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Echaniz-Laguna A, Cauquil C, Chanson JB, Tard C, Guyant-Marechal L, Kuntzer T, Ion IM, Lia AS, Bouligand J, Poinsignon V. EGR2 gene-linked hereditary neuropathies present with a bimodal age distribution at symptoms onset. J Peripher Nerv Syst 2023; 28:359-367. [PMID: 37306961 DOI: 10.1111/jns.12572] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 06/07/2023] [Accepted: 06/08/2023] [Indexed: 06/13/2023]
Abstract
BACKGROUND Mutations in the Early-Growth Response 2 (EGR2) gene cause various hereditary neuropathies, including demyelinating Charcot-Marie-Tooth (CMT) disease type 1D (CMT1D), congenital hypomyelinating neuropathy type 1 (CHN1), Déjerine-Sottas syndrome (DSS), and axonal CMT (CMT2). METHODS In this study, we identified 14 patients with heterozygous EGR2 mutations diagnosed between 2000 and 2022. RESULTS Mean age was 44 years (15-70), 10 patients were female (71%), and mean disease duration was 28 years (1-56). Disease onset was before age 15 years in nine cases (64%), after age 35 years in four cases (28%), and one patient aged 26 years was asymptomatic (7%). All symptomatic patients had pes cavus and distal lower limbs weakness (100%). Distal lower limbs sensory symptoms were observed in 86% of cases, hand atrophy in 71%, and scoliosis in 21%. Nerve conduction studies showed a predominantly demyelinating sensorimotor neuropathy in all cases (100%), and five patients needed walking assistance after a mean disease duration of 50 years (47-56) (36%). Three patients were misdiagnosed as inflammatory neuropathy and treated with immunosuppressive drugs for years before diagnosis was corrected. Two patients presented with an additional neurologic disorder, including Steinert's myotonic dystrophy and spinocerebellar ataxia (14%). Eight EGR2 gene mutations were found, including four previously undescribed. INTERPRETATION Our findings demonstrate EGR2 gene-related hereditary neuropathies are rare and slowly progressive demyelinating neuropathies with two major clinical presentations, including a childhood-onset variant and an adult-onset variant which may mimic inflammatory neuropathy. Our study also expands the genotypic spectrum of EGR2 gene mutations.
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Affiliation(s)
- Andoni Echaniz-Laguna
- Neurology Department, APHP, CHU de Bicêtre, Le Kremlin-Bicêtre, France
- French National Reference Centre for Rare Neuropathies (CERAMIC), Le Kremlin-Bicêtre, France
- INSERM U1195, Paris-Saclay University, Le Kremlin-Bicêtre, France
| | - Cécile Cauquil
- Neurology Department, APHP, CHU de Bicêtre, Le Kremlin-Bicêtre, France
- French National Reference Centre for Rare Neuropathies (CERAMIC), Le Kremlin-Bicêtre, France
| | - Jean-Baptiste Chanson
- Department of Neurology and Nord/Est/Ile de France Neuromuscular Reference Center, Hôpitaux Universitaires de Strasbourg, Strasbourg, France
| | - Céline Tard
- U1172, Department of Neurology, CHU de Lille, Centre de référence des maladies neuromusculaires Nord/Est/Ile-de-France, Lille, France
| | | | - Thierry Kuntzer
- Nerve-Muscle unit, Department of Clinical Neurosciences, Lausanne University Hospital (CHUV) and University of Lausanne, Lausanne, Switzerland
| | | | - Anne-Sophie Lia
- Centre Hospitalo-Universitaire (CHU) Limoges, Service de Biochimie et de Génétique Moléculaire, Limoges, France
| | - Jérôme Bouligand
- Department of Molecular Genetics Pharmacogenomics and Hormonology, APHP, CHU de Bicêtre, Le Kremlin-Bicêtre, France
| | - Vianney Poinsignon
- Department of Molecular Genetics Pharmacogenomics and Hormonology, APHP, CHU de Bicêtre, Le Kremlin-Bicêtre, France
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Han L, Huang Y, Nie Y, Li J, Chen G, Tu S, Shen P, Chen C. A novel PMP22 insertion mutation causing Charcot-Marie-Tooth disease type 3: A case report. Medicine (Baltimore) 2021; 100:e25163. [PMID: 33726003 PMCID: PMC7982204 DOI: 10.1097/md.0000000000025163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 02/25/2021] [Indexed: 01/05/2023] Open
Abstract
RATIONALE Charcot-Marie-Tooth disease (CMT) is a group of hereditary neuropathies with clinical features of muscle atrophy, sensory loss, and foot deformities. CMT is related to a number of genes, such as peripheral myelin protein 22 gene (PMP22). Missense mutations, small deletion mutations, and duplications of PMP22 are common in CMT patients, but few insertion mutation cases of PMP22 have been reported. PATIENT CONCERNS A 26-year-old male patient with the complaint of general weakness, peroneal atrophy, and deformities in the extremities visited our hospital. The patient was born with bilateral thumbs and feet dystonia. Additionally, delayed feet arch development and delayed walking was observed when he was a child. DIAGNOSIS Using whole-exome sequencing and electrophysiological test, we identified a novel insertion mutation of PMP22 (NM_153322, c.54_55insGTGCTG, p.(L19delinsVLL)) in a 26-year-old male patient with peroneal atrophy and nerve conduction was not elicited in electromyography (EMG) study. The Protein Variation Effect Analyzer (PROVEAN) program analysis predicted that the variant is likely to be "deleterious." SWISS-MODEL program predicted that alpha helix in original location was disrupted by inserted 6 bases, which may account for the occurrence of CMT3. INTERVENTIONS The patient received symptomatic and supportive treatments, and routine rehabilitation exercises during hospitalization. OUTCOMES The condition of the patient was improved, but the disease could not be cured. At 1- and 3-months follow-up, manifestations of the patient were unchanged, and he could take care of himself. LESSONS Our findings link a novel PMP22 mutation with a clinical diagnosis of CMT3. The link between gene variation and CMT phenotype may help to reveal the structure and function of PMP22 protein and the pathogenesis of CMT. This study adds further support to the heterogeneity of PMP22 related CMT and provides solid functional evidence for the pathogenicity of the p.(L19delinsVLL) PMP22 variant. Moreover, with the development of high-throughput sequencing technology, the combination of next-generation sequencing (NGS) and conventional Sanger sequencing is becoming one of the comprehensive, inexpensive, and convenient tools for genetic diagnosis of CMT.
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Affiliation(s)
- Liang Han
- Department of Integrated Traditional Chinese and Western Medicine, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan
| | - Yanjing Huang
- Department of Integrated Traditional Chinese and Western Medicine, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan
| | - Yuan Nie
- Rehabilitation Center, Qijiang District Hospital of Traditional Chinese Medicine, 50 Dashi Road of Wenlong Avenue, Chongqing
| | - Jing Li
- Department of Integrated Traditional Chinese and Western Medicine, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan
| | - Gang Chen
- Department of Integrated Traditional Chinese and Western Medicine, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan
| | - Shenghao Tu
- Department of Integrated Traditional Chinese and Western Medicine, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan
| | - Pan Shen
- Department of Integrated Traditional Chinese and Western Medicine, Tongji hospital, Tongji Medical College, Huazhong University of Science and Technology, 1095 Jiefang Avenue, Wuhan
| | - Chao Chen
- Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, China
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Moss KR, Bopp TS, Johnson AE, Höke A. New evidence for secondary axonal degeneration in demyelinating neuropathies. Neurosci Lett 2021; 744:135595. [PMID: 33359733 PMCID: PMC7852893 DOI: 10.1016/j.neulet.2020.135595] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 10/31/2020] [Accepted: 12/19/2020] [Indexed: 12/28/2022]
Abstract
Development of peripheral nervous system (PNS) myelin involves a coordinated series of events between growing axons and the Schwann cell (SC) progenitors that will eventually ensheath them. Myelin sheaths have evolved out of necessity to maintain rapid impulse propagation while accounting for body space constraints. However, myelinating SCs perform additional critical functions that are required to preserve axonal integrity including mitigating energy consumption by establishing the nodal architecture, regulating axon caliber by organizing axonal cytoskeleton networks, providing trophic and potentially metabolic support, possibly supplying genetic translation materials and protecting axons from toxic insults. The intermediate steps between the loss of these functions and the initiation of axon degeneration are unknown but the importance of these processes provides insightful clues. Prevalent demyelinating diseases of the PNS include the inherited neuropathies Charcot-Marie-Tooth Disease, Type 1 (CMT1) and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) and the inflammatory diseases Acute Inflammatory Demyelinating Polyneuropathy (AIDP) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Secondary axon degeneration is a common feature of demyelinating neuropathies and this process is often correlated with clinical deficits and long-lasting disability in patients. There is abundant electrophysiological and histological evidence for secondary axon degeneration in patients and rodent models of PNS demyelinating diseases. Fully understanding the involvement of secondary axon degeneration in these diseases is essential for expanding our knowledge of disease pathogenesis and prognosis, which will be essential for developing novel therapeutic strategies.
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Affiliation(s)
- Kathryn R Moss
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Taylor S Bopp
- Department of Neurology, Neuromuscular Division, Johns Hopkins School of Medicine, Baltimore, MD, United States
| | - Anna E Johnson
- 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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A de novo EGR2 variant, c.1232A > G p.Asp411Gly, causes severe early-onset Charcot-Marie-Tooth Neuropathy Type 3 (Dejerine-Sottas Neuropathy). Sci Rep 2019; 9:19336. [PMID: 31852952 PMCID: PMC6920433 DOI: 10.1038/s41598-019-55875-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Accepted: 12/03/2019] [Indexed: 01/04/2023] Open
Abstract
EGR2 (early growth response 2) is a crucial transcription factor for the myelination of the peripheral nervous system. Mutations in EGR2 are reported to cause a heterogenous spectrum of peripheral neuropathy with wide variation in both severity and age of onset, including demyelinating and axonal forms of Charcot-Marie Tooth (CMT) neuropathy, Dejerine-Sottas neuropathy (DSN/CMT3), and congenital hypomyelinating neuropathy (CHN/CMT4E). Here we report a sporadic de novo EGR2 variant, c.1232A > G (NM_000399.5), causing a missense p.Asp411Gly substitution and discovered through whole-exome sequencing (WES) of the proband. The resultant phenotype is severe demyelinating DSN with onset at two years of age, confirmed through nerve biopsy and electrophysiological examination. In silico analyses showed that the Asp411 residue is evolutionarily conserved, and the p.Asp411Gly variant was predicted to be deleterious by multiple in silico analyses. A luciferase-based reporter assay confirmed the reduced ability of p.Asp411Gly EGR2 to activate a PMP22 (peripheral myelin protein 22) enhancer element compared to wild-type EGR2. This study adds further support to the heterogeneity of EGR2-related peripheral neuropathies and provides strong functional evidence for the pathogenicity of the p.Asp411Gly EGR2 variant.
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Murakami T, Sunada Y. Schwann Cell and the Pathogenesis of Charcot–Marie–Tooth Disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:301-321. [DOI: 10.1007/978-981-32-9636-7_19] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Martinez-Moreno M, O'Shea TM, Zepecki JP, Olaru A, Ness JK, Langer R, Tapinos N. Regulation of Peripheral Myelination through Transcriptional Buffering of Egr2 by an Antisense Long Non-coding RNA. Cell Rep 2017; 20:1950-1963. [PMID: 28834756 PMCID: PMC5800313 DOI: 10.1016/j.celrep.2017.07.068] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Revised: 04/25/2017] [Accepted: 07/24/2017] [Indexed: 10/24/2022] Open
Abstract
Precise regulation of Egr2 transcription is fundamentally important to the control of peripheral myelination. Here, we describe a long non-coding RNA antisense to the promoter of Egr2 (Egr2-AS-RNA). During peripheral nerve injury, the expression of Egr2-AS-RNA is increased and correlates with decreased Egr2 transcript and protein levels. Ectopic expression of Egr2-AS-RNA in dorsal root ganglion (DRG) cultures inhibits the expression of Egr2 mRNA and induces demyelination. In vivo inhibition of Egr2-AS-RNA using oligonucleotide GapMers released from a biodegradable hydrogel following sciatic nerve injury reverts the EGR2-mediated gene expression profile and significantly delays demyelination. Egr2-AS-RNA gradually recruits H3K27ME3, AGO1, AGO2, and EZH2 on the Egr2 promoter following sciatic nerve injury. Furthermore, expression of Egr2-AS-RNA is regulated through ERK1/2 signaling to YY1, while loss of Ser184 of YY1 regulates binding to Egr2-AS-RNA. In conclusion, we describe functional exploration of an antisense long non-coding RNA in peripheral nervous system (PNS) biology.
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Affiliation(s)
- Margot Martinez-Moreno
- Molecular Neuroscience and Neuro-Oncology Laboratory, Geisinger Clinic, Danville, PA 17822, USA
| | - Timothy Mark O'Shea
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - John P Zepecki
- Molecular Neuroscience and Neuro-Oncology Laboratory, Geisinger Clinic, Danville, PA 17822, USA
| | - Alexander Olaru
- Molecular Neuroscience and Neuro-Oncology Laboratory, Geisinger Clinic, Danville, PA 17822, USA
| | - Jennifer K Ness
- Molecular Neuroscience and Neuro-Oncology Laboratory, Geisinger Clinic, Danville, PA 17822, USA
| | - Robert Langer
- David H. Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Harvard-Massachusetts Institute of Technology Division of Health Sciences and Technology, Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Nikos Tapinos
- Molecular Neuroscience and Neuro-Oncology Laboratory, Geisinger Clinic, Danville, PA 17822, USA.
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7
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EGR2 mutation enhances phenotype spectrum of Dejerine–Sottas syndrome. J Neurol 2016; 263:1456-8. [DOI: 10.1007/s00415-016-8153-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 10/21/2022]
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8
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Abstract
Tissue engineering of Schwann cells (SCs) can serve a number of purposes, such as in vitro SC-related disease modeling, treatment of peripheral nerve diseases or peripheral nerve injury, and, potentially, treatment of CNS diseases. SCs can be generated from autologous stem cells in vitro by recapitulating the various stages of in vivo neural crest formation and SC differentiation. In this review, we survey the cellular and molecular mechanisms underlying these in vivo processes. We then focus on the current in vitro strategies for generating SCs from two sources of pluripotent stem cells, namely embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). Different methods for SC engineering from ESCs and iPSCs are reviewed and suggestions are proposed for optimizing the existing protocols. Potential safety issues regarding the clinical application of iPSC-derived SCs are discussed as well. Lastly, we will address future aspects of SC engineering.
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9
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Lin HP, Oksuz I, Hurley E, Wrabetz L, Awatramani R. Microprocessor complex subunit DiGeorge syndrome critical region gene 8 (Dgcr8) is required for schwann cell myelination and myelin maintenance. J Biol Chem 2015; 290:24294-307. [PMID: 26272614 DOI: 10.1074/jbc.m115.636407] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Indexed: 01/25/2023] Open
Abstract
We investigated the role of a key component of the Microprocessor complex, DGCR8, in the regulation of myelin formation and maintenance. We found that conditionally ablating Dgcr8 in Schwann cells (SCs) during development results in an arrest of SC differentiation. Dgcr8 conditional knock-out (cKO) SCs fail to form 1:1 relationships with axons or, having achieved this, fail to form myelin sheaths. The expression of genes normally found in immature SCs, such as sex-determining region Y-box 2 (Sox2), is increased in Dgcr8 cKO SCs, whereas the expression of myelin-related genes, including the master regulatory transcription factor early growth response 2 (Egr2), is decreased. Additionally, expression of a novel gene expression program involving sonic hedgehog (Shh), activated de novo in injured nerves, is elevated in Dgcr8 cKOs but not in Egr2 null mice, a model of SC differentiation arrest, suggesting that the injury-related gene expression program in Dgcr8 cKOs cannot be attributed to differentiation arrest. Inducible ablation of Dgcr8 in adult SCs results in gene expression changes similar to those found in cKOs, including an increase in the expression of Sox2 and Shh. Analyses of these nerves mainly reveal normal myelin thickness and axon size distribution but some dedifferentiated SCs and increased macrophage infiltration. Together our data suggest that Dgcr8 is responsible for modulation of gene expression programs underlying myelin formation and maintenance as well as suppression of an injury-related gene expression program.
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Affiliation(s)
- Hsin-Pin Lin
- From the Department of Neurology and Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611 and
| | - Idil Oksuz
- From the Department of Neurology and Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611 and
| | - Edward Hurley
- Hunter James Kelly Research Institute, University at Buffalo, State University of New York, Buffalo, New York 14203
| | - Lawrence Wrabetz
- Hunter James Kelly Research Institute, University at Buffalo, State University of New York, Buffalo, New York 14203
| | - Rajeshwar Awatramani
- From the Department of Neurology and Center for Genetic Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611 and
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10
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Sevilla T, Sivera R, Martínez-Rubio D, Lupo V, Chumillas MJ, Calpena E, Dopazo J, Vílchez JJ, Palau F, Espinós C. TheEGR2gene is involved in axonal Charcot−Marie−Tooth disease. Eur J Neurol 2015. [DOI: 10.1111/ene.12782] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- T. Sevilla
- Department of Neurology; Hospital Universitari i Politècnic La Fe; Valencia Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Department of Medicine; University of Valencia; Valencia Spain
| | - R. Sivera
- Department of Neurology; Hospital Universitari i Politècnic La Fe; Valencia Spain
| | - D. Martínez-Rubio
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Program in Genetics and Rare Diseases and IBV/CSIC Associated Unit; Centro de Investigación Príncipe Felipe (CIPF); Valencia Spain
| | - V. Lupo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Program in Genetics and Rare Diseases and IBV/CSIC Associated Unit; Centro de Investigación Príncipe Felipe (CIPF); Valencia Spain
| | - M. J. Chumillas
- Department of Clinical Neurophysiology; Hospital Universitari i Politècnic La Fe; Valencia Spain
| | - E. Calpena
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Program in Genetics and Rare Diseases and IBV/CSIC Associated Unit; Centro de Investigación Príncipe Felipe (CIPF); Valencia Spain
| | - J. Dopazo
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Program in Computational Genomics; Centro de Investigación Príncipe Felipe (CIPF); Valencia Spain
| | - J. J. Vílchez
- Department of Neurology; Hospital Universitari i Politècnic La Fe; Valencia Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Department of Medicine; University of Valencia; Valencia Spain
| | - F. Palau
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Program in Genetics and Rare Diseases and IBV/CSIC Associated Unit; Centro de Investigación Príncipe Felipe (CIPF); Valencia Spain
| | - C. Espinós
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER); Valencia Spain
- Program in Genetics and Rare Diseases and IBV/CSIC Associated Unit; Centro de Investigación Príncipe Felipe (CIPF); Valencia Spain
- Department of Genetics; Universitat de València; Valencia Spain
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Odelin G, Faure E, Kober F, Maurel-Zaffran C, Théron A, Coulpier F, Guillet B, Bernard M, Avierinos JF, Charnay P, Topilko P, Zaffran S. Loss of Krox20 results in aortic valve regurgitation and impaired transcriptional activation of fibrillar collagen genes. Cardiovasc Res 2014; 104:443-55. [PMID: 25344368 DOI: 10.1093/cvr/cvu233] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
AIMS Heart valve maturation is achieved by the organization of extracellular matrix (ECM) and the distribution of valvular interstitial cells. However, the factors that regulate matrix components required for valvular structure and function are unknown. Based on the discovery of its specific expression in cardiac valves, we aimed to uncover the role of Krox20 (Egr-2) during valve development and disease. METHODS AND RESULTS Using series of mouse genetic tools, we demonstrated that loss of function of Krox20 caused significant hyperplasia of the semilunar valves, while atrioventricular valves appeared normal. This defect was associated with an increase in valvular interstitial cell number and ECM volume. Echo Doppler analysis revealed that adult mutant mice had aortic insufficiency. Defective aortic valves (AoVs) in Krox20(-/-) mice had features of human AoV disease, including excess of proteoglycan deposition and reduction of collagen fibres. Furthermore, examination of diseased human AoVs revealed decreased expression of KROX20. To identify downstream targets of Krox20, we examined expression of fibrillar collagens in the AoV leaflets at different stages in the mouse. We found significant down-regulation of Col1a1, Col1a2, and Col3a1 in the semilunar valves of Krox20 mutant mice. Utilizing in vitro and in vivo experiments, we demonstrated that Col1a1 and Col3a1 are direct targets of Krox20 activation in interstitial cells of the AoV. CONCLUSION This study identifies a previously unknown function of Krox20 during heart valve development. These results indicate that Krox20-mediated activation of fibrillar Col1a1 and Col3a1 genes is crucial to avoid postnatal degeneration of the AoV leaflets.
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Affiliation(s)
- Gaëlle Odelin
- Aix Marseille Université, GMGF UMR_S910, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France Inserm, U910, Faculté de Médecine, 27 Bd Jean Moulin, 13005 Marseille, France
| | - Emilie Faure
- Aix Marseille Université, GMGF UMR_S910, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France Inserm, U910, Faculté de Médecine, 27 Bd Jean Moulin, 13005 Marseille, France
| | - Frank Kober
- Faculté de Médecine, Aix Marseille Université, CNRS, CRMBM UMR7339, Marseille, France
| | | | - Alexis Théron
- Aix Marseille Université, GMGF UMR_S910, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France Inserm, U910, Faculté de Médecine, 27 Bd Jean Moulin, 13005 Marseille, France Département de Cardiologie, AP-HM, Hôpital de la Timone, Marseille, France
| | - Fanny Coulpier
- Inserm, U1024, IBENS, École Normale Supérieure, Paris, France CNRS, UMR8197, IBENS, École Normale Supérieure, Paris, France
| | - Benjamin Guillet
- Faculté de Médecine, Aix Marseille Université, CERIMED, Marseille, France
| | - Monique Bernard
- Faculté de Médecine, Aix Marseille Université, CNRS, CRMBM UMR7339, Marseille, France
| | - Jean-François Avierinos
- Aix Marseille Université, GMGF UMR_S910, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France Inserm, U910, Faculté de Médecine, 27 Bd Jean Moulin, 13005 Marseille, France Département de Cardiologie, AP-HM, Hôpital de la Timone, Marseille, France
| | - Patrick Charnay
- Inserm, U1024, IBENS, École Normale Supérieure, Paris, France CNRS, UMR8197, IBENS, École Normale Supérieure, Paris, France
| | - Piotr Topilko
- Inserm, U1024, IBENS, École Normale Supérieure, Paris, France CNRS, UMR8197, IBENS, École Normale Supérieure, Paris, France
| | - Stéphane Zaffran
- Aix Marseille Université, GMGF UMR_S910, Faculté de Médecine, 27 Bd Jean Moulin, 13385 Marseille, France Inserm, U910, Faculté de Médecine, 27 Bd Jean Moulin, 13005 Marseille, France
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12
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Tazir M, Bellatache M, Nouioua S, Vallat JM. Autosomal recessive Charcot-Marie-Tooth disease: from genes to phenotypes. J Peripher Nerv Syst 2013; 18:113-29. [DOI: 10.1111/jns5.12026] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 03/19/2013] [Accepted: 03/19/2013] [Indexed: 11/27/2022]
Affiliation(s)
- Meriem Tazir
- Service de Neurologie; University Hospital Mustapha Bacha; Alger Algeria
- Laboratoire de NeuroSciences; Université d'Alger 1; Alger Algeria
| | - Mounia Bellatache
- Service de Neurologie; University Hospital Mustapha Bacha; Alger Algeria
- Laboratoire de NeuroSciences; Université d'Alger 1; Alger Algeria
| | - Sonia Nouioua
- Service de Neurologie; University Hospital Mustapha Bacha; Alger Algeria
- Laboratoire de NeuroSciences; Université d'Alger 1; Alger Algeria
| | - Jean-Michel Vallat
- Centre de Référence ⟨Neuropathies Périphériques Rares⟩, Service et Laboratoire de Neurologie; University Hospital; Limoges France
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13
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Pareyson D, Marchesi C, Salsano E. Dominant Charcot-Marie-Tooth syndrome and cognate disorders. HANDBOOK OF CLINICAL NEUROLOGY 2013; 115:817-845. [PMID: 23931817 DOI: 10.1016/b978-0-444-52902-2.00047-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Charcot-Marie-Tooth neuropathy (CMT) is a group of genetically heterogeneous disorders sharing a similar phenotype, characterized by wasting and weakness mainly involving the distal muscles of lower and upper limbs, variably associated with distal sensory loss and skeletal deformities. This chapter deals with dominantly transmitted CMT and related disorders, namely hereditary neuropathy with liability to pressure palsies (HNPP) and hereditary neuralgic amyotrophy (HNA). During the last 20 years, several genes have been uncovered associated with CMT and our understanding of the underlying molecular mechanisms has greatly improved. Consequently, a precise genetic diagnosis is now possible in the majority of cases, thus allowing proper genetic counseling. Although, unfortunately, treatment is still unavailable for all types of CMT, several cellular and animal models have been developed and some compounds have proved effective in these models. The first trials with ascorbic acid in CMT type 1A have been completed and, although negative, are providing relevant information on disease course and on how to prepare for future trials.
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Affiliation(s)
- Davide Pareyson
- Clinics of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences, IRCCS Foundation, C. Besta Neurological Institute, Milan, Italy.
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Li J, Parker B, Martyn C, Natarajan C, Guo J. The PMP22 gene and its related diseases. Mol Neurobiol 2012; 47:673-98. [PMID: 23224996 DOI: 10.1007/s12035-012-8370-x] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
Abstract
Peripheral myelin protein-22 (PMP22) is primarily expressed in the compact myelin of the peripheral nervous system. Levels of PMP22 have to be tightly regulated since alterations of PMP22 levels by mutations of the PMP22 gene are responsible for >50 % of all patients with inherited peripheral neuropathies, including Charcot-Marie-Tooth type-1A (CMT1A) with trisomy of PMP22, hereditary neuropathy with liability to pressure palsies (HNPP) with heterozygous deletion of PMP22, and CMT1E with point mutations of PMP22. While overexpression and point-mutations of the PMP22 gene may produce gain-of-function phenotypes, deletion of PMP22 results in a loss-of-function phenotype that reveals the normal physiological functions of the PMP22 protein. In this article, we will review the basic genetics, biochemistry and molecular structure of PMP22, followed by discussion of the current understanding of pathogenic mechanisms involving in the inherited neuropathies with mutations in PMP22 gene.
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Affiliation(s)
- Jun Li
- VA Tennessee Valley Healthcare System, 1310 24th Avenue South, Nashville, TN 37212, USA.
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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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Houlden H, Reilly MM. Molecular genetics of autosomal-dominant demyelinating Charcot-Marie-Tooth disease. Neuromolecular Med 2012; 8:43-62. [PMID: 16775366 DOI: 10.1385/nmm:8:1-2:43] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2005] [Revised: 12/15/2005] [Accepted: 01/11/2006] [Indexed: 12/20/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) is a clinically and genetically heterogeneous group of disorders and is the most common inherited neuromuscular disorder, with an estimated overall prevalence of 17-40/10,000. Although there has been major advances in the understanding of the genetic basis of CMT in recent years, the most useful classification is still a neurophysiological classification that divides CMT into type 1 (demyelinating; median motor conduction velocity < 38 m/s) and type 2 (axonal; median motor conduction velocity > 38 m/s). An intermediate type is also increasingly being described. Inheritance can be autosomal-dominant (AD), X-linked, or autosomal-recessive (AR). AD CMT1 is the most common type of CMT and was the first form of CMT in which a causative gene was described. This review provides an up-to-date overview of AD CMT1 concentrating on the molecular genetics as the clinical, neurophysiological, and pathological features have been covered elsewhere. Four genes (PMP22, MPZ, LITAF, and EGR2) have been described in the last 15 yr associated with AD CMTI and a further gene (NEFL), originally described as causing AD CMT2 can also cause AD CMT1 (by neurophysiological criteria). Studies have shown many of these genes, when mutated, can cause a wide range of CMT phenotypes from the relatively mild CMT1 to the more severe Dejerine-Sottas disease and congenital hypomyelinating neuropathy, and even in some cases axonal CMT2. This review discusses what is known about these genes and in particular how they cause a peripheral neuropathy, when mutated.
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Affiliation(s)
- Henry Houlden
- Centre for Neuromuscular Disease and Department of Molecular Neurosciences, National Hospital for Neurology and Neurosurgery and Institute of Neurology, Queen Square, London, WC1N 3BG, UK
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Srinivasan R, Sun G, Keles S, Jones EA, Jang SW, Krueger C, Moran JJ, Svaren J. Genome-wide analysis of EGR2/SOX10 binding in myelinating peripheral nerve. Nucleic Acids Res 2012; 40:6449-60. [PMID: 22492709 PMCID: PMC3413122 DOI: 10.1093/nar/gks313] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 03/25/2012] [Accepted: 03/26/2012] [Indexed: 11/17/2022] Open
Abstract
Myelin is essential for the rapidity of saltatory nerve conduction, and also provides trophic support for axons to prevent axonal degeneration. Two critical determinants of myelination are SOX10 and EGR2/KROX20. SOX10 is required for specification of Schwann cells from neural crest, and is required at every stage of Schwann cell development. Egr2/Krox20 expression is activated by axonal signals in myelinating Schwann cells, and is required for cell cycle arrest and myelin formation. To elucidate the integrated function of these two transcription factors during peripheral nerve myelination, we performed in vivo ChIP-Seq analysis of myelinating peripheral nerve. Integration of these binding data with loss-of-function array data identified a range of genes regulated by these factors. In addition, although SOX10 itself regulates Egr2/Krox20 expression, leading to coordinate activation of several major myelin genes by the two factors, there is a large subset of genes that are activated independent of EGR2. Finally, the results identify a set of SOX10-dependent genes that are expressed in early Schwann cell development, but become subsequently repressed by EGR2/KROX20.
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Affiliation(s)
- Rajini Srinivasan
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Guannan Sun
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Sunduz Keles
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Erin A. Jones
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Sung-Wook Jang
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Courtney Krueger
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - John J. Moran
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - John Svaren
- Waisman Center, Department of Statistics, Department of Biostatistics and Medical Informatics, Program in Cellular and Molecular Biology and, Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
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Murphy SM, Laura M, Fawcett K, Pandraud A, Liu YT, Davidson GL, Rossor AM, Polke JM, Castleman V, Manji H, Lunn MPT, Bull K, Ramdharry G, Davis M, Blake JC, Houlden H, Reilly MM. Charcot-Marie-Tooth disease: frequency of genetic subtypes and guidelines for genetic testing. J Neurol Neurosurg Psychiatry 2012; 83:706-10. [PMID: 22577229 PMCID: PMC3736805 DOI: 10.1136/jnnp-2012-302451] [Citation(s) in RCA: 258] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Charcot-Marie-Tooth disease (CMT) is a clinically and genetically heterogeneous group of diseases with approximately 45 different causative genes described. The aims of this study were to determine the frequency of different genes in a large cohort of patients with CMT and devise guidelines for genetic testing in practice. METHODS The genes known to cause CMT were sequenced in 1607 patients with CMT (425 patients attending an inherited neuropathy clinic and 1182 patients whose DNA was sent to the authors for genetic testing) to determine the proportion of different subtypes in a UK population. RESULTS A molecular diagnosis was achieved in 62.6% of patients with CMT attending the inherited neuropathy clinic; in 80.4% of patients with CMT1 (demyelinating CMT) and in 25.2% of those with CMT2 (axonal CMT). Mutations or rearrangements in PMP22, GJB1, MPZ and MFN2 accounted for over 90% of the molecular diagnoses while mutations in all other genes tested were rare. CONCLUSION Four commonly available genes account for over 90% of all CMT molecular diagnoses; a diagnostic algorithm is proposed based on these results for use in clinical practice. Any patient with CMT without a mutation in these four genes or with an unusual phenotype should be considered for referral for an expert opinion to maximise the chance of reaching a molecular diagnosis.
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Affiliation(s)
- Sinead M Murphy
- MRC Centre for Neuromuscular Disease, National Hospital for Neurology and Neurosurgery, London WC1N 3BG, UK
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Safka Brožková D, Nevšímalová S, Mazanec R, Rautenstrauss B, Seeman P. Charcot-Marie-Tooth neuropathy due to a novel EGR2 gene mutation with mild phenotype--usefulness of human mapping chip linkage analysis in a Czech family. Neuromuscul Disord 2012; 22:742-6. [PMID: 22546699 DOI: 10.1016/j.nmd.2012.04.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 03/28/2012] [Accepted: 04/02/2012] [Indexed: 11/19/2022]
Abstract
Charcot-Marie-Tooth neuropathies (CMT) are a group of clinically and genetically heterogeneous disorders of the peripheral nervous system. Selection of candidate disease genes for mutation analysis is sometimes difficult since more than 40 genes and loci are known to be associated with CMT neuropathies. Hence a Czech family Cz-CMT with demyelinating type of autosomal dominant CMT disease was investigated by genome-wide linkage analysis by means of single-nucleotide polymorphism (SNP) arrays. Among 35 regions with linkage, five carried known CMT genes. In the final result a novel early growth response 2 - missense mutation c.1235 A>G, p.Glu412Gly was found. Surprisingly, the more severely affected proband carried an additional heterozygous myelin protein zero variant p.Asp246Asn detected previously, which may modify the phenotype. However, this MPZ variant is benign in heterozygous state alone, because it is also carried by the patient's healthy father.
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Affiliation(s)
- Dana Safka Brožková
- DNA Laboratory, Department of Child Neurology, Charles University 2nd Medical School and University Hospital Motol, Prague, Czech Republic.
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20
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Funalot B, Topilko P, Arroyo MAR, Sefiani A, Hedley-Whyte ET, Yoldi ME, Richard L, Touraille E, Laurichesse M, Khalifa E, Chauzeix J, Ouedraogo A, Cros D, Magdelaine C, Sturtz FG, Urtizberea JA, Charnay P, Bragado FG, Vallat JM. Homozygous deletion of an EGR2 enhancer in congenital amyelinating neuropathy. Ann Neurol 2012; 71:719-23. [DOI: 10.1002/ana.23527] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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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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Bucci C, Bakke O, Progida C. Charcot-Marie-Tooth disease and intracellular traffic. Prog Neurobiol 2012; 99:191-225. [PMID: 22465036 PMCID: PMC3514635 DOI: 10.1016/j.pneurobio.2012.03.003] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 12/23/2011] [Accepted: 03/13/2012] [Indexed: 12/23/2022]
Abstract
Mutations of genes whose primary function is the regulation of membrane traffic are increasingly being identified as the underlying causes of various important human disorders. Intriguingly, mutations in ubiquitously expressed membrane traffic genes often lead to cell type- or organ-specific disorders. This is particularly true for neuronal diseases, identifying the nervous system as the most sensitive tissue to alterations of membrane traffic. Charcot-Marie-Tooth (CMT) disease is one of the most common inherited peripheral neuropathies. It is also known as hereditary motor and sensory neuropathy (HMSN), which comprises a group of disorders specifically affecting peripheral nerves. This peripheral neuropathy, highly heterogeneous both clinically and genetically, is characterized by a slowly progressive degeneration of the muscle of the foot, lower leg, hand and forearm, accompanied by sensory loss in the toes, fingers and limbs. More than 30 genes have been identified as targets of mutations that cause CMT neuropathy. A number of these genes encode proteins directly or indirectly involved in the regulation of intracellular traffic. Indeed, the list of genes linked to CMT disease includes genes important for vesicle formation, phosphoinositide metabolism, lysosomal degradation, mitochondrial fission and fusion, and also genes encoding endosomal and cytoskeletal proteins. This review focuses on the link between intracellular transport and CMT disease, highlighting the molecular mechanisms that underlie the different forms of this peripheral neuropathy and discussing the pathophysiological impact of membrane transport genetic defects as well as possible future ways to counteract these defects.
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Affiliation(s)
- Cecilia Bucci
- Department of Biological and Environmental Sciences and Technologies (DiSTeBA), University of Salento, Via Provinciale Monteroni, 73100 Lecce, Italy.
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23
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Vincristine exacerbates asymptomatic Charcot–Marie–Tooth disease with a novel EGR2 mutation. Neurogenetics 2012; 13:77-82. [DOI: 10.1007/s10048-012-0313-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 01/09/2012] [Indexed: 10/14/2022]
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Baets J, Deconinck T, De Vriendt E, Zimoń M, Yperzeele L, Van Hoorenbeeck K, Peeters K, Spiegel R, Parman Y, Ceulemans B, Van Bogaert P, Pou-Serradell A, Bernert G, Dinopoulos A, Auer-Grumbach M, Sallinen SL, Fabrizi GM, Pauly F, Van den Bergh P, Bilir B, Battaloglu E, Madrid RE, Kabzińska D, Kochanski A, Topaloglu H, Miller G, Jordanova A, Timmerman V, De Jonghe P. Genetic spectrum of hereditary neuropathies with onset in the first year of life. Brain 2011; 134:2664-76. [PMID: 21840889 PMCID: PMC3170533 DOI: 10.1093/brain/awr184] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Early onset hereditary motor and sensory neuropathies are rare disorders encompassing congenital hypomyelinating neuropathy with disease onset in the direct post-natal period and Dejerine–Sottas neuropathy starting in infancy. The clinical spectrum, however, reaches beyond the boundaries of these two historically defined disease entities. De novo dominant mutations in PMP22, MPZ and EGR2 are known to be a typical cause of very early onset hereditary neuropathies. In addition, mutations in several other dominant and recessive genes for Charcot–Marie–Tooth disease may lead to similar phenotypes. To estimate mutation frequencies and to gain detailed insights into the genetic and phenotypic heterogeneity of early onset hereditary neuropathies, we selected a heterogeneous cohort of 77 unrelated patients who presented with symptoms of peripheral neuropathy within the first year of life. The majority of these patients were isolated in their family. We performed systematic mutation screening by means of direct sequencing of the coding regions of 11 genes: MFN2, PMP22, MPZ, EGR2, GDAP1, NEFL, FGD4, MTMR2, PRX, SBF2 and SH3TC2. In addition, screening for the Charcot–Marie–Tooth type 1A duplication on chromosome 17p11.2-12 was performed. In 35 patients (45%), mutations were identified. Mutations in MPZ, PMP22 and EGR2 were found most frequently in patients presenting with early hypotonia and breathing difficulties. The recessive genes FGD4, PRX, MTMR2, SBF2, SH3TC2 and GDAP1 were mutated in patients presenting with early foot deformities and variable delay in motor milestones after an uneventful neonatal period. Several patients displaying congenital foot deformities but an otherwise normal early development carried the Charcot–Marie–Tooth type 1A duplication. This study clearly illustrates the genetic heterogeneity underlying hereditary neuropathies with infantile onset.
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Affiliation(s)
- Jonathan Baets
- Neurogenetics Group, VIB Department of Molecular Genetics, University of Antwerp, Universiteitsplein 1, B-2610 Antwerpen, Belgium
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Jang SW, Srinivasan R, Jones EA, Sun G, Keles S, Krueger C, Chang LW, Nagarajan R, Svaren J. Locus-wide identification of Egr2/Krox20 regulatory targets in myelin genes. J Neurochem 2010; 115:1409-20. [PMID: 21044070 PMCID: PMC3260055 DOI: 10.1111/j.1471-4159.2010.07045.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Myelination of peripheral nerves by Schwann cells depends upon a gene regulatory network controlled by early growth response Egr2/Krox20, which is specifically required for Schwann cells to initiate and maintain myelination. To elucidate the mechanism by which Egr2 regulates gene expression during myelination, we have performed chromatin immunoprecipitation analysis on myelinating rat sciatic nerve in vivo. The resulting samples were applied to a tiled microarray consisting of a broad spectrum of genes that are activated or repressed in Egr2-deficient mice. The results show extensive binding within myelin-associated genes, as well as some genes that become repressed in myelinating Schwann cells. Many of the Egr2 peaks coincide with regions of open chromatin, which is a marker of enhancer regions. In addition, further analysis showed that there is substantial colocalization of Egr2 binding with Sox10, a transcription factor required for Schwann cell specification and other stages of Schwann cell development. Finally, we have found that Egr2 binds to promoters of several lipid biosynthetic genes, which is consistent with their dramatic up-regulation during the formation of lipid-rich myelin. Overall, this analysis provides a locus-wide profile of Egr2 binding patterns in major myelin-associated genes using myelinating peripheral nerve.
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Affiliation(s)
- Sung-Wook Jang
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Erin A. Jones
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Guannan Sun
- Department of Statistics, Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA
| | - Sunduz Keles
- Department of Statistics, Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI, USA
| | - Courtney Krueger
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Li-Wei Chang
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO, USA
| | - Rakesh Nagarajan
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO, USA
| | - John Svaren
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
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Hossain S, Fragoso G, Mushynski WE, Almazan G. Regulation of peripheral myelination by Src-like kinases. Exp Neurol 2010; 226:47-57. [DOI: 10.1016/j.expneurol.2010.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2010] [Revised: 07/13/2010] [Accepted: 08/02/2010] [Indexed: 01/06/2023]
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27
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Keckarevic-Markovic M, Milic-Rasic V, Mladenovic J, Dackovic J, Kecmanovic M, Keckarevic D, Savic-Pavicevic D, Romac S. Mutational analysis of GJB1, MPZ, PMP22, EGR2, and LITAF/SIMPLE in Serbian Charcot-Marie-Tooth patients. J Peripher Nerv Syst 2009; 14:125-36. [PMID: 19691535 DOI: 10.1111/j.1529-8027.2009.00222.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We report the results of mutational analysis in the following genes: GJB1, MPZ, PMP22, EGR2, and LITAF/SIMPLE in 57 Charcot-Marie-Tooth (CMT) patients of Serbian origin without the PMP22 duplication. We found 10 different mutations in 14 CMT patients: 6 mutations in GJB1, 3 in MPZ, and 1 in PMP22. Five of six GJB1 mutations are reported for the first time, and the most frequent one appears to be a founder mutation in the Serbian population. No mutations were found in EGR2 or LITAF. Thus, GJB1 mutation analysis should be done in patients without the PMP22 duplication and male-to-male transmission of CMT.
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28
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Svaren J, Meijer D. The molecular machinery of myelin gene transcription in Schwann cells. Glia 2009; 56:1541-1551. [PMID: 18803322 DOI: 10.1002/glia.20767] [Citation(s) in RCA: 176] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
During late fetal life, Schwann cells in the peripheral nerves singled out by the larger axons will transit through a promyelinating stage before exiting the cell cycle and initiating myelin formation. A network of extra- and intracellular signaling pathways, regulating a transcriptional program of cell differentiation, governs this progression of cellular changes, culminating in a highly differentiated cell. In this review, we focus on the roles of a number of transcription factors not only in myelination, during normal development, but also in demyelination, following nerve trauma. These factors include specification factors involved in early development of Schwann cells from neural crest (Sox10) as well as factors specifically required for transitions into the promyelinating and myelinating stages (Oct6/Scip and Krox20/Egr2). From this description, we can glean the first, still very incomplete, contours of a gene regulatory network that governs myelination and demyelination during development and regeneration.
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Affiliation(s)
- John Svaren
- Department of Comparative Biosciences, School of Veterinary Medicine and Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, USA
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29
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Natural History and Treatment of Peripheral Inherited Neuropathies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 652:207-24. [DOI: 10.1007/978-90-481-2813-6_14] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
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30
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Mager GM, Ward RM, Srinivasan R, Jang SW, Wrabetz L, Svaren J. Active gene repression by the Egr2.NAB complex during peripheral nerve myelination. J Biol Chem 2008; 283:18187-97. [PMID: 18456662 PMCID: PMC2440619 DOI: 10.1074/jbc.m803330200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Indexed: 11/06/2022] Open
Abstract
The Egr2/Krox20 transactivator is required for activation of many myelin-associated genes during peripheral nerve myelination by Schwann cells. However, recent work has indicated that Egr2 not only activates genes required for peripheral nerve myelination but may also be involved in gene repression. The NAB (NGFI-A/Egr-binding) corepressors interact with Egr2 and are required for proper coordination of myelin formation. Therefore, NAB proteins could mediate repression of some Egr2 target genes, although direct repression by Egr2 or NAB proteins during myelination has not been demonstrated. To define the physiological role of NAB corepression in gene repression by Egr2, we tested whether the Egr2.NAB complex directly repressed specific target genes. A screen for NAB-regulated genes identified several (including Id2, Id4, and Rad) that declined during the course of peripheral nerve myelination. In vivo chromatin immunoprecipitation analysis of the myelinating sciatic nerve was used to show developmental association of both Egr2 and NAB2 on the Id2, Id4, and Rad promoters as they were repressed during the myelination process. In addition, NAB2 represses transcription by interaction with the chromodomain helicase DNA-binding protein 4 (CHD4) subunit of the nucleosome remodeling and deacetylase chromatin remodeling complex, and we demonstrate that CHD4 occupies NAB-repressed promoters in a developmentally regulated manner in vivo. These results illustrate a novel aspect of genetic regulation of peripheral nerve myelination by showing that Egr2 directly represses genes during myelination in conjunction with NAB corepressors. Furthermore, repression of Id2 was found to augment activation of Mpz (myelin protein zero) expression.
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Affiliation(s)
- Gennifer M Mager
- Molecular and Cellular Pharmacology Training Program, Department of Comparative Biosciences, Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, WI 53706, USA
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31
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Desmazières A, Decker L, Vallat JM, Charnay P, Gilardi-Hebenstreit P. Disruption of Krox20-Nab interaction in the mouse leads to peripheral neuropathy with biphasic evolution. J Neurosci 2008; 28:5891-900. [PMID: 18524893 PMCID: PMC6670318 DOI: 10.1523/jneurosci.5187-07.2008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2007] [Revised: 03/21/2008] [Accepted: 04/21/2008] [Indexed: 11/21/2022] Open
Abstract
Krox20/Egr2 is a zinc finger transcription factor that plays essential roles in several developmental processes, including peripheral nervous system myelination by Schwann cells, where it acts as a master gene regulator. Krox20 is known to interact with cofactors of the Nab family and a mutation affecting isoleucine 268, which prevents this interaction, has been shown to result in congenital hypomyelinating neuropathy in humans. To further investigate the role of this interaction, we have introduced such a mutation, Krox20(I268F), in the mouse germ line. Clinical, immunohistochemical, and ultrastructural analyses of the homozygous mutants reveal that they develop a severe hypomyelination phenotype that mimics the human syndrome. Furthermore, a time-course analysis of the disease indicates that it follows a biphasic evolution, the hypomyelination phase being followed by a dramatic demyelination. Although for the regulation of most analyzed Krox20 target genes the mutation behaves as a loss of function, this is not the case for a few of them. This differential effect indicates that the molecular function of the Krox20-Nab interaction is target dependent and might explain the degradation of the residual myelin, because of imbalances in its composition. In conclusion, this work provides a novel and useful model for severe human peripheral neuropathies.
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Affiliation(s)
- Anne Desmazières
- Inserm U784, 75230 Paris Cedex 05, France
- Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
| | - Laurence Decker
- Inserm U784, 75230 Paris Cedex 05, France
- Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
| | - Jean-Michel Vallat
- Laboratoire de Neurologie, Centre Hospitalier Universitaire Dupuytren, 87402 Limoges, France
| | - Patrick Charnay
- Inserm U784, 75230 Paris Cedex 05, France
- Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
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Magnaghi V, Ballabio M, Roglio I, Melcangi RC. Progesterone derivatives increase expression of Krox-20 and Sox-10 in rat Schwann cells. J Mol Neurosci 2008; 31:149-57. [PMID: 17478888 DOI: 10.1385/jmn/31:02:149] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2006] [Revised: 11/30/1999] [Accepted: 11/01/2006] [Indexed: 11/11/2022]
Abstract
Neuroactive steroids, like progesterone (P) and its 5alpha-reduced derivatives dihydroprogesterone (DHP) and tetrahydroprogesterone (THP), are involved in the control of Schwann cell proliferation and in the myelinating program of these cells. Here, we demonstrate that in culture of rat Schwann cells, P and its derivatives also increase expression of Sox-10 and Krox-20 (i.e., two transcription factors with a key role in Schwann cell physiology and in their myelinating program). Data obtained by quantitative RT-PCR analysis show that treatment with P, DHP, or THP increases mRNA levels of Krox-20. This stimulatory effect anticipates that exerted by P and DHP on Sox-10 gene expression. Thus, although the effect on Krox-20 occurs after 1 h, that on Sox-10 reaches a peak after 2 h. A similar pattern of effect is also evident on their protein levels. As evaluated by Western blot analysis, Krox-20 is increased after 3 h of treatment with P, DHP, or THP, whereas P or DHP stimulates the expression of Sox-10 after 6 h of exposure. A computer analysis performed on rat and human promoters of these two transcription factors shows that putative P-responsive elements are present in Krox-20 but not in Sox-10. Interestingly, many putative binding sites for Krox-20 are present in the Sox-10 promoter. The observations reported here, together with the concept that P and its derivatives are able to influence directly the expression of myelin proteins, suggest that these neuroactive steroids might coordinate the Schwann cell-myelinating program utilizing different intracellular pathways.
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Affiliation(s)
- Valerio Magnaghi
- Department of Endocrinology and Center of Excellence of Neurodegenerative Diseases, University of Milan, 20133 Milan, Italy
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Barisic N, Claeys KG, Sirotković-Skerlev M, Löfgren A, Nelis E, De Jonghe P, Timmerman V. Charcot-Marie-Tooth disease: a clinico-genetic confrontation. Ann Hum Genet 2008; 72:416-41. [PMID: 18215208 DOI: 10.1111/j.1469-1809.2007.00412.x] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) is the most common neuromuscular disorder. It represents a group of clinically and genetically heterogeneous inherited neuropathies. Here, we review the results of molecular genetic investigations and the clinical and neurophysiological features of the different CMT subtypes. The products of genes associated with CMT phenotypes are important for the neuronal structure maintenance, axonal transport, nerve signal transduction and functions related to the cellular integrity. Identifying the molecular basis of CMT and studying the relevant genes and their functions is important to understand the pathophysiological mechanisms of these neurodegenerative disorders, and the processes involved in the normal development and function of the peripheral nervous system. The results of molecular genetic investigations have impact on the appropriate diagnosis, genetic counselling and possible new therapeutic options for CMT patients.
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Affiliation(s)
- N Barisic
- Department of Pediatrics, Zagreb University Medical School, Zagreb, Croatia.
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Poirier R, Cheval H, Mailhes C, Charnay P, Davis S, Laroche S. Paradoxical role of an Egr transcription factor family member, Egr2/Krox20, in learning and memory. Front Behav Neurosci 2007; 1:6. [PMID: 18958188 PMCID: PMC2525857 DOI: 10.3389/neuro.08.006.2007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Accepted: 11/30/2007] [Indexed: 11/13/2022] Open
Abstract
It is well established that Egr1/zif268, a member of the Egr family of transcription factors, is critical for the consolidation of several forms of memories. Recently, the Egr3 family member has also been implicated in learning and memory. Because Egr family members encode closely related zinc-finger transcription factors sharing a highly homologous DNA binding domain that recognises the same DNA sequence, they may have related functions in brain. Another Egr family member expressed in brain, Egr2/Krox20 is known to be crucial for normal hindbrain development and has been implicated in several inherited peripheral neuropathies; however, due to Egr2-null mice perinatal lethality, its potential role in cognitive functions in the adult has not been yet explored. Here, we generated Egr2 conditional mutant mice allowing postnatal, forebrain-specific Cre-mediated Egr2 excision and tested homozygous, heterozygous and control littermates on a battery of behavioural tasks to evaluate motor capacity, exploratory behaviour, emotional reactivity and learning and memory performance in spatial and non-spatial tasks. Egr2-deficient mice had no sign of locomotor, exploratory or anxiety disturbances. Surprisingly, they also had no impairment in spatial learning and memory, taste aversion memory or fear memory using a trace conditioning paradigm. On the contrary, Egr2-deficient mice had improved performance in motor learning on a rotarod, and in object recognition memory. These results clearly do not extend the phenotypic consequences resulting from either Egr1 or Egr3 loss-of-function to Egr2. In contrast, they indicate that Egr family members may have different, and in certain circumstances antagonistic functions in the adult brain.
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Affiliation(s)
- Roseline Poirier
- Laboratoire de Neurobiologie de l'Apprentissage, Univ Paris Sud France. roseline.poirier@ u-psud.fr
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Srinivasan R, Jang SW, Ward RM, Sachdev S, Ezashi T, Svaren J. Differential regulation of NAB corepressor genes in Schwann cells. BMC Mol Biol 2007; 8:117. [PMID: 18096076 PMCID: PMC2235890 DOI: 10.1186/1471-2199-8-117] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 12/20/2007] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Myelination of peripheral nerves by Schwann cells requires not only the Egr2/Krox-20 transactivator, but also the NGFI-A/Egr-binding (NAB) corepressors, which modulate activity of Egr2. Previous work has shown that axon-dependent expression of Egr2 is mediated by neuregulin stimulation, and NAB corepressors are co-regulated with Egr2 expression in peripheral nerve development. NAB corepressors have also been implicated in macrophage development, cardiac hypertrophy, prostate carcinogenesis, and feedback regulation involved in hindbrain development. RESULTS To test the mechanism of NAB regulation in Schwann cells, transfection assays revealed that both Nab1 and Nab2 promoters are activated by Egr2 expression. Furthermore, direct binding of Egr2 at these promoters was demonstrated in vivo by chromatin immunoprecipitation analysis of myelinating sciatic nerve, and binding of Egr2 to the Nab2 promoter was stimulated by neuregulin in primary Schwann cells. Although Egr2 expression activates the Nab2 promoter more highly than Nab1, we surprisingly found that only Nab1 - but not Nab2 - expression levels were reduced in sciatic nerve from Egr2 null mice. Analysis of the Nab2 promoter showed that it is also activated by ETS proteins (Ets2 and Etv1/ER81) and is bound by Ets2 in vivo. CONCLUSION Overall, these results indicate that induction of Nab2 expression in Schwann cells involves not only Egr2, but also ETS proteins that are activated by neuregulin stimulation. Although Nab1 and Nab2 play partially redundant roles, regulation of Nab2 expression by ETS factors explains several observations regarding regulation of NAB genes. Finally, these data suggest that NAB proteins are not only feedback inhibitors of Egr2, but rather that co-induction of Egr2 and NAB genes is involved in forming an Egr2/NAB complex that is crucial for regulation of gene expression.
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Affiliation(s)
- Rajini Srinivasan
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Sung-Wook Jang
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI, USA
| | - Rebecca M Ward
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
| | - Shrikesh Sachdev
- Department of Biochemistry, University of Missouri-Columbia, Columbia, MO, USA
| | - Toshihiko Ezashi
- Department of Animal Sciences, University of Missouri-Columbia, Columbia, MO, USA
| | - John Svaren
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI, USA
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Abstract
PURPOSE OF REVIEW The purpose of this review is to help neurologists understand new concepts in hereditary neuropathies, from the clinician's point of view, in the molecular era after the burst of information regarding peripheral nerve biology. RECENT FINDINGS Recent studies have focused on understanding the pathomechanisms involved in hereditary neuropathies. In the past year identification of new genes has slowed down since scientists have concentrated more on the function of genes causing Charcot-Marie-Tooth disease and Schwann cell-axon interactions to reveal the molecular cell biology of the disease. Animal models for the most common subtypes of human Charcot-Marie-Tooth disease are now available. SUMMARY Rapid advances in the molecular genetics and cell biology of hereditary neuropathies have highlighted the great genetic complexity of Charcot-Marie-Tooth disease. The evolution from a simple clinical classification to a complex molecular one has not facilitated our understanding of the disease. Moreover, the new molecular classification is not simple to use as different mutations of the same gene produce a range of phenotypes. The clinicians have to look for specific clinical and electrophysiological clues to direct the patient to appropriate genetic testing.
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Affiliation(s)
- Yesim Parman
- Istanbul Faculty of Medicine, Neurology Department, Istanbul University, Istanbul, Turkey.
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Jones EA, Jang SW, Mager GM, Chang LW, Srinivasan R, Gokey NG, Ward RM, Nagarajan R, Svaren J. Interactions of Sox10 and Egr2 in myelin gene regulation. NEURON GLIA BIOLOGY 2007; 3:377-87. [PMID: 18634568 PMCID: PMC2605513 DOI: 10.1017/s1740925x08000173] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Myelination in the PNS is accompanied by a large induction of the myelin protein zero (Mpz) gene to produce the most abundant component in peripheral myelin. Analyses of knockout mice have shown that the EGR2/Krox20 and SOX10 transcription factors are required for Mpz expression. Our recent work has shown that the dominant EGR2 mutations associated with human peripheral neuropathies cause disruption of EGR2/SOX10 synergy at specific sites, including a conserved enhancer element in the first intron of the Mpz gene. Further investigation of Egr2/Sox10 interactions reveals that activation of the Mpz intron element by Egr2 requires both Sox10-binding sites. In addition, both Egr1 and Egr3 cooperate with Sox10 to activate this element, which indicates that this capacity is conserved among Egr family members. Finally, a conserved composite structure of Egr2/Sox10-binding sites in the genes encoding Mpz, myelin-associated glycoprotein and myelin basic protein genes was used to screen for similar modules in other myelin genes, revealing a potential regulatory element in the periaxin gene. Overall, these results elucidate a working model for developmental regulation of Mpz expression, several facets of which extend to regulation of other peripheral myelin genes.
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Affiliation(s)
- Erin A Jones
- Program in Cellular and Molecular Biology, University of Wisconsin-Madison, Madison, WI 53706, USA.
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Szigeti K, Wiszniewski W, Saifi GM, Sherman DL, Sule N, Adesina AM, Mancias P, Papasozomenos SC, Miller G, Keppen L, Daentl D, Brophy PJ, Lupski JR. Functional, histopathologic and natural history study of neuropathy associated with EGR2 mutations. Neurogenetics 2007; 8:257-62. [PMID: 17717711 DOI: 10.1007/s10048-007-0094-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 06/11/2007] [Indexed: 01/13/2023]
Abstract
Mutations in the EGR2 gene cause a spectrum of Charcot-Marie-Tooth disease and related inherited peripheral neuropathies. We ascertained ten consecutive patients with various EGR2 mutations, report a novel de novo mutation, and provide longitudinal clinical data to characterize the natural history of the peripheral neuropathy. We confirmed that respiratory compromise and cranial nerve dysfunction are commonly associated with EGR2 mutations and can be useful in guiding molecular diagnosis. We also contrast morphological studies in the context of the I268N homozygous recessive mutation affecting the NAB repressor binding site and the R359W dominant-negative mutation in the zinc-finger domain.
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Affiliation(s)
- Kinga Szigeti
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Rm 604B, Houston, TX 77030, USA
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Delague V, Jacquier A, Hamadouche T, Poitelon Y, Baudot C, Boccaccio I, Chouery E, Chaouch M, Kassouri N, Jabbour R, Grid D, Mégarbané A, Haase G, Lévy N. Mutations in FGD4 encoding the Rho GDP/GTP exchange factor FRABIN cause autosomal recessive Charcot-Marie-Tooth type 4H. Am J Hum Genet 2007; 81:1-16. [PMID: 17564959 PMCID: PMC1950914 DOI: 10.1086/518428] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2007] [Accepted: 03/15/2007] [Indexed: 12/11/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disorders are a clinically and genetically heterogeneous group of hereditary motor and sensory neuropathies characterized by muscle weakness and wasting, foot and hand deformities, and electrophysiological changes. The CMT4H subtype is an autosomal recessive demyelinating form of CMT that was recently mapped to a 15.8-Mb region at chromosome 12p11.21-q13.11, in two consanguineous families of Mediterranean origin, by homozygosity mapping. We report here the identification of mutations in FGD4, encoding FGD4 or FRABIN (FGD1-related F-actin binding protein), in both families. FRABIN is a GDP/GTP nucleotide exchange factor (GEF), specific to Cdc42, a member of the Rho family of small guanosine triphosphate (GTP)-binding proteins (Rho GTPases). Rho GTPases play a key role in regulating signal-transduction pathways in eukaryotes. In particular, they have a pivotal role in mediating actin cytoskeleton changes during cell migration, morphogenesis, polarization, and division. Consistent with these reported functions, expression of truncated FRABIN mutants in rat primary motoneurons and rat Schwann cells induced significantly fewer microspikes than expression of wild-type FRABIN. To our knowledge, this is the first report of mutations in a Rho GEF protein being involved in CMT.
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Affiliation(s)
- Valérie Delague
- INSERM U491, Génétique Médicale et Développement, Faculté de Médecine de la Timone, Marseille, France.
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Delague V, Jacquier A, Hamadouche T, Poitelon Y, Baudot C, Boccaccio I, Chouery E, Chaouch M, Kassouri N, Jabbour R, Grid D, Mégarbané A, Haase G, Lévy N. Mutations in FGD4 encoding the Rho GDP/GTP exchange factor FRABIN cause autosomal recessive Charcot-Marie-Tooth type 4H. Am J Hum Genet 2007. [PMID: 17564959 DOI: 10.1086/518428/s0002-9297(07)62812-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disorders are a clinically and genetically heterogeneous group of hereditary motor and sensory neuropathies characterized by muscle weakness and wasting, foot and hand deformities, and electrophysiological changes. The CMT4H subtype is an autosomal recessive demyelinating form of CMT that was recently mapped to a 15.8-Mb region at chromosome 12p11.21-q13.11, in two consanguineous families of Mediterranean origin, by homozygosity mapping. We report here the identification of mutations in FGD4, encoding FGD4 or FRABIN (FGD1-related F-actin binding protein), in both families. FRABIN is a GDP/GTP nucleotide exchange factor (GEF), specific to Cdc42, a member of the Rho family of small guanosine triphosphate (GTP)-binding proteins (Rho GTPases). Rho GTPases play a key role in regulating signal-transduction pathways in eukaryotes. In particular, they have a pivotal role in mediating actin cytoskeleton changes during cell migration, morphogenesis, polarization, and division. Consistent with these reported functions, expression of truncated FRABIN mutants in rat primary motoneurons and rat Schwann cells induced significantly fewer microspikes than expression of wild-type FRABIN. To our knowledge, this is the first report of mutations in a Rho GEF protein being involved in CMT.
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Affiliation(s)
- Valérie Delague
- INSERM U491, Génétique Médicale et Développement, Faculté de Médecine de la Timone, Marseille, France.
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LeBlanc SE, Ward RM, Svaren J. Neuropathy-associated Egr2 mutants disrupt cooperative activation of myelin protein zero by Egr2 and Sox10. Mol Cell Biol 2007; 27:3521-9. [PMID: 17325040 PMCID: PMC1899967 DOI: 10.1128/mcb.01689-06] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2006] [Revised: 10/17/2006] [Accepted: 02/13/2007] [Indexed: 12/25/2022] Open
Abstract
Dominant mutations in the early growth response 2 (Egr2/Krox20) transactivator, a critical regulator of peripheral myelin development, have been associated with peripheral myelinopathies. These dominant mutants interfere with the expression of genes required for myelination by Schwann cells, including that for the most abundant peripheral myelin protein, Myelin protein zero (Mpz). In this study, we show that Egr2 mutants specifically affect an Egr2-responsive element within the Mpz first intron that also contains binding sites for the transcription factor Sox10. Furthermore, Egr2 activation through this element is impaired by mutation of the Sox10 binding sites. Using chromatin immunoprecipitation assays, we found that Egr2 and Sox10 bind to this element in myelinating sciatic nerve and that a dominant Egr2 mutant does not perturb Egr2 binding but rather attenuates binding of Sox10 to the Mpz intron element. Sox10 binding at other sites of Egr2/Sox10 synergy, including a novel site in the Myelin-associated glycoprotein (Mag) gene, is also reduced by the dominant Egr2 mutant. These results provide the first demonstration of binding of Egr2/Sox10 to adjacent sites in vivo and also demonstrate that neuropathy-associated Egr2 mutants antagonize binding of Sox10 at specific sites, thereby disrupting genetic control of the myelination program.
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Ouvrier R, Geevasingha N, Ryan MM. Autosomal-recessive and X-linked forms of hereditary motor and sensory neuropathy in childhood. Muscle Nerve 2007; 36:131-43. [PMID: 17410579 DOI: 10.1002/mus.20776] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The hereditary motor and sensory neuropathies (HMSNs, Charcot-Marie-Tooth neuropathies) are the most common degenerative disorders of the peripheral nervous system. In recent years a dramatic expansion has occurred in our understanding of the molecular basis and cell biology of the recessively inherited demyelinating and axonal neuropathies, with delineation of a number of new neuropathies. Mutations in some genes cause a wide variety of clinical, neurophysiologic, and pathologic phenotypes, rendering diagnosis difficult. The X-linked forms of HMSN represent at least 10%-15% of all HMSNs and have an expanded disease spectrum including demyelinating, intermediate, and axonal neuropathies, transient central nervous system (CNS) dysfunction, mental retardation, and hearing loss. This review presents an overview of the recessive and X-linked forms of HMSN observed in childhood, with particular reference to disease phenotype and neurophysiologic and pathologic abnormalities suggestive of specific diagnoses. These findings can be used by the clinician to formulate a differential diagnosis and guide targeted genetic testing.
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Affiliation(s)
- Robert Ouvrier
- TY Nelson Department of Neurology and Neurosurgery, Children's Hospital at Westmead, Locked Bag 4001, Westmead, NSW 2145, Australia.
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Jang SW, LeBlanc SE, Roopra A, Wrabetz L, Svaren J. In vivo detection of Egr2 binding to target genes during peripheral nerve myelination. J Neurochem 2006; 98:1678-87. [PMID: 16923174 DOI: 10.1111/j.1471-4159.2006.04069.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Egr2/Krox20 is a zinc finger transactivator that regulates a diverse array of genes required for peripheral nerve myelination. Although several studies have elucidated the Egr2-regulated gene network, it is not clear if Egr2 regulates its target genes directly or indirectly through induction of other transactivators. Moreover, very few Egr2 binding sites have been identified in regulatory elements of myelin genes. To address this issue, we have successfully adapted chromatin immunoprecipitation assays to test if Egr2 binds directly to target genes in myelinating rat sciatic nerve. These experiments demonstrate direct binding of Egr2 to previously described binding sites within the Schwann cell enhancer of the myelin basic protein gene. Furthermore, we show Egr2 binding to a conserved site within the myelin-associated glycoprotein gene. Finally, our experiments provide the first evidence that Egr2 directly regulates expression of desert hedgehog, which is critically involved in development, maintenance and regeneration of multiple nerve elements including myelinated fibers. Surprisingly, this analysis has identified an apparent preponderance of Egr2 binding sites within conserved intron sequences of several myelin genes. Application of chromatin immunoprecipitation analysis to myelination in vivo will prove to be a valuable asset in assaying transcription factor binding and chromatin modifications during activation of myelin genes.
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Affiliation(s)
- Sung-Wook Jang
- Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin, USA
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Decker L, Desmarquet-Trin-Dinh C, Taillebourg E, Ghislain J, Vallat JM, Charnay P. Peripheral myelin maintenance is a dynamic process requiring constant Krox20 expression. J Neurosci 2006; 26:9771-9. [PMID: 16988048 PMCID: PMC6674452 DOI: 10.1523/jneurosci.0716-06.2006] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2006] [Revised: 07/04/2006] [Accepted: 08/03/2006] [Indexed: 01/13/2023] Open
Abstract
Onset of myelination in Schwann cells is governed by several transcription factors, including Krox20/Egr2, and mutations affecting Krox20 result in various human hereditary peripheral neuropathies, including congenital hypomyelinating neuropathy (CHN) and Charcot-Marie-Tooth disease (CMT). Similar molecular information is not available on the process of myelin maintenance. We have generated conditional Krox20 mutations in the mouse that allowed us to develop models for CHN and CMT. In the latter case, specific inactivation of Krox20 in adult Schwann cells results in severe demyelination, involving rapid Schwann cell dedifferentiation and increased proliferation, followed by an attempt to remyelinate and a block at the promyelinating stage. These data establish that Krox20 is not only required for the onset of myelination but that it is also crucial for the maintenance of the myelinating state. Furthermore, myelin maintenance appears as a very dynamic process in which Krox20 may constitute a molecular switch between Schwann cell myelination and demyelination programs.
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Affiliation(s)
- Laurence Decker
- Institut National de la Santé et de la Recherche Médicale, U784, Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
| | - Carole Desmarquet-Trin-Dinh
- Institut National de la Santé et de la Recherche Médicale, U784, Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
| | - Emmanuel Taillebourg
- Institut National de la Santé et de la Recherche Médicale, U784, Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
| | - Julien Ghislain
- Institut National de la Santé et de la Recherche Médicale, U784, Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
| | - Jean-Michel Vallat
- Laboratoire de Neurologie, Centre Hospitalier Universitaire Dupuytren, 87042 Limoges, France
| | - Patrick Charnay
- Institut National de la Santé et de la Recherche Médicale, U784, Ecole Normale Supérieure, 75230 Paris Cedex 05, France, and
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Abstract
Charcot-Marie-Tooth disease (CMT) is the most common form of inherited motor and sensory neuropathy. Moreover, CMT is a genetically heterogeneous disorder of the peripheral nervous system, with many genes identified as CMT-causative. CMT has two usual classifications: type 1, the demyelinating form (CMT1); and type 2, the axonal form (CMT2). In addition, patients are classified as CMTX if they have an X-linked inheritance pattern and CMT4 if the inheritance pattern is autosomal recessive. A large amount of new information on the genetic causes of CMT has become available, and mutations causing it have been associated with more than 17 different genes and 25 chromosomal loci. Advances in our understanding of the molecular basis of CMT have revealed an enormous diversity in genetic mechanisms, despite a clinical entity that is relatively uniform in presentation. In addition, recent encouraging studies - shown in CMT1A animal models - concerning the therapeutic effects of certain chemicals have been published; these suggest potential therapies for the most common form of CMT, CMT1A. This review focuses on the inherited motor and sensory neuropathy subgroup for which there has been an explosion of new molecular genetic information over the past decade.
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Affiliation(s)
- Jung-Hwa Lee
- Department of Neurology and Ewha Medical Research Center, College of Medicine, Ewha Womans University, Seoul, Korea
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Otagiri T, Sugai K, Kijima K, Arai H, Sawaishi Y, Shimohata M, Hayasaka K. Periaxin mutation in Japanese patients with Charcot-Marie-Tooth disease. J Hum Genet 2006; 51:625-8. [PMID: 16770524 DOI: 10.1007/s10038-006-0408-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2006] [Accepted: 03/27/2006] [Indexed: 11/29/2022]
Abstract
Periaxin (PRX) plays an important role in the myelination of the peripheral nerve and consequently in the pathogenesis of Charcot-Marie-Tooth disease (CMT). To date, nine nonsense or frameshift PRX mutations have been reported in eight families with CMT. The patients with PRX mutations appeared to show characteristic clinical features with early onset but slow or no progression, a common result of mutations that lead to missing a C-terminal acidic domain. Here, we report a Japanese CMT patient with these characteristic clinical features, who was a compound heterozygote for PRX R1070X and L132FsX153 mutations. We previously reported that three Japanese isolated families also had the homozygous R1070X mutation. To examine the potential founder effect of the R1070X mutation in the Japanese population, we performed haplotype analysis and found that each R1070X allele lay on a different haplotype background in these four families. Therefore, the high frequency of the R1070X mutation among the Japanese population is not likely the consequence of a founder effect, but probably a result of a mutation hot spot.
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Affiliation(s)
- Tesshu Otagiri
- Department of Pediatrics, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan
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Senderek J, Hermanns B, Lehmann U, Bergmann C, Marx G, Kabus C, Timmerman V, Stoltenburg-Didinger G, Schröder JM. Charcot-Marie-Tooth neuropathy type 2 and P0 point mutations: two novel amino acid substitutions (Asp61Gly; Tyr119Cys) and a possible "hotspot" on Thr124Met. Brain Pathol 2006; 10:235-48. [PMID: 10764043 PMCID: PMC8098375 DOI: 10.1111/j.1750-3639.2000.tb00257.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Mutations in the gene for the major protein component of peripheral nerve myelin, myelin protein zero (MPZ, P0), cause hereditary disorders of Schwann cell myelin such as Charcot-Marie-Tooth neuropathy type 1B (CMT1B), Dejerine-Sottas syndrome (DSS), and congenital hypomyelinating neuropathy (CHN). More recently, P0 mutations were identified in the axonal type of CMT neuropathy, CMT2, which is different from the demyelinating variants with respect to electroneurography and nerve pathology. We screened 49 patients with a clinical and histopathological diagnosis of CMT2 for mutations in the P0 gene. Three heterozygous single nucleotide changes were detected: two novel missense mutations, Asp61Gly and Tyr119Cys, and the known Thr124Met substitution, that has already been reported in several CMT patients from different European countries. Haplotype analysis for the P0 locus proved that our patients with the 124Met allele were not related to a cohort of patients with the same mutation, all of Belgian descent and all found to share a common ancestor. Our data suggest that P0 mutations account for a detectable proportion of CMT2 cases with virtually every patient harbouring a different mutation but recurrence of the Thr124Met amino acid substitution. The high frequency of this peculiar genotype in the European CMT population is presumably not only due to a founder effect but Thr124Met might constitute a mutation hotspot in the P0 gene as well.
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Affiliation(s)
- J Senderek
- Institut für Neuropathologie, Universitätsklinikum der Rheinisch-Westfälischen Technischen Hochschule Aachen, Germany
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48
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Schröder JM. Neuropathology of Charcot-Marie-Tooth and related disorders. Neuromolecular Med 2006; 8:23-42. [PMID: 16775365 DOI: 10.1385/nmm:8:1-2:23] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2005] [Revised: 11/18/2005] [Accepted: 11/30/2005] [Indexed: 11/11/2022]
Abstract
The peripheral nervous system (PNS), with all its branches and connections, is so complex that it is impossible to study all components at the light or electron microscopic level in any individual case; nevertheless, in certain diseases a simple nerve biopsy may suffice to arrive at a precise diagnosis. Structural changes of the PNS in neuropathies of the Charcot-Marie-Tooth (CMT) type and related disorders comprise various components of the PNS. These include peripheral motor, sensory, and autonomous neurons with their axons, Schwann cells, and myelin sheaths in the radicular and peripheral nerves as well as satellite cells in spinal and autonomous ganglia. Astrocytes, oligodendroglial cells, and microglial cells around motor neurons in the anterior horn and around sensory neurons in other areas of the spinal cord are also involved. In addition, connective tissue elements such as endoneurial, perineurial, and epineurial components including blood and lymph vessels play an important role. This review focuses on the cellular components and organelles involved, that is, myelin sheaths, axons with their micro-tubules and neurofilaments; nuclei, mitochondria, endoplasmic reticulum, and connective tissue including the perineurium and blood vessels. A major role is attributed to recent progress in the pathomorphology of various types of CMT1, 2,4, CMTX, and HMNSL, based on light and electron microscopic findings, morphometry, teased fiber studies, and new immunohisto-chemical results such as staining of certain periaxin domains in CMT4F.
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Affiliation(s)
- J Michael Schröder
- Department of Neuropathology, University Hospital, RWTH Aachen, Germany.
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49
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Pareyson D, Scaioli V, Laurà M. Clinical and electrophysiological aspects of Charcot-Marie-Tooth disease. Neuromolecular Med 2006; 8:3-22. [PMID: 16775364 DOI: 10.1385/nmm:8:1-2:3] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Revised: 12/06/2005] [Accepted: 12/15/2005] [Indexed: 11/11/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) is a genetically heterogeneous group of disorders sharing the same clinical phenotype, characterized by distal limb muscle wasting and weakness, usually with skeletal deformities, distal sensory loss, and abnormalities of deep tendon reflexes. Mutations of genes involved in different functions eventually lead to a length-dependent axonal degeneration, which is the likely basis of the distal predominance of the CMT phenotype. Nerve conduction studies are important for classification, diagnosis, and understanding of pathophysiology. The subdivision into demyelinating CMT1 and axonal CMT2 types was a milestone and is still valid for the majority of patients. However, exceptions to this partition are increasing. Intermediate conduction velocities are often found in males with X-linked CMT (CMTX), and different intermediate CMT types have been identified. Moreover, for some genes, different mutations may result either in demyelinating CMT with slow conduction, or in axonal CMT. Nerve conduction slowing is uniform and diffuse in the most common CMT1A associated with the 17p12 duplication, whereas it is often asymmetric and nonhomogeneous in CMTX, sometimes rendering difficult the differential diagnosis with acquired inflammatory neuropathies. The demyelinating recessive forms, termed CMT4, usually have early onset and run a more severe course than the dominant types. Pure motor CMT types are now classified as distal hereditary motor neuronopathy. The diagnostic approach to the identification of the CMT subtype is complex and cannot be based on the clinical phenotype alone, as different forms are often clinically indistinguishable. However, there are features that may be of help in addressing molecular investigation in a single patient. Late onset, prominent or peculiar sensory manifestations, autonomic nervous system dysfunction, cranial nerve involvement, upper limb predominance, subclinical central nervous system abnormalities, severe scoliosis, early-onset glaucoma, neutropenia are findings helpful for diagnosis.
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Affiliation(s)
- D Pareyson
- Division of Biochemistry and Genetics, Carlo Besta National Neurological Institute, via Celoria, 11, 20133, Milan, Italy.
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Mikesová E, Hühne K, Rautenstrauss B, Mazanec R, Baránková L, Vyhnálek M, Horácek O, Seeman P. Novel EGR2 mutation R359Q is associated with CMT type 1 and progressive scoliosis. Neuromuscul Disord 2005; 15:764-7. [PMID: 16198564 DOI: 10.1016/j.nmd.2005.08.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2005] [Revised: 07/25/2005] [Accepted: 08/04/2005] [Indexed: 10/25/2022]
Abstract
Mutations in the early growth response 2 gene (EGR2) cause demyelinating neuropathies differing in severity and age of onset. We tested 46 unrelated Czech patients with dominant or sporadic demyelinating CMT neuropathy for mutations in the EGR2 gene. One novel de-novo mutation (Arg359Gln, R359Q) was identified in heterozygous state in a patient with a typical CMT1 phenotype, progressive moderate thoracolumbar scoliosis and without clinical signs of cranial nerve dysfunction. This patient is presently less affected compared to previously described Dejerine-Sottas neuropathy (DSN) patients carrying another substitution at codon 359 (Arg359Trp, R359W). This report shows that EGR2 mutations are rare in Czech patients with demyelinating type of CMT and suggests that different substitutions at codon 359 of EGR2 can cause significantly different phenotypes.
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Affiliation(s)
- E Mikesová
- Department of Child Neurology, 2nd School of Medicine, Charles University Prague, V Uvalu 84, 15006 Prague, Czech Republic.
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