1
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Horvath R, Medina J, Reilly MM, Shy ME, Zuchner S. Peripheral neuropathy in mitochondrial disease. HANDBOOK OF CLINICAL NEUROLOGY 2023; 194:99-116. [PMID: 36813324 DOI: 10.1016/b978-0-12-821751-1.00014-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
Mitochondria are essential for the health and viability of both motor and sensory neurons and their axons. Processes that disrupt their normal distribution and transport along axons will likely cause peripheral neuropathies. Similarly, mutations in mtDNA or nuclear encoded genes result in neuropathies that either stand alone or are part of multisystem disorders. This chapter focuses on the more common genetic forms and characteristic clinical phenotypes of "mitochondrial" peripheral neuropathies. We also explain how these various mitochondrial abnormalities cause peripheral neuropathy. In a patient with a neuropathy either due to a mutation in a nuclear or an mtDNA gene, clinical investigations aim to characterize the neuropathy and make an accurate diagnosis. In some patients, this may be relatively straightforward, where a clinical assessment and nerve conduction studies followed by genetic testing is all that is needed. In others, multiple investigations including a muscle biopsy, CNS imaging, CSF analysis, and a wide range of metabolic and genetic tests in blood and muscle may be needed to establish diagnosis.
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Affiliation(s)
- Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, John van Geest Centre for Brain Repair, Cambridge, United Kingdom.
| | - Jessica Medina
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Mary M Reilly
- MRC Centre for Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, United States
| | - Stephan Zuchner
- Dr. John T. Macdonald Foundation Department of Human Genetics and John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, United States
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2
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Yamazaki R, Osanai Y, Kouki T, Shinohara Y, Huang JK, Ohno N. Macroscopic detection of demyelinated lesions in mouse PNS with neutral red dye. Sci Rep 2021; 11:16906. [PMID: 34413421 PMCID: PMC8377033 DOI: 10.1038/s41598-021-96395-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 08/10/2021] [Indexed: 11/24/2022] Open
Abstract
Lysophosphatidylcholine (LPC)-induced demyelination is a versatile animal model that is frequently used to identify and examine molecular pathways of demyelination and remyelination in the central (CNS) and peripheral nervous system (PNS). However, identification of focally demyelinated lesion had been difficult and usually required tissue fixation, sectioning and histological analysis. Recently, a method for labeling and identification of demyelinated lesions in the CNS by intraperitoneal injection of neutral red (NR) dye was developed. However, it remained unknown whether NR can be used to label demyelinated lesions in PNS. In this study, we generated LPC-induced demyelination in sciatic nerve of mice, and demonstrated that the demyelinated lesions at the site of LPC injection were readily detectable at 7 days postlesion (dpl) by macroscopic observation of NR labeling. Moreover, NR staining gradually decreased from 7 to 21 dpl over the course of remyelination. Electron microscopy analysis of NR-labeled sciatic nerves at 7 dpl confirmed demyelination and myelin debris in lesions. Furthermore, fluorescence microscopy showed NR co-labeling with activated macrophages and Schwann cells in the PNS lesions. Together, NR labeling is a straightforward method that allows the macroscopic detection of demyelinated lesions in sciatic nerves after LPC injection.
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Affiliation(s)
- Reiji Yamazaki
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan.
| | - Yasuyuki Osanai
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Tom Kouki
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Yoshiaki Shinohara
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Jeffrey K Huang
- Department of Biology and Center for Cell Reprogramming, Georgetown University, Washington, DC, 20057, USA
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan
- Division of Ultrastructural Research, National Institute for Physiological Sciences, Okazaki, Japan
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3
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Saiki T, Nakamura N, Miyabe M, Ito M, Minato T, Sango K, Matsubara T, Naruse K. The Effects of Insulin on Immortalized Rat Schwann Cells, IFRS1. Int J Mol Sci 2021; 22:ijms22115505. [PMID: 34071138 PMCID: PMC8197103 DOI: 10.3390/ijms22115505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 05/18/2021] [Accepted: 05/19/2021] [Indexed: 01/02/2023] Open
Abstract
Schwann cells play an important role in peripheral nerve function, and their dysfunction has been implicated in the pathogenesis of diabetic neuropathy and other demyelinating diseases. The physiological functions of insulin in Schwann cells remain unclear and therefore define the aim of this study. By using immortalized adult Fischer rat Schwann cells (IFRS1), we investigated the mechanism of the stimulating effects of insulin on the cell proliferation and expression of myelin proteins (myelin protein zero (MPZ) and myelin basic protein (MBP). The application of insulin to IFRS1 cells increased the proliferative activity and induced phosphorylation of Akt and ERK, but not P38-MAPK. The proliferative potential of insulin-stimulated IFRS1 was significantly suppressed by the addition of LY294002, a PI3 kinase inhibitor. The insulin-stimulated increase in MPZ expression was significantly suppressed by the addition of PD98059, a MEK inhibitor. Furthermore, insulin-increased MBP expression was significantly suppressed by the addition of LY294002. These findings suggest that both PI3-K/Akt and ERK/MEK pathways are involved in insulin-induced cell growth and upregulation of MPZ and MBP in IFRS1 Schwann cells.
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Affiliation(s)
- Tomokazu Saiki
- Department of Pharmacy, Aichi Gakuin University Dental Hospital, Nagoya 464-8651, Japan;
| | - Nobuhisa Nakamura
- Department of Internal Medicine, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan; (M.M.); (M.I.); (T.M.); (K.N.)
- Correspondence: ; Tel.: +81-52-759-2111; Fax: +81-52-759-2168
| | - Megumi Miyabe
- Department of Internal Medicine, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan; (M.M.); (M.I.); (T.M.); (K.N.)
| | - Mizuho Ito
- Department of Internal Medicine, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan; (M.M.); (M.I.); (T.M.); (K.N.)
| | - Tomomi Minato
- Department of Clinical Laboratory, Aichi Gakuin University Dental Hospital, Nagoya 464-8651, Japan;
| | - Kazunori Sango
- Diabetic Neuropathy Project, Department of Diseases and Infection, Tokyo Metropolitan Institute of Medical Science, Tokyo 156-8506, Japan;
| | - Tatsuaki Matsubara
- Department of Internal Medicine, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan; (M.M.); (M.I.); (T.M.); (K.N.)
| | - Keiko Naruse
- Department of Internal Medicine, School of Dentistry, Aichi Gakuin University, Nagoya 464-8651, Japan; (M.M.); (M.I.); (T.M.); (K.N.)
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4
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Otani Y, Ohno N, Cui J, Yamaguchi Y, Baba H. Upregulation of large myelin protein zero leads to Charcot-Marie-Tooth disease-like neuropathy in mice. Commun Biol 2020; 3:121. [PMID: 32170207 PMCID: PMC7070019 DOI: 10.1038/s42003-020-0854-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Accepted: 02/24/2020] [Indexed: 01/01/2023] Open
Abstract
Charcot–Marie–Tooth (CMT) disease is a hereditary neuropathy mainly caused by gene mutation of peripheral myelin proteins including myelin protein zero (P0, MPZ). Large myelin protein zero (L-MPZ) is an isoform of P0 that contains an extended polypeptide synthesized by translational readthrough at the C-terminus in tetrapods, including humans. The physiological role of L-MPZ and consequences of an altered L-MPZ/P0 ratio in peripheral myelin are not known. To clarify this, we used genome editing to generate a mouse line (L-MPZ mice) that produced L-MPZ instead of P0. Motor tests and electrophysiological, immunohistological, and electron microscopy analyses show that homozygous L-MPZ mice exhibit CMT-like phenotypes including thin and/or loose myelin, increased small-caliber axons, and disorganized axo–glial interactions. Heterozygous mice show a milder phenotype. These results highlight the importance of an appropriate L-MPZ/P0 ratio and show that aberrant readthrough of a myelin protein causes neuropathy. Otani et al. show that upregulation of large myelin protein zero (L-MPZ), an isoform of myelin protein zero (P0) which contains an extended polypeptide synthesized by translational readthrough, can cause neuropathy, using mice that produce L-MPZ instead of P0. This study suggests the importance of keeping L-MPZ low for the proper functioning of myelin.
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Affiliation(s)
- Yoshinori Otani
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Nobuhiko Ohno
- Department of Anatomy, Division of Histology and Cell Biology, School of Medicine, Jichi Medical University, Shimotsuke, Japan.,Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, Okazaki, Japan
| | - Jingjing Cui
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
| | - Yoshihide Yamaguchi
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan.
| | - Hiroko Baba
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Japan
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5
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Moss KR, Höke A. Targeting the programmed axon degeneration pathway as a potential therapeutic for Charcot-Marie-Tooth disease. Brain Res 2019; 1727:146539. [PMID: 31689415 DOI: 10.1016/j.brainres.2019.146539] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 10/24/2019] [Accepted: 10/30/2019] [Indexed: 12/14/2022]
Abstract
The programmed axon degeneration pathway has emerged as an important process contributing to the pathogenesis of several neurological diseases. The most crucial events in this pathway include activation of the central executioner SARM1 and NAD+ depletion, which leads to an energetic failure and ultimately axon destruction. Given the prevalence of this pathway, it is not surprising that inhibitory therapies are currently being developed in order to treat multiple neurological diseases with the same therapy. Charcot-Marie-Tooth disease (CMT) is a heterogeneous group of neurological diseases that may also benefit from this therapeutic approach. To evaluate the appropriateness of this strategy, the contribution of the programmed axon degeneration pathway to the pathogenesis of different CMT subtypes is being actively investigated. The subtypes CMT1A, CMT1B and CMT2D are the first to have been examined. Based on the results from these studies and advances in developing therapies to block the programmed axon degeneration pathway, promising therapeutics for CMT are now on the horizon.
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Affiliation(s)
- Kathryn R Moss
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Ahmet Höke
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD, United States.
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6
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Ackerman SD, Luo R, Poitelon Y, Mogha A, Harty BL, D'Rozario M, Sanchez NE, Lakkaraju AKK, Gamble P, Li J, Qu J, MacEwan MR, Ray WZ, Aguzzi A, Feltri ML, Piao X, Monk KR. GPR56/ADGRG1 regulates development and maintenance of peripheral myelin. J Exp Med 2018; 215:941-961. [PMID: 29367382 PMCID: PMC5839751 DOI: 10.1084/jem.20161714] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Revised: 11/03/2017] [Accepted: 12/15/2017] [Indexed: 01/26/2023] Open
Abstract
This study identifies GPR56/ADGRG1 as a conserved regulator of peripheral nervous system myelination and defines a novel interacting partner of GPR56: plectin. This study is directly relevant to human health because mutations in GPR56 and PLECTIN cause diseases with neuropathic symptoms. Myelin is a multilamellar sheath generated by specialized glia called Schwann cells (SCs) in the peripheral nervous system (PNS), which serves to protect and insulate axons for rapid neuronal signaling. In zebrafish and rodent models, we identify GPR56/ADGRG1 as a conserved regulator of PNS development and health. We demonstrate that, during SC development, GPR56-dependent RhoA signaling promotes timely radial sorting of axons. In the mature PNS, GPR56 is localized to distinct SC cytoplasmic domains, is required to establish proper myelin thickness, and facilitates organization of the myelin sheath. Furthermore, we define plectin—a scaffolding protein previously linked to SC domain organization, myelin maintenance, and a series of disorders termed “plectinopathies”—as a novel interacting partner of GPR56. Finally, we show that Gpr56 mutants develop progressive neuropathy-like symptoms, suggesting an underlying mechanism for peripheral defects in some human patients with GPR56 mutations. In sum, we define Gpr56 as a new regulator in the development and maintenance of peripheral myelin.
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Affiliation(s)
- Sarah D Ackerman
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Rong Luo
- Division of Newborn Medicine, Department of Medicine, Children's Hospital and Harvard Medical School, Boston, MA
| | - Yannick Poitelon
- Departments of Biochemistry and Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY
| | - Amit Mogha
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Breanne L Harty
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Mitchell D'Rozario
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | - Nicholas E Sanchez
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
| | | | - Paul Gamble
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO
| | - Jun Li
- Department of Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY.,New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, NY
| | - Jun Qu
- Department of Pharmaceutical Sciences, University at Buffalo, State University of New York, Buffalo, NY.,New York State Center of Excellence in Bioinformatics and Life Sciences, Buffalo, NY
| | - Matthew R MacEwan
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO
| | - Wilson Zachary Ray
- Department of Neurosurgery, Washington University School of Medicine, St. Louis, MO.,Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zurich, Zürich, Switzerland
| | - M Laura Feltri
- Departments of Biochemistry and Neurology, Hunter James Kelly Research Institute, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, State University of New York, Buffalo, NY
| | - Xianhua Piao
- Division of Newborn Medicine, Department of Medicine, Children's Hospital and Harvard Medical School, Boston, MA
| | - Kelly R Monk
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO
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7
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Yoshimura T, Hayashi A, Handa-Narumi M, Yagi H, Ohno N, Koike T, Yamaguchi Y, Uchimura K, Kadomatsu K, Sedzik J, Kitamura K, Kato K, Trapp BD, Baba H, Ikenaka K. GlcNAc6ST-1 regulates sulfation of N-glycans and myelination in the peripheral nervous system. Sci Rep 2017; 7:42257. [PMID: 28186137 PMCID: PMC5301494 DOI: 10.1038/srep42257] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/05/2017] [Indexed: 01/09/2023] Open
Abstract
Highly specialized glial cells wrap axons with a multilayered myelin membrane in vertebrates. Myelin serves essential roles in the functioning of the nervous system. Axonal degeneration is the major cause of permanent neurological disability in primary myelin diseases. Many glycoproteins have been identified in myelin, and a lack of one myelin glycoprotein results in abnormal myelin structures in many cases. However, the roles of glycans on myelin glycoproteins remain poorly understood. Here, we report that sulfated N-glycans are involved in peripheral nervous system (PNS) myelination. PNS myelin glycoproteins contain highly abundant sulfated N-glycans. Major sulfated N-glycans were identified in both porcine and mouse PNS myelin, demonstrating that the 6-O-sulfation of N-acetylglucosamine (GlcNAc-6-O-sulfation) is highly conserved in PNS myelin between these species. P0 protein, the most abundant glycoprotein in PNS myelin and mutations in which at the glycosylation site cause Charcot-Marie-Tooth neuropathy, has abundant GlcNAc-6-O-sulfated N-glycans. Mice deficient in N-acetylglucosamine-6-O-sulfotransferase-1 (GlcNAc6ST-1) failed to synthesize sulfated N-glycans and exhibited abnormal myelination and axonal degeneration in the PNS. Taken together, this study demonstrates that GlcNAc6ST-1 modulates PNS myelination and myelinated axonal survival through the GlcNAc-6-O-sulfation of N-glycans on glycoproteins. These findings may provide novel insights into the pathogenesis of peripheral neuropathy.
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Affiliation(s)
- Takeshi Yoshimura
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa 240-0193, Japan
| | - Akiko Hayashi
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Mai Handa-Narumi
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa 240-0193, Japan
| | - Hirokazu Yagi
- Department of Structural Biology and Biomolecular Engineering, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi 467-8603, Japan
| | - Nobuhiko Ohno
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa 240-0193, Japan
| | - Takako Koike
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Yoshihide Yamaguchi
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Kenji Uchimura
- Department of Biochemistry, Graduate School of Medicine, Nagoya University, Nagoya, Aichi 466-8550, Japan
| | - Kenji Kadomatsu
- Department of Biochemistry, Graduate School of Medicine, Nagoya University, Nagoya, Aichi 466-8550, Japan
| | - Jan Sedzik
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Chemical Engineering and Technology, Protein Crystallization Facility, Royal Institute of Technology, KTH, Stockholm 10044, Sweden
| | - Kunio Kitamura
- Faculty of Health and Medical Care, Saitama Medical University, Hidaka, Saitama 350-1241, Japan
| | - Koichi Kato
- Department of Structural Biology and Biomolecular Engineering, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Aichi 467-8603, Japan
- Institute for Molecular Science and Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Bruce D. Trapp
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, OH 44195, USA
| | - Hiroko Baba
- Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences, Hachioji, Tokyo 192-0392, Japan
| | - Kazuhiro Ikenaka
- Division of Neurobiology and Bioinformatics, National Institute for Physiological Sciences, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
- Department of Physiological Sciences, School of Life Sciences, SOKENDAI (The Graduate University for Advanced Studies), Hayama, Kanagawa 240-0193, Japan
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8
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An oral NaV1.8 blocker improves motor function in mice completely deficient of myelin protein P0. Neurosci Lett 2016; 632:33-8. [PMID: 27530546 DOI: 10.1016/j.neulet.2016.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 08/11/2016] [Accepted: 08/12/2016] [Indexed: 01/06/2023]
Abstract
Mice deficient of myelin protein P0 are established models of demyelinating Charcot-Marie-Tooth (CMT) disease. Dysmyelination in these mice is associated with an ectopic expression of the sensory neuron specific sodium channel isoform NaV1.8 on motor axons. We reported that in P0+/-, a model of CMT1B, the membrane dysfunction could be acutely improved by a novel oral NaV1.8 blocker referred to as Compound 31 (C31, Bioorg. Med. Chem. Lett. 2010, 20, 6812; AbbVie Inc.). The aim of this study was to investigate the extent to which C31 treatment could also improve the motor axon function in P0-/-, a CMT model with a much more severe neuropathy. We found that the progressive impairment of motor performance from 1 to 4 months of age in P0-/- could be acutely reversed by C31 treatment. The effect was associated with an improvement of the amplitude of the plantar CMAP evoked by tibial nerve stimulation. The corresponding motor nerve excitability studies by "threshold tracking" showed changes after C31 consistent with attenuation of a resting membrane depolarization. Our data suggest that the depolarizing motor conduction failure in P0-/- could be acutely improved by C31. This provides proof-of-concept that treatment with oral subtype-selective NaV1.8 blockers could be used to improve the motor function in severe forms of demyelinating CMT.
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9
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Yin X, Kiryu-Seo S, Kidd GJ, Feltri ML, Wrabetz L, Trapp BD. Proteolipid protein cannot replace P0 protein as the major structural protein of peripheral nervous system myelin. Glia 2014; 63:66-77. [PMID: 25066805 DOI: 10.1002/glia.22733] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Accepted: 07/14/2014] [Indexed: 11/10/2022]
Abstract
The central nervous system (CNS) of terrestrial vertebrates underwent a prominent molecular change when proteolipid protein (PLP) replaced P0 protein as the most abundant protein of CNS myelin. However, PLP did not replace P0 in peripheral nervous system (PNS) myelin. To investigate the possible consequences of a PLP to P0 shift in PNS myelin, we engineered mice to express PLP instead of P0 in PNS myelin (PLP-PNS mice). PLP-PNS mice had severe neurological disabilities and died between 3 and 6 months of age. Schwann cells in sciatic nerves from PLP-PNS mice sorted axons into one-to-one relationships but failed to form myelin internodes. Mice with equal amounts of P0 and PLP had normal PNS myelination and lifespans similar to wild-type (WT) mice. When PLP was overexpressed with one copy of the P0 gene, sciatic nerves were hypomyelinated; mice displayed motor deficits, but had normal lifespans. These data support the hypothesis that while PLP can co-exist with P0 in PNS myelin, PLP cannot replace P0 as the major structural protein of PNS myelin.
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Affiliation(s)
- Xinghua Yin
- Department of Neurosciences, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
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10
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Alvarez S, Moldovan M, Krarup C. Prolonged high frequency electrical stimulation is lethal to motor axons of mice heterozygously deficient for the myelin protein P0 gene. Exp Neurol 2013; 247:552-61. [DOI: 10.1016/j.expneurol.2013.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 02/09/2013] [Accepted: 02/13/2013] [Indexed: 10/27/2022]
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11
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Functional recovery of regenerating motor axons is delayed in mice heterozygously deficient for the myelin protein P(0) gene. Neurochem Res 2013; 38:1266-77. [PMID: 23564290 DOI: 10.1007/s11064-013-1030-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Revised: 03/06/2013] [Accepted: 03/26/2013] [Indexed: 10/27/2022]
Abstract
Mice with a heterozygous knock-out of the myelin protein P0 gene (P0+/-) develop a neuropathy similar to human Charcot-Marie-Tooth disease. They are indistinguishable from wild-types (WT) at birth and develop a slowly progressing demyelinating neuropathy. The aim of this study was to investigate whether the regeneration capacity of early symptomatic P0+/- is impaired as compared to age matched WT. Right sciatic nerves were lesioned at the thigh in 7-8 months old mice. Tibial motor axons at ankle were investigated by conventional motor conduction studies and axon excitability studies using threshold tracking. To evaluate regeneration we monitored the recovery of motor function after crush, and then compared the fiber distribution by histology. The overall motor performance was investigated using Rotor-Rod. P0+/- had reduced compound motor action potential amplitudes and thinner myelinated axons with only a borderline impairment in conduction and Rotor-Rod. Plantar muscle reinnervation occurred within 21 days in all mice. Shortly after reinnervation the conduction of P0+/- regenerated axons was markedly slower than WT, however, this difference decayed with time. Nevertheless, after 1 month, regenerated P0+/- axons had longer strength-duration time constant, larger threshold changes during hyperpolarizing electrotonus and longer relative refractory period. Their performance at Rotor-Rod remained also markedly impaired. In contrast, the number and diameter distribution of regenerating myelinated fibers became similar to regenerated WT. Our data suggest that in the presence of heterozygously P0 deficient Schwann cells, regenerating motor axons retain their ability to reinnervate their targets and remyelinate, though their functional recovery is delayed.
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12
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Saporta MAC, Shy BR, Patzko A, Bai Y, Pennuto M, Ferri C, Tinelli E, Saveri P, Kirschner D, Crowther M, Southwood C, Wu X, Gow A, Feltri ML, Wrabetz L, Shy ME. MpzR98C arrests Schwann cell development in a mouse model of early-onset Charcot-Marie-Tooth disease type 1B. ACTA ACUST UNITED AC 2012; 135:2032-47. [PMID: 22689911 DOI: 10.1093/brain/aws140] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mutations in myelin protein zero (MPZ) cause Charcot-Marie-Tooth disease type 1B. Many dominant MPZ mutations, including R98C, present as infantile onset dysmyelinating neuropathies. We have generated an R98C 'knock-in' mouse model of Charcot-Marie-Tooth type 1B, where a mutation encoding R98C was targeted to the mouse Mpz gene. Both heterozygous (R98C/+) and homozygous (R98C/R98C) mice develop weakness, abnormal nerve conduction velocities and morphologically abnormal myelin; R98C/R98C mice are more severely affected. MpzR98C is retained in the endoplasmic reticulum of Schwann cells and provokes a transitory, canonical unfolded protein response. Ablation of Chop, a mediator of the protein kinase RNA-like endoplasmic reticulum kinase unfolded protein response pathway restores compound muscle action potential amplitudes of R98C/+ mice but does not alter the reduced conduction velocities, reduced axonal diameters or clinical behaviour of these animals. R98C/R98C Schwann cells are developmentally arrested in the promyelinating stage, whereas development is delayed in R98C/+ mice. The proportion of cells expressing c-Jun, an inhibitor of myelination, is elevated in mutant nerves, whereas the proportion of cells expressing the promyelinating transcription factor Krox-20 is decreased, particularly in R98C/R98C mice. Our results provide a potential link between the accumulation of MpzR98C in the endoplasmic reticulum and a developmental delay in myelination. These mice provide a model by which we can begin to understand the early onset dysmyelination seen in patients with R98C and similar mutations.
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Affiliation(s)
- Mario A C Saporta
- Department of Neurology, Wayne State University, Detroit, MI 48201, USA
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Moldovan M, Alvarez S, Pinchenko V, Klein D, Nielsen FC, Wood JN, Martini R, Krarup C. Na(v)1.8 channelopathy in mutant mice deficient for myelin protein zero is detrimental to motor axons. ACTA ACUST UNITED AC 2010; 134:585-601. [PMID: 21169333 DOI: 10.1093/brain/awq336] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Myelin protein zero mutations were found to produce Charcot-Marie-Tooth disease phenotypes with various degrees of myelin impairment and axonal loss, ranging from the mild 'demyelinating' adult form to severe and early onset forms. Protein zero deficient homozygous mice ( ) show a severe and progressive dysmyelinating neuropathy from birth with compromised myelin compaction, hypomyelination and distal axonal degeneration. A previous study using immunofluorescence showed that motor nerves deficient of myelin protein zero upregulate the Na(V)1.8 voltage gated sodium channel isoform, which is normally present only in restricted populations of sensory axons. The aim of this study was to investigate the function of motor axons in protein zero-deficient mice with particular emphasis on ectopic Na(V)1.8 voltage gated sodium channel. We combined 'threshold tracking' excitability studies with conventional nerve conduction studies, behavioural studies using rotor-rod measurements, and histological measures to assess membrane dysfunction and its progression in protein zero deficient homozygous mutants as compared with age-matched wild-type controls. The involvement of Na(V)1.8 was investigated by pharmacologic block using the subtype-selective Na(V)1.8 blocker A-803467 and chronically in Na(V)1.8 knock-outs. We found that in the context of dysmyelination, abnormal potassium ion currents and membrane depolarization, the ectopic Na(V)1.8 channels further impair the motor axon excitability in protein zero deficient homozygous mutants to an extent that precipitates conduction failure in severely affected axons. Our data suggest that a Na(V)1.8 channelopathy contributed to the poor motor function of protein zero deficient homozygous mutants, and that the conduction failure was associated with partially reversible reduction of the electrically evoked muscle response and of the clinical function as indicated by the partial recovery of function at rotor-rod measurements. As a consequence of these findings of partially reversible dysfunction, we propose that the Na(V)1.8 voltage gated sodium channel should be considered as a novel therapeutic target for Charcot-Marie-Tooth disease.
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Affiliation(s)
- Mihai Moldovan
- Institute of Neuroscience and Pharmacology, Panum, University of Copenhagen, Denmark
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Heinicke K, Baum O, Ogunshola OO, Vogel J, Stallmach T, Wolfer DP, Keller S, Weber K, Wagner PD, Gassmann M, Djonov V. Excessive erythrocytosis in adult mice overexpressing erythropoietin leads to hepatic, renal, neuronal, and muscular degeneration. Am J Physiol Regul Integr Comp Physiol 2006; 291:R947-56. [PMID: 16690772 DOI: 10.1152/ajpregu.00152.2006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To investigate the consequences of inborn excessive erythrocytosis, we made use of our transgenic mouse line (tg6) that constitutively overexpresses erythropoietin (Epo) in a hypoxia-independent manner, thereby reaching hematocrit levels of up to 0.89. We detected expression of human Epo in the brain and, to a lesser extent, in the lung but not in the heart, kidney, or liver of tg6 mice. Although no acute cardiovascular complications are observed, tg6 animals have a reduced lifespan. Decreased swim performance was observed in 5-mo-old tg6 mice. At about 7 mo, several tg6 animals developed spastic contractions of the hindlimbs followed by paralysis. Morphological analysis by light and electron microscopy showed degenerative processes in liver and kidney characterized by increased vascular permeability, chronic progressive inflammation, hemosiderin deposition, and general vasodilatation. Moreover, most of the animals showed severe nerve fiber degeneration of the sciatic nerve, decreased number of neuromuscular junctions, and degeneration of skeletal muscle fibers. Most probably, the developing demyelinating neuropathy resulted in muscular degeneration demonstrated in the extensor digitorum longus muscle. Taken together, chronically increased Epo levels inducing excessive erythrocytosis leads to multiple organ degeneration and reduced life expectancy. This model allows investigation of the impact of excessive erythrocytosis in individuals suffering from polycythemia vera, chronic mountain sickness, or in subjects tempted to abuse Epo by means of gene doping.
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Affiliation(s)
- Katja Heinicke
- Institute of Veterinary Physiology, Vetsuisse Faculty and Zurich Center for Integrative Human Physiology (ZIHP), Switzerland
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15
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Steck AJ, Erne B, Pareyson D, Sghirlanzoni A, Taroni F, Schaeren-Wiemers N. Normal expression of myelin protein zero with frame-shift mutation correlates with mild phenotype. J Peripher Nerv Syst 2006; 11:61-6. [PMID: 16519783 DOI: 10.1111/j.1085-9489.2006.00064.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mutations in the gene encoding for myelin protein zero (MPZ) cause inherited demyelinating peripheral neuropathies of different severity. The molecular and cellular mechanisms by which the MPZ mutations cause neuropathy are incompletely understood. We investigated MPZ, myelin basic protein, and peripheral myelin protein 22 (PMP22) protein expression levels in a nerve biopsy of a Charcot-Marie-Tooth type 1B patient heterozygous for the Val 102 frame-shift mutation. We demonstrate by quantitative immunohistochemical as well as by Western blot analyses that MPZ expression levels were not reduced in myelin membranes, a finding that is in accordance with the mild phenotype of this patient. Our data show that heterozygous 'loss-of-function' of MPZ may not necessarily lead to reduced protein levels. In conclusion, we demonstrate that careful analysis of protein expression levels in peripheral nerve tissues provides important information with respect to the understanding of the molecular basis of these neuropathies.
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Affiliation(s)
- Andreas J Steck
- Department of Research, University Hospital Basel, Pharmacenter, Basel, Switzerland.
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Berger P, Niemann A, Suter U. Schwann cells and the pathogenesis of inherited motor and sensory neuropathies (Charcot-Marie-Tooth disease). Glia 2006; 54:243-57. [PMID: 16856148 DOI: 10.1002/glia.20386] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Over the last 15 years, a number of mutations in a variety of genes have been identified that lead to inherited motor and sensory neuropathies (HMSN), also called Charcot-Marie-Tooth disease (CMT). In this review we will focus on the molecular and cellular mechanisms that cause the Schwann cell pathologies observed in dysmyelinating and demyelinating forms of CMT. In most instances, the underlying gene defects alter primarily myelinating Schwann cells followed by secondary axonal degeneration. The first set of proteins affected by disease-causing mutations includes the myelin components PMP22, P0/MPZ, Cx32/GJB1, and periaxin. A second group contains the regulators of myelin gene transcription EGR2/Krox20 and SOX10. A third group is composed of intracellular Schwann cells proteins that are likely to be involved in the synthesis, transport and degradation of myelin components. These include the myotubularin-related lipid phosphatase MTMR2 and its regulatory binding partner MTMR13/SBF2, SIMPLE, and potentially also dynamin 2. Mutations affecting the mitochondrial fission factor GDAP1 may indicate an important contribution of mitochondria in myelination or myelin maintenance, whereas the functions of other identified genes, including NDRG1, KIAA1985, and the tyrosyl-tRNA synthase YARS, are not yet clear. Mutations in GDAP1, YARS, and the pleckstrin homology domain of dynamin 2 lead to an intermediate form of CMT that is characterized by moderately reduced nerve conduction velocity consistent with minor myelin deficits. Whether these phenotypes originate in Schwann cells or in neurons, or whether both cell types are directly affected, remains a challenging question. However, based on the advances in systematic gene identification in CMT and the analyses of the function and dysfunction of the affected proteins, crucially interconnected pathways in Schwann cells in health and disease have started to emerge. These networks include the control of myelin formation and stability, membrane trafficking, intracellular protein sorting and quality control, and may extend to mitochondrial dynamics and basic protein biosynthesis.
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Affiliation(s)
- Philipp Berger
- Institute of Cell Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
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Rünker AE, Kobsar I, Fink T, Loers G, Tilling T, Putthoff P, Wessig C, Martini R, Schachner M. Pathology of a mouse mutation in peripheral myelin protein P0 is characteristic of a severe and early onset form of human Charcot-Marie-Tooth type 1B disorder. ACTA ACUST UNITED AC 2004; 165:565-73. [PMID: 15148307 PMCID: PMC2172360 DOI: 10.1083/jcb.200402087] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Mutations in the gene of the peripheral myelin protein zero (P0) give rise to the peripheral neuropathies Charcot-Marie-Tooth type 1B disease (CMT1B), Déjérine-Sottas syndrome, and congenital hypomyelinating neuropathy. To investigate the pathomechanisms of a specific point mutation in the P0 gene, we generated two independent transgenic mouse lines expressing the pathogenic CMT1B missense mutation Ile106Leu (P0sub) under the control of the P0 promoter on a wild-type background. Both P0sub-transgenic mouse lines showed shivering and ultrastructural abnormalities including retarded myelination, onion bulb formation, and dysmyelination seen as aberrantly folded myelin sheaths and tomacula in all nerve fibers. Functionally, the mutation leads to dispersed compound muscle action potentials and severely reduced conduction velocities. Our observations support the view that the Ile106Leu mutation acts by a dominant-negative gain of function and that the P0sub-transgenic mouse represents an animal model for a severe, tomaculous form of CMT1B.
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Affiliation(s)
- Annette E Rünker
- Center for Molecular Neurobiology, University of Hamburg, D-20246 Hamburg, Germany
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