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Uncini A, Cavallaro T, Fabrizi GM, Manganelli F, Vallat JM. Conduction slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies: Electrophysiology meets pathology. J Peripher Nerv Syst 2024; 29:135-160. [PMID: 38600691 DOI: 10.1111/jns.12625] [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: 01/23/2024] [Revised: 03/02/2024] [Accepted: 03/28/2024] [Indexed: 04/12/2024]
Abstract
Nerve conduction studies are usually the first diagnostic step in peripheral nerve disorders and their results are the basis for planning further investigations. However, there are some commonplaces in the interpretation of electrodiagnostic findings in peripheral neuropathies that, although useful in the everyday practice, may be misleading: (1) conduction block and abnormal temporal dispersion are distinctive features of acquired demyelinating disorders; (2) hereditary neuropathies are characterized by uniform slowing of conduction velocity; (3) axonal neuropathies are simply diagnosed by reduced amplitude of motor and sensory nerve action potentials with normal or slightly slow conduction velocity. In this review, we reappraise the occurrence of uniform and non-uniform conduction velocity slowing, conduction block and temporal dispersion in demyelinating, dysmyelinating and axonal neuropathies attempting, with a translational approach, a correlation between electrophysiological and pathological features as derived from sensory nerve biopsy in patients and animal models. Additionally, we provide some hints to navigate in this complex field.
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Affiliation(s)
- Antonino Uncini
- Department of Neurosciences, Imaging and Clinical Sciences, University "G. d'Annunzio", Chieti-Pescara, Italy
| | - Tiziana Cavallaro
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Gian Maria Fabrizi
- Department of Neurosciences, Biomedicine, and Movement Sciences, University of Verona, Verona, Italy
| | - Fiore Manganelli
- Department of Neurosciences, Reproductive Sciences and Odontostomatology, University of Naples "Federico II", Naples, Italy
| | - Jean-Michel Vallat
- Department of Neurology, National Reference Center for "Rare Peripheral Neuropathies", CHU Dupuytren, Limoges, France
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Chen Z, Saini M, Neo SXM, Ng PS, Koh JS, Prasad K, Verma K, Davila S, Lim WK, Phua Z, Li MM, Kang C, Tay KSS, Chai JYH. Acute to Subacute Atraumatic Entrapment Neuropathies in Patients With CMT1A: A Report of a Distinct Phenotypic Variant of CMT1A. Front Neurol 2022; 13:826634. [PMID: 35280294 PMCID: PMC8914073 DOI: 10.3389/fneur.2022.826634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Charcot-Marie-Tooth type 1A (CMT1A) is typically characterised as a childhood-onset, symmetrical, length-dependent polyneuropathy with a gradual progressive clinical course. Acute to subacute neurological deterioration in CMT1A is rare, and has been reported secondary to overlap pathologies including inflammatory neuropathy. We identified two patients with CMT1A who presented with acute to subacute, atraumatic, entrapment neuropathies as an initial symptom. A superimposed inflammatory neuropathy was excluded. Both patients had a diffuse demyelinating polyneuropathy, with markedly low motor nerve conduction velocities (<20 m/s). In both patients, we demonstrated symptomatic and asymptomatic partial conduction blocks at multiple entrapment sites. Nerve ultrasound findings in our patients demonstrated marked diffuse nerve enlargement, more pronounced at non-entrapment sites compared to entrapment sites. We discuss ways to distinguish this condition from its other differentials. We propose pathophysiological mechanisms underlying this condition. We propose that CMT1A with acute to subacute, atraumatic, entrapment neuropathies to be a distinct phenotypic variant of CMT1A.
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Affiliation(s)
- Zhiyong Chen
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- *Correspondence: Zhiyong Chen
| | - Monica Saini
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
| | - Shermyn X. M. Neo
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
| | - Peng-Soon Ng
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
| | - Jasmine S. Koh
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
| | - Kalpana Prasad
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
| | - Kamal Verma
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
| | - Sonia Davila
- Singhealth Duke-National University of Singapore (NUS) Institute of Precision Medicine, Singapore, Singapore
- Cardiovascular and Metabolic Disorders, Duke-National University of Singapore (NUS) Medical School, Singapore, Singapore
- SingHealth Duke-National University of Singapore (NUS) Genomic Medicine Centre, Singapore, Singapore
| | - Weng Khong Lim
- Singhealth Duke-National University of Singapore (NUS) Institute of Precision Medicine, Singapore, Singapore
- SingHealth Duke-National University of Singapore (NUS) Genomic Medicine Centre, Singapore, Singapore
- Cancer and Stem Cell Biology Program, Duke-National University of Singapore (NUS) Medical School, Singapore, Singapore
| | - Ziqun Phua
- Neurodiagnostic Laboratory, National Neuroscience Institute, Singapore, Singapore
| | - Michelle M. Li
- Neurodiagnostic Laboratory, National Neuroscience Institute, Singapore, Singapore
| | - Corrine Kang
- Clinical Measurement Unit, Changi General Hospital, Singapore, Singapore
| | - Karine S. S. Tay
- Neuromuscular Laboratory, National Neuroscience Institute, Singapore, Singapore
| | - Josiah Y. H. Chai
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
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Turčanová Koprušáková M, Grofik M, Kantorová E, Jungová P, Chandoga J, Kolisek M, Valkovič P, Škorvánek M, Ploski R, Kurča E, Sivák Š. Atypical presentation of Charcot-Marie-Tooth disease type 1C with a new mutation: a case report. BMC Neurol 2021; 21:293. [PMID: 34311727 PMCID: PMC8314550 DOI: 10.1186/s12883-021-02316-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 07/07/2021] [Indexed: 11/21/2022] Open
Abstract
Background Charcot-Marie-Tooth 1C (CMT1C) is a rare form of dominantly inherited CMT1 neuropathy caused by a mutated gene encoding lipopolysaccharide-induced tumour necrosis alpha factor (LITAF). Case presentation We report a 56-year-old patient with an atypical clinical phenotype of CMT1C, which started as progressive weakness of a single upper limb resembling acquired inflammatory neuropathy. Nerve conduction studies (NCS) and temporarily limited and partial effects of immunotherapy supported the diagnosis of inflammatory neuropathy. Significant progression of polyneuropathy, despite intensive long-lasting immunotherapy, together with repeatedly negative auxiliary investigations (CSF, MRI and antibodies) and genetic testing results finally led to the diagnosis of CMT1C neuropathy. Conclusions CMT1C should be added to the list of inherited neuropathies that need to be considered in suspected cases of inflammatory demyelinating neuropathy.
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Affiliation(s)
- Monika Turčanová Koprušáková
- Clinic of Neurology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Kollárova 2, 036 01, Martin, Slovak Republic
| | - Milan Grofik
- Clinic of Neurology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Kollárova 2, 036 01, Martin, Slovak Republic
| | - Ema Kantorová
- Clinic of Neurology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Kollárova 2, 036 01, Martin, Slovak Republic
| | - Petra Jungová
- Institute of Medical Biology, Genetics and Clinical Genetics, Faculty of Medicine, Comenius University and University Hospital in Bratislava, Bratislava, Slovak Republic
| | - Ján Chandoga
- Institute of Medical Biology, Genetics and Clinical Genetics, Faculty of Medicine, Comenius University and University Hospital in Bratislava, Bratislava, Slovak Republic
| | - Martin Kolisek
- Biomedical Center Martin, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Mala Hora 4b, 036 01, Martin, Slovak Republic
| | - Peter Valkovič
- 2nd Department of Neurology, Comenius University and University Hospital in Bratislava, Bratislava, Slovak Republic.,Centre of Experimental Medicine, Institute of Normal and Pathological Physiology, Slovak Academy of Sciences, Slovak, Slovak Republic
| | - Matej Škorvánek
- Department of Neurology, P.J. Safarik University and Louis Pasteur University Hospital, Kosice, Slovak Republic
| | - Rafal Ploski
- Department of Medical Genetics Laboratory, Medical University of Warsaw, Warsaw, Poland
| | - Egon Kurča
- Clinic of Neurology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Kollárova 2, 036 01, Martin, Slovak Republic
| | - Štefan Sivák
- Clinic of Neurology, Jessenius Faculty of Medicine in Martin, Comenius University in Bratislava, Kollárova 2, 036 01, Martin, Slovak Republic.
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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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Dehbashi S, Jin P, Edelschick D, Shin S. Clinical Reasoning: A 53-year-old woman with lower extremity paresthesias. Neurology 2020; 94:1105-1108. [PMID: 32461279 DOI: 10.1212/wnl.0000000000009645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Affiliation(s)
- Sara Dehbashi
- From the Jefferson University Hospitals (S.D.), Philadelphia, PA; University of Maryland School of Medicine (P.J.), Baltimore; private practice (D.E.); and Icahn School of Medicine at Mount Sinai (S.S.), New York
| | - Peter Jin
- From the Jefferson University Hospitals (S.D.), Philadelphia, PA; University of Maryland School of Medicine (P.J.), Baltimore; private practice (D.E.); and Icahn School of Medicine at Mount Sinai (S.S.), New York
| | - Donald Edelschick
- From the Jefferson University Hospitals (S.D.), Philadelphia, PA; University of Maryland School of Medicine (P.J.), Baltimore; private practice (D.E.); and Icahn School of Medicine at Mount Sinai (S.S.), New York
| | - Susan Shin
- From the Jefferson University Hospitals (S.D.), Philadelphia, PA; University of Maryland School of Medicine (P.J.), Baltimore; private practice (D.E.); and Icahn School of Medicine at Mount Sinai (S.S.), New York.
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Michaelidou K, Tsiverdis I, Erimaki S, Papadimitriou D, Amoiridis G, Papadimitriou A, Mitsias P, Zaganas I. Whole exome sequencing establishes diagnosis of Charcot-Marie-Tooth 4J, 1C, and X1 subtypes. Mol Genet Genomic Med 2020; 8:e1141. [PMID: 32022442 PMCID: PMC7196464 DOI: 10.1002/mgg3.1141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 01/01/2020] [Accepted: 01/03/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Charcot-Marie-Tooth (CMT) hereditary polyneuropathies pose a diagnostic challenge. Our aim here is to describe CMT patients diagnosed by whole exome sequencing (WES) following years of fruitless testing. METHODS/RESULTS Three patients with polyneuropathy suspected to be genetic in origin, but not harboring PMP22 gene deletion/duplication, were offered WES. The first patient, a 66-year-old man, had been suffering from progressive weakness and atrophies in the lower and upper extremities for 20 years. Due to ambiguous electrophysiological findings, immune therapies were administered to no avail. Twelve years after PMP22 deletion/duplication testing, WES revealed two pathogenic variants in the FIG4 gene (p.Ile41Thr and p.Phe598fs, respectively), as a cause of CMT 4J. The second patient, a 19-year-old man, had been suffering from hearing and gait impairment since at least his infancy, and recently presented with weakness and dystonia of the lower extremities. In this patient, WES identified the p.Leu122Val LITAF gene variant in heterozygous state, suggesting the diagnosis of CMT 1C, several years after initial genetic analyses. The third patient, a 44-year-old man, presented with progressive weakness and atrophies of the lower and upper extremities since the age of 17 years old. In this patient, WES identified the hemizygous p.Arg164Gln pathogenic variant in the GJB1 gene, establishing the diagnosis of CMT X1, 8 years after testing for PMP22 deletion/duplication. CONCLUSION Novel diagnostic techniques, such as WES, offer the possibility to decipher the cause of CMT subtypes, ending the diagnostic Odyssey of the patients and sparing them from unnecessary and potentially harmful treatments.
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Affiliation(s)
- Kleita Michaelidou
- Neurogenetics LaboratoryMedical SchoolUniversity of CreteHeraklion, CreteGreece
| | - Ioannis Tsiverdis
- Neurology DepartmentUniversity Hospital of CreteHeraklion, CreteGreece
| | - Sophia Erimaki
- Neurophysiology UnitUniversity Hospital of CreteHeraklion, CreteGreece
| | | | | | | | - Panayiotis Mitsias
- Neurogenetics LaboratoryMedical SchoolUniversity of CreteHeraklion, CreteGreece
- Neurology DepartmentUniversity Hospital of CreteHeraklion, CreteGreece
- Neurophysiology UnitUniversity Hospital of CreteHeraklion, CreteGreece
- Department of NeurologyHenry Ford Hospital/Wayne State UniversityDetroitMIUSA
| | - Ioannis Zaganas
- Neurogenetics LaboratoryMedical SchoolUniversity of CreteHeraklion, CreteGreece
- Neurology DepartmentUniversity Hospital of CreteHeraklion, CreteGreece
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7
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Moshal KS, Roder K, Kabakov AY, Werdich AA, Yi-Eng Chiang D, Turan NN, Xie A, Kim TY, Cooper LL, Lu Y, Zhong M, Li W, Terentyev D, Choi BR, Karma A, MacRae CA, Koren G. LITAF (Lipopolysaccharide-Induced Tumor Necrosis Factor) Regulates Cardiac L-Type Calcium Channels by Modulating NEDD (Neural Precursor Cell Expressed Developmentally Downregulated Protein) 4-1 Ubiquitin Ligase. CIRCULATION. GENOMIC AND PRECISION MEDICINE 2019; 12:407-420. [PMID: 31462068 PMCID: PMC6750970 DOI: 10.1161/circgen.119.002641] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND The turnover of cardiac ion channels underlying action potential duration is regulated by ubiquitination. Genome-wide association studies of QT interval identified several single-nucleotide polymorphisms located in or near genes involved in protein ubiquitination. A genetic variant upstream of LITAF (lipopolysaccharide-induced tumor necrosis factor) gene prompted us to determine its role in modulating cardiac excitation. METHODS Optical mapping was performed in zebrafish hearts to determine Ca2+ transients. Live-cell confocal calcium imaging was performed on adult rabbit cardiomyocytes to determine intracellular Ca2+handling. L-type calcium channel (LTCC) current (ICa,L) was measured using whole-cell recording. To study the effect of LITAF on Cav1.2 (L-type voltage-gated calcium channel 1.2) channel expression, surface biotinylation, and Westerns were performed. LITAF interactions were studied using coimmunoprecipitation and in situ proximity ligation assay. RESULTS LITAF knockdown in zebrafish resulted in a robust increase in calcium transients. Overexpressed LITAF in 3-week-old rabbit cardiomyocytes resulted in a decrease in ICa,L and Cavα1c abundance, whereas LITAF knockdown increased ICa,L and Cavα1c protein. LITAF-overexpressing decreases calcium transients in adult rabbit cardiomyocytes, which was associated with lower Cavα1c levels. In tsA201 cells, overexpressed LITAF downregulated total and surface pools of Cavα1c via increased Cavα1c ubiquitination and its subsequent lysosomal degradation. We observed colocalization between LITAF and LTCC in tsA201 and cardiomyocytes. In tsA201, NEDD (neural precursor cell expressed developmentally downregulated protein) 4-1, but not its catalytically inactive form NEDD4-1-C867A, increased Cavα1c ubiquitination. Cavα1c ubiquitination was further increased by coexpressed LITAF and NEDD4-1 but not NEDD4-1-C867A. NEDD4-1 knockdown abolished the negative effect of LITAF on ICa,L and Cavα1c levels in 3-week-old rabbit cardiomyocytes. Computer simulations demonstrated that a decrease of ICa,L current associated with LITAF overexpression simultaneously shortened action potential duration and decreased calcium transients in rabbit cardiomyocytes. CONCLUSIONS LITAF acts as an adaptor protein promoting NEDD4-1-mediated ubiquitination and subsequent degradation of LTCC, thereby controlling LTCC membrane levels and function and thus cardiac excitation.
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Affiliation(s)
- Karni S. Moshal
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Karim Roder
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Anatoli Y. Kabakov
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Andreas A. Werdich
- Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - David Yi-Eng Chiang
- Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Nilüfer N. Turan
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - An Xie
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Tae Yun Kim
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | | | - Yichun Lu
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Mingwang Zhong
- Physics Dept & Center for Interdisciplinary Research in Complex Systems, Northeastern Univ, Boston, MA
| | - Weiyan Li
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Dmitry Terentyev
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Bum-Rak Choi
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
| | - Alain Karma
- Physics Dept & Center for Interdisciplinary Research in Complex Systems, Northeastern Univ, Boston, MA
| | - Calum A. MacRae
- Cardiovascular Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA
| | - Gideon Koren
- Cardiovascular Research Center, Division of Cardiology, Dept of Medicine, Rhode Island Hospital, The Warren Alpert Medical School, Brown Univ, Providence, RI
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Charcot-Marie-Tooth: From Molecules to Therapy. Int J Mol Sci 2019; 20:ijms20143419. [PMID: 31336816 PMCID: PMC6679156 DOI: 10.3390/ijms20143419] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 07/03/2019] [Accepted: 07/03/2019] [Indexed: 01/08/2023] Open
Abstract
Charcot-Marie-Tooth (CMT) is the most prevalent category of inherited neuropathy. The most common inheritance pattern is autosomal dominant, though there also are X-linked and autosomal recessive subtypes. In addition to a variety of inheritance patterns, there are a myriad of genes associated with CMT, reflecting the heterogeneity of this disorder. Next generation sequencing (NGS) has expanded and simplified the diagnostic yield of genes/molecules underlying and/or associated with CMT, which is of paramount importance in providing a substrate for current and future targeted disease-modifying treatment options. Considerable research attention for disease-modifying therapy has been geared towards the most commonly encountered genetic mutations (PMP22, GJB1, MPZ, and MFN2). In this review, we highlight the clinical background, molecular understanding, and therapeutic investigations of these CMT subtypes, while also discussing therapeutic research pertinent to the remaining less common CMT subtypes.
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Guimarães-Costa R, Iancu Ferfoglia R, Leonard-Louis S, Ziegler F, Magy L, Fournier E, Dubourg O, Bouche P, Maisonobe T, Lacour A, Moerman A, Latour P, Stojkovic T. Phenotypic spectrum of Charcot-Marie-Tooth disease due to LITAF/SIMPLE mutations: a study of 18 patients. Eur J Neurol 2017; 24:530-538. [PMID: 28211240 DOI: 10.1111/ene.13239] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 11/30/2016] [Indexed: 01/11/2023]
Abstract
BACKGROUND AND PURPOSE Charcot-Marie-Tooth (CMT) 1C due to mutations in LITAF/SIMPLE is a rare subtype amongst the autosomal dominant demyelinating forms of CMT. Our objective was to report the clinical and electrophysiological characteristics of 18 CMT1C patients and compare them to 20 patients with PMP22 mutations: 10 CMT1A patients and 10 patients with hereditary neuropathy with liability to pressure palsies (HNPP). METHODS Charcot-Marie-Tooth 1C patients were followed-up in referral centres for neuromuscular diseases or were identified by familial survey. All CMT1A and HNPP patients were recruited at the referral centre for neuromuscular diseases of Pitié-Salpêtrière Hospital. RESULTS Two phenotypes were identified amongst 18 CMT1C patients: the classical CMT form ('CMT-like', 11 cases) and a predominantly sensory form ('sensory form', seven cases). The mean CMT neuropathy score was 4.45 in CMT1C patients. Motor nerve conduction velocities in the upper limbs were significantly more reduced in CMT1A than in CMT1C patients. On the other hand, the motor nerve conduction velocity of the median nerve was significantly lower in CMT1C compared to the HNPP group. Distal motor latency was significantly more prolonged in CMT1A patients compared to the CMT1C and HNPP groups, the latter two groups having similar distal motor latency values. Molecular analysis revealed five new LITAF/SIMPLE mutations (Ala111Thr, Gly112Ala, Trp116Arg, Pro135Leu, Arg160Cys). CONCLUSIONS Our study delineates CMT1C as mostly a mild form of neuropathy, and gives clinical and electrophysiological clues differentiating CMT1C from CMT1A and HNPP. Delineating phenotypes in CMT subtypes is important to orient molecular diagnosis and to help to interpret complex molecular findings.
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Affiliation(s)
- R Guimarães-Costa
- Centre de Référence des Maladies Neuromusculaires Paris Est, Institut de Myologie, Hôpital Pitié-Salpêtrière, Paris, France
| | - R Iancu Ferfoglia
- Centre de Référence des Maladies Neuromusculaires Paris Est, Institut de Myologie, Hôpital Pitié-Salpêtrière, Paris, France
| | - S Leonard-Louis
- Centre de Référence des Maladies Neuromusculaires Paris Est, Institut de Myologie, Hôpital Pitié-Salpêtrière, Paris, France
| | - F Ziegler
- Service de Neurologie, Centre Hospitalier Intercommunale de la Haute Saône, Vesoul, France
| | - L Magy
- Centre de Référence Neuropathies Périphérique Rares, CHU de Limoges - Hôpital Dupuytren, Limoges, France
| | - E Fournier
- Département de Neurophysiologie Clinique, Hôpital Pitié-Salpêtrière, Paris, France
| | - O Dubourg
- Centre de Référence des Maladies Neuromusculaires Paris Est, Institut de Myologie, Hôpital Pitié-Salpêtrière, Paris, France
| | - P Bouche
- Département de Neurophysiologie Clinique, Hôpital Pitié-Salpêtrière, Paris, France
| | - T Maisonobe
- Département de Neurophysiologie Clinique, Hôpital Pitié-Salpêtrière, Paris, France
| | - A Lacour
- Clinique Neurologique, Centre Hospitalier Universitaire de Lille, Lille, France
| | - A Moerman
- Département de Génétique Médicale, Hôpital Jeanne de Flandres, Centre Hospitalier Universitaire de Lille, Lille, France
| | - P Latour
- Service de Neurobiologie, Centre de Biologie et Pathologie Est, Centre Hospitalier Universitaire de Lyon HCL, GH Est, Lyon, France
| | - T Stojkovic
- Centre de Référence des Maladies Neuromusculaires Paris Est, Institut de Myologie, Hôpital Pitié-Salpêtrière, Paris, France
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Jerath NU, Shy ME. Charcot-Marie-Tooth disease type 1C: Clinical and electrophysiological findings for the c.334G>a (p.Gly112Ser) Litaf/Simple mutation. Muscle Nerve 2017; 56:1092-1095. [PMID: 28164329 DOI: 10.1002/mus.25600] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2017] [Indexed: 01/06/2023]
Abstract
INTRODUCTION Charcot-Marie-Tooth disease type 1C (CMT1C) is a rare, dominantly inherited neuropathy caused by mutations in the lipopolysaccharide-induced tumor necrosis factor (LITAF) or small integral membrane protein of the lysosome/late endosome (SIMPLE) gene. METHODS We present a case series comprised of 10 patients in whom CMT1C is caused by a Gly112Ser substitution in the encoded protein. We focus on clinical presentation, electrodiagnostic analyses, and our findings in the context of previously described cases. RESULTS The Gly112Ser mutation causing CMT1C is a mild form of CMT, as patients walked on time, had less weakness than those with Charcot-Marie-Tooth disease type 1A (CMT1A), had a CMT neuropathy score (CMTNS) indicative of mild disease, and had faster ulnar and median motor nerve conduction velocities compared to those with CMT1A. DISCUSSION The G112S mutation in LITAF seems to be clinically indistinguishable from a mild presentation of CMT1A. Muscle Nerve 56: 1092-1095, 2017.
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Affiliation(s)
- Nivedita U Jerath
- Department of Neurology, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA
| | - Michael E Shy
- Department of Neurology, University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, Iowa, 52242, USA
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Ho AK, Wagstaff JL, Manna PT, Wartosch L, Qamar S, Garman EF, Freund SMV, Roberts RC. The topology, structure and PE interaction of LITAF underpin a Charcot-Marie-Tooth disease type 1C. BMC Biol 2016; 14:109. [PMID: 27927196 PMCID: PMC5142333 DOI: 10.1186/s12915-016-0332-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/16/2016] [Indexed: 02/03/2023] Open
Abstract
BACKGROUND Mutations in Lipopolysaccharide-induced tumour necrosis factor-α factor (LITAF) cause the autosomal dominant inherited peripheral neuropathy, Charcot-Marie-Tooth disease type 1C (CMT1C). LITAF encodes a 17 kDa protein containing an N-terminal proline-rich region followed by an evolutionarily-conserved C-terminal 'LITAF domain', which contains all reported CMT1C-associated pathogenic mutations. RESULTS Here, we report the first structural characterisation of LITAF using biochemical, cell biological, biophysical and NMR spectroscopic approaches. Our structural model demonstrates that LITAF is a monotopic zinc-binding membrane protein that embeds into intracellular membranes via a predicted hydrophobic, in-plane, helical anchor located within the LITAF domain. We show that specific residues within the LITAF domain interact with phosphoethanolamine (PE) head groups, and that the introduction of the V144M CMT1C-associated pathogenic mutation leads to protein aggregation in the presence of PE. CONCLUSIONS In addition to the structural characterisation of LITAF, these data lead us to propose that an aberrant LITAF-PE interaction on the surface of intracellular membranes contributes to the molecular pathogenesis that underlies this currently incurable disease.
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Affiliation(s)
- Anita K Ho
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Jane L Wagstaff
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Paul T Manna
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Lena Wartosch
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Seema Qamar
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK
| | - Elspeth F Garman
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Stefan M V Freund
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Rhys C Roberts
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus, Cambridge, CB2 0XY, UK.
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12
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Rajabally YA, Adams D, Latour P, Attarian S. Hereditary and inflammatory neuropathies: a review of reported associations, mimics and misdiagnoses. J Neurol Neurosurg Psychiatry 2016; 87:1051-60. [PMID: 27010614 DOI: 10.1136/jnnp-2015-310835] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 02/28/2016] [Indexed: 02/03/2023]
Abstract
Distinguishing between hereditary and inflammatory neuropathy is usually straightforward on clinical grounds with the help of a family history. There are nevertheless cases where the distinction is less clear. The advent of molecular genetics has in the past several years aided confirmatory diagnosis for an increasing proportion of patients with genetic neuropathy. Various reports have described associations of Charcot-Marie-Tooth disease with a suspected or confirmed inflammatory neuropathy occasionally responding to immunotherapy. Possible predisposition to an inflammatory component was suggested in a subset of patients. Such reports have, however, been relatively few in number, suggesting the rarity of such associations and of such a predisposition if it exists. There have been a number of publications detailing clinical presentations suggestive of inflammatory neuropathy in patients with a known or later proven genetic aetiology, and subsequently felt to be part of the phenotype rather than representing an association. A number of genetically mediated multisystemic diseases with neuropathy have otherwise been reported as mimicking chronic inflammatory demyelinating polyneuropathy (CIDP). The most common example is that of familial amyloid polyneuropathy, of particular concern for the clinician when misdiagnosed as CIDP, in view of the therapeutic implications. We review the literature on reported associations, mimics and misdiagnoses of hereditary and inflammatory neuropathy and attempt to determine a practical approach to the problem in clinical practice using clinical features, electrophysiology, histopathology and targeted early genetic testing. The issue of attempting immunomodulatory therapy is discussed in view of the published literature.
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Affiliation(s)
- Yusuf A Rajabally
- School of Life and Health Sciences, Aston Brain Centre, Aston University, Birmingham, UK Regional Neuromuscular Clinic, Queen Elizabeth Hospital, University Hospitals of Birmingham, Birmingham, UK
| | - David Adams
- Department of Neurology, National Reference Centre for FAP and other rare peripheral neuropathies (NNERf) APHP, CHU Bicêtre, HUPS, INSERM U1195, Université Paris Sud, Le Kremlin-Bicêtre, France FILNEMUS, Filière nationale des Maladies neuromusculaires, Marseille, France
| | - Philippe Latour
- Laboratoire de Neurogénétique Moléculaire, Groupe Hospitalier Est, Hospices Civils de Lyon, Lyon, France
| | - Shahram Attarian
- FILNEMUS, Filière nationale des Maladies neuromusculaires, Marseille, France Reference Centre for Neuromuscular Diseases and ALS, Centre Hospitalier Universitaire La Timone, Marseille, France Inserm UMR_S 910 Medical Genetics and Functional Genomics, Aix-Marseille University, Marseille, France
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13
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The Charcot Marie Tooth disease protein LITAF is a zinc-binding monotopic membrane protein. Biochem J 2016; 473:3965-3978. [PMID: 27582497 PMCID: PMC5095921 DOI: 10.1042/bcj20160657] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 08/31/2016] [Indexed: 01/11/2023]
Abstract
LITAF (LPS-induced TNF-activating factor) is an endosome-associated integral membrane protein important for multivesicular body sorting. Several mutations in LITAF cause autosomal-dominant Charcot Marie Tooth disease type 1C. These mutations map to a highly conserved C-terminal region, termed the LITAF domain, which includes a 22 residue hydrophobic sequence and flanking cysteine-rich regions that contain peptide motifs found in zinc fingers. Although the LITAF domain is thought to be responsible for membrane integration, the membrane topology of LITAF has not been established. Here, we have investigated whether LITAF is a tail-anchored (TA) membrane-spanning protein or monotopic membrane protein. When translated in vitro, LITAF integrates poorly into ER-derived microsomes compared with Sec61β, a bona fide TA protein. Furthermore, introduction of N-linked glycosylation reporters shows that neither the N-terminal nor C-terminal domains of LITAF translocate into the ER lumen. Expression in cells of an LITAF construct containing C-terminal glycosylation sites confirms that LITAF is not a TA protein in cells. Finally, an immunofluorescence-based latency assay showed that both the N- and C-termini of LITAF are exposed to the cytoplasm. Recombinant LITAF contains 1 mol/mol zinc, while mutation of predicted zinc-binding residues disrupts LITAF membrane association. Hence, we conclude that LITAF is a monotopic membrane protein whose membrane integration is stabilised by a zinc finger. The related human protein, CDIP1 (cell death involved p53 target 1), displays identical membrane topology, suggesting that this mode of membrane integration is conserved in LITAF family proteins.
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14
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Werheid F, Azzedine H, Zwerenz E, Bozkurt A, Moeller MJ, Lin L, Mull M, Häusler M, Schulz JB, Weis J, Claeys KG. Underestimated associated features in CMT neuropathies: clinical indicators for the causative gene? Brain Behav 2016; 6:e00451. [PMID: 27088055 PMCID: PMC4782242 DOI: 10.1002/brb3.451] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/25/2016] [Accepted: 02/02/2016] [Indexed: 12/15/2022] Open
Abstract
INTRODUCTION Charcot-Marie-Tooth neuropathy (CMT) is a genetically heterogeneous group of peripheral neuropathies. In addition to the classical clinical phenotype, additional features can occur. METHODS We studied a wide range of additional features in a cohort of 49 genetically confirmed CMT patients and performed a systematic literature revision. RESULTS Patients harbored a PMP22 gene alteration (n = 28) or a mutation in MPZ (n = 11), GJB1 (n = 4), LITAF (n = 2), MFN2 (n = 2), INF2 (n = 1), NEFL (n = 1). We identified four novel mutations (3 MPZ, 1 GJB1). A total of 88% presented at least one additional feature. In MPZ patients, we detected hypertrophic nerve roots in 3/4 cases that underwent spinal MRI, and pupillary abnormalities in 27%. In our cohort, restless legs syndrome (RLS) was present in 18%. We describe for the first time RLS associated with LITAF or MFN2 and predominant upper limb involvement with LITAF. Cold-induced hand cramps occurred in 10% (PMP22,MPZ,MFN2), and autonomous nervous system involvement in 18% (PMP22,MPZ, LITAF,MFN2). RLS and respiratory insufficiency were mostly associated with severe neuropathy, and pupillary abnormalities with mild to moderate neuropathy. CONCLUSIONS In CMT patients, additional features occur frequently. Some of them might be helpful in orienting genetic diagnosis. Our data broaden the clinical spectrum and genotype-phenotype associations with CMT.
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Affiliation(s)
- Friederike Werheid
- Department of Neurology University Hospital RWTH Aachen Aachen Germany; Institute of Neuropathology University Hospital RWTH Aachen Aachen Germany
| | - Hamid Azzedine
- Institute of Neuropathology University Hospital RWTH Aachen Aachen Germany
| | - Eva Zwerenz
- Department of Neurology University Hospital RWTH Aachen Aachen Germany; Institute of Neuropathology University Hospital RWTH Aachen Aachen Germany
| | - Ahmet Bozkurt
- Department of Plastic and Reconstructive Surgery Hand Surgery-Burn Center University Hospital RWTH Aachen Aachen Germany; Department of Plastic & Aesthetic, Reconstructive & Hand Surgery Center for Reconstructive Microsurgery and Peripheral Nerve Surgery (ZEMPEN) Agaplesion Markus Hospital Frankfurt am Main Germany
| | - Marcus J Moeller
- Section Immunology and Nephrology Department of Internal Medicine University Hospital RWTH Aachen Aachen Germany
| | - Lilian Lin
- Department of Neurology University Hospital RWTH Aachen Aachen Germany; Institute of Neuropathology University Hospital RWTH Aachen Aachen Germany
| | - Michael Mull
- Department of Neuroradiology University Hospital RWTH Aachen Aachen Germany
| | - Martin Häusler
- Division of Neuropediatrics and Social Pediatrics Department of Pediatrics University Hospital RWTH Aachen Aachen Germany
| | - Jörg B Schulz
- Department of Neurology University Hospital RWTH Aachen Aachen Germany; JARA - Translational Brain Medicine Aachen Germany
| | - Joachim Weis
- Institute of Neuropathology University Hospital RWTH Aachen Aachen Germany
| | - Kristl G Claeys
- Department of Neurology University Hospital RWTH Aachen Aachen Germany; Institute of Neuropathology University Hospital RWTH Aachen Aachen Germany; Department of Neurology University Hospitals Leuven and University of Leuven (KU Leuven) Leuven Belgium
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15
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Hoyle JC, Isfort MC, Roggenbuck J, Arnold WD. The genetics of Charcot-Marie-Tooth disease: current trends and future implications for diagnosis and management. APPLICATION OF CLINICAL GENETICS 2015; 8:235-43. [PMID: 26527893 PMCID: PMC4621202 DOI: 10.2147/tacg.s69969] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Charcot–Marie–Tooth (CMT) disease is the most common hereditary polyneuropathy and is classically associated with an insidious onset of distal predominant motor and sensory loss, muscle wasting, and pes cavus. Other forms of hereditary neuropathy, including sensory predominant or motor predominant forms, are sometimes included in the general classification of CMT, but for the purpose of this review, we will focus primarily on the forms associated with both sensory and motor deficits. CMT has a great deal of genetic heterogeneity, leading to diagnostic considerations that are still rapidly evolving for this disorder. Clinical features, inheritance pattern, gene mutation frequencies, and electrodiagnostic features all are helpful in formulating targeted testing algorithms in practical clinical settings, but these still have shortcomings. Next-generation sequencing (NGS), combined with multigene testing panels, is increasing the sensitivity and efficiency of genetic testing and is quickly overtaking targeted testing strategies. Currently, multigene panel testing and NGS can be considered first-line in many circumstances, although obtaining initial targeted testing for the PMP22 duplication in CMT patients with demyelinating conduction velocities is still a reasonable strategy. As technology improves and cost continues to fall, targeted testing will be completely replaced by multigene NGS panels that can detect the full spectrum of CMT mutations. Nevertheless, clinical acumen is still necessary given the variants of uncertain significance encountered with NGS. Despite the current limitations, the genetic diagnosis of CMT is critical for accurate prognostication, genetic counseling, and in the future, specific targeted therapies. Although whole exome and whole genome sequencing strategies have the power to further elucidate the genetics of CMT, continued technological advances are needed.
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Affiliation(s)
- J Chad Hoyle
- Department of Neurology, Division of Neuromuscular Disorders, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Michael C Isfort
- Department of Neurology, Division of Neuromuscular Disorders, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jennifer Roggenbuck
- Department of Neurology, Division of Neuromuscular Disorders, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Internal Medicine, Division of Human Genetics, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - W David Arnold
- Department of Neurology, Division of Neuromuscular Disorders, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Physical Medicine and Rehabilitation, The Ohio State University Wexner Medical Center, Columbus, OH, USA ; Department of Neuroscience, The Ohio State University Wexner Medical Center, Columbus, OH, USA
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16
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Dysregulated Inflammatory Signaling upon Charcot-Marie-Tooth Type 1C Mutation of SIMPLE Protein. Mol Cell Biol 2015; 35:2464-78. [PMID: 25963657 DOI: 10.1128/mcb.00300-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Endosomal trafficking is a key mechanism to modulate signal propagation and cross talk. Ubiquitin adaptors, along with endosomal sorting complex required for transport (ESCRT) complexes, are also integrated to terminate ligand-receptor activation in late endosomes and multivesicular bodies (MVBs). Within these pathways, we recently demonstrated that the protein SIMPLE is a novel player in MVB regulation. SIMPLE is also clinically important and its mutation accounts for the Charcot-Marie-Tooth type 1C (CMT1C) disease. MVB defects of mutation and deletion of SIMPLE, however, are distinct. Here, we show that MVB defects found in mutation but not deletion of SIMPLE lead to impaired turnover and accumulation of ESCRT-0 protein Hrs punctain late endosomes. We further uncover increased colocalization of ubiquitin ligase TRAF6 and Hrs in late endosomes. Upon stimulation with interkeukin-1 or transforming growth factor , prolonged activation of p38 kinase/JNK is detected, while nuclear accumulation of NF-κB and phosphorylation of SMAD2 is reduced with CMT1C mutation. The aberrant kinetics we observed in inflammatory signaling may contribute to increased tumor susceptibility and changes in the levels of chemokines/cytokines that result from CMT1C mutation. We propose that altered endosomal trafficking due to malformations of MVBs and subsequent atypical signaling kinetic may account for a toxic gain of function in CMT1C pathogenesis.
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17
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Watson JA, Bhattacharyya BJ, Vaden JH, Wilson JA, Icyuz M, Howard AD, Phillips E, DeSilva TM, Siegal GP, Bean AJ, King GD, Phillips SE, Miller RJ, Wilson SM. Motor and Sensory Deficits in the teetering Mice Result from Mutation of the ESCRT Component HGS. PLoS Genet 2015; 11:e1005290. [PMID: 26115514 PMCID: PMC4482608 DOI: 10.1371/journal.pgen.1005290] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 05/18/2015] [Indexed: 11/18/2022] Open
Abstract
Neurons are particularly vulnerable to perturbations in endo-lysosomal transport, as several neurological disorders are caused by a primary deficit in this pathway. In this report, we used positional cloning to show that the spontaneously occurring neurological mutation teetering (tn) is a single nucleotide substitution in hepatocyte growth factor-regulated tyrosine kinase substrate (Hgs/Hrs), a component of the endosomal sorting complex required for transport (ESCRT). The tn mice exhibit hypokenesis, muscle weakness, reduced muscle size and early perinatal lethality by 5-weeks of age. Although HGS has been suggested to be essential for the sorting of ubiquitinated membrane proteins to the lysosome, there were no alterations in receptor tyrosine kinase levels in the central nervous system, and only a modest decrease in tropomyosin receptor kinase B (TrkB) in the sciatic nerves of the tn mice. Instead, loss of HGS resulted in structural alterations at the neuromuscular junction (NMJ), including swellings and ultra-terminal sprouting at motor axon terminals and an increase in the number of endosomes and multivesicular bodies. These structural changes were accompanied by a reduction in spontaneous and evoked release of acetylcholine, indicating a deficit in neurotransmitter release at the NMJ. These deficits in synaptic transmission were associated with elevated levels of ubiquitinated proteins in the synaptosome fraction. In addition to the deficits in neuronal function, mutation of Hgs resulted in both hypermyelinated and dysmyelinated axons in the tn mice, which supports a growing body of evidence that ESCRTs are required for proper myelination of peripheral nerves. Our results indicate that HGS has multiple roles in the nervous system and demonstrate a previously unanticipated requirement for ESCRTs in the maintenance of synaptic transmission. Endocytic trafficking involves the internalization, endosomal sorting and lysosomal degradation of cell surface cargo. Many factors involved in endosomal sorting in mammalian cells have been identified, and mutations in these components are associated with a variety of neurological disorders. While the function of endosomal sorting components has been intensely studied in immortalized cell lines, it is not known what role these factors play in endosomal sorting in the nervous system. In this study, we show that the teetering (tn) gene encodes the hepatocytegrowth factor regulated tyrosine kinasesubstrate (Hgs), a core component of the endosomal sorting pathway. The tn mice exhibit several signs of motor neuron disease, including reduced muscle mass, muscle weakness and motor abnormalities. Although HGS is predicted to be required for the lysosomal degradation of receptor tyrosine kinases, there was no change in the levels of receptor tyrosine kinases in the spinal cords of the tn mice. Instead, we found that HGS is required for synaptic transmission at the neuromuscular junction and for the proper myelination of the peripheral nervous system.
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Affiliation(s)
- Jennifer A. Watson
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Bula J. Bhattacharyya
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Evanston, Illinois, United States of America
| | - Jada H. Vaden
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Julie A. Wilson
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Mert Icyuz
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Alan D. Howard
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Edward Phillips
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Tara M. DeSilva
- Department of Physical Medicine and Rehabilitation, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Gene P. Siegal
- Departments of Pathology, Surgery and Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Andrew J. Bean
- Department of Neurobiology and Anatomy and Graduate School of Biomedical Sciences, The University of Texas Health Science Center at Houston, Houston, Texas, United States of America
- Division of Pediatrics, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, United States of America
| | - Gwendalyn D. King
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Scott E. Phillips
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
| | - Richard J. Miller
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Evanston, Illinois, United States of America
| | - Scott M. Wilson
- Department of Neurobiology, University of Alabama at Birmingham, Evelyn F. McKnight Brain Institute, Civitan International Research Center, Birmingham, Alabama, United States of America
- * E-mail:
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18
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Potulska-Chromik A, Sinkiewicz-Darol E, Ryniewicz B, Lipowska M, Kabzińska D, Kochański A, Kostera-Pruszczyk A. Clinical, electrophysiological, and molecular findings in early onset hereditary neuropathy with liability to pressure palsy. Muscle Nerve 2014; 50:914-8. [DOI: 10.1002/mus.24250] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2014] [Indexed: 01/11/2023]
Affiliation(s)
- Anna Potulska-Chromik
- Department of Neurology; Medical University of Warsaw; Banacha 1a Street 02-097 Warsaw Poland
| | - Elena Sinkiewicz-Darol
- Neuromuscular Unit, Mossakowski Medical Research Centre, Polish Academy of Sciences; Warsaw Poland
| | - Barbara Ryniewicz
- Department of Neurology; Medical University of Warsaw; Banacha 1a Street 02-097 Warsaw Poland
| | - Marta Lipowska
- Department of Neurology; Medical University of Warsaw; Banacha 1a Street 02-097 Warsaw Poland
| | - Dagmara Kabzińska
- Neuromuscular Unit, Mossakowski Medical Research Centre, Polish Academy of Sciences; Warsaw Poland
| | - Andrzej Kochański
- Neuromuscular Unit, Mossakowski Medical Research Centre, Polish Academy of Sciences; Warsaw Poland
| | - Anna Kostera-Pruszczyk
- Department of Neurology; Medical University of Warsaw; Banacha 1a Street 02-097 Warsaw Poland
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19
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Kumar CV, Swetha RG, Ramaiah S, Anbarasu A. Tryptophan to Glycine mutation in the position 116 leads to protein aggregation and decreases the stability of the LITAF protein. J Biomol Struct Dyn 2014; 33:1695-709. [DOI: 10.1080/07391102.2014.968211] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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20
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A novel LITAF/SIMPLE mutation within a family with a demyelinating form of Charcot–Marie–Tooth disease. J Neurol Sci 2014; 343:183-6. [DOI: 10.1016/j.jns.2014.05.029] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/09/2014] [Accepted: 05/13/2014] [Indexed: 11/22/2022]
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21
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Mathis S, Corcia P, Tazir M, Camu W, Magdelaine C, Latour P, Biberon J, Guennoc AM, Richard L, Magy L, Funalot B, Vallat JM. Peripheral Myelin Protein 22 gene duplication with atypical presentations: A new example of the wide spectrum of Charcot-Marie-Tooth 1A disease. Neuromuscul Disord 2014; 24:524-8. [DOI: 10.1016/j.nmd.2014.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Revised: 03/14/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
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22
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Luigetti M, Fabrizi GM, Taioli F, Del Grande A, Lo Monaco M. A novel LITAF/SIMPLE variant within a family with minimal demyelinating Charcot–Marie–Tooth disease. Neurol Sci 2014; 35:2005-7. [DOI: 10.1007/s10072-014-1833-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 05/08/2014] [Indexed: 11/28/2022]
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23
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Zhu H, Guariglia S, Yu RYL, Li W, Brancho D, Peinado H, Lyden D, Salzer J, Bennett C, Chow CW. Mutation of SIMPLE in Charcot-Marie-Tooth 1C alters production of exosomes. Mol Biol Cell 2013; 24:1619-37, S1-3. [PMID: 23576546 PMCID: PMC3667717 DOI: 10.1091/mbc.e12-07-0544] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mutations in the protein SIMPLE account for the rare autosomal-dominant demyelination in type 1C CMT patients (CMT1C). SIMPLE plays a role in the production of exosomes. Dysregulated endosomal trafficking and changes in exosome-mediated intercellular communications might account for CMT1C molecular pathogenesis. Charcot–Marie–Tooth (CMT) disease is an inherited neurological disorder. Mutations in the small integral membrane protein of the lysosome/late endosome (SIMPLE) account for the rare autosomal-dominant demyelination in CMT1C patients. Understanding the molecular basis of CMT1C pathogenesis is impeded, in part, by perplexity about the role of SIMPLE, which is expressed in multiple cell types. Here we show that SIMPLE resides within the intraluminal vesicles of multivesicular bodies (MVBs) and inside exosomes, which are nanovesicles secreted extracellularly. Targeting of SIMPLE to exosomes is modulated by positive and negative regulatory motifs. We also find that expression of SIMPLE increases the number of exosomes and secretion of exosome proteins. We engineer a point mutation on the SIMPLE allele and generate a physiological mouse model that expresses CMT1C-mutated SIMPLE at the endogenous level. We find that CMT1C mouse primary embryonic fibroblasts show decreased number of exosomes and reduced secretion of exosome proteins, in part due to improper formation of MVBs. CMT1C patient B cells and CMT1C mouse primary Schwann cells show similar defects. Together the data indicate that SIMPLE regulates the production of exosomes by modulating the formation of MVBs. Dysregulated endosomal trafficking and changes in the landscape of exosome-mediated intercellular communications may place an overwhelming burden on the nervous system and account for CMT1C molecular pathogenesis.
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Affiliation(s)
- Hong Zhu
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY 10461, USA
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24
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Chin LS, Lee SM, Li L. SIMPLE: A new regulator of endosomal trafficking and signaling in health and disease. Commun Integr Biol 2013; 6:e24214. [PMID: 23713142 PMCID: PMC3656027 DOI: 10.4161/cib.24214] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 03/06/2013] [Indexed: 12/29/2022] Open
Abstract
SIMPLE, also known as LITAF, EET1 and PIG7, was originally identified based on its transcriptional upregulation by estrogen, p53, lipopolysaccharide or a microbial cell-wall component. Missense mutations in SIMPLE cause Charcot-Marie-Tooth disease (CMT), and altered SIMPLE expression is associated with cancer, obesity and inflammatory bowel diseases. Despite increasing evidence linking SIMPLE to human diseases, the biological function of SIMPLE is unknown and the pathogenic mechanism of SIMPLE mutations remains elusive. Our recent study reveals that SIMPLE is a functional partner of the endosomal sorting complex required for transport (ESCRT) machinery in the regulation of endosome-to-lysosome trafficking and intracellular signaling. Our results indicate that CMT-linked SIMPLE mutants are loss-of-function mutants which act dominantly to impair endosomal trafficking and signaling attenuation. We propose that endosomal trafficking and signaling dysregulation is a key pathogenic mechanism in CMT and other diseases that involve SIMPLE dysfunction.
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Affiliation(s)
- Lih-Shen Chin
- Department of Pharmacology; Emory University School of Medicine; Atlanta, GA USA
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Lee SM, Sha D, Mohammed AA, Asress S, Glass JD, Chin LS, Li L. Motor and sensory neuropathy due to myelin infolding and paranodal damage in a transgenic mouse model of Charcot-Marie-Tooth disease type 1C. Hum Mol Genet 2013; 22:1755-70. [PMID: 23359569 DOI: 10.1093/hmg/ddt022] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Charcot-Marie-Tooth disease type 1C (CMT1C) is a dominantly inherited motor and sensory neuropathy. Despite human genetic evidence linking missense mutations in SIMPLE to CMT1C, the in vivo role of CMT1C-linked SIMPLE mutations remains undetermined. To investigate the molecular mechanism underlying CMT1C pathogenesis, we generated transgenic mice expressing either wild-type or CMT1C-linked W116G human SIMPLE. Mice expressing mutant, but not wild type, SIMPLE develop a late-onset motor and sensory neuropathy that recapitulates key clinical features of CMT1C disease. SIMPLE mutant mice exhibit motor and sensory behavioral impairments accompanied by decreased motor and sensory nerve conduction velocity and reduced compound muscle action potential amplitude. This neuropathy phenotype is associated with focally infolded myelin loops that protrude into the axons at paranodal regions and near Schmidt-Lanterman incisures of peripheral nerves. We find that myelin infolding is often linked to constricted axons with signs of impaired axonal transport and to paranodal defects and abnormal organization of the node of Ranvier. Our findings support that SIMPLE mutation disrupts myelin homeostasis and causes peripheral neuropathy via a combination of toxic gain-of-function and dominant-negative mechanisms. The results from this study suggest that myelin infolding and paranodal damage may represent pathogenic precursors preceding demyelination and axonal degeneration in CMT1C patients.
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Affiliation(s)
- Samuel M Lee
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Lee SM, Chin LS, Li L. Charcot-Marie-Tooth disease-linked protein SIMPLE functions with the ESCRT machinery in endosomal trafficking. ACTA ACUST UNITED AC 2012; 199:799-816. [PMID: 23166352 PMCID: PMC3514783 DOI: 10.1083/jcb.201204137] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
SIMPLE functions with the ESCRT machinery to promote endosome-to-lysosome trafficking, and this function is impaired by Charcot-Marie-Tooth disease–associated mutations. Mutations in small integral membrane protein of lysosome/late endosome (SIMPLE) cause autosomal dominant, Charcot-Marie-Tooth disease (CMT) type 1C. The cellular function of SIMPLE is unknown and the pathogenic mechanism of SIMPLE mutations remains elusive. Here, we report that SIMPLE interacted and colocalized with endosomal sorting complex required for transport (ESCRT) components STAM1, Hrs, and TSG101 on early endosomes and functioned with the ESCRT machinery in the control of endosome-to-lysosome trafficking. Our analyses revealed that SIMPLE was required for efficient recruitment of ESCRT components to endosomal membranes and for regulating endosomal trafficking and signaling attenuation of ErbB receptors. We found that the ability of SIMPLE to regulate ErbB trafficking and signaling was impaired by CMT-linked SIMPLE mutations via a loss-of-function, dominant-negative mechanism, resulting in prolonged activation of ERK1/2 signaling. Our findings indicate a function of SIMPLE as a regulator of endosomal trafficking and provide evidence linking dysregulated endosomal trafficking to CMT pathogenesis.
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Affiliation(s)
- Samuel M Lee
- Department of Pharmacology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, GA 30322, USA
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Somandin C, Gerber D, Pereira JA, Horn M, Suter U. LITAF (SIMPLE) regulates Wallerian degeneration after injury but is not essential for peripheral nerve development and maintenance: implications for Charcot-Marie-Tooth disease. Glia 2012; 60:1518-28. [PMID: 22729949 DOI: 10.1002/glia.22371] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/23/2012] [Indexed: 01/05/2023]
Abstract
Missense mutations affecting the LITAF gene (also known as SIMPLE) lead to the dominantly inherited peripheral neuropathy Charcot-Marie-Tooth disease type 1C (CMT1C). In this study, we sought to determine the requirement of Litaf function in peripheral nerves, the only known affected tissue in CMT1C. We reasoned that this knowledge is a prerequisite for a thorough understanding of the underlying disease mechanism with regard to potential contributions by Litaf loss of function. In addition, we anticipated to obtain valuable information about the basic function of the Litaf protein in peripheral nerves. To address these issues, we generated mice without Litaf expression using gene disruption in embryonic stem cells and analyzed Litaf-deficient peripheral nerves during development, in maintenance, and after injury. Our results show that Litaf function is not absolutely required for peripheral nerve development and maintenance. In injured nerves, however, we found that lack of Litaf led to increased numbers of macrophages during Wallerian degeneration, accelerated myelin destruction, and the emergence of more axonal sprouts. Consistent with these data, the migration of Litaf-deficient macrophages was increased upon chemokine stimulation. We conclude that loss of Litaf function is unlikely to be a major contributor to CMT1C, but modulating effects of macrophages need to be considered in the etiology of the disease.
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Affiliation(s)
- Christian Somandin
- Department of Biology, Institute of Molecular Health Sciences, Cell Biology, Swiss Federal Institute of Technology, ETH Zurich, CH-8093 Zurich, Switzerland
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Yger M, Stojkovic T, Tardieu S, Maisonobe T, Brice A, Echaniz-Laguna A, Alembik Y, Girard S, Cazeneuve C, LeGuern E, Dubourg O. Characteristics of clinical and electrophysiological pattern of Charcot-Marie-Tooth 4C. J Peripher Nerv Syst 2012; 17:112-22. [DOI: 10.1111/j.1529-8027.2012.00382.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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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Lee SM, Olzmann JA, Chin LS, Li L. Mutations associated with Charcot-Marie-Tooth disease cause SIMPLE protein mislocalization and degradation by the proteasome and aggresome-autophagy pathways. J Cell Sci 2011; 124:3319-31. [PMID: 21896645 DOI: 10.1242/jcs.087114] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mutations in SIMPLE cause an autosomal dominant, demyelinating form of peripheral neuropathy termed Charcot-Marie-Tooth disease type 1C (CMT1C), but the pathogenic mechanisms of these mutations remain unknown. Here, we report that SIMPLE is an early endosomal membrane protein that is highly expressed in the peripheral nerves and Schwann cells. Our analysis has identified a transmembrane domain (TMD) embedded within the cysteine-rich (C-rich) region that anchors SIMPLE to the membrane, and suggests that SIMPLE is a post-translationally inserted, C-tail-anchored membrane protein. We found that CMT1C-linked pathogenic mutations are clustered within or around the TMD of SIMPLE and that these mutations cause mislocalization of SIMPLE from the early endosome membrane to the cytosol. The CMT1C-associated SIMPLE mutant proteins are unstable and prone to aggregation, and they are selectively degraded by both the proteasome and aggresome-autophagy pathways. Our findings suggest that SIMPLE mutations cause CMT1C peripheral neuropathy by a combination of loss-of-function and toxic gain-of-function mechanisms, and highlight the importance of both the proteasome and autophagy pathways in the clearance of CMT1C-associated mutant SIMPLE proteins.
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Affiliation(s)
- Samuel M Lee
- Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA
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Murphy SM, Laurá M, Blake J, Polke J, Bremner F, Reilly MM. Conduction block and tonic pupils in Charcot-Marie-Tooth disease caused by a myelin protein zero p.Ile112Thr mutation. Neuromuscul Disord 2011; 21:223-6. [DOI: 10.1016/j.nmd.2010.12.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 11/26/2010] [Accepted: 12/21/2010] [Indexed: 11/29/2022]
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