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Della Marina A, Hentschel A, Czech A, Schara-Schmidt U, Preusse C, Laner A, Abicht A, Ruck T, Weis J, Choueiri C, Lochmüller H, Kölbel H, Roos A. Novel Genetic and Biochemical Insights into the Spectrum of NEFL-Associated Phenotypes. J Neuromuscul Dis 2024; 11:625-645. [PMID: 38578900 PMCID: PMC11091643 DOI: 10.3233/jnd-230230] [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] [Accepted: 03/06/2024] [Indexed: 04/07/2024]
Abstract
Background NEFL encodes for the neurofilament light chain protein. Pathogenic variants in NEFL cause demyelinating, axonal and intermediate forms of Charcot-Marie-Tooth disease (CMT) which present with a varying degree of severity and somatic mutations have not been described yet. Currently, 34 different CMT-causing pathogenic variants in NEFL in 174 patients have been reported. Muscular involvement was also described in CMT2E patients mostly as a secondary effect. Also, there are a few descriptions of a primary muscle vulnerability upon pathogenic NEFL variants. Objectives To expand the current knowledge on the genetic landscape, clinical presentation and muscle involvement in NEFL-related neurological diseases by retrospective case study and literature review. Methods We applied in-depth phenotyping of new and already reported cases, molecular genetic testing, light-, electron- and Coherent Anti-Stokes Raman Scattering-microscopic studies and proteomic profiling in addition to in silico modelling of NEFL-variants. Results We report on a boy with a muscular phenotype (weakness, myalgia and cramps, Z-band alterations and mini-cores in some myofibers) associated with the heterozygous p.(Phe104Val) NEFL-variant, which was previously described in a neuropathy case. Skeletal muscle proteomics findings indicated affection of cytoskeletal proteins. Moreover, we report on two further neuropathic patients (16 years old girl and her father) both carrying the heterozygous p.(Pro8Ser) variant, which has been identified as 15% somatic mosaic in the father. While the daughter presented with altered neurophysiology,neurogenic clump feet and gait disturbances, the father showed clinically only feet deformities. As missense variants affecting proline at amino acid position 8 are leading to neuropathic manifestations of different severities, in silico modelling of these different amino acid substitutions indicated variable pathogenic impact correlating with disease onset. Conclusions Our findings provide new morphological and biochemical insights into the vulnerability of denervated muscle (upon NEFL-associated neuropathy) as well as novel genetic findings expanding the current knowledge on NEFL-related neuromuscular phenotypes and their clinical manifestations. Along this line, our data show that even subtle expression of somatic NEFL variants can lead to neuromuscular symptoms.
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Affiliation(s)
- Adela Della Marina
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Andreas Hentschel
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany
| | - Artur Czech
- Leibniz-Institut für Analytische Wissenschaften -ISAS- e.V., Dortmund, Germany
| | - Ulrike Schara-Schmidt
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Corinna Preusse
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health (BIH), Berlin, Germany
| | | | - Angela Abicht
- Medical Genetics Center, Munich, Germany
- Friedrich-Baur Institute, Ludwig Maximilian University, Munich, Germany
| | - Tobias Ruck
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Catherine Choueiri
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
| | - Hanns Lochmüller
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
- Brain and Mind Research Institute, University of Ottawa, Ottawa, Canada
| | - Heike Kölbel
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
| | - Andreas Roos
- Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro- and Behavioral Sciences, University Duisburg-Essen, Essen, Germany
- Department of Neurology, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
- Children’s Hospital of Eastern Ontario Research Institute, Ottawa, ON, Canada
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Kotaich F, Caillol D, Bomont P. Neurofilaments in health and Charcot-Marie-Tooth disease. Front Cell Dev Biol 2023; 11:1275155. [PMID: 38164457 PMCID: PMC10758125 DOI: 10.3389/fcell.2023.1275155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/02/2023] [Indexed: 01/03/2024] Open
Abstract
Neurofilaments (NFs) are the most abundant component of mature neurons, that interconnect with actin and microtubules to form the cytoskeleton. Specifically expressed in the nervous system, NFs present the particularity within the Intermediate Filament family of being formed by four subunits, the neurofilament light (NF-L), medium (NF-M), heavy (NF-H) proteins and α-internexin or peripherin. Here, we review the current knowledge on NF proteins and neurofilaments, from their domain structures and their model of assembly to the dynamics of their transport and degradation along the axon. The formation of the filament and its behaviour are regulated by various determinants, including post-transcriptional (miRNA and RBP proteins) and post-translational (phosphorylation and ubiquitination) modifiers. Altogether, the complex set of modifications enable the neuron to establish a stable but elastic NF array constituting the structural scaffold of the axon, while permitting the local expression of NF proteins and providing the dynamics necessary to fulfil local demands and respond to stimuli and injury. Thus, in addition to their roles in mechano-resistance, radial axonal outgrowth and nerve conduction, NFs control microtubule dynamics, organelle distribution and neurotransmission at the synapse. We discuss how the studies of neurodegenerative diseases with NF aggregation shed light on the biology of NFs. In particular, the NEFL and NEFH genes are mutated in Charcot-Marie-Tooth (CMT) disease, the most common inherited neurological disorder of the peripheral nervous system. The clinical features of the CMT forms (axonal CMT2E, CMT2CC; demyelinating CMT1F; intermediate I-CMT) with symptoms affecting the central nervous system (CNS) will allow us to further investigate the physiological roles of NFs in the brain. Thus, NF-CMT mouse models exhibit various degrees of sensory-motor deficits associated with CNS symptoms. Cellular systems brought findings regarding the dominant effect of NF-L mutants on NF aggregation and transport, although these have been recently challenged. Neurofilament detection without NF-L in recessive CMT is puzzling, calling for a re-examination of the current model in which NF-L is indispensable for NF assembly. Overall, we discuss how the fundamental and translational fields are feeding each-other to increase but also challenge our knowledge of NF biology, and to develop therapeutic avenues for CMT and neurodegenerative diseases with NF aggregation.
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Affiliation(s)
| | | | - Pascale Bomont
- ERC team, NeuroMyoGene Institute-Pathophysiology and Genetics of Neuron and Muscle, Inserm U1315, CNRS UMR5261, University of Lyon 1, Lyon, France
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Park HM, Le L, Nguyen TT, Nam KH, Ordureau A, Lee JE, Nguyen TV. The CRL3 gigaxonin ubiquitin ligase-USP15 pathway governs the destruction of neurofilament proteins. Proc Natl Acad Sci U S A 2023; 120:e2306395120. [PMID: 37903270 PMCID: PMC10636361 DOI: 10.1073/pnas.2306395120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 09/20/2023] [Indexed: 11/01/2023] Open
Abstract
Giant axonal neuropathy (GAN) is caused by mutations in the GAN gene encoding for gigaxonin (GIG), which functions as an adaptor of the CUL3-RBX1-GIG (CRL3GIG) E3 ubiquitin ligase complex. The pathological hallmark of GAN is characterized by the accumulation of densely packed neurofilaments (NFs) in the axons. However, there are fundamental knowledge gaps in our understanding of the molecular mechanisms by which the ubiquitin-proteasome system controls the homeostasis of NF proteins. Recently, the deubiquitylating enzyme USP15 was reported to play a crucial role in regulating ubiquitylation and proteasomal degradation of CRL4CRBN substrate proteins. Here, we report that the CRL3GIG-USP15 pathway governs the destruction of NF proteins NEFL and INA. We identified a specific degron called NEFLL12 degron for CRL3GIG. Notably, mutations in the C-terminal Kelch domain of GIG, represented by L309R, R545C, and C570Y, disrupted the binding of GIG to NEFL and INA, leading to the accumulation of these NF proteins. This accounts for the loss-of-function mutations in GAN patients. In addition to regulating NFs, CRL3GIG also controls actin filaments by directly targeting actin-filament-binding regulatory proteins TPM1, TPM2, TAGLN, and CNN2 for proteasomal degradation. Thus, our findings broadly impact the field by providing fundamental mechanistic insights into regulating extremely long-lived NF proteins NEFL and INA by the CRL3GIG-USP15 pathway and offering previously unexplored therapeutic opportunities to treat GAN patients and other neurodegenerative diseases by explicitly targeting downstream substrates of CRL3GIG.
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Affiliation(s)
- Hyoung-Min Park
- Biometrology Group, Korea Research Institute of Standards and Science, Daejeon34113, Korea
| | - Ly Le
- Division of Quantum Simulation and Optimization, SandboxAQ, New York, NY10591
| | - Thao T. Nguyen
- Gehrke Proteomics Center, Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO65211
| | - Ki Hong Nam
- Cell Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY10065
| | - Alban Ordureau
- Cell Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY10065
| | - J. Eugene Lee
- Biometrology Group, Korea Research Institute of Standards and Science, Daejeon34113, Korea
| | - Thang Van Nguyen
- Center for Precision Medicine, Department of Medicine, University of Missouri, Columbia, MO65212
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Lei L, Xiaobo L, Zhiqiang L, Yongzhi X, Shunxiang H, Huadong Z, Beisha T, Ruxu Z. Genotype-phenotype characteristics and baseline natural history of Chinese myelin protein zero gene related neuropathy patients. Eur J Neurol 2023; 30:1069-1079. [PMID: 36692866 DOI: 10.1111/ene.15700] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/24/2022] [Accepted: 12/30/2022] [Indexed: 01/25/2023]
Abstract
BACKGROUND AND PURPOSE The aim was to characterize the phenotypic and genotypic features of myelin protein zero (MPZ) related neuropathy and provide baseline data for longitudinal natural history studies or drug clinical trials. METHOD Clinical, neurophysiological and genetic data of 37 neuropathy patients with MPZ mutations were retrospectively collected. RESULTS Nineteen different MPZ mutations in 23 unrelated neuropathy families were detected, and the frequency of MPZ mutations was 5.84% in total. Mutations c.103_104InsTGGTTTACACCG, c.513dupG, c.521_557del and c.696_699delCAGT had not been reported previously. Hot spot mutation p.Thr124Met was detected in four unrelated families, and seven patients carried de novo mutations. The onset age indicated a bimodal distribution: prominent clustering in the first and fourth decades. The infantile-onset group included 12 families, the childhood-onset group consisted of two families and the adult-onset group included nine families. The Charcot-Marie-Tooth Disease Neuropathy Score ranged from 3 to 25 with a mean value of 15.85 ± 5.88. Mutations that changed the cysteine residue (p.Arg98Cys, p.Cys127Trp, p.Ser140Cys and p.Cys127Arg) in the extracellular region were more likely to cause severe early-onset Charcot-Marie-Tooth disease type 1B (CMT1B) or Dejerine-Sottas syndrome. Nonsense-mediated mRNA decay mutations p.Asp35delInsVVYTD, p.Leu174Argfs*66 and p.Leu172Alafs*63 were related to severe infantile-onset CMT1B or Dejerine-Sottas syndrome; however, mutation p.Val232Valfs*19 was associated with a relatively milder childhood-onset CMT1 phenotype. CONCLUSION Four novel MPZ mutations are reported that expand the genetic spectrum. De novo mutations accounted for 30.4% and were most related to a severe infantile-onset phenotype. Genetic and clinical data from this cohort will provide the baseline data necessary for clinical trials and natural history studies.
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Affiliation(s)
- Liu Lei
- Health Management Center, Third Xiangya Hospital, Central South University, Changsha, China
| | - Li Xiaobo
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha, China
| | - Lin Zhiqiang
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha, China
| | - Xie Yongzhi
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha, China
| | - Huang Shunxiang
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha, China
| | - Zhao Huadong
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha, China
| | - Tang Beisha
- Department of Neurology, Xiangya Hospital, Central South University, Changsha, China
| | - Zhang Ruxu
- Department of Neurology, Third Xiangya Hospital, Central South University, Changsha, China
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Huynh DT, Hu J, Schneider JR, Tsolova KN, Soderblom EJ, Watson AJ, Chi JT, Evans CS, Boyce M. O-GlcNAcylation regulates neurofilament-light assembly and function and is perturbed by Charcot-Marie-Tooth disease mutations. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.22.529563. [PMID: 36865196 PMCID: PMC9980138 DOI: 10.1101/2023.02.22.529563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
The neurofilament (NF) cytoskeleton is critical for neuronal morphology and function. In particular, the neurofilament-light (NF-L) subunit is required for NF assembly in vivo and is mutated in subtypes of Charcot-Marie-Tooth (CMT) disease. NFs are highly dynamic, and the regulation of NF assembly state is incompletely understood. Here, we demonstrate that human NF-L is modified in a nutrient-sensitive manner by O-linked-β-N-acetylglucosamine (O-GlcNAc), a ubiquitous form of intracellular glycosylation. We identify five NF-L O-GlcNAc sites and show that they regulate NF assembly state. Interestingly, NF-L engages in O-GlcNAc-mediated protein-protein interactions with itself and with the NF component α-internexin, implying that O-GlcNAc is a general regulator of NF architecture. We further show that NF-L O-GlcNAcylation is required for normal organelle trafficking in primary neurons, underlining its functional significance. Finally, several CMT-causative NF-L mutants exhibit perturbed O-GlcNAc levels and resist the effects of O-GlcNAcylation on NF assembly state, indicating a potential link between dysregulated O-GlcNAcylation and pathological NF aggregation. Our results demonstrate that site-specific glycosylation regulates NF-L assembly and function, and aberrant NF O-GlcNAcylation may contribute to CMT and other neurodegenerative disorders.
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Affiliation(s)
- Duc T. Huynh
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jimin Hu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jordan R. Schneider
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Kalina N. Tsolova
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Erik J. Soderblom
- Proteomics and Metabolomics Shared Resource, Duke University School of Medicine, Durham, NC 27710, USA
| | - Abigail J. Watson
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Jen-Tsan Chi
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Chantell S. Evans
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Michael Boyce
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA
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Clinical and genetic characterization of NEFL-related neuropathy in Taiwan. J Formos Med Assoc 2023; 122:132-138. [PMID: 36031490 DOI: 10.1016/j.jfma.2022.08.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/20/2022] [Accepted: 08/09/2022] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Mutations in the neurofilament light polypeptide gene (NEFL) are an uncommon cause of Charcot-Marie-Tooth disease (CMT). The aim of this study is to elucidate the clinical characteristics and genetic spectrum of NEFL-related neuropathy in a Taiwanese CMT cohort. METHODS Mutational analysis of the coding regions of NEFL was performed by Sanger sequencing or targeted resequencing. Twenty-one patients from nine CMT pedigrees, identified from a cohort of 508 unrelated CMT patients, were found to have a NEFL mutation. Genetic, clinical and electrophysiological features were analyzed. RESULTS Six NEFL mutations were identified, including two novel ones (p.P8S, p.N98Y). NEFL p.E396K was the most common mutation, accounting for 33.3% of the patients in our cohort. All patients manifested sensorimotor polyneuropathy with a mean age of disease onset of 13.5 ± 9.6 (1-40) years. Their motor nerve conduction velocities (MNCVs) of the ulnar nerve ranged from 22.1 to 48.7 m/s. Seventy percent of the patients could be classified as intermediate CMT with ulnar MNCVs between 25 and 45 m/s. Six of the 21 patients (28.6%) had additional features of central nervous system (CNS) involvement, including motor developmental delay, spasticity, cerebellar signs, neuropathic pain and scoliosis. CONCLUSION NEFL mutations account for 1.8% (9/508) of the CMT patients in Taiwan. The present study delineates the clinical and genetic characteristics of NEFL-related neuropathy in Taiwan, and highlights that ulnar MNCV above 25 m/s and CNS involvement may serve as diagnostic clues for NEFL-related neuropathy.
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