1
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Ciotu CI, Kistner K, Kaindl U, Millesi F, Weiss T, Radtke C, Kremer A, Schmidt K, Fischer MJM. Schwann cell stimulation induces functional and structural changes in peripheral nerves. Glia 2023; 71:945-956. [PMID: 36495059 DOI: 10.1002/glia.24316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 11/19/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022]
Abstract
Signal propagation is the essential function of nerves. Lysophosphatidic acid 18:1 (LPA) allows the selective stimulation of calcium signaling in Schwann cells but not neurons. Here, the time course of slowing and amplitude reduction on compound action potentials due to LPA exposure was observed in myelinated and unmyelinated fibers of the mouse, indicating a clear change of axonal function. Teased nerve fiber imaging showed that Schwann cell activation is also present in axon-attached Schwann cells in freshly isolated peripheral rat nerves. The LPA receptor 1 was primarily localized at the cell extensions in isolated rat Schwann cells, suggesting a role in cell migration. Structural investigation of rat C-fibers demonstrated that LPA leads to an evagination of the axons from their Schwann cells. In A-fibers, the nodes of Ranvier appeared unchanged, but the Schmidt-Lanterman incisures were shortened and myelination reduced. The latter might increase leak current, reducing the potential spread to the next node of Ranvier and explain the changes in conduction velocity. The observed structural changes provide a plausible explanation for the functional changes in myelinated and unmyelinated axons of peripheral nerves and the reported sensory sensations such as itch and pain.
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Affiliation(s)
- Cosmin I Ciotu
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Katrin Kistner
- Institute of Physiology and Pathophysiology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Ulrich Kaindl
- Department of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Flavia Millesi
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Vienna, Austria
| | - Tamara Weiss
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Vienna, Austria
| | - Christine Radtke
- Department of Plastic, Reconstructive and Aesthetic Surgery, Medical University of Vienna, Vienna, Austria
| | - Andreas Kremer
- Department of Gastroenterology and Hepatology, University Hospital Zürich, Zürich, Switzerland
| | - Katy Schmidt
- Department of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria
| | - Michael J M Fischer
- Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria
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2
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Hsu LJ, Bertho M, Kiehn O. Deconstructing the modular organization and real-time dynamics of mammalian spinal locomotor networks. Nat Commun 2023; 14:873. [PMID: 36797254 PMCID: PMC9935527 DOI: 10.1038/s41467-023-36587-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/07/2023] [Indexed: 02/18/2023] Open
Abstract
Locomotion empowers animals to move. Locomotor-initiating signals from the brain are funneled through descending neurons in the brainstem that act directly on spinal locomotor circuits. Little is known in mammals about which spinal circuits are targeted by the command and how this command is transformed into rhythmicity in the cord. Here we address these questions leveraging a mouse brainstem-spinal cord preparation from either sex that allows locating the locomotor command neurons with simultaneous Ca2+ imaging of spinal neurons. We show that a restricted brainstem area - encompassing the lateral paragigantocellular nucleus (LPGi) and caudal ventrolateral reticular nucleus (CVL) - contains glutamatergic neurons which directly initiate locomotion. Ca2+ imaging captures the direct LPGi/CVL locomotor initiating command in the spinal cord and visualizes spinal glutamatergic modules that execute the descending command and its transformation into rhythmic locomotor activity. Inhibitory spinal networks are recruited in a distinctly different pattern. Our study uncovers the principal logic of how spinal circuits implement the locomotor command using a distinct modular organization.
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Affiliation(s)
- Li-Ju Hsu
- Department of Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark.,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Maëlle Bertho
- Department of Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark.,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden
| | - Ole Kiehn
- Department of Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Department of Neuroscience, Karolinska Institutet, 171 77, Stockholm, Sweden.
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3
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Kole K, Voesenek BJB, Brinia ME, Petersen N, Kole MHP. Parvalbumin basket cell myelination accumulates axonal mitochondria to internodes. Nat Commun 2022; 13:7598. [PMID: 36494349 PMCID: PMC9734141 DOI: 10.1038/s41467-022-35350-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 11/30/2022] [Indexed: 12/13/2022] Open
Abstract
Parvalbumin-expressing (PV+) basket cells are fast-spiking inhibitory interneurons that exert critical control over local circuit activity and oscillations. PV+ axons are often myelinated, but the electrical and metabolic roles of interneuron myelination remain poorly understood. Here, we developed viral constructs allowing cell type-specific investigation of mitochondria with genetically encoded fluorescent probes. Single-cell reconstructions revealed that mitochondria selectively cluster to myelinated segments of PV+ basket cells, confirmed by analyses of a high-resolution electron microscopy dataset. In contrast to the increased mitochondrial densities in excitatory axons cuprizone-induced demyelination abolished mitochondrial clustering in PV+ axons. Furthermore, with genetic deletion of myelin basic protein the mitochondrial clustering was still observed at internodes wrapped by noncompacted myelin, indicating that compaction is dispensable. Finally, two-photon imaging of action potential-evoked calcium (Ca2+) responses showed that interneuron myelination attenuates both the cytosolic and mitochondrial Ca2+ transients. These findings suggest that oligodendrocyte ensheathment of PV+ axons assembles mitochondria to branch selectively fine-tune metabolic demands.
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Affiliation(s)
- Koen Kole
- grid.418101.d0000 0001 2153 6865Axonal Signaling Group, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Bas J. B. Voesenek
- grid.418101.d0000 0001 2153 6865Axonal Signaling Group, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Maria E. Brinia
- grid.418101.d0000 0001 2153 6865Axonal Signaling Group, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands ,grid.5216.00000 0001 2155 0800Medical School, National Kapodistrian University of Athens, Athens, 11527 Greece
| | - Naomi Petersen
- grid.418101.d0000 0001 2153 6865Axonal Signaling Group, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Maarten H. P. Kole
- grid.418101.d0000 0001 2153 6865Axonal Signaling Group, Netherlands Institute for Neuroscience, Royal Netherlands Academy of Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands ,grid.5477.10000000120346234Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
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4
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A link between agrin signalling and Ca v3.2 at the neuromuscular junction in spinal muscular atrophy. Sci Rep 2022; 12:18960. [PMID: 36347955 PMCID: PMC9643518 DOI: 10.1038/s41598-022-23703-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 11/03/2022] [Indexed: 11/11/2022] Open
Abstract
SMN protein deficiency causes motoneuron disease spinal muscular atrophy (SMA). SMN-based therapies improve patient motor symptoms to variable degrees. An early hallmark of SMA is the perturbation of the neuromuscular junction (NMJ), a synapse between a motoneuron and muscle cell. NMJ formation depends on acetylcholine receptor (AChR) clustering triggered by agrin and its co-receptors lipoprotein receptor-related protein 4 (LRP4) and transmembrane muscle-specific kinase (MuSK) signalling pathway. We have previously shown that flunarizine improves NMJs in SMA model mice, but the mechanisms remain elusive. We show here that flunarizine promotes AChR clustering in cell-autonomous, dose- and agrin-dependent manners in C2C12 myotubes. This is associated with an increase in protein levels of LRP4, integrin-beta-1 and alpha-dystroglycan, three agrin co-receptors. Furthermore, flunarizine enhances MuSK interaction with integrin-beta-1 and phosphotyrosines. Moreover, the drug acts on the expression and splicing of Agrn and Cacna1h genes in a muscle-specific manner. We reveal that the Cacna1h encoded protein Cav3.2 closely associates in vitro with the agrin co-receptor LRP4. In vivo, it is enriched nearby NMJs during neonatal development and the drug increases this immunolabelling in SMA muscles. Thus, flunarizine modulates key players of the NMJ and identifies Cav3.2 as a new protein involved in the NMJ biology.
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5
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Long-term in vivo imaging of mouse spinal cord through an optically cleared intervertebral window. Nat Commun 2022; 13:1959. [PMID: 35414131 PMCID: PMC9005710 DOI: 10.1038/s41467-022-29496-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Accepted: 03/17/2022] [Indexed: 11/08/2022] Open
Abstract
The spinal cord accounts for the main communication pathway between the brain and the peripheral nervous system. Spinal cord injury is a devastating and largely irreversible neurological trauma, and can result in lifelong disability and paralysis with no available cure. In vivo spinal cord imaging in mouse models without introducing immunological artifacts is critical to understand spinal cord pathology and discover effective treatments. We developed a minimally invasive intervertebral window by retaining the ligamentum flavum to protect the underlying spinal cord. By introducing an optical clearing method, we achieve repeated two-photon fluorescence and stimulated Raman scattering imaging at subcellular resolution with up to 15 imaging sessions over 6-167 days and observe no inflammatory response. Using this optically cleared intervertebral window, we study neuron-glia dynamics following laser axotomy and observe strengthened contact of microglia with the nodes of Ranvier during axonal degeneration. By enabling long-term, repetitive, stable, high-resolution and inflammation-free imaging of mouse spinal cord, our method provides a reliable platform in the research aiming at interpretation of spinal cord physiology and pathology.
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6
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Schwarz JR. Function of K2P channels in the mammalian node of Ranvier. J Physiol 2021; 599:4427-4439. [PMID: 34425634 DOI: 10.1113/jp281723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/09/2021] [Indexed: 11/08/2022] Open
Abstract
In myelinated nerve fibres, action potentials are generated at nodes of Ranvier. These structures are located at interruptions of the myelin sheath, forming narrow gaps with small rings of axolemma freely exposed to the extracellular space. The mammalian node contains a high density of Na+ channels and K+ -selective leakage channels. Voltage-dependent Kv1 channels are only present in the juxta-paranode. Recently, the leakage channels have been identified as K2P channels (TRAAK, TREK-1). K2P channels are K+ -selective 'background' channels, characterized by outward rectification and their ability to be activated, e.g. by temperature, mechanical stretch or arachidonic acid. We are only beginning to elucidate the peculiar functions of nodal K2P channels. I will discuss two functions of the nodal K2P-mediated conductance. First, at body temperature K2P channels have a high open probability, thereby inducing a resting potential of about -85 mV. This negative resting potential reduces steady-state Na+ channel inactivation and ensures a large Na+ inward current upon a depolarizing stimulus. Second, the K2P conductance is involved in nodal action potential repolarization. The identification of nodal K2P channels is exciting since it shows that the nodal K+ conductance is not a fixed value but can be changed: it can be increased or decreased by a broad range of K2P modulators, thereby modulating, for example, the resting potential. The functional importance of nodal K2P channels will be exemplified by describing in more detail the function of the K2P conductance increase by raising the temperature from room temperature to 37°C.
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Affiliation(s)
- Jürgen R Schwarz
- Institute of Molecular Neurogenetics, Center for Molecular Neurobiology Hamburg (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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7
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Hanemaaijer NA, Popovic MA, Wilders X, Grasman S, Pavón Arocas O, Kole MH. Ca 2+ entry through Na V channels generates submillisecond axonal Ca 2+ signaling. eLife 2020; 9:54566. [PMID: 32553116 PMCID: PMC7380941 DOI: 10.7554/elife.54566] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 06/12/2020] [Indexed: 12/15/2022] Open
Abstract
Calcium ions (Ca2+) are essential for many cellular signaling mechanisms and enter the cytosol mostly through voltage-gated calcium channels. Here, using high-speed Ca2+ imaging up to 20 kHz in the rat layer five pyramidal neuron axon we found that activity-dependent intracellular calcium concentration ([Ca2+]i) in the axonal initial segment was only partially dependent on voltage-gated calcium channels. Instead, [Ca2+]i changes were sensitive to the specific voltage-gated sodium (NaV) channel blocker tetrodotoxin. Consistent with the conjecture that Ca2+ enters through the NaV channel pore, the optically resolved ICa in the axon initial segment overlapped with the activation kinetics of NaV channels and heterologous expression of NaV1.2 in HEK-293 cells revealed a tetrodotoxin-sensitive [Ca2+]i rise. Finally, computational simulations predicted that axonal [Ca2+]i transients reflect a 0.4% Ca2+ conductivity of NaV channels. The findings indicate that Ca2+ permeation through NaV channels provides a submillisecond rapid entry route in NaV-enriched domains of mammalian axons. Nerve cells communicate using tiny electrical impulses called action potentials. Special proteins termed ion channels produce these electric signals by allowing specific charged particles, or ions, to pass in or out of cells across its membrane. When a nerve cell ‘fires’ an action potential, specific ion channels briefly open to let in a surge of positively charged ions which electrify the cell. Action potentials begin in the same place in each nerve cell, at an area called the axon initial segment. The large number of sodium channels at this site kick-start the influx of positively charged sodium ions ensuring that every action potential starts from the same place. Previous research has shown that, when action potentials begin, the concentration of calcium ions at the axon initial segment also increases, but it was not clear which ion channels were responsible for this entry of calcium. Channels that are selective for calcium ions are the prime candidates for this process. However, research in squid nerve cells gave rise to an unexpected idea by suggesting that sodium channels may not exclusively let in sodium but also allow some calcium ions to pass through. Hanemaaijer, Popovic et al. therefore wanted to test the routes that calcium ions take and see whether the sodium channels in mammalian nerve cells are also permeable to calcium. Experiments using fluorescent dyes to track the concentration of calcium in rat and human nerve cells showed that calcium ions accumulated at the axon initial segment when action potentials fired. Most of this increase in calcium could be stopped by treating the neurons with a toxin that prevents sodium channels from opening. Electrical manipulations of the cells revealed that, in this context, the calcium ions were effectively behaving like sodium ions. Human kidney cells were then engineered to produce the sodium channel protein. This confirmed that calcium and sodium ions were indeed both passing through the same channel. These results shed new light on the relationship between calcium ions and sodium channels within the mammalian nervous system and that this interplay occurs at the axon initial segment of the cell. Genetic mutations that ‘nudge’ sodium channels towards favoring calcium entry are also found in patients with autism spectrum disorders, and so this new finding may contribute to our understanding of these conditions.
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Affiliation(s)
- Naomi Ak Hanemaaijer
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands.,Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Marko A Popovic
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Xante Wilders
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Sara Grasman
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Oriol Pavón Arocas
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Maarten Hp Kole
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands.,Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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8
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Sun SC, Ma D, Li MY, Zhang RX, Huang C, Huang HJ, Xie YZ, Wang ZJ, Liu J, Cai DC, Liu CX, Yang Q, Bao FX, Gong XL, Li JR, Hui Z, Wei XF, Zhong JM, Zhou WJ, Shang X, Zhang C, Liu XG, Tang BS, Xiong F, Xu XM. Mutations in C1orf194, encoding a calcium regulator, cause dominant Charcot-Marie-Tooth disease. Brain 2020; 142:2215-2229. [PMID: 31199454 DOI: 10.1093/brain/awz151] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/13/2019] [Accepted: 04/10/2019] [Indexed: 12/27/2022] Open
Abstract
Charcot-Marie-Tooth disease is a hereditary motor and sensory neuropathy exhibiting great clinical and genetic heterogeneity. Here, the identification of two heterozygous missense mutations in the C1orf194 gene at 1p21.2-p13.2 with Charcot-Marie-Tooth disease are reported. Specifically, the p.I122N mutation was the cause of an intermediate form of Charcot-Marie-Tooth disease, and the p.K28I missense mutation predominately led to the demyelinating form. Functional studies demonstrated that the p.K28I variant significantly reduced expression of the protein, but the p.I122N variant increased. In addition, the p.I122N mutant protein exhibited the aggregation in neuroblastoma cell lines and the patient's peroneal nerve. Either gain-of-function or partial loss-of-function mutations to C1ORF194 can specify different causal mechanisms responsible for Charcot-Marie-Tooth disease with a wide range of clinical severity. Moreover, a knock-in mouse model confirmed that the C1orf194 missense mutation p.I121N led to impairments in motor and neuromuscular functions, and aberrant myelination and axonal phenotypes. The loss of normal C1ORF194 protein altered intracellular Ca2+ homeostasis and upregulated Ca2+ handling regulatory proteins. These findings describe a novel protein with vital functions in peripheral nervous systems and broaden the causes of Charcot-Marie-Tooth disease, which open new avenues for the diagnosis and treatment of related neuropathies.
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Affiliation(s)
- Shun-Chang Sun
- Department of Clinical Laboratory, Ruijin Hospital North, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - Di Ma
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Mei-Yi Li
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Ru-Xu Zhang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Cheng Huang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Hua-Jie Huang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Yong-Zhi Xie
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Zhong-Ju Wang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Jun Liu
- Department of Neurology and Institute of Neurology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, P.R. China
| | - De-Cheng Cai
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Cui-Xian Liu
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Qi Yang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Fei-Xiang Bao
- Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, P.R. China
| | - Xiao-Li Gong
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Jie-Ru Li
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Zheng Hui
- Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Xiao-Feng Wei
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Jian-Mei Zhong
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Wan-Jun Zhou
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Xuan Shang
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China
| | - Cheng Zhang
- Department of Neurology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, P.R. China
| | - Xing-Guo Liu
- Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, P.R. China
| | - Bei-Sha Tang
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, Hunan 410008, P.R. China
| | - Fu Xiong
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou 510515, P.R. China.,Guangdong Provincial Key Laboratory of Single Cell Technology and Application, Guangzhou, Guangdong Province, P.R.China
| | - Xiang-Min Xu
- Department of Medical Genetics, School of Basic Medical Sciences, Southern Medical University, Guangzhou, P.R. China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou 510515, P.R. China.,Guangdong Provincial Key Laboratory of Single Cell Technology and Application, Guangzhou, Guangdong Province, P.R.China.,Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Southern Medical University, Guangzhou 510515, P.R. China
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9
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Carter MT, McMillan HJ, Tomin A, Weiss N. Compound heterozygous CACNA1H mutations associated with severe congenital amyotrophy. Channels (Austin) 2020; 13:153-161. [PMID: 31070086 PMCID: PMC6527065 DOI: 10.1080/19336950.2019.1614415] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Neuromuscular disorders encompass a wide range of conditions often associated with a genetic component. In the present study, we report a patient with severe infantile-onset amyotrophy in whom two compound heterozygous variants in the gene CACNA1H encoding for Cav3.2 T-type calcium channels were identified. Functional analysis of Cav3.2 variants revealed several alterations of the gating properties of the channel that were in general consistent with a loss-of-channel function. Taken together, these findings suggest that severe congenital amyoplasia may be related to CACNA1H and would represent a new phenotype associated with mutations in this gene.
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Affiliation(s)
- Melissa T Carter
- a Children's Hospital of Eastern Ontario Research Institute , University of Ottawa , Ottawa , Ontario , Canada
| | - Hugh J McMillan
- a Children's Hospital of Eastern Ontario Research Institute , University of Ottawa , Ottawa , Ontario , Canada
| | - Andriy Tomin
- b Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Prague , Czech Republic
| | - Norbert Weiss
- b Institute of Organic Chemistry and Biochemistry , Czech Academy of Sciences , Prague , Czech Republic
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10
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Stringer RN, Jurkovicova-Tarabova B, Huang S, Haji-Ghassemi O, Idoux R, Liashenko A, Souza IA, Rzhepetskyy Y, Lacinova L, Van Petegem F, Zamponi GW, Pamphlett R, Weiss N. A rare CACNA1H variant associated with amyotrophic lateral sclerosis causes complete loss of Ca v3.2 T-type channel activity. Mol Brain 2020; 13:33. [PMID: 32143681 PMCID: PMC7060640 DOI: 10.1186/s13041-020-00577-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 03/02/2020] [Indexed: 12/13/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the progressive loss of cortical, brain stem and spinal motor neurons that leads to muscle weakness and death. A previous study implicated CACNA1H encoding for Cav3.2 calcium channels as a susceptibility gene in ALS. In the present study, two heterozygous CACNA1H variants were identified by whole genome sequencing in a small cohort of ALS patients. These variants were functionally characterized using patch clamp electrophysiology, biochemistry assays, and molecular modeling. A previously unreported c.454GTAC > G variant produced an inframe deletion of a highly conserved isoleucine residue in Cav3.2 (p.ΔI153) and caused a complete loss-of-function of the channel, with an additional dominant-negative effect on the wild-type channel when expressed in trans. In contrast, the c.3629C > T variant caused a missense substitution of a proline with a leucine (p.P1210L) and produced a comparatively mild alteration of Cav3.2 channel activity. The newly identified ΔI153 variant is the first to be reported to cause a complete loss of Cav3.2 channel function. These findings add to the notion that loss-of-function of Cav3.2 channels associated with rare CACNA1H variants may be risk factors in the complex etiology of ALS.
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Affiliation(s)
- Robin N. Stringer
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam 2, 16610 Prague, Czech Republic
- Third Faculty of Medicine, Charles University, Prague, Czech Republic
| | | | - Sun Huang
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Omid Haji-Ghassemi
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Romane Idoux
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam 2, 16610 Prague, Czech Republic
| | - Anna Liashenko
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam 2, 16610 Prague, Czech Republic
| | - Ivana A. Souza
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Yuriy Rzhepetskyy
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam 2, 16610 Prague, Czech Republic
| | - Lubica Lacinova
- Center of Biosciences, Institute of Molecular Physiology and Genetics, Academy of Sciences, Bratislava, Slovakia
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
| | - Gerald W. Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Roger Pamphlett
- Discipline of Pathology, Brain and Mind Centre, The University of Sydney, Sydney, NSW Australia
| | - Norbert Weiss
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nam 2, 16610 Prague, Czech Republic
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11
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Cohen CCH, Popovic MA, Klooster J, Weil MT, Möbius W, Nave KA, Kole MHP. Saltatory Conduction along Myelinated Axons Involves a Periaxonal Nanocircuit. Cell 2020; 180:311-322.e15. [PMID: 31883793 PMCID: PMC6978798 DOI: 10.1016/j.cell.2019.11.039] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 08/24/2019] [Accepted: 11/27/2019] [Indexed: 11/30/2022]
Abstract
The propagation of electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or "jumping" action potentials across internodes, from one node of Ranvier to the next. The underlying electrical circuit, as well as the existence and role of submyelin conduction in saltatory conduction remain, however, elusive. Here, we made patch-clamp and high-speed voltage-calibrated optical recordings of potentials across the nodal and internodal axolemma of myelinated neocortical pyramidal axons combined with electron microscopy and experimentally constrained cable modeling. Our results reveal a nanoscale yet conductive periaxonal space, incompletely sealed at the paranodes, which separates the potentials across the low-capacitance myelin sheath and internodal axolemma. The emerging double-cable model reproduces the recorded evolution of voltage waveforms across nodes and internodes, including rapid nodal potentials traveling in advance of attenuated waves in the internodal axolemma, revealing a mechanism for saltation across time and space.
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Affiliation(s)
- Charles C H Cohen
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands; Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands
| | - Marko A Popovic
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Jan Klooster
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands
| | - Marie-Theres Weil
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Wiebke Möbius
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max-Planck-Institute for Experimental Medicine, Göttingen, Hermann-Rein-Strasse 3, 37075 Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany
| | - Maarten H P Kole
- Department of Axonal Signalling, Netherlands Institute for Neuroscience, Royal Netherlands Academy for Arts and Sciences, Meibergdreef 47, 1105 BA Amsterdam, the Netherlands; Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands.
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12
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Weiss N, Zamponi GW. Genetic T-type calcium channelopathies. J Med Genet 2020; 57:1-10. [PMID: 31217264 PMCID: PMC6929700 DOI: 10.1136/jmedgenet-2019-106163] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 05/02/2019] [Accepted: 05/18/2019] [Indexed: 12/13/2022]
Abstract
T-type channels are low-voltage-activated calcium channels that contribute to a variety of cellular and physiological functions, including neuronal excitability, hormone and neurotransmitter release as well as developmental aspects. Several human conditions including epilepsy, autism spectrum disorders, schizophrenia, motor neuron disorders and aldosteronism have been traced to variations in genes encoding T-type channels. In this short review, we present the genetics of T-type channels with an emphasis on structure-function relationships and associated channelopathies.
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Affiliation(s)
- Norbert Weiss
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Praha, Czech Republic
| | - Gerald W Zamponi
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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13
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Manganelli F, Parisi S, Nolano M, Miceli F, Tozza S, Pisciotta C, Iodice R, Provitera V, Cicatiello R, Zuchner S, Taglialatela M, Russo T, Santoro L. Insights into the pathogenesis of
ATP1A1
‐related CMT disease using patient‐specific iPSCs. J Peripher Nerv Syst 2019; 24:330-339. [DOI: 10.1111/jns.12357] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 11/06/2019] [Accepted: 11/06/2019] [Indexed: 12/18/2022]
Affiliation(s)
- Fiore Manganelli
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Silvia Parisi
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Naples “Federico II” Naples Italy
| | - Maria Nolano
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
- Department of NeurologyIstituti Clinici Scientifici Maugeri IRCCS, SpA SB Pavia Italy
| | - Francesco Miceli
- Section of Pharmacology, Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Stefano Tozza
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Chiara Pisciotta
- Rare Neurodegenerative and Neurometabolic Disease UnitFondazione IRCCS Istituto Neurologico Carlo Besta Milan Italy
| | - Rosa Iodice
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Vincenzo Provitera
- Department of NeurologyIstituti Clinici Scientifici Maugeri IRCCS, SpA SB Pavia Italy
| | - Rita Cicatiello
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Naples “Federico II” Naples Italy
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human GenomicsUniversity of Miami Miller School of Medicine Miami Florida
| | - Maurizio Taglialatela
- Section of Pharmacology, Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
| | - Tommaso Russo
- Department of Molecular Medicine and Medical BiotechnologiesUniversity of Naples “Federico II” Naples Italy
| | - Lucio Santoro
- Department of Neuroscience, Reproductive Sciences and OdontostomatologyUniversity of Naples “Federico II” Naples Italy
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14
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Toomey LM, Bartlett CA, Gavriel N, McGonigle T, Majimbi M, Gopalasingam G, Rodger J, Fitzgerald M. Comparing modes of delivery of a combination of ion channel inhibitors for limiting secondary degeneration following partial optic nerve transection. Sci Rep 2019; 9:15297. [PMID: 31653948 PMCID: PMC6814709 DOI: 10.1038/s41598-019-51886-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/07/2019] [Indexed: 11/28/2022] Open
Abstract
Injury to the central nervous system is exacerbated by secondary degeneration. Previous research has shown that a combination of orally and locally administered ion channel inhibitors following partial optic nerve injury protects the myelin sheath and preserves function in the ventral optic nerve, vulnerable to secondary degeneration. However, local administration is often not clinically appropriate. This study aimed to compare the efficacy of systemic and local delivery of the ion channel inhibitor combination of lomerizine, brilliant blue G (BBG) and YM872, which inhibits voltage-gated calcium channels, P2X7 receptors and Ca2+ permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors respectively. Following a partial optic nerve transection, adult female PVG rats were treated with BBG and YM872 delivered via osmotic mini pump directly to the injury site, or via intraperitoneal injection, both alongside oral administration of lomerizine. Myelin structure was preserved with both delivery modes of the ion channel inhibitor combination. However, there was no effect of treatment on inflammation, either peripherally or at the injury site, or on the density of oligodendroglial cells. Taken together, the data indicate that even at lower concentrations, the combinatorial treatment may be preserving myelin structure, and that systemic and local delivery are comparable at improving outcomes following neurotrauma.
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Affiliation(s)
- Lillian M Toomey
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, 35 Stirling Hwy, Perth, 6009, Western Australia, Australia
- Curtin Health Innovation Research Institute, Curtin University, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia
- Perron Institute for Neurological and Translational Science, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia
| | - Carole A Bartlett
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, 35 Stirling Hwy, Perth, 6009, Western Australia, Australia
| | - Nikolas Gavriel
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, 35 Stirling Hwy, Perth, 6009, Western Australia, Australia
| | - Terence McGonigle
- Curtin Health Innovation Research Institute, Curtin University, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia
| | - Maimuna Majimbi
- Curtin Health Innovation Research Institute, Curtin University, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia
| | - Gopana Gopalasingam
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, 35 Stirling Hwy, Perth, 6009, Western Australia, Australia
| | - Jennifer Rodger
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, 35 Stirling Hwy, Perth, 6009, Western Australia, Australia
- Perron Institute for Neurological and Translational Science, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia
| | - Melinda Fitzgerald
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, 35 Stirling Hwy, Perth, 6009, Western Australia, Australia.
- Curtin Health Innovation Research Institute, Curtin University, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia.
- Perron Institute for Neurological and Translational Science, Sarich Neuroscience Research Institute Building, 8 Verdun St, Nedlands, 6009, Western Australia, Australia.
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15
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Zhang J, Yang X, Zhou Y, Fox H, Xiong H. Direct contacts of microglia on myelin sheath and Ranvier's node in the corpus callosum in rats. J Biomed Res 2019; 33:192-200. [PMID: 30403198 PMCID: PMC6551421 DOI: 10.7555/jbr.32.20180019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Over the recent years, it has been found that microglia pseudopodia contact synapses, detect sick ones and prune them, even in adult animals. Myelinated nerves also carry out plasticity in which microglia remove myelin debris by phagocytosis. However, it remains unknown whether microglia explore structures on nerve fibers, such as Ranvier's node (RN) or myelin sheath, before they become debris. By double or triple staining RNs or myelin sheathes and microglia in healthy rat corpus callosum, this study unveiled direct contacts of microglia pseudopodia with RNs and with para- and inter-nodal myelin sheathes, which was then verified by electron microscopic observations. Our data indicated that microglia also explore unmyelinated nerve fibers. Furthermore, we used the animals with matured white matter; therefore, microglia may be actively involved in plasticity of matured white matter tracts as it does for synapse pruning, instead of only passively phagocytize myelin debris.
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Affiliation(s)
- Jingdong Zhang
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Xinglong Yang
- Department of Clinical and Scientific Training, Affiliated Hospital to Academy of Military Medicine Sciences, Beijing 100071, China
| | - You Zhou
- Center for Biotechnology, University of Nebraska at Lincoln, School of Veterinary Medicine and Biomedical Sciences, Lincoln, NE 68588, USA
| | - Howard Fox
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Huangui Xiong
- Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198, USA
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16
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Anderson HE, Weir RFF. On the development of optical peripheral nerve interfaces. Neural Regen Res 2019; 14:425-436. [PMID: 30539808 PMCID: PMC6334609 DOI: 10.4103/1673-5374.245461] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 09/19/2018] [Indexed: 11/04/2022] Open
Abstract
Limb loss and spinal cord injury are two debilitating conditions that continue to grow in prevalence. Prosthetic limbs and limb reanimation present two ways of providing affected individuals with means to interact in the world. These techniques are both dependent on a robust interface with the peripheral nerve. Current methods for interfacing with the peripheral nerve tend to suffer from low specificity, high latency and insufficient robustness for a chronic implant. An optical peripheral nerve interface may solve some of these problems by decreasing invasiveness and providing single axon specificity. In order to implement such an interface three elements are required: (1) a transducer capable of translating light into a neural stimulus or translating neural activity into changes in fluorescence, (2) a means for delivering said transducer and (3) a microscope for providing the stimulus light and detecting the fluorescence change. There are continued improvements in both genetically encoded calcium and voltage indicators as well as new optogenetic actuators for stimulation. Similarly, improvements in specificity of viral vectors continue to improve expression in the axons of the peripheral nerve. Our work has recently shown that it is possible to virally transduce axons of the peripheral nerve for recording from small fibers. The improvements of these components make an optical peripheral nerve interface a rapidly approaching alternative to current methods.
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Affiliation(s)
- Hans E. Anderson
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
| | - Richard F. ff. Weir
- Department of Bioengineering, University of Colorado Denver | Anschutz Medical Campus, Aurora, CO, USA
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17
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Physiology of Myelinated Nerve Conduction and Pathophysiology of Demyelination. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:85-106. [DOI: 10.1007/978-981-32-9636-7_7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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18
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Comparison of ion channel inhibitor combinations for limiting secondary degeneration following partial optic nerve transection. Exp Brain Res 2018; 237:161-171. [DOI: 10.1007/s00221-018-5414-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 10/21/2018] [Indexed: 11/25/2022]
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19
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Zatkova M, Bacova Z, Puerta F, Lestanova Z, Alanazi M, Kiss A, Reichova A, Castejon AM, Ostatnikova D, Bakos J. Projection length stimulated by oxytocin is modulated by the inhibition of calcium signaling in U-87MG cells. J Neural Transm (Vienna) 2018; 125:1847-1856. [DOI: 10.1007/s00702-018-1933-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 09/21/2018] [Indexed: 12/12/2022]
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20
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Lassuthova P, Rebelo AP, Ravenscroft G, Lamont PJ, Davis MR, Manganelli F, Feely SM, Bacon C, Brožková DŠ, Haberlova J, Mazanec R, Tao F, Saghira C, Abreu L, Courel S, Powell E, Buglo E, Bis DM, Baxter MF, Ong RW, Marns L, Lee YC, Bai Y, Isom DG, Barro-Soria R, Chung KW, Scherer SS, Larsson HP, Laing NG, Choi BO, Seeman P, Shy ME, Santoro L, Zuchner S. Mutations in ATP1A1 Cause Dominant Charcot-Marie-Tooth Type 2. Am J Hum Genet 2018. [PMID: 29499166 DOI: 10.1016/j.ajhg.2018.01.023.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022] Open
Abstract
Although mutations in more than 90 genes are known to cause CMT, the underlying genetic cause of CMT remains unknown in more than 50% of affected individuals. The discovery of additional genes that harbor CMT2-causing mutations increasingly depends on sharing sequence data on a global level. In this way-by combining data from seven countries on four continents-we were able to define mutations in ATP1A1, which encodes the alpha1 subunit of the Na+,K+-ATPase, as a cause of autosomal-dominant CMT2. Seven missense changes were identified that segregated within individual pedigrees: c.143T>G (p.Leu48Arg), c.1775T>C (p.Ile592Thr), c.1789G>A (p.Ala597Thr), c.1801_1802delinsTT (p.Asp601Phe), c.1798C>G (p.Pro600Ala), c.1798C>A (p.Pro600Thr), and c.2432A>C (p.Asp811Ala). Immunostaining peripheral nerve axons localized ATP1A1 to the axolemma of myelinated sensory and motor axons and to Schmidt-Lanterman incisures of myelin sheaths. Two-electrode voltage clamp measurements on Xenopus oocytes demonstrated significant reduction in Na+ current activity in some, but not all, ouabain-insensitive ATP1A1 mutants, suggesting a loss-of-function defect of the Na+,K+ pump. Five mutants fall into a remarkably narrow motif within the helical linker region that couples the nucleotide-binding and phosphorylation domains. These findings identify a CMT pathway and a potential target for therapy development in degenerative diseases of peripheral nerve axons.
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Affiliation(s)
- Petra Lassuthova
- DNA Laboratory, Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague 150 06, Czech Republic
| | - Adriana P Rebelo
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Gianina Ravenscroft
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia
| | | | - Mark R Davis
- Neurogenetics Unit, Department of Diagnostic Genomics, PathWest Laboratory Medicine, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomathology, Federico II University, Naples 80131, Italy
| | - Shawna M Feely
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Chelsea Bacon
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Dana Šafka Brožková
- DNA Laboratory, Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague 150 06, Czech Republic
| | - Jana Haberlova
- Department of Pediatric Neurology, 2(nd) Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague 150 06, Czech Republic
| | - Radim Mazanec
- Department of Neurology, 2(nd) Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague 150 06, Czech Republic
| | - Feifei Tao
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Cima Saghira
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Lisa Abreu
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Steve Courel
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Eric Powell
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA; The Genesis Project foundation, Miami, FL 33136, USA
| | - Elena Buglo
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Dana M Bis
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Megan F Baxter
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia
| | - Royston W Ong
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia
| | - Lorna Marns
- Neurogenetics Unit, Department of Diagnostic Genomics, PathWest Laboratory Medicine, QEII Medical Centre, Nedlands, WA 6009, Australia
| | - Yi-Chung Lee
- Department of Neurology, Taipei Veterans General Hospital, Taipei, Taiwan, Department of Neurology, National Yang-Ming University School of Medicine, 10466 Taipei, Taiwan
| | - Yunhong Bai
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Daniel G Isom
- Department of Pharmacology, Sylvester Comprehensive Cancer Center, and Center for Computational Sciences, University of Miami, Miami, FL 33136, USA
| | - René Barro-Soria
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Ki W Chung
- Department of Biological Science, Kongju National University, Gongju 32588, Korea
| | - Steven S Scherer
- Department of Neurology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Nigel G Laing
- Centre for Medical Research, University of Western Australia and Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul 06351, Korea
| | - Pavel Seeman
- DNA Laboratory, Department of Pediatric Neurology, 2nd Faculty of Medicine, Charles University in Prague and University Hospital Motol, Prague 150 06, Czech Republic
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Lucio Santoro
- Department of Neurosciences, Reproductive Sciences and Odontostomathology, Federico II University, Naples 80131, Italy
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics, John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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21
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Mutations in ATP1A1 Cause Dominant Charcot-Marie-Tooth Type 2. Am J Hum Genet 2018; 102:505-514. [PMID: 29499166 DOI: 10.1016/j.ajhg.2018.01.023] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/30/2018] [Indexed: 11/22/2022] Open
Abstract
Although mutations in more than 90 genes are known to cause CMT, the underlying genetic cause of CMT remains unknown in more than 50% of affected individuals. The discovery of additional genes that harbor CMT2-causing mutations increasingly depends on sharing sequence data on a global level. In this way-by combining data from seven countries on four continents-we were able to define mutations in ATP1A1, which encodes the alpha1 subunit of the Na+,K+-ATPase, as a cause of autosomal-dominant CMT2. Seven missense changes were identified that segregated within individual pedigrees: c.143T>G (p.Leu48Arg), c.1775T>C (p.Ile592Thr), c.1789G>A (p.Ala597Thr), c.1801_1802delinsTT (p.Asp601Phe), c.1798C>G (p.Pro600Ala), c.1798C>A (p.Pro600Thr), and c.2432A>C (p.Asp811Ala). Immunostaining peripheral nerve axons localized ATP1A1 to the axolemma of myelinated sensory and motor axons and to Schmidt-Lanterman incisures of myelin sheaths. Two-electrode voltage clamp measurements on Xenopus oocytes demonstrated significant reduction in Na+ current activity in some, but not all, ouabain-insensitive ATP1A1 mutants, suggesting a loss-of-function defect of the Na+,K+ pump. Five mutants fall into a remarkably narrow motif within the helical linker region that couples the nucleotide-binding and phosphorylation domains. These findings identify a CMT pathway and a potential target for therapy development in degenerative diseases of peripheral nerve axons.
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22
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Kaczmarek D, Jankowska E. DC-Evoked Modulation of Excitability of Myelinated Nerve Fibers and Their Terminal Branches; Differences in Sustained Effects of DC. Neuroscience 2018; 374:236-249. [DOI: 10.1016/j.neuroscience.2018.01.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 01/16/2018] [Accepted: 01/17/2018] [Indexed: 12/20/2022]
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23
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Imaging of electrical activity in small diameter fibers of the murine peripheral nerve with virally-delivered GCaMP6f. Sci Rep 2018; 8:3219. [PMID: 29459701 PMCID: PMC5818512 DOI: 10.1038/s41598-018-21528-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 02/06/2018] [Indexed: 12/24/2022] Open
Abstract
Current neural interfaces are hampered by lack of specificity and selectivity for neural interrogation. A method that might improve these interfaces is an optical peripheral nerve interface which communicates with individual axons via optogenetic reporters. To determine the feasibility of such an interface, we delivered the genetically encoded calcium indicator GCaMP6f to the mouse peripheral nerve by intramuscular injection of adenoassociated viral vector (AAV1) under the control of the CAG (chicken beta actin- cytomegalovirus hybrid promoter). Small diameter axons in the common peroneal nerve were transduced and demonstrated electrically inducible calcium transients ex vivo. Responses to single electrical stimuli were resolvable, and increasing the number of stimuli resulted in a monotonic increase in maximum fluorescence and a prolongation of calcium transient kinetics. This work demonstrates the viability of using a virally-delivered, genetically-encoded calcium indicator to read-out from peripheral nerve axons.
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24
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Chen W, Chi YN, Kang XJ, Liu QY, Zhang HL, Li ZH, Zhao ZF, Yang Y, Su L, Cai J, Liao FF, Yi M, Wan Y, Liu FY. Accumulation of Ca v3.2 T-type Calcium Channels in the Uninjured Sural Nerve Contributes to Neuropathic Pain in Rats with Spared Nerve Injury. Front Mol Neurosci 2018; 11:24. [PMID: 29472842 PMCID: PMC5809483 DOI: 10.3389/fnmol.2018.00024] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/17/2018] [Indexed: 11/13/2022] Open
Abstract
Injuries to peripheral nerve fibers induce neuropathic pain. But the involvement of adjacent uninjured fibers to pain is not fully understood. The present study aims to investigate the possible contribution of Cav3.2 T-type calcium channels in uninjured afferent nerve fibers to neuropathic pain in rats with spared nerve injury (SNI). Aβ-, Aδ- and C-fibers of the uninjured sural nerve were sensitized revealed by in vivo single-unit recording, which were accompanied by accumulation of Cav3.2 T-type calcium channel proteins shown by Western blotting. Application of mibefradil, a T-type calcium channel blocker, to sural nerve receptive fields increased mechanical thresholds of Aβ-, Aδ- and C-fibers, confirming the functional involvement of accumulated channels in the sural nerve in SNI rats. Finally, perineural application of mibefradil or TTA-P2 to the uninjured sural nerve alleviated mechanical allodynia in SNI rats. These results suggest that axonal accumulation of Cav3.2 T-type calcium channels plays an important role in the uninjured sural nerve sensitization and contributes to neuropathic pain.
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Affiliation(s)
- Wen Chen
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Ye-Nan Chi
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Anesthesiology, Dongfang Hospital, Beijing University of Chinese Medicine, Beijing, China
| | - Xue-Jing Kang
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Qing-Ying Liu
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Hao-Lin Zhang
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Zhi-Hua Li
- Department of Human Anatomy, School of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Zi-Fang Zhao
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Yin Yang
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Li Su
- Neuroscience Research Institute, Peking University, Beijing, China.,Center of Medical and Health Analysis, Peking University, Beijing, China
| | - Jie Cai
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Fei-Fei Liao
- Neuroscience Research Institute, Peking University, Beijing, China
| | - Ming Yi
- Neuroscience Research Institute, Peking University, Beijing, China
| | - You Wan
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, China.,Key Laboratory for Neuroscience, Ministry of Education/National Health and Family Planning Commission, Peking University, Beijing, China
| | - Feng-Yu Liu
- Neuroscience Research Institute, Peking University, Beijing, China.,Department of Neurobiology, School of Basic Medical Sciences, Peking University, Beijing, China
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25
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O'Hare Doig RL, Chiha W, Giacci MK, Yates NJ, Bartlett CA, Smith NM, Hodgetts SI, Harvey AR, Fitzgerald M. Specific ion channels contribute to key elements of pathology during secondary degeneration following neurotrauma. BMC Neurosci 2017; 18:62. [PMID: 28806920 PMCID: PMC5557315 DOI: 10.1186/s12868-017-0380-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 08/05/2017] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Following partial injury to the central nervous system, cells beyond the initial injury site undergo secondary degeneration, exacerbating loss of neurons, compact myelin and function. Changes in Ca2+ flux are associated with metabolic and structural changes, but it is not yet clear how flux through specific ion channels contributes to the various pathologies. Here, partial optic nerve transection in adult female rats was used to model secondary degeneration. Treatment with combinations of three ion channel inhibitors was used as a tool to investigate which elements of oxidative and structural damage related to long term functional outcomes. The inhibitors employed were the voltage gated Ca2+ channel inhibitor Lomerizine (Lom), the Ca2+ permeable AMPA receptor inhibitor YM872 and the P2X7 receptor inhibitor oxATP. RESULTS Following partial optic nerve transection, hyper-phosphorylation of Tau and acetylated tubulin immunoreactivity were increased, and Nogo-A immunoreactivity was decreased, indicating that axonal changes occurred acutely. All combinations of ion channel inhibitors reduced hyper-phosphorylation of Tau and increased Nogo-A immunoreactivity at day 3 after injury. However, only Lom/oxATP or all three inhibitors in combination significantly reduced acetylated tubulin immunoreactivity. Most combinations of ion channel inhibitors were effective in restoring the lengths of the paranode and the paranodal gap, indicative of the length of the node of Ranvier, following injury. However, only all three inhibitors in combination restored to normal Ankyrin G length at the node of Ranvier. Similarly, HNE immunoreactivity and loss of oligodendrocyte precursor cells were only limited by treatment with all three ion channel inhibitors in combination. CONCLUSIONS Data indicate that inhibiting any of a range of ion channels preserves certain elements of axon and node structure and limits some oxidative damage following injury, whereas ionic flux through all three channels must be inhibited to prevent lipid peroxidation and preserve Ankyrin G distribution and OPCs.
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Affiliation(s)
- Ryan L O'Hare Doig
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.,Experimental and Regenerative Neurosciences, School of Human Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Wissam Chiha
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.,Experimental and Regenerative Neurosciences, School of Human Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Marcus K Giacci
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Nathanael J Yates
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Carole A Bartlett
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Nicole M Smith
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.,Experimental and Regenerative Neurosciences, School of Chemistry and Biochemistry, The University of Western Australia, Crawley, WA, 6009, Australia
| | - Stuart I Hodgetts
- Experimental and Regenerative Neurosciences, School of Human Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.,Perron Institute for Neurological and Translational Science, Verdun St, Nedlands, WA, 6009, Australia
| | - Alan R Harvey
- Experimental and Regenerative Neurosciences, School of Human Sciences, The University of Western Australia, Crawley, WA, 6009, Australia.,Perron Institute for Neurological and Translational Science, Verdun St, Nedlands, WA, 6009, Australia
| | - Melinda Fitzgerald
- Experimental and Regenerative Neurosciences, School of Biological Sciences, The University of Western Australia, Crawley, WA, 6009, Australia. .,Curtin Health Innovation Research Institute, Curtin University, Perth, WA, Australia. .,Perron Institute for Neurological and Translational Science, Verdun St, Nedlands, WA, 6009, Australia.
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26
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Fontaine AK, Gibson EA, Caldwell JH, Weir RF. Optical Read-out of Neural Activity in Mammalian Peripheral Axons: Calcium Signaling at Nodes of Ranvier. Sci Rep 2017; 7:4744. [PMID: 28720792 PMCID: PMC5516017 DOI: 10.1038/s41598-017-03541-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 04/28/2017] [Indexed: 12/11/2022] Open
Abstract
Current neural interface technologies have serious limitations for advanced prosthetic and therapeutic applications due primarily to their lack of specificity in neural communication. An optogenetic approach has the potential to provide single cell/axon resolution in a minimally invasive manner by optical interrogation of light-sensitive reporters and actuators. Given the aim of reading neural activity in the peripheral nervous system, this work has investigated an activity-dependent signaling mechanism in the peripheral nerve. We demonstrate action potential evoked calcium signals in mammalian tibial nerve axons using an in vitro mouse model with a dextran-conjugated fluorescent calcium indicator. Spatial and temporal dynamics of the signal are presented, including characterization of frequency-modulated amplitude. Pharmacological experiments implicate T-type CaV channels and sodium-calcium exchanger (NCX) as predominant mechanisms of calcium influx. This work shows the potential of using calcium-associated optical signals for neural activity read-out in peripheral nerve axons.
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Affiliation(s)
- Arjun K Fontaine
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA.
| | - Emily A Gibson
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA
| | - John H Caldwell
- Department of Cell and Developmental Biology, University of Colorado - Anschutz Medical Campus, Colorado, USA
| | - Richard F Weir
- Department of Bioengineering, University of Colorado - Anschutz Medical Campus, Colorado, USA
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27
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Zatkova M, Reichova A, Bacova Z, Strbak V, Kiss A, Bakos J. Neurite Outgrowth Stimulated by Oxytocin Is Modulated by Inhibition of the Calcium Voltage-Gated Channels. Cell Mol Neurobiol 2017; 38:371-378. [DOI: 10.1007/s10571-017-0503-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/06/2017] [Indexed: 11/29/2022]
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28
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Nimodipine but Not Nifedipine Promotes Expression of Fatty Acid 2-Hydroxylase in a Surgical Stress Model Based on Neuro2a Cells. Int J Mol Sci 2017; 18:ijms18050964. [PMID: 28467360 PMCID: PMC5454877 DOI: 10.3390/ijms18050964] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 04/20/2017] [Accepted: 04/26/2017] [Indexed: 11/18/2022] Open
Abstract
Nimodipine is well characterized for the management of aneurysmal subarachnoid hemorrhage and has been shown to promote a better outcome and less delayed ischemic neurological deficits. Animal and clinical trials show neuroprotective efficacy following nerve injuries. We showed a neuroprotective effect on Neuro2a cells. Subsequent microarray analysis revealed—among others—fatty acid 2-hydroxylase (FA2H) upregulated by nimodipine in vitro, which is a component of myelin synthesis. Differentiated Neuro2a cells were analyzed for nimodipine-mediated survival considering stress treatment in comparison to nifedipine-treatment. Cell survival was determined by measurement of LDH activity in the culture medium. Nimodipine decreased surgery-like stress-induced cell death of differentiated Neuro2a cells. Neuro2a cell culture was analyzed for changes in FA2H expression induced by nimodipine or nifedipine in surgery-like stress conditions. We analyzed expression levels of FA2H mRNA and protein by qPCR using fa2h specific primers or a FA2H-specific antibody in nimodipine or nifedipine non- and pre-treated Neuro2a cell culture, respectively. Nimodipine but not nifedipine increases FA2H protein levels and also significantly increases mRNA levels of FA2H in both undifferentiated and differentiated Neuro2a cells. Our findings indicate that higher expression of FA2H induced by nimodipine may cause higher survival of Neuro2a cells stressed with surgery-like stressors.
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29
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Abstract
Axonal degeneration is a pivotal feature of many neurodegenerative conditions and substantially accounts for neurological morbidity. A widely used experimental model to study the mechanisms of axonal degeneration is Wallerian degeneration (WD), which occurs after acute axonal injury. In the peripheral nervous system (PNS), WD is characterized by swift dismantling and clearance of injured axons with their myelin sheaths. This is a prerequisite for successful axonal regeneration. In the central nervous system (CNS), WD is much slower, which significantly contributes to failed axonal regeneration. Although it is well-documented that Schwann cells (SCs) have a critical role in the regenerative potential of the PNS, to date we have only scarce knowledge as to how SCs ‘sense’ axonal injury and immediately respond to it. In this regard, it remains unknown as to whether SCs play the role of a passive bystander or an active director during the execution of the highly orchestrated disintegration program of axons. Older reports, together with more recent studies, suggest that SCs mount dynamic injury responses minutes after axonal injury, long before axonal breakdown occurs. The swift SC response to axonal injury could play either a pro-degenerative role, or alternatively a supportive role, to the integrity of distressed axons that have not yet committed to degenerate. Indeed, supporting the latter concept, recent findings in a chronic PNS neurodegeneration model indicate that deactivation of a key molecule promoting SC injury responses exacerbates axonal loss. If this holds true in a broader spectrum of conditions, it may provide the grounds for the development of new glia-centric therapeutic approaches to counteract axonal loss.
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Affiliation(s)
- Keit Men Wong
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Elisabetta Babetto
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.,Department of Pharmacology and Toxicology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Bogdan Beirowski
- Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA.,Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
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30
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Tomlinson SE, Tan SV, Burke D, Labrum RW, Haworth A, Gibbons VS, Sweeney MG, Griggs RC, Kullmann DM, Bostock H, Hanna MG. In vivo impact of presynaptic calcium channel dysfunction on motor axons in episodic ataxia type 2. Brain 2016; 139:380-91. [PMID: 26912519 PMCID: PMC4795516 DOI: 10.1093/brain/awv380] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 10/22/2015] [Accepted: 10/26/2015] [Indexed: 11/13/2022] Open
Abstract
Ion channel dysfunction causes a range of neurological disorders by altering transmembrane ion fluxes, neuronal or muscle excitability, and neurotransmitter release. Genetic neuronal channelopathies affecting peripheral axons provide a unique opportunity to examine the impact of dysfunction of a single channel subtype in detail in vivo. Episodic ataxia type 2 is caused by mutations in CACNA1A, which encodes the pore-forming subunit of the neuronal voltage-gated calcium channel Cav2.1. In peripheral motor axons, this channel is highly expressed at the presynaptic neuromuscular junction where it contributes to action potential-evoked neurotransmitter release, but it is not expressed mid-axon or thought to contribute to action potential generation. Eight patients from five families with genetically confirmed episodic ataxia type 2 underwent neurophysiological assessment to determine whether axonal excitability was normal and, if not, whether changes could be explained by Cav2.1 dysfunction. New mutations in the CACNA1A gene were identified in two families. Nerve conduction studies were normal, but increased jitter in single-fibre EMG studies indicated unstable neuromuscular transmission in two patients. Excitability properties of median motor axons were compared with those in 30 age-matched healthy control subjects. All patients had similar excitability abnormalities, including a high electrical threshold and increased responses to hyperpolarizing (P < 0.00007) and depolarizing currents (P < 0.001) in threshold electrotonus. In the recovery cycle, refractoriness (P < 0.0002) and superexcitability (P < 0.006) were increased. Cav2.1 dysfunction in episodic ataxia type 2 thus has unexpected effects on axon excitability, which may reflect an indirect effect of abnormal calcium current fluxes during development.
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Affiliation(s)
- Susan E Tomlinson
- 1 Sydney Medical School, University of Sydney, Australia 2 Department of Neurology, St Vincent's Hospital, Sydney, Australia
| | - S Veronica Tan
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK
| | - David Burke
- 1 Sydney Medical School, University of Sydney, Australia 4 Department of Neurology, Royal Prince Alfred Hospital, Sydney, Australia
| | - Robyn W Labrum
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | - Andrea Haworth
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | | | - Mary G Sweeney
- 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | | | - Dimitri M Kullmann
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
| | - Hugh Bostock
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK
| | - Michael G Hanna
- 3 Institute of Neurology, University College London and MRC Centre for Neuromuscular Disease, Queen Square, UK 5 Neurogenetics Unit, National Hospital for Neurology, Queen Square, UK
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31
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Schwarz JR. Ca(2+) channels in the node of Ranvier: new insights into modulation of nodal excitability. J Physiol 2016; 594:3-4. [PMID: 26724478 DOI: 10.1113/jp271566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 10/09/2015] [Indexed: 11/08/2022] Open
Affiliation(s)
- Jürgen R Schwarz
- Institute for Molecular Neurogenetics, Center for Molecular Neurobiology (ZMNH), University of Hamburg, D-20251, Hamburg, Germany
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