1
|
Feher A, Pócsi M, Papp F, Szanto TG, Csoti A, Fejes Z, Nagy B, Nemes B, Varga Z. Functional Voltage-Gated Sodium Channels Are Present in the Human B Cell Membrane. Cells 2022; 11:1225. [PMID: 35406789 PMCID: PMC8998058 DOI: 10.3390/cells11071225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 03/31/2022] [Accepted: 04/03/2022] [Indexed: 02/04/2023] Open
Abstract
B cells express various ion channels, but the presence of voltage-gated sodium (NaV) channels has not been confirmed in the plasma membrane yet. In this study, we have identified several NaV channels, which are expressed in the human B cell membrane, by electrophysiological and molecular biology methods. The sensitivity of the detected sodium current to tetrodotoxin was between the values published for TTX-sensitive and TTX-insensitive channels, which suggests the co-existence of multiple NaV1 subtypes in the B cell membrane. This was confirmed by RT-qPCR results, which showed high expression of TTX-sensitive channels along with the lower expression of TTX-insensitive NaV1 channels. The biophysical characteristics of the currents also supported the expression of multiple NaV channels. In addition, we investigated the potential functional role of NaV channels by membrane potential measurements. Removal of Na+ from the extracellular solution caused a reversible hyperpolarization, supporting the role of NaV channels in shaping and maintaining the resting membrane potential. As this study was mainly limited to electrophysiological properties, we cannot exclude the possible non-canonical functions of these channels. This work concludes that the presence of voltage-gated sodium channels in the plasma membrane of human B cells should be recognized and accounted for in the future.
Collapse
Affiliation(s)
- Adam Feher
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (A.F.); (F.P.); (T.G.S.); (A.C.)
| | - Marianna Pócsi
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (M.P.); (Z.F.); (B.N.J.)
| | - Ferenc Papp
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (A.F.); (F.P.); (T.G.S.); (A.C.)
| | - Tibor G. Szanto
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (A.F.); (F.P.); (T.G.S.); (A.C.)
| | - Agota Csoti
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (A.F.); (F.P.); (T.G.S.); (A.C.)
| | - Zsolt Fejes
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (M.P.); (Z.F.); (B.N.J.)
| | - Béla Nagy
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (M.P.); (Z.F.); (B.N.J.)
| | - Balázs Nemes
- Department of Organ Transplantation, Faculty of Medicine, Institute of Surgery, University of Debrecen, H-4032 Debrecen, Hungary;
| | - Zoltan Varga
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, H-4032 Debrecen, Hungary; (A.F.); (F.P.); (T.G.S.); (A.C.)
| |
Collapse
|
2
|
Boscia F, Elkjaer ML, Illes Z, Kukley M. Altered Expression of Ion Channels in White Matter Lesions of Progressive Multiple Sclerosis: What Do We Know About Their Function? Front Cell Neurosci 2021; 15:685703. [PMID: 34276310 PMCID: PMC8282214 DOI: 10.3389/fncel.2021.685703] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2021] [Accepted: 05/23/2021] [Indexed: 12/19/2022] Open
Abstract
Despite significant advances in our understanding of the pathophysiology of multiple sclerosis (MS), knowledge about contribution of individual ion channels to axonal impairment and remyelination failure in progressive MS remains incomplete. Ion channel families play a fundamental role in maintaining white matter (WM) integrity and in regulating WM activities in axons, interstitial neurons, glia, and vascular cells. Recently, transcriptomic studies have considerably increased insight into the gene expression changes that occur in diverse WM lesions and the gene expression fingerprint of specific WM cells associated with secondary progressive MS. Here, we review the ion channel genes encoding K+, Ca2+, Na+, and Cl- channels; ryanodine receptors; TRP channels; and others that are significantly and uniquely dysregulated in active, chronic active, inactive, remyelinating WM lesions, and normal-appearing WM of secondary progressive MS brain, based on recently published bulk and single-nuclei RNA-sequencing datasets. We discuss the current state of knowledge about the corresponding ion channels and their implication in the MS brain or in experimental models of MS. This comprehensive review suggests that the intense upregulation of voltage-gated Na+ channel genes in WM lesions with ongoing tissue damage may reflect the imbalance of Na+ homeostasis that is observed in progressive MS brain, while the upregulation of a large number of voltage-gated K+ channel genes may be linked to a protective response to limit neuronal excitability. In addition, the altered chloride homeostasis, revealed by the significant downregulation of voltage-gated Cl- channels in MS lesions, may contribute to an altered inhibitory neurotransmission and increased excitability.
Collapse
Affiliation(s)
- Francesca Boscia
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, University of Naples "Federico II", Naples, Italy
| | - Maria Louise Elkjaer
- Neurology Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Zsolt Illes
- Neurology Research Unit, Department of Clinical Research, University of Southern Denmark, Odense, Denmark.,Department of Neurobiology Research, Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark.,Department of Neurology, Odense University Hospital, Odense, Denmark
| | - Maria Kukley
- Achucarro Basque Center for Neuroscience, Leioa, Spain.,Ikerbasque Basque Foundation for Science, Bilbao, Spain
| |
Collapse
|
3
|
McNeill J, Rudyk C, Hildebrand ME, Salmaso N. Ion Channels and Electrophysiological Properties of Astrocytes: Implications for Emergent Stimulation Technologies. Front Cell Neurosci 2021; 15:644126. [PMID: 34093129 PMCID: PMC8173131 DOI: 10.3389/fncel.2021.644126] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 04/26/2021] [Indexed: 12/12/2022] Open
Abstract
Astrocytes comprise a heterogeneous cell population characterized by distinct morphologies, protein expression and function. Unlike neurons, astrocytes do not generate action potentials, however, they are electrically dynamic cells with extensive electrophysiological heterogeneity and diversity. Astrocytes are hyperpolarized cells with low membrane resistance. They are heavily involved in the modulation of K+ and express an array of different voltage-dependent and voltage-independent channels to help with this ion regulation. In addition to these K+ channels, astrocytes also express several different types of Na+ channels; intracellular Na+ signaling in astrocytes has been linked to some of their functional properties. The physiological hallmark of astrocytes is their extensive intracellular Ca2+ signaling cascades, which vary at the regional, subregional, and cellular levels. In this review article, we highlight the physiological properties of astrocytes and the implications for their function and influence of network and synaptic activity. Furthermore, we discuss the implications of these differences in the context of optogenetic and DREADD experiments and consider whether these tools represent physiologically relevant techniques for the interrogation of astrocyte function.
Collapse
Affiliation(s)
- Jessica McNeill
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | | | | | - Natalina Salmaso
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| |
Collapse
|
4
|
Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| |
Collapse
|
5
|
Smith RS, Kenny CJ, Ganesh V, Jang A, Borges-Monroy R, Partlow JN, Hill RS, Shin T, Chen AY, Doan RN, Anttonen AK, Ignatius J, Medne L, Bönnemann CG, Hecht JL, Salonen O, Barkovich AJ, Poduri A, Wilke M, de Wit MCY, Mancini GMS, Sztriha L, Im K, Amrom D, Andermann E, Paetau R, Lehesjoki AE, Walsh CA, Lehtinen MK. Sodium Channel SCN3A (Na V1.3) Regulation of Human Cerebral Cortical Folding and Oral Motor Development. Neuron 2018; 99:905-913.e7. [PMID: 30146301 DOI: 10.1016/j.neuron.2018.07.052] [Citation(s) in RCA: 100] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 06/05/2018] [Accepted: 07/30/2018] [Indexed: 12/29/2022]
Abstract
Channelopathies are disorders caused by abnormal ion channel function in differentiated excitable tissues. We discovered a unique neurodevelopmental channelopathy resulting from pathogenic variants in SCN3A, a gene encoding the voltage-gated sodium channel NaV1.3. Pathogenic NaV1.3 channels showed altered biophysical properties including increased persistent current. Remarkably, affected individuals showed disrupted folding (polymicrogyria) of the perisylvian cortex of the brain but did not typically exhibit epilepsy; they presented with prominent speech and oral motor dysfunction, implicating SCN3A in prenatal development of human cortical language areas. The development of this disorder parallels SCN3A expression, which we observed to be highest early in fetal cortical development in progenitor cells of the outer subventricular zone and cortical plate neurons and decreased postnatally, when SCN1A (NaV1.1) expression increased. Disrupted cerebral cortical folding and neuronal migration were recapitulated in ferrets expressing the mutant channel, underscoring the unexpected role of SCN3A in progenitor cells and migrating neurons.
Collapse
Affiliation(s)
- Richard S Smith
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Connor J Kenny
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Vijay Ganesh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ahram Jang
- Department of Pathology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Rebeca Borges-Monroy
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jennifer N Partlow
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - R Sean Hill
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Taehwan Shin
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Allen Y Chen
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ryan N Doan
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Anna-Kaisa Anttonen
- The Folkhälsan Institute of Genetics, 00290 Helsinki, Finland; Medical and Clinical Genetics, Neuroscience Center and Research Programs Unit, Molecular Neurology, 00014, University of Helsinki, Helsinki, Finland
| | - Jaakko Ignatius
- Department of Clinical Genetics, Turku University Hospital, Turku, 20521, Finland
| | - Livija Medne
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Carsten G Bönnemann
- Division of Human Genetics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Jonathan L Hecht
- Department of Pathology, Beth Israel Deaconess Medical Center, Boston, MA 02115, USA
| | - Oili Salonen
- Medical Imaging Center, Radiology, University of Helsinki and Helsinki University Hospital, 00029 HUS, Helsinki, Finland
| | - A James Barkovich
- Benioff Children's Hospital, Departments of Radiology, Pediatrics, Neurology, and Neurological Surgery, University of California San Francisco, San Francisco, CA 94117, USA
| | - Annapurna Poduri
- Department of Neurology, Boston Children's Hospital and Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Martina Wilke
- Department of Clinical Genetics, Erasmus MC Rotterdam 3015CN, Netherlands
| | - Marie Claire Y de Wit
- Neurogenetics Joint Clinic in Sophia Children's Hospital, Erasmus MC Rotterdam 3015CN, Netherlands
| | - Grazia M S Mancini
- Department of Clinical Genetics, Erasmus MC Rotterdam 3015CN, Netherlands
| | - Laszlo Sztriha
- Department of Pediatrics, College of Medicine and Health Sciences, United Arab Emirates University, Al-Ain, United Arab Emirates
| | - Kiho Im
- Division of Newborn Medicine, Boston Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Dina Amrom
- Neurogenetics Unit and Epilepsy Research Group, Montreal Neurological Institute and Hospital; and the Departments of Neurology & Neurosurgery and Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada
| | - Eva Andermann
- Neurogenetics Unit and Epilepsy Research Group, Montreal Neurological Institute and Hospital; and the Departments of Neurology & Neurosurgery and Human Genetics, McGill University, Montreal, QC H3A 2B4, Canada
| | - Ritva Paetau
- Children's Hospital, University of Helsinki and Helsinki University Hospital, 00029 HUS, Helsinki, Finland
| | - Anna-Elina Lehesjoki
- The Folkhälsan Institute of Genetics, 00290 Helsinki, Finland; Medical and Clinical Genetics, Neuroscience Center and Research Programs Unit, Molecular Neurology, 00014, University of Helsinki, Helsinki, Finland
| | - Christopher A Walsh
- Division of Genetics and Genomics, Manton Center for Orphan Disease Research, and Howard Hughes Medical Institute, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
| | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, MA 02115, USA.
| |
Collapse
|
6
|
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| |
Collapse
|
7
|
Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 945] [Impact Index Per Article: 157.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| |
Collapse
|
8
|
Catterall WA. Forty Years of Sodium Channels: Structure, Function, Pharmacology, and Epilepsy. Neurochem Res 2017; 42:2495-2504. [PMID: 28589518 PMCID: PMC5693772 DOI: 10.1007/s11064-017-2314-9] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/19/2017] [Accepted: 05/26/2017] [Indexed: 11/24/2022]
Abstract
Voltage-gated sodium channels initiate action potentials in brain neurons. In the 1970s, much was known about the function of sodium channels from measurements of ionic currents using the voltage clamp method, but there was no information about the sodium channel molecules themselves. As a postdoctoral fellow and staff scientist at the National Institutes of Health, I developed neurotoxins as molecular probes of sodium channels in cultured neuroblastoma cells. During those years, Bruce Ransom and I crossed paths as members of the laboratories of Marshall Nirenberg and Philip Nelson and shared insights about sodium channels in neuroblastoma cells from my work and electrical excitability and synaptic transmission in cultured spinal cord neurons from Bruce's pioneering electrophysiological studies. When I established my laboratory at the University of Washington in 1977, my colleagues and I used those neurotoxins to identify the protein subunits of sodium channels, purify them, and reconstitute their ion conductance activity in pure form. Subsequent studies identified the molecular basis for the main functions of sodium channels-voltage-dependent activation, rapid and selective ion conductance, and fast inactivation. Bruce Ransom and I re-connected in the 1990s, as ski buddies at the Winter Conference on Brain Research and as faculty colleagues at the University of Washington when Bruce became our founding Chair of Neurology and provided visionary leadership of that department. In the past decade my work on sodium channels has evolved into structural biology. Molecular modeling and X-ray crystallographic studies have given new views of sodium channel function at atomic resolution. Sodium channels are also the molecular targets for genetic diseases, including Dravet Syndrome, an intractable pediatric epilepsy disorder with major co-morbidities of cognitive deficit, autistic-like behaviors, and premature death that is caused by loss-of-function mutations in the brain sodium channel NaV1.1. Our work on a mouse genetic model of this disease has shown that its multi-faceted pathophysiology and co-morbidities derive from selective loss of electrical excitability and action potential firing in GABAergic inhibitory neurons, which disinhibits neural circuits throughout the brain and leads directly to the epilepsy, premature death and complex co-morbidities of this disease. It has been rewarding for me to use our developing knowledge of sodium channels to help understand the pathophysiology and to suggest potential therapeutic approaches for this devastating childhood disease.
Collapse
Affiliation(s)
- William A Catterall
- Department of Pharmacology, University of Washington, Seattle, WA, 98195-7280, USA.
| |
Collapse
|
9
|
Abstract
In a career that has spanned 45 years and shows no signs of slowing down, Dr Bruce Ransom has devoted considerable time and energy to studying regulation of interstitial K+. When Bruce commenced his studies in 1969 virtually nothing was known of the functions of glial cells, but Bruce’s research contributed to the physiological assignation of function to mammalian astrocytes, namely interstitial K+ buffering. The experiments that I describe in this review concern the response of the membrane potential (Em) of in vivo cat cortical astrocytes to changes in [K+]o, an experimental manoeuvre that was achieved in two different ways. The first involved recording the Em of an astrocyte while the initial aCSF was switched to one with different K+, whereas in the second series of experiments the cortex was stimulated and the response of the astrocyte Em to the K+ released from neighbouring neurons was recorded. The astrocytes responded in a qualitatively predictable manner, but quantitatively the changes were not as predicted by the Nernst equation. Elevations in interstitial K+ are not sustained and K+ returns to baseline rapidly due to the buffering capacity of astrocytes, a phenomenon studied by Bruce, and his son Chris, published 27 years after Bruce’s initial publications. Thus, a lifetime spent investigating K+ buffering has seen enormous advances in glial research, from the time cells were identified as ‘presumed’ glial cells or ‘silent cells’, to the present day, where glial cells are recognised as contributing to every important physiological brain function.
Collapse
Affiliation(s)
- Angus M Brown
- School of Life Sciences, University of Nottingham, Nottingham, NG7 2UH, UK. .,Department of Neurology, University of Washington, Seattle, WA, 98195, USA.
| |
Collapse
|
10
|
Pappalardo LW, Black JA, Waxman SG. Sodium channels in astroglia and microglia. Glia 2016; 64:1628-45. [PMID: 26919466 DOI: 10.1002/glia.22967] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 12/27/2015] [Accepted: 01/04/2016] [Indexed: 12/19/2022]
Abstract
Voltage-gated sodium channels are required for electrogenesis in excitable cells. Their activation, triggered by membrane depolarization, generates transient sodium currents that initiate action potentials in neurons, cardiac, and skeletal muscle cells. Cells that have not traditionally been considered to be excitable (nonexcitable cells), including glial cells, also express sodium channels in physiological conditions as well as in pathological conditions. These channels contribute to multiple functional roles that are seemingly unrelated to the generation of action potentials. Here, we discuss the dynamics of sodium channel expression in astrocytes and microglia, and review evidence for noncanonical roles in effector functions of these cells including phagocytosis, migration, proliferation, ionic homeostasis, and secretion of chemokines/cytokines. We also examine possible mechanisms by which sodium channels contribute to the activity of glial cells, with an eye toward therapeutic implications for central nervous system disease. GLIA 2016;64:1628-1645.
Collapse
Affiliation(s)
- Laura W Pappalardo
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| | - Joel A Black
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| | - Stephen G Waxman
- Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, CT.,Rehabilitation Research Center, VA Connecticut Healthcare System, West Haven, CT
| |
Collapse
|
11
|
Abstract
Local anesthetics (LA) are broadly used in all disciplines and it could be considered that relatively little is reflected on the mechanisms of action of this old substance group. However, several molecular mechanisms of LAs mediating wanted and unwanted effects remain to be explored. Furthermore, the number of indications for application of LAs seems to be expanding. The local anesthetic effect of LAs is primarily mediated by a potent inhibition of voltage-gated sodium channels. However, this effect is due to much more than the interaction of LAs with one single molecule. Most recent studies indicated that the development of selective local anesthetics might be possible and LAs also interact with several other membrane molecules. Although the relevance of these effects is still unclear, they might play a role in systemic analgesia, tissue protection and anti-inflammatory effects of LA. The therapeutic index of systemically applied LA is very narrow. Systemic application is formally not permitted because the impending systemic toxicity is still a life-threatening complication. Although the cardiac and central nervous toxicity at least partly result from an unselective block of neuronal and cardiac sodium channels, preclinical studies suggest the involvement of several mechanisms. A local LA toxicity is less clinically impressive; however, all LAs induce a significant tissue toxicity for which the underlying mechanisms have been partly identified. This review reports on recent findings on mechanisms and on the clinical relevance of some LA-induced effects which are of relevance for anesthesiological activities.
Collapse
Affiliation(s)
- J Ahrens
- Klinik für Anästhesiologie und Intensivmedizin, Medizinische Hochschule Hannover, Carl-Neuberg-Str. 1, 30625, Hannover, Deutschland
| | | |
Collapse
|
12
|
Black J, Waxman S. Noncanonical Roles of Voltage-Gated Sodium Channels. Neuron 2013; 80:280-91. [DOI: 10.1016/j.neuron.2013.09.012] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/11/2013] [Indexed: 12/19/2022]
|
13
|
Lisak RP, Benjamins JA, Bealmear B, Nedelkoska L, Studzinski D, Retland E, Yao B, Land S. Differential effects of Th1, monocyte/macrophage and Th2 cytokine mixtures on early gene expression for molecules associated with metabolism, signaling and regulation in central nervous system mixed glial cell cultures. J Neuroinflammation 2009; 6:4. [PMID: 19159481 PMCID: PMC2639549 DOI: 10.1186/1742-2094-6-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Accepted: 01/21/2009] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Cytokines secreted by immune cells and activated glia play central roles in both the pathogenesis of and protection from damage to the central nervous system (CNS) in multiple sclerosis (MS). METHODS We have used gene array analysis to identify the initial direct effects of cytokines on CNS glia by comparing changes in early gene expression in CNS glial cultures treated for 6 hours with cytokines typical of those secreted by Th1 and Th2 lymphocytes and monocyte/macrophages (M/M). RESULTS In two previous papers, we summarized effects of these cytokines on immune-related molecules, and on neural and glial related proteins, including neurotrophins, growth factors and structural proteins. In this paper, we present the effects of the cytokines on molecules involved in metabolism, signaling and regulatory mechanisms in CNS glia. Many of the changes in gene expression were similar to those seen in ischemic preconditioning and in early inflammatory lesions in experimental autoimmune encephalomyelitis (EAE), related to ion homeostasis, mitochondrial function, neurotransmission, vitamin D metabolism and a variety of transcription factors and signaling pathways. Among the most prominent changes, all three cytokine mixtures markedly downregulated the dopamine D3 receptor, while Th1 and Th2 cytokines downregulated neuropeptide Y receptor 5. An unexpected finding was the large number of changes related to lipid metabolism, including several suggesting a switch from diacylglycerol to phosphatidyl inositol mediated signaling pathways. Using QRT-PCR we validated the results for regulation of genes for iNOS, arginase and P glycoprotein/multi-drug resistance protein 1 (MDR1) seen at 6 hours with microarray. CONCLUSION Each of the three cytokine mixtures differentially regulated gene expression related to metabolism and signaling that may play roles in the pathogenesis of MS, most notably with regard to mitochondrial function and neurotransmitter signaling in glia.
Collapse
Affiliation(s)
- Robert P Lisak
- Department of Neurology, 8D University Health Center, Wayne State University School of Medicine, 4201 St Antoine, Detroit, MI, 48210, USA.
| | | | | | | | | | | | | | | |
Collapse
|
14
|
Marin P, Fagni L, Torrens Y, Alcaraz G, Couraud F, Bockaert J, Glowinski J, Prémont J. AMPA receptor activation induces association of G-beta protein with the alpha subunit of the sodium channel in neurons. Eur J Neurosci 2001; 14:1953-60. [PMID: 11860490 DOI: 10.1046/j.0953-816x.2001.01827.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Glutamatergic transmission is mediated by ionotropic receptors that directly gate cationic channels and metabotropic receptors that are coupled to second messenger generating systems and to ionic channels via heterotrimeric guanine-nucleotide binding- (G) proteins. This distinction cannot be made for the ionotropic receptor subclass activated by alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA), which has been shown to be physically associated with the alpha-subunit of Gi1 protein and activates this G-protein. Here, we report that, in addition to a Ca2+ influx, AMPA induces the mobilization of Ca2+ from the mitochondrial pool by reversing the mitochondrial Na+/Ca2+ exchanger in mouse neurons in primary culture. Both processes required the activation of tetrodotoxin-sensitive Na+ channels. AMPA receptor activation modified the gating properties of the Na+ channel, independently of the AMPA current, suggesting a G-protein-mediated process. Indeed, co-immunoprecipitation experiments indicated that AMPA receptor activation induced the association of Gbeta with the alpha-subunit of the Na+ channel. These results suggest that, in addition to its ionic channel function, the AMPA receptor is coupled to Na+ channels through G-proteins and that this novel metabotropic function is involved in the control of neuronal excitability.
Collapse
Affiliation(s)
- P Marin
- INSERM U114, Collège de France, 11, Place Marcelin Berthelot, 75231 Paris Cedex 05, France
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Perillán PR, Li X, Potts EA, Chen M, Bredt DS, Simard JM. Inward rectifier K(+) channel Kir2.3 (IRK3) in reactive astrocytes from adult rat brain. Glia 2000; 31:181-92. [PMID: 10878604 DOI: 10.1002/1098-1136(200008)31:2<181::aid-glia90>3.0.co;2-8] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Astrocytic inward rectifying K(+) channels that participate in K(+) spatial buffering in the central nervous system have been extensively investigated, but specific gene products have not been fully identified. We studied primary cultured reactive astrocytes of stellate and polygonal morphology from adult rat brains, as well as stellate astrocytes from neonatal rat brains. Single-channel recordings of cell-attached patches revealed that polygonal reactive astrocytes expressed only one hyperpolarization-activated single-channel conductance of 11-15 pS whose open probability was independent of voltage, whereas stellate reactive and stellate neonatal astrocytes exhibited two conductances, 11-15 pS and 24-27 pS. All three subtypes of astrocytes exhibited a hyperpolarization-activated macroscopic inward K(+) current that was strongly rectifying and was abrogated by 1 mM intracellular Mg(2+) introduced during conventional but not perforated patch whole-cell recording. This Mg(2+)-sensitive current comprised the total inward rectifier current in polygonal reactive astrocytes, but only a fraction of the inward rectifier current in stellate reactive and stellate neonatal astrocytes. Because a strongly rectifying, inward rectifier K(+) channel with a single-channel conductance of 11-15 pS that is voltage independent is consistent with features of Kir2.3 (IRK3), we performed immunofluorescence experiments with anti-Kir2.3 and anti-glial fibrillary acidic protein antibodies. Both antibodies co-localized to all three subtypes of astrocytes in primary culture and to reactive astrocytes in situ within brain and gelatin sponge implants. Our data indicate that astrocytes of both polygonal and stellate morphology, from both adult and neonatal rat brain, express Kir2.3 both in vivo and in vitro. Constitutive expression of Kir2.3 regardless of cell morphology or age of origin of the source tissue suggests an important functional role for this channel in astrocytes.
Collapse
Affiliation(s)
- P R Perillán
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA
| | | | | | | | | | | |
Collapse
|
16
|
Abstract
Functional and molecular analysis of glial voltage- and ligand-gated ion channels underwent tremendous boost over the last 15 years. The traditional image of the glial cell as a passive, structural element of the nervous system was transformed into the concept of a plastic cell, capable of expressing a large variety of ion channels and neurotransmitter receptors. These molecules might enable glial cells to sense neuronal activity and to integrate it within glial networks, e.g., by means of spreading calcium waves. In this review we shall give a comprehensive summary of the main functional properties of ion channels and ionotropic receptors expressed by macroglial cells, i.e., by astrocytes, oligodendrocytes and Schwann cells. In particular we will discuss in detail glial sodium, potassium and anion channels, as well as glutamate, GABA and ATP activated ionotropic receptors. A majority of available data was obtained from primary cell culture, these results have been compared with corresponding studies that used acute tissue slices or freshly isolated cells. In view of these data, an active glial participation in information processing seems increasingly likely and a physiological role for some of the glial channels and receptors is gradually emerging.
Collapse
Affiliation(s)
- A Verkhratsky
- School of Biological Sciences, The University of Manchester, Oxford Road, Manchester, UK.
| | | |
Collapse
|
17
|
Abstract
The expression of the alpha-subunit of voltage-gated sodium channel 6 (NaCh6) was examined in cultures of astrocytes from E18 rat spinal cord by using an antibody specific for NaCh6. Stellate cells with processes and flat, pancake-like astrocytes are the two morphological types predominantly present in these cultures. The antibody to NaCh6 labeled clusters at the cell body and along the length of the processes in stellate, process-bearing cells. Weak staining was observed in the flat, pancake-like astrocytes. Together with previous studies (Black et al., Mol Brain Res 23:235-245, 1994, Glia 14:133-144, 1995) that show that stellate cells express NaChs II and III (but not NaCh I) and flat cells express NaCh II, these results support the conclusions that there are different patterns of sodium channel expression between flat and stellate astrocytes and that multiple channel isoforms are expressed within the same cell. This study also suggests that NaCh6 may contribute to the electrical properties found in stellate astrocytes.
Collapse
Affiliation(s)
- K A Reese
- Neuroscience Program and Department of Cellular and Structural Biology, University of Colorado Health Sciences Center, Denver, USA
| | | |
Collapse
|
18
|
|
19
|
Rose CR, Ransom BR, Waxman SG. Pharmacological characterization of Na+ influx via voltage-gated Na+ channels in spinal cord astrocytes. J Neurophysiol 1997; 78:3249-58. [PMID: 9405543 DOI: 10.1152/jn.1997.78.6.3249] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Spinal cord astrocytes display a high density of voltage-gated Na+ channels. To study the contribution of Na+ influx via these channels to Na+ homeostasis in cultured spinal cord astrocytes, we measured intracellular Na+ concentration ([Na+]i) with the fluorescent dye sodium-binding benzofuran isophthalate. Stellate and nonstellate astrocytes, which display Na+ currents with different properties, were differentiated. Baseline [Na+]i was 8.5 mM in these cells and was not altered by 100 microM tetrodotoxin (TTX). Inhibition of Na+ channel inactivation by veratridine (100 microM) evoked a [Na+]i increase of 47.1 mM in 44% of stellate and 9.7 mM in 64% of nonstellate astrocytes. About 30% of cells reacted to veratridine with a [Na+]i decrease of approximately 2 mM. Qualitatively similar [Na+]i changes were caused by aconitine. The effects of veratridine were blocked by TTX, amplified by (alpha-)scorpion toxin and usually were readily reversible. Veratridine-induced [Na+]i increases were reduced upon membrane depolarization with elevated extracellular [K+]. Recovery to baseline [Na+]i was unaltered during blocking of K+ channels with 4-aminopyridine. [Na+]i increases evoked by the ionotropic non-N-methyl--aspartate receptor agonist kainate were not altered by TTX. Our results indicate that influx of Na+ via voltage- gated Na+ channels is not a prerequisite for glial Na+,K+-ATPase activity in spinal cord astrocytes at rest nor does it seem to be involved in [Na+]i increases evoked by kainate. During pharmacological inhibition of Na+ channel inactivation, however, Na+ channels can serve as prominent pathways of Na+ influx and mediate large perturbations in [Na+]i, suggesting that Na+ channel inactivation plays an important functional role in these cells.
Collapse
Affiliation(s)
- C R Rose
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut 06520, USA
| | | | | |
Collapse
|
20
|
Abstract
Action potential generation and Na+ currents were studied in B104 neuroblastoma cells in vitro using the whole-cell patch-clamp method in voltage-clamp and current-clamp mode. Action potential-like responses were elicited in 38 of 42 cells, with a threshold close to -55 mV for depolarizing stimuli, and -56 mV for anode-break stimuli. Response amplitudes were larger when cells were held at more negative prepulse potentials, and were well fit by a Boltzmann distribution with a midpoint of approx. -75 mV, close to the V1/2 for Na+ current steady-state inactivation in these cells. Cells displaying action potential-like responses exhibited a peak Na+ current density of 133 +/- 0.14 pA/pF (range, 10.2-296.2 pA/pF) and a low gK:gNa ratio (0.0067 +/- 0.0023). Exposure to 0.1 mM Cd2+ did not block the generation of action potential-like responses in B104 cells, while 1 microM TTX abolished the responses. We conclude that low densities of Na+ channels (< 3/microns2, and < 1/micron2 in some cells) can support the generation of action potential-like responses in B104 cells if they are held at hyperpolarized levels to remove inactivation. The low leak and K+ conductance of these cells may contribute to their ability to generate action potential-like responses under these circumstances.
Collapse
Affiliation(s)
- X Q Gu
- Department of Neurology, Yale Medical School, New Haven, CT 06510, USA
| | | |
Collapse
|
21
|
Waxman SG, Black JA. Expression of mRNA for a sodium channel in subfamily 2 in spinal sensory neurons. Neurochem Res 1996; 21:395-401. [PMID: 8734431 DOI: 10.1007/bf02527702] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
RNA blot analysis and non-isotopic in situ hybridization cytochemistry were used to study the expression of the mRNA for the glial sodium channel NaG, belonging to Na+ channel subfamily 2, in rat dorsal root ganglia (DRG). mRNA hybridizing at high stringency with an antisense riboprobe against the NaG sequence was observed in both Schwann cells and spinal sensory neurons in situ within DRG, but was expressed at higher levels in the latter. In contrast, hybridization was not detectable in neurons within hippocampus, cerebellum and spinal cord. The expression of the mRNA hybridizing with the NaG probe appears to be developmentally regulated in both Schwann cells and DRG neurons, with levels increasing as development proceeds. Thus, in addition to the mRNAs for types I and II/IIA alpha-subunits and beta 1-subunit in DRG neurons and types II/IIA and III alpha-subunits beta 1-subunit in Schwann cells, the mRNA for an additional sodium channel belonging to subfamily 2 is expressed in these cells in situ.
Collapse
Affiliation(s)
- S G Waxman
- Department of Neurology, Yale School of Medicine, New Haven, CT 06510, USA
| | | |
Collapse
|