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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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Hu TM, Chen CH, Chuang YA, Hsu SH, Cheng MC. Resequencing of early growth response 2 (EGR2) gene revealed a recurrent patient-specific mutation in schizophrenia. Psychiatry Res 2015; 228:958-60. [PMID: 26119399 DOI: 10.1016/j.psychres.2015.05.035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Revised: 05/18/2015] [Accepted: 05/28/2015] [Indexed: 02/06/2023]
Abstract
Abnormal myelination is considered as part of the pathophysiology of schizophrenia. We resequenced the genomic DNA of the EGR2, which has a specific function in the myelination of peripheral nervous system, in 543 schizophrenic patients and 554 non-psychotic controls. We identified six known SNPs, which were not associated with schizophrenia. Nevertheless, we discovered 24 rare mutations, some of them were patient-specific, including a recurrent mutation (p.P173_Y174insP), which might be associated with the pathogenesis of schizophrenia.
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Affiliation(s)
- Tsung-Ming Hu
- Department of Psychiatry, Yuli Mental Health Research Center, Yuli Branch, Taipei Veterans General Hospital, Hualien, Taiwan
| | - Chia-Hsiang Chen
- Department of Psychiatry, Chang Gung Memorial Hospital at Linkou and Department and Graduate School of Biomedical Sciences Chang Gung University, Taoyuan, Taiwan
| | - Yang-An Chuang
- Department of Psychiatry, Yuli Mental Health Research Center, Yuli Branch, Taipei Veterans General Hospital, Hualien, Taiwan
| | - Shih-Hsin Hsu
- Department of Psychiatry, Yuli Mental Health Research Center, Yuli Branch, Taipei Veterans General Hospital, Hualien, Taiwan
| | - Min-Chih Cheng
- Department of Psychiatry, Yuli Mental Health Research Center, Yuli Branch, Taipei Veterans General Hospital, Hualien, Taiwan; Center for General Education, St. Mary׳s Junior College of Medicine, Nursing and Management, Yilan County, Taiwan.
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Nicolaou P, Christodoulou K. Advances in the molecular diagnosis of Charcot-Marie-Tooth disease. World J Neurol 2013; 3:42-55. [DOI: 10.5316/wjn.v3.i3.42] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 07/23/2013] [Accepted: 08/16/2013] [Indexed: 02/06/2023] Open
Abstract
Charcot-Marie-Tooth (CMT) disease or hereditary motor and sensory neuropathy is the most common inherited neuromuscular disorder affecting at least 1 in 2500. CMT disease is pathologically and genetically heterogeneous and is characterized by a variable age of onset, slowly progressive weakness and muscle atrophy, starting in the lower limbs and subsequently affecting the upper extremities. Symptoms are usually slowly progressive, especially for the classic and late-onset phenotypes, but can be rather severe in early-onset forms. CMT is grouped into demyelinating, axonal and intermediate forms, based on electrophysiological and pathological findings. The demyelinating types are characterized by severely reduced motor nerve conduction velocities (MNCVs) and mainly by myelin abnormalities. The axonal types are characterized by normal or slightly reduced MNCVs and mainly axonal abnormalities. The intermediate types are characterized by MNCVs between 25 m/s and 45 m/s and they have features of both demyelination and axonopathy. Inheritance can be autosomal dominant, X-linked, or autosomal recessive. Mutations in more than 30 genes have been associated with the different forms of CMT, leading to major advancements in molecular diagnostics of the disease, as well as in the understanding of pathogenetic mechanisms. This editorial aims to provide an account that is practicable and efficient on the current molecular diagnostic procedures for CMT, in correlation with the clinical, pathological and electrophysiological findings. The most frequent causative mutations of CMT will also be outlined.
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Siskind CE, Panchal S, Smith CO, Feely SME, Dalton JC, Schindler AB, Krajewski KM. A review of genetic counseling for Charcot Marie Tooth disease (CMT). J Genet Couns 2013; 22:422-36. [PMID: 23604902 DOI: 10.1007/s10897-013-9584-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 03/20/2013] [Indexed: 02/07/2023]
Abstract
Charcot Marie Tooth disease (CMT) encompasses the inherited peripheral neuropathies. While four genes have been found to cause over 90 % of genetically identifiable causes of CMT (PMP22, GJB1, MPZ, MFN2), at least 51 genes and loci have been found to cause CMT when mutated, creating difficulties for clinicians to find a genetic subtype for families. Here, the classic features of CMT as well as characteristic features of the most common subtypes of CMT are described, as well as methods for narrowing down the possible subtypes. Psychosocial concerns particular to the CMT population are identified. This is the most inclusive publication for CMT-specific genetic counseling.
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Affiliation(s)
- Carly E Siskind
- Neurosciences Department, Stanford Hospital and Clinics, 300 Pasteur Dr., Stanford, CA 94305, USA.
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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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Shiga K, Noto Y, Mizuta I, Hashiguchi A, Takashima H, Nakagawa M. A novel EGR2 mutation within a family with a mild demyelinating form of Charcot-Marie-Tooth disease. J Peripher Nerv Syst 2012; 17:206-9. [DOI: 10.1111/j.1529-8027.2012.00403.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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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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9
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Charcot–Marie–Tooth diseases. Neurogenetics 2012. [DOI: 10.1017/cbo9781139087711.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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10
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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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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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12
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Adult onset charcot-marie-tooth disease type 1d with an Arg381Cys mutation of EGR2. Muscle Nerve 2010; 41:888-9. [DOI: 10.1002/mus.21663] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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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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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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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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Dubourg O, Azzedine H, Verny C, Durosier G, Birouk N, Gouider R, Salih M, Bouhouche A, Thiam A, Grid D, Mayer M, Ruberg M, Tazir M, Brice A, LeGuern E. Autosomal-recessive forms of demyelinating Charcot-Marie-Tooth disease. Neuromolecular Med 2007; 8:75-86. [PMID: 16775368 DOI: 10.1385/nmm:8:1-2:75] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Revised: 01/03/2006] [Accepted: 01/11/2006] [Indexed: 11/11/2022]
Abstract
Autosomal-recessive forms of Charcot-Marie-Tooth (ARCMT) account for less than 10% of the families in the European CMT population but are more frequent in the Mediterranean basin and the Middle East because of more widespread consanguinity. Until now, demyelinating ARCMT was more extensively studied at the genetic level than the axonal form. Since 1999, the number of localized or identified genes responsible for demyelinating ARCMT has greatly increased. Eight genes, EGR2, GDAP1, KIAA1985, MTMR2, MTMR13, NDRG1, PRX, and CTDP1, have been identified and two new loci mapped to chromosomes 10q23 and 12p11-q13. In this review, we will focus on the particular clinical and/or neuropathological features of the phenotype caused by mutations in each of these genes, which might guide molecular diagnosis.
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Affiliation(s)
- O Dubourg
- INSERM U679 (ex U289), la Pitié-Salpêtrière Hospital, AP-HP, Paris, France
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18
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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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19
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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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20
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Leblanc SE, Srinivasan R, Ferri C, Mager GM, Gillian-Daniel AL, Wrabetz L, Svaren J. Regulation of cholesterol/lipid biosynthetic genes by Egr2/Krox20 during peripheral nerve myelination. J Neurochem 2005; 93:737-48. [PMID: 15836632 DOI: 10.1111/j.1471-4159.2005.03056.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Myelination of peripheral nerves by Schwann cells requires a large amount of lipid and cholesterol biosynthesis. To understand the transcriptional coordination of the myelination process, we have investigated the developmental relationship between early growth response 2 (Egr2)/Krox20--a pivotal regulator of peripheral nerve myelination--and the sterol regulatory element binding protein (SREBP) pathway, which controls expression of cholesterol/lipid biosynthetic genes. During myelination of sciatic nerve, there is a very significant induction of SREBP1 and SREBP2, as well as their target genes, suggesting that the SREBP transactivators are important regulators in the myelination process. Egr2/Krox20 does not appear to directly regulate the levels of SREBP pathway components, but rather, we found that Egr2/Krox20 and SREBP transactivators can synergistically activate promoters of several SREBP target genes, indicating that direct induction of cholesterol/lipid biosynthetic genes by Egr2/Krox20 is a part of the myelination program regulated by this transactivator.
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Affiliation(s)
- Scott E Leblanc
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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21
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Abstract
Charcot-Marie-Tooth (CMT), or heritable peripheral neuropathies, is among the most frequent genetic neuromuscular disorders, with a prevalence of approximately 1:2500. Since 1991, remarkable advances have occurred in determining the precise genetic cause of many forms of CMT and in generating animal models of many of these disorders. However, these advances have not yet resulted in cures for CMT. Recently, potential treatments for the most common form of CMT, CMT-1A, have been shown in rodent models of the disorder. Treatment with onapristone, a progesterone antagonist, has improved the neuropathy of the CMT-1A rat. Treatment with large doses of ascorbic acid (vitamin C) has improved the neuropathy of the CMT-1A mouse. Multicentric trials with ascorbic acid are likely to start in the near future to assess if vitamin C supplementation is effective and what is the dosage required in humans to improve neurologic disability. Because of potential side effects with antiprogesterone therapy, particularly in women of child- bearing age, research is actively proceeding with progesterone antagonists to develop safe medications that also can be used in clinical trials of CMT-1A. Although no cures are available for CMT, there are many important treatments available for patients with CMT that can improve their quality of life and help them maintain their independence. Some of these therapies involve physiatry and orthopedic surgery. Others involve pain management. Lastly, there are potential concerns about medications or lifestyle issues that may exacerbate CMT. All of these issues will be discussed.
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Affiliation(s)
- Marina Grandis
- Department of Neurology, Wayne State University, 4201 Saint Antoine Street, Detroit, MI 48201, USA.
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22
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Gillian AL, Svaren J. The Ddx20/DP103 Dead Box Protein Represses Transcriptional Activation by Egr2/Krox-20. J Biol Chem 2004; 279:9056-63. [PMID: 14699164 DOI: 10.1074/jbc.m309308200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The early growth response 2 (Egr2/Krox-20) transcription factor is essential for myelination of the peripheral nervous system and segmentation of the vertebrate hindbrain. To probe the mechanism by which Egr2 is regulated, we used a yeast two-hybrid assay and identified an RNA helicase, Ddx20 (DP103/Gemin3), as an Egr2-interacting protein. Mammalian two-hybrid assays indicated that Ddx20 can interact with Egr1, Egr3, and Egr4, in addition to Egr2, making it the only known cofactor that interacts with all four Egr family members. Using several Egr2 target promoters, we found that Ddx20 repressed Egr2-mediated transcriptional activation with significant promoter specificity. In addition, Ddx20 repressed Egr2-mediated activation of the endogenous insulin-like growth factor 2 (IGF2) gene. Interestingly, the C-terminal segment of Ddx20, which lacks the DEAD box helicase domain, was sufficient for its robust and specific repression. We also examined possible interactions between Ddx20 and Nab proteins, the only other known corepressors of the Egr family, and found that these two corepressors act independently. Finally, transcriptional repression assays performed in the presence of a histone deacetylase inhibitor (trichostatin A) indicate that although repression of certain promoters by Ddx20 requires histone deacetylase activity, another repression mechanism must also be involved. Because Egr2 is critical for hindbrain development and peripheral nerve myelination, modulation of Egr2 by Ddx20 may play an important role in maintaining the correct expression level of Egr2 target genes.
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Affiliation(s)
- Anne Lynn Gillian
- Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
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23
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Numakura C, Shirahata E, Yamashita S, Kanai M, Kijima K, Matsuki T, Hayasaka K. Screening of the early growth response 2 gene in Japanese patients with Charcot-Marie-Tooth disease type 1. J Neurol Sci 2003; 210:61-4. [PMID: 12736090 DOI: 10.1016/s0022-510x(03)00028-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Charcot-Marie-Tooth disease type 1 (CMT1) is a heterogeneous disorder. Most CMT1 patients are associated with a duplication of 17p11.2-p12 (CMT1A duplication), but a small number of patients have mutations of peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ), connexin 32 (Cx32) and early growth response 2 (EGR2) genes. In our previous study, we identified the responsible mutations in 72 of 128 Japanese CMT1 patients as CMT1A duplication in 40, PMP22 mutation in 6, MPZ mutation in 12 and Cx32 mutation in 14 patients. A total of 56 Japanese CMT1 patients with no identified mutations were screened for EGR2 mutation by denaturing gradient gel electrophoresis (DGGE). We detected a heterozygous Asp383Tyr mutation of EGR2 in one patient with severe CMT1, Dejerine-Sottas syndrome. EGR2 mutation is rare cause of CMT1 in Japan as in other nations. We were unable to identify the responsible mutation in 55 of 128 CMT1 patients and need further analysis to identify their candidate genes.
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Affiliation(s)
- Chikahiko Numakura
- Department of Pediatrics, Yamagata University School of Medicine, Yamagata 990-9585, Japan
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24
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Musso M, Balestra P, Taroni F, Bellone E, Mandich P. Different consequences of EGR2 mutants on the transactivation of human Cx32 promoter. Neurobiol Dis 2003; 12:89-95. [PMID: 12609493 DOI: 10.1016/s0969-9961(02)00018-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
The early growth response 2 (EGR2) transcription factor plays a crucial role in peripheral nerve myelination. Mutations of this gene are associated with a wide variety of demyelinating neuropathies differing from each other in the severity of nerve injury. Although the expression of EGR2 mutants inhibits the transactivation of myelin gene promoters, the exact molecular mechanism by which these mutations cause the alteration of the myelination process is still unknown. Recently, it was reported that EGR2 is directly involved in the transcriptional regulation of Connexin 32, a myelin gene frequently mutated in peripheral neuropathies. Here we describe the differential effect of two EGR2 mutants; while mutant D355V partially induces Cx32 promoter, mutant R381H does not. Furthermore, we show that a sequence located at -216, recognized by the wild-type and the mutant D355V recombinant proteins, is relevant for promoter transactivation.
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Affiliation(s)
- Marco Musso
- Department of Neurosciences, Ophthalmology, and Genetics, University of Genoa, c/o DIMI Viale Benedetto XV, 6-16132 Genova, Italy.
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25
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Hattori N, Yamamoto M, Yoshihara T, Koike H, Nakagawa M, Yoshikawa H, Ohnishi A, Hayasaka K, Onodera O, Baba M, Yasuda H, Saito T, Nakashima K, Kira JI, Kaji R, Oka N, Sobue G. Demyelinating and axonal features of Charcot-Marie-Tooth disease with mutations of myelin-related proteins (PMP22, MPZ and Cx32): a clinicopathological study of 205 Japanese patients. Brain 2003; 126:134-51. [PMID: 12477701 DOI: 10.1093/brain/awg012] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Three genes commonly causing Charcot-Marie-Tooth disease (CMT) encode myelin-related proteins: peripheral myelin protein 22 (PMP22), myelin protein zero (MPZ) and connexin 32 (Cx32). Demyelinating versus axonal phenotypes are major issues in CMT associated with mutations of these genes. We electrophysiologically, pathologically and genetically evaluated demyelinating and axonal features of 205 Japanese patients with PMP22 duplication, MPZ mutations or Cx32 mutations. PMP22 duplication caused mainly demyelinating phenotypes with slowed motor nerve conduction velocity (MCV) and demyelinating histopathology, while axonal features were variably present. Two distinctive phenotypic subgroups were present in patients with MPZ mutations: one showed preserved MCV and exclusively axonal pathological features, while the other was exclusively demyelinating. These axonal and demyelinating phenotypes were well concordant among siblings in individual families, and MPZ mutations did not overlap among these two subgroups, suggesting that the nature and position of the MPZ mutations mainly determine the axonal and demyelinating phenotypes. Patients with Cx32 mutations showed intermediate slowing of MCV, predominantly axonal features and relatively mild demyelinating pathology. These axonal and demyelinating features were present concomitantly in individual patients to a variable extent. The relative severity of axonal and demyelinating features was not associated with particular Cx32 mutations. Median nerve MCV and overall histopathological phenotype changed little with disease advancement. Axonal features of diminished amplitudes of compound muscle action potentials (CMAPs), axonal loss, axonal sprouting and neuropathic muscle wasting all changed as disease advanced, especially in PMP22 duplication and Cx32 mutations. Median nerve MCVs were well maintained independently of age, disease duration and the severity of clinical and pathological abnormalities, confirming that median nerve MCV is an excellent marker for the genetically determined neuropathic phenotypes. Amplitude of CMAPs was correlated significantly with distal muscle strength in PMP22 duplication, MPZ mutations and Cx32 mutations, while MCV slowing was not, indicating that clinical weakness results from reduced numbers of functional large axons, not from demyelination. Thus, the three major myelin-related protein mutations induced varied degrees of axonal and demyelinating phenotypic features according to the specific gene mutation as well as the stage of disease advancement, while clinically evident muscle wasting was attributable to loss of functioning large axons.
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Affiliation(s)
- Naoki Hattori
- Department of Neurology, Nagoya University Graduate School of Medicine, Nagoya, Japan
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26
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Abstract
Mutations in genes expressed in Schwann cells and the axons they ensheath cause the hereditary motor and sensory neuropathies known as Charcot-Marie-Tooth (CMT) disease. At present, mutations in ten different genes have been identified, chromosomal localisation of many other distinct inherited neuropathies has been mapped, and new genetic causes for inherited neuropathies continue to be discovered. How to keep track of these mutations is a challenge for any neurologist, partly because the mutations are commonly presented as an expanding list to be memorised without a biological context of how the encoded proteins behave in the cell. A further challenge for investigators studying diseases of the peripheral nervous system is the increasing complexity of myelination, axonal function, and interactions between Schwann cells and axons. To address these concerns, we present the mutated genes causing these inherited neuropathies in the context of the cell biology of the Schwann cell and axon, and we begin to develop a model of how the various genes may interact in the pathogenesis of CMT disease.
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Affiliation(s)
- Michael E Shy
- Department of Neurology and the Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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27
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Moore EE, Presnell S, Garrigues U, Guilbot A, LeGuern E, Smith D, Yao L, Whitmore TE, Gilbert T, Palmer TD, Horner PJ, Kuestner RE. Expression of IL-17B in neurons and evaluation of its possible role in the chromosome 5q-linked form of Charcot-Marie-Tooth disease. Neuromuscul Disord 2002; 12:141-50. [PMID: 11738356 DOI: 10.1016/s0960-8966(01)00250-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
IL-17B is a recently identified homolog of IL-17. Northern analysis revealed that IL-17B mRNA is expressed at very high levels in spinal cord and at much lower and more variable levels in trachea, prostate, lung, small intestine, testes, adrenal, and pancreas. In developing mouse embryos IL-17B expression was first detected at day 11 and appeared to peak at day 15. In situ analysis of mouse spinal cord, dorsal root ganglia, and brain demonstrated that IL-17B mRNA is primarily expressed by the neurons. Immunohistochemical analysis of human spinal cord, dorsal root ganglia, cerebral cortex, cerebellum, and hippocampus demonstrated that IL-17B protein is primarily localized to the neuronal cell bodies and axons. Radiation hybrid mapping localized the IL-17B gene to a region on human chromosome 5q that is associated with a rare autosomal recessive form of Charcot-Marie-Tooth demyelinating disease. However, no changes were found in the coding regions, splice junctions, intron 1, or the 5' and 3' untranslated regions of IL-17B genes of patients affected with this disease.
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Affiliation(s)
- Emma E Moore
- ZymoGenetics Inc, 1201 Eastlake Avenue East, Seattle, WA 98102, USA.
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