1
|
Shore AN, Li K, Safari M, Qunies AM, Spitznagel BD, Weaver CD, Emmitte KA, Frankel WN, Weston MC. Heterozygous expression of a Kcnt1 gain-of-function variant has differential effects on SST- and PV-expressing cortical GABAergic neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.11.561953. [PMID: 37873369 PMCID: PMC10592778 DOI: 10.1101/2023.10.11.561953] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
More than twenty recurrent missense gain-of-function (GOF) mutations have been identified in the sodium-activated potassium (KNa) channel gene KCNT1 in patients with severe developmental and epileptic encephalopathies (DEEs), most of which are resistant to current therapies. Defining the neuron types most vulnerable to KCNT1 GOF will advance our understanding of disease mechanisms and provide refined targets for precision therapy efforts. Here, we assessed the effects of heterozygous expression of a Kcnt1 GOF variant (Y777H) on KNa currents and neuronal physiology among cortical glutamatergic and GABAergic neurons in mice, including those expressing vasoactive intestinal polypeptide (VIP), somatostatin (SST), and parvalbumin (PV), to identify and model the pathogenic mechanisms of autosomal dominant KCNT1 GOF variants in DEEs. Although the Kcnt1-Y777H variant had no effects on glutamatergic or VIP neuron function, it increased subthreshold KNa currents in both SST and PV neurons but with opposite effects on neuronal output; SST neurons became hypoexcitable with a higher rheobase current and lower action potential (AP) firing frequency, whereas PV neurons became hyperexcitable with a lower rheobase current and higher AP firing frequency. Further neurophysiological and computational modeling experiments showed that the differential effects of the Y777H variant on SST and PV neurons are not likely due to inherent differences in these neuron types, but to an increased persistent sodium current in PV, but not SST, neurons. The Y777H variant also increased excitatory input onto, and chemical and electrical synaptic connectivity between, SST neurons. Together, these data suggest differential pathogenic mechanisms, both direct and compensatory, contribute to disease phenotypes, and provide a salient example of how a pathogenic ion channel variant can cause opposite functional effects in closely related neuron subtypes due to interactions with other ionic conductances.
Collapse
Affiliation(s)
- Amy N. Shore
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
| | - Keyong Li
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
| | - Mona Safari
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Translational Biology, Medicine, and Health Graduate Program, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA
| | - Alshaima’a M. Qunies
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
- School of Biomedical Sciences, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Brittany D. Spitznagel
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN, USA
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Kyle A. Emmitte
- Department of Pharmaceutical Sciences, UNT System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX, USA
| | - Wayne N. Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY, USA
- Department of Neurology, Columbia University, New York, NY, USA
| | - Matthew C. Weston
- Fralin Biomedical Research Institute at Virginia Tech Carilion, Center for Neurobiology Research, Roanoke, VA, USA
- Department of Neurological Sciences, University of Vermont, Burlington, VT, USA
- Translational Biology, Medicine, and Health Graduate Program, Fralin Biomedical Research Institute at Virginia Tech Carilion, Roanoke, VA, USA
- School of Neuroscience, Virginia Tech, Blacksburg, VA, USA
| |
Collapse
|
2
|
Zhang Q, Ding R, Li Y, Qiao D, Kang J, Zong L, Li Y, Yuan Y, Jiao Y, Wang C, Yu Y, Zhang L, Li Y. Euchromatin histone-lysine N-methyltransferase 2 regulates the expression of potassium-sodium-activated channel subfamily T member 1 in primary sensory neurons and contributes to remifentanil-induced pain sensitivity. Brain Res Bull 2024; 212:110966. [PMID: 38670469 DOI: 10.1016/j.brainresbull.2024.110966] [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: 11/20/2023] [Revised: 04/17/2024] [Accepted: 04/22/2024] [Indexed: 04/28/2024]
Abstract
Intraoperative remifentanil administration has been linked to increased postoperative pain sensitivity. Recent studies have identified the involvement of euchromatic histone-lysine N-methyltransferase 2 (Ehmt2/G9a) in neuropathic pain associated with the transcriptional silencing of many potassium ion channel genes. This study investigates whether G9a regulates the potassium sodium-activated channel subfamily T member 1 (Slo2.2) in remifentanil-induced post-incisional hyperalgesia (RIH) in rodents. We performed remifentanil infusion (1 μg·kg-1·min-1 for 60 min) followed by plantar incision to induce RIH in rodents. Our results showed that RIH was accompanied by increased G9a and H3K9me2 production and decreased Slo2.2 expression 48 h postoperatively. Deletion of G9a rescued Slo2.2 expression in DRG and reduced RIH intensity. Slo2.2 overexpression also reversed this hyperalgesia phenotype. G9a overexpression decreased Slo2.2-mediated leak current and increased excitability in the small-diameter DRG neurons and laminal II small-diameter neurons in the spinal dorsal horn, which was implicated in peripheral and central sensitization. These results suggest that G9a contributes to the development of RIH by epigenetically silencing Slo2.2 in DRG neurons, leading to decreased central sensitization in the spinal cord. The findings may have implications for the development of novel therapeutic targets for the treatment of postoperative pain.
Collapse
Affiliation(s)
- Qiang Zhang
- Chu Hsien-I Memorial Hospital & Tianjin Institute of Endocrinology, Tianjin Medical University, Tianjin, China; Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Ran Ding
- Chinese Institute for Brain Research and Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Yuanjie Li
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Dan Qiao
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Jiamin Kang
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Linyue Zong
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yun Li
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yuan Yuan
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yang Jiao
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Chunyan Wang
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Yonghao Yu
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China
| | - Linlin Zhang
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China.
| | - Yize Li
- Tianjin Research Institute of Anesthesiology and Department of Anesthesiology, Tianjin Medical University General Hospital, Tianjin, China.
| |
Collapse
|
3
|
Iraci N, Carotenuto L, Ciaglia T, Belperio G, Di Matteo F, Mosca I, Carleo G, Giovanna Basilicata M, Ambrosino P, Turcio R, Puzo D, Pepe G, Gomez-Monterrey I, Soldovieri MV, Di Sarno V, Campiglia P, Miceli F, Bertamino A, Ostacolo C, Taglialatela M. In Silico Assisted Identification, Synthesis, and In Vitro Pharmacological Characterization of Potent and Selective Blockers of the Epilepsy-Associated KCNT1 Channel. J Med Chem 2024; 67:9124-9149. [PMID: 38782404 PMCID: PMC11181338 DOI: 10.1021/acs.jmedchem.4c00268] [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: 01/30/2024] [Revised: 03/28/2024] [Accepted: 04/09/2024] [Indexed: 05/25/2024]
Abstract
Gain-of-function (GoF) variants in KCNT1 channels cause severe, drug-resistant forms of epilepsy. Quinidine is a known KCNT1 blocker, but its clinical use is limited due to severe drawbacks. To identify novel KCNT1 blockers, a homology model of human KCNT1 was built and used to screen an in-house library of compounds. Among the 20 molecules selected, five (CPK4, 13, 16, 18, and 20) showed strong KCNT1-blocking ability in an in vitro fluorescence-based assay. Patch-clamp experiments confirmed a higher KCNT1-blocking potency of these compounds when compared to quinidine, and their selectivity for KCNT1 over hERG and Kv7.2 channels. Among identified molecules, CPK20 displayed the highest metabolic stability; this compound also blocked KCNT2 currents, although with a lower potency, and counteracted GoF effects prompted by 2 recurrent epilepsy-causing KCNT1 variants (G288S and A934T). The present results provide solid rational basis for future design of novel compounds to counteract KCNT1-related neurological disorders.
Collapse
Affiliation(s)
- Nunzio Iraci
- Department
of Chemical, Biological, Pharmaceutical and Environmental Sciences
(CHIBIOFARAM), University of Messina, Viale F. Stagno d’Alcontres
31, 98166 Messina, Italy
| | - Lidia Carotenuto
- Department
of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via S. Pansini, 5, 80131 Naples, Italy
| | - Tania Ciaglia
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Giorgio Belperio
- Department
of Science and Technology, University of
Sannio, Via F. De Sanctis, 82100 Benevento, Italy
| | - Francesca Di Matteo
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Ilaria Mosca
- Department
of Medicine and Health Science Vincenzo Tiberio, University of Molise, Via C. Gazzani, 86100 Campobasso, Italy
| | - Giusy Carleo
- Department
of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via S. Pansini, 5, 80131 Naples, Italy
| | - Manuela Giovanna Basilicata
- Department
of Advanced Medical and Surgical Sciences, University of Campania “Luigi Vanvitelli”, P.zza L. Miraglia 2, 80138 Naples, Italy
| | - Paolo Ambrosino
- Department
of Science and Technology, University of
Sannio, Via F. De Sanctis, 82100 Benevento, Italy
| | - Rita Turcio
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Deborah Puzo
- Department
of Medicine and Health Science Vincenzo Tiberio, University of Molise, Via C. Gazzani, 86100 Campobasso, Italy
| | - Giacomo Pepe
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Isabel Gomez-Monterrey
- Department
of Pharmacy, University Federico II of Naples, Via D. Montesano 49, 80131 Naples, Italy
| | - Maria Virginia Soldovieri
- Department
of Medicine and Health Science Vincenzo Tiberio, University of Molise, Via C. Gazzani, 86100 Campobasso, Italy
| | - Veronica Di Sarno
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Pietro Campiglia
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Francesco Miceli
- Department
of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via S. Pansini, 5, 80131 Naples, Italy
| | - Alessia Bertamino
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Carmine Ostacolo
- Department
of Pharmacy, University of Salerno, Via G. Paolo II 132, 84084 Fisciano, SA, Italy
| | - Maurizio Taglialatela
- Department
of Neuroscience, Reproductive Sciences and Dentistry, University Federico II of Naples, Via S. Pansini, 5, 80131 Naples, Italy
| |
Collapse
|
4
|
Balzulat A, Zhu WF, Flauaus C, Hernandez‐Olmos V, Heering J, Sethumadhavan S, Dubiel M, Frank A, Menge A, Hebchen M, Metzner K, Lu R, Lukowski R, Ruth P, Knapp S, Müller S, Steinhilber D, Hänelt I, Stark H, Proschak E, Schmidtko A. Discovery of a Small Molecule Activator of Slack (Kcnt1) Potassium Channels That Significantly Reduces Scratching in Mouse Models of Histamine-Independent and Chronic Itch. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2307237. [PMID: 38350720 PMCID: PMC11022729 DOI: 10.1002/advs.202307237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/15/2024] [Indexed: 02/15/2024]
Abstract
Various disorders are accompanied by histamine-independent itching, which is often resistant to the currently available therapies. Here, it is reported that the pharmacological activation of Slack (Kcnt1, KNa1.1), a potassium channel highly expressed in itch-sensitive sensory neurons, has therapeutic potential for the treatment of itching. Based on the Slack-activating antipsychotic drug, loxapine, a series of new derivatives with improved pharmacodynamic and pharmacokinetic profiles is designed that enables to validate Slack as a pharmacological target in vivo. One of these new Slack activators, compound 6, exhibits negligible dopamine D2 and D3 receptor binding, unlike loxapine. Notably, compound 6 displays potent on-target antipruritic activity in multiple mouse models of acute histamine-independent and chronic itch without motor side effects. These properties make compound 6 a lead molecule for the development of new antipruritic therapies targeting Slack.
Collapse
Affiliation(s)
- Annika Balzulat
- Institute of Pharmacology and Clinical PharmacyGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - W. Felix Zhu
- Institute of Pharmaceutical ChemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Cathrin Flauaus
- Institute of Pharmacology and Clinical PharmacyGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Victor Hernandez‐Olmos
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMPTheodor‐Stern‐Kai 760596Frankfurt am MainGermany
| | - Jan Heering
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMPTheodor‐Stern‐Kai 760596Frankfurt am MainGermany
| | - Sunesh Sethumadhavan
- Institute of BiochemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Mariam Dubiel
- Institute of Pharmaceutical and Medicinal ChemistryHeinrich Heine University DüsseldorfUniversitätsstr. 140225DüsseldorfGermany
| | - Annika Frank
- Institute of Pharmaceutical and Medicinal ChemistryHeinrich Heine University DüsseldorfUniversitätsstr. 140225DüsseldorfGermany
| | - Amelie Menge
- Institute of Pharmaceutical ChemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
- Structural Genomics Consortium (SGC)Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtMax‐von‐Laue‐Str. 1560438Frankfurt am MainGermany
| | - Maureen Hebchen
- Institute of Pharmacology and Clinical PharmacyGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Katharina Metzner
- Institute of Pharmacology and Clinical PharmacyGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Ruirui Lu
- Institute of Pharmacology and Clinical PharmacyGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Robert Lukowski
- Department of PharmacologyToxicology and Clinical PharmacyInstitute of Pharmacy University of TübingenAuf der Morgenstelle 872076TübingenGermany
| | - Peter Ruth
- Department of PharmacologyToxicology and Clinical PharmacyInstitute of Pharmacy University of TübingenAuf der Morgenstelle 872076TübingenGermany
| | - Stefan Knapp
- Institute of Pharmaceutical ChemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
- Structural Genomics Consortium (SGC)Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtMax‐von‐Laue‐Str. 1560438Frankfurt am MainGermany
| | - Susanne Müller
- Institute of Pharmaceutical ChemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
- Structural Genomics Consortium (SGC)Buchmann Institute for Molecular Life SciencesGoethe University FrankfurtMax‐von‐Laue‐Str. 1560438Frankfurt am MainGermany
| | - Dieter Steinhilber
- Institute of Pharmaceutical ChemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMPTheodor‐Stern‐Kai 760596Frankfurt am MainGermany
| | - Inga Hänelt
- Institute of BiochemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| | - Holger Stark
- Institute of Pharmaceutical and Medicinal ChemistryHeinrich Heine University DüsseldorfUniversitätsstr. 140225DüsseldorfGermany
| | - Ewgenij Proschak
- Institute of Pharmaceutical ChemistryGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
- Fraunhofer Institute for Translational Medicine and Pharmacology ITMPTheodor‐Stern‐Kai 760596Frankfurt am MainGermany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical PharmacyGoethe University FrankfurtMax‐von‐Laue‐Str. 960438Frankfurt am MainGermany
| |
Collapse
|
5
|
Malone TJ, Wu J, Zhang Y, Licznerski P, Chen R, Nahiyan S, Pedram M, Jonas EA, Kaczmarek LK. Neuronal potassium channel activity triggers initiation of mRNA translation through binding of translation regulators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.07.579306. [PMID: 38370631 PMCID: PMC10871293 DOI: 10.1101/2024.02.07.579306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Neuronal activity stimulates mRNA translation crucial for learning and development. While FMRP (Fragile X Mental Retardation Protein) and CYFIP1 (Cytoplasmic FMR1 Interacting Protein 1) regulate translation, the mechanism linking translation to neuronal activity is not understood. We now find that translation is stimulated when FMRP and CYFIP1 translocate to the potassium channel Slack (KCNT1, Slo2.2). When Slack is activated, both factors are released from eIF4E (Eukaryotic Initiation Factor 4E), where they normally inhibit translation initiation. A constitutively active Slack mutation and pharmacological stimulation of the wild-type channel both increase binding of FMRP and CYFIP1 to the channel, enhancing the translation of a reporter for β-actin mRNA in cell lines and the synthesis of β-actin in neuronal dendrites. Slack activity-dependent translation is abolished when both FMRP and CYFIP1 expression are suppressed. The effects of Slack mutations on activity-dependent translation may explain the severe intellectual disability produced by these mutations in humans. HIGHLIGHTS Activation of Slack channels triggers translocation of the FMRP/CYFIP1 complexSlack channel activation regulates translation initiation of a β-actin reporter constructA Slack gain-of-function mutation increases translation of β-actin reporter construct and endogenous cortical β-actinFMRP and CYFIP1 are required for Slack activity-dependent translation. IN BRIEF Malone et al . show that the activation of Slack channels triggers translocation of the FMRP/CYFIP1 complex from the translation initiation factor eIF4E to the channel. This translocation releases eIF4E and stimulates mRNA translation of a reporter for β-actin and cortical β-actin mRNA, elucidating the mechanism that connects neuronal activity with translational regulation.
Collapse
|
6
|
Hill SF, Jafar-Nejad P, Rigo F, Meisler MH. Reduction of Kcnt1 is therapeutic in mouse models of SCN1A and SCN8A epilepsy. Front Neurosci 2023; 17:1282201. [PMID: 37901435 PMCID: PMC10603267 DOI: 10.3389/fnins.2023.1282201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 09/25/2023] [Indexed: 10/31/2023] Open
Abstract
Developmental and epileptic encephalopathies (DEEs) are severe seizure disorders with inadequate treatment options. Gain- or loss-of-function mutations of neuronal ion channel genes, including potassium channels and voltage-gated sodium channels, are common causes of DEE. We previously demonstrated that reduced expression of the sodium channel gene Scn8a is therapeutic in mouse models of sodium and potassium channel mutations. In the current study, we tested whether reducing expression of the potassium channel gene Kcnt1 would be therapeutic in mice with mutation of the sodium channel genes Scn1a or Scn8a. A Kcnt1 antisense oligonucleotide (ASO) prolonged survival of both Scn1a and Scn8a mutant mice, suggesting a modulatory effect for KCNT1 on the balance between excitation and inhibition. The cation channel blocker quinidine was not effective in prolonging survival of the Scn8a mutant. Our results implicate KCNT1 as a therapeutic target for treatment of SCN1A and SCN8A epilepsy.
Collapse
Affiliation(s)
- Sophie F. Hill
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
| | | | - Frank Rigo
- Ionis Pharmaceuticals, Carlsbad, CA, United States
| | - Miriam H. Meisler
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, United States
- Department of Human Genetics, University of Michigan, Ann Arbor, MI, United States
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States
| |
Collapse
|
7
|
Skrabak D, Bischof H, Pham T, Ruth P, Ehinger R, Matt L, Lukowski R. Slack K + channels limit kainic acid-induced seizure severity in mice by modulating neuronal excitability and firing. Commun Biol 2023; 6:1029. [PMID: 37821582 PMCID: PMC10567740 DOI: 10.1038/s42003-023-05387-9] [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: 03/16/2023] [Accepted: 09/25/2023] [Indexed: 10/13/2023] Open
Abstract
Mutations of the Na+-activated K+ channel Slack (KCNT1) are associated with terrible epilepsy syndromes that already begin in infancy. Here we report increased severity of acute kainic acid-induced seizures in adult and juvenile Slack knockout mice (Slack-/-) in vivo. Fittingly, we find exacerbation of cell death following kainic acid exposure in organotypic hippocampal slices as well as dissociated hippocampal cultures from Slack-/- in vitro. Furthermore, in cultured Slack-/- neurons, kainic acid-triggered Ca2+ influx and K+ efflux as well as depolarization-induced tetrodotoxin-sensitive inward currents are higher compared to the respective controls. This apparent changes in ion homeostasis could possibly explain altered action potential kinetics of Slack-/- neurons: steeper rise slope, decreased threshold, and duration of afterhyperpolarization, which ultimately lead to higher action potential frequencies during kainic acid application or injection of depolarizing currents. Based on our data, we propose Slack as crucial gatekeeper of neuronal excitability to acutely limit seizure severity.
Collapse
Affiliation(s)
- David Skrabak
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Helmut Bischof
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Thomas Pham
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Rebekka Ehinger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Lucas Matt
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany.
| |
Collapse
|
8
|
Barry AM, Zhao N, Yang X, Bennett DL, Baskozos G. Deep RNA-seq of male and female murine sensory neuron subtypes after nerve injury. Pain 2023; 164:2196-2215. [PMID: 37318015 PMCID: PMC10502896 DOI: 10.1097/j.pain.0000000000002934] [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: 12/16/2022] [Revised: 01/27/2023] [Accepted: 02/05/2023] [Indexed: 06/16/2023]
Abstract
ABSTRACT Dorsal root ganglia (DRG) neurons have been well described for their role in driving both acute and chronic pain. Although nerve injury is known to cause transcriptional dysregulation, how this differs across neuronal subtypes and the impact of sex is unclear. Here, we study the deep transcriptional profiles of multiple murine DRG populations in early and late pain states while considering sex. We have exploited currently available transgenics to label numerous subpopulations for fluorescent-activated cell sorting and subsequent transcriptomic analysis. Using bulk tissue samples, we are able to circumvent the issues of low transcript coverage and drop-outs seen with single-cell data sets. This increases our power to detect novel and even subtle changes in gene expression within neuronal subtypes and discuss sexual dimorphism at the neuronal subtype level. We have curated this resource into an accessible database for other researchers ( https://livedataoxford.shinyapps.io/drg-directory/ ). We see both stereotyped and unique subtype signatures in injured states after nerve injury at both an early and late timepoint. Although all populations contribute to a general injury signature, subtype enrichment changes can also be seen. Within populations, there is not a strong intersection of sex and injury, but previously unknown sex differences in naïve states-particularly in Aβ-RA + Aδ-low threshold mechanoreceptors-still contribute to differences in injured neurons.
Collapse
Affiliation(s)
- Allison M. Barry
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Na Zhao
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Xun Yang
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - David L. Bennett
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| | - Georgios Baskozos
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
9
|
Zhang J, Liu S, Fan J, Yan R, Huang B, Zhou F, Yuan T, Gong J, Huang Z, Jiang D. Structural basis of human Slo2.2 channel gating and modulation. Cell Rep 2023; 42:112858. [PMID: 37494189 DOI: 10.1016/j.celrep.2023.112858] [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: 12/15/2022] [Revised: 06/16/2023] [Accepted: 07/07/2023] [Indexed: 07/28/2023] Open
Abstract
The sodium-activated Slo2.2 channel is abundantly expressed in the brain, playing a critical role in regulating neuronal excitability. The Na+-binding site and the underlying mechanisms of Na+-dependent activation remain unclear. Here, we present cryoelectron microscopy (cryo-EM) structures of human Slo2.2 in closed, open, and inhibitor-bound form at resolutions of 2.6-3.2 Å, revealing gating mechanisms of Slo2.2 regulation by cations and a potent inhibitor. The cytoplasmic gating ring domain of the closed Slo2.2 harbors multiple K+ and Zn2+ sites, which stabilize the channel in the closed conformation. The open Slo2.2 structure reveals at least two Na+-sensitive sites where Na+ binding induces expansion and rotation of the gating ring that opens the inner gate. Furthermore, a potent inhibitor wedges into a pocket formed by pore helix and S6 helix and blocks the pore. Together, our results provide a comprehensive structural framework for the investigation of Slo2.2 channel gating, Na+ sensation, and inhibition.
Collapse
Affiliation(s)
- Jiangtao Zhang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Shiqi Liu
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Junping Fan
- Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Department of Chemical Biology, College of Chemistry and Molecular Engineering, Synthetic and Functional Biomolecules Center, and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, China
| | - Rui Yan
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Bo Huang
- Beijing StoneWise Technology Co Ltd., Haidian District, Beijing, China
| | - Feng Zhou
- Beijing StoneWise Technology Co Ltd., Haidian District, Beijing, China
| | - Tian Yuan
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Jianke Gong
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Zhuo Huang
- State Key Laboratory of Natural and Biomimetic Drugs, Department of Molecular and Cellular Pharmacology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China; IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China.
| | - Daohua Jiang
- Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; University of Chinese Academy of Sciences, Beijing 100049, China.
| |
Collapse
|
10
|
Frutos-Rincón L, Luna C, Aleixandre-Carrera F, Velasco E, Diaz-Tahoces A, Meseguer V, Gallar J, Acosta MC. The Contribution of TRPA1 to Corneal Thermosensitivity and Blink Regulation in Young and Aged Mice. Int J Mol Sci 2023; 24:12620. [PMID: 37628800 PMCID: PMC10454529 DOI: 10.3390/ijms241612620] [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: 06/22/2023] [Revised: 07/31/2023] [Accepted: 08/04/2023] [Indexed: 08/27/2023] Open
Abstract
The role of TRPA1 in the thermosensitivity of the corneal cold thermoreceptor nerve endings was studied in young and aged mice. The contribution of the TRPA1-dependent activity to basal tearing and thermally-evoked blink was also explored. The corneal cold thermoreceptors' activity was recorded extracellularly in young (5-month-old) and aged (18-month-old) C57BL/6WT (WT) and TRPA1-/- knockout (TRPA1-KO) mice at basal temperature (34 °C) and during cooling (15 °C) and heating (45 °C) ramps. The blink response to cold and heat stimulation of the ocular surface and the basal tearing rate were also measured in young animals using orbicularis oculi muscle electromyography (OOemg) and phenol red threads, respectively. The background activity at 34 °C and the cooling- and heating-evoked responses of the cold thermoreceptors were similar in WT and TRPA1-KO animals, no matter the age. Similar to the aged WT mice, in the young and aged TRPA1-KO mice, most of the cold thermoreceptors presented low frequency background activity, a low cooling threshold, and a sluggish response to heating. The amplitude and duration of the OOemg signals correlated with the magnitude of the induced thermal change in the WT but not in the TRPA1-KO mice. The basal tearing was similar in the TRPA1-KO and WT mice. The electrophysiological data suggest that the TRPA1-dependent nerve activity, which declines with age, contributes to detecting the warming of the ocular surface and also to integrating the thermally-evoked reflex blink.
Collapse
Affiliation(s)
- Laura Frutos-Rincón
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Carolina Luna
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Fernando Aleixandre-Carrera
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Enrique Velasco
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Ariadna Diaz-Tahoces
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Víctor Meseguer
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| | - Juana Gallar
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
- Instituto de Investigación Biomédica y Sanitaria de Alicante, 03010 Alicante, Spain
| | - M. Carmen Acosta
- Instituto de Neurociencias, Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas, 03550 San Juan de Alicante, Spain; (L.F.-R.); (C.L.); (F.A.-C.); (E.V.); (A.D.-T.); (V.M.); (J.G.)
| |
Collapse
|
11
|
Xu J, Lv YT, Zhao XY, Wang JJ, Shen ZS, Li J, Zhang FF, Liu J, Wang XH, Xu Y, Geng Q, Ding YT, Xu JJ, Tan MJ, Li ZX, Wang R, Chen J, Sun W, Cui M, Logothetis DE, Cao JL, Tang QY, Zhang Z. Identification of Sodium- and Chloride-Sensitive Sites in the Slack Channel. J Neurosci 2023; 43:2665-2681. [PMID: 36898835 PMCID: PMC10089238 DOI: 10.1523/jneurosci.1365-22.2023] [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: 07/12/2022] [Revised: 02/24/2023] [Accepted: 02/28/2023] [Indexed: 03/12/2023] Open
Abstract
The Slack channel (KCNT1, Slo2.2) is a sodium-activated and chloride-activated potassium channel that regulates heart rate and maintains the normal excitability of the nervous system. Despite intense interest in the sodium gating mechanism, a comprehensive investigation to identify the sodium-sensitive and chloride-sensitive sites has been missing. In the present study, we identified two potential sodium-binding sites in the C-terminal domain of the rat Slack channel by conducting electrophysical recordings and systematic mutagenesis of cytosolic acidic residues in the rat Slack channel C terminus. In particular, by taking advantage of the M335A mutant, which results in the opening of the Slack channel in the absence of cytosolic sodium, we found that among the 92 screened negatively charged amino acids, E373 mutants could completely remove sodium sensitivity of the Slack channel. In contrast, several other mutants showed dramatic decreases in sodium sensitivity but did not abolish it altogether. Furthermore, molecular dynamics (MD) simulations performed at the hundreds of nanoseconds timescale revealed one or two sodium ions at the E373 position or an acidic pocket composed of several negatively charged residues. Moreover, the MD simulations predicted possible chloride interaction sites. By screening predicted positively charged residues, we identified R379 as a chloride interaction site. Thus, we conclude that the E373 site and the D863/E865 pocket are two potential sodium-sensitive sites, while R379 is a chloride interaction site in the Slack channel.SIGNIFICANCE STATEMENT The research presented here identified two distinct sodium and one chloride interaction sites located in the intracellular C-terminal domain of the Slack (Slo2.2, KCNT1) channel. Identification of the sites responsible for the sodium and chloride activation of the Slack channel sets its gating property apart from other potassium channels in the BK channel family. This finding sets the stage for future functional and pharmacological studies of this channel.
Collapse
Affiliation(s)
- Jie Xu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Yan-Tian Lv
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Xiao-Yun Zhao
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Jing-Jing Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Zhong-Shan Shen
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Jian Li
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Fei-Fei Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Jing Liu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Xiao-Hui Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Yun Xu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Qi Geng
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Yi-Tong Ding
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Jing-Jing Xu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Meng-Jiao Tan
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Zhi-Xiao Li
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Ran Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Jian Chen
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Wen Sun
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts 02115
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts 02115
| | - Jun-Li Cao
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Qiong-Yao Tang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| | - Zhe Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou 221004, People's Republic of China
| |
Collapse
|
12
|
Miziak B, Czuczwar SJ. Approaches for the discovery of drugs that target K Na 1.1 channels in KCNT1-associated epilepsy. Expert Opin Drug Discov 2022; 17:1313-1328. [PMID: 36408599 DOI: 10.1080/17460441.2023.2150164] [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]
Abstract
INTRODUCTION There are approximately 70 million people with epilepsy and about 30% of patients are not satisfactorily treated. A link between gene mutations and epilepsy is well documented. A number of pathological variants of KCNT1 gene (encoding the weakly voltage-dependent sodium-activated potassium channel - KNa 1.1) mutations has been found. For instance, epilepsy of infancy with migrating focal seizures, autosomal sleep-related hypermotor epilepsy or Ohtahara syndrome have been associated with KCNT1 gene mutations. AREAS COVERED Several methods for studies on KNa 1.1 channels have been reviewed - patch clamp analysis, Förster resonance energy transfer spectroscopy and whole-exome sequencing. The authors also review available drugs for the management of KCNT1 epilepsies. EXPERT OPINION The current methods enable deeper insights into electrophysiology of KNa 1.1 channels or its functioning in different activation states. It is also possible to identify a given KCNT1 mutation. Quinidine and cannabidiol show variable efficacy as add-on to baseline antiepileptic drugs so more effective treatments are required. A combined approach with the methods shown above, in silico methods and the animal model of KCNT1 epilepsies seems likely to create personalized treatment of patients with KCNT1 gene mutations.
Collapse
Affiliation(s)
- Barbara Miziak
- Department of Pathophysiology, Medical University of Lublin, Lublin, Poland
| | | |
Collapse
|
13
|
Nuss P, Corruble E, Baloche E, Garay R, Llorca PM. Fifty years of experience with loxapine for the rapid non-coercive tranquilization of acute behavioral disturbances in schizophrenia patients, and beyond. Expert Rev Neurother 2022; 22:639-653. [PMID: 35913401 DOI: 10.1080/14737175.2022.2108706] [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: 11/04/2022]
Abstract
INTRODUCTION Acute behavioral disturbances in psychosis, including agitation, comprise a heterogeneous group of manifestations varying in intensity and duration they last for. They require rapid, non-coercive treatments ranging from verbal de-escalation to the calming effect of pharmacological agents. The treatment goals are reduction of patient suffering and prevention of disease deterioration. Stabilizing rather than sedating is preferred to ensure improved compliance and a stronger therapeutic alliance. Furthermore, animal pharmacology and clinical studies on agitation reveal the robust calming and anxiolytic properties of loxapine. AREAS COVERED This review covers the pharmacological and clinical history of loxapine along with research developments. It emphasizes the advantages of its multiple formulations ranging from injectable forms and tablets to orally inhaled forms to attain rapid and fine-tuned tranquilization. EXPERT OPINION Rapid tranquillization is achieved within 2-6 hours using liquid orally-consumed loxapine, and within an hour or less with its IM or orally inhaled forms. Loxapine has been adopted in the management of a wide range of acute disturbances, such as agitation in psychosis. In the context of personalized medicine, key cellular and molecular elements of the schizophrenia phenotype were recently shown to be improved with loxapine.
Collapse
Affiliation(s)
- Philippe Nuss
- Department of Adult Psychiatry and Medical Psychology, Sorbonne University, Saint-Antoine Hospital, Paris, France & Inserm UMR-S938, Saint-Antoine Research Centre, Sorbonne University, Paris, France
| | - Emmanuelle Corruble
- INSERM CESP-Team 'Moods', Paris-Saclay University & Department of Psychiatry, Bicetre Hospital & School of Medicine Paris-Saclay, Le Kremlin Bicetre, France
| | | | - Ricardo Garay
- Department of Pharmacology and Therapeutics, Craven, France; CNRS, National Centre of Scientific Research, Paris, France
| | | |
Collapse
|
14
|
Zhou F, Metzner K, Engel P, Balzulat A, Sisignano M, Ruth P, Lukowski R, Schmidtko A, Lu R. Slack Potassium Channels Modulate TRPA1-Mediated Nociception in Sensory Neurons. Cells 2022; 11:cells11101693. [PMID: 35626730 PMCID: PMC9140117 DOI: 10.3390/cells11101693] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/15/2022] [Accepted: 05/17/2022] [Indexed: 12/13/2022] Open
Abstract
The transient receptor potential (TRP) ankyrin type 1 (TRPA1) channel is highly expressed in a subset of sensory neurons where it acts as an essential detector of painful stimuli. However, the mechanisms that control the activity of sensory neurons upon TRPA1 activation remain poorly understood. Here, using in situ hybridization and immunostaining, we found TRPA1 to be extensively co-localized with the potassium channel Slack (KNa1.1, Slo2.2, or Kcnt1) in sensory neurons. Mice lacking Slack globally (Slack−/−) or conditionally in sensory neurons (SNS-Slack−/−) demonstrated increased pain behavior after intraplantar injection of the TRPA1 activator allyl isothiocyanate. By contrast, pain behavior induced by the TRP vanilloid 1 (TRPV1) activator capsaicin was normal in Slack-deficient mice. Patch-clamp recordings in sensory neurons and in a HEK cell line transfected with TRPA1 and Slack revealed that Slack-dependent potassium currents (IKS) are modulated in a TRPA1-dependent manner. Taken together, our findings highlight Slack as a modulator of TRPA1-mediated, but not TRPV1-mediated, activation of sensory neurons.
Collapse
Affiliation(s)
- Fangyuan Zhou
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, 60438 Frankfurt am Main, Germany; (F.Z.); (K.M.); (P.E.); (A.B.); (A.S.)
| | - Katharina Metzner
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, 60438 Frankfurt am Main, Germany; (F.Z.); (K.M.); (P.E.); (A.B.); (A.S.)
| | - Patrick Engel
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, 60438 Frankfurt am Main, Germany; (F.Z.); (K.M.); (P.E.); (A.B.); (A.S.)
| | - Annika Balzulat
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, 60438 Frankfurt am Main, Germany; (F.Z.); (K.M.); (P.E.); (A.B.); (A.S.)
| | - Marco Sisignano
- Institute of Clinical Pharmacology, Pharmazentrum Frankfurt/ZAFES, Goethe University, 60590 Frankfurt am Main, Germany;
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Tübingen, 72076 Tübingen, Germany; (P.R.); (R.L.)
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, University of Tübingen, 72076 Tübingen, Germany; (P.R.); (R.L.)
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, 60438 Frankfurt am Main, Germany; (F.Z.); (K.M.); (P.E.); (A.B.); (A.S.)
| | - Ruirui Lu
- Institute of Pharmacology and Clinical Pharmacy, Goethe University, 60438 Frankfurt am Main, Germany; (F.Z.); (K.M.); (P.E.); (A.B.); (A.S.)
- Correspondence: ; Tel.: +49-69-798-29377
| |
Collapse
|
15
|
Slick Potassium Channels Control Pain and Itch in Distinct Populations of Sensory and Spinal Neurons in Mice. Anesthesiology 2022; 136:802-822. [PMID: 35303056 DOI: 10.1097/aln.0000000000004163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Slick, a sodium-activated potassium channel, has been recently identified in somatosensory pathways, but its functional role is poorly understood. The authors of this study hypothesized that Slick is involved in processing sensations of pain and itch. METHODS Immunostaining, in situ hybridization, Western blot, and real-time quantitative reverse transcription polymerase chain reaction were used to investigate the expression of Slick in dorsal root ganglia and the spinal cord. Mice lacking Slick globally (Slick-/-) or conditionally in neurons of the spinal dorsal horn (Lbx1-Slick-/-) were assessed in behavioral models. RESULTS The authors found Slick to be enriched in nociceptive Aδ-fibers and in populations of interneurons in the spinal dorsal horn. Slick-/- mice, but not Lbx1-Slick-/- mice, showed enhanced responses to noxious heat in the hot plate and tail-immersion tests. Both Slick-/- and Lbx1-Slick-/- mice demonstrated prolonged paw licking after capsaicin injection (mean ± SD, 45.6 ± 30.1 s [95% CI, 19.8 to 71.4]; and 13.1 ± 16.1 s [95% CI, 1.8 to 28.0]; P = 0.006 [Slick-/- {n = 8} and wild-type {n = 7}, respectively]), which was paralleled by increased phosphorylation of the neuronal activity marker extracellular signal-regulated kinase in the spinal cord. In the spinal dorsal horn, Slick is colocalized with somatostatin receptor 2 (SSTR2), and intrathecal preadministration of the SSTR2 antagonist CYN-154806 prevented increased capsaicin-induced licking in Slick-/- and Lbx1-Slick-/- mice. Moreover, scratching after intrathecal delivery of the somatostatin analog octreotide was considerably reduced in Slick-/- and Lbx1-Slick-/- mice (Slick-/- [n = 8]: 6.1 ± 6.7 bouts [95% CI, 0.6 to 11.7]; wild-type [n =8]: 47.4 ± 51.1 bouts [95% CI, 4.8 to 90.2]; P = 0.039). CONCLUSIONS Slick expressed in a subset of sensory neurons modulates heat-induced pain, while Slick expressed in spinal cord interneurons inhibits capsaicin-induced pain but facilitates somatostatin-induced itch. EDITOR’S PERSPECTIVE
Collapse
|
16
|
Liu Y, Zhang FF, Song Y, Wang R, Zhang Q, Shen ZS, Zhang FF, Zhong DY, Wang XH, Guo Q, Tang QY, Zhang Z. The Slack Channel Deletion Causes Mechanical Pain Hypersensitivity in Mice. Front Mol Neurosci 2022; 15:811441. [PMID: 35359569 PMCID: PMC8963359 DOI: 10.3389/fnmol.2022.811441] [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: 11/08/2021] [Accepted: 02/08/2022] [Indexed: 11/13/2022] Open
Abstract
The role of the Slack (also known as Slo2.2, KNa1.1, or KCNT1) channel in pain-sensing is still in debate on which kind of pain it regulates. In the present study, we found that the Slack–/– mice exhibited decreased mechanical pain threshold but normal heat and cold pain sensitivity. Subsequently, X-gal staining, in situ hybridization, and immunofluorescence staining revealed high expression of the Slack channel in Isolectin B4 positive (IB4+) neurons in the dorsal root ganglion (DRG) and somatostatin-positive (SOM+) neurons in the spinal cord. Patch-clamp recordings indicated the firing frequency was increased in both small neurons in DRG and spinal SOM+ neurons in the Slack–/– mice whereas no obvious slow afterhyperpolarization was observed in both WT mice and Slack–/– mice. Furthermore, we found Kcnt1 gene expression in spinal SOM+ neurons in Slack–/– mice partially relieved the mechanical pain hypersensitivity of Slack–/– mice and decreased AP firing rates of the spinal SOM+ neurons. Finally, deletion of the Slack channel in spinal SOM+ neurons is sufficient to result in mechanical pain hypersensitivity in mice. In summary, our results suggest the important role of the Slack channel in the regulation of mechanical pain-sensing both in small neurons in DRG and SOM+ neurons in the spinal dorsal horn.
Collapse
Affiliation(s)
- Ye Liu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Fang-Fang Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Ying Song
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Ran Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Qi Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Zhong-Shan Shen
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Fei-Fei Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Dan-Ya Zhong
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Xiao-Hui Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Qing Guo
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
| | - Qiong-Yao Tang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
- *Correspondence: Qiong-Yao Tang,
| | - Zhe Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
- NMPA Key Laboratory for Research and Evaluation of Narcotic and Psychotropic Drugs, Xuzhou Medical University, Xuzhou, China
- Zhe Zhang,
| |
Collapse
|
17
|
Zhang Q, Liu Y, Xu J, Teng Y, Zhang Z. The Functional Properties, Physiological Roles, Channelopathy and Pharmacological Characteristics of the Slack (KCNT1) Channel. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1349:387-400. [PMID: 35138624 DOI: 10.1007/978-981-16-4254-8_18] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The KCNT1 gene encodes the sodium-activated potassium channel that is abundantly expressed in the central nervous system of mammalians and plays an important role in reducing neuronal excitability. Structurally, the KCNT1 channel is absent of voltage sensor but possesses a long C-terminus including RCK1 and RCK2domain, to which the intracellular sodium and chloride bind to activate the channel. Recent publications using electron cryo-microscopy (cryo-EM) revealed the open and closed structural characteristics of the KCNT1 channel and co-assembly of functional domains. The activation of the KCNT1 channel regulates various physiological processes including nociceptive behavior, itch, spatial learning. Meanwhile, malfunction of this channel causes important pathophysiological consequences, including Fragile X syndrome and a wide spectrum of seizure disorders. This review comprehensively describes the structure, expression patterns, physiological functions of the KCNT1 channel and emphasizes the channelopathy of gain-of-function KCNT1 mutations in epilepsy.
Collapse
Affiliation(s)
- Qi Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Ye Liu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Jie Xu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Yue Teng
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China
| | - Zhe Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China.
- Jiangsu Province Key Laboratory of Anesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, Jiangsu Province, China.
| |
Collapse
|
18
|
Slo2/K Na Channels in Drosophila Protect against Spontaneous and Induced Seizure-like Behavior Associated with an Increased Persistent Na + Current. J Neurosci 2021; 41:9047-9063. [PMID: 34544836 DOI: 10.1523/jneurosci.0290-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/20/2021] [Accepted: 09/13/2021] [Indexed: 11/21/2022] Open
Abstract
Na+ sensitivity is a unique feature of Na+-activated K+ (KNa) channels, making them naturally suited to counter a sudden influx in Na+ ions. As such, it has long been suggested that KNa channels may serve a protective function against excessive excitation associated with neuronal injury and disease. This hypothesis, however, has remained largely untested. Here, we examine KNa channels encoded by the Drosophila Slo2 (dSlo2) gene in males and females. We show that dSlo2/KNa channels are selectively expressed in cholinergic neurons in the adult brain, as well as in glutamatergic motor neurons, where dampening excitation may function to inhibit global hyperactivity and seizure-like behavior. Indeed, we show that effects of feeding Drosophila a cholinergic agonist are exacerbated by the loss of dSlo2/KNa channels. Similar to mammalian Slo2/KNa channels, we show that dSlo2/KNa channels encode a TTX-sensitive K+ conductance, indicating that dSlo2/KNa channels can be activated by Na+ carried by voltage-dependent Na+ channels. We then tested the role of dSlo2/KNa channels in established genetic seizure models in which the voltage-dependent persistent Na+ current (INap) is elevated. We show that the absence of dSlo2/KNa channels increased susceptibility to mechanically induced seizure-like behavior. Similar results were observed in WT flies treated with veratridine, an enhancer of INap Finally, we show that loss of dSlo2/KNa channels in both genetic and pharmacologically primed seizure models resulted in the appearance of spontaneous seizures. Together, our results support a model in which dSlo2/KNa channels, activated by neuronal overexcitation, contribute to a protective threshold to suppress the induction of seizure-like activity.SIGNIFICANCE STATEMENT Slo2/KNa channels are unique in that they constitute a repolarizing K+ pore that is activated by the depolarizing Na+ ion, making them naturally suited to function as a protective "brake" against overexcitation and Na+ overload. Here, we test this hypothesis in vivo by examining how a null mutation of the Drosophila Slo2 (dSlo2)/KNa gene affects seizure-like behavior in genetic and pharmacological models of epilepsy. We show that indeed the loss of dSlo2/KNa channels results in increased incidence and severity of induced seizure behavior, as well as the appearance of spontaneous seizure activity. Our results advance our understanding of neuronal excitability and protective mechanisms that preserve normal physiology and the suppression of seizure susceptibility.
Collapse
|
19
|
Ehinger R, Kuret A, Matt L, Frank N, Wild K, Kabagema-Bilan C, Bischof H, Malli R, Ruth P, Bausch AE, Lukowski R. Slack K + channels attenuate NMDA-induced excitotoxic brain damage and neuronal cell death. FASEB J 2021; 35:e21568. [PMID: 33817875 DOI: 10.1096/fj.202002308rr] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 03/14/2021] [Accepted: 03/17/2021] [Indexed: 12/13/2022]
Abstract
The neuronal Na+ -activated K+ channel Slack (aka Slo2.2, KNa 1.1, or Kcnt1) has been implicated in setting and maintaining the resting membrane potential and defining excitability and firing patterns, as well as in the generation of the slow afterhyperpolarization following bursts of action potentials. Slack activity increases significantly under conditions of high intracellular Na+ levels, suggesting this channel may exert important pathophysiological functions. To address these putative roles, we studied whether Slack K+ channels contribute to pathological changes and excitotoxic cell death caused by glutamatergic overstimulation of Ca2+ - and Na+ -permeable N-methyl-D-aspartic acid receptors (NMDAR). Slack-deficient (Slack KO) and wild-type (WT) mice were subjected to intrastriatal microinjections of the NMDAR agonist NMDA. NMDA-induced brain lesions were significantly increased in Slack KO vs WT mice, suggesting that the lack of Slack renders neurons particularly susceptible to excitotoxicity. Accordingly, excessive neuronal cell death was seen in Slack-deficient primary cerebellar granule cell (CGC) cultures exposed to glutamate and NMDA. Differences in neuronal survival between WT and Slack KO CGCs were largely abolished by the NMDAR antagonist MK-801, but not by NBQX, a potent and highly selective competitive antagonist of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type ionotropic glutamate receptors. Interestingly, NMDAR-evoked Ca2+ signals did not differ with regard to Slack genotype in CGCs. However, real-time monitoring of K+ following NMDAR activation revealed a significant contribution of this channel to the intracellular drop in K+ . Finally, TrkB and TrkC neurotrophin receptor transcript levels were elevated in NMDA-exposed Slack-proficient CGCs, suggesting a mechanism by which this K+ channel contributes to the activation of the extracellular-signal-regulated kinase (Erk) pathway and thereby to neuroprotection. Combined, our findings suggest that Slack-dependent K+ signals oppose the NMDAR-mediated excitotoxic neuronal injury by promoting pro-survival signaling via the BDNF/TrkB and Erk axis.
Collapse
Affiliation(s)
- Rebekka Ehinger
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Anna Kuret
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Lucas Matt
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Nadine Frank
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Katharina Wild
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Clement Kabagema-Bilan
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Helmut Bischof
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Roland Malli
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Peter Ruth
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Anne E Bausch
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| | - Robert Lukowski
- Department of Pharmacology, Toxicology and Clinical Pharmacy, Institute of Pharmacy, University of Tübingen, Tübingen, Germany
| |
Collapse
|
20
|
Metzner K, Gross T, Balzulat A, Wack G, Lu R, Schmidtko A. Lack of efficacy of a partial adenosine A1 receptor agonist in neuropathic pain models in mice. Purinergic Signal 2021; 17:503-514. [PMID: 34313915 PMCID: PMC8410902 DOI: 10.1007/s11302-021-09806-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2020] [Accepted: 06/28/2021] [Indexed: 12/25/2022] Open
Abstract
Previous studies suggest that adenosine A1 receptors (A1R) modulate the processing of pain. The aim of this study was to characterize the distribution of A1R in nociceptive tissues and to evaluate whether targeting A1R with the partial agonist capadenoson may reduce neuropathic pain in mice. The cellular distribution of A1R in dorsal root ganglia (DRG) and the spinal cord was analyzed using fluorescent in situ hybridization. In behavioral experiments, neuropathic pain was induced by spared nerve injury or intraperitoneal injection of paclitaxel, and tactile hypersensitivities were determined using a dynamic plantar aesthesiometer. Whole-cell patch-clamp recordings were performed to assess electrophysiological properties of dissociated DRG neurons. We found A1R to be expressed in populations of DRG neurons and dorsal horn neurons involved in the processing of pain. However, administration of capadenoson at established in vivo doses (0.03–1.0 mg/kg) did not alter mechanical hypersensitivity in the spared nerve injury and paclitaxel models of neuropathic pain, whereas the standard analgesic pregabalin significantly inhibited the pain behavior. Moreover, capadenoson failed to affect potassium currents in DRG neurons, in contrast to a full A1R agonist. Despite expression of A1R in nociceptive neurons, our data do not support the hypothesis that pharmacological intervention with partial A1R agonists might be a valuable approach for the treatment of neuropathic pain.
Collapse
Affiliation(s)
- Katharina Metzner
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
| | - Tilman Gross
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Annika Balzulat
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Gesine Wack
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Ruirui Lu
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Clinical Pharmacy, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
| |
Collapse
|
21
|
A Role for Transmembrane Protein 16C/Slack Impairment in Excitatory Nociceptive Synaptic Plasticity in the Pathogenesis of Remifentanil-induced Hyperalgesia in Rats. Neurosci Bull 2021; 37:669-683. [PMID: 33779892 DOI: 10.1007/s12264-021-00652-5] [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] [Received: 04/09/2020] [Accepted: 09/09/2020] [Indexed: 10/21/2022] Open
Abstract
Remifentanil is widely used to control intraoperative pain. However, its analgesic effect is limited by the generation of postoperative hyperalgesia. In this study, we investigated whether the impairment of transmembrane protein 16C (TMEM16C)/Slack is required for α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic receptor (AMPAR) activation in remifentanil-induced postoperative hyperalgesia. Remifentanil anesthesia reduced the paw withdrawal threshold from 2 h to 48 h postoperatively, with a decrease in the expression of TMEM16C and Slack in the dorsal root ganglia (DRG) and spinal cord. Knockdown of TMEM16C in the DRG reduced the expression of Slack and elevated the basal peripheral sensitivity and AMPAR expression and function. Overexpression of TMEM16C in the DRG impaired remifentanil-induced ERK1/2 phosphorylation and behavioral hyperalgesia. AMPAR-mediated current and neuronal excitability were downregulated by TMEM16C overexpression in the spinal cord. Taken together, these findings suggest that TMEM16C/Slack regulation of excitatory synaptic plasticity via GluA1-containing AMPARs is critical in the pathogenesis of remifentanil-induced postoperative hyperalgesia in rats.
Collapse
|
22
|
Functional Coupling of Slack Channels and P2X3 Receptors Contributes to Neuropathic Pain Processing. Int J Mol Sci 2021; 22:ijms22010405. [PMID: 33401689 PMCID: PMC7795269 DOI: 10.3390/ijms22010405] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/19/2020] [Accepted: 12/29/2020] [Indexed: 12/16/2022] Open
Abstract
The sodium-activated potassium channel Slack (KNa1.1, Slo2.2, or Kcnt1) is highly expressed in populations of sensory neurons, where it mediates the sodium-activated potassium current (IKNa) and modulates neuronal activity. Previous studies suggest that Slack is involved in the processing of neuropathic pain. However, mechanisms underlying the regulation of Slack activity in this context are poorly understood. Using whole-cell patch-clamp recordings we found that Slack-mediated IKNa in sensory neurons of mice is reduced after peripheral nerve injury, thereby contributing to neuropathic pain hypersensitivity. Interestingly, Slack is closely associated with ATP-sensitive P2X3 receptors in a population of sensory neurons. In vitro experiments revealed that Slack-mediated IKNa may be bidirectionally modulated in response to P2X3 activation. Moreover, mice lacking Slack show altered nocifensive responses to P2X3 stimulation. Our study identifies P2X3/Slack signaling as a mechanism contributing to hypersensitivity after peripheral nerve injury and proposes a potential novel strategy for treatment of neuropathic pain.
Collapse
|
23
|
The Na +-activated K + channel Slack contributes to synaptic development and plasticity. Cell Mol Life Sci 2021; 78:7569-7587. [PMID: 34664085 PMCID: PMC8629810 DOI: 10.1007/s00018-021-03953-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 09/08/2021] [Accepted: 09/22/2021] [Indexed: 11/29/2022]
Abstract
Human mutations of the Na+-activated K+ channel Slack (KCNT1) are associated with epilepsy and intellectual disability. Accordingly, Slack knockout mice (Slack-/-) exhibit cognitive flexibility deficits in distinct behavioral tasks. So far, however, the underlying causes as well as the role of Slack in hippocampus-dependent memory functions remain enigmatic. We now report that infant (P6-P14) Slack-/- lack both hippocampal LTD and LTP, likely due to impaired NMDA receptor (NMDAR) signaling. Postsynaptic GluN2B levels are reduced in infant Slack-/-, evidenced by lower amplitudes of NMDAR-meditated excitatory postsynaptic potentials. Low GluN2B affected NMDAR-mediated Ca2+-influx, rendering cultured hippocampal Slack-/-neurons highly insensitive to the GluN2B-specific inhibitor Ro 25-6981. Furthermore, dephosphorylation of the AMPA receptor (AMPAR) subunit GluA1 at S845, which is involved in AMPAR endocytosis during homeostatic and neuromodulator-regulated plasticity, is reduced after chemical LTD (cLTD) in infant Slack-/-. We additionally detect a lack of mGluR-induced LTD in infant Slack-/-, possibly caused by upregulation of the recycling endosome-associated small GTPase Rab4 which might accelerate AMPAR recycling from early endosomes. Interestingly, LTP and mGluR LTD, but not LTD and S845 dephosphorylation after cLTD are restored in adult Slack-/-. This together with normalized expression levels of GluN2B and Rab4 hints to developmental "restoration" of LTP expression despite Slack ablation, whereas in infant and adult brain, NMDAR-dependent LTD induction depends on this channel. Based on the present findings, NMDAR and vesicular transport might represent novel targets for the therapy of intellectual disability associated with Slack mutations. Consequently, careful modulation of hippocampal Slack activity should also improve learning abilities.
Collapse
|
24
|
Shore AN, Colombo S, Tobin WF, Petri S, Cullen ER, Dominguez S, Bostick CD, Beaumont MA, Williams D, Khodagholy D, Yang M, Lutz CM, Peng Y, Gelinas JN, Goldstein DB, Boland MJ, Frankel WN, Weston MC. Reduced GABAergic Neuron Excitability, Altered Synaptic Connectivity, and Seizures in a KCNT1 Gain-of-Function Mouse Model of Childhood Epilepsy. Cell Rep 2020; 33:108303. [PMID: 33113364 PMCID: PMC7712469 DOI: 10.1016/j.celrep.2020.108303] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 08/06/2020] [Accepted: 10/01/2020] [Indexed: 01/07/2023] Open
Abstract
Gain-of-function (GOF) variants in K+ channels cause severe childhood epilepsies, but there are no mechanisms to explain how increased K+ currents lead to network hyperexcitability. Here, we introduce a human Na+-activated K+ (KNa) channel variant (KCNT1-Y796H) into mice and, using a multiplatform approach, find motor cortex hyperexcitability and early-onset seizures, phenotypes strikingly similar to those of human patients. Although the variant increases KNa currents in cortical excitatory and inhibitory neurons, there is an increase in the KNa current across subthreshold voltages only in inhibitory neurons, particularly in those with non-fast-spiking properties, resulting in inhibitory-neuron-specific impairments in excitability and action potential (AP) generation. We further observe evidence of synaptic rewiring, including increases in homotypic synaptic connectivity, accompanied by network hyperexcitability and hypersynchronicity. These findings support inhibitory-neuron-specific mechanisms in mediating the epileptogenic effects of KCNT1 channel GOF, offering cell-type-specific currents and effects as promising targets for therapeutic intervention.
Collapse
Affiliation(s)
- Amy N Shore
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sophie Colombo
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - William F Tobin
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Sabrina Petri
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Erin R Cullen
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA
| | - Soledad Dominguez
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Michael A Beaumont
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Axion BioSystems, Atlanta, GA 30309, USA
| | - Damian Williams
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | - Dion Khodagholy
- Department of Electrical Engineering, Columbia University, New York, NY 10032, USA
| | - Mu Yang
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA
| | | | - Yueqing Peng
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Jennifer N Gelinas
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - David B Goldstein
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Michael J Boland
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Genetics and Development, Columbia University, New York, NY 10032, USA
| | - Wayne N Frankel
- Institute for Genomic Medicine, Columbia University, New York, NY 10032, USA; Department of Neurology, Columbia University, New York, NY 10032, USA
| | - Matthew C Weston
- Department of Neurological Sciences, University of Vermont, Burlington, VT 05405, USA.
| |
Collapse
|
25
|
Smith PA. K + Channels in Primary Afferents and Their Role in Nerve Injury-Induced Pain. Front Cell Neurosci 2020; 14:566418. [PMID: 33093824 PMCID: PMC7528628 DOI: 10.3389/fncel.2020.566418] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 08/21/2020] [Indexed: 12/12/2022] Open
Abstract
Sensory abnormalities generated by nerve injury, peripheral neuropathy or disease are often expressed as neuropathic pain. This type of pain is frequently resistant to therapeutic intervention and may be intractable. Numerous studies have revealed the importance of enduring increases in primary afferent excitability and persistent spontaneous activity in the onset and maintenance of peripherally induced neuropathic pain. Some of this activity results from modulation, increased activity and /or expression of voltage-gated Na+ channels and hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. K+ channels expressed in dorsal root ganglia (DRG) include delayed rectifiers (Kv1.1, 1.2), A-channels (Kv1.4, 3.3, 3.4, 4.1, 4.2, and 4.3), KCNQ or M-channels (Kv7.2, 7.3, 7.4, and 7.5), ATP-sensitive channels (KIR6.2), Ca2+-activated K+ channels (KCa1.1, 2.1, 2.2, 2.3, and 3.1), Na+-activated K+ channels (KCa4.1 and 4.2) and two pore domain leak channels (K2p; TWIK related channels). Function of all K+ channel types is reduced via a multiplicity of processes leading to altered expression and/or post-translational modification. This also increases excitability of DRG cell bodies and nociceptive free nerve endings, alters axonal conduction and increases neurotransmitter release from primary afferent terminals in the spinal dorsal horn. Correlation of these cellular changes with behavioral studies provides almost indisputable evidence for K+ channel dysfunction in the onset and maintenance of neuropathic pain. This idea is underlined by the observation that selective impairment of just one subtype of DRG K+ channel can produce signs of pain in vivo. Whilst it is established that various mediators, including cytokines and growth factors bring about injury-induced changes in DRG function and excitability, evidence presently available points to a seminal role for interleukin 1β (IL-1β) in control of K+ channel function. Despite the current state of knowledge, attempts to target K+ channels for therapeutic pain management have met with limited success. This situation may change with the advent of personalized medicine. Identification of specific sensory abnormalities and genetic profiling of individual patients may predict therapeutic benefit of K+ channel activators.
Collapse
Affiliation(s)
- Peter A. Smith
- Department of Pharmacology and Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
| |
Collapse
|
26
|
Kessi M, Chen B, Peng J, Tang Y, Olatoutou E, He F, Yang L, Yin F. Intellectual Disability and Potassium Channelopathies: A Systematic Review. Front Genet 2020; 11:614. [PMID: 32655623 PMCID: PMC7324798 DOI: 10.3389/fgene.2020.00614] [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: 02/21/2020] [Accepted: 05/20/2020] [Indexed: 01/15/2023] Open
Abstract
Intellectual disability (ID) manifests prior to adulthood as severe limitations to intellectual function and adaptive behavior. The role of potassium channelopathies in ID is poorly understood. Therefore, we aimed to evaluate the relationship between ID and potassium channelopathies. We hypothesized that potassium channelopathies are strongly associated with ID initiation, and that both gain- and loss-of-function mutations lead to ID. This systematic review explores the burden of potassium channelopathies, possible mechanisms, advancements using animal models, therapies, and existing gaps. The literature search encompassed both PubMed and Embase up to October 2019. A total of 75 articles describing 338 cases were included in this review. Nineteen channelopathies were identified, affecting the following genes: KCNMA1, KCNN3, KCNT1, KCNT2, KCNJ10, KCNJ6, KCNJ11, KCNA2, KCNA4, KCND3, KCNH1, KCNQ2, KCNAB1, KCNQ3, KCNQ5, KCNC1, KCNB1, KCNC3, and KCTD3. Twelve of these genes presented both gain- and loss-of-function properties, three displayed gain-of-function only, three exhibited loss-of-function only, and one had unknown function. How gain- and loss-of-function mutations can both lead to ID remains largely unknown. We identified only a few animal studies that focused on the mechanisms of ID in relation to potassium channelopathies and some of the few available therapeutic options (channel openers or blockers) appear to offer limited efficacy. In conclusion, potassium channelopathies contribute to the initiation of ID in several instances and this review provides a comprehensive overview of which molecular players are involved in some of the most prominent disease phenotypes.
Collapse
Affiliation(s)
- Miriam Kessi
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China.,Kilimanjaro Christian Medical University College, Moshi, Tanzania.,Mawenzi Regional Referral Hospital, Moshi, Tanzania
| | - Baiyu Chen
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Jing Peng
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Yulin Tang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Eleonore Olatoutou
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fang He
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Lifen Yang
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| | - Fei Yin
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha, China.,Hunan Intellectual and Developmental Disabilities Research Center, Changsha, China
| |
Collapse
|
27
|
Rab27a Contributes to the Processing of Inflammatory Pain in Mice. Cells 2020; 9:cells9061488. [PMID: 32570938 PMCID: PMC7349490 DOI: 10.3390/cells9061488] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 06/13/2020] [Accepted: 06/15/2020] [Indexed: 12/26/2022] Open
Abstract
Tissue injury and inflammation may result in chronic pain, a severe debilitating disease that is associated with great impairment of quality of life. An increasing body of evidence indicates that members of the Rab family of small GTPases contribute to pain processing; however, their specific functions remain poorly understood. Here, we found using immunofluorescence staining and in situ hybridization that the small GTPase Rab27a is highly expressed in sensory neurons and in the superficial dorsal horn of the spinal cord of mice. Rab27a mutant mice, which carry a single-nucleotide missense mutation of Rab27a leading to the expression of a nonfunctional protein, show reduced mechanical hyperalgesia and spontaneous pain behavior in inflammatory pain models, while their responses to acute noxious mechanical and thermal stimuli is not affected. Our study uncovers a previously unrecognized function of Rab27a in the processing of persistent inflammatory pain in mice.
Collapse
|
28
|
Impaired motor skill learning and altered seizure susceptibility in mice with loss or gain of function of the Kcnt1 gene encoding Slack (K Na1.1) Na +-activated K + channels. Sci Rep 2020; 10:3213. [PMID: 32081855 PMCID: PMC7035262 DOI: 10.1038/s41598-020-60028-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 02/03/2020] [Indexed: 12/23/2022] Open
Abstract
Gain-of-function mutations in KCNT1, the gene encoding Slack (KNa1.1) channels, result in epilepsy of infancy with migrating focal seizures (EIMFS) and several other forms of epilepsy associated with severe intellectual disability. We have generated a mouse model of this condition by replacing the wild type gene with one encoding Kcnt1R455H, a cytoplasmic C-terminal mutation homologous to a human R474H variant that results in EIMFS. We compared behavior patterns and seizure activity in these mice with those of wild type mice and Kcnt1-/- mice. Complete loss of Kcnt1 produced deficits in open field behavior and motor skill learning. Although their thresholds for electrically and chemically induced seizures were similar to those of wild type animals, Kcnt1-/- mice were significantly protected from death after maximum electroshock-induced seizures. In contrast, homozygous Kcnt1R455H/R455H mice were embryonic lethal. Video-EEG monitoring of heterozygous Kcnt1+/R455H animals revealed persistent interictal spikes, spontaneous seizures and a substantially decreased threshold for pentylenetetrazole-induced seizures. Surprisingly, Kcnt1+/R455H mice were not impaired in tasks of exploratory behavior or procedural motor learning. These findings provide an animal model for EIMFS and suggest that Slack channels are required for the development of procedural learning and of pathways that link cortical seizures to other regions required for animal survival.
Collapse
|
29
|
Teixeira-Duarte CM, Fonseca F, Morais-Cabral JH. Activation of a nucleotide-dependent RCK domain requires binding of a cation cofactor to a conserved site. eLife 2019; 8:50661. [PMID: 31868587 PMCID: PMC6957272 DOI: 10.7554/elife.50661] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 12/22/2019] [Indexed: 12/24/2022] Open
Abstract
RCK domains regulate the activity of K+ channels and transporters in eukaryotic and prokaryotic organisms by responding to ions or nucleotides. The mechanisms of RCK activation by Ca2+ in the eukaryotic BK and bacterial MthK K+ channels are well understood. However, the molecular details of activation in nucleotide-dependent RCK domains are not clear. Through a functional and structural analysis of the mechanism of ATP activation in KtrA, a RCK domain from the B. subtilis KtrAB cation channel, we have found that activation by nucleotide requires binding of cations to an intra-dimer interface site in the RCK dimer. In particular, divalent cations are coordinated by the γ-phosphates of bound-ATP, tethering the two subunits and stabilizing the active state conformation. Strikingly, the binding site residues are highly conserved in many different nucleotide-dependent RCK domains, indicating that divalent cations are a general cofactor in the regulatory mechanism of many nucleotide-dependent RCK domains.
Collapse
Affiliation(s)
- Celso M Teixeira-Duarte
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Fátima Fonseca
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| |
Collapse
|
30
|
An Epilepsy-Associated KCNT1 Mutation Enhances Excitability of Human iPSC-Derived Neurons by Increasing Slack K Na Currents. J Neurosci 2019; 39:7438-7449. [PMID: 31350261 DOI: 10.1523/jneurosci.1628-18.2019] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Revised: 07/08/2019] [Accepted: 07/17/2019] [Indexed: 12/26/2022] Open
Abstract
Mutations in the KCNT1 (Slack, KNa1.1) sodium-activated potassium channel produce severe epileptic encephalopathies. Expression in heterologous systems has shown that the disease-causing mutations give rise to channels that have increased current amplitude. It is not known, however, whether such gain of function occurs in human neurons, nor whether such increased KNa current is expected to suppress or increase the excitability of cortical neurons. Using genetically engineered human induced pluripotent stem cell (iPSC)-derived neurons, we have now found that sodium-dependent potassium currents are increased several-fold in neurons bearing a homozygous P924L mutation. In current-clamp recordings, the increased KNa current in neurons with the P924L mutation acts to shorten the duration of action potentials and to increase the amplitude of the afterhyperpolarization that follows each action potential. Strikingly, the number of action potentials that were evoked by depolarizing currents as well as maximal firing rates were increased in neurons expressing the mutant channel. In networks of spontaneously active neurons, the mean firing rate, the occurrence of rapid bursts of action potentials, and the intensity of firing during the burst were all increased in neurons with the P924L Slack mutation. The feasibility of an increased KNa current to increase firing rates independent of any compensatory changes was validated by numerical simulations. Our findings indicate that gain-of-function in Slack KNa channels causes hyperexcitability in both isolated neurons and in neural networks and occurs by a cell-autonomous mechanism that does not require network interactions.SIGNIFICANCE STATEMENT KCNT1 mutations lead to severe epileptic encephalopathies for which there are no effective treatments. This study is the first demonstration that a KCNT1 mutation increases the Slack current in neurons. It also provides the first explanation for how this increased potassium current induces hyperexcitability, which could be the underlining factor causing seizures.
Collapse
|
31
|
Schmiedl S, Peters D, Schmalz O, Mielke A, Rossmanith T, Diop S, Piefke M, Thürmann P, Schmidtko A. Loxapine for Treatment of Patients With Refractory, Chemotherapy-Induced Neuropathic Pain: A Prematurely Terminated Pilot Study Showing Efficacy But Limited Tolerability. Front Pharmacol 2019; 10:838. [PMID: 31402867 PMCID: PMC6669235 DOI: 10.3389/fphar.2019.00838] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 07/01/2019] [Indexed: 12/25/2022] Open
Abstract
Neuropathic pain is a debilitating and commonly treatment-refractory condition requiring novel therapeutic options. Accumulating preclinical studies indicate that the potassium channel Slack (KNa1.1) contributes to the processing of neuropathic pain, and that Slack activators, when injected into mice, ameliorate pain-related hypersensitivity. However, whether Slack activation might reduce neuropathic pain in humans remains elusive. Here, we evaluated the tolerability and analgesic efficacy of loxapine, a first-generation antipsychotic drug and Slack activator, in neuropathic pain patients. We aimed to treat 12 patients with chronic chemotherapy-induced, treatment-refractory neuropathic pain (pain severity ≥ 4 units on an 11-point numerical rating scale) in a monocentric, open label, proof-of-principle study. Patients received loxapine orally as add-on analgesic in a dose-escalating manner (four treatment episodes for 14 days, daily dose: 20, 30, 40, or 60 mg loxapine) depending on tolerability and analgesic efficacy. Patient-reported outcomes of pain intensity and/or relief were recorded daily. After enrolling four patients, this study was prematurely terminated due to adverse events typically occurring with first-generation antipsychotic drugs that were reported by all patients. In two patients receiving loxapine for at least two treatment episodes, a clinically relevant analgesic effect was found at a daily dose of 20-30 mg of loxapine. Another two patients tolerated loxapine only for a few days. Together, our data further support the hypothesis that Slack activation might be a novel strategy for neuropathic pain therapy. However, loxapine is no valid treatment option for painful polyneuropathy due to profound dopamine and histamine receptor-related side effects. Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT02820519.
Collapse
Affiliation(s)
- Sven Schmiedl
- Philipp Klee-Institute for Clinical Pharmacology, Helios University Hospital Wuppertal, Wuppertal, Germany.,Department of Clinical Pharmacology, School of Medicine, Faculty of Health, Witten/Herdecke University, Witten, Germany
| | - David Peters
- Philipp Klee-Institute for Clinical Pharmacology, Helios University Hospital Wuppertal, Wuppertal, Germany.,Department of Clinical Pharmacology, School of Medicine, Faculty of Health, Witten/Herdecke University, Witten, Germany
| | - Oliver Schmalz
- Clinic of Internal Medicine I, Division of Oncology and Palliative Care, Helios University Hospital Wuppertal, Wuppertal, Germany
| | - Anke Mielke
- Clinic for Anesthesiology, Pain Management Unit, Helios University Hospital Wuppertal, Wuppertal, Germany
| | - Tanja Rossmanith
- Fraunhofer Institute for Molecular Biology and Applied Ecology (IME), branch for Translational Medicine and Pharmacology of the Fraunhofer IME, Frankfurt, Germany
| | - Shirin Diop
- Neurobiology and Genetics of Behavior, Department of Psychology and Psychotherapy, Centre for Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Martina Piefke
- Neurobiology and Genetics of Behavior, Department of Psychology and Psychotherapy, Centre for Biomedical Education and Research (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Petra Thürmann
- Philipp Klee-Institute for Clinical Pharmacology, Helios University Hospital Wuppertal, Wuppertal, Germany.,Department of Clinical Pharmacology, School of Medicine, Faculty of Health, Witten/Herdecke University, Witten, Germany
| | - Achim Schmidtko
- Institute of Pharmacology and Toxicology, Centre for Biomedical Education and Research (ZBAF), School of Medicine, Faculty of Health, Witten/Herdecke University, Witten, Germany.,Institute of Pharmacology and Clinical Pharmacy, College of Pharmacy, Goethe University, Frankfurt, Germany
| |
Collapse
|
32
|
Distinct functions of soluble guanylyl cyclase isoforms NO-GC1 and NO-GC2 in inflammatory and neuropathic pain processing. Pain 2019; 160:607-618. [PMID: 30422870 DOI: 10.1097/j.pain.0000000000001440] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A large body of evidence indicates that nitric oxide (NO)/cGMP signaling essentially contributes to the processing of chronic pain. In general, NO-induced cGMP formation is catalyzed by 2 isoforms of guanylyl cyclase, NO-sensitive guanylyl cyclase 1 (NO-GC1) and 2 (NO-GC2). However, the specific functions of the 2 isoforms in pain processing remain elusive. Here, we investigated the distribution of NO-GC1 and NO-GC2 in the spinal cord and dorsal root ganglia, and we characterized the behavior of mice lacking either isoform in animal models of pain. Using immunohistochemistry and in situ hybridization, we demonstrate that both isoforms are localized to interneurons in the spinal dorsal horn with NO-GC1 being enriched in inhibitory interneurons. In dorsal root ganglia, the distribution of NO-GC1 and NO-GC2 is restricted to non-neuronal cells with NO-GC2 being the major isoform in satellite glial cells. Mice lacking NO-GC1 demonstrated reduced hypersensitivity in models of neuropathic pain, whereas their behavior in models of inflammatory pain was normal. By contrast, mice lacking NO-GC2 exhibited increased hypersensitivity in models of inflammatory pain, but their neuropathic pain behavior was unaltered. Cre-mediated deletion of NO-GC1 or NO-GC2 in spinal dorsal horn neurons recapitulated the behavioral phenotypes observed in the global knockout. Together, these results indicate that cGMP produced by NO-GC1 or NO-GC2 in spinal dorsal horn neurons exert distinct, and partly opposing, functions in chronic pain processing.
Collapse
|
33
|
Pryce KD, Powell R, Agwa D, Evely KM, Sheehan GD, Nip A, Tomasello DL, Gururaj S, Bhattacharjee A. Magi-1 scaffolds Na V1.8 and Slack K Na channels in dorsal root ganglion neurons regulating excitability and pain. FASEB J 2019; 33:7315-7330. [PMID: 30860870 DOI: 10.1096/fj.201802454rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Voltage-dependent sodium (NaV) 1.8 channels regulate action potential generation in nociceptive neurons, identifying them as putative analgesic targets. Here, we show that NaV1.8 channel plasma membrane localization, retention, and stability occur through a direct interaction with the postsynaptic density-95/discs large/zonula occludens-1-and WW domain-containing scaffold protein called membrane-associated guanylate kinase with inverted orientation (Magi)-1. The neurophysiological roles of Magi-1 are largely unknown, but we found that dorsal root ganglion (DRG)-specific knockdown of Magi-1 attenuated thermal nociception and acute inflammatory pain and produced deficits in NaV1.8 protein expression. A competing cell-penetrating peptide mimetic derived from the NaV1.8 WW binding motif decreased sodium currents, reduced NaV1.8 protein expression, and produced hypoexcitability. Remarkably, a phosphorylated variant of the very same peptide caused an opposing increase in NaV1.8 surface expression and repetitive firing. Likewise, in vivo, the peptides produced diverging effects on nocifensive behavior. Additionally, we found that Magi-1 bound to sequence like a calcium-activated potassium channel sodium-activated (Slack) potassium channels, demonstrating macrocomplexing with NaV1.8 channels. Taken together, these findings emphasize Magi-1 as an essential scaffold for ion transport in DRG neurons and a central player in pain.-Pryce, K. D., Powell, R., Agwa, D., Evely, K. M., Sheehan, G. D., Nip, A., Tomasello, D. L., Gururaj, S., Bhattacharjee, A. Magi-1 scaffolds NaV1.8 and Slack KNa channels in dorsal root ganglion neurons regulating excitability and pain.
Collapse
Affiliation(s)
- Kerri D Pryce
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Rasheen Powell
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Dalia Agwa
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Katherine M Evely
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Garrett D Sheehan
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Allan Nip
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Danielle L Tomasello
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Sushmitha Gururaj
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Arin Bhattacharjee
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| |
Collapse
|
34
|
Sodium-activated potassium channels shape peripheral auditory function and activity of the primary auditory neurons in mice. Sci Rep 2019; 9:2573. [PMID: 30796290 PMCID: PMC6384918 DOI: 10.1038/s41598-019-39119-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 01/17/2019] [Indexed: 11/08/2022] Open
Abstract
Potassium (K+) channels shape the response properties of neurons. Although enormous progress has been made to characterize K+ channels in the primary auditory neurons, the molecular identities of many of these channels and their contributions to hearing in vivo remain unknown. Using a combination of RNA sequencing and single molecule fluorescent in situ hybridization, we localized expression of transcripts encoding the sodium-activated potassium channels KNa1.1 (SLO2.2/Slack) and KNa1.2 (SLO2.1/Slick) to the primary auditory neurons (spiral ganglion neurons, SGNs). To examine the contribution of these channels to function of the SGNs in vivo, we measured auditory brainstem responses in KNa1.1/1.2 double knockout (DKO) mice. Although auditory brainstem response (wave I) thresholds were not altered, the amplitudes of suprathreshold responses were reduced in DKO mice. This reduction in amplitude occurred despite normal numbers and molecular architecture of the SGNs and their synapses with the inner hair cells. Patch clamp electrophysiology of SGNs isolated from DKO mice displayed altered membrane properties, including reduced action potential thresholds and amplitudes. These findings show that KNa1 channel activity is essential for normal cochlear function and suggest that early forms of hearing loss may result from physiological changes in the activity of the primary auditory neurons.
Collapse
|
35
|
Evely KM, Pryce KD, Bausch AE, Lukowski R, Ruth P, Haj-Dahmane S, Bhattacharjee A. Slack K Na Channels Influence Dorsal Horn Synapses and Nociceptive Behavior. Mol Pain 2018; 13:1744806917714342. [PMID: 28604221 PMCID: PMC5486487 DOI: 10.1177/1744806917714342] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The sodium-activated potassium channel Slack (Kcnt1, Slo2.2) is highly expressed in dorsal root ganglion neurons where it regulates neuronal firing. Several studies have implicated the Slack channel in pain processing, but the precise mechanism or the levels within the sensory pathway where channels are involved remain unclear. Here, we furthered the behavioral characterization of Slack channel knockout mice and for the first time examined the role of Slack channels in the superficial, pain-processing lamina of the dorsal horn. We performed whole-cell recordings from spinal cord slices to examine the intrinsic and synaptic properties of putative inhibitory and excitatory lamina II interneurons. Slack channel deletion altered intrinsic properties and synaptic drive to favor an overall enhanced excitatory tone. We measured the amplitudes and paired pulse ratio of paired excitatory post-synaptic currents at primary afferent synapses evoked by electrical stimulation of the dorsal root entry zone. We found a substantial decrease in the paired pulse ratio at synapses in Slack deleted neurons compared to wildtype, indicating increased presynaptic release from primary afferents. Corroborating these data, plantar test showed Slack knockout mice have an enhanced nociceptive responsiveness to localized thermal stimuli compared to wildtype mice. Our findings suggest that Slack channels regulate synaptic transmission within the spinal cord dorsal horn and by doing so establishes the threshold for thermal nociception.
Collapse
Affiliation(s)
- Katherine M Evely
- Program in Neuroscience, University at Buffalo, The State University of New York, NY, USA
| | - Kerri D Pryce
- Department of Pharmacology and Toxicology, University at Buffalo, The State University of New York, NY, USA
| | - Anne E Bausch
- Institut für Pharmazie, Pharmakologie, Toxikologie und Klinische Pharmazie der Universität Tübingen, Germany
| | - Robert Lukowski
- Institut für Pharmazie, Pharmakologie, Toxikologie und Klinische Pharmazie der Universität Tübingen, Germany
| | - Peter Ruth
- Institut für Pharmazie, Pharmakologie, Toxikologie und Klinische Pharmazie der Universität Tübingen, Germany
| | - Samir Haj-Dahmane
- Program in Neuroscience, University at Buffalo, The State University of New York, NY, USA
| | | |
Collapse
|
36
|
Bausch AE, Ehinger R, Straubinger J, Zerfass P, Nann Y, Lukowski R. Loss of Sodium-Activated Potassium Channel Slack and FMRP Differentially Affect Social Behavior in Mice. Neuroscience 2018; 384:361-374. [DOI: 10.1016/j.neuroscience.2018.05.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Revised: 05/22/2018] [Accepted: 05/24/2018] [Indexed: 12/31/2022]
|
37
|
General Pathways of Pain Sensation and the Major Neurotransmitters Involved in Pain Regulation. Int J Mol Sci 2018; 19:ijms19082164. [PMID: 30042373 PMCID: PMC6121522 DOI: 10.3390/ijms19082164] [Citation(s) in RCA: 267] [Impact Index Per Article: 44.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 07/19/2018] [Accepted: 07/20/2018] [Indexed: 12/30/2022] Open
Abstract
Pain has been considered as a concept of sensation that we feel as a reaction to the stimulus of our surrounding, putting us in harm's way and acting as a form of defense mechanism that our body has permanently installed into its system. However, pain leads to a huge chunk of finances within the healthcare system with continuous rehabilitation of patients with adverse pain sensations, which might reduce not only their quality of life but also their productivity at work setting back the pace of our economy. It may not look like a huge deal but factor in pain as an issue for majority of us, it becomes an economical burden. Although pain has been researched into and understood by numerous researches, from its definition, mechanism of action to its inhibition in hopes of finding an absolute solution for victims of pain, the pathways of pain sensation, neurotransmitters involved in producing such a sensation are not comprehensively reviewed. Therefore, this review article aims to put in place a thorough understanding of major pain conditions that we experience-nociceptive, inflammatory and physiologically dysfunction, such as neuropathic pain and its modulation and feedback systems. Moreover, the complete mechanism of conduction is compiled within this article, elucidating understandings from various researches and breakthroughs.
Collapse
|
38
|
Regulation of Nociceptive Glutamatergic Signaling by Presynaptic Kv3.4 Channels in the Rat Spinal Dorsal Horn. J Neurosci 2018. [PMID: 29540546 DOI: 10.1523/jneurosci.3212-17.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Presynaptic voltage-gated K+ (Kv) channels in dorsal root ganglion (DRG) neurons are thought to regulate nociceptive synaptic transmission in the spinal dorsal horn. However, the Kv channel subtypes responsible for this critical role have not been identified. The Kv3.4 channel is particularly important because it is robustly expressed in DRG nociceptors, where it regulates action potential (AP) duration. Furthermore, Kv3.4 dysfunction is implicated in the pathophysiology of neuropathic pain in multiple pain models. We hypothesized that, through their ability to modulate AP repolarization, Kv3.4 channels in DRG nociceptors help to regulate nociceptive synaptic transmission. To test this hypothesis, we investigated Kv3.4 immunoreactivity (IR) in the rat cervical superficial dorsal horn (sDH) in both sexes and implemented an intact spinal cord preparation to investigate glutamatergic synaptic currents from second order neurons in the sDH under conditions that selectively inhibit the Kv3.4 current. We found presynaptic Kv3.4 IR in peptidergic and nonpeptidergic nociceptive fibers of the sDH. The Kv3.4 channel is hypersensitive to 4-aminopyridine and tetraethylammonium (TEA). Accordingly, 50 μm 4-aminopyridine and 500 μm TEA significantly prolong the AP, slow the maximum rate of repolarization in small-diameter DRG neurons, and potentiate monosynaptic excitatory postsynaptic currents (EPSCs) in dorsal horn laminae I and II through a presynaptic mechanism. In contrast, highly specific inhibitors of BK, Kv7, and Kv1 channels are less effective modulators of the AP and have little to no effect on EPSCs. The results strongly suggest that presynaptic Kv3.4 channels are major regulators of nociceptive synaptic transmission in the spinal cord.SIGNIFICANCE STATEMENT Intractable neuropathic pain can result from disease or traumatic injury and many studies have been conducted to determine the underlying pathophysiological changes. Voltage-gated ion channels, including the K+ channel Kv3.4, are dysregulated in multiple pain models. Kv3.4 channels are ubiquitously expressed in the dorsal root ganglion (DRG), where they are major regulators of DRG excitability. However, little is known about the ionic mechanisms that regulate nociceptive synaptic transmission at the level of the first synapse in the spinal cord, which is critical to pain transmission in both intact and pathological states. Here, we show that Kv3.4 channels have a significant impact on glutamatergic synaptic transmission in the dorsal horn, further illuminating its potential as a molecular pain therapeutic target.
Collapse
|
39
|
Tröster P, Haseleu J, Petersen J, Drees O, Schmidtko A, Schwaller F, Lewin GR, Ter-Avetisyan G, Winter Y, Peters S, Feil S, Feil R, Rathjen FG, Schmidt H. The Absence of Sensory Axon Bifurcation Affects Nociception and Termination Fields of Afferents in the Spinal Cord. Front Mol Neurosci 2018; 11:19. [PMID: 29472841 PMCID: PMC5809486 DOI: 10.3389/fnmol.2018.00019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 01/15/2018] [Indexed: 12/16/2022] Open
Abstract
A cGMP signaling cascade composed of C-type natriuretic peptide, the guanylyl cyclase receptor Npr2 and cGMP-dependent protein kinase I (cGKI) controls the bifurcation of sensory axons upon entering the spinal cord during embryonic development. However, the impact of axon bifurcation on sensory processing in adulthood remains poorly understood. To investigate the functional consequences of impaired axon bifurcation during adult stages we generated conditional mouse mutants of Npr2 and cGKI (Npr2fl/fl;Wnt1Cre and cGKIKO/fl;Wnt1Cre) that lack sensory axon bifurcation in the absence of additional phenotypes observed in the global knockout mice. Cholera toxin labeling in digits of the hind paw demonstrated an altered shape of sensory neuron termination fields in the spinal cord of conditional Npr2 mouse mutants. Behavioral testing of both sexes indicated that noxious heat sensation and nociception induced by chemical irritants are impaired in the mutants, whereas responses to cold sensation, mechanical stimulation, and motor coordination are not affected. Recordings from C-fiber nociceptors in the hind limb skin showed that Npr2 function was not required to maintain normal heat sensitivity of peripheral nociceptors. Thus, the altered behavioral responses to noxious heat found in Npr2fl/fl;Wnt1Cre mice is not due to an impaired C-fiber function. Overall, these data point to a critical role of axonal bifurcation for the processing of pain induced by heat or chemical stimuli.
Collapse
Affiliation(s)
- Philip Tröster
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Julia Haseleu
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Jonas Petersen
- Institute of Pharmacology, College of Pharmacy, Goethe University, Frankfurt am Main, Germany.,Institute of Pharmacology and Toxicology, Zentrum für Biomedizinische Ausbildung und Forschung (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Oliver Drees
- Institute of Pharmacology and Toxicology, Zentrum für Biomedizinische Ausbildung und Forschung (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Achim Schmidtko
- Institute of Pharmacology, College of Pharmacy, Goethe University, Frankfurt am Main, Germany.,Institute of Pharmacology and Toxicology, Zentrum für Biomedizinische Ausbildung und Forschung (ZBAF), Witten/Herdecke University, Witten, Germany
| | - Frederick Schwaller
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Gary R Lewin
- Molecular Physiology of Somatic Sensation, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Gohar Ter-Avetisyan
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - York Winter
- Cognitive Neurobiology, Humboldt University of Berlin, Berlin, Germany
| | - Stefanie Peters
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Susanne Feil
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Robert Feil
- Interfaculty Institute of Biochemistry, University of Tübingen, Tübingen, Germany
| | - Fritz G Rathjen
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Hannes Schmidt
- Developmental Neurobiology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| |
Collapse
|
40
|
HRPU-2, a Homolog of Mammalian hnRNP U, Regulates Synaptic Transmission by Controlling the Expression of SLO-2 Potassium Channel in Caenorhabditis elegans. J Neurosci 2017; 38:1073-1084. [PMID: 29217678 DOI: 10.1523/jneurosci.1991-17.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/27/2017] [Accepted: 12/02/2017] [Indexed: 12/22/2022] Open
Abstract
Slo2 channels are large-conductance potassium channels abundantly expressed in the nervous system. However, it is unclear how their expression level in neurons is regulated. Here we report that HRPU-2, an RNA-binding protein homologous to mammalian heterogeneous nuclear ribonucleoprotein U (hnRNP U), plays an important role in regulating the expression of SLO-2 (a homolog of mammalian Slo2) in Caenorhabditis elegans Loss-of-function (lf) mutants of hrpu-2 were isolated in a genetic screen for suppressors of a sluggish phenotype caused by a hyperactive SLO-2. In hrpu-2(lf) mutants, SLO-2-mediated delayed outward currents in neurons are greatly decreased, and neuromuscular synaptic transmission is enhanced. These mutant phenotypes can be rescued by expressing wild-type HRPU-2 in neurons. HRPU-2 binds to slo-2 mRNA, and hrpu-2(lf) mutants show decreased SLO-2 protein expression. In contrast, hrpu-2(lf) does not alter the expression of either the BK channel SLO-1 or the Shaker type potassium channel SHK-1. hrpu-2(lf) mutants are indistinguishable from wild type in gross motor neuron morphology and locomotion behavior. Together, these observations suggest that HRPU-2 plays important roles in SLO-2 function by regulating SLO-2 protein expression, and that SLO-2 is likely among a restricted set of proteins regulated by HRPU-2. Mutations of human Slo2 channel and hnRNP U are strongly linked to epileptic disorders and intellectual disability. The findings of this study suggest a potential link between these two molecules in human patients.SIGNIFICANCE STATEMENT Heterogeneous nuclear ribonucleoprotein U (hnRNP U) belongs to a family of RNA-binding proteins that play important roles in controlling gene expression. Recent studies have established a strong link between mutations of hnRNP U and human epilepsies and intellectual disability. However, it is unclear how mutations of hnRNP U may cause such disorders. This study shows that mutations of HRPU-2, a worm homolog of mammalian hnRNP U, result in dysfunction of a Slo2 potassium channel, which is critical to neuronal function. Because mutations of Slo2 channels are also strongly associated with epileptic encephalopathies and intellectual disability in humans, the findings of this study point to a potential mechanism underlying neurological disorders caused by hnRNP U mutations.
Collapse
|
41
|
Gururaj S, Evely KM, Pryce KD, Li J, Qu J, Bhattacharjee A. Protein kinase A-induced internalization of Slack channels from the neuronal membrane occurs by adaptor protein-2/clathrin-mediated endocytosis. J Biol Chem 2017; 292:19304-19314. [PMID: 28982974 DOI: 10.1074/jbc.m117.804716] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 09/13/2017] [Indexed: 02/01/2023] Open
Abstract
The sodium-activated potassium (KNa) channel Kcnt1 (Slack) is abundantly expressed in nociceptor (pain-sensing) neurons of the dorsal root ganglion (DRG), where they transmit the large outward conductance IKNa and arbitrate membrane excitability. Slack channel expression at the DRG membrane is necessary for their characteristic firing accommodation during maintained stimulation, and reduced membrane channel density causes hyperexcitability. We have previously shown that in a pro-inflammatory state, a decrease in membrane channel expression leading to reduced Slack-mediated IKNa expression underlies DRG neuronal sensitization. An important component of the inflammatory milieu, PKA internalizes Slack channels from the DRG membrane, reduces IKNa, and produces DRG neuronal hyperexcitability when activated in cultured primary DRG neurons. Here, we show that this PKA-induced retrograde trafficking of Slack channels also occurs in intact spinal cord slices and that it is carried out by adaptor protein-2 (AP-2) via clathrin-mediated endocytosis. We provide mass spectrometric and biochemical evidence of an association of native neuronal AP-2 adaptor proteins with Slack channels, facilitated by a dileucine motif housed in the cytoplasmic Slack C terminus that binds AP-2. By creating a competitive peptide blocker of AP-2-Slack binding, we demonstrated that this interaction is essential for clathrin recruitment to the DRG membrane, Slack channel endocytosis, and DRG neuronal hyperexcitability after PKA activation. Together, these findings uncover AP-2 and clathrin as players in Slack channel regulation. Given the significant role of Slack in nociceptive neuronal excitability, the AP-2 clathrin-mediated endocytosis trafficking mechanism may enable targeting of peripheral and possibly, central neuronal sensitization.
Collapse
Affiliation(s)
| | - Katherine M Evely
- the Program for Neuroscience, University at Buffalo, State University of New York, Buffalo, New York 14214 and
| | - Kerri D Pryce
- From the Department of Pharmacology and Toxicology and
| | - Jun Li
- the New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York 14203
| | - Jun Qu
- the New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, New York 14203
| | - Arin Bhattacharjee
- From the Department of Pharmacology and Toxicology and .,the Program for Neuroscience, University at Buffalo, State University of New York, Buffalo, New York 14214 and
| |
Collapse
|
42
|
Tomasello DL, Hurley E, Wrabetz L, Bhattacharjee A. Slick (Kcnt2) Sodium-Activated Potassium Channels Limit Peptidergic Nociceptor Excitability and Hyperalgesia. J Exp Neurosci 2017; 11:1179069517726996. [PMID: 28943756 PMCID: PMC5602212 DOI: 10.1177/1179069517726996] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/25/2017] [Indexed: 01/21/2023] Open
Abstract
The Slick (Kcnt2) sodium-activated potassium (KNa) channel is a rapidly gating and weakly voltage-dependent and sodium-dependent potassium channel with no clearly defined physiological function. Within the dorsal root ganglia (DRGs), we show Slick channels are exclusively expressed in small-sized and medium-sized calcitonin gene–related peptide (CGRP)-containing DRG neurons, and a pool of channels are localized to large dense-core vesicles (LDCV)-containing CGRP. We stimulated DRG neurons for CGRP release and found Slick channels contained within CGRP-positive LDCV translocated to the neuronal membrane. Behavioral studies in Slick knockout (KO) mice indicated increased basal heat detection and exacerbated thermal hyperalgesia compared with wild-type littermate controls during neuropathic and chronic inflammatory pain. Electrophysiologic recordings of DRG neurons from Slick KO mice revealed that Slick channels contribute to outward current, propensity to fire action potentials (APs), and to AP properties. Our data suggest that Slick channels restrain the excitability of CGRP-containing neurons, diminishing pain behavior after inflammation and injury.
Collapse
Affiliation(s)
- Danielle L Tomasello
- Neuroscience Program, The State University of New York - University at Buffalo, Buffalo, NY, USA
| | - Edward Hurley
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York - University at Buffalo, Buffalo, NY, USA
| | - Lawrence Wrabetz
- Department of Neurology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York - University at Buffalo, Buffalo, NY, USA
| | - Arin Bhattacharjee
- Neuroscience Program, The State University of New York - University at Buffalo, Buffalo, NY, USA.,Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, The State University of New York - University at Buffalo, Buffalo, NY, USA
| |
Collapse
|
43
|
Lu R, Flauaus C, Kennel L, Petersen J, Drees O, Kallenborn-Gerhardt W, Ruth P, Lukowski R, Schmidtko A. K Ca3.1 channels modulate the processing of noxious chemical stimuli in mice. Neuropharmacology 2017; 125:386-395. [PMID: 28823609 DOI: 10.1016/j.neuropharm.2017.08.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2017] [Revised: 06/26/2017] [Accepted: 08/16/2017] [Indexed: 12/19/2022]
Abstract
Intermediate conductance calcium-activated potassium channels (KCa3.1) have been recently implicated in pain processing. However, the functional role and localization of KCa3.1 in the nociceptive system are largely unknown. We here characterized the behavior of mice lacking KCa3.1 (KCa3.1-/-) in various pain models and analyzed the expression pattern of KCa3.1 in dorsal root ganglia (DRG) and the spinal cord. KCa3.1-/- mice demonstrated normal behavioral responses in models of acute nociceptive, persistent inflammatory, and persistent neuropathic pain. However, their behavioral responses to noxious chemical stimuli such as formalin and capsaicin were increased. Accordingly, formalin-induced nociceptive behavior was increased in wild-type mice after administration of the KCa3.1 inhibitor TRAM-34. In situ hybridization experiments detected KCa3.1 in most DRG satellite glial cells, in a minority of DRG neurons, and in ependymal cells lining the central canal of the spinal cord. Together, our data point to a specific inhibitory role of KCa3.1 for the processing of noxious chemical stimuli.
Collapse
Affiliation(s)
- Ruirui Lu
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany; Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany.
| | - Cathrin Flauaus
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany
| | - Lea Kennel
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany
| | - Jonas Petersen
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany; Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany
| | - Oliver Drees
- Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany
| | - Wiebke Kallenborn-Gerhardt
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany
| | - Peter Ruth
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Universität Tübingen, 72076 Tübingen, Germany
| | - Robert Lukowski
- Pharmakologie, Toxikologie und Klinische Pharmazie, Institut für Pharmazie, Universität Tübingen, 72076 Tübingen, Germany
| | - Achim Schmidtko
- Pharmakologisches Institut für Naturwissenschaftler, Goethe-Universität, Fachbereich Biochemie, Chemie und Pharmazie, 60438 Frankfurt am Main, Germany; Institut für Pharmakologie und Toxikologie, Universität Witten/Herdecke, ZBAF, 58453 Witten, Germany
| |
Collapse
|
44
|
Abstract
Acute and chronic pain complaints, although common, are generally poorly served by existing therapies. This unmet clinical need reflects a failure to develop novel classes of analgesics with superior efficacy, diminished adverse effects and a lower abuse liability than those currently available. Reasons for this include the heterogeneity of clinical pain conditions, the complexity and diversity of underlying pathophysiological mechanisms, and the unreliability of some preclinical pain models. However, recent advances in our understanding of the neurobiology of pain are beginning to offer opportunities for developing novel therapeutic strategies and revisiting existing targets, including modulating ion channels, enzymes and G-protein-coupled receptors.
Collapse
|
45
|
|
46
|
The Phe932Ile mutation in KCNT1 channels associated with severe epilepsy, delayed myelination and leukoencephalopathy produces a loss-of-function channel phenotype. Neuroscience 2017; 351:65-70. [PMID: 28366665 DOI: 10.1016/j.neuroscience.2017.03.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Revised: 03/08/2017] [Accepted: 03/22/2017] [Indexed: 12/13/2022]
Abstract
Sodium-activated potassium (KNa) channels contribute to firing frequency adaptation and slow after hyperpolarization. The KCNT1 gene (also known as SLACK) encodes a KNa subunit that is expressed throughout the central and peripheral nervous systems. Missense mutations of the SLACK C-terminus have been reported in several patients with rare forms of early onset epilepsy and in some cases severely delayed myelination. To date, such mutations identified in patients with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), epilepsy of infancy with migrating focal seizures (EIMFS) and Ohtahara syndrome (OS) have been reported to be gain-of-function mutations (Villa and Combi, 2016). An exome sequencing study identified a p.Phe932Ile KCNT1 mutation as the disease-causing change in a child with severe early infantile epileptic encephalopathy and abnormal myelination (Vanderver et al., 2014). We characterized an analogous mutation in the rat Slack channel and unexpectedly found this mutation to produce a loss-of-function phenotype. In an effort to restore current, we tested the known Slack channel opener loxapine. Loxapine exhibited no effect, indicating that this mutation either caused the channel to be insensitive to this established opener or proper translation and trafficking to the membrane was disrupted. Protein analysis confirmed that while total mutant protein did not differ from wild type, membrane expression of the mutant channel was substantially reduced. Although gain-of-function mutations to the Slack channel are linked to epileptic phenotypes, this is the first reported loss-of-function mutation linked to severe epilepsy and delayed myelination.
Collapse
|
47
|
Kaczmarek LK, Aldrich RW, Chandy KG, Grissmer S, Wei AD, Wulff H. International Union of Basic and Clinical Pharmacology. C. Nomenclature and Properties of Calcium-Activated and Sodium-Activated Potassium Channels. Pharmacol Rev 2017; 69:1-11. [PMID: 28267675 PMCID: PMC11060434 DOI: 10.1124/pr.116.012864] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024] Open
Abstract
A subset of potassium channels is regulated primarily by changes in the cytoplasmic concentration of ions, including calcium, sodium, chloride, and protons. The eight members of this subfamily were originally all designated as calcium-activated channels. More recent studies have clarified the gating mechanisms for these channels and have documented that not all members are sensitive to calcium. This article describes the molecular relationships between these channels and provides an introduction to their functional properties. It also introduces a new nomenclature that differentiates between calcium- and sodium-activated potassium channels.
Collapse
Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Richard W Aldrich
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - K George Chandy
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Stephan Grissmer
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Aguan D Wei
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Heike Wulff
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| |
Collapse
|
48
|
Giese MH, Gardner A, Hansen A, Sanguinetti MC. Molecular mechanisms of Slo2 K + channel closure. J Physiol 2016; 595:2321-2336. [PMID: 27682982 DOI: 10.1113/jp273225] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 09/20/2016] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Intracellular Na+ -activated Slo2 potassium channels are in a closed state under normal physiological conditions, although their mechanisms of ion permeation gating are not well understood. A cryo-electron microscopy structure of Slo2.2 suggests that the ion permeation pathway of these channels is closed by a single constriction of the inner pore formed by the criss-crossing of the cytoplasmic ends of the S6 segments (the S6 bundle crossing) at a conserved Met residue. Functional characterization of mutant Slo2 channels suggests that hydrophobic interactions between Leu residues in the upper region of the S6 segments contribute to stabilizing the inner pore in a non-conducting state. Mutation of the conserved Met residues in the S6 segments to the negatively-charged Glu did not induce constitutive opening of Slo2.1 or Slo2.2, suggesting that ion permeation of Slo2 channels is not predominantly gated by the S6 bundle crossing. ABSTRACT Large conductance K+ -selective Slo2 channels are in a closed state unless activated by elevated [Na+ ]i . Our previous studies suggested that the pore helix/selectivity filter serves as the activation gate in Slo2 channels. In the present study, we evaluated two other potential mechanisms for stabilization of Slo2 channels in a closed state: (1) dewetting and collapse of the inner pore (hydrophobic gating) and (2) constriction of the inner pore by tight criss-crossing of the cytoplasmic ends of the S6 α-helical segments. Slo2 channels contain two conserved Leu residues in each of the four S6 segments that line the inner pore region nearest the bottom of the selectivity filter. To evaluate the potential role of these residues in hydrophobic gating, Leu267 and Leu270 in human Slo2.1 were each replaced by 15 different residues. The relative conductance of mutant channels was highly dependent on hydrophilicity and volume of the amino acid substituted for Leu267 and was maximal with L267H. Consistent with their combined role in hydrophobic gating, replacement of both Leu residues with the isosteric but polar residue Asn (L267N/L270N) stabilized channels in a fully open state. In a recent cryo-electron microscopy structure of chicken Slo2.2, the ion permeation pathway of the channel is closed by a constriction of the inner pore formed by criss-crossing of the S6 segments at a conserved Met. Inconsistent with the S6 segment crossing forming the activation gate, replacement of the homologous Met residues in human Slo2.1 or Slo2.2 with the negatively-charged Glu did not induce constitutive channel opening.
Collapse
Affiliation(s)
- M Hunter Giese
- Nora Eccles Harrison Cardiovascular Research & Training Institute
| | - Alison Gardner
- Nora Eccles Harrison Cardiovascular Research & Training Institute
| | - Angela Hansen
- Nora Eccles Harrison Cardiovascular Research & Training Institute
| | - Michael C Sanguinetti
- Nora Eccles Harrison Cardiovascular Research & Training Institute.,Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, UT, USA
| |
Collapse
|
49
|
Targeting CYP2J to reduce paclitaxel-induced peripheral neuropathic pain. Proc Natl Acad Sci U S A 2016; 113:12544-12549. [PMID: 27791151 DOI: 10.1073/pnas.1613246113] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Chemotherapy-induced peripheral neuropathic pain (CIPNP) is a severe dose- and therapy-limiting side effect of widely used cytostatics that is particularly difficult to treat. Here, we report increased expression of the cytochrome-P450-epoxygenase CYP2J6 and increased concentrations of its linoleic acid metabolite 9,10-EpOME (9,10-epoxy-12Z-octadecenoic acid) in dorsal root ganglia (DRGs) of paclitaxel-treated mice as a model of CIPNP. The lipid sensitizes TRPV1 ion channels in primary sensory neurons and causes increased frequency of spontaneous excitatory postsynaptic currents in spinal cord nociceptive neurons, increased CGRP release from sciatic nerves and DRGs, and a reduction in mechanical and thermal pain hypersensitivity. In a drug repurposing screen targeting CYP2J2, the human ortholog of murine CYP2J6, we identified telmisartan, a widely used angiotensin II receptor antagonist, as a potent inhibitor. In a translational approach, administration of telmisartan reduces EpOME concentrations in DRGs and in plasma and reverses mechanical hypersensitivity in paclitaxel-treated mice. We therefore suggest inhibition of CYP2J isoforms with telmisartan as a treatment option for paclitaxel-induced neuropathic pain.
Collapse
|
50
|
Stimulation of Slack K(+) Channels Alters Mass at the Plasma Membrane by Triggering Dissociation of a Phosphatase-Regulatory Complex. Cell Rep 2016; 16:2281-8. [PMID: 27545877 DOI: 10.1016/j.celrep.2016.07.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 09/27/2015] [Accepted: 07/13/2016] [Indexed: 11/23/2022] Open
Abstract
Human mutations in the cytoplasmic C-terminal domain of Slack sodium-activated potassium (KNa) channels result in childhood epilepsy with severe intellectual disability. Slack currents can be increased by pharmacological activators or by phosphorylation of a Slack C-terminal residue by protein kinase C. Using an optical biosensor assay, we find that Slack channel stimulation in neurons or transfected cells produces loss of mass near the plasma membrane. Slack mutants associated with intellectual disability fail to trigger any change in mass. The loss of mass results from the dissociation of the protein phosphatase 1 (PP1) targeting protein, Phactr-1, from the channel. Phactr1 dissociation is specific to wild-type Slack channels and is not observed when related potassium channels are stimulated. Our findings suggest that Slack channels are coupled to cytoplasmic signaling pathways and that dysregulation of this coupling may trigger the aberrant intellectual development associated with specific childhood epilepsies.
Collapse
|