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Stevens-Sostre WA, Flores-Aldama L, Bustos D, Li J, Morais-Cabral JH, Delemotte L, Robertson GA. An intracellular hydrophobic nexus critical for hERG1 channel slow deactivation. Biophys J 2024; 123:2024-2037. [PMID: 38219015 PMCID: PMC11309987 DOI: 10.1016/j.bpj.2024.01.010] [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: 08/28/2023] [Revised: 11/17/2023] [Accepted: 01/09/2024] [Indexed: 01/15/2024] Open
Abstract
Slow deactivation is a critical property of voltage-gated K+ channels encoded by the human Ether-à-go-go-Related Gene 1 (hERG). hERG1 channel deactivation is modulated by interactions between intracellular N-terminal Per-Arnt-Sim (PAS) and C-terminal cyclic nucleotide-binding homology (CNBh) domains. The PAS domain is multipartite, comprising a globular domain (gPAS; residues 26-135) and an N-terminal PAS-cap that is further subdivided into an initial unstructured "tip" (residues 1-12) and an amphipathic α-helical region (residues 13-25). Although the PAS-cap tip has long been considered the effector of slow deactivation, how its position near the gating machinery is controlled has not been elucidated. Here, we show that a triad of hydrophobic interactions among the gPAS, PAS-cap α helix, and the CNBh domains is required to support slow deactivation in hERG1. The primary sequence of this "hydrophobic nexus" is highly conserved among mammalian ERG channels but shows key differences to fast-deactivating Ether-à-go-go 1 (EAG1) channels. Combining sequence analysis, structure-directed mutagenesis, electrophysiology, and molecular dynamics simulations, we demonstrate that polar serine substitutions uncover an intermediate deactivation mode that is also mimicked by deletion of the PAS-cap α helix. Molecular dynamics simulation analyses of the serine-substituted channels show an increase in distance among the residues of the hydrophobic nexus, a rotation of the intracellular gating ring, and a retraction of the PAS-cap tip from its receptor site near the voltage sensor domain and channel gate. These findings provide compelling evidence that the hydrophobic nexus coordinates the respective components of the intracellular gating ring and positions the PAS-cap tip to control hERG1 deactivation gating.
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Affiliation(s)
- Whitney A Stevens-Sostre
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Lisandra Flores-Aldama
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Daniel Bustos
- Centro de Investigación de Estudios Avanzados Del Maule (CIEAM), Vicerrectoría de Investigación y Postgrado, Universidad Católica Del Maule, Talca, Chile; Laboratorio de Bioinformática y Química Computacional (LBQC), Departamento de Medicina Traslacional, Facultad de Medicina, Universidad Católica Del Maule, Talca, Chile
| | - Jin Li
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação Em Saude da Universidade Do Porto (i3S); Instituto de Biologia Molecular e Celular, Universidade Do Porto, Porto, Portugal
| | - Lucie Delemotte
- KTH Royal Institute of Technology, Science for Life Laboratory, Stockholm, Sweden
| | - Gail A Robertson
- Department of Neuroscience, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin.
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2
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Memo C, Parisse P, Amoriello R, Pachetti M, Palandri A, Casalis L, Ballerini C, Ballerini L. Extracellular vesicles released by LPS-stimulated spinal organotypic slices spread neuroinflammation into naïve slices through connexin43 hemichannel opening and astrocyte aberrant calcium dynamics. Front Cell Neurosci 2024; 18:1433309. [PMID: 39049826 PMCID: PMC11266295 DOI: 10.3389/fncel.2024.1433309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Accepted: 06/20/2024] [Indexed: 07/27/2024] Open
Abstract
Introduction Neuroinflammation is a hallmark of multiple neurodegenerative diseases, shared by all pathological processes which primarily impact on neurons, including Central Nervous System (CNS) injuries. In reactive CNS, activated glia releases extracellular vesicles (EVs), nanosized membranous particles known to play a key role in intercellular communication. EVs mediate neuroinflammatory responses and might exacerbate tissue deterioration, ultimately influencing neurodegenerative disease progression. Methods We treated spinal cord organotypic slices with LPS, a ligand extensively used to induce sEVs release, to mimic mild inflammatory conditions. We combine atomic force microscopy (AFM), nanoparticle tracking (NTA) and western blot (WB) analysis to validate the isolation and characterisation of sEVs. We further use immunofluorescence and confocal microscopy with live calcium imaging by GCaMP6f reporter to compare glial reactivity to treatments with sEVs when isolated from resting and LPS treated organ slices. Results In our study, we focus on CNS released small EVs (sEVs) and their impact on the biology of inflammatory environment. We address sEVs local signalling within the CNS tissue, in particular their involvement in inflammation spreading mechanism(s). sEVs are harvested from mouse organotypic spinal cord cultures, an in vitro model which features 3D complexity and retains spinal cord resident cells. By confocal microscopy and live calcium imaging we monitor glial responses in naïve spinal slices when exposed to sEVs isolated from resting and LPS treated organ slices. Discussion We show that sEVs, only when released during LPS neuroinflammation, recruit naïve astrocytes in the neuroinflammation cycle and we propose that such recruitment be mediated by EVs hemichannel (HC) permeability.
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Affiliation(s)
- Christian Memo
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Trieste, Italy
| | - Pietro Parisse
- Nanoinnovation Lab, ELETTRA Synchrotron Light Source, Basovizza, Italy
- CNR-IOM, Basovizza, Italy
| | - Roberta Amoriello
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Trieste, Italy
- Dipartimento di Medicina Sperimentale e Clinica, University of Florence, Firenze, Italy
| | - Maria Pachetti
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Trieste, Italy
| | - Anabela Palandri
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Trieste, Italy
| | - Loredana Casalis
- Nanoinnovation Lab, ELETTRA Synchrotron Light Source, Basovizza, Italy
| | - Clara Ballerini
- Dipartimento di Medicina Sperimentale e Clinica, University of Florence, Firenze, Italy
| | - Laura Ballerini
- Neuroscience Area, International School for Advanced Studies (SISSA/ISAS), Trieste, Italy
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Wu C, Liu S, Zhou L, Chen Z, Yang Q, Cui Y, Chen M, Li L, Ke B, Li C, Yin S. Cellular and Molecular Insights into the Divergence of Neural Stem Cells on Matrigel and Poly-l-lysine Interfaces. ACS APPLIED MATERIALS & INTERFACES 2024; 16:31922-31935. [PMID: 38874539 PMCID: PMC11212020 DOI: 10.1021/acsami.4c02575] [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: 02/14/2024] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 06/15/2024]
Abstract
Poly-l-lysine (PLL) and Matrigel, both classical coating materials for culture substrates in neural stem cell (NSC) research, present distinct interfaces whose effect on NSC behavior at cellular and molecular levels remains ambiguous. Our investigation reveals intriguing disparities: although both PLL and Matrigel interfaces are hydrophilic and feature amine functional groups, Matrigel stands out with lower stiffness and higher roughness. Based on this diversity, Matrigel surpasses PLL, driving NSC adhesion, migration, and proliferation. Intriguingly, PLL promotes NSC differentiation into astrocytes, whereas Matrigel favors neural differentiation and the physiological maturation of neurons. At the molecular level, Matrigel showcases a wider upregulation of genes linked to NSC behavior. Specifically, it enhances ECM-receptor interaction, activates the YAP transcription factor, and heightens glycerophospholipid metabolism, steering NSC proliferation and neural differentiation. Conversely, PLL upregulates genes associated with glial cell differentiation and amino acid metabolism and elevates various amino acid levels, potentially linked to its support for astrocyte differentiation. These distinct transcriptional and metabolic activities jointly shape the divergent NSC behavior on these substrates. This study significantly advances our understanding of substrate regulation on NSC behavior, offering novel insights into optimizing and targeting the application of these surface coating materials in NSC research.
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Affiliation(s)
- Cuiping Wu
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Suru Liu
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Lei Zhou
- Department
of Otorhinolaryngology-Head and Neck Surgery, Zhongshan Hospital Affiliated to Fudan University, Shanghai 200032, China
| | - Zhengnong Chen
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Quanjun Yang
- Department
of Pharmacy, Shanghai Sixth People’s
Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Yaqi Cui
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Ming Chen
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Linpeng Li
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Bingbing Ke
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Chunyan Li
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
| | - Shankai Yin
- Shanghai
Key Laboratory of Sleep Disordered Breathing, Department of Otolaryngology-Head
and Neck Surgery, Otolaryngology Institute of Shanghai Jiao Tong University, Shanghai Sixth People’s Hospital Affiliated
to Shanghai Jiao Tong University School of Medicine, Shanghai 200233, China
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Di Mauro G, Amoriello R, Lozano N, Carnasciali A, Guasti D, Becucci M, Cellot G, Kostarelos K, Ballerini C, Ballerini L. Graphene Oxide Nanosheets Reduce Astrocyte Reactivity to Inflammation and Ameliorate Experimental Autoimmune Encephalomyelitis. ACS NANO 2023; 17:1965-1978. [PMID: 36692902 PMCID: PMC9933621 DOI: 10.1021/acsnano.2c06609] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
In neuroinflammation, astrocytes play multifaceted roles that regulate the neuronal environment. Astrocytes sense and respond to pro-inflammatory cytokines (CKs) and, by a repertoire of intracellular Ca2+ signaling, contribute to disease progression. Therapeutic approaches wish to reduce the overactivation in Ca2+ signaling in inflammatory-reactive astrocytes to restore dysregulated cellular changes. Cell-targeting therapeutics might take advantage by the use of nanomaterial-multifunctional platforms such as graphene oxide (GO). GO biomedical applications in the nervous system involve therapeutic delivery and sensing, and GO flakes were shown to enable interfacing of neuronal and glial membrane dynamics. We exploit organotypic spinal cord cultures and optical imaging to explore Ca2+ changes in astrocytes, and we report, when spinal tissue is exposed to CKs, neuroinflammatory-associated modulation of resident glia. We show the efficacy of GO to revert these dynamic changes in astrocytic reactivity to CKs, and we translate this potential in an animal model of immune-mediated neuroinflammatory disease.
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Affiliation(s)
- Giuseppe Di Mauro
- International
School for Advanced Studies (SISSA/ISAS), 34136Trieste, Italy
| | - Roberta Amoriello
- International
School for Advanced Studies (SISSA/ISAS), 34136Trieste, Italy
- Dipartimento
di Medicina Sperimentale e Clinica, University
of Florence, 50139Florence, Italy
| | - Neus Lozano
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), 08193Barcelona, Spain
| | - Alberto Carnasciali
- Dipartimento
di Medicina Sperimentale e Clinica, University
of Florence, 50139Florence, Italy
| | - Daniele Guasti
- Dipartimento
di Medicina Sperimentale e Clinica, University
of Florence, 50139Florence, Italy
| | - Maurizio Becucci
- Dipartimento
di Chimica “Ugo Schiff”, DICUS, University of Florence, 50139Florence, Italy
| | - Giada Cellot
- International
School for Advanced Studies (SISSA/ISAS), 34136Trieste, Italy
| | - Kostas Kostarelos
- Catalan
Institute of Nanoscience and Nanotechnology (ICN2), 08193Barcelona, Spain
- Nanomedicine
Lab, and Faculty of Biology, Medicine & Health, The National Graphene
Institute, University of Manchester, ManchesterM13 9PL, United Kingdom
| | - Clara Ballerini
- Dipartimento
di Medicina Sperimentale e Clinica, University
of Florence, 50139Florence, Italy
| | - Laura Ballerini
- International
School for Advanced Studies (SISSA/ISAS), 34136Trieste, Italy
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Locus Coeruleus Neurons' Firing Pattern Is Regulated by ERG Voltage-Gated K + Channels. Int J Mol Sci 2022; 23:ijms232315334. [PMID: 36499661 PMCID: PMC9738708 DOI: 10.3390/ijms232315334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2022] [Revised: 11/23/2022] [Accepted: 12/02/2022] [Indexed: 12/12/2022] Open
Abstract
Locus coeruleus (LC) neurons, with their extensive innervations throughout the brain, control a broad range of physiological processes. Several ion channels have been characterized in LC neurons that control intrinsic membrane properties and excitability. However, ERG (ether-à-go-go-related gene) K+ channels that are particularly important in setting neuronal firing rhythms and automaticity have not as yet been discovered in the LC. Moreover, the neurophysiological and pathophysiological roles of ERG channels in the brain remain unclear despite their expression in several structures. By performing immunohistochemical investigations, we found that ERG-1A, ERG-1B, ERG-2 and ERG-3 are highly expressed in the LC neurons of mice. To examine the functional role of ERG channels, current-clamp recordings were performed on mouse LC neurons in brain slices under visual control. ERG channel blockade by WAY-123,398, a class III anti-arrhythmic agent, increased the spontaneous firing activity and discharge irregularity of LC neurons. Here, we have shown the presence of distinct ERG channel subunits in the LC which play an imperative role in modulating neuronal discharge patterns. Thus, we propose that ERG channels are important players behind the changes in, and/or maintenance of, LC firing patterns that are implicated in the generation of different behaviors and in several disorders.
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6
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Effective Perturbations by Phenobarbital on INa, IK(erg), IK(M) and IK(DR) during Pulse Train Stimulation in Neuroblastoma Neuro-2a Cells. Biomedicines 2022; 10:biomedicines10081968. [PMID: 36009515 PMCID: PMC9405590 DOI: 10.3390/biomedicines10081968] [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: 06/12/2022] [Revised: 08/07/2022] [Accepted: 08/09/2022] [Indexed: 11/23/2022] Open
Abstract
Phenobarbital (PHB, Luminal Sodium®) is a medication of the barbiturate and has long been recognized to be an anticonvulsant and a hypnotic because it can facilitate synaptic inhibition in the central nervous system through acting on the γ-aminobutyric acid (GABA) type A (GABAA) receptors. However, to what extent PHB could directly perturb the magnitude and gating of different plasmalemmal ionic currents is not thoroughly explored. In neuroblastoma Neuro-2a cells, we found that PHB effectively suppressed the magnitude of voltage-gated Na+ current (INa) in a concentration-dependent fashion, with an effective IC50 value of 83 µM. The cumulative inhibition of INa, evoked by pulse train stimulation, was enhanced by PHB. However, tefluthrin, an activator of INa, could attenuate PHB-induced reduction in the decaying time constant of INa inhibition evoked by pulse train stimuli. In addition, the erg (ether-à-go-go-related gene)-mediated K+ current (IK(erg)) was also blocked by PHB. The PHB-mediated inhibition on IK(erg) could not be overcome by flumazenil (GABA antagonist) or chlorotoxin (chloride channel blocker). The PHB reduced the recovery of IK(erg) by a two-step voltage protocol with a geometrics-based progression, but it increased the decaying rate of IK(erg), evoked by the envelope-of-tail method. About the M-type K+ currents (IK(M)), PHB caused a reduction of its amplitude, which could not be counteracted by flumazenil or chlorotoxin, and PHB could enhance its cumulative inhibition during pulse train stimulation. Moreover, the magnitude of delayed-rectifier K+ current (IK(DR)) was inhibited by PHB, while the cumulative inhibition of IK(DR) during 10 s of repetitive stimulation was enhanced. Multiple ionic currents during pulse train stimulation were subject to PHB, and neither GABA antagonist nor chloride channel blocker could counteract these PHB-induced reductions. It suggests that these actions might conceivably participate in different functional activities of excitable cells and be independent of GABAA receptors.
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Thalhammer A, Fontanini M, Shi J, Scaini D, Recupero L, Evtushenko A, Fu Y, Pavagada S, Bistrovic-Popov A, Fruk L, Tian B, Ballerini L. Distributed interfacing by nanoscale photodiodes enables single-neuron light activation and sensory enhancement in 3D spinal explants. SCIENCE ADVANCES 2022; 8:eabp9257. [PMID: 35960795 PMCID: PMC9374338 DOI: 10.1126/sciadv.abp9257] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/29/2022] [Indexed: 05/29/2023]
Abstract
Among emerging technologies developed to interface neuronal signaling, engineering electrodes at the nanoscale would yield more precise biodevices opening to progress in neural circuit investigations and to new therapeutic potential. Despite remarkable progress in miniature electronics for less invasive neurostimulation, most nano-enabled, optically triggered interfaces are demonstrated in cultured cells, which precludes the studies of natural neural circuits. We exploit here free-standing silicon-based nanoscale photodiodes to optically modulate single, identified neurons in mammalian spinal cord explants. With near-infrared light stimulation, we show that activating single excitatory or inhibitory neurons differently affects sensory circuits processing in the dorsal horn. We successfully functionalize nano-photodiodes to target single molecules, such as glutamate AMPA receptor subunits, thus enabling light activation of specific synaptic pathways. We conclude that nano-enabled neural interfaces can modulate selected sensory networks with low invasiveness. The use of nanoscale photodiodes can thus provide original perspective in linking neural activity to specific behavioral outcome.
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Affiliation(s)
- Agnes Thalhammer
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Mario Fontanini
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Jiuyun Shi
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Denis Scaini
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
- Elettra Sincrotrone Trieste S.C.p.A., Area Science Park, I-34149 Trieste, Italy
- Basque Foundation for Science, Ikerbasque, Bilbao 48013, Spain
- Universidad del País Vasco (UPV/EHU), Barrio Sarriena s/n, 48940 Leioa, Spain
| | - Luca Recupero
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
| | - Alexander Evtushenko
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Ying Fu
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Suraj Pavagada
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Andrea Bistrovic-Popov
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Ljiljana Fruk
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge, UK
| | - Bozhi Tian
- Department of Chemistry, University of Chicago, Chicago, IL, USA
| | - Laura Ballerini
- International School for Advanced Studies (SISSA), via Bonomea 265, 34136 Trieste, Italy
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Sanchez-Conde FG, Jimenez-Vazquez EN, Auerbach DS, Jones DK. The ERG1 K+ Channel and Its Role in Neuronal Health and Disease. Front Mol Neurosci 2022; 15:890368. [PMID: 35600076 PMCID: PMC9113952 DOI: 10.3389/fnmol.2022.890368] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 04/11/2022] [Indexed: 11/30/2022] Open
Abstract
The ERG1 potassium channel, encoded by KCNH2, has long been associated with cardiac electrical excitability. Yet, a growing body of work suggests that ERG1 mediates physiology throughout the human body, including the brain. ERG1 is a regulator of neuronal excitability, ERG1 variants are associated with neuronal diseases (e.g., epilepsy and schizophrenia), and ERG1 serves as a potential therapeutic target for neuronal pathophysiology. This review summarizes the current state-of-the-field regarding the ERG1 channel structure and function, ERG1’s relationship to the mammalian brain and highlights key questions that have yet to be answered.
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Affiliation(s)
| | - Eric N. Jimenez-Vazquez
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
| | - David S. Auerbach
- Department of Pharmacology, State University of New York Upstate Medical University, Syracuse, NY, United States
- *Correspondence: David S. Auerbach,
| | - David K. Jones
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, United States
- Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI, United States
- David K. Jones,
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The Effectiveness of Isoplumbagin and Plumbagin in Regulating Amplitude, Gating Kinetics, and Voltage-Dependent Hysteresis of erg-mediated K+ Currents. Biomedicines 2022; 10:biomedicines10040780. [PMID: 35453530 PMCID: PMC9029050 DOI: 10.3390/biomedicines10040780] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 03/22/2022] [Accepted: 03/25/2022] [Indexed: 02/04/2023] Open
Abstract
Isoplumbagin (isoPLB, 5-hydroxy-3-methyl-1,4-naphthoquinone), a naturally occurring quinone, has been observed to exercise anti-inflammatory, antimicrobial, and antineoplastic activities. Notably, whether and how isoPLB, plumbagin (PLB), or other related compounds impact transmembrane ionic currents is not entirely clear. In this study, during GH3-cell exposure to isoPLB, the peak and sustained components of an erg (ether-à-go-go related gene)-mediated K+ current (IK(erg)) evoked with long-lasting-step hyperpolarization were concentration-dependently decreased, with a concomitant increase in the decaying time constant of the deactivating current. The presence of isoPLB led to a differential reduction in the peak and sustained components of deactivating IK(erg) with effective IC50 values of 18.3 and 2.4 μM, respectively, while the KD value according to the minimum binding scheme was estimated to be 2.58 μM. Inhibition by isoPLB of IK(erg) was not reversed by diazoxide; however, further addition of isoPLB, during the continued exposure to 4,4′-dithiopyridine, did not suppress IK(erg) further. The recovery of IK(erg) by a two-step voltage pulse with a geometric progression was slowed in the presence of isoPLB, and the decaying rate of IK(erg) activated by the envelope-of-tail method was increased in its presence. The strength of the IK(erg) hysteresis in response to an inverted isosceles-triangular ramp pulse was diminished by adding isoPLB. A mild inhibition of the delayed-rectifier K+ current (IK(DR)) produced by the presence of isoPLB was seen in GH3 cells, while minimal changes in the magnitude of the voltage-gated Na+ current were demonstrated in its presence. Moreover, the IK(erg) identified in MA-10 Leydig tumor cells was blocked by adding isoPLB. Therefore, the effects of isoPLB or PLB on ionic currents (e.g., IK(erg) and IK(DR)) demonstrated herein would be upstream of our previously reported perturbations on mitochondrial morphogenesis or respiration. Taken together, the perturbations of ionic currents by isoPLB or PLB demonstrated herein are likely to contribute to the underlying mechanism through which they, or other structurally similar compounds, result in adjustments in the functional activities of different neoplastic cells (e.g., GH3 and MA-10 cells), presuming that similar in vivo observations occur.
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10
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Panattoni G, Amoriello R, Memo C, Thalhammer A, Ballerini C, Ballerini L. Diverse inflammatory threats modulate astrocytes Ca 2+ signaling via connexin43 hemichannels in organotypic spinal slices. Mol Brain 2021; 14:159. [PMID: 34696792 PMCID: PMC8547100 DOI: 10.1186/s13041-021-00868-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 10/15/2021] [Indexed: 02/07/2023] Open
Abstract
Neuroinflammation is an escalation factor shared by a vast range of central nervous system (CNS) pathologies, from neurodegenerative diseases to neuropsychiatric disorders. CNS immune status emerges by the integration of the responses of resident and not resident cells, leading to alterations in neural circuits functions. To explore spinal cord astrocyte reactivity to inflammatory threats we focused our study on the effects of local inflammation in a controlled micro-environment, the organotypic spinal slices, developed from the spinal cord of mouse embryos. These organ cultures represent a complex in vitro model where sensory-motor cytoarchitecture, synaptic properties and spinal cord resident cells, are retained in a 3D fashion and we recently exploit these cultures to model two diverse immune conditions in the CNS, involving different inflammatory networks and products. Here, we specifically focus on the tuning of calcium signaling in astrocytes by these diverse types of inflammation and we investigate the mechanisms which modulate intracellular calcium release and its spreading among astrocytes in the inflamed environment. Organotypic spinal cord slices are cultured for two or three weeks in vitro (WIV) and exposed for 6 h to a cocktail of cytokines (CKs), composed by tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1 β) and granulocyte macrophage-colony stimulating factor (GM-CSF), or to lipopolysaccharide (LPS). By live calcium imaging of the ventral horn, we document an increase in active astrocytes and in the occurrence of spontaneous calcium oscillations displayed by these cells when exposed to each inflammatory threat. Through several pharmacological treatments, we demonstrate that intracellular calcium sources and the activation of connexin 43 (Cx43) hemichannels have a pivotal role in increasing calcium intercellular communication in both CKs and LPS conditions, while the Cx43 gap junction communication is apparently reduced by the inflammatory treatments.
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Affiliation(s)
- Giulia Panattoni
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Roberta Amoriello
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.,Dipartimento di Medicina Sperimentale e Clinica, University of Florence, 50139, Florence, Italy
| | - Christian Memo
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Agnes Thalhammer
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Clara Ballerini
- Dipartimento di Medicina Sperimentale e Clinica, University of Florence, 50139, Florence, Italy.
| | - Laura Ballerini
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.
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11
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Secomandi N, Franceschi Biagioni A, Kostarelos K, Cellot G, Ballerini L. Thin graphene oxide nanoflakes modulate glutamatergic synapses in the amygdala cultured circuits: Exploiting synaptic approaches to anxiety disorders. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2020; 26:102174. [DOI: 10.1016/j.nano.2020.102174] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/18/2020] [Indexed: 11/26/2022]
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12
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Buntschu S, Tscherter A, Heidemann M, Streit J. Critical Components for Spontaneous Activity and Rhythm Generation in Spinal Cord Circuits in Culture. Front Cell Neurosci 2020; 14:81. [PMID: 32410961 PMCID: PMC7198714 DOI: 10.3389/fncel.2020.00081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/19/2020] [Indexed: 11/23/2022] Open
Abstract
Neuronal excitability contributes to rhythm generation in central pattern generating networks (CPGs). In spinal cord CPGs, such intrinsic excitability partly relies on persistent sodium currents (INaP), whereas respiratory CPGs additionally depend on calcium-activated cation currents (ICAN). Here, we investigated the contributions of INaP and ICAN to spontaneous rhythm generation in neuronal networks of the spinal cord and whether they mainly involve Hb9 neurons. We used cultures of ventral and transverse slices from the E13-14 embryonic rodent lumbar spinal cord on multielectrode arrays (MEAs). All cultures showed spontaneous bursts of network activity. Blocking synaptic excitation with the AMPA receptor antagonist CNQX suppressed spontaneous network bursts and left asynchronous intrinsic activity at about 30% of the electrodes. Such intrinsic activity was completely blocked at all electrodes by both the INaP blocker riluzole as well as by the ICAN blocker flufenamic acid (FFA) and the more specific TRPM4 channel antagonist 9-phenanthrol. All three antagonists also suppressed spontaneous bursting completely and strongly reduced stimulus-evoked bursts. Also, FFA reduced repetitive spiking that was induced in single neurons by injection of depolarizing current pulses to few spikes. Other antagonists of unspecific cation currents or calcium currents had no suppressing effects on either intrinsic activity (gadolinium chloride) or spontaneous bursting (the TRPC channel antagonists clemizole and ML204 and the T channel antagonist TTA-P2). Combined patch-clamp and MEA recordings showed that Hb9 interneurons were activated by network bursts but could not initiate them. Together these findings suggest that both INaP through Na+-channels and ICAN through putative TRPM4 channels contribute to spontaneous intrinsic and repetitive spiking in spinal cord neurons and thereby to the generation of network bursts.
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Affiliation(s)
| | | | | | - Jürg Streit
- Department of Physiology, University of Bern, Bern, Switzerland
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13
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Rauti R, Secomandi N, Martín C, Bosi S, Severino FPU, Scaini D, Prato M, Vázquez E, Ballerini L. Tuning Neuronal Circuit Formation in 3D Polymeric Scaffolds by Introducing Graphene at the Bio/Material Interface. ACTA ACUST UNITED AC 2020; 4:e1900233. [DOI: 10.1002/adbi.201900233] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 01/19/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Rossana Rauti
- International School for Advanced Studies (SISSA/ISAS) Trieste 34136 Italy
| | - Nicola Secomandi
- International School for Advanced Studies (SISSA/ISAS) Trieste 34136 Italy
- Instituto Regional de Investigación Científica Aplicada (IRICA) Universidad de Castilla‐La Mancha Avda Camilo José Cela 13071 Ciudad Real Spain
| | - Cristina Martín
- Department of Chemical and Pharmaceutical Sciences Università degli Studi di Trieste Via Licio Giorgieri 1 Trieste 34127 Italy
- Carbon Bionanotechnology Group CIC biomaGUNE Paseo Miramón 182 San Sebastián 20014 Guipúzcoa Spain
| | - Susanna Bosi
- Carbon Bionanotechnology Group CIC biomaGUNE Paseo Miramón 182 San Sebastián 20014 Guipúzcoa Spain
| | | | - Denis Scaini
- International School for Advanced Studies (SISSA/ISAS) Trieste 34136 Italy
- Basque Foundation for Science Ikerbasque Bilbao 48013 Spain
| | - Maurizio Prato
- Carbon Bionanotechnology Group CIC biomaGUNE Paseo Miramón 182 San Sebastián 20014 Guipúzcoa Spain
- Faculty of Chemical Science and Technology Universidad de Castilla‐La Mancha 13071 Ciudad Real Spain
| | - Ester Vázquez
- Department of Chemical and Pharmaceutical Sciences Università degli Studi di Trieste Via Licio Giorgieri 1 Trieste 34127 Italy
| | - Laura Ballerini
- International School for Advanced Studies (SISSA/ISAS) Trieste 34136 Italy
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14
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Shults NV, Rybka V, Suzuki YJ, Brelidze TI. Increased Smooth Muscle Kv11.1 Channel Expression in Pulmonary Hypertension and Protective Role of Kv11.1 Channel Blocker Dofetilide. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:48-56. [PMID: 31839145 PMCID: PMC6943378 DOI: 10.1016/j.ajpath.2019.09.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2019] [Revised: 09/05/2019] [Accepted: 09/17/2019] [Indexed: 01/08/2023]
Abstract
Kv11.1 potassium channels are essential for heart repolarization. Prescription medication that blocks Kv11.1 channels lengthens the ventricular action potential and causes cardiac arrhythmias. Surprisingly little is known about the Kv11.1 channel expression and function in the lung tissue. Here we report that Kv11.1 channels were abundantly expressed in the large pulmonary arteries (PAs) of healthy lung tissues from humans and rats. Kv11.1 channel expression was increased in the lungs of humans affected by chronic obstructive pulmonary disease-associated pulmonary hypertension and in the lungs of rats with pulmonary arterial hypertension (PAH). In healthy lung tissues from humans and rats, Kv11.1 channels were confined to the large PAs. In humans with chronic obstructive pulmonary disease-associated pulmonary hypertension and in rats with PAH, Kv11.1 channels were expressed in both the large and small PAs. The increase in Kv11.1 channel expression closely followed the time-course of the development of pulmonary vascular remodeling in PAH rats. Treatment of PAH rats with dofetilide, an Kv11.1 channel blocker approved by the US Food and Drug Administration for use in the treatment of arrythmia, inhibited PAH-associated pulmonary vascular remodeling. Taken together, the findings from this study uncovered a novel role of Kv11.1 channels in lung function and their potential as new drug targets in the treatment of pulmonary hypertension. The protective effect of dofetilide raises the possibility of repurposing this antiarrhythmic drug for the treatment of patients with pulmonary hypertension.
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MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Animals
- Arrhythmias, Cardiac/etiology
- Arrhythmias, Cardiac/pathology
- Arrhythmias, Cardiac/prevention & control
- Case-Control Studies
- ERG1 Potassium Channel/antagonists & inhibitors
- ERG1 Potassium Channel/metabolism
- Female
- Follow-Up Studies
- Humans
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Phenethylamines/pharmacology
- Potassium Channel Blockers/pharmacology
- Prognosis
- Pulmonary Arterial Hypertension/complications
- Pulmonary Arterial Hypertension/metabolism
- Pulmonary Arterial Hypertension/pathology
- Rats, Sprague-Dawley
- Sulfonamides/pharmacology
- Vascular Remodeling/drug effects
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Affiliation(s)
- Nataliia V Shults
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia
| | - Vladyslava Rybka
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia
| | - Yuichiro J Suzuki
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia
| | - Tinatin I Brelidze
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, District of Columbia.
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15
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Giacco V, Panattoni G, Medelin M, Bonechi E, Aldinucci A, Ballerini C, Ballerini L. Cytokine inflammatory threat, but not LPS one, shortens GABAergic synaptic currents in the mouse spinal cord organotypic cultures. J Neuroinflammation 2019; 16:127. [PMID: 31238967 PMCID: PMC6593520 DOI: 10.1186/s12974-019-1519-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Accepted: 06/11/2019] [Indexed: 01/02/2023] Open
Abstract
Background Synaptic dysfunction, named synaptopathy, due to inflammatory status of the central nervous system (CNS) is a recognized factor potentially underlying both motor and cognitive dysfunctions in neurodegenerative diseases. To gain knowledge on the mechanistic interplay between local inflammation and synapse changes, we compared two diverse inflammatory paradigms, a cytokine cocktail (CKs; IL-1β, TNF-α, and GM-CSF) and LPS, and their ability to tune GABAergic current duration in spinal cord cultured circuits. Methods We exploit spinal organotypic cultures, single-cell electrophysiology, immunocytochemistry, and confocal microscopy to explore synaptic currents and resident neuroglia reactivity upon CK or LPS incubation. Results Local inflammation in slice cultures induced by CK or LPS stimulations boosts network activity; however, only CKs specifically reduced GABAergic current duration. We pharmacologically investigated the contribution of GABAAR α-subunits and suggested that a switch of GABAAR α1-subunit might have induced faster GABAAR decay time, weakening the inhibitory transmission. Conclusions Lower GABAergic current duration could contribute to providing an aberrant excitatory transmission critical for pre-motor circuit tasks and represent a specific feature of a CK cocktail able to mimic an inflammatory reaction that spreads in the CNS. Our results describe a selective mechanism that could be triggered during specific inflammatory stress. Electronic supplementary material The online version of this article (10.1186/s12974-019-1519-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vincenzo Giacco
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.,Present address: Wolfson Centre for Age Related Disease, King's College London, Guy's Campus, London, SE1 1UL, UK
| | - Giulia Panattoni
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - Manuela Medelin
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy
| | - Elena Bonechi
- Department NEUROFARBA, University of Florence, 50139, Florence, Italy
| | | | - Clara Ballerini
- Dipartimento di Medicina Sperimentale e Clinica, University of Florence, 50139, Florence, Italy.
| | - Laura Ballerini
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.
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16
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So EC, Foo NP, Ko SY, Wu SN. Bisoprolol, Known to Be a Selective β₁-Receptor Antagonist, Differentially but Directly Suppresses I K(M) and I K(erg) in Pituitary Cells and Hippocampal Neurons. Int J Mol Sci 2019; 20:E657. [PMID: 30717422 PMCID: PMC6386942 DOI: 10.3390/ijms20030657] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Revised: 01/27/2019] [Accepted: 01/30/2019] [Indexed: 12/27/2022] Open
Abstract
Bisoprolol (BIS) is a selective antagonist of β₁ adrenergic receptors. We examined the effects of BIS on M-type K⁺ currents (IK(M)) or erg-mediated K⁺ currents (IK(erg)) in pituitary GH3, R1220 cells, and hippocampal mHippoE-14 cells. As GH₃ cells were exposed to BIS, amplitude of IK(M) was suppressed with an IC50 value of 1.21 μM. The BIS-induced suppression of IK(M) amplitude was not affected by addition of isoproterenol or ractopamine, but attenuated by flupirtine or ivabradine. In cell-attached current, BIS decreased the open probability of M-type K⁺ (KM) channels, along with decreased mean opening time of the channel. BIS decreased IK(erg) amplitude with an IC50 value of 6.42 μM. Further addition of PD-118057 attenuated BIS-mediated inhibition of IK(erg). Under current-clamp conditions, BIS depolarization increased the firing of spontaneous action potentials in GH₃ cells; addition of flupirtine, but not ractopamine, reversed BIS-induced firing rate. In R1220 cells, BIS suppressed IK(M); subsequent application of ML-213(Kv7.2 channel activator) reversed BIS-induced suppression of the current. In hippocampal mHippoE-14 neurons, BIS inhibited IK(M) to a greater extent compared to its depressant effect on IK(erg). This demonstrated that in pituitary cells and hippocampal neurons the presence of BIS is capable of directly and differentially suppressing IK(M) and IK(erg), despite its antagonism of β₁-adrenergic receptors.
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Affiliation(s)
- Edmund Cheung So
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan.
- Department of Anesthesia, China Medical University, Taichung 40402, Taiwan.
- Graduate Institute of Medical Sciences, Chang Jung Christian University, Tainan 71101, Taiwan.
| | - Ning-Ping Foo
- Department of Anesthesia, An Nan Hospital, China Medical University, Tainan 70965, Taiwan.
- Graduate Institute of Medical Sciences, Chang Jung Christian University, Tainan 71101, Taiwan.
- Department of Emergency Medicine, An Nan Hospital, China Medical University, Tainan 70965, Taiwan.
| | - Shun Yao Ko
- Graduate Institute of Medical Sciences, Chang Jung Christian University, Tainan 71101, Taiwan.
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan.
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan.
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17
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Musto M, Rauti R, Rodrigues AF, Bonechi E, Ballerini C, Kostarelos K, Ballerini L. 3D Organotypic Spinal Cultures: Exploring Neuron and Neuroglia Responses Upon Prolonged Exposure to Graphene Oxide. Front Syst Neurosci 2019; 13:1. [PMID: 30733671 PMCID: PMC6354065 DOI: 10.3389/fnsys.2019.00001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/03/2019] [Indexed: 11/13/2022] Open
Abstract
Graphene-based nanomaterials are increasingly engineered as components of biosensors, interfaces or drug delivery platforms in neuro-repair strategies. In these developments, the mostly used derivative of graphene is graphene oxide (GO). To tailor the safe development of GO nanosheets, we need to model in vitro tissue responses, and in particular the reactivity of microglia, a sub-population of neuroglia that acts as the first active immune response, when challenged by GO. Here, we investigated central nervous system (CNS) tissue reactivity upon long-term exposure to GO nanosheets in 3D culture models. We used the mouse organotypic spinal cord cultures, ideally suited for studying long-term interference with cues delivered at controlled times and concentrations. In cultured spinal segments, the normal presence, distribution and maturation of anatomically distinct classes of neurons and resident neuroglial cells are preserved. Organotypic explants were developed for 2 weeks embedded in fibrin glue alone or presenting GO nanosheets at 10, 25 and 50 μg/mL. We addressed the impact of such treatments on premotor synaptic activity monitored by patch clamp recordings of ventral interneurons. We investigated by immunofluorescence and confocal microscopy the accompanying glial responses to GO exposure, focusing on resident microglia, tested in organotypic spinal slices and in isolated neuroglia cultures. Our results suggest that microglia reactivity to accumulation of GO flakes, maybe due to active phagocytosis, may trim down synaptic activity, although in the absence of an effective activation of inflammatory response and in the absence of neuronal cell death.
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Affiliation(s)
- Mattia Musto
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Rossana Rauti
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Artur Filipe Rodrigues
- Nanomedicine Lab, Faculty of Biology, Medicine & Health and National Graphene Institute, University of Manchester, Manchester, United Kingdom
| | - Elena Bonechi
- Department NEUROFARBA, University of Florence, Florence, Italy
| | - Clara Ballerini
- Laboratory of Neuroimmunology, Dipartimento di Medicina Sperimentale e Clinica, University of Firenze, Firenze, Italy
| | - Kostas Kostarelos
- Nanomedicine Lab, Faculty of Biology, Medicine & Health and National Graphene Institute, University of Manchester, Manchester, United Kingdom
| | - Laura Ballerini
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Trieste, Italy
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18
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Pampaloni NP, Lottner M, Giugliano M, Matruglio A, D'Amico F, Prato M, Garrido JA, Ballerini L, Scaini D. Single-layer graphene modulates neuronal communication and augments membrane ion currents. NATURE NANOTECHNOLOGY 2018; 13:755-764. [PMID: 29892019 DOI: 10.1038/s41565-018-0163-6] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 05/08/2018] [Indexed: 05/24/2023]
Abstract
The use of graphene-based materials to engineer sophisticated biosensing interfaces that can adapt to the central nervous system requires a detailed understanding of how such materials behave in a biological context. Graphene's peculiar properties can cause various cellular changes, but the underlying mechanisms remain unclear. Here, we show that single-layer graphene increases neuronal firing by altering membrane-associated functions in cultured cells. Graphene tunes the distribution of extracellular ions at the interface with neurons, a key regulator of neuronal excitability. The resulting biophysical changes in the membrane include stronger potassium ion currents, with a shift in the fraction of neuronal firing phenotypes from adapting to tonically firing. By using experimental and theoretical approaches, we hypothesize that the graphene-ion interactions that are maximized when single-layer graphene is deposited on electrically insulating substrates are crucial to these effects.
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Affiliation(s)
| | - Martin Lottner
- Walter Schottky Institut and Physik-Department, Technische Universität München, Garching, Germany
| | - Michele Giugliano
- Molecular, Cellular, and Network Excitability, Department of Biomedical Sciences, Universiteit Antwerp, Antwerp, Belgium
- Department of Computer Science, University of Sheffield, Sheffield, UK
- Lab of Neural Microcircuitry, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Alessia Matruglio
- CNR-IOM-Istituto Officina dei Materiali, Trieste, Italy
- CERIC-ERIC (Central European Research Infrastructure Consortium), Trieste, Italy
| | | | - Maurizio Prato
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste, Italy
- Nanobiotechnology Laboratory, CIC biomaGUNE, San Sebastiàn, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Josè Antonio Garrido
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, Spain.
- ICREA3, Barcelona, Spain.
| | - Laura Ballerini
- International School for Advanced Studies (SISSA), Trieste, Italy.
| | - Denis Scaini
- International School for Advanced Studies (SISSA), Trieste, Italy.
- Elettra Sincrotrone Trieste S.C.p.A., Trieste, Italy.
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19
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Medelin M, Giacco V, Aldinucci A, Castronovo G, Bonechi E, Sibilla A, Tanturli M, Torcia M, Ballerini L, Cozzolino F, Ballerini C. Bridging pro-inflammatory signals, synaptic transmission and protection in spinal explants in vitro. Mol Brain 2018; 11:3. [PMID: 29334986 PMCID: PMC5769440 DOI: 10.1186/s13041-018-0347-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 01/04/2018] [Indexed: 01/30/2023] Open
Abstract
Multiple sclerosis is characterized by tissue atrophy involving the brain and the spinal cord, where reactive inflammation contributes to the neurodegenerative processes. Recently, the presence of synapse alterations induced by the inflammatory responses was suggested by experimental and clinical observations, in experimental autoimmune encephalomyelitis mouse model and in patients, respectively. Further knowledge on the interplay between pro-inflammatory agents, neuroglia and synaptic dysfunction is crucial to the design of unconventional protective molecules. Here we report the effects, on spinal cord circuits, of a cytokine cocktail that partly mimics the signature of T lymphocytes sub population Th1. In embryonic mouse spinal organ-cultures, containing neuronal cells and neuroglia, cytokines induced inflammatory responses accompanied by a significant increase in spontaneous synaptic activity. We suggest that cytokines specifically altered signal integration in spinal networks by speeding the decay of GABAA responses. This hypothesis is supported by the finding that synapse protection by a non-peptidic NGF mimetic molecule prevented both the changes in the time course of GABA events and in network activity that were left unchanged by the cytokine production from astrocytes and microglia present in the cultured tissue. In conclusion, we developed an important tool for the study of synaptic alterations induced by inflammation, that takes into account the role of neuronal and not neuronal resident cells.
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Affiliation(s)
- M Medelin
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy.,International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - V Giacco
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy
| | - A Aldinucci
- Department NEUROFARBA, University of Florence, 50139, Florence, Italy
| | - G Castronovo
- Department of DSBSC, University of Florence, 50134, Florence, Italy
| | - E Bonechi
- Department NEUROFARBA, University of Florence, 50139, Florence, Italy
| | - A Sibilla
- Department NEUROFARBA, University of Florence, 50139, Florence, Italy
| | - M Tanturli
- Department of DSBSC, University of Florence, 50134, Florence, Italy
| | - M Torcia
- Department of DMSC, University of Florence, 50134, Florence, Italy
| | - L Ballerini
- International School for Advanced Studies (SISSA/ISAS), 34136, Trieste, Italy.
| | - F Cozzolino
- Department of DSBSC, University of Florence, 50134, Florence, Italy
| | - C Ballerini
- Department NEUROFARBA, University of Florence, 50139, Florence, Italy.
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20
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Huang CS, Wang GH, Tai CH, Hu CC, Yang YC. Antiarrhythmics cure brain arrhythmia: The imperativeness of subthalamic ERG K + channels in parkinsonian discharges. SCIENCE ADVANCES 2017; 3:e1602272. [PMID: 28508055 PMCID: PMC5425237 DOI: 10.1126/sciadv.1602272] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 03/15/2017] [Indexed: 06/07/2023]
Abstract
ERG K+ channels have long been known to play a crucial role in shaping cardiac action potentials and, thus, appropriate heart rhythms. The functional role of ERG channels in the central nervous system, however, remains elusive. We demonstrated that ERG channels exist in subthalamic neurons and have similar gating characteristics to those in the heart. ERG channels contribute crucially not only to the setting of membrane potential and, consequently, the firing modes, but also to the configuration of burst discharges and, consequently, the firing frequency and automaticity of the subthalamic neurons. Moreover, modulation of subthalamic discharges via ERG channels effectively modulates locomotor behaviors. ERG channel inhibitors ameliorate parkinsonian symptoms, whereas enhancers render normal animals hypokinetic. Thus, ERG K+ channels could be vital to the regulation of both cardiac and neuronal rhythms and may constitute an important pathophysiological basis and pharmacotherapeutic target for the growing list of neurological disorders related to "brain arrhythmias."
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Affiliation(s)
- Chen-Syuan Huang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Guan-Hsun Wang
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- School of Medicine, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Chun-Hwei Tai
- Department of Neurology, National Taiwan University Hospital, Taipei, Taiwan
| | - Chun-Chang Hu
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Ya-Chin Yang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
- Neuroscience Research Center, Chang Gung Memorial Hospital, Linkou Medical Center, Tao-Yuan, Taiwan
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21
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Gentile S. hERG1 potassium channel in cancer cells: a tool to reprogram immortality. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 45:649-655. [PMID: 27649700 DOI: 10.1007/s00249-016-1169-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 07/21/2016] [Accepted: 08/30/2016] [Indexed: 12/12/2022]
Abstract
It has been well established that changes in ion fluxes across cellular membranes as a function of time is fundamental in maintaining cellular homeostasis of every living cell. Consequently, dysregulation of ion channels activity is a critical event in pathological conditions of several tissues, including cancer. Nevertheless, the role of ion channels in cancer biology is still not well understood and very little is known about the possible therapeutic opportunities offered by the use of the vast collection of drugs that target ion channels. In this review, we focus on the recent advances in understanding the role of the voltage-gated hERG1 potassium channel in cancer and on the effects of pharmacologic manipulation of the hERG1 in cancer cells aiming to provide insights into the biochemical signaling and cellular processes that are altered by using these drugs.
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22
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Usmani S, Aurand ER, Medelin M, Fabbro A, Scaini D, Laishram J, Rosselli FB, Ansuini A, Zoccolan D, Scarselli M, De Crescenzi M, Bosi S, Prato M, Ballerini L. 3D meshes of carbon nanotubes guide functional reconnection of segregated spinal explants. SCIENCE ADVANCES 2016; 2:e1600087. [PMID: 27453939 PMCID: PMC4956187 DOI: 10.1126/sciadv.1600087] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/22/2016] [Indexed: 05/15/2023]
Abstract
In modern neuroscience, significant progress in developing structural scaffolds integrated with the brain is provided by the increasing use of nanomaterials. We show that a multiwalled carbon nanotube self-standing framework, consisting of a three-dimensional (3D) mesh of interconnected, conductive, pure carbon nanotubes, can guide the formation of neural webs in vitro where the spontaneous regrowth of neurite bundles is molded into a dense random net. This morphology of the fiber regrowth shaped by the 3D structure supports the successful reconnection of segregated spinal cord segments. We further observed in vivo the adaptability of these 3D devices in a healthy physiological environment. Our study shows that 3D artificial scaffolds may drive local rewiring in vitro and hold great potential for the development of future in vivo interfaces.
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Affiliation(s)
- Sadaf Usmani
- International School for Advanced Studies (SISSA/ISAS), Trieste 34136, Italy
| | - Emily Rose Aurand
- Department of Life Sciences, University of Trieste, Trieste 34127, Italy
| | - Manuela Medelin
- Department of Life Sciences, University of Trieste, Trieste 34127, Italy
| | - Alessandra Fabbro
- Department of Life Sciences, University of Trieste, Trieste 34127, Italy
| | - Denis Scaini
- Department of Life Sciences, University of Trieste, Trieste 34127, Italy
- NanoInnovation Laboratory, ELETTRA Synchrotron Light Source, Trieste 34149, Italy
| | - Jummi Laishram
- Department of Life Sciences, University of Trieste, Trieste 34127, Italy
| | | | - Alessio Ansuini
- International School for Advanced Studies (SISSA/ISAS), Trieste 34136, Italy
| | - Davide Zoccolan
- International School for Advanced Studies (SISSA/ISAS), Trieste 34136, Italy
| | - Manuela Scarselli
- Department of Physics, University of Rome Tor Vergata, Rome 00173, Italy
| | | | - Susanna Bosi
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste 34127, Italy
| | - Maurizio Prato
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Trieste 34127, Italy
- Carbon Nanobiotechnology Laboratory, CIC biomaGUNE, Paseo de Miramón 182, 20009 Donostia–San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48013 Bilbao, Spain
- Corresponding author. (L.B.); (M.P.)
| | - Laura Ballerini
- International School for Advanced Studies (SISSA/ISAS), Trieste 34136, Italy
- Corresponding author. (L.B.); (M.P.)
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23
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Medelin M, Rancic V, Cellot G, Laishram J, Veeraraghavan P, Rossi C, Muzio L, Sivilotti L, Ballerini L. Altered development in GABA co-release shapes glycinergic synaptic currents in cultured spinal slices of the SOD1(G93A) mouse model of amyotrophic lateral sclerosis. J Physiol 2016; 594:3827-40. [PMID: 27098371 DOI: 10.1113/jp272382] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/07/2016] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Increased environmental risk factors in conjunction with genetic susceptibility have been proposed with respect to the remarkable variations in mortality in amyotrophic lateral sclerosis (ALS). In vitro models allow the investigation of the genetically modified counter-regulator of motoneuron toxicity and may help in addressing ALS therapy. Spinal organotypic slice cultures from a mutant form of human superoxide dismutase 1 (SOD1G93A) mouse model of ALS allow the detection of altered glycinergic inhibition in spinal microcircuits. This altered inhibition improved spinal cord excitability, affecting motor outputs in early SOD1(G93A) pathogenesis. ABSTRACT Amyotrophic lateral sclerosis (ALS) is a fatal, adult-onset neurological disease characterized by a progressive degeneration of motoneurons (MNs). In a previous study, we developed organotypic spinal cultures from an ALS mouse model expressing a mutant form of human superoxide dismutase 1 (SOD1(G93A) ). We reported the presence of a significant synaptic rearrangement expressed by these embryonic cultured networks, which may lead to the altered development of spinal synaptic signalling, which is potentially linked to the adult disease phenotype. Recent studies on the same ALS mouse model reported a selective loss of glycinergic innervation in cultured MNs, suggestive of a contribution of synaptic inhibition to MN dysfunction and degeneration. In the present study, we further exploit organotypic cultures from wild-type and SOD1(G93A) mice to investigate the development of glycine-receptor-mediated synaptic currents recorded from the interneurons of the premotor ventral circuits. We performed single cell electrophysiology, immunocytochemistry and confocal microscopy and suggest that GABA co-release may speed the decay of glycine responses altering both temporal precision and signal integration in SOD1(G93A) developing networks at the postsynaptic site. Our hypothesis is supported by the finding of an increased MN bursting activity in immature SOD1(G93A) spinal cords and by immunofluorescence microscopy detection of a longer persistence of GABA in SOD1(G93A) glycinergic terminals in cultured and ex vivo spinal slices.
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Affiliation(s)
- Manuela Medelin
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Vladimir Rancic
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Giada Cellot
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Jummi Laishram
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | | | - Chiara Rossi
- Neuroimmunology Unit, Division of Neuroscience, Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, Milan, Italy
| | - Luca Muzio
- Neuroimmunology Unit, Division of Neuroscience, Institute of Experimental Neurology (INSPE), San Raffaele Scientific Institute, Milan, Italy
| | - Lucia Sivilotti
- Department of Neuroscience, Physiology and Pharmacology, University College London (UCL), London, UK
| | - Laura Ballerini
- Department of Life Sciences, University of Trieste, Trieste, Italy.,International School for Advanced Studies (SISSA/ISAS), Trieste, Italy
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24
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Weimer I, Worek F, Seeger T, Thiermann H, Eckle VS, Grasshoff C, Antkowiak B. Self-regeneration of neuromuscular function following soman and VX poisoning in spinal cord-skeletal muscle cocultures. Toxicol Lett 2016; 244:149-153. [PMID: 26256036 DOI: 10.1016/j.toxlet.2015.08.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 07/31/2015] [Accepted: 08/04/2015] [Indexed: 12/21/2022]
Abstract
Aside from nerve agents, various highly toxic pesticides belong to the group of organophosphorus (OP) compounds, thereby causing a large number of intoxications every year. Unfortunately, there are still shortcomings in the current treatment for OP poisoning and research on novel therapeutic options is restricted in several aspects. In this study we investigated the suitability of organotypic cocultures for pharmacological in vitro studies involving OP compounds. These slice cultures are derived from murine spinal cord and muscle tissue forming functional neuromuscular synapses, which trigger spontaneous contractions of muscle fibers. Using video microscopy to quantify muscle activity, we assessed the viability of cocultures after exposure to soman and VX, and the associated loss and recovery of neuromuscular function. Antidotal treatment was not provided. The application of nerve agents led to an almost complete loss of muscle activity. However, cell cultures regained equivalent muscular function to the control situation three and seven days after intoxication. In summary, the tested in vitro system could be a promising tool for the investigation of long term effects and therapeutic options for OP poisoning.
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Affiliation(s)
- Isabel Weimer
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany; Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany.
| | - Franz Worek
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Thomas Seeger
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Horst Thiermann
- Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany
| | - Veit-Simon Eckle
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany
| | - Christian Grasshoff
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany
| | - Bernd Antkowiak
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Waldhoernlestrasse 22, 72072 Tuebingen, Germany; Werner-Reichardt-Centre for Integrative Neuroscience, Eberhard-Karls-University, 72076 Tuebingen, Germany
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25
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Tomuschat C, O'Donnell AM, Coyle D, Puri P. Reduced expression of voltage-gated Kv11.1 (hERG) K(+) channels in aganglionic colon in Hirschsprung's disease. Pediatr Surg Int 2016; 32:9-16. [PMID: 26519040 DOI: 10.1007/s00383-015-3807-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/09/2015] [Indexed: 01/29/2023]
Abstract
PURPOSE The pathophysiology of Hirschsprung's disease (HSCR) is not entirely understood. There is no clear explanation for the occurrence of the spastic or tonically contracted aganglionic segment of bowel. Kv11.1 (hERG) channels play a critical role in the regulation of the resting membrane potential as well as affecting either the force or frequency of contraction of smooth muscles. We designed this study to investigate the expression and distribution of hERG channels in the normal colon and the colon of patients with HSCR. METHODS We investigated hERG protein expression in both the ganglionic and aganglionic regions of HSCR patients (n = 10) versus normal control colon (n = 10). Protein distribution was assessed using immunofluorescence and confocal microscopy. Gene and protein expressions were quantified using real-time polymerase chain reaction, western blot analysis and densitometry. RESULTS Confocal microscopy of the normal colon revealed strong hERG channel expression in interstitial cells of Cajal, platelet-derived growth factor-alpha receptor- (PDGFRα(+)) positive cells and enteric neurons. hERG expression was markedly decreased in aganglionic bowel, whereas colonic hERG gene expression levels were significantly decreased in aganglionic compared to ganglionic bowel and controls (p < 0.05). Western blotting revealed decreased colonic hERG protein expression in aganglionic HSCR specimens compared to controls. CONCLUSIONS We demonstrate, for the first time, the expression and distribution of hERG channels in the human colon. The decreased expression of hERG in the aganglionic colon may be responsible for the increased tone in the aganglionic narrow spastic segment of bowel.
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Affiliation(s)
- Christian Tomuschat
- National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland
| | - Anne Marie O'Donnell
- National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland
| | - David Coyle
- National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland
| | - Prem Puri
- National Children's Research Centre, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
- Conway Institute of Biomedical Research, School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.
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26
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Arcangeli A, Becchetti A. Novel perspectives in cancer therapy: Targeting ion channels. Drug Resist Updat 2015; 21-22:11-9. [DOI: 10.1016/j.drup.2015.06.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 06/24/2015] [Accepted: 06/27/2015] [Indexed: 01/04/2023]
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27
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Mitcheson J, Arcangeli A. The Therapeutic Potential of hERG1 K+ Channels for Treating Cancer and Cardiac Arrhythmias. ION CHANNEL DRUG DISCOVERY 2014. [DOI: 10.1039/9781849735087-00258] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
hERG potassium channels present pharmacologists and medicinal chemists with a dilemma. On the one hand hERG is a major reason for drugs being withdrawn from the market because of drug induced long QT syndrome and the associated risk of inducing sudden cardiac death, and yet hERG blockers are still widely used in the clinic to treat cardiac arrhythmias. Moreover, in the last decade overwhelming evidence has been provided that hERG channels are aberrantly expressed in cancer cells and that they contribute to tumour cell proliferation, resistance to apoptosis, and neoangiogenesis. Here we provide an overview of the properties of hERG channels and their role in excitable cells of the heart and nervous system as well as in cancer. We consider the therapeutic potential of hERG, not only with regard to the negative impact due to drug induced long QT syndrome, but also its future potential as a treatment in the fight against cancer.
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Affiliation(s)
- John Mitcheson
- University of Leicester, Department of Cell Physiology and Pharmacology, Medical Sciences Building University Road Leicester LE1 9HN UK
| | - Annarosa Arcangeli
- Department of Experimental Pathology and Oncology, University of Florence Viale GB Morgagni, 50 50134 Firenze Italy
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28
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Hausammann GJ, Grütter MG. Chimeric hERG channels containing a tetramerization domain are functional and stable. Biochemistry 2013; 52:9237-45. [PMID: 24325597 DOI: 10.1021/bi401100a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Biochemical and detailed structural information of human ether-a-go-go-related gene (hERG) potassium channels are scarce but are a prerequisite to understand the unwanted interactions of hERG with drugs and the effect of mutations that lead to long QT syndrome. Despite the huge interest in hERG, to our knowledge, procedures that provide a purified, functional, and tetrameric hERG channel are not available. Here, we describe hybrid hERG molecules, termed chimeric hERG channels, in which the N-terminal Per-Arnt-Sim (PAS) domain is deleted and the C-terminal C-linker as well as the cyclic nucleotide binding domain (CNBD) portion is replaced by an artificial tetramerization domain. These chimeric hERG channels can be overexpressed in HEK cells, solubilized in detergent, and purified as tetramers. When expressed in Xenopus laevis oocytes, the chimeric channels exhibit efficient trafficking to the cell surface, whereas a hERG construct lacking the PAS and C-linker/CNBD domains is retained in the cytoplasm. The chimeric hERG channels retain essential hERG functions such as voltage-dependent gating and inhibition by astemizole and the scorpion toxin BeKm-1. The chimeric channels are thus powerful tools for helping to understand the contribution of the cytoplasmic hERG domains to the gating process and are suitable for in vitro biochemical and structural studies.
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Affiliation(s)
- Georg J Hausammann
- From the Department of Biochemistry, University of Zürich , Winterthurerstrasse 190, 8057 Zürich, Switzerland
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29
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Erg potassium currents of neonatal mouse Purkinje cells exhibit fast gating kinetics and are inhibited by mGluR1 activation. J Neurosci 2013; 33:16729-40. [PMID: 24133274 DOI: 10.1523/jneurosci.5523-12.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We investigated the subthreshold properties of an erg (ether-à-go-go-related gene) K(+) current in Purkinje cells of neonatal mice. Action potentials recorded from Purkinje cells in cerebellar slices exhibited a decreased threshold potential and increased frequency of spontaneous and repetitive activity following application of the specific erg channel blocker E-4031. Accommodation was absent before and after drug application. The erg current of these Purkinje cells activated at membrane potentials near -60 mV and exhibited fast gating kinetics. The functional importance of fast gating subthreshold erg channels in Purkinje cells was corroborated by comparing the results of action potential clamp experiments with erg1a, erg1b, erg2, and erg3 currents heterologously expressed in HEK cells. Computer simulations based on a NEURON model of Purkinje cells only reproduced the effects of the native erg current when an erg channel conductance like that of erg3 was included. Experiments with subunit-sensitive toxins (BeKm-1, APETx1) indicated that erg channels in Purkinje cells are presumably mediated by heteromeric erg1/erg3 or modified erg1 channels. Following mGluR1 activation, the native erg current was reduced by ∼70%, brought about by reduction of the maximal erg current and a shift of the activation curve to more positive potentials. The Purkinje cell erg current contributed to the sustained current component of the biphasic mGluR1 response. Activation of mGluR1 by the agonist 3,4-dihydroxyphenylglycol increased Purkinje cell excitability, similar to that induced by E-4031. The results indicated that erg currents can be modulated and may contribute to the mGluR1-induced plasticity changes in Purkinje cells.
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30
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Fiore A, Carraresi L, Morabito A, Polvani S, Fortunato A, Lastraioli E, Femia AP, De Lorenzo E, Caderni G, Arcangeli A. Characterization of hERG1 channel role in mouse colorectal carcinogenesis. Cancer Med 2013; 2:583-94. [PMID: 24403225 PMCID: PMC3892791 DOI: 10.1002/cam4.72] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 01/29/2013] [Accepted: 02/14/2013] [Indexed: 12/13/2022] Open
Abstract
The human ether-à-go-go-related gene (hERG)1 K+ channel is upregulated in human colorectal cancer cells and primary samples. In this study, we examined the role of hERG1 in colorectal carcinogenesis using two mouse models: adenomatous polyposis coli (Apcmin/+) and azoxymethane (AOM)-treated mice. Colonic polyps of Apcmin/+ mice overexpressed mERG1 and their formation was reverted by the hERG1 blocker E4031. AOM was applied to either hERG1-transgenic (TG) mice, which overexpress hERG1 in the mucosa of the large intestine, or wild-type mice. A significant increase of both mucin-depleted foci and polyps in the colon of hERG1-TG mice was detected. Both the intestine of TG mice and colonic polyps of Apcmin/+ showed an upregulation of phospho-Protein Kinase B (pAkt)/vascular endothelial growth factor (VEGF-A) and an increased angiogenesis, which were reverted by treatment with E4031. On the whole, this article assigns a relevant role to hERG1 in the process of in vivo colorectal carcinogenesis.
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Affiliation(s)
- Antonella Fiore
- Department of Experimental and Clinical Medicine, Section of Internal Medicine and Oncology, University of Florence, Florence, Italy; Istituto Toscano Tumori, Florence, Italy
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31
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Abstract
To date, research on the human ether-a-go-go related gene (hERG) has focused on this potassium channel's role in cardiac repolarization and Long QT Syndrome (LQTS). However, growing evidence implicates hERG in a diversity of physiologic and pathological processes. Here we discuss these other functions of hERG, particularly their impact on diseases beyond cardiac arrhythmia.
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32
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Hausammann GJ, Heitkamp T, Matile H, Gsell B, Thoma R, Schmid G, Frasson D, Sievers M, Hennig M, Grütter MG. Generation of an antibody toolbox to characterize hERG. Biochem Biophys Res Commun 2012; 431:70-5. [PMID: 23277102 DOI: 10.1016/j.bbrc.2012.12.089] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 12/20/2012] [Indexed: 11/28/2022]
Abstract
The human ether-a-go-go related gene (hERG) potassium channel plays a major role in the repolarization of the cardiac action potential. Inhibition of the hERG function by mutations or a wide variety of pharmaceutical compounds cause long QT syndrome and lead to potentially lethal arrhythmias. For detailed insights into the structural and biochemical background of hERG function and drug binding, the purification of recombinant protein is essential. Because the hERG channel is a challenging protein to purify, fast and easy techniques to evaluate different expression, solubilization and purification conditions are of primary importance. Here, we describe the generation of a set of 12 monoclonal antibodies against hERG. Beside their suitability in western blot, immunoprecipitation and immunostaining, these antibodies were used to establish a sandwich ELISA for the detection and relative quantification of hERG in different expression systems. Furthermore, a Fab fragment was used in fluorescence size exclusion chromatography to determine the oligomeric state of hERG after solubilization. These new tools can be used for a fast and efficient screening of expression, solubilization and purification conditions.
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Affiliation(s)
- Georg J Hausammann
- Department of Biochemistry, University of Zurich, 8057 Zurich, Switzerland
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33
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Fano S, Çalışkan G, Heinemann U. Differential effects of blockade of ERG channels on gamma oscillations and excitability in rat hippocampal slices. Eur J Neurosci 2012; 36:3628-35. [DOI: 10.1111/ejn.12015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/30/2012] [Accepted: 09/11/2012] [Indexed: 11/28/2022]
Affiliation(s)
- Silvia Fano
- Institute for Neurophysiology; Charité Universitätsmedizin Berlin; Berlin; Germany
| | - Gürsel Çalışkan
- Institute for Neurophysiology; Charité Universitätsmedizin Berlin; Berlin; Germany
| | - Uwe Heinemann
- Institute for Neurophysiology; Charité Universitätsmedizin Berlin; Berlin; Germany
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34
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Vandenberg JI, Perry MD, Perrin MJ, Mann SA, Ke Y, Hill AP. hERG K+ Channels: Structure, Function, and Clinical Significance. Physiol Rev 2012; 92:1393-478. [DOI: 10.1152/physrev.00036.2011] [Citation(s) in RCA: 463] [Impact Index Per Article: 38.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The human ether-a-go-go related gene (hERG) encodes the pore-forming subunit of the rapid component of the delayed rectifier K+ channel, Kv11.1, which are expressed in the heart, various brain regions, smooth muscle cells, endocrine cells, and a wide range of tumor cell lines. However, it is the role that Kv11.1 channels play in the heart that has been best characterized, for two main reasons. First, it is the gene product involved in chromosome 7-associated long QT syndrome (LQTS), an inherited disorder associated with a markedly increased risk of ventricular arrhythmias and sudden cardiac death. Second, blockade of Kv11.1, by a wide range of prescription medications, causes drug-induced QT prolongation with an increase in risk of sudden cardiac arrest. In the first part of this review, the properties of Kv11.1 channels, including biogenesis, trafficking, gating, and pharmacology are discussed, while the second part focuses on the pathophysiology of Kv11.1 channels.
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Affiliation(s)
- Jamie I. Vandenberg
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Matthew D. Perry
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Mark J. Perrin
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Stefan A. Mann
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Ying Ke
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
| | - Adam P. Hill
- Mark Cowley Lidwill Research Programme in Cardiac Electrophysiology, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia; St Vincent's Clinical School, University of New South Wales, New South Wales, Australia; and University of Ottawa Heart Institute, Ottawa, Canada
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35
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Fabbro A, Villari A, Laishram J, Scaini D, Toma FM, Turco A, Prato M, Ballerini L. Spinal cord explants use carbon nanotube interfaces to enhance neurite outgrowth and to fortify synaptic inputs. ACS NANO 2012; 6:2041-55. [PMID: 22339712 DOI: 10.1021/nn203519r] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
New developments in nanotechnology are increasingly designed to modulate relevant interactions between nanomaterials and neurons, with the aim of exploiting the physical properties of synthetic materials to tune desired and specific biological processes. Carbon nanotubes have been applied in several areas of nerve tissue engineering to study cell behavior or to instruct the growth and organization of neural networks. Recent reports show that nanotubes can sustain and promote electrical activity in networks of cultured neurons. However, such results are usually limited to carbon nanotube/neuron hybrids formed on a monolayer of dissociated brain cells. In the present work, we used organotypic spinal slices to model multilayer tissue complexity, and we interfaced such spinal segments to carbon nanotube scaffolds for weeks. By immunofluorescence, scanning and transmission electronic microscopy, and atomic force microscopy, we investigated nerve fiber growth when neuronal processes exit the spinal explant and develop in direct contact to the substrate. By single-cell electrophysiology, we investigated the synaptic activity of visually identified ventral interneurons, within the ventral area of the explant, thus synaptically connected, but located remotely, to the substrate/network interface. Here we show that spinal cord explants interfaced for weeks to purified carbon nanotube scaffolds expand more neuronal fibers, characterized by different mechanical properties and displaying higher growth cones activity. On the other hand, exploring spontaneous and evoked synaptic activity unmasks an increase in synaptic efficacy in neurons located at as far as 5 cell layers from the cell-substrate interactions.
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Affiliation(s)
- Alessandra Fabbro
- Life Science Department, Center for Neuroscience B.R.A.I.N., University of Trieste, via Giorgieri 1, I-34127 Trieste, Italy
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Drexler B, Seeger T, Grasshoff C, Thiermann H, Antkowiak B. Long-term evaluation of organophosphate toxicity and antidotal therapy in co-cultures of spinal cord and muscle tissue. Toxicol Lett 2011; 206:89-93. [PMID: 21530620 DOI: 10.1016/j.toxlet.2011.04.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Accepted: 04/12/2011] [Indexed: 10/18/2022]
Abstract
Victims of nerve agents basically require antidotal treatment. There is need for novel antidotes and for therapeutic procedures that are specifically adapted to these patients. To cope with this challenge, in vitro test systems which are easy to handle and allow for conducting long-term studies would be of great benefit. The present work introduces co-cultures of spinal cord and muscle tissue as ex vivo testing systems meeting these criteria. Cell cultures in which functional neuromuscular synapses formed ex vivo were prepared from embryonic mice. Spontaneous muscle activity was recorded by video microscopy. Muscle contractions involved intact neuromuscular transmission as indicated by the effect of succinylcholine, a muscle relaxant that completely abolished muscle activity. At a concentration of 0.75 μM the nerve agent VX reduced the frequency of spontaneous muscle contractions by about 75%. Subsequent application of obidoxime re-established muscle movements. After 24 h of antidotal treatment, muscle activity approached the level of sham-treated cultures and remained stable over the following week. In summary, co-cultures of spinal cord and muscle tissue are promising tools for evaluating the success of antidotal treatment following organophosphate intoxication over a period of at least seven days.
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Affiliation(s)
- Berthold Drexler
- Department of Anaesthesiology, Experimental Anaesthesiology Section, Eberhard-Karls-University, Schaffhausenstr. 113, 72072 Tuebingen, Germany
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Asher V, Sowter H, Shaw R, Bali A, Khan R. Eag and HERG potassium channels as novel therapeutic targets in cancer. World J Surg Oncol 2010; 8:113. [PMID: 21190577 PMCID: PMC3022597 DOI: 10.1186/1477-7819-8-113] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Accepted: 12/29/2010] [Indexed: 12/03/2022] Open
Abstract
Voltage gated potassium channels have been extensively studied in relation to cancer. In this review, we will focus on the role of two potassium channels, Ether à-go-go (Eag), Human ether à-go-go related gene (HERG), in cancer and their potential therapeutic utility in the treatment of cancer. Eag and HERG are expressed in cancers of various organs and have been implicated in cell cycle progression and proliferation of cancer cells. Inhibition of these channels has been shown to reduce proliferation both in vitro and vivo studies identifying potassium channel modulators as putative inhibitors of tumour progression. Eag channels in view of their restricted expression in normal tissue may emerge as novel tumour biomarkers.
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Affiliation(s)
- Viren Asher
- Department of Obstetrics and Gynaecology, School of Graduate Medicine and Health, Royal Derby Hospital, Uttoxeter road, Derby DE22 3DT, UK.
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38
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Huang MH, Shen AY, Wang TS, Wu HM, Kang YF, Chen CT, Hsu TI, Chen BS, Wu SN. Inhibitory action of methadone and its metabolites on erg-mediated K+ current in GH₃ pituitary tumor cells. Toxicology 2010; 280:1-9. [PMID: 21094671 DOI: 10.1016/j.tox.2010.10.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 10/20/2010] [Accepted: 10/21/2010] [Indexed: 01/05/2023]
Abstract
Methadone (Mtd) is a widely used opioid drug associated with the side effect of hyperprolactinemia. The mechanism of how Mtd induces prolactin secretion remains unclear. The effects of Mtd and its two main metabolites (EDDP: (±)-2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolinium percholarate and EMDP: 2-ethyl-5-methyl-3,3-dipnehyl-1-pyrroline) on ion currents were investigated in GH₃ pituitary tumor cells. Hyperpolarization-elicited K+ currents in GH₃ cells bathed in a high-K(+), Ca(2+)-free solution were studied to evaluate the effects of Mtd and other related compounds on the ether-à-go-go-related-gene (erg) K(+) current (I(K(erg))). Mtd suppressed the amplitude of I(K(erg)) in a concentration-dependent manner with an IC(50) value of 10.4 μM. With the aid of a minimal binding scheme, the inhibitory action of Mtd on I(K(erg)) was estimated with a dissociation constant of 8.2 μM. Mtd tended to increase the rate of I(K(erg)) deactivation in a voltage-dependent fashion. EDDP (10 μM) had no effect on I(K(erg)), while EMDP (10μM) slightly suppressed it. In GH₃ cells incubated with naloxone (30 μM), the Mtd-induced inhibition of I(K(erg)) remained unaltered. Under cell-attached voltage-clamp recordings, Mtd increased the frequency of spontaneous action currents with no change in current amplitude. Similarly, Mtd can suppress I(K(erg)) in differentiated NG108-15 cells; dynorphin A(1-13) did not reverse Mtd-induced inhibition of I(K(erg)). This study shows that Mtd has a depressant effect on I(K(erg)), and suggests its ability to affect membrane excitability and prolactin secretion. The cyclization of Mtd, in which EDDP and EMDP are formed, tends to be critical in removal of the Mtd binding to erg K+ channel.
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Affiliation(s)
- Mei-Han Huang
- College of Medical and Health Sciences, Fooyin University, Ta-Liao, Kaohsiung County, Taiwan
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Arcangeli A, Becchetti A. New Trends in Cancer Therapy: Targeting Ion Channels and Transporters. Pharmaceuticals (Basel) 2010; 3:1202-1224. [PMID: 27713296 PMCID: PMC4034029 DOI: 10.3390/ph3041202] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 03/25/2010] [Accepted: 03/29/2010] [Indexed: 02/07/2023] Open
Abstract
The expression and activity of different channel types mark and regulate specific stages of cancer establishment and progression. Blocking channel activity impairs the growth of some tumors, both in vitro and in vivo, which opens a new field for pharmaceutical research. However, ion channel blockers may produce serious side effects, such as cardiac arrhythmias. For instance, Kv11.1 (hERG1) channels are aberrantly expressed in several human cancers, in which they control different aspects of the neoplastic cell behaviour. hERG1 blockers tend to inhibit cancer growth. However they also retard the cardiac repolarization, thus lengthening the electrocardiographic QT interval, which can lead to life-threatening ventricular arrhythmias. Several possibilities exist to produce less harmful compounds, such as developing specific drugs that bind hERG1 channels in the open state or disassemble the ion channel/integrin complex which appears to be crucial in certain stages of neoplastic progression. The potential approaches to improve the efficacy and safety of ion channel targeting in oncology include: (1) targeting specific conformational channel states; (2) finding ever more specific inhibitors, including peptide toxins, for channel subtypes mainly expressed in well-identified tumors; (3) using specific ligands to convey traceable or cytotoxic compounds; (4) developing channel blocking antibodies; (5) designing new molecular tools to decrease channel expression in selected cancer types. Similar concepts apply to ion transporters such as the Na⁺/K⁺ pump and the Na⁺/H⁺ exchanger. Pharmacological targeting of these transporters is also currently being considered in anti-neoplastic therapy.
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Affiliation(s)
- Annarosa Arcangeli
- Department of Experimental Pathology and Oncology, University of Florence, Italy.
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Italy.
| | - Andrea Becchetti
- Department of Experimental Pathology and Oncology, University of Florence, Italy
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Italy
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Graziadio S, Basu A, Tomasevic L, Zappasodi F, Tecchio F, Eyre JA. Developmental tuning and decay in senescence of oscillations linking the corticospinal system. J Neurosci 2010; 30:3663-74. [PMID: 20220000 PMCID: PMC6632255 DOI: 10.1523/jneurosci.5621-09.2010] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 01/04/2010] [Accepted: 01/11/2010] [Indexed: 11/21/2022] Open
Abstract
There is increasing evidence of the importance of synchronous activity within the corticospinal system for motor control. We compared oscillatory activity in the primary sensorimotor cortex [EEG of sensorimotor cortex (SMC-EEG)] and a motor neuronal pool [surface electromyogram of opponens pollicis (OP-EMG)], and their coherence in children (4-12 years of age), young adults (20-35 years of age), and elderly adults (>55 years of age). The ratio between lower (2-13 Hz) and higher (14-32 Hz) frequencies in both SMC-EEG and OP-EMG decreased with age, correlating inversely with motor performance. There was evidence for larger, more distributed cortical networks in the children and elderly compared with young adults. Corticomuscular coherence (CMC) was present in all age groups and shifted between frontal and parietal cortical areas. In children, CMC was smaller and less stationary in amplitude and frequency than in adults. Young adults had single peaks of CMC clustered near the modal frequency (23 Hz); multiple peaks with a broad spread of frequencies occurred in children and the elderly; the further the frequency of the maximum peak CMC was from 23 Hz, the poorer the performance. CMC amplitude was inversely related to performance in young adults but was not modulated in relation to performance in children and the elderly. We propose that progressive fine-tuning of the frequency coding and stabilization of the dynamic properties within and between corticospinal networks occurs during adolescence, refining the capacity for efficient dynamic communication in adulthood. In old age, blurring of the tuning between networks and breakdown in their integration occurs and is likely to contribute to a decrement in motor control.
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Affiliation(s)
- Sara Graziadio
- Developmental Neuroscience, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 4LP, United Kingdom
| | - Anna Basu
- Developmental Neuroscience, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 4LP, United Kingdom
| | - Leo Tomasevic
- Istituto di Scienze e Tecnologie della Cognizione, National Council for Research, 00186 Rome, Italy
| | - Filippo Zappasodi
- Department of Clinical Sciences and Bioimaging, “G. D'Annunzio” University, 66013 Chieti-Pescara, Italy
- Istituto di Scienze e Tecnologie della Cognizione, National Council for Research, 00186 Rome, Italy
- Associazione Fatebenefratelli per la Ricerca, Center of Medical Statistics and Information Technology, Fatebenefratelli Hospital, 00186 Rome, Italy, and
| | - Franca Tecchio
- Istituto di Scienze e Tecnologie della Cognizione, National Council for Research, 00186 Rome, Italy
- Associazione Fatebenefratelli per la Ricerca, Center of Medical Statistics and Information Technology, Fatebenefratelli Hospital, 00186 Rome, Italy, and
- Casa di Cura San Raffaele Cassino e Istituto di Ricovero e Cura a Carattere Scientifico, San Raffaele Pisana, 00163 Rome, Italy
| | - Janet A. Eyre
- Developmental Neuroscience, Institute of Neuroscience, Newcastle University, Newcastle upon Tyne NE1 4LP, United Kingdom
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Physical and Functional Interaction between Integrins and hERG1 Channels in Cancer Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 674:55-67. [DOI: 10.1007/978-1-4419-6066-5_6] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Chen BS, Lo YC, Peng H, Hsu TI, Wu SN. Effects of ranolazine, a novel anti-anginal drug, on ion currents and membrane potential in pituitary tumor GH(3) cells and NG108-15 neuronal cells. J Pharmacol Sci 2009; 110:295-305. [PMID: 19609066 DOI: 10.1254/jphs.09018fp] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Ranolazine, a piperazine derivative, is currently approved for the treatment of chronic angina. However, its ionic mechanisms in other types of cells remain unclear, although it is thought to be a selective blocker of late Na(+) current. This study was conducted to evaluate the possible effects of ranolazine on Na(+) current (I(Na)), L-type Ca(2+) current (I(Ca,L)), inwardly rectifying K(+) current (I(K(IR))), delayed-rectifier K(+) current (I(K(DR))), and Ca(2+)-activated K(+) current (I(K(Ca))) in pituitary tumor (GH(3)) cells. Ranolazine depressed the transient and late components of I(Na) with different potencies. This drug exerted an inhibitory effect on I(K(IR)) with an IC(50) value of 0.92 microM, while it slightly inhibited I(K(DR)) and I(K(Ca)). It shifted the steady-state activation curve of I(K(IR)) to more positive potentials with no change in the gating charge of the channel. Ranolazine (30 microM) also reduced the activity of large-conductance Ca(2+)-activated K(+) channels in HEK293T cells expressing alpha-hSlo. Under current-clamp conditions, low concentrations (e.g., 1 microM) of ranolazine increased the firing of action potentials, while at high concentrations (>or=10 microM), it diminished the firing discharge. The exposure to ranolazine also suppressed I(Na) and I(K(IR)) effectively in NG108-15 neuronal cells. Our study provides evidence that ranolazine could block multiple ion currents such as I(Na) and I(K(IR)) and suggests that these actions may contribute to some of the functional activities of neurons and endocrine or neuroendocrine cells in vivo.
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Affiliation(s)
- Bing-Shuo Chen
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Taiwan
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Erg K+ currents modulate excitability in mouse mitral/tufted neurons. Pflugers Arch 2009; 459:55-70. [DOI: 10.1007/s00424-009-0709-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2009] [Revised: 06/13/2009] [Accepted: 07/30/2009] [Indexed: 10/20/2022]
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Sibilla S, Fabbro A, Grandolfo M, D'Andrea P, Nistri A, Ballerini L. The patterns of spontaneous Ca2+ signals generated by ventral spinal neurons in vitro show time-dependent refinement. Eur J Neurosci 2009; 29:1543-59. [PMID: 19419420 DOI: 10.1111/j.1460-9568.2009.06708.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Embryonic spinal neurons maintained in organotypic slice culture are known to mimic certain maturation-dependent signalling changes. With such a model we investigated, in embryonic mouse spinal segments, the age-dependent spatio-temporal control of intracellular Ca(2+) signalling generated by neuronal populations in ventral circuits and its relation with electrical activity. We used Ca(2+) imaging to monitor areas located within the ventral spinal horn at 1 and 2 weeks of in vitro growth. Primitive patterns of spontaneous neuronal Ca(2+) transients (detected at 1 week) were typically synchronous. Remarkably, such transients originated from widespread propagating waves that became organized into large-scale rhythmic bursts. These activities were associated with the generation of synaptically mediated inward currents under whole-cell patch-clamp. Such patterns disappeared during longer culture of spinal segments: at 2 weeks in culture, only a subset of ventral neurons displayed spontaneous, asynchronous and repetitive Ca(2+) oscillations dissociated from background synaptic activity. We observed that the emergence of oscillations was a restricted phenomenon arising together with the transformation of ventral network electrophysiological bursting into asynchronous synaptic discharges. This change was accompanied by the appearance of discrete calbindin immunoreactivity against an unchanged background of calretinin-positive cells. It is attractive to assume that periodic oscillations of Ca(2+) confer a summative ability to these cells to shape the plasticity of local circuits through different changes (phasic or tonic) in intracellular Ca(2+).
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Affiliation(s)
- Sara Sibilla
- Physiology and Pathology Department, Centre for Neuroscience BRAIN, University of Trieste, via Fleming 22, 34127 Trieste, Italy
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Sibilla S, Ballerini L. GABAergic and glycinergic interneuron expression during spinal cord development: dynamic interplay between inhibition and excitation in the control of ventral network outputs. Prog Neurobiol 2009; 89:46-60. [PMID: 19539686 DOI: 10.1016/j.pneurobio.2009.06.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Revised: 04/10/2009] [Accepted: 06/09/2009] [Indexed: 11/28/2022]
Abstract
A key objective of neuroscience research is to understand the processes leading to mature neural circuitries in the central nervous system (CNS) that enable the control of different behaviours. During development, network-constitutive neurons undergo dramatic rearrangements, involving their intrinsic properties, such as the blend of ion channels governing their firing activity, and their synaptic interactions. The spinal cord is no exception to this rule; in fact, in the ventral horn the maturation of motor networks into functional circuits is a complex process where several mechanisms cooperate to achieve the development of motor control. Elucidating such a process is crucial in identifying neurons more vulnerable to degenerative or traumatic diseases or in developing new strategies aimed at rebuilding damaged tissue. The focus of this review is on recent advances in understanding the spatio-temporal expression of the glycinergic/GABAergic system and on the contribution of this system to early network function and to motor pattern transformation along with spinal maturation. During antenatal development, the operation of mammalian spinal networks strongly depends on the activity of glycinergic/GABAergic neurons, whose action is often excitatory until shortly before birth when locomotor networks acquire the ability to generate alternating motor commands between flexor and extensor motor neurons. At this late stage of prenatal development, GABA-mediated excitation is replaced by synaptic inhibition mediated by glycine and/or GABA. At this stage of spinal maturation, the large majority of GABAergic neurons are located in the dorsal horn. We propose that elucidating the role of inhibitory systems in development will improve our knowledge on the processes regulating spinal cord maturation.
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Affiliation(s)
- Sara Sibilla
- Life Science Department, Center for Neuroscience B.R.A.I.N., University of Trieste, via Fleming 22, 34127 Trieste, Italy
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Homeostatic control of sensory output in basal vomeronasal neurons: activity-dependent expression of ether-à-go-go-related gene potassium channels. J Neurosci 2009; 29:206-21. [PMID: 19129398 DOI: 10.1523/jneurosci.3656-08.2009] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Conspecific chemosensory communication controls a broad range of social and sexual behaviors. In most mammals, social chemosignals are predominantly detected by sensory neurons of a specialized olfactory subsystem, the vomeronasal organ (VNO). The behavioral relevance of social chemosignaling puts high demands on the accuracy and dynamic range of the underlying transduction mechanisms. However, the physiological concepts implemented to ensure faithful transmission of social information remain widely unknown. Here, we show that sensory neurons in the basal layer of the mouse VNO dynamically control their input-output relationship by activity-dependent regulation of K(+) channel gene expression. Using large-scale expression profiling, immunochemistry, and electrophysiology, we provide molecular and functional evidence for a role of ether-à-go-go-related gene (ERG) K(+) channels as key determinants of cellular excitability. Our findings indicate that an increase in ERG channel expression extends the dynamic range of the stimulus-response function in basal vomeronasal sensory neurons. This novel mechanism of homeostatic plasticity in the periphery of the accessory olfactory system is ideally suited to adjust VNO neurons to a target output range in a layer-specific and use-dependent manner.
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Pessia M, Servettini I, Panichi R, Guasti L, Grassi S, Arcangeli A, Wanke E, Pettorossi VE. ERG voltage-gated K+ channels regulate excitability and discharge dynamics of the medial vestibular nucleus neurones. J Physiol 2008; 586:4877-90. [PMID: 18718985 PMCID: PMC2614050 DOI: 10.1113/jphysiol.2008.155762] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 08/14/2008] [Indexed: 11/08/2022] Open
Abstract
The discharge properties of the medial vestibular nucleus neurones (MVNn) critically depend on the activity of several ion channel types. In this study we show, immunohistochemically, that the voltage-gated K(+) channels ERG1A, ERG1B, ERG2 and ERG3 are highly expressed within the vestibular nuclei of P10 and P60 mice. The role played by these channels in the spike-generating mechanisms of the MVNn and in temporal information processing was investigated electrophysiologically from mouse brain slices, in vitro, by analysing the spontaneous discharge and the response to square-, ramp- and sinusoid-like intracellular DC current injections in extracellular and whole-cell patch-clamp studies. We show that more than half of the recorded MVNn were responsive to ERG channel block (WAY-123,398, E4031), displaying an increase in spontaneous activity and discharge irregularity. The response to step and ramp current injection was also modified by ERG block showing a reduction of first spike latency, enhancement of discharge rate and reduction of the slow spike-frequency adaptation process. ERG channels influence the interspike slope without affecting the spike shape. Moreover, in response to sinusoid-like current, ERG channel block caused frequency-dependent gain enhancement and phase-lead shift. Taken together, the data demonstrate that ERG channels control the excitability of MVNn, their discharge regularity and probably their resonance properties.
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Affiliation(s)
- Mauro Pessia
- Department of Internal Medicine, Section of Human Physiology, University of Perugia, Perugia, Italy.
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Johnston J, Griffin SJ, Baker C, Skrzypiec A, Chernova T, Forsythe ID. Initial segment Kv2.2 channels mediate a slow delayed rectifier and maintain high frequency action potential firing in medial nucleus of the trapezoid body neurons. J Physiol 2008; 586:3493-509. [PMID: 18511484 DOI: 10.1113/jphysiol.2008.153734] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The medial nucleus of the trapezoid body (MNTB) is specialized for high frequency firing by expression of Kv3 channels, which minimize action potential (AP) duration, and Kv1 channels, which suppress multiple AP firing, during each calyceal giant EPSC. However, the outward K(+) current in MNTB neurons is dominated by another unidentified delayed rectifier. It has slow kinetics and a peak conductance of approximately 37 nS; it is half-activated at -9.2 +/- 2.1 mV and half-inactivated at -35.9 +/- 1.5 mV. It is blocked by several non-specific potassium channel antagonists including quinine (100 microm) and high concentrations of extracellular tetraethylammonium (TEA; IC(50) = 11.8 mM), but no specific antagonists were found. These characteristics are similar to recombinant Kv2-mediated currents. Quantitative RT-PCR showed that Kv2.2 mRNA was much more prevalent than Kv2.1 in the MNTB. A Kv2.2 antibody showed specific staining and Western blots confirmed that it recognized a protein approximately 110 kDa which was absent in brainstem tissue from a Kv2.2 knockout mouse. Confocal imaging showed that Kv2.2 was highly expressed in axon initial segments of MNTB neurons. In the absence of a specific antagonist, Hodgkin-Huxley modelling of voltage-gated conductances showed that Kv2.2 has a minor role during single APs (due to its slow activation) but assists recovery of voltage-gated sodium channels (Nav) from inactivation by hyperpolarizing interspike potentials during repetitive AP firing. Current-clamp recordings during high frequency firing and characterization of Nav inactivation confirmed this hypothesis. We conclude that Kv2.2-containing channels have a distinctive initial segment location and crucial function in maintaining AP amplitude by regulating the interspike potential during high frequency firing.
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Affiliation(s)
- Jamie Johnston
- MRC Toxicology Unit, University of Leicester, Leicester LE1 9HN, UK
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Czarnecki A, Magloire V, Streit J. Local oscillations of spiking activity in organotypic spinal cord slice cultures. Eur J Neurosci 2008; 27:2076-88. [DOI: 10.1111/j.1460-9568.2008.06171.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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