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ELBini I, Neili NE. Potassium channels at the crossroads of neuroinflammation and myelination in experimental models of multiple sclerosis. Biochem Biophys Res Commun 2023; 653:140-146. [PMID: 36870238 DOI: 10.1016/j.bbrc.2023.02.066] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/16/2023] [Accepted: 02/23/2023] [Indexed: 03/06/2023]
Abstract
Multiple sclerosis (MS) is a chronic demyelinating disease of the central nervous system (CNS), characterized by the presence of localized demyelinating lesions accompanied by an inflammatory reaction, evidently leading to neurodegeneration. A number of ion channels have been implicated in the progression of MS, most notably in cell types involved in the immune response. In the present study, we investigated the implication of two ion channel isoforms, Kv1.1 and Kv1.3, in experimental models of neuroinflammation and demyelination. Immunohistochemical staining of brain sections from the mouse cuprizone model displayed high levels Kv1.3 expression. In an astroglial cellular model of inflammation, stimulation with LPS resulted also in a higher expression of Kv1.1 and Kv1.3, while the introduction of 4-Aminopyridine (4-AP) exacerbated the release of pro-inflammatory chemokine CXCL10. In the oligodendroglial cellular model of demyelination, the alteration in expression levels of Kv1.1 and Kv1.3 may be correlated with that of MBP levels. Indirect co-culture was attempted to further understand the communication between astrocytes and oligodendrocytes, The addition of reactive astrocytes' secretome significantly inhibited the production of MBP, this inhibition was accompanied by an alteration in the expression of Kv1.1 and Kv1.3. The addition of 4-AP in this case did not alleviate the decrease in MBP production. In conclusion, the use of 4-AP generated controversial results, suggesting 4-AP may be used in the early stages of the disease or in the remission phases to stimulate myelination, yet in induced toxic inflammatory environment, 4-AP exacerbated this effect.
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Affiliation(s)
- Ines ELBini
- Laboratoire des Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, 1002, Tunisia.
| | - Nour-Elhouda Neili
- Laboratoire des Biomolécules, Venins et Applications Théranostiques (LR20IPT01), Institut Pasteur de Tunis, Université de Tunis El Manar, Tunis, 1002, Tunisia.
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2
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Molecular Mechanisms in the Vascular and Nervous Systems following Traumatic Spinal Cord Injury. LIFE (BASEL, SWITZERLAND) 2022; 13:life13010009. [PMID: 36675958 PMCID: PMC9866624 DOI: 10.3390/life13010009] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 11/26/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
Traumatic spinal cord injury (SCI) induces various complex pathological processes that cause physical impairment and psychological devastation. The two phases of SCI are primary mechanical damage (the immediate result of trauma) and secondary injury (which occurs over a period of minutes to weeks). After the mechanical impact, vascular disruption, inflammation, demyelination, neuronal cell death, and glial scar formation occur during the acute phase. This sequence of events impedes nerve regeneration. In the nervous system, various extracellular secretory factors such as neurotrophic factors, growth factors, and cytokines are involved in these events. In the vascular system, the blood-spinal cord barrier (BSCB) is damaged, allowing immune cells to infiltrate the parenchyma. Later, endogenous angiogenesis is promoted during the subacute phase. In this review, we describe the roles of secretory factors in the nervous and vascular systems following traumatic SCI, and discuss the outcomes of their therapeutic application in traumatic SCI.
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Kostadinova I, Landzhov B, Marinov L, Vezenkov L, Danchev N. Neuroprotective effect of newly synthesized 4-aminopyridine derivatives on cuprizone-induced demyelination in mice-a behavioral and immunohistochemical study. Amino Acids 2021; 53:1279-1286. [PMID: 34240251 DOI: 10.1007/s00726-021-03035-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 06/30/2021] [Indexed: 11/30/2022]
Abstract
The aim of this study was to assess the effect of newly synthesized derivatives of 4-aminopyridine (4-AP) on cuprizone-induced model of brain demyelination in mice. 4-AP is already approved for the treatment of walking difficulties in patients with multiple sclerosis. The model of demyelination was carried out by the administration of cuprizone to the drinking water of the experimental mice. Besides cuprizone, 4-AP derivatives and 4-AP were administered to the groups in order to assess their protective effect on the demyelination. We used immunohistochemistry for visualization of changes in corpus callosum. Memory storage processes were also assessed with the passive avoidance test on the last two days of the experiment. The experimental mice treated with compounds 4b and 4c increased significantly their latency time on the second day in comparison to the control group which indicated an improved memory process. The number of mature oligodendrocytes in the groups treated with compounds 4b, 4c and 4-AP is closer to those in the control group. The results of our studies showed that the newly synthesized compounds 4b and 4c reverse the effect of cuprizone. These groups also showed increased latency time in the passive avoidance test in comparison to the control group.
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Affiliation(s)
- Ivanka Kostadinova
- Department of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000, Sofia, Bulgaria.
| | - Boycho Landzhov
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, Medical University of Sofia, 2 Zdrave Str., 1431, Sofia, Bulgaria
| | - Lyubomir Marinov
- Department of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000, Sofia, Bulgaria
| | - Lyubomir Vezenkov
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 8 St. Kliment Ohridski Blvd., 1756, Sofia, Bulgaria
| | - Nikolai Danchev
- Department of Pharmacology, Pharmacotherapy and Toxicology, Faculty of Pharmacy, Medical University of Sofia, 2 Dunav Str., 1000, Sofia, Bulgaria
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Leussink VI, Montalban X, Hartung HP. Restoring Axonal Function with 4-Aminopyridine: Clinical Efficacy in Multiple Sclerosis and Beyond. CNS Drugs 2018; 32:637-651. [PMID: 29992409 DOI: 10.1007/s40263-018-0536-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The oral potassium channel blocker 4-aminopyridine has been used in various neurological conditions for decades. Numerous case reports and studies have supported its clinical efficacy in ameliorating the clinical presentation of certain neurological disorders. However, its short half-life, erratic drug levels, and safety-related dose restrictions limited its use as a self-compounded drug in clinical practice. This changed with the introduction of a prolonged-release formulation, which was successfully tested in patients with multiple sclerosis. It was fully approved by the US FDA in January 2010 but initially received only conditional approval from the European Medicines Agency (EMA) in July 2011. After additional clinical studies, this conditional approval was changed to unrestricted approval in August 2017. This article reviews and discusses these recent studies and places aminopyridines and their clinical utility into the context of a broader spectrum of neurological disorders, where clinical efficacy has been suggested. In 2010, prolonged-release 4-aminopyridine became the first drug specifically licensed to improve walking in patients with multiple sclerosis. About one-third of patients across disease courses benefit from this treatment. In addition, various reports indicate clinical efficacy beyond multiple sclerosis, which may broaden its use in clinical practice.
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Affiliation(s)
| | - Xavier Montalban
- Servei de Neurologia-Neuroimmunologia, Centre d'Esclerosi Múltiple de Catalunya (Cemcat), Hospital Universitario Vall d'Hebron, Barcelona, Spain.,St. Michael's Hospital, University of Toronto, Toronto, Canada
| | - Hans-Peter Hartung
- Department of Neurology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany.
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Fan B, Wei Z, Yao X, Shi G, Cheng X, Zhou X, Zhou H, Ning G, Kong X, Feng S. Microenvironment Imbalance of Spinal Cord Injury. Cell Transplant 2018; 27:853-866. [PMID: 29871522 PMCID: PMC6050904 DOI: 10.1177/0963689718755778] [Citation(s) in RCA: 278] [Impact Index Per Article: 46.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Spinal cord injury (SCI), for which there currently is no cure, is a heavy burden on
patient physiology and psychology. The microenvironment of the injured spinal cord is
complicated. According to our previous work and the advancements in SCI research,
‘microenvironment imbalance’ is the main cause of the poor regeneration and recovery of
SCI. Microenvironment imbalance is defined as an increase in inhibitory factors and
decrease in promoting factors for tissues, cells and molecules at different times and
spaces. There are imbalance of hemorrhage and ischemia, glial scar formation,
demyelination and re-myelination at the tissue’s level. The cellular level imbalance
involves an imbalance in the differentiation of endogenous stem cells and the
transformation phenotypes of microglia and macrophages. The molecular level includes an
imbalance of neurotrophic factors and their pro-peptides, cytokines, and chemokines. The
imbalanced microenvironment of the spinal cord impairs regeneration and functional
recovery. This review will aid in the understanding of the pathological processes involved
in and the development of comprehensive treatments for SCI.
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Affiliation(s)
- Baoyou Fan
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Zhijian Wei
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Xue Yao
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Guidong Shi
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Xin Cheng
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Xianhu Zhou
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Hengxing Zhou
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Guangzhi Ning
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
| | - Xiaohong Kong
- 2 Laboratory of Medical Molecular Virology, School of Medicine, Nankai University, Tianjin, China
| | - Shiqing Feng
- 1 National Spinal Cord Injury International Cooperation Base, Department of Orthopaedics, Tianjin Medical University General Hospital, Tianjin, China
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Dukala DE, Soliven B. S1P1deletion in oligodendroglial lineage cells: Effect on differentiation and myelination. Glia 2015; 64:570-82. [DOI: 10.1002/glia.22949] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 10/14/2015] [Accepted: 11/17/2015] [Indexed: 01/21/2023]
Affiliation(s)
- Danuta E. Dukala
- Department of Neurology; the University of Chicago; Chicago Illinois
| | - Betty Soliven
- Department of Neurology; the University of Chicago; Chicago Illinois
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Alizadeh A, Dyck SM, Karimi-Abdolrezaee S. Myelin damage and repair in pathologic CNS: challenges and prospects. Front Mol Neurosci 2015; 8:35. [PMID: 26283909 PMCID: PMC4515562 DOI: 10.3389/fnmol.2015.00035] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2015] [Accepted: 07/06/2015] [Indexed: 12/28/2022] Open
Abstract
Injury to the central nervous system (CNS) results in oligodendrocyte cell death and progressive demyelination. Demyelinated axons undergo considerable physiological changes and molecular reorganizations that collectively result in axonal dysfunction, degeneration and loss of sensory and motor functions. Endogenous adult oligodendrocyte precursor cells and neural stem/progenitor cells contribute to the replacement of oligodendrocytes, however, the extent and quality of endogenous remyelination is suboptimal. Emerging evidence indicates that optimal remyelination is restricted by multiple factors including (i) low levels of factors that promote oligodendrogenesis; (ii) cell death among newly generated oligodendrocytes, (iii) inhibitory factors in the post-injury milieu that impede remyelination, and (iv) deficient expression of key growth factors essential for proper re-construction of a highly organized myelin sheath. Considering these challenges, over the past several years, a number of cell-based strategies have been developed to optimize remyelination therapeutically. Outcomes of these basic and preclinical discoveries are promising and signify the importance of remyelination as a mechanism for improving functions in CNS injuries. In this review, we provide an overview on: (1) the precise organization of myelinated axons and the reciprocal axo-myelin interactions that warrant properly balanced physiological activities within the CNS; (2) underlying cause of demyelination and the structural and functional consequences of demyelination in axons following injury and disease; (3) the endogenous mechanisms of oligodendrocyte replacement; (4) the modulatory role of reactive astrocytes and inflammatory cells in remyelination; and (5) the current status of cell-based therapies for promoting remyelination. Careful elucidation of the cellular and molecular mechanisms of demyelination in the pathologic CNS is a key to better understanding the impact of remyelination for CNS repair.
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Affiliation(s)
- Arsalan Alizadeh
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg MB, Canada
| | - Scott M Dyck
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg MB, Canada
| | - Soheila Karimi-Abdolrezaee
- Regenerative Medicine Program, Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Faculty of Health Sciences, College of Medicine, University of Manitoba, Winnipeg MB, Canada
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Bagchi B, Al-Sabi A, Kaza S, Scholz D, O'Leary VB, Dolly JO, Ovsepian SV. Disruption of myelin leads to ectopic expression of K(V)1.1 channels with abnormal conductivity of optic nerve axons in a cuprizone-induced model of demyelination. PLoS One 2014; 9:e87736. [PMID: 24498366 PMCID: PMC3912067 DOI: 10.1371/journal.pone.0087736] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Accepted: 12/30/2013] [Indexed: 11/19/2022] Open
Abstract
The molecular determinants of abnormal propagation of action potentials along axons and ectopic conductance in demyelinating diseases of the central nervous system, like multiple sclerosis (MS), are poorly defined. Widespread interruption of myelin occurs in several mouse models of demyelination, rendering them useful for research. Herein, considerable myelin loss is shown in the optic nerves of cuprizone-treated demyelinating mice. Immuno-fluorescence confocal analysis of the expression and distribution of voltage-activated K⁺ channels (K(V)1.1 and 1.2 α subunits) revealed their spread from typical juxta-paranodal (JXP) sites to nodes in demyelinated axons, albeit with a disproportionate increase in the level of K(V)1.1 subunit. Functionally, in contrast to monophasic compound action potentials (CAPs) recorded in controls, responses derived from optic nerves of cuprizone-treated mice displayed initial synchronous waveform followed by a dispersed component. Partial restoration of CAPs by broad spectrum (4-aminopyridine) or K(V)1.1-subunit selective (dendrotoxin K) blockers of K⁺ currents suggest enhanced K(V)1.1-mediated conductance in the demyelinated optic nerve. Biophysical profiling of K⁺ currents mediated by recombinant channels comprised of different K(V)1.1 and 1.2 stoichiometries revealed that the enrichment of K(V)1 channels K(V)1.1 subunit endows a decrease in the voltage threshold and accelerates the activation kinetics. Together with the morphometric data, these findings provide important clues to a molecular basis for temporal dispersion of CAPs and reduced excitability of demyelinated optic nerves, which could be of potential relevance to the patho-physiology of MS and related disorders.
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Affiliation(s)
- Bandita Bagchi
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - Ahmed Al-Sabi
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - Seshu Kaza
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - Dimitri Scholz
- Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Valerie B. O'Leary
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
| | - J. Oliver Dolly
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
- * E-mail: (SVO); (JOD)
| | - Saak V. Ovsepian
- International Centre for Neurotherapeutics, Dublin City University, Glasnevin, Dublin, Republic of Ireland
- Department of Biotechnology, Dublin City University, Glasnevin, Dublin, Republic of Ireland
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Ludwig-Maximilians-Universität München, Zentrum für Neuropathologie, Feodor-Lynen-Str. 23, Munich, Germany
- * E-mail: (SVO); (JOD)
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Kegler K, Imbschweiler I, Ulrich R, Kovermann P, Fahlke C, Deschl U, Kalkuhl A, Baumgärnter W, Wewetzer K. CNS Schwann cells display oligodendrocyte precursor-like potassium channel activation and antigenic expression in vitro. J Neural Transm (Vienna) 2014; 121:569-81. [PMID: 24487976 DOI: 10.1007/s00702-014-1163-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 01/18/2014] [Indexed: 12/14/2022]
Abstract
Central nervous system (CNS) injury triggers production of myelinating Schwann cells from endogenous oligodendrocyte precursors (OLPs). These CNS Schwann cells may be attractive candidates for novel therapeutic strategies aiming to promote endogenous CNS repair. However, CNS Schwann cells have been so far mainly characterized in situ regarding morphology and marker expression, and it has remained enigmatic whether they display functional properties distinct from peripheral nervous system (PNS) Schwann cells. Potassium channels (K+) have been implicated in progenitor and glial cell proliferation after injury and may, therefore, represent a suitable pharmacological target. In the present study, we focused on the function and expression of voltage-gated K+ channels Kv(1-12) and accessory β-subunits in purified adult canine CNS and PNS Schwann cell cultures using electrophysiology and microarray analysis and characterized their antigenic phenotype. We show here that K+ channels differed significantly in both cell types. While CNS Schwann cells displayed prominent K D-mediated K+ currents, PNS Schwann cells elicited K(D-) and K(A-type) K+ currents. Inhibition of K+ currents by TEA and Ba2+ was more effective in CNS Schwann cells. These functional differences were not paralleled by differential mRNA expression of Kv(1-12) and accessory β-subunits. However, O4/A2B5 and GFAP expressions were significantly higher and lower, respectively, in CNS than in PNS Schwann cells. Taken together, this is the first evidence that CNS Schwann cells display specific properties not shared by their peripheral counterpart. Both Kv currents and increased O4/A2B5 expression were reminiscent of OLPs suggesting that CNS Schwann cells retain OLP features during maturation.
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Affiliation(s)
- Kristel Kegler
- Department of Pathology, University of Veterinary Medicine, Bünteweg 17, 30559, Hannover, Germany
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10
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K(V)7/KCNQ channels are functionally expressed in oligodendrocyte progenitor cells. PLoS One 2011; 6:e21792. [PMID: 21750731 PMCID: PMC3130044 DOI: 10.1371/journal.pone.0021792] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 06/12/2011] [Indexed: 11/26/2022] Open
Abstract
Background KV7/KCNQ channels are widely expressed in neurons and they have multiple important functions, including control of excitability, spike afterpotentials, adaptation, and theta resonance. Mutations in KCNQ genes have been demonstrated to associate with human neurological pathologies. However, little is known about whether KV7/KCNQ channels are expressed in oligodendrocyte lineage cells (OLCs) and what their functions in OLCs. Methods and Findings In this study, we characterized KV7/KCNQ channels expression in rat primary cultured OLCs by RT-PCR, immunostaining and electrophysiology. KCNQ2-5 mRNAs existed in all three developmental stages of rat primary cultured OLCs. KV7/KCNQ proteins were also detected in oligodendrocyte progenitor cells (OPCs, early developmental stages of OLCs) of rat primary cultures and cortex slices. Voltage-clamp recording revealed that the IM antagonist XE991 significantly reduced KV7/KCNQ channel current (IK(Q)) in OPCs but not in differentiated oligodendrocytes. In addition, inhibition of KV7/KCNQ channels promoted OPCs motility in vitro. Conclusions These findings showed that KV7/KCNQ channels were functionally expressed in rat primary cultured OLCs and might play an important role in OPCs functioning in physiological or pathological conditions.
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11
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Tegla CA, Cudrici C, Rozycka M, Soloviova K, Ito T, Singh AK, Khan A, Azimzadeh P, Andrian-Albescu M, Khan A, Niculescu F, Rus V, Judge SIV, Rus H. C5b-9-activated, K(v)1.3 channels mediate oligodendrocyte cell cycle activation and dedifferentiation. Exp Mol Pathol 2011; 91:335-45. [PMID: 21540025 DOI: 10.1016/j.yexmp.2011.04.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 04/13/2011] [Indexed: 12/11/2022]
Abstract
Voltage-gated potassium (K(v)) channels play an important role in the regulation of growth factor-induced cell proliferation. We have previously shown that cell cycle activation is induced in oligodendrocytes (OLGs) by complement C5b-9, but the role of K(v) channels in these cells had not been investigated. Differentiated OLGs were found to express K(v)1.4 channels, but little K(v)1.3. Exposure of OLGs to C5b-9 modulated K(v)1.3 functional channels and increased protein expression, whereas C5b6 had no effect. Pretreatment with the recombinant scorpion toxin rOsK-1, a highly selective K(v)1.3 inhibitor, blocked the expression of K(v)1.3 induced by C5b-9. rOsK-1 inhibited Akt phosphorylation and activation by C5b-9 but had no effect on ERK1 activation. These data strongly suggest a role for K(v)1.3 in controlling the Akt activation induced by C5b-9. Since Akt plays a major role in C5b-9-induced cell cycle activation, we also investigated the effect of inhibiting K(v)1.3 channels on DNA synthesis. rOsK-1 significantly inhibited the DNA synthesis induced by C5b-9 in OLG, indicating that K(v)1.3 plays an important role in the C5b-9-induced cell cycle. In addition, C5b-9-mediated myelin basic protein and proteolipid protein mRNA decay was completely abrogated by inhibition of K(v)1.3 expression. In the brains of multiple sclerosis patients, C5b-9 co-localized with NG2(+) OLG progenitor cells that expressed K(v)1.3 channels. Taken together, these data suggest that K(v)1.3 channels play an important role in controlling C5b-9-induced cell cycle activation and OLG dedifferentiation, both in vitro and in vivo.
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Affiliation(s)
- Cosmin A Tegla
- Department of Neurology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
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12
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Kim HJ, Miron VE, Dukala D, Proia RL, Ludwin SK, Traka M, Antel JP, Soliven B. Neurobiological effects of sphingosine 1‐phosphate receptor modulation in the cuprizone model. FASEB J 2011; 25:1509-18. [DOI: 10.1096/fj.10-173203] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Hye Jung Kim
- Department of NeurologyUniversity of ChicagoChicagoIllinoisUSA
| | | | - Danuta Dukala
- Department of NeurologyUniversity of ChicagoChicagoIllinoisUSA
| | - Richard L. Proia
- Genetics of Development and Disease BranchNational Institutes of HealthMarylandUSA
| | - Samuel K. Ludwin
- Department of NeuropathologyQueen's UniversityKingstonOntarioCanada
| | - Maria Traka
- Department of NeurologyUniversity of ChicagoChicagoIllinoisUSA
| | - Jack P. Antel
- Department of NeuroimmunologyMcGill UniversityMontrealQuebecCanada
| | - Betty Soliven
- Department of NeurologyUniversity of ChicagoChicagoIllinoisUSA
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13
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Vucic S, Burke D, Kiernan MC. Fatigue in multiple sclerosis: mechanisms and management. Clin Neurophysiol 2010; 121:809-17. [PMID: 20100665 DOI: 10.1016/j.clinph.2009.12.013] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Revised: 12/03/2009] [Accepted: 12/03/2009] [Indexed: 12/19/2022]
Abstract
Multiple sclerosis [MS] is a chronic immune-mediated disorder of the central nervous system [CNS]. Fatigue may be a debilitating symptom in MS patients, adversely impacting on their quality of life. Clinically, fatigue may manifest as exhaustion, lack of energy, increased somnolence, or worsening of MS symptoms. Activity and heat typically serve to exacerbate symptoms of fatigue. There is now strong evidence to suggest that fatigue results from reduced voluntary activation of muscles by means of central mechanisms. Given that axonal demyelination is a pathological hallmark of MS, activity-dependent conduction block [ADCB] has been proposed as a mechanism underlying fatigue in MS. This ADCB results from axonal membrane hyperpolarization, mediated by the Na(+)/K(+) electrogenic pump, with conduction failure precipitated in demyelinated axons with a reduced safety factor of impulse transmission. In addition, Na(+)/K(+) pump dysfunction, as reported in MS, may induce a depolarizing conduction block associated with inactivation of Na(+) channels. These processes may induce secondary effects including axonal degeneration triggered by raised levels of intracellular Ca(2+) through reverse operation of the Na(+)-Ca(2+) exchanger. Restoration of normal conduction in demyelinated axons with selective channel blockers improves fatigue and may yet prove useful as a neuroprotective strategy, in preventing secondary axonal degeneration and consequent functional impairment.
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Affiliation(s)
- Steve Vucic
- Department of Neurology, Westmead Hospital and Western Clinical School, University of Sydney, Sydney, NSW, Australia
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14
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Kim H, Jo S, Song HJ, Park ZY, Park CS. Myelin basic protein as a binding partner and calmodulin adaptor for the BKCa channel. Proteomics 2007; 7:2591-602. [PMID: 17610306 DOI: 10.1002/pmic.200700185] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The activity and localization of large-conductance Ca2+ -activated K+ (BKCa) channels are known to be modulated by several different proteins. Although many binding partners have been identified via yeast two-hybrid screening, this method may not detect certain classes of interacting proteins such as low affinity binding proteins or multi-component protein complexes. In this study, we employed mass spectrometry to identify proteins that interact with BKCa channels. We expressed and purified the 'tail domain' of the rat BKCa channel alpha-subunit, a 54-kDa region that is crucial for expression and functional activity of the channel. Using rat brain lysate and purified 'tail domain', we identified several novel proteins that interact with the BKCa channel. These included the myelin basic protein (MBP), upon which we performed subsequent biochemical and electrophysiological studies. Interaction between the BKCa channel and MBP was confirmed in vivo and in vitro. MBP co-expression affected the Ca2+ -dependent activation of the BKCa channel by increasing its Ca2+ sensitivity. Moreover, we showed that calmodulin (CaM) interacts with the BKCa channel via MBP. Since CaM is a key regulator of many Ca2+ -dependent processes, it may be recruited by MBP to the vicinity of the BKCa channel, modulating its functional activity.
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Affiliation(s)
- Hyunyoung Kim
- Department Life Science, Gwangju Institute of Science and Technology (GIST), Gwangju, Korea
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Toma JS, McPhail LT, Ramer MS. Differential RIP antigen (CNPase) expression in peripheral ensheathing glia. Brain Res 2006; 1137:1-10. [PMID: 17229407 DOI: 10.1016/j.brainres.2006.12.053] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Revised: 12/07/2006] [Accepted: 12/14/2006] [Indexed: 01/06/2023]
Abstract
The RIP monoclonal antibody is commonly used to identify oligodendrocytes. Recently, the RIP antigen was identified as 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), a known non-compact myelin protein [Watanabe, M., Sakurai, Y., Ichinose, T., Aikawa, Y., Kotani, M., Itoh, K., 2006. Monoclonal antibody Rip specifically recognizes 2',3'-cyclic nucleotide 3'-phosphodiesterase in oligodendrocytes. J. Neurosci. Res. 84, 525-533]. In the present study we characterize normal and axotomy-induced changes in RIP immunoreactivity in peripheral glia. In myelinating Schwann cells, RIP demarcated paranodal regions of myelinated axons and clearly defined Schmidt-Lantermann incisures. Surprisingly, RIP immunoreactivity was not confined to myelinating glia. Robust RIP immunoreactivity was present in Remak bundles in mixed nerves and in sympathetic ganglia and grey rami. Following peripheral nerve injury, RIP immunoreactivity was redistributed diffusely throughout de-differentiating Schwann cell cytoplasm. In uninjured rats, low levels of RIP immunoreactivity were detectable in satellite cells surrounding dorsal root ganglion (DRG) neurons and in terminal Schwann cells at neuromuscular junctions. This pattern suggested a correlation between RIP immunoreactivity and the amount of axon-glial contact. We therefore injured the L5 spinal nerve to induce sympathetic sprouting and pericellular basket formation in the DRG, and asked whether relatively RIP-negative satellite glia, which normally contact only neuronal somata, would upregulate the RIP antigen upon contact with sprouting sympathetic axons. All perineuronal sympathetic sprouts infiltrated heavily RIP-immunoreactive satellite cell sheaths. RIP immunoreactivity was absent from placode-derived olfactory ensheathing glia, indicating that the relationship between axon-glial contact and RIP-immunoreactivity is restricted to peripheral ensheathing glia of the neural crest-derived Schwann cell lineage.
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Affiliation(s)
- Jeremy S Toma
- International Collaboration on Repair Discoveries, The University of British Columbia, Rm. 2465, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4
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Tiwari-Woodruff S, Beltran-Parrazal L, Charles A, Keck T, Vu T, Bronstein J. K+ channel KV3.1 associates with OSP/claudin-11 and regulates oligodendrocyte development. Am J Physiol Cell Physiol 2006; 291:C687-98. [PMID: 16624990 DOI: 10.1152/ajpcell.00510.2005] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
K(+) channels are differentially expressed throughout oligodendrocyte (Olg) development. K(V)1 family voltage-sensitive K(+) channels have been implicated in proliferation and migration of Olg progenitor cell (OPC) stage, and inward rectifier K+ channels (K(IR))4.1 are required for OPC differentiation to myelin-forming Olg. In this report we have identified a Shaw family K(+) channel, K(V)3.1, that is involved in proliferation and migration of OPC and axon myelination. Application of anti-K(V)3.1 antibody or knockout of Kv3.1 gene decreased the sustained K(+) current component of OPC by 50% and 75%, respectively. In functional assays block of K(V)3.1-specific currents or knockout of Kv3.1 gene inhibited proliferation and migration of OPC. Adult Kv3.1 gene-knockout mice had decreased diameter of axons and decreased thickness of myelin in optic nerves compared with age-matched wild-type littermates. Additionally, K(V)3.1 was identified as an associated protein of Olg-specific protein (OSP)/claudin-11 via yeast two-hybrid analysis, which was confirmed by coimmunoprecipitation and coimmunohistochemistry. In summary, the K(V)3.1 K(+) current accounts for a significant component of the total K(+) current in cells of the Olg lineage and, in association with OSP/claudin-11, plays a significant role in OPC proliferation and migration and myelination of axons.
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Affiliation(s)
- Seema Tiwari-Woodruff
- UCLA Multiple Sclerosis Program, Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California 90095, USA.
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Aldskogius H. Repairing CNS myelin—astrocytes have to do their jobs. Exp Neurol 2005; 192:7-10. [PMID: 15698614 DOI: 10.1016/j.expneurol.2004.10.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2004] [Accepted: 10/20/2004] [Indexed: 12/24/2022]
Affiliation(s)
- Hakan Aldskogius
- Department of Neuroscience, Biomed Center, PO Box 587, Uppsala, SE-75123, Sweden.
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