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Modulation of C-nociceptive Activities by Inputs from Myelinated Fibers. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 904:33-40. [PMID: 26900061 DOI: 10.1007/978-94-017-7537-3_3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
To understand the mechanisms of neuropathic pain caused by demyelination, a rapid-onset, completed but reversible demyelination of peripheral A-fibers and neuropathic pain behaviors in adult rats by single injection of cobra venom into the sciatic nerve, was created. Microfilament recording revealed that cobra venom selectively blocked A-fibers, but not C-fibers. Selective blockade of A-fibers may result from A-fiber demyelination at the site of venom injection as demonstrated by microscope examination. Neuropathic pain behaviors including inflammatory response appeared almost immediately after venom injection and lasted about 3 weeks. Electrophysiological studies indicated that venom injection induced loss of conduction in A-fibers, increased sensitivity of C-polymodal nociceptors to innocuous stimuli, and triggered spontaneous activity from peripheral and central terminals of C-fiber nociceptors. Neurogenic inflammatory responses were also observed in the affected skin via Evans blue extravasation experiments. Both antidromic C-fiber spontaneous activity and neurogenic inflammation were substantially decreased by continuous A-fiber threshold electric stimuli applied proximally to the venom injection site. The data suggest that normal activity of peripheral A-fibers may produce inhibitory modulation of C-polymodal nociceptors. Removal of inhibition to C-fiber polymodal nociceptors following demyelination of A-fibers may result in pain and neurogenic inflammation in the affected receptive field.
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Maddala R, Walters M, Brophy PJ, Bennett V, Rao PV. Ankyrin-B directs membrane tethering of periaxin and is required for maintenance of lens fiber cell hexagonal shape and mechanics. Am J Physiol Cell Physiol 2015; 310:C115-26. [PMID: 26538089 DOI: 10.1152/ajpcell.00111.2015] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 10/31/2015] [Indexed: 12/22/2022]
Abstract
Periaxin (Prx), a PDZ domain protein expressed preferentially in myelinating Schwann cells and lens fibers, plays a key role in membrane scaffolding and cytoarchitecture. Little is known, however, about how Prx is anchored to the plasma membrane. Here we report that ankyrin-B (AnkB), a well-characterized adaptor protein involved in linking the spectrin-actin cytoskeleton to integral membrane proteins, is required for membrane association of Prx in lens fibers and colocalizes with Prx in hexagonal fiber cells. Under AnkB haploinsufficiency, Prx accumulates in the soluble fraction with a concomitant loss from the membrane-enriched fraction of mouse lenses. Moreover, AnkB haploinsufficiency induced age-dependent disruptions in fiber cell hexagonal geometry and radial alignment and decreased compressive stiffness in mouse lenses parallel to the changes observed in Prx null mouse lens. Both AnkB- and Prx-deficient mice exhibit disruptions in membrane organization of the spectrin-actin network and the dystrophin-glycoprotein complex in lens fiber cells. Taken together, these observations reveal that AnkB is required for Prx membrane anchoring and for maintenance of lens fiber cell hexagonal geometry, membrane skeleton organization, and biomechanics.
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Affiliation(s)
- Rupalatha Maddala
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina
| | - Mark Walters
- Department of Mechanical Engineering and Materials Science, Pratt School of Engineering, Duke University, Durham, North Carolina
| | - Peter J Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, United Kingdom
| | - Vann Bennett
- Howard Hughes Medical Institute, Chevy Chase, Maryland; Department of Biochemistry, Duke University School of Medicine, Durham, North Carolina; and
| | - Ponugoti V Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina; Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, North Carolina
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Brennan KM, Bai Y, Pisciotta C, Wang S, Feely SME, Hoegger M, Gutmann L, Moore SA, Gonzalez M, Sherman DL, Brophy PJ, Züchner S, Shy ME. Absence of Dystrophin Related Protein-2 disrupts Cajal bands in a patient with Charcot-Marie-Tooth disease. Neuromuscul Disord 2015; 25:786-93. [PMID: 26227883 PMCID: PMC4920059 DOI: 10.1016/j.nmd.2015.07.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 06/28/2015] [Accepted: 07/01/2015] [Indexed: 12/12/2022]
Abstract
Using exome sequencing in an individual with Charcot-Marie-Tooth disease (CMT) we have identified a mutation in the X-linked dystrophin-related protein 2 (DRP2) gene. A 60-year-old gentleman presented to our clinic and underwent clinical, electrophysiological and skin biopsy studies. The patient had clinical features of a length dependent sensorimotor neuropathy with an age of onset of 50 years. Neurophysiology revealed prolonged latencies with intermediate conduction velocities but no conduction block or temporal dispersion. A panel of 23 disease causing genes was sequenced and ultimately was uninformative. Whole exome sequencing revealed a stop mutation in DRP2, c.805C>T (Q269*). DRP2 interacts with periaxin and dystroglycan to form the periaxin-DRP2-dystroglycan complex which plays a role in the maintenance of the well-characterized Cajal bands of myelinating Schwann cells. Skin biopsies from our patient revealed a lack of DRP2 in myelinated dermal nerves by immunofluorescence. Furthermore electron microscopy failed to identify Cajal bands in the patient's dermal myelinated axons in keeping with ultrastructural pathology seen in the Drp2 knockout mouse. Both the electrophysiologic and dermal nerve twig pathology support the interpretation that this patient's DRP2 mutation causes characteristic morphological abnormalities recapitulating the Drp2 knockout model and potentially represents a novel genetic cause of CMT.
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Affiliation(s)
- Kathryn M Brennan
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA.
| | - Yunhong Bai
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Chiara Pisciotta
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Suola Wang
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Shawna M E Feely
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Mark Hoegger
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Laurie Gutmann
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Steven A Moore
- Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Michael Gonzalez
- Department of Human Genetics and Hussmann Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Diane L Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Peter J Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Stephan Züchner
- Department of Human Genetics and Hussmann Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL 33136, USA
| | - Michael E Shy
- Department of Neurology, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA
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Abstract
Myelinated nerve fibers are essential for the rapid propagation of action potentials by saltatory conduction. They form as the result of reciprocal interactions between axons and Schwann cells. Extrinsic signals from the axon, and the extracellular matrix, drive Schwann cells to adopt a myelinating fate, whereas myelination reorganizes the axon for its role in conduction and is essential for its integrity. Here, we review our current understanding of the development, molecular organization, and function of myelinating Schwann cells. Recent findings into the extrinsic signals that drive Schwann cell myelination, their cognate receptors, and the downstream intracellular signaling pathways they activate will be described. Together, these studies provide important new insights into how these pathways converge to activate the transcriptional cascade of myelination and remodel the actin cytoskeleton that is critical for morphogenesis of the myelin sheath.
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Affiliation(s)
- James L Salzer
- Department of Neuroscience and Physiology, New York University Neuroscience Institute, New York University School of Medicine, New York, New York 10016
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Notch signaling activation is critical to the development of neuropathic pain. BMC Anesthesiol 2015; 15:41. [PMID: 25821407 PMCID: PMC4377217 DOI: 10.1186/s12871-015-0021-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 03/10/2015] [Indexed: 02/01/2023] Open
Abstract
Background Nerve injury-induced neuropathic pain is a major health problem worldwide. Notch signaling is a highly conserved pathway in evolution, which has an important role in synaptic plasticity and inflammation in central nervous system. The present study was designed to investigate the potential role of notch signaling in the development of neuropathic pain. Methods The neuropathic pain was induced by spared nerve injury (SNI) in rats. The activation of notch signaling in the lumbar spinal dorsal horn was measured. DAPT, an inhibitor of notch signaling, was intrathecally (i.t.) administered before SNI or after appearance of pain sensitivity. Moreover, Jagged-1 (JAG-1) peptide, a ligand of notch signaling, was i.t. administered to normal rats. The mechanical allodynia was assessed by von Frey test. Results Here, we found that DAPT administered 0.5 h before SNI operation could significantly prevent the decrease of mechanical paw withdrawal threshold (PWT) for more than 4 weeks (P < 0.05 vs. SNI group). DAPT administered after appearance of pain sensitivity could also significantly reverse the decrease of mechanical PWT in a dose-dependent manner (P < 0.05). In addition, administration of Jagged-1 (JAG-1) peptide significantly decreased the mechanical PWT of normal rats in a dose-dependent manner (P < 0.05). Conclusions Therefore, notch signaling activation might contribute to the development of neuropathic pain. This study might provide a new therapeutic target for neuropathic pain.
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Nerve demyelination increases metabotropic glutamate receptor subtype 5 expression in peripheral painful mononeuropathy. Int J Mol Sci 2015; 16:4642-65. [PMID: 25739080 PMCID: PMC4394440 DOI: 10.3390/ijms16034642] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 02/12/2015] [Accepted: 02/13/2015] [Indexed: 01/24/2023] Open
Abstract
Wallerian degeneration or nerve demyelination, arising from spinal nerve compression, is thought to bring on chronic neuropathic pain. The widely distributed metabotropic glutamate receptor subtype 5 (mGluR5) is involved in modulating nociceptive transmission. The purpose of this study was to investigate the potential effects of mGluR5 on peripheral hypersensitivities after chronic constriction injury (CCI). Sprague-Dawley rats were operated on with four loose ligatures around the sciatic nerve to induce thermal hyperalgesia and mechanical allodynia. Primary afferents in dermis after CCI exhibited progressive decreases, defined as partial cutaneous denervation; importantly, mGluR5 expressions in primary afferents were statistically increased. CCI-induced neuropathic pain behaviors through the intraplantar injections of 2-methyl-6-(phenylethynyl)-pyridine (MPEP), a selective mGluR5 antagonist, were dose-dependently attenuated. Furthermore, the most increased mGluR5 expressions in primary afferents surrounded by reactive Schwann cells were observed at the distal CCI stumps of sciatic nerves. In conclusion, these results suggest that nerve demyelination results in the increases of mGluR5 expression in injured primary afferents after CCI; and further suggest that mGluR5 represents a main therapeutic target in developing pharmacological strategies to prevent peripheral hypersensitivities.
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Yang Y, Shi Y. Retracted Article: Spectrin-like domain 2 of DRP2 serves as a novel binding region for the NLS2 and 3 sub-domains of L-periaxin. RSC Adv 2015. [DOI: 10.1039/c5ra12703c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The NLS1 domain of L-periaxin involved in nucleo-cytoplasmic shuttling, NLS2 and 3 participated in interaction with spectrin-like domain 2 of DRP2. The binding model of DRP2 and L-periaxin is crucial for understanding the role of L-periaxin in PNS.
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Affiliation(s)
- Yan Yang
- Key Laboratory of Chemical Biology and Molecular Engineering of the Ministry of Education
- Institute of Biotechnology
- Shanxi University
- Taiyuan 030006
- China
| | - YaWei Shi
- Key Laboratory of Chemical Biology and Molecular Engineering of the Ministry of Education
- Institute of Biotechnology
- Shanxi University
- Taiyuan 030006
- China
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Choi YJ, Hyun YS, Nam SH, Koo H, Hong YB, Chung KW, Choi BO. Novel Compound Heterozygous Nonsense PRX Mutations in a Korean Dejerine-Sottas Neuropathy Family. J Clin Neurol 2014; 11:92-6. [PMID: 25628743 PMCID: PMC4302186 DOI: 10.3988/jcn.2015.11.1.92] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 09/09/2013] [Accepted: 09/13/2013] [Indexed: 12/24/2022] Open
Abstract
Background Mutations in the gene encoding periaxin (PRX) are known to cause autosomal recessive Dejerine-Sottas neuropathy (DSN) or Charcot-Marie-Tooth disease type 4F. However, there have been no reports describing Korean patients with these mutations. Case Report We examined a Korean DSN patient with an early-onset, slowly progressive, demyelinating neuropathy with prominent sensory involvement. Whole-exome sequencing and subsequent capillary sequencing revealed novel compound heterozygous nonsense mutations (p.R392X and p.R679X) in PRX. One mutation was transmitted from each of the patient's parents. No unaffected family member had both mutations, and the mutations were not found in healthy controls. Conclusions We believe that these novel compound heterozygous nonsense mutations are the underlying cause of DSN. The clinical, electrophysiologic, and pathologic phenotypes in this family were similar to those described previously for patients with PRX mutations. We have identified the first PRX mutation in a Korean patient with DSN.
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Affiliation(s)
- Ye Ji Choi
- Department of Neurology, Ewha Womans University School of Medicine, Seoul, Korea
| | - Young Se Hyun
- Department of Biological Science, Kongju National University, Gongju, Korea
| | - Soo Hyun Nam
- Department of Biological Science, Kongju National University, Gongju, Korea
| | - Heasoo Koo
- Department of Pathology, Ewha Womans University School of Medicine, Seoul, Korea
| | - Young Bin Hong
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Ki Wha Chung
- Department of Biological Science, Kongju National University, Gongju, Korea
| | - Byung-Ok Choi
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
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Beutler AS, Kulkarni AA, Kanwar R, Klein CJ, Therneau TM, Qin R, Banck MS, Boora GK, Ruddy KJ, Wu Y, Smalley RL, Cunningham JM, Le-Lindqwister NA, Beyerlein P, Schroth GP, Windebank AJ, Züchner S, Loprinzi CL. Sequencing of Charcot-Marie-Tooth disease genes in a toxic polyneuropathy. Ann Neurol 2014; 76:727-37. [PMID: 25164601 DOI: 10.1002/ana.24265] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 08/14/2014] [Accepted: 08/22/2014] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Mutations in Charcot-Marie-Tooth disease (CMT) genes are the cause of rare familial forms of polyneuropathy. Whether allelic variability in CMT genes is also associated with common forms of polyneuropathy-considered "acquired" in medical parlance-is unknown. Chemotherapy-induced peripheral neuropathy (CIPN) occurs commonly in cancer patients and is individually unpredictable. We used CIPN as a clinical model to investigate the association of non-CMT polyneuropathy with CMT genes. METHODS A total of 269 neurologically asymptomatic cancer patients were enrolled in the clinical trial Alliance N08C1 to receive the neurotoxic drug paclitaxel, while undergoing prospective assessments for polyneuropathy. Forty-nine CMT genes were analyzed by targeted massively parallel sequencing of genomic DNA from patient blood. RESULTS A total of 119 (of 269) patients were identified from the 2 ends of the polyneuropathy phenotype distribution: patients that were most and least susceptible to paclitaxel polyneuropathy. The CMT gene PRX was found to be deleteriously mutated in patients who were susceptible to CIPN but not in controls (p = 8 × 10(-3)). Genetic variation in another CMT gene, ARHGEF10, was highly significantly associated with CIPN (p = 5 × 10(-4)). Three nonsynonymous recurrent single nucleotide variants contributed to the ARHGEF10 signal: rs9657362, rs2294039, and rs17683288. Of these, rs9657362 had the strongest effect (odds ratio = 4.8, p = 4 × 10(-4)). INTERPRETATION The results reveal an association of CMT gene allelic variability with susceptibility to CIPN. The findings raise the possibility that other acquired polyneuropathies may also be codetermined by genetic etiological factors, of which some may be related to genes already known to cause the phenotypically related Mendelian disorders of CMT.
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Affiliation(s)
- Andreas S Beutler
- Department of Oncology, Mayo Clinic, Rochester, MN; Cancer Center, Mayo Clinic, Rochester, MN
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Jerath NU, Shy ME. Hereditary motor and sensory neuropathies: Understanding molecular pathogenesis could lead to future treatment strategies. Biochim Biophys Acta Mol Basis Dis 2014; 1852:667-78. [PMID: 25108281 DOI: 10.1016/j.bbadis.2014.07.031] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/02/2014] [Accepted: 07/30/2014] [Indexed: 10/24/2022]
Abstract
Inherited peripheral neuropathies, like many other degenerative disorders, have been challenging to treat. At this point, there is little specific therapy for the inherited neuropathies other than genetic counseling as well as symptomatic treatment and rehabilitation. In the past, ascorbic acid, progesterone antagonists, and subcutaneous neurotrophin-3 (NT3) injections have demonstrated improvement in animal models of CMT 1A, the most common inherited neuropathy, but have failed to translate any effect in humans. Given the difficulty in treatment, it is important to understand the molecular pathogenesis of hereditary neuropathies in order to strategize potential future therapies. The hereditary neuropathies are in an era of molecular insight and over the past 20 years, more than 78 subtypes of Charcot Marie Tooth disease (CMT) have been identified and extensively studied to understand the biological pathways in greater detail. Next generation molecular sequencing has also improved the diagnosis as well as the understanding of CMT. A greater understanding of the molecular pathways will help pave the way to future therapeutics of CMT. This article is part of a Special Issue entitled: Neuromuscular Diseases: Pathology and Molecular Pathogenesis.
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Affiliation(s)
- Nivedita U Jerath
- University of Iowa, Carver College of Medicine, Department of Neurology, 200 Hawkins Drive, Iowa City, IA 52242, USA
| | - Michael E Shy
- University of Iowa, Carver College of Medicine, Department of Neurology, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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Han H, Kursula P. Periaxin and AHNAK nucleoprotein 2 form intertwined homodimers through domain swapping. J Biol Chem 2014; 289:14121-31. [PMID: 24675079 PMCID: PMC4022880 DOI: 10.1074/jbc.m114.554816] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 03/24/2014] [Indexed: 11/06/2022] Open
Abstract
Periaxin (PRX) is an abundant protein in the peripheral nervous system, with an important role in myelination. PRX participates in large molecular complexes, most likely through the interactions of its N-terminal PSD-95/Discs-large/ZO-1 (PDZ)-like domain. We present the crystal structures of the PDZ-like domains from PRX and its homologue AHNAK nucleoprotein 2 (AHNAK2). The unique intertwined, domain-swapped dimers provide a structural basis for the homodimerization of both proteins. The core of the homodimer is formed by a 6-stranded antiparallel β sheet, with every other strand from a different chain. The AHNAK2 PDZ domain structure contains a bound class III ligand peptide. The binding pocket is preformed, and the peptide-PDZ interactions have unique aspects, including two salt bridges and weak recognition of the peptide C terminus. Tight homodimerization may be central to the scaffolding functions of PRX and AHNAK2 in molecular complexes linking the extracellular matrix to the cytoskeletal network.
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Affiliation(s)
- Huijong Han
- From the Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, 90014 Oulu, Finland, the German Electron Synchrotron (DESY), 22607 Hamburg, Germany, and
| | - Petri Kursula
- From the Faculty of Biochemistry and Molecular Medicine and Biocenter Oulu, University of Oulu, 90014 Oulu, Finland, the German Electron Synchrotron (DESY), 22607 Hamburg, Germany, and the Department of Chemistry, University of Hamburg, 22607 Hamburg, Germany
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Heller BA, Ghidinelli M, Voelkl J, Einheber S, Smith R, Grund E, Morahan G, Chandler D, Kalaydjieva L, Giancotti F, King RH, Fejes-Toth AN, Fejes-Toth G, Feltri ML, Lang F, Salzer JL. Functionally distinct PI 3-kinase pathways regulate myelination in the peripheral nervous system. J Cell Biol 2014; 204:1219-36. [PMID: 24687281 PMCID: PMC3971744 DOI: 10.1083/jcb.201307057] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Accepted: 02/18/2014] [Indexed: 02/02/2023] Open
Abstract
The PI 3-kinase (PI 3-K) signaling pathway is essential for Schwann cell myelination. Here we have characterized PI 3-K effectors activated during myelination by probing myelinating cultures and developing nerves with an antibody that recognizes phosphorylated substrates for this pathway. We identified a discrete number of phospho-proteins including the S6 ribosomal protein (S6rp), which is down-regulated at the onset of myelination, and N-myc downstream-regulated gene-1 (NDRG1), which is up-regulated strikingly with myelination. We show that type III Neuregulin1 on the axon is the primary activator of S6rp, an effector of mTORC1. In contrast, laminin-2 in the extracellular matrix (ECM), signaling through the α6β4 integrin and Sgk1 (serum and glucocorticoid-induced kinase 1), drives phosphorylation of NDRG1 in the Cajal bands of the abaxonal compartment. Unexpectedly, mice deficient in α6β4 integrin signaling or Sgk1 exhibit hypermyelination during development. These results identify functionally and spatially distinct PI 3-K pathways: an early, pro-myelinating pathway driven by axonal Neuregulin1 and a later-acting, laminin-integrin-dependent pathway that negatively regulates myelination.
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Affiliation(s)
- Bradley A. Heller
- Neuroscience Institute and Departments of Neuroscience and Physiology and Neurology, NYU Langone Medical Center, New York, NY 10016
| | - Monica Ghidinelli
- University of Buffalo School of Medicine, Hunter James Kelly Research Institute, Buffalo, NY 14214
| | - Jakob Voelkl
- Department of Physiology, University of Tübingen, 72076 Tübingen, Germany
| | - Steven Einheber
- Department of Medical Laboratory Sciences, Hunter College, City University of New York, New York, NY 10010
| | - Ryan Smith
- Neuroscience Institute and Departments of Neuroscience and Physiology and Neurology, NYU Langone Medical Center, New York, NY 10016
| | - Ethan Grund
- Neuroscience Institute and Departments of Neuroscience and Physiology and Neurology, NYU Langone Medical Center, New York, NY 10016
| | - Grant Morahan
- Western Australian Institute for Medical Research/Centre for Medical Research, The University of Western Australia, Perth 6009, Australia
| | - David Chandler
- Western Australian Institute for Medical Research/Centre for Medical Research, The University of Western Australia, Perth 6009, Australia
| | - Luba Kalaydjieva
- Western Australian Institute for Medical Research/Centre for Medical Research, The University of Western Australia, Perth 6009, Australia
| | - Filippo Giancotti
- Department of Cell Biology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065
| | - Rosalind H. King
- UCL Institute of Neurology, University College London, London NW3 2PF, England, UK
| | - Aniko Naray Fejes-Toth
- Department of Physiology and Neurobiology, Geisel School of Medicine, Dartmouth College, Lebanon, NH 03756
| | - Gerard Fejes-Toth
- Department of Physiology and Neurobiology, Geisel School of Medicine, Dartmouth College, Lebanon, NH 03756
| | - Maria Laura Feltri
- University of Buffalo School of Medicine, Hunter James Kelly Research Institute, Buffalo, NY 14214
| | - Florian Lang
- Department of Physiology, University of Tübingen, 72076 Tübingen, Germany
| | - James L. Salzer
- Neuroscience Institute and Departments of Neuroscience and Physiology and Neurology, NYU Langone Medical Center, New York, NY 10016
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Guo J, Wang L, Zhang Y, Wu J, Arpag S, Hu B, Imhof BA, Tian X, Carter BD, Suter U, Li J. Abnormal junctions and permeability of myelin in PMP22-deficient nerves. Ann Neurol 2014; 75:255-65. [PMID: 24339129 DOI: 10.1002/ana.24086] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 11/24/2013] [Accepted: 12/03/2013] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The peripheral myelin protein-22 (PMP22) gene is associated with the most common types of inherited neuropathies, including hereditary neuropathy with liability to pressure palsies (HNPP) caused by PMP22 deficiency. However, the function of PMP22 has yet to be defined. Our previous study has shown that PMP22 deficiency causes an impaired propagation of nerve action potentials in the absence of demyelination. In the present study, we tested an alternative mechanism relating to myelin permeability. METHODS Utilizing Pmp22(+) (/) (-) mice as a model of HNPP, we evaluated myelin junctions and their permeability using morphological, electrophysiological, and biochemical approaches. RESULTS We show disruption of multiple types of cell junction complexes in peripheral nerve, resulting in increased permeability of myelin and impaired action potential propagation. We further demonstrate that PMP22 interacts with immunoglobulin domain-containing proteins known to regulate tight/adherens junctions and/or transmembrane adhesions, including junctional adhesion molecule-C (JAM-C) and myelin-associated glycoprotein (MAG). Deletion of Jam-c or Mag in mice recapitulates pathology in HNPP. INTERPRETATION Our study reveals a novel mechanism by which PMP22 deficiency affects nerve conduction not through removal of myelin, but through disruption of myelin junctions.
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Affiliation(s)
- Jiasong Guo
- Department of Neurology, Center for Human Genetics Research, Vanderbilt Brain Institute, Vanderbilt University School of Medicine, Nashville, TN
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Niemann A, Huber N, Wagner KM, Somandin C, Horn M, Lebrun-Julien F, Angst B, Pereira JA, Halfter H, Welzl H, Feltri ML, Wrabetz L, Young P, Wessig C, Toyka KV, Suter U. The Gdap1 knockout mouse mechanistically links redox control to Charcot-Marie-Tooth disease. ACTA ACUST UNITED AC 2014; 137:668-82. [PMID: 24480485 PMCID: PMC3927703 DOI: 10.1093/brain/awt371] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Mutations in the mitochondrial fission factor GDAP1 are associated with severe peripheral neuropathies, but why the CNS remains unaffected is unclear. Using a Gdap1−/− mouse, Niemann et al. demonstrate that a CNS-expressed Gdap1 paralogue changes its subcellular localisation under oxidative stress conditions to also act as a mitochondrial fission factor. The ganglioside-induced differentiation-associated protein 1 (GDAP1) is a mitochondrial fission factor and mutations in GDAP1 cause Charcot–Marie–Tooth disease. We found that Gdap1 knockout mice (Gdap1−/−), mimicking genetic alterations of patients suffering from severe forms of Charcot–Marie–Tooth disease, develop an age-related, hypomyelinating peripheral neuropathy. Ablation of Gdap1 expression in Schwann cells recapitulates this phenotype. Additionally, intra-axonal mitochondria of peripheral neurons are larger in Gdap1−/− mice and mitochondrial transport is impaired in cultured sensory neurons of Gdap1−/− mice compared with controls. These changes in mitochondrial morphology and dynamics also influence mitochondrial biogenesis. We demonstrate that mitochondrial DNA biogenesis and content is increased in the peripheral nervous system but not in the central nervous system of Gdap1−/− mice compared with control littermates. In search for a molecular mechanism we turned to the paralogue of GDAP1, GDAP1L1, which is mainly expressed in the unaffected central nervous system. GDAP1L1 responds to elevated levels of oxidized glutathione by translocating from the cytosol to mitochondria, where it inserts into the mitochondrial outer membrane. This translocation is necessary to substitute for loss of GDAP1 expression. Accordingly, more GDAP1L1 was associated with mitochondria in the spinal cord of aged Gdap1−/− mice compared with controls. Our findings demonstrate that Charcot–Marie–Tooth disease caused by mutations in GDAP1 leads to mild, persistent oxidative stress in the peripheral nervous system, which can be compensated by GDAP1L1 in the unaffected central nervous system. We conclude that members of the GDAP1 family are responsive and protective against stress associated with increased levels of oxidized glutathione.
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Affiliation(s)
- Axel Niemann
- 1 Institute of Molecular Health Sciences, Cell Biology, Department of Biology, ETH Zurich, Swiss Federal Institute of Technology, Switzerland, ETH-Hönggerberg, 8093 Zürich, Switzerland
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Samara C, Poirot O, Domènech-Estévez E, Chrast R. Neuronal activity in the hub of extrasynaptic Schwann cell-axon interactions. Front Cell Neurosci 2013; 7:228. [PMID: 24324401 PMCID: PMC3839048 DOI: 10.3389/fncel.2013.00228] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 11/05/2013] [Indexed: 12/21/2022] Open
Abstract
The integrity and function of neurons depend on their continuous interactions with glial cells. In the peripheral nervous system glial functions are exerted by Schwann cells (SCs). SCs sense synaptic and extrasynaptic manifestations of action potential propagation and adapt their physiology to support neuronal activity. We review here existing literature data on extrasynaptic bidirectional axon-SC communication, focusing particularly on neuronal activity implications. To shed light on underlying mechanisms, we conduct a thorough analysis of microarray data from SC-rich mouse sciatic nerve at different developmental stages and in neuropathic models. We identify molecules that are potentially involved in SC detection of neuronal activity signals inducing subsequent glial responses. We further suggest that alterations in the activity-dependent axon-SC crosstalk impact on peripheral neuropathies. Together with previously reported data, these observations open new perspectives for deciphering glial mechanisms of neuronal function support.
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Affiliation(s)
- Chrysanthi Samara
- Department of Medical Genetics, University of Lausanne Lausanne, Switzerland
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66
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Dahlhoff M, Emrich D, Wolf E, Schneider MR. Increased activation of the epidermal growth factor receptor in transgenic mice overexpressing epigen causes peripheral neuropathy. Biochim Biophys Acta Mol Basis Dis 2013; 1832:2068-76. [PMID: 23899604 DOI: 10.1016/j.bbadis.2013.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 06/17/2013] [Accepted: 07/22/2013] [Indexed: 01/03/2023]
Abstract
In the mammalian nervous system, axons are commonly surrounded by myelin, a lipid-rich sheath that is essential for precise and rapid conduction of nerve impulses. In the peripheral nervous system (PNS), myelin sheaths are formed by Schwann cells which wrap around individual axons. While the tyrosine kinase receptors ERBB2 and ERBB3 are established mediators of peripheral myelination, less is known about the functions of the related epidermal growth factor receptor (EGFR) in the regulation of PNS myelination. Here, we report a peripheral neurodegenerative disease caused by increased EGFR activation. Specifically, we characterize a symmetric and distally pronounced, late-onset muscular atrophy in transgenic mice overexpressing the EGFR ligand epigen. Histological examination revealed a demyelinating neuropathy and axon degeneration, and molecular analysis of signaling pathways showed reduced protein kinase B (PKB, AKT) activation in the nerves of Epigen-tg mice, indicating that the muscular phenotype is secondary to PNS demyelination and axon degeneration. Crossing of Epigen-tg mice into an EGFR-deficient background revealed the pathology to be completely EGFR-dependent. This mouse line provides a new model for studying molecular events associated with early stages of peripheral neuropathies, an essential prerequisite for the development of successful therapeutic interventions.
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Affiliation(s)
- Maik Dahlhoff
- Institute of Molecular Animal Breeding and Biotechnology, Laboratory for Functional Genome Analysis (LAFUGA), Gene Center, LMU Munich, 81377 Munich, Germany.
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67
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Dobrowolny G, Aucello M, Molinaro M, Musarò A. Local expression of mIgf-1 modulates ubiquitin, caspase and CDK5 expression in skeletal muscle of an ALS mouse model. Neurol Res 2013; 30:131-6. [DOI: 10.1179/174313208x281235] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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68
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Tanisawa K, Mikami E, Fuku N, Honda Y, Honda S, Ohsawa I, Ito M, Endo S, Ihara K, Ohno K, Kishimoto Y, Ishigami A, Maruyama N, Sawabe M, Iseki H, Okazaki Y, Hasegawa-Ishii S, Takei S, Shimada A, Hosokawa M, Mori M, Higuchi K, Takeda T, Higuchi M, Tanaka M. Exome sequencing of senescence-accelerated mice (SAM) reveals deleterious mutations in degenerative disease-causing genes. BMC Genomics 2013; 14:248. [PMID: 23586671 PMCID: PMC3637625 DOI: 10.1186/1471-2164-14-248] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Accepted: 03/19/2013] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Senescence-accelerated mice (SAM) are a series of mouse strains originally derived from unexpected crosses between AKR/J and unknown mice, from which phenotypically distinct senescence-prone (SAMP) and -resistant (SAMR) inbred strains were subsequently established. Although SAMP strains have been widely used for aging research focusing on their short life spans and various age-related phenotypes, such as immune dysfunction, osteoporosis, and brain atrophy, the responsible gene mutations have not yet been fully elucidated. RESULTS To identify mutations specific to SAMP strains, we performed whole exome sequencing of 6 SAMP and 3 SAMR strains. This analysis revealed 32,019 to 38,925 single-nucleotide variants in the coding region of each SAM strain. We detected Ogg1 p.R304W and Mbd4 p.D129N deleterious mutations in all 6 of the SAMP strains but not in the SAMR or AKR/J strains. Moreover, we extracted 31 SAMP-specific novel deleterious mutations. In all SAMP strains except SAMP8, we detected a p.R473W missense mutation in the Ldb3 gene, which has been associated with myofibrillar myopathy. In 3 SAMP strains (SAMP3, SAMP10, and SAMP11), we identified a p.R167C missense mutation in the Prx gene, in which mutations causing hereditary motor and sensory neuropathy (Dejerine-Sottas syndrome) have been identified. In SAMP6 we detected a p.S540fs frame-shift mutation in the Il4ra gene, a mutation potentially causative of ulcerative colitis and osteoporosis. CONCLUSIONS Our data indicate that different combinations of mutations in disease-causing genes may be responsible for the various phenotypes of SAMP strains.
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Affiliation(s)
- Kumpei Tanisawa
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Tokyo, Itabashi, 173-0015, Japan
- Graduate School of Sport Sciences, Waseda University, Tokorozawa, 359-1192, Japan
| | - Eri Mikami
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Tokyo, Itabashi, 173-0015, Japan
- Graduate School of Sport Sciences, Waseda University, Tokorozawa, 359-1192, Japan
- Japan Society for the Promotion of Science, Tokyo, 102-8472, Japan
| | - Noriyuki Fuku
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Tokyo, Itabashi, 173-0015, Japan
| | - Yoko Honda
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Tokyo, Itabashi, 173-0015, Japan
| | - Shuji Honda
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Tokyo, Itabashi, 173-0015, Japan
| | - Ikuro Ohsawa
- Department of Biological Process of Aging, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Masafumi Ito
- Department of Molecular Gerontology, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Shogo Endo
- Aging Regulation Research Team, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Nagoya, 464-8602, Japan
| | - Kinji Ohno
- Department of Neurogenetics and Bioinformatics, Nagoya University Graduate School of Medicine, Nagoya, 466-8550, Japan
| | - Yuki Kishimoto
- Department of Aging Regulation, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Akihito Ishigami
- Department of Aging Regulation, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Naoki Maruyama
- Department of Aging Regulation, Tokyo Metropolitan Institute of Gerontology, Tokyo, 173-0015, Japan
| | - Motoji Sawabe
- Department of Pathology and Bioresource Center for Geriatric Research, Tokyo Metropolitan Institute of Gerontology, Tokyo, 1730015, Japan
| | - Hiroyoshi Iseki
- Research Center for Genomic Medicine, Saitama Medical University, Hidaka, 350-1241, Japan
| | - Yasushi Okazaki
- Research Center for Genomic Medicine, Saitama Medical University, Hidaka, 350-1241, Japan
| | - Sanae Hasegawa-Ishii
- Department of Pathology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, 480-0392, Japan
| | - Shiro Takei
- Department of Pathology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, 480-0392, Japan
| | - Atsuyoshi Shimada
- Department of Pathology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, 480-0392, Japan
| | - Masanori Hosokawa
- Department of Pathology, Institute for Developmental Research, Aichi Human Service Center, Kasugai, 480-0392, Japan
| | - Masayuki Mori
- Department of Aging Biology, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Matsumoto, 390-8621, Japan
| | - Keiichi Higuchi
- Department of Aging Biology, Institute on Aging and Adaptation, Shinshu University Graduate School of Medicine, Matsumoto, 390-8621, Japan
| | - Toshio Takeda
- The Council for SAM Research, Kyoto, 604-8856, Japan
| | - Mitsuru Higuchi
- Faculty of Sport Sciences, Waseda University, Tokorozawa, 359-1192, Japan
| | - Masashi Tanaka
- Department of Genomics for Longevity and Health, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Tokyo, Itabashi, 173-0015, Japan
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Abstract
The fundamental roles of Schwann cells during peripheral nerve formation and regeneration have been recognized for more than 100 years, but the cellular and molecular mechanisms that integrate Schwann cell and axonal functions continue to be elucidated. Derived from the embryonic neural crest, Schwann cells differentiate into myelinating cells or bundle multiple unmyelinated axons into Remak fibers. Axons dictate which differentiation path Schwann cells follow, and recent studies have established that axonal neuregulin1 signaling via ErbB2/B3 receptors on Schwann cells is essential for Schwann cell myelination. Extracellular matrix production and interactions mediated by specific integrin and dystroglycan complexes are also critical requisites for Schwann cell-axon interactions. Myelination entails expansion and specialization of the Schwann cell plasma membrane over millimeter distances. Many of the myelin-specific proteins have been identified, and transgenic manipulation of myelin genes have provided novel insights into myelin protein function, including maintenance of axonal integrity and survival. Cellular events that facilitate myelination, including microtubule-based protein and mRNA targeting, and actin based locomotion, have also begun to be understood. Arguably, the most remarkable facet of Schwann cell biology, however, is their vigorous response to axonal damage. Degradation of myelin, dedifferentiation, division, production of axonotrophic factors, and remyelination all underpin the substantial regenerative capacity of the Schwann cells and peripheral nerves. Many of these properties are not shared by CNS fibers, which are myelinated by oligodendrocytes. Dissecting the molecular mechanisms responsible for the complex biology of Schwann cells continues to have practical benefits in identifying novel therapeutic targets not only for Schwann cell-specific diseases but other disorders in which axons degenerate.
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Affiliation(s)
- Grahame J Kidd
- Department of Neuroscience, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA.
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70
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Kallenborn-Gerhardt W, Schröder K, Geisslinger G, Schmidtko A. NOXious signaling in pain processing. Pharmacol Ther 2012; 137:309-17. [PMID: 23146925 DOI: 10.1016/j.pharmthera.2012.11.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Accepted: 10/26/2012] [Indexed: 12/14/2022]
Abstract
Chronic pain affects millions of people and often causes major health problems. Accumulating evidence indicates that the production of reactive oxygen species (ROS), such as superoxide anion or hydrogen peroxide, is increased in the nociceptive system during chronic inflammatory and neuropathic pain, and that ROS can act as specific signaling molecules in pain processing. Reduction of ROS levels by administration of scavengers or antioxidant compounds attenuated the nociceptive behavior in various animal models of chronic pain. However, the sources of increased ROS production during chronic pain and the role of ROS in pain processing are poorly understood. Current work revealed pain-relevant functions of the Nox family of NADPH oxidases, a group of electron-transporting transmembrane enzymes whose sole function seems to be the generation of ROS. In particular, significant expression of the Nox family members Nox1, Nox2, and Nox4 in various cells of the nociceptive system has been discovered. Studies using knockout mice suggest that these Nox enzymes specifically contribute to distinct signaling pathways in chronic inflammatory and/or neuropathic pain states. Accordingly, targeting Nox1, Nox2, and Nox4 could be a novel strategy for the treatment of chronic pain. Currently selective inhibitors of Nox enzymes are being developed. Here, we introduce the distinct roles of Nox enzymes in pain processing, we summarize recent findings in the understanding of ROS-dependent signaling pathways in the nociceptive system, and we discuss potential analgesic properties of currently available Nox inhibitors.
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Affiliation(s)
- Wiebke Kallenborn-Gerhardt
- Pharmazentrum Frankfurt/ZAFES, Institut für Klinische Pharmakologie, Klinikum der Johann Wolfgang Goethe-Universität, 60590 Frankfurt am Main, Germany
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71
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Abstract
Reactive oxygen species (ROS) contribute to sensitization of pain pathways during neuropathic pain, but little is known about the primary sources of ROS production and how ROS mediate pain sensitization. Here, we show that the NADPH oxidase isoform Nox4, a major ROS source in somatic cells, is expressed in a subset of nonpeptidergic nociceptors and myelinated dorsal root ganglia neurons. Mice lacking Nox4 demonstrated a substantially reduced late-phase neuropathic pain behavior after peripheral nerve injury. The loss of Nox4 markedly attenuated injury-induced ROS production and dysmyelination processes of peripheral nerves. Moreover, persisting neuropathic pain behavior was inhibited after tamoxifen-induced deletion of Nox4 in adult transgenic mice. Our results suggest that Nox4 essentially contributes to nociceptive processing in neuropathic pain states. Accordingly, inhibition of Nox4 may provide a novel therapeutic modality for the treatment of neuropathic pain.
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72
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Wu L, Williams A, Delaney A, Sherman D, Brophy P. Increasing internodal distance in myelinated nerves accelerates nerve conduction to a flat maximum. Curr Biol 2012; 22:1957-61. [PMID: 23022068 PMCID: PMC3482659 DOI: 10.1016/j.cub.2012.08.025] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 08/09/2012] [Accepted: 08/14/2012] [Indexed: 11/17/2022]
Abstract
Predictions that conduction velocities are sensitive to the distance between nodes of Ranvier in myelinated axons have implications for nervous system function during growth and repair. Internodal lengths defined by Schwann cells in hindlimb nerves, for example, can undergo a 4-fold increase during mouse development, and regenerated nerves have internodes that are uniformly short. Nevertheless, the influence of internodal length on conduction speed has limited experimental support. Here, we examined this problem in mice expressing a mutant version of periaxin, a protein required for Schwann cell elongation. Importantly, elongation of mutant Schwann cells was retarded without significant derangements to myelination or axon caliber. In young mice with short mutant Schwann cells, nerve conduction velocity was reduced and motor function was impaired. This demonstrates a functional relationship between internodal distance and conduction speed. Moreover, as internodes lengthened during postnatal growth, conduction velocities recovered to normal values and mutant mice exhibited normal motor and sensory behavior. This restoration of function confirms a further prediction by Huxley and Stämpfli that conduction speeds should increase as internodal distances lengthen until a "flat maximum" is reached, beyond which no further gains in conduction velocity accrue.
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Affiliation(s)
- Lai Man N. Wu
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Anna Williams
- MRC Centre for Regenerative Medicine and Centre for Multiple Sclerosis Research, University of Edinburgh, Edinburgh EH16 4UU, UK
| | - Ada Delaney
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Diane L. Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
| | - Peter J. Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh EH16 4SB, UK
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73
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Azzedine H, Senderek J, Rivolta C, Chrast R. Molecular genetics of charcot-marie-tooth disease: from genes to genomes. Mol Syndromol 2012; 3:204-14. [PMID: 23293578 DOI: 10.1159/000343487] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of disorders of the peripheral nervous system, mainly characterized by distal muscle weakness and atrophy leading to motor handicap. With an estimated prevalence of 1 in 2,500, this condition is one of the most commonly inherited neurological disorders. Mutations in more than 30 genes affecting glial and/or neuronal functions have been associated with different forms of CMT leading to a substantial improvement in diagnostics of the disease and in the understanding of implicated pathophysiological mechanisms. However, recent data from systematic genetic screening performed in large cohorts of CMT patients indicated that molecular diagnosis could be established only in ∼50-70% of them, suggesting that additional genes are involved in this disease. In addition to providing an overview of genetic and functional data concerning various CMT forms, this review focuses on recent data generated through the use of highly parallel genetic technologies (SNP chips, sequence capture and next-generation DNA sequencing) in CMT families, and the current and future impact of these technologies on gene discovery and diagnostics of CMTs.
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Affiliation(s)
- H Azzedine
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
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74
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Azzedine H, Senderek J, Rivolta C, Chrast R. Molecular genetics of charcot-marie-tooth disease: from genes to genomes. Mol Syndromol 2012. [PMID: 23293578 DOI: 10.1159/000343487/msy-0003-0204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of disorders of the peripheral nervous system, mainly characterized by distal muscle weakness and atrophy leading to motor handicap. With an estimated prevalence of 1 in 2,500, this condition is one of the most commonly inherited neurological disorders. Mutations in more than 30 genes affecting glial and/or neuronal functions have been associated with different forms of CMT leading to a substantial improvement in diagnostics of the disease and in the understanding of implicated pathophysiological mechanisms. However, recent data from systematic genetic screening performed in large cohorts of CMT patients indicated that molecular diagnosis could be established only in ∼50-70% of them, suggesting that additional genes are involved in this disease. In addition to providing an overview of genetic and functional data concerning various CMT forms, this review focuses on recent data generated through the use of highly parallel genetic technologies (SNP chips, sequence capture and next-generation DNA sequencing) in CMT families, and the current and future impact of these technologies on gene discovery and diagnostics of CMTs.
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Affiliation(s)
- H Azzedine
- Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
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75
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Drp2 and periaxin form Cajal bands with dystroglycan but have distinct roles in Schwann cell growth. J Neurosci 2012; 32:9419-28. [PMID: 22764250 DOI: 10.1523/jneurosci.1220-12.2012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Cajal bands are cytoplasmic channels flanked by appositions where the abaxonal surface of Schwann cell myelin apposes and adheres to the overlying plasma membrane. These appositions contain a dystroglycan complex that includes periaxin and dystrophin-related protein 2 (Drp2). Loss of periaxin disrupts appositions and Cajal bands in Schwann cells and causes a severe demyelinating neuropathy in mouse and human. Here, we investigated the role of mouse Drp2 in apposition assembly and Cajal band function and compared it with periaxin. We show that periaxin and Drp2 are not only both required to form appositions, but they must also interact. Periaxin-Drp2 interaction is also required for Drp2 phosphorylation, but phosphorylation is not required for the assembly of appositions. Drp2 loss causes corresponding increases in Dystrophin family members, utrophin and dystrophin Dp116, although dystroglycan remains unchanged. We also show that all dystroglycan complexes in Schwann cells use the uncleaved form of β-dystroglycan. Drp2-null Schwann cells have disrupted appositions and Cajal bands, and they undergo focal hypermyelination and concomitant demyelination. Nevertheless, they do not have the short internodal lengths and associated reduced nerve conduction velocity seen in the absence of periaxin, showing that periaxin regulates Schwann cell elongation independent of its role in the dystroglycan complex. We conclude that the primary role of the dystroglycan complex in appositions is to stabilize and limit the radial growth of myelin.
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76
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Abstract
The prenatal and infantile neuropathies are an uncommon and complex group of conditions, most of which are genetic. Despite advances in diagnostic techniques, approximately half of children presenting in infancy remain without a specific diagnosis. This review focuses on inherited demyelinating neuropathies presenting in the first year of life. We clarify the nomenclature used in these disorders, review the clinical features of demyelinating forms of Charcot-Marie-Tooth disease with early onset, and discuss the demyelinating infantile neuropathies associated with central nervous system involvement. Useful clinical, neurophysiologic, and neuropathologic features in the diagnostic work-up of these conditions are also presented.
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Affiliation(s)
- Eppie M Yiu
- Children's Neuroscience Centre, Royal Children's Hospital, Flemington Road, Parkville, Victoria, Australia
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77
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Tokunaga S, Hashiguchi A, Yoshimura A, Maeda K, Suzuki T, Haruki H, Nakamura T, Okamoto Y, Takashima H. Late-onset Charcot-Marie-Tooth disease 4F caused by periaxin gene mutation. Neurogenetics 2012; 13:359-65. [PMID: 22847150 DOI: 10.1007/s10048-012-0338-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Accepted: 07/04/2012] [Indexed: 11/26/2022]
Abstract
We identified the main features of Charcot-Marie-Tooth (CMT) disease, type 4F, caused by a periaxin gene (PRX) mutation in Japanese patients. Periaxin is known as one of the key myelination molecules, forming tight junction between myelin loop and axon. We collected 427 DNA samples from individuals with CMT or CMT-related neuropathy, negative for PMP22 duplication. We investigated PRX mutations using a purpose-built resequencing array screen during the period 2006-2012. We detected two types of PRX mutations in three patients; one patient showed a novel homozygous p.D651N mutation and the other two showed homozygous p.R1070X mutation. All PRX mutations reported so far have been of nonsense or frameshift type. In this study, we found homozygous missense mutation p.D651N. Aspartate 651 is located in a repeat domain; its position might indicate an important function. PRX mutations usually lead to early-onset, autosomal-recessive demyelinating CMT neuropathy 4F (CMT4F) or Dejerine-Sottas disease; their clinical phenotypes are severe. In our three patients, the onset of the disease was at the age of 27 years or later, and their clinical phenotypes were milder compared with those reported in previous studies. We showed a variation of clinical phenotypes for CMT4F caused by a novel, nonsense PRX mutation.
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Affiliation(s)
- Shoko Tokunaga
- Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Sakuragaoka, Kagoshima City, Kagoshima, Japan
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78
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Ramirez JD, Barnes PRJ, Mills KR, Bennett DLH. Intermediate Charcot-Marie-Tooth disease due to a novel Trp101Stop myelin protein zero mutation associated with debilitating neuropathic pain. Pain 2012; 153:1763-1768. [PMID: 22704856 PMCID: PMC3399778 DOI: 10.1016/j.pain.2012.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 05/11/2012] [Accepted: 05/14/2012] [Indexed: 11/03/2022]
Abstract
We report an English kindred affected across 4 generations with a hereditary neuropathy associated with debilitating neuropathic pain as the main clinical feature. The principal finding on clinical examination was sensory loss, and there was variable motor dysfunction. Electrophysiological studies revealed mild features of demyelination with median conduction velocity in the intermediate range. There was an autosomal-dominant pattern of inheritance, and genetic testing revealed a novel heterozygous Trp101X mutation in exon 3 coding for a portion of the extracellular domain of myelin protein zero. This is predicted to lead to premature termination of translation. Myelin protein zero is a key structural component of compact myelin, and over 100 mutations in this protein have been reported, which can give rise to neuropathies with either axonal, demyelinating, or intermediate features encompassing a wide range of severity. Chronic pain is an increasingly recognised sequela of certain hereditary neuropathies and may be musculoskeletal or neuropathic in origin. In this kindred, the neuropathy was relatively mild in severity, however, neuropathic pain was an important and disabling outcome.
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Affiliation(s)
- Juan D Ramirez
- Wolfson Centre for Age-Related Diseases, King's College London, London, UK Medical Director's Office, Western Sussex Hospitals, Worthing, UK Department of Clinical Neurosciences, King's College, London, UK
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79
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Hossain S, de la Cruz-Morcillo MA, Sanchez-Prieto R, Almazan G. Mitogen-activated protein kinase p38 regulates krox-20 to direct schwann cell differentiation and peripheral myelination. Glia 2012; 60:1130-44. [DOI: 10.1002/glia.22340] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Accepted: 03/16/2012] [Indexed: 12/24/2022]
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80
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Goebbels S, Oltrogge JH, Wolfer S, Wieser GL, Nientiedt T, Pieper A, Ruhwedel T, Groszer M, Sereda MW, Nave KA. Genetic disruption of Pten in a novel mouse model of tomaculous neuropathy. EMBO Mol Med 2012; 4:486-99. [PMID: 22488882 PMCID: PMC3443946 DOI: 10.1002/emmm.201200227] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 02/16/2012] [Accepted: 02/17/2012] [Indexed: 01/01/2023] Open
Abstract
‘Tomacula’ and myelin outfoldings are striking neuropathological features of a diverse group of inherited demyelinating neuropathies. Whereas the underlying genetic defects are well known, the molecular mechanisms of tomacula formation have remained obscure. We hypothesized that they are caused by uncontrolled, excessive myelin membrane growth, a process, which is regulated in normal development by neuregulin-1/ErbB2, PI3 Kinase signalling and ERK/MAPK signalling. Here, we demonstrate by targeted disruption of Pten in Schwann cells that hyperactivation of the endogenous PI3 Kinase pathway causes focal hypermyelination, myelin outfoldings and tomacula, even when induced in adult animals by tamoxifen, and is associated with progressive peripheral neuropathy. Activated AKT kinase is associated with PtdIns(3,4,5)P3 at paranodal loops and Schmidt–Lanterman incisures. This striking myelin pathology, with features of human CMT type 4B1 and HNPP, is dependent on AKT/mTOR signalling, as evidenced by a significant amelioration of the pathology in mice treated with rapamycin. We suggest that regions of non-compact myelin are under lifelong protection by PTEN against abnormal membrane outgrowth, and that dysregulated phosphoinositide levels play a critical role in the pathology of tomaculous neuropathies.
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Affiliation(s)
- Sandra Goebbels
- Max-Planck-Institute of Experimental Medicine, Göttingen, Germany.
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81
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The nucleosome remodeling and deacetylase chromatin remodeling (NuRD) complex is required for peripheral nerve myelination. J Neurosci 2012; 32:1517-27. [PMID: 22302795 DOI: 10.1523/jneurosci.2895-11.2012] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Several key transcription factors and coregulators important to peripheral nerve myelination have been identified, but the contributions of specific chromatin remodeling complexes to peripheral nerve myelination have not been analyzed. Chromodomain helicase DNA-binding protein 4 (Chd4) is the core catalytic subunit of the nucleosome remodeling and deacetylase (NuRD) chromatin remodeling complex. Previous studies have shown Chd4 interacts with Nab (NGFI-A/Egr-binding) corepressors, which are required for early growth response 2 (Egr2/Krox20), to direct peripheral nerve myelination by Schwann cells. In this study, we examined the developmental importance of the NuRD complex in peripheral nerve myelination through the generation of conditional Chd4 knock-out mice in Schwann cells (Chd4(loxP/loxP); P0-cre). Chd4 conditional null mice were found to have delayed myelination, radial sorting defects, hypomyelination, and the persistence of promyelinating Schwann cells. Loss of Chd4 leads to elevated expression of immature Schwann cell genes (Id2, c-Jun, and p75), and sustained expression of the promyelinating Schwann cell gene, Oct6/Scip, without affecting the levels of Egr2/Krox20. Furthermore, Schwann cell proliferation is upregulated in Chd4-null sciatic nerve. In vivo chromatin immunoprecipitation studies reveal recruitment of Chd4 and another NuRD component, Mta2, to genes that are positively and negatively regulated by Egr2 during myelination. Together, these results underscore the necessity of Chd4 function to guide proper terminal differentiation of Schwann cells and implicate the NuRD chromatin remodeling complex as a requisite factor in timely and stable peripheral nerve myelination.
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82
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XIE KELIANG, JIA YINGPING, HU YING, SUN YANYAN, HOU LICHAO, WANG GUOLIN. Activation of notch signaling mediates the induction and maintenance of mechanical allodynia in a rat model of neuropathic pain. Mol Med Rep 2012; 12:639-44. [DOI: 10.3892/mmr.2015.3379] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 02/05/2015] [Indexed: 11/06/2022] Open
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83
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Espinós C, Calpena E, Martínez-Rubio D, Lupo V. Autosomal Recessive Charcot-Marie-Tooth Neuropathy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 724:61-75. [DOI: 10.1007/978-1-4614-0653-2_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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84
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Early demyelination of primary A-fibers induces a rapid-onset of neuropathic pain in rat. Neuroscience 2011; 200:186-98. [PMID: 22061425 DOI: 10.1016/j.neuroscience.2011.10.037] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/18/2011] [Accepted: 10/20/2011] [Indexed: 12/23/2022]
Abstract
Some types of peripheral neuropathic pain are associated with damage to myelin rather than to axons of primary sensory neurons. It is extremely important to develop selective demyelination animal models for understanding neuropathic pain caused by demyelination. We induced a rapid-onset and reversible demyelination of peripheral A-fibers and neuropathic pain behaviors in adult rats by a single injection of cobra venom into the sciatic nerve. The relation between A-fiber demyelination and the abnormal pain behaviors was investigated using this model. Microfilament recordings revealed that cobra venom selectively blocked A-fibers, but not C-fibers. Selective blockade of A-fibers may result from A-fiber demyelination at the site of venom injection as demonstrated by microscope examination. The axons of the demyelinated A-fibers appeared to be otherwise normal. Neuropathic pain behaviors appeared almost immediately after venom injection and lasted about 3 weeks. Electrophysiological studies indicated that venom injection induced loss of conduction in A-fibers, increased sensitivity of C-polymodal nociceptors to innocuous stimuli, and triggered spontaneous activity from both peripheral and central terminals of C-fiber nociceptors. Neurogenic inflammatory responses were also observed in the affected skin via Evan's Blue extravasation experiments. Both antidromic C-fiber spontaneous activity and neurogenic inflammation were substantially decreased by continuous A-fiber threshold electric stimuli applied proximally to the venom injection site. The data suggest that normal activity of peripheral A-fibers may produce inhibitory modulation of C-fiber polymodal nociceptors. Removal of inhibition to C-fiber polymodal nociceptors following demyelination of A-fibers may result in pain and neurogenic inflammation in the affected receptive field.
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85
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Maddala R, Skiba NP, Lalane R, Sherman DL, Brophy PJ, Rao PV. Periaxin is required for hexagonal geometry and membrane organization of mature lens fibers. Dev Biol 2011; 357:179-90. [PMID: 21745462 PMCID: PMC3164832 DOI: 10.1016/j.ydbio.2011.06.036] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Revised: 06/14/2011] [Accepted: 06/14/2011] [Indexed: 01/06/2023]
Abstract
Transparency of the ocular lens depends on symmetric packing and membrane organization of highly elongated hexagonal fiber cells. These cells possess an extensive, well-ordered cortical cytoskeleton to maintain cell shape and to anchor membrane components. Periaxin (Prx), a PDZ domain protein involved in myelin sheath stabilization, is also a component of adhaerens plaques in lens fiber cells. Here we show that Prx is expressed in lens fibers and exhibits maturation dependent redistribution, clustering discretely at the tricellular junctions in mature fiber cells. Prx exists in a macromolecular complex with proteins involved in membrane organization including ankyrin-B, spectrin, NrCAM, filensin, ezrin and desmoyokin. Importantly, Prx knockout mouse lenses were found to be softer and more easily deformed than normal lenses, revealing disruptions in fiber cell hexagonal packing, membrane skeleton and membrane stability. These observations suggest a key role for Prx in maturation, packing, and membrane organization of lens fiber cells. Hence, there may be functional parallels between the roles of Prx in membrane stabilization of the myelin sheath and the lens fiber cell.
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Affiliation(s)
- Rupalatha Maddala
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
| | - Nikolai P. Skiba
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
| | - Robert Lalane
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
| | - Diane L. Sherman
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Peter J. Brophy
- Centre for Neuroregeneration, University of Edinburgh, Edinburgh, UK
| | - Ponugoti V. Rao
- Department of Ophthalmology, Duke University School of Medicine, NC. USA
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, NC. USA
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86
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Ueda H, Ueda M. Lysophosphatidic acid as an initiator of neuropathic pain: biosynthesis and demyelination. ACTA ACUST UNITED AC 2011. [DOI: 10.2217/clp.10.88] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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87
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Nagai J, Uchida H, Matsushita Y, Yano R, Ueda M, Niwa M, Aoki J, Chun J, Ueda H. Autotaxin and lysophosphatidic acid1 receptor-mediated demyelination of dorsal root fibers by sciatic nerve injury and intrathecal lysophosphatidylcholine. Mol Pain 2010; 6:78. [PMID: 21062487 PMCID: PMC2989310 DOI: 10.1186/1744-8069-6-78] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Accepted: 11/09/2010] [Indexed: 12/15/2022] Open
Abstract
Background Although neuropathic pain is frequently observed in demyelinating diseases such as Guillain-Barré syndrome and multiple sclerosis, the molecular basis for the relationship between demyelination and neuropathic pain behaviors is poorly understood. Previously, we found that lysophosphatidic acid receptor (LPA1) signaling initiates sciatic nerve injury-induced neuropathic pain and demyelination. Results In the present study, we have demonstrated that sciatic nerve injury induces marked demyelination accompanied by myelin-associated glycoprotein (MAG) down-regulation and damage of Schwann cell partitioning of C-fiber-containing Remak bundles in the sciatic nerve and dorsal root, but not in the spinal nerve. Demyelination, MAG down-regulation and Remak bundle damage in the dorsal root were abolished in LPA1 receptor-deficient (Lpar1-/-) mice, but these alterations were not observed in sciatic nerve. However, LPA-induced demyelination in ex vivo experiments was observed in the sciatic nerve, spinal nerve and dorsal root, all which express LPA1 transcript and protein. Nerve injury-induced dorsal root demyelination was markedly attenuated in mice heterozygous for autotaxin (atx+/-), which converts lysophosphatidylcholine (LPC) to LPA. Although the addition of LPC to ex vivo cultures of dorsal root fibers in the presence of recombinant ATX caused potent demyelination, it had no significant effect in the absence of ATX. On the other hand, intrathecal injection of LPC caused potent dorsal root demyelination, which was markedly attenuated or abolished in atx+/- or Lpar1-/- mice. Conclusions These results suggest that LPA, which is converted from LPC by ATX, activates LPA1 receptors and induces dorsal root demyelination following nerve injury, which causes neuropathic pain.
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Affiliation(s)
- Jun Nagai
- Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan
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88
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Biological role of dystroglycan in Schwann cell function and its implications in peripheral nervous system diseases. J Biomed Biotechnol 2010; 2010:740403. [PMID: 20625412 PMCID: PMC2896880 DOI: 10.1155/2010/740403] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2009] [Accepted: 04/20/2010] [Indexed: 11/17/2022] Open
Abstract
Dystroglycan is a central component of the dystrophin-glycoprotein complex (DGC) that links extracellular matrix with cytoskeleton, expressed in a variety of fetal and adult tissues. Dystroglycan plays diverse roles in development and homeostasis including basement membrane formation, epithelial morphogenesis, membrane stability, cell polarization, and cell migration. In this paper, we will focus on biological role of dystroglycan in Schwann cell function, especially myelination. First, we review the molecular architecture of DGC in Schwann cell abaxonal membrane. Then, we will review the loss-of-function studies using targeted mutagenesis, which have revealed biological functions of each component of DGC in Schwann cells. Based on these findings, roles of dystroglycan in Schwann cell function, in myelination in particular, and its implications in diseases will be discussed in detail. Finally, in view of the fact that understanding the role of dystroglycan in Schwann cells is just beginning, future perspectives will be discussed.
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89
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Pedraza L, Huang JK, Colman D. Disposition of axonal caspr with respect to glial cell membranes: Implications for the process of myelination. J Neurosci Res 2010; 87:3480-91. [PMID: 19170162 DOI: 10.1002/jnr.22004] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Neurofascin-155 (NF155) and caspr are transmembrane proteins found at discrete locations early during development of the nervous system. NF155 is present in the oligodendrocyte cell body and processes, whereas caspr is on the axonal surface. In mature nerves, these proteins are clustered at paranodes, flanking the node of Ranvier. To understand how NF155 and caspr become localized to the paranodal regions of myelinated nerves, we have studied their distribution over time in myelinating cultures. Our observations indicate that these two proteins are recruited to the cell surface at the contact zone between axons and oligodendrocytes, where they trans-interact. This association explains the early pattern of caspr distribution, a helical coil that winds around the axon, resembling the turns of the myelin sheath. Caspr, an axonal membrane protein, therefore seems to move in register with the overlying myelinating cell via its interactions with myelin proteins. We suggest that NF155 is the glial cell membrane protein responsible for caspr distribution. The pair act as interacting partners on either side of the axoglial contact area. Most likely, there are other proteins on the axonal surface whose distribution is equally influenced by interaction with the nascent myelin sheath. The fact that caspr follows the movement of the spiraling membrane has a direct affect on the interpretation of the way in which myelin is formed.
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Affiliation(s)
- Liliana Pedraza
- Montreal Neurological Institute, Program in Neuroengineering, McGill University, Montreal, Quebec, Canada.
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90
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Abstract
Neuromuscular diseases can affect the survival of peripheral neurons, their axons extending to peripheral targets, their synaptic connections onto those targets, or the targets themselves. Examples include motor neuron diseases such as amyotrophic lateral sclerosis, peripheral neuropathies, such as Charcot-Marie-Tooth diseases, myasthenias, and muscular dystrophies. Characterizing these phenotypes in mouse models requires an integrated approach, examining both the nerve and the muscle histologically, anatomically, and functionally by electrophysiology. Defects observed at these levels can be related back to onset, severity, and progression, as assessed by "quality-of-life measures" including tests of gross motor performance such as gait or grip strength. This chapter describes methods for assessing neuromuscular disease models in mice, and how interpretation of these tests can be complicated by the inter-relatedness of the phenotypes.
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91
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Tan PL, Katsanis N. Thermosensory and mechanosensory perception in human genetic disease. Hum Mol Genet 2009; 18:R146-55. [PMID: 19808790 DOI: 10.1093/hmg/ddp412] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Peripheral sensory perception is established through an elaborate network of specialized neurons that mediate the translation of extraorganismal stimuli through the use of a broad array of receptors and downstream effector molecules. Studies of human genetic disorders, as well as mouse and other animal models, have identified some of the key molecules necessary for peripheral innervation and function. These findings have, in turn, yielded new insights into the developmental networks and homeostatic mechanisms necessary for the transformation of external stimuli into interpretable electrical impulses. In this review, we will summarize and discuss some of the genes/proteins implicated in two particular aspects of sensory perception, thermosensation and mechanosensation, highlighting pathways whose perturbation leads to both isolated and syndromic sensory deficits.
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Affiliation(s)
- Perciliz L Tan
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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92
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Abstract
Pain normally subserves a vital role in the survival of the organism, prompting the avoidance of situations associated with tissue damage. However, the sensation of pain can become dissociated from its normal physiological role. In conditions of neuropathic pain, spontaneous or hypersensitive pain behavior occurs in the absence of the appropriate stimuli. Our incomplete understanding of the mechanisms underlying chronic pain hypersensitivity accounts for the general ineffectiveness of currently available options for the treatment of chronic pain syndromes. Despite its complex pathophysiological nature, it is clear that neuropathic pain is associated with short- and long-term changes in the excitability of sensory neurons in the dorsal root ganglia (DRG) as well as their central connections. Recent evidence suggests that the upregulated expression of inflammatory cytokines in association with tissue damage or infection triggers the observed hyperexcitability of pain sensory neurons. The actions of inflammatory cytokines synthesized by DRG neurons and associated glial cells, as well as by astrocytes and microglia in the spinal cord, can produce changes in the excitability of nociceptive sensory neurons. These changes include rapid alterations in the properties of ion channels expressed by these neurons, as well as longer-term changes resulting from new gene transcription. In this chapter we review the diverse changes produced by inflammatory cytokines in the behavior of sensory neurons in the context of chronic pain syndromes.
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93
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Henry MA, Luo S, Foley BD, Rzasa RS, Johnson LR, Levinson SR. Sodium channel expression and localization at demyelinated sites in painful human dental pulp. THE JOURNAL OF PAIN 2009; 10:750-8. [PMID: 19559391 PMCID: PMC2750027 DOI: 10.1016/j.jpain.2009.01.264] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Revised: 12/09/2008] [Accepted: 01/12/2009] [Indexed: 11/18/2022]
Abstract
UNLABELLED The expression of sodium channels (NaCh(s)) change after inflammatory and nerve lesions, and this change has been implicated in the generation of pain states. Here we examine NaCh expression within nerve fibers from normal and painful extracted human teeth with special emphasis on their localization within large accumulations, like those seen at nodes of Ranvier. Pulpal tissue sections from normal wisdom teeth and from teeth with large carious lesions associated with severe and spontaneous pain were double-stained with pan-specific NaCh antibody and caspr (paranodal protein used to visualize nodes of Ranvier) antibody, while additional sections were triple-stained with NaCh, caspr and myelin basic protein (MBP) antibodies. Z-series of images were obtained with the confocal microscope and evaluated with NIH ImageJ software to quantify the density and size of NaCh accumulations, and to characterize NaCh localization at caspr-identified typical and atypical nodal sites. Although the results showed variability in the overall density and size of NaCh accumulations in painful samples, a common finding included the remodeling of NaChs at atypical nodal sites. This remodeling of NaChs included prominent NaCh expression within nerve regions that showed a selective loss of MBP staining in a pattern consistent with a demyelinating process. PERSPECTIVE This study identifies the remodeling of NaChs at demyelinated sites within the painful human dental pulp and suggests that the contribution of NaChs to spontaneous pulpal pain generation may be dependant not only on total NaCh density but may also be related to NaCh expression at atypical nodal sites.
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Affiliation(s)
- Michael A Henry
- Department of Endodontics, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA.
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Salim C, Boxberg YV, Alterio J, Féréol S, Nothias F. The giant protein AHNAK involved in morphogenesis and laminin substrate adhesion of myelinating Schwann cells. Glia 2009; 57:535-49. [PMID: 18837049 DOI: 10.1002/glia.20782] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Within the nervous system, expression of the intriguing giant protein AHNAK had been reported so far only for blood-brain barrier forming vascular endothelium. In a screen for genes upregulated after spinal cord injury, we recently identified ahnak as being highly expressed by non-neuronal cells invading the lesion, delimiting the interior surface of cystic cavities in front of barrier-forming astrocytes. Here, we show for the first time that AHNAK is constitutively expressed in peripheral nervous system, notably by myelinating Schwann cells (SCs), in which we investigated its function. During sciatic nerve development, AHNAK is redistributed from adaxonal toward abaxonal SC compartments in contact with basement membrane. AHNAK labeling on myelinated fibers from adult nerve delineates the so-called "Cajal bands," constituting the residual peripheral SC cytoplasm. Its distribution pattern is complementary to that of periaxin, known to be involved in the myelination process. In vitro, nonconfluent cultured primary SCs seeded on laminin express high levels of AHNAK concentrated in their processes, whereas at confluence, AHNAK is downregulated together with laminin receptor dystroglycan. AHNAK silencing by siRNA interference affects SC morphology and laminin-substrate attachment, as well as expression and distribution of dystroglycan. Thus, our results clearly show the implication of AHNAK in SC adhesion to laminin, probably via targeting of the dystroglycan-associated receptor complex. These findings are of high interest regarding the importance of SC-basal lamina interactions for myelination and myelin maintenance, and open up new perspectives for investigations of the molecular mechanisms underlying demyelinating neuropathies.
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Affiliation(s)
- Claudio Salim
- Centre National de la Recherche Scientifique (CNRS), UMR7101, Laboratoire de Neurobiologie des Signaux Intercellulaires, and Université Pierre et Marie Curie, Université Paris 06, IFR-83, Paris, France
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95
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A laminin-2, dystroglycan, utrophin axis is required for compartmentalization and elongation of myelin segments. J Neurosci 2009; 29:3908-19. [PMID: 19321787 DOI: 10.1523/jneurosci.5672-08.2009] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Animal and plant cells compartmentalize to perform morphogenetic functions. Compartmentalization of myelin-forming Schwann cells may favor elongation of myelin segments to the size required for efficient conduction of nerve impulses. Compartments in myelinated fibers were described by Ramón y Cajal and depend on periaxin, mutated in the hereditary neuropathy Charcot-Marie-Tooth disease type 4F (Charcot-Marie-Tooth 4F). Lack of periaxin in mice causes loss of compartments, formation of short myelin segments (internodes) and reduced nerve conduction velocity. How compartments are formed and maintained, and their relevance to human neuropathies is largely unknown. Here we show that formation of compartments around myelin is driven by the actin cytoskeleton, and maintained by actin and tubulin fences through linkage to the dystroglycan complex. Compartmentalization and establishment of correct internodal length requires the presence of glycosylated dystroglycan, utrophin and extracellular laminin-2/211. A neuropathic patient with reduced internodal length and nerve conduction velocity because of absence of laminin-2/211 (congenital muscular dystrophy 1A) also shows abnormal compartmentalization. These data link formation of compartments through a laminin2, dystroglycan, utrophin, actin axis to internodal length, and provide a common pathogenetic mechanism for two inherited human neuropathies. Other cell types may exploit dystroglycan complexes in similar fashions to create barriers and compartments.
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96
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Chernousov MA, Yu WM, Chen ZL, Carey DJ, Strickland S. Regulation of Schwann cell function by the extracellular matrix. Glia 2009; 56:1498-1507. [PMID: 18803319 DOI: 10.1002/glia.20740] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Laminins and collagens are extracellular matrix proteins that play essential roles in peripheral nervous system development. Laminin signals regulate Schwann cell proliferation and survival as well as actin cytoskeleton dynamics, which are essential steps for radial sorting and myelination of peripheral axons by Schwann cells. Collagen and their receptors promote Schwann cell adhesion, spreading, and myelination as well as neurite outgrowth. In this article, we will review the recent advances in the studies of laminin and collagen function in Schwann cell development.
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Abstract
PURPOSE OF REVIEW Chemokines are central to the innate immune response following tissue damage, injury and some diseases. The function of chemokines in nervous system autoimmune diseases has been long recognized. There is also growing evidence that disease-associated or injury-induced functional expression of chemokines/receptors in both neural and nonneural elements of the peripheral nervous system play crucial roles in the pathophysiology of chronic pain. RECENT FINDINGS Chemokine involvement in neuropathic pain processing has recently been established in animal models. Evidence of chemokine contribution to chronic pain includes the upregulation of monocyte chemoattractant protein-1 (MCP-1/CCL2) and its respective receptor, CCR2, in many subpopulations of sensory neurons. Activation of CCR2 by MCP-1 elicits membrane depolarization, triggers action potentials and sensitizes nociceptors via transactivation of transient receptor potential channels TRPA1 and TRPV1. Increased signaling by stromal-derived factor-1 (SDF-1/CXCL12) and its receptor, CXCR4, has been shown to contribute to chronic pain behavior. The use of specific chemokine receptor antagonists for CCR2 and CXCR4 successfully reverses nociceptive pain behavior. SUMMARY Our results suggest that specific chemokines/receptors are upregulated by sensory neurons following peripheral nerve injury and appear to participate in neural signal processing leading to chronic pain states. Taken together, chemokines and their receptors are potential targets for development of novel therapeutics.
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98
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Zonta B, Tait S, Melrose S, Anderson H, Harroch S, Higginson J, Sherman DL, Brophy PJ. Glial and neuronal isoforms of Neurofascin have distinct roles in the assembly of nodes of Ranvier in the central nervous system. ACTA ACUST UNITED AC 2008; 181:1169-77. [PMID: 18573915 PMCID: PMC2442198 DOI: 10.1083/jcb.200712154] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Rapid nerve impulse conduction in myelinated axons requires the concentration of voltage-gated sodium channels at nodes of Ranvier. Myelin-forming oligodendrocytes in the central nervous system (CNS) induce the clustering of sodium channels into nodal complexes flanked by paranodal axoglial junctions. However, the molecular mechanisms for nodal complex assembly in the CNS are unknown. Two isoforms of Neurofascin, neuronal Nfasc186 and glial Nfasc155, are components of the nodal and paranodal complexes, respectively. Neurofascin-null mice have disrupted nodal and paranodal complexes. We show that transgenic Nfasc186 can rescue the nodal complex when expressed in Nfasc−/− mice in the absence of the Nfasc155–Caspr–Contactin adhesion complex. Reconstitution of the axoglial adhesion complex by expressing transgenic Nfasc155 in oligodendrocytes also rescues the nodal complex independently of Nfasc186. Furthermore, the Nfasc155 adhesion complex has an additional function in promoting the migration of myelinating processes along CNS axons. We propose that glial and neuronal Neurofascins have distinct functions in the assembly of the CNS node of Ranvier.
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Affiliation(s)
- Barbara Zonta
- Centre for Neuroscience Research, Royal Dick School of Veterinary Studies, University of Edinburgh, Edinburgh EH9 1QH, Scotland, UK
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99
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Abstract
Myelin formation around axons increases nerve conduction velocity and influences both the structure and function of the myelinated axon. In the peripheral nervous system, demyelinating forms of hereditary Charcot-Marie-Tooth (CMT) diseases cause reduced nerve conduction velocity initially and ultimately axonal degeneration. Several mouse models of CMT diseases have been generated, allowing the study of the consequences of disrupting Schwann cell function on peripheral nerve fibers. Nevertheless, the effect of demyelination at the level of the neuromuscular synapse has been largely overlooked. Here we show that in mice lacking functional Periaxin (Prx) genes, a model of a recessive type of CMT disease known as CMT4F, neuromuscular junctions (NMJs) develop profound morphological changes in the preterminal region of motor axons. These changes include extensive preterminal branches that originate in demyelinated regions of the nerve fiber and axonal swellings associated with residually-myelinated regions of the fiber. Using intracellular recording from muscle fibers we detected asynchronous failure of action potential transmission at high but not low stimulation frequencies, a phenomenon consistent with branch point failure. Taken together, our morphological and electrophysiological findings suggest that preterminal branching due to segmental demyelination near the neuromuscular synapse in Periaxin KO mice may underlie some characteristics of disabilities, including coordination deficits, present in this mouse model of CMT disease. These results reveal the importance of studying how demyelinating diseases might influence NMJ function and contribute to clinical disability.
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Ueda H. Peripheral mechanisms of neuropathic pain - involvement of lysophosphatidic acid receptor-mediated demyelination. Mol Pain 2008; 4:11. [PMID: 18377664 PMCID: PMC2365930 DOI: 10.1186/1744-8069-4-11] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Accepted: 04/01/2008] [Indexed: 01/23/2023] Open
Abstract
Recent advances in pain research provide a clear picture for the molecular mechanisms of acute pain; substantial information concerning plasticity that occurs during neuropathic pain has also become available. The peripheral mechanisms responsible for neuropathic pain are found in the altered gene/protein expression of primary sensory neurons. With damage to peripheral sensory fibers, a variety of changes in pain-related gene expression take place in dorsal root ganglion neurons. These changes, or plasticity, might underlie unique neuropathic pain-specific phenotype modifications - decreased unmyelinated-fiber functions, but increased myelinated A-fiber functions. Another characteristic change is observed in allodynia, the functional change of tactile to nociceptive perception. Throughout a series of studies, using novel nociceptive tests to characterize sensory-fiber or pain modality-specific nociceptive behaviors, it was demonstrated that communication between innocuous and noxious sensory fibers might play a role in allodynia mechanisms. Because neuropathic pain in peripheral and central demyelinating diseases develops as a result of aberrant myelination in experimental animals, demyelination seems to be a key mechanism of plasticity in neuropathic pain. More recently, we discovered that lysophosphatidic acid receptor activation initiates neuropathic pain, as well as possible peripheral mechanism of demyelination after nerve injury. These results lead to further hypotheses of physical communication between innocuous Abeta- and noxious C- or Adelta-fibers to influence the molecular mechanisms of allodynia.
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Affiliation(s)
- Hiroshi Ueda
- Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, 1-14 Bunkyo-machi, Nagasaki 852-8521, Japan.
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