects in this tissue. Conversely, XE991 resulted in comparable reduction of the paired-pulse ratio in both experimental groups implying preserved presynaptic Kv7.2 function of Schaffer collateral terminals. Consistent with Kv7.2/7.3 downregulation, the Kv7.3 channel opener ß-hydroxybutyrate failed to mitigate hyperexcitability. Our findings demonstrate that compromised Kv7 function is not only relevant in genetic epilepsy, but also in acquired focal epilepsy. Moreover, they help explain reduced anti-seizure efficacy of Kv7 channel openers in drug-resistant epilepsy.


Asunto(s)
Epilepsia del Lóbulo Temporal , Animales , Niño , Humanos , Ratas , Regulación hacia Abajo , Epilepsia del Lóbulo Temporal/inducido químicamente , Epilepsia del Lóbulo Temporal/genética , Epilepsia del Lóbulo Temporal/metabolismo , Potenciales de la Membrana , Pilocarpina , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ3/genética
6.
J Pharmacol Exp Ther ; 389(1): 118-127, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38290975

RESUMEN

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.


Asunto(s)
Canal de Potasio KCNQ2 , Canal de Potasio KCNQ3 , Ratones , Animales , Potenciales de la Membrana , Potenciales de Acción , Células Receptoras Sensoriales
7.
Nat Commun ; 14(1): 6632, 2023 10 19.
Artículo en Inglés | MEDLINE | ID: mdl-37857637

RESUMEN

The human voltage-gated potassium channel KCNQ2/KCNQ3 carries the neuronal M-current, which helps to stabilize the membrane potential. KCNQ2 can be activated by analgesics and antiepileptic drugs but their activation mechanisms remain unclear. Here we report cryo-electron microscopy (cryo-EM) structures of human KCNQ2-CaM in complex with three activators, namely the antiepileptic drug cannabidiol (CBD), the lipid phosphatidylinositol 4,5-bisphosphate (PIP2), and HN37 (pynegabine), an antiepileptic drug in the clinical trial, in an either closed or open conformation. The activator-bound structures, along with electrophysiology analyses, reveal the binding modes of two CBD, one PIP2, and two HN37 molecules in each KCNQ2 subunit, and elucidate their activation mechanisms on the KCNQ2 channel. These structures may guide the development of antiepileptic drugs and analgesics that target KCNQ2.


Asunto(s)
Analgésicos , Anticonvulsivantes , Humanos , Anticonvulsivantes/farmacología , Microscopía por Crioelectrón , Ligandos , Potenciales de la Membrana , Canal de Potasio KCNQ2/química , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ3/metabolismo
8.
Life Sci Alliance ; 6(12)2023 12.
Artículo en Inglés | MEDLINE | ID: mdl-37748809

RESUMEN

Voltage-sensitive potassium channels play an important role in controlling membrane potential and ionic homeostasis in the gut and have been implicated in gastrointestinal (GI) cancers. Through large-scale analysis of 897 patients with gastro-oesophageal adenocarcinomas (GOAs) coupled with in vitro models, we find KCNQ family genes are mutated in ∼30% of patients, and play therapeutically targetable roles in GOA cancer growth. KCNQ1 and KCNQ3 mediate the WNT pathway and MYC to increase proliferation through resultant effects on cadherin junctions. This also highlights novel roles of KCNQ3 in non-excitable tissues. We also discover that activity of KCNQ3 sensitises cancer cells to existing potassium channel inhibitors and that inhibition of KCNQ activity reduces proliferation of GOA cancer cells. These findings reveal a novel and exploitable role of potassium channels in the advancement of human cancer, and highlight that supplemental treatments for GOAs may exist through KCNQ inhibitors.


Asunto(s)
Adenocarcinoma , Canales de Potasio KCNQ , Humanos , Canales de Potasio KCNQ/genética , Canales de Potasio KCNQ/metabolismo , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo , Canal de Potasio KCNQ2/fisiología , Adenocarcinoma/genética
9.
J Neurosci ; 43(38): 6479-6494, 2023 09 20.
Artículo en Inglés | MEDLINE | ID: mdl-37607817

RESUMEN

Gain-of-function (GOF) pathogenic variants in the potassium channels KCNQ2 and KCNQ3 lead to hyperexcitability disorders such as epilepsy and autism spectrum disorders. However, the underlying cellular mechanisms of how these variants impair forebrain function are unclear. Here, we show that the R201C variant in KCNQ2 has opposite effects on the excitability of two types of mouse pyramidal neurons of either sex, causing hyperexcitability in layer 2/3 (L2/3) pyramidal neurons and hypoexcitability in CA1 pyramidal neurons. Similarly, the homologous R231C variant in KCNQ3 leads to hyperexcitability in L2/3 pyramidal neurons and hypoexcitability in CA1 pyramidal neurons. However, the effects of KCNQ3 gain-of-function on excitability are specific to superficial CA1 pyramidal neurons. These findings reveal a new level of complexity in the function of KCNQ2 and KCNQ3 channels in the forebrain and provide a framework for understanding the effects of gain-of-function variants and potassium channels in the brain.SIGNIFICANCE STATEMENT KCNQ2/3 gain-of-function (GOF) variants lead to severe forms of neurodevelopmental disorders, but the mechanisms by which these channels affect neuronal activity are poorly understood. In this study, using a series of transgenic mice we demonstrate that the same KCNQ2/3 GOF variants can lead to either hyperexcitability or hypoexcitability in different types of pyramidal neurons [CA1 vs layer (L)2/3]. Additionally, we show that expression of the recurrent KCNQ2 GOF variant R201C in forebrain pyramidal neurons could lead to seizures and SUDEP. Our data suggest that the effects of KCNQ2/3 GOF variants depend on specific cell types and brain regions, possibly accounting for the diverse range of phenotypes observed in individuals with KCNQ2/3 GOF variants.


Asunto(s)
Mutación con Ganancia de Función , Canal de Potasio KCNQ2 , Canal de Potasio KCNQ3 , Trastornos del Neurodesarrollo , Animales , Ratones , Canal de Potasio KCNQ2/genética , Ratones Transgénicos , Canales de Potasio , Prosencéfalo , Células Piramidales , Canal de Potasio KCNQ3/genética
10.
J Neurosci ; 43(43): 7073-7083, 2023 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-37648450

RESUMEN

Neuronal Kv7 voltage-gated potassium channels generate the M-current and regulate neuronal excitability. Here, we report that dehydroepiandrosterone sulfate (DHEAS) is an endogenous Kv7 channel modulator that attenuates Gq-coupled receptor-induced M-current suppression. DHEAS reduced muscarinic agonist-induced Kv7-current suppression of Kv7.1, Kv7.2, Kv7.4, or Kv7.5 homomeric currents and endogenous M-currents in rat sympathetic ganglion neurons. However, DHEAS per se did not alter the voltage dependence of these Kv7 homomeric channels or the m1 receptor-induced activation of phospholipase C or protein kinase C. DHEAS-treated Kv7.2 homomeric currents became resistant to depletion of phosphatidylinositol 4,5-bisphosphate (PIP2) induced by voltage-activated phosphatase, Ci-VSP or eVSP. Our computational models predicted a novel binding site for DHEAS in the cytoplasmic domain of Kv7 subunits. A single-point mutation of the predicted key histidine into cysteine in the rat Kv7.2 subunit, rKv7.2(H558C), resulted in a loss of effects of DHEAS on muscarinic Kv7 current suppression. Furthermore, in vivo administration of DHEAS in mice of both sexes reduced late phase pain responses in the formalin paw test. However, it did not have effects on early phase responses in the formalin paw test or responses in the hot plate test. Coadministration of a selective Kv7 inhibitor, XE991, and DHEAS eliminated analgesic effects of DHEAS in late phase responses in the formalin paw test. Collectively, these results suggest that DHEAS attenuates M-current suppression by stabilizing PIP2-Kv7 subunit interaction and can mitigate inflammatory pain.SIGNIFICANCE STATEMENT M-current suppression induced by stimulation of Gq-coupled receptors is a form of Kv7 current modulation that can reversibly increase neuronal excitability. This study demonstrates that DHEAS, an endogenous steroid hormone, is a novel Kv7 channel modulator that can attenuate M-current suppression without affecting basal Kv7 channel kinetics. Administration of DHEAS in vivo alleviated inflammatory pain in rodents. These results suggest that the degree of M-current suppression can be dynamically regulated by small molecules. Therefore, this novel form of Kv7 channel regulation holds promising potential as a therapeutic target for sensitized nervous activities, such as inflammatory pain.


Asunto(s)
Canal de Potasio KCNQ2 , Agonistas Muscarínicos , Masculino , Femenino , Ratones , Ratas , Animales , Sulfato de Deshidroepiandrosterona , Canal de Potasio KCNQ2/metabolismo , Agonistas Muscarínicos/farmacología , Dolor/tratamiento farmacológico , Formaldehído , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo
11.
Nat Commun ; 14(1): 3547, 2023 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-37321992

RESUMEN

Autism spectrum disorders (ASD) represent neurodevelopmental disorders characterized by social deficits, repetitive behaviors, and various comorbidities, including epilepsy. ANK2, which encodes a neuronal scaffolding protein, is frequently mutated in ASD, but its in vivo functions and disease-related mechanisms are largely unknown. Here, we report that mice with Ank2 knockout restricted to cortical and hippocampal excitatory neurons (Ank2-cKO mice) show ASD-related behavioral abnormalities and juvenile seizure-related death. Ank2-cKO cortical neurons show abnormally increased excitability and firing rate. These changes accompanied decreases in the total level and function of the Kv7.2/KCNQ2 and Kv7.3/KCNQ3 potassium channels and the density of these channels in the enlengthened axon initial segment. Importantly, the Kv7 agonist, retigabine, rescued neuronal excitability, juvenile seizure-related death, and hyperactivity in Ank2-cKO mice. These results suggest that Ank2 regulates neuronal excitability by regulating the length of and Kv7 density in the AIS and that Kv7 channelopathy is involved in Ank2-related brain dysfunctions.


Asunto(s)
Epilepsia , Canales de Potasio KCNQ , Animales , Ratones , Epilepsia/metabolismo , Canales de Potasio KCNQ/genética , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ3/metabolismo , Neuronas/metabolismo , Convulsiones/genética , Convulsiones/metabolismo
12.
Commun Biol ; 6(1): 644, 2023 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-37322081

RESUMEN

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.


Asunto(s)
Plantas Medicinales , Rosmarinus , Canal de Potasio KCNQ3/química , Canal de Potasio KCNQ2/química , Isoformas de Proteínas
13.
Acta Pharmacol Sin ; 44(8): 1589-1599, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-36932231

RESUMEN

Mutations in the KCNQ2 gene encoding KV7.2 subunit that mediates neuronal M-current cause a severe form of developmental and epileptic encephalopathy (DEE). Electrophysiological evaluation of KCNQ2 mutations has been proved clinically useful in improving outcome prediction and choosing rational anti-seizure medications (ASMs). In this study we described the clinical characteristics, electrophysiological phenotypes and the in vitro response to KCNQ openers of five KCNQ2 pore mutations (V250A, N258Y, H260P, A265T and G290S) from seven patients diagnosed with KCNQ2-DEE. The KCNQ2 variants were transfected into Chinese hamster ovary (CHO) cells alone, in combination with KCNQ3 (1:1) or with wild-type KCNQ2 (KCNQ2-WT) and KCNQ3 in a ratio of 1:1:2, respectively. Their expression and electrophysiological function were assessed. When transfected alone or in combination with KCNQ3, none of these mutations affected the membrane expression of KCNQ2, but most failed to induce a potassium current except A265T, in which trace currents were observed when co-transfected with KCNQ3. When co-expressed with KCNQ2-WT and KCNQ3 (1:1:2), the currents at 0 mV of these mutations were decreased by 30%-70% compared to the KCNQ2/3 channel, which could be significantly rescued by applying KCNQ openers including the approved antiepileptic drug retigabine (RTG, 10 µM), as well as two candidates subjected to clinical trials, pynegabine (HN37, 1 µM) and XEN1101 (1 µM). These newly identified pathologic variants enrich the KCNQ2-DEE mutation hotspots in the pore-forming domain. This electrophysiological study provides a rational basis for personalized therapy with KCNQ openers in DEE patients carrying loss-of-function (LOF) mutations in KCNQ2.


Asunto(s)
Encefalopatías , Canal de Potasio KCNQ2 , Cricetinae , Animales , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo , Células CHO , Cricetulus , Mutación , Encefalopatías/genética
14.
Pharmacology ; 108(2): 138-146, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36516801

RESUMEN

INTRODUCTION: Voltage-gated Kv7/M potassium channels play an essential role in the control of membrane potential and neuronal excitability. Fangchinoline, a bisbenzylisoquinoline alkaloid, displays extensive biological activities including antitumor, anti-inflammatory, and antihypertension effects. In this study, we investigated the effects of fangchinoline on Kv7/M channels. METHODS: A perforated whole-cell patch technique was used to record Kv7 currents from HEK293 cells and M-type currents from mouse dorsal root ganglion (DRG) neurons. RESULTS: Fangchinoline inhibited Kv7.2/Kv7.3 currents in a concentration-dependent manner, with an IC50 of 9.5 ± 1.2 µM. Fangchinoline significantly inhibited Kv7.1, Kv7.2, Kv7.3, Kv7.4, and Kv7.3/Kv7.5 channels without selective effects. Furthermore, fangchinoline significantly slowed the activation of Kv7.1-Kv7.5 channels and inhibited native M-channel currents of DRG neurons. CONCLUSION: Taken together, our findings indicate that fangchinoline concentration-dependently inhibited Kv7/M channel currents.


Asunto(s)
Bencilisoquinolinas , Humanos , Ratones , Animales , Células HEK293 , Potenciales de la Membrana , Bencilisoquinolinas/farmacología , Canal de Potasio KCNQ2 , Canal de Potasio KCNQ3
15.
J Biol Chem ; 299(2): 102819, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36549648

RESUMEN

Zinc (Zn) is an essential trace element; it serves as a cofactor for a great number of enzymes, transcription factors, receptors, and other proteins. Zinc is also an important signaling molecule, which can be released from intracellular stores into the cytosol or extracellular space, for example, during synaptic transmission. Amongst cellular effects of zinc is activation of Kv7 (KCNQ, M-type) voltage-gated potassium channels. Here, we investigated relationships between Kv7 channel inhibition by Ca2+/calmodulin (CaM) and zinc-mediated potentiation. We show that Zn2+ ionophore, zinc pyrithione (ZnPy), can prevent or reverse Ca2+/CaM-mediated inhibition of Kv7.2. In the presence of both Ca2+ and Zn2+, the Kv7.2 channels lose most of their voltage dependence and lock in an open state. In addition, we demonstrate that mutations that interfere with CaM binding to Kv7.2 and Kv7.3 reduced channel membrane abundance and activity, but these mutants retained zinc sensitivity. Moreover, the relative efficacy of ZnPy to activate these mutants was generally greater, compared with the WT channels. Finally, we show that zinc sensitivity was retained in Kv7.2 channels assembled with mutant CaM with all four EF hands disabled, suggesting that it is unlikely to be mediated by CaM. Taken together, our findings indicate that zinc is a potent Kv7 stabilizer, which may protect these channels from physiological inhibitory effects of neurotransmitters and neuromodulators, protecting neurons from overactivity.


Asunto(s)
Calcio , Calmodulina , Espacio Intracelular , Canales de Potasio KCNQ , Zinc , Señalización del Calcio , Calmodulina/metabolismo , Canales de Potasio KCNQ/antagonistas & inhibidores , Canales de Potasio KCNQ/química , Canales de Potasio KCNQ/genética , Canales de Potasio KCNQ/metabolismo , Mutación , Unión Proteica/genética , Zinc/farmacología , Zinc/metabolismo , Espacio Intracelular/metabolismo , Calcio/metabolismo , Canal de Potasio KCNQ2/antagonistas & inhibidores , Canal de Potasio KCNQ2/química , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ3/antagonistas & inhibidores , Canal de Potasio KCNQ3/química , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo
16.
Acta Neurol Scand ; 146(6): 699-707, 2022 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-36225112

RESUMEN

With the development and application of next-generation sequencing technology, the aetiological diagnosis of genetic epilepsy is rapidly becoming easier and less expensive. Additionally, there is a growing body of research into precision therapy based on genetic diagnosis. The numerous genes in the potassium ion channel family constitute the largest family of ion channels: this family is divided into different subtypes. Potassium ion channels play a crucial role in the electrical activity of neurons and are directly involved in the mechanism of epileptic seizures. In China, scientific research on genetic diagnosis and studies of precision therapy for genetic epilepsy are progressing rapidly. Many cases of epilepsy caused by mutation of potassium channel genes have been identified, and several potassium channel gene targets and drug candidates have been discovered. The purpose of this review is to briefly summarize the progress of research on the precise diagnosis and treatment of potassium ion channel-related genetic epilepsy, especially the research conducted in China. Here in, we review several large cohort studies on the genetic diagnosis of epilepsy in China in recent years, summarized the proportion of potassium channel genes. We focus on the progress of precison therapy on some hot epilepsy related potassium channel genes: KCNA1, KCNA2, KCNB1, KCNC1, KCND2, KCNQ2, KCNQ3, KCNMA1, and KCNT1.


Asunto(s)
Epilepsia , Canales de Potasio , Humanos , Canales de Potasio/genética , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ2/genética , Epilepsia/diagnóstico , Epilepsia/genética , Mutación/genética , Canales de Potasio Shaw/genética , Canales de potasio activados por Sodio/genética , Proteínas del Tejido Nervioso/genética
17.
J Med Chem ; 65(16): 11340-11364, 2022 08 25.
Artículo en Inglés | MEDLINE | ID: mdl-35972998

RESUMEN

Neuronal Kv7 channels represent important pharmacological targets for hyperexcitability disorders including epilepsy. Retigabine is the prototype Kv7 activator clinically approved for seizure treatment; however, severe side effects associated with long-term use have led to its market discontinuation. Building upon the recently described cryoEM structure of Kv7.2 complexed with retigabine and on previous structure-activity relationship studies, a small library of retigabine analogues has been designed, synthesized, and characterized for their Kv7 opening ability using both fluorescence- and electrophysiology-based assays. Among all tested compounds, 60 emerged as a potent and photochemically stable neuronal Kv7 channel activator. Compared to retigabine, compound 60 displayed a higher brain/plasma distribution ratio, a longer elimination half-life, and more potent and effective anticonvulsant effects in an acute seizure model in mice. Collectively, these data highlight compound 60 as a promising lead compound for the development of novel Kv7 activators for the treatment of hyperexcitability diseases.


Asunto(s)
Anticonvulsivantes , Canal de Potasio KCNQ3 , Animales , Anticonvulsivantes/química , Anticonvulsivantes/farmacología , Anticonvulsivantes/uso terapéutico , Carbamatos , Canal de Potasio KCNQ2 , Ratones , Fenilendiaminas/química , Fenilendiaminas/farmacología , Fenilendiaminas/uso terapéutico , Convulsiones/inducido químicamente , Convulsiones/tratamiento farmacológico
18.
Neuron ; 110(14): 2201-2203, 2022 07 20.
Artículo en Inglés | MEDLINE | ID: mdl-35863316

RESUMEN

In this issue of Neuron, Lopez et al. report that KCNQ2 (potassium voltage-gated channel subfamily Q member 2) is essential for the sustained antidepressant-like effects of ketamine in glutamatergic neurons of the ventral hippocampus. This study implies that KCNQ2 activators can be novel antidepressants without the ketamine side effects.


Asunto(s)
Canal de Potasio KCNQ3 , Ketamina , Antidepresivos/farmacología , Hipocampo/metabolismo , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Ketamina/farmacología
19.
J Child Neurol ; 37(6): 517-523, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35384780

RESUMEN

BACKGROUND AND PURPOSE: Mutations in KCNQ3 have classically been associated with benign familial neonatal and infantile seizures and more recently identified in patients with neurodevelopmental disorders and abnormal electroencephalogram (EEG) findings. We present 4 affected patients from a family with a pathogenic mutation in KCNQ3 with a unique constellation of clinical findings. METHODS: A family of 3 affected siblings and mother sharing a KCNQ3 pathogenic variant are described, including clinical history, genetic results, and EEG and magnetic resonance imaging (MRI) findings. RESULTS: This family shows a variety of clinical manifestations, including neonatal seizures, developmental delays, autism spectrum disorder, and anxiety. One child developed absence epilepsy, 2 children have infrequent convulsive seizures that have persisted into childhood, and their parent developed adult-onset epilepsy. An underlying c.1091G>A (R364H) variant in KCNQ3 was found in all affected individuals. CONCLUSIONS: The phenotypic variability of KCNQ3 channelopathies continues to expand as more individuals and families are described, and the variant identified in this family adds to the understanding of the manifestations of KCNQ3-related disorders.


Asunto(s)
Epilepsia Benigna Neonatal , Epilepsia , Canal de Potasio KCNQ3 , Adulto , Trastorno del Espectro Autista/genética , Niño , Epilepsia/genética , Epilepsia Benigna Neonatal/genética , Humanos , Recién Nacido , Canal de Potasio KCNQ3/genética , Convulsiones/genética
20.
Pflugers Arch ; 474(7): 721-732, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35459955

RESUMEN

KCNQ channels participate in the physiology of several cell types. In neurons of the central nervous system, the primary subunits are KCNQ2, 3, and 5. Activation of these channels silence the neurons, limiting action potential duration and preventing high-frequency action potential burst. Loss-of-function mutations of the KCNQ channels are associated with a wide spectrum of phenotypes characterized by hyperexcitability. Hence, pharmacological activation of these channels is an attractive strategy to treat epilepsy and other hyperexcitability conditions as are the evolution of stroke and traumatic brain injury. In this work we show that triclosan, a bactericide widely used in personal care products, activates the KCNQ3 channels but not the KCNQ2. Triclosan induces a voltage shift in the activation, increases the conductance, and slows the closing of the channel. The response is independent of PIP2. Molecular docking simulations together with site-directed mutagenesis suggest that the putative binding site is in the voltage sensor domain. Our results indicate that triclosan is a new activator for KCNQ channels.


Asunto(s)
Epilepsia , Triclosán , Epilepsia/metabolismo , Humanos , Canales de Potasio KCNQ/metabolismo , Canal de Potasio KCNQ1 , Canal de Potasio KCNQ2/química , Canal de Potasio KCNQ2/genética , Canal de Potasio KCNQ2/metabolismo , Canal de Potasio KCNQ3/química , Canal de Potasio KCNQ3/genética , Canal de Potasio KCNQ3/metabolismo , Simulación del Acoplamiento Molecular , Neurotransmisores , Triclosán/farmacología
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