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Testa L, Dotta S, Vercelli A, Marvaldi L. Communicating pain: emerging axonal signaling in peripheral neuropathic pain. Front Neuroanat 2024; 18:1398400. [PMID: 39045347 PMCID: PMC11265228 DOI: 10.3389/fnana.2024.1398400] [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: 03/09/2024] [Accepted: 05/21/2024] [Indexed: 07/25/2024] Open
Abstract
Peripheral nerve damage often leads to the onset of neuropathic pain (NeuP). This condition afflicts millions of people, significantly burdening healthcare systems and putting strain on families' financial well-being. Here, we will focus on the role of peripheral sensory neurons, specifically the Dorsal Root Ganglia neurons (DRG neurons) in the development of NeuP. After axotomy, DRG neurons activate regenerative signals of axons-soma communication to promote a gene program that activates an axonal branching and elongation processes. The results of a neuronal morphological cytoskeleton change are not always associated with functional recovery. Moreover, any axonal miss-targeting may contribute to NeuP development. In this review, we will explore the epidemiology of NeuP and its molecular causes at the level of the peripheral nervous system and the target organs, with major focus on the neuronal cross-talk between intrinsic and extrinsic factors. Specifically, we will describe how failures in the neuronal regenerative program can exacerbate NeuP.
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Affiliation(s)
- Livia Testa
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano (Torino), Torino, Italy
- Department of Neuroscience “Rita Levi-Montalcini”, Torino, Italy
| | - Sofia Dotta
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano (Torino), Torino, Italy
- Department of Neuroscience “Rita Levi-Montalcini”, Torino, Italy
| | - Alessandro Vercelli
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano (Torino), Torino, Italy
- Department of Neuroscience “Rita Levi-Montalcini”, Torino, Italy
| | - Letizia Marvaldi
- Neuroscience Institute Cavalieri Ottolenghi, Orbassano (Torino), Torino, Italy
- Department of Neuroscience “Rita Levi-Montalcini”, Torino, Italy
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2
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Scherer SS, Svaren J. Peripheral Nervous System (PNS) Myelin Diseases. Cold Spring Harb Perspect Biol 2024; 16:a041376. [PMID: 38253417 PMCID: PMC11065170 DOI: 10.1101/cshperspect.a041376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
This is a review of inherited and acquired causes of human demyelinating neuropathies and a subset of disorders that affect axon-Schwann cell interactions. Nearly all inherited demyelinating neuropathies are caused by mutations in genes that are expressed by myelinating Schwann cells, affecting diverse functions in a cell-autonomous manner. The most common acquired demyelinating neuropathies are Guillain-Barré syndrome and chronic, inflammatory demyelinating polyneuropathy, both of which are immune-mediated. An additional group of inherited and acquired disorders affect axon-Schwann cell interactions in the nodal region. Overall, these disorders affect the formation of myelin and its maintenance, with superimposed axonal loss that is clinically important.
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Affiliation(s)
- Steven S Scherer
- Department of Neurology, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - John Svaren
- Department of Comparative Biosciences, Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin 53705, USA
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3
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Yeh JY, Chao HC, Hong CL, Hung YC, Tzou FY, Hsiao CT, Li JL, Chen WJ, Chou CT, Tsai YS, Liao YC, Lin YC, Lin S, Huang SY, Kennerson M, Lee YC, Chan CC. A missense mutation in human INSC causes peripheral neuropathy. EMBO Mol Med 2024; 16:1091-1114. [PMID: 38589651 PMCID: PMC11099080 DOI: 10.1038/s44321-024-00062-w] [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: 10/03/2023] [Revised: 03/08/2024] [Accepted: 03/15/2024] [Indexed: 04/10/2024] Open
Abstract
PAR3/INSC/LGN form an evolutionarily conserved complex required for asymmetric cell division in the developing brain, but its post-developmental function and disease relevance in the peripheral nervous system (PNS) remains unknown. We mapped a new locus for axonal Charcot-Marie-Tooth disease (CMT2) and identified a missense mutation c.209 T > G (p.Met70Arg) in the INSC gene. Modeling the INSCM70R variant in Drosophila, we showed that it caused proprioceptive defects in adult flies, leading to gait defects resembling those in CMT2 patients. Cellularly, PAR3/INSC/LGN dysfunction caused tubulin aggregation and necrotic neurodegeneration, with microtubule-stabilizing agents rescuing both morphological and functional defects of the INSCM70R mutation in the PNS. Our findings underscore the critical role of the PAR3/INSC/LGN machinery in the adult PNS and highlight a potential therapeutic target for INSC-associated CMT2.
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Affiliation(s)
- Jui-Yu Yeh
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Hua-Chuan Chao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei, Taiwan
- Division of Neurology, Department of Medicine, Taoyuan General Hospital, Ministry of Health and Welfare, Taoyuan, Taiwan
| | - Cheng-Li Hong
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Yu-Chien Hung
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Fei-Yang Tzou
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan
| | - Cheng-Tsung Hsiao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jeng-Lin Li
- Ph.D. Program in Translational Medicine, National Taiwan University and Academia Sinica, Taipei, Taiwan
- Department of Neurology, National Taiwan University Hospital Jinshan Branch, New Taipei City, Taiwan
| | - Wen-Jie Chen
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
- Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Cheng Kung University and Academia Sinica, Tapiei, Taiwan
| | - Cheng-Ta Chou
- Department of Neurology, Neurological Institute, Taichung Veterans General Hospital, Taichung, Taiwan
| | - Yu-Shuen Tsai
- Cancer and Immunology Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Chu Liao
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan
- Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan
| | - Yu-Chun Lin
- Institute of Molecular Medicine, National Tsing Hua University, HsinChu, Taiwan
- Department of Medical Science, National Tsing Hua University, HsinChu, Taiwan
| | - Suewei Lin
- Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan
| | - Shu-Yi Huang
- Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan
| | - Marina Kennerson
- Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney Local Health District, Concord, NSW, Australia
- School of Medical Sciences, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia
- Molecular Medicine Laboratory, Concord Hospital, Concord, NSW, Australia
| | - Yi-Chung Lee
- Department of Neurology, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan.
- Department of Neurology, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan.
- Brain Research Center, National Yang Ming Chiao Tung University School of Medicine, Taipei, Taiwan.
| | - Chih-Chiang Chan
- Graduate Institute of Physiology, National Taiwan University, Taipei, Taiwan.
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4
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Daboussi L, Costaguta G, Gullo M, Jasinski N, Pessino V, O'Leary B, Lettieri K, Driscoll S, Pfaff SL. Mitf is a Schwann cell sensor of axonal integrity that drives nerve repair. Cell Rep 2023; 42:113282. [PMID: 38007688 PMCID: PMC11034927 DOI: 10.1016/j.celrep.2023.113282] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 08/04/2023] [Accepted: 09/28/2023] [Indexed: 11/27/2023] Open
Abstract
Schwann cells respond to acute axon damage by transiently transdifferentiating into specialized repair cells that restore sensorimotor function. However, the molecular systems controlling repair cell formation and function are not well defined, and consequently, it is unclear whether this form of cellular plasticity has a role in peripheral neuropathies. Here, we identify Mitf as a transcriptional sensor of axon damage under the control of Nrg-ErbB-PI3K-PI5K-mTorc2 signaling. Mitf regulates a core transcriptional program for generating functional repair Schwann cells following injury and during peripheral neuropathies caused by CMT4J and CMT4D. In the absence of Mitf, core genes for epithelial-to-mesenchymal transition, metabolism, and dedifferentiation are misexpressed, and nerve repair is disrupted. Our findings demonstrate that Schwann cells monitor axonal health using a phosphoinositide signaling system that controls Mitf nuclear localization, which is critical for activating cellular plasticity and counteracting neural disease.
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Affiliation(s)
- Lydia Daboussi
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA; Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Giancarlo Costaguta
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA; Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Miriam Gullo
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Nicole Jasinski
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Veronica Pessino
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Brendan O'Leary
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Karen Lettieri
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Shawn Driscoll
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA
| | - Samuel L Pfaff
- Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines, La Jolla, CA 92037, USA.
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Kuznetsov IA, Kuznetsov AV. Dynein Dysfunction Prevents Maintenance of High Concentrations of Slow Axonal Transport Cargos at the Axon Terminal: A Computational Study. J Biomech Eng 2023; 145:071001. [PMID: 36795013 PMCID: PMC10158974 DOI: 10.1115/1.4056915] [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: 07/03/2022] [Revised: 02/06/2023] [Accepted: 02/08/2023] [Indexed: 02/17/2023]
Abstract
Here, we report computational studies of bidirectional transport in an axon, specifically focusing on predictions when the retrograde motor becomes dysfunctional. We are motivated by reports that mutations in dynein-encoding genes can cause diseases associated with peripheral motor and sensory neurons, such as type 2O Charcot-Marie-Tooth disease. We use two different models to simulate bidirectional transport in an axon: an anterograde-retrograde model, which neglects passive transport by diffusion in the cytosol, and a full slow transport model, which includes passive transport by diffusion in the cytosol. As dynein is a retrograde motor, its dysfunction should not directly influence anterograde transport. However, our modeling results unexpectedly predict that slow axonal transport fails to transport cargos against their concentration gradient without dynein. The reason is the lack of a physical mechanism for the reverse information flow from the axon terminal, which is required so that the cargo concentration at the terminal could influence the cargo concentration distribution in the axon. Mathematically speaking, to achieve a prescribed concentration at the terminal, equations governing cargo transport must allow for the imposition of a boundary condition postulating the cargo concentration at the terminal. Perturbation analysis for the case when the retrograde motor velocity becomes close to zero predicts uniform cargo distributions along the axon. The obtained results explain why slow axonal transport must be bidirectional to allow for the maintenance of concentration gradients along the axon length. Our result is limited to small cargo diffusivity, which is a reasonable assumption for many slow axonal transport cargos (such as cytosolic and cytoskeletal proteins, neurofilaments, actin, and microtubules) which are transported as large multiprotein complexes or polymers.
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Affiliation(s)
- Ivan A. Kuznetsov
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Andrey V. Kuznetsov
- Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695-7910
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Hirsch Y, Chung WK, Novoselov S, Weimer LH, Rossor A, LeDuc CA, McPartland AJ, Cabrera E, Ekstein J, Scher S, Nelson RF, Schiavo G, Henderson LB, Booth KTA. Biallelic Loss-of-Function Variants in BICD1 Are Associated with Peripheral Neuropathy and Hearing Loss. Int J Mol Sci 2023; 24:8897. [PMID: 37240244 PMCID: PMC10219021 DOI: 10.3390/ijms24108897] [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: 03/27/2023] [Revised: 05/16/2023] [Accepted: 05/16/2023] [Indexed: 05/28/2023] Open
Abstract
Hearing loss and peripheral neuropathy are two clinical entities that are genetically and phenotypically heterogeneous and sometimes co-occurring. Using exome sequencing and targeted segregation analysis, we investigated the genetic etiology of peripheral neuropathy and hearing loss in a large Ashkenazi Jewish family. Moreover, we assessed the production of the candidate protein via western blotting of lysates from fibroblasts from an affected individual and an unaffected control. Pathogenic variants in known disease genes associated with hearing loss and peripheral neuropathy were excluded. A homozygous frameshift variant in the BICD1 gene, c.1683dup (p.(Arg562Thrfs*18)), was identified in the proband and segregated with hearing loss and peripheral neuropathy in the family. The BIDC1 RNA analysis from patient fibroblasts showed a modest reduction in gene transcripts compared to the controls. In contrast, protein could not be detected in fibroblasts from a homozygous c.1683dup individual, whereas BICD1 was detected in an unaffected individual. Our findings indicate that bi-allelic loss-of-function variants in BICD1 are associated with hearing loss and peripheral neuropathy. Definitive evidence that bi-allelic loss-of-function variants in BICD1 cause peripheral neuropathy and hearing loss will require the identification of other families and individuals with similar variants with the same phenotype.
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Affiliation(s)
- Yoel Hirsch
- Dor Yeshorim, Committee for Prevention Jewish Genetic Diseases, Brooklyn, NY 11211, USA
| | - Wendy K. Chung
- Departments of Pediatrics and Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Sergey Novoselov
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Louis H. Weimer
- Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Alexander Rossor
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
| | - Charles A. LeDuc
- Departments of Pediatrics and Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Amanda J. McPartland
- Departments of Pediatrics and Medicine, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Ernesto Cabrera
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Josef Ekstein
- Dor Yeshorim, Committee for Prevention Jewish Genetic Diseases, Brooklyn, NY 11211, USA
| | - Sholem Scher
- Dor Yeshorim, Committee for Prevention Jewish Genetic Diseases, Brooklyn, NY 11211, USA
| | - Rick F. Nelson
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
- UK Dementia Research Institute at UCL, London WC1E 6BT, UK
| | | | - Kevin T. A. Booth
- Department of Otolaryngology-Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA
- Medical and Molecular Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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7
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El-Bazzal L, Ghata A, Estève C, Gadacha J, Quintana P, Castro C, Roeckel-Trévisiol N, Lembo F, Lenfant N, Mégarbané A, Borg JP, Lévy N, Bartoli M, Poitelon Y, Roubertoux PL, Delague V, Bernard-Marissal N. Imbalance of NRG1-ERBB2/3 signalling underlies altered myelination in Charcot-Marie-Tooth disease 4H. Brain 2023; 146:1844-1858. [PMID: 36314052 PMCID: PMC10151191 DOI: 10.1093/brain/awac402] [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: 03/25/2022] [Revised: 08/30/2022] [Accepted: 10/02/2022] [Indexed: 11/12/2022] Open
Abstract
Charcot-Marie-Tooth (CMT) disease is one of the most common inherited neurological disorders, affecting either axons from the motor and/or sensory neurons or Schwann cells of the peripheral nervous system (PNS) and caused by more than 100 genes. We previously identified mutations in FGD4 as responsible for CMT4H, an autosomal recessive demyelinating form of CMT disease. FGD4 encodes FRABIN, a GDP/GTP nucleotide exchange factor, particularly for the small GTPase Cdc42. Remarkably, nerves from patients with CMT4H display excessive redundant myelin figures called outfoldings that arise from focal hypermyelination, suggesting that FRABIN could play a role in the control of PNS myelination. To gain insights into the role of FGD4/FRABIN in Schwann cell myelination, we generated a knockout mouse model (Fgd4SC-/-), with conditional ablation of Fgd4 in Schwann cells. We show that the specific deletion of FRABIN in Schwann cells leads to aberrant myelination in vitro, in dorsal root ganglia neuron/Schwann cell co-cultures, as well as in vivo, in distal sciatic nerves from Fgd4SC-/- mice. We observed that those myelination defects are related to an upregulation of some interactors of the NRG1 type III/ERBB2/3 signalling pathway, which is known to ensure a proper level of myelination in the PNS. Based on a yeast two-hybrid screen, we identified SNX3 as a new partner of FRABIN, which is involved in the regulation of endocytic trafficking. Interestingly, we showed that the loss of FRABIN impairs endocytic trafficking, which may contribute to the defective NRG1 type III/ERBB2/3 signalling and myelination. Using RNA-Seq, in vitro, we identified new potential effectors of the deregulated pathways, such as ERBIN, RAB11FIP2 and MAF, thereby providing cues to understand how FRABIN contributes to proper ERBB2 trafficking or even myelin membrane addition through cholesterol synthesis. Finally, we showed that the re-establishment of proper levels of the NRG1 type III/ERBB2/3 pathway using niacin treatment reduces myelin outfoldings in nerves of CMT4H mice. Overall, our work reveals a new role of FRABIN in the regulation of NRG1 type III/ERBB2/3 NRG1signalling and myelination and opens future therapeutic strategies based on the modulation of the NRG1 type III/ERBB2/3 pathway to reduce CMT4H pathology and more generally other demyelinating types of CMT disease.
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Affiliation(s)
- Lara El-Bazzal
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | - Adeline Ghata
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | | | - Jihane Gadacha
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | | | | | | | - Frédérique Lembo
- Aix Marseille Univ, INSERM, CNRS, CRCM, Institut Paoli-Calmettes, Marseille, France
| | | | - André Mégarbané
- Department of Human Genetics, Gilbert and Rose-Marie Chagoury School of Medicine, Lebanese American University, Beirut, Lebanon
| | - Jean-Paul Borg
- Aix Marseille Univ, INSERM, CNRS, CRCM, Institut Paoli-Calmettes, Marseille, France
| | - Nicolas Lévy
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | - Marc Bartoli
- Aix Marseille Univ, INSERM, MMG, U 1251, Marseille, France
| | - Yannick Poitelon
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, USA
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8
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Piol D, Robberechts T, Da Cruz S. Lost in local translation: TDP-43 and FUS in axonal/neuromuscular junction maintenance and dysregulation in amyotrophic lateral sclerosis. Neuron 2023; 111:1355-1380. [PMID: 36963381 DOI: 10.1016/j.neuron.2023.02.028] [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: 10/19/2022] [Revised: 12/21/2022] [Accepted: 02/16/2023] [Indexed: 03/26/2023]
Abstract
Key early features of amyotrophic lateral sclerosis (ALS) are denervation of neuromuscular junctions and axonal degeneration. Motor neuron homeostasis relies on local translation through controlled regulation of axonal mRNA localization, transport, and stability. Yet the composition of the local transcriptome, translatome (mRNAs locally translated), and proteome during health and disease remains largely unexplored. This review covers recent discoveries on axonal translation as a critical mechanism for neuronal maintenance/survival. We focus on two RNA binding proteins, transactive response DNA binding protein-43 (TDP-43) and fused in sarcoma (FUS), whose mutations cause ALS and frontotemporal dementia (FTD). Emerging evidence points to their essential role in the maintenance of axons and synapses, including mRNA localization, transport, and local translation, and whose dysfunction may contribute to ALS. Finally, we describe recent advances in omics-based approaches mapping compartment-specific local RNA and protein compositions, which will be invaluable to elucidate fundamental local processes and identify key targets for therapy development.
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Affiliation(s)
- Diana Piol
- VIB-KU Leuven Center for Brain and Disease Research, Department of Neurosciences, KU Leuven, Leuven Brain Institute, Leuven, Belgium
| | - Tessa Robberechts
- VIB-KU Leuven Center for Brain and Disease Research, Department of Neurosciences, KU Leuven, Leuven Brain Institute, Leuven, Belgium
| | - Sandrine Da Cruz
- VIB-KU Leuven Center for Brain and Disease Research, Department of Neurosciences, KU Leuven, Leuven Brain Institute, Leuven, Belgium.
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9
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Sainio MT, Rasila T, Molchanova SM, Järvilehto J, Torregrosa-Muñumer R, Harjuhaahto S, Pennonen J, Huber N, Herukka SK, Haapasalo A, Zetterberg H, Taira T, Palmio J, Ylikallio E, Tyynismaa H. Neurofilament Light Regulates Axon Caliber, Synaptic Activity, and Organelle Trafficking in Cultured Human Motor Neurons. Front Cell Dev Biol 2022; 9:820105. [PMID: 35237613 PMCID: PMC8883324 DOI: 10.3389/fcell.2021.820105] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 12/28/2021] [Indexed: 11/27/2022] Open
Abstract
Neurofilament light (NFL) is one of the proteins forming multimeric neuron-specific intermediate filaments, neurofilaments, which fill the axonal cytoplasm, establish caliber growth, and provide structural support. Dominant missense mutations and recessive nonsense mutations in the neurofilament light gene (NEFL) are among the causes of Charcot-Marie-Tooth (CMT) neuropathy, which affects the peripheral nerves with the longest axons. We previously demonstrated that a neuropathy-causing homozygous nonsense mutation in NEFL led to the absence of NFL in patient-specific neurons. To understand the disease-causing mechanisms, we investigate here the functional effects of NFL loss in human motor neurons differentiated from induced pluripotent stem cells (iPSC). We used genome editing to generate NEFL knockouts and compared them to patient-specific nonsense mutants and isogenic controls. iPSC lacking NFL differentiated efficiently into motor neurons with normal axon growth and regrowth after mechanical axotomy and contained neurofilaments. Electrophysiological analysis revealed that motor neurons without NFL fired spontaneous and evoked action potentials with similar characteristics as controls. However, we found that, in the absence of NFL, human motor neurons 1) had reduced axonal caliber, 2) the amplitude of miniature excitatory postsynaptic currents (mEPSC) was decreased, 3) neurofilament heavy (NFH) levels were reduced and no compensatory increases in other filament subunits were observed, and 4) the movement of mitochondria and to a lesser extent lysosomes was increased. Our findings elaborate the functional roles of NFL in human motor neurons. NFL is not only a structural protein forming neurofilaments and filling the axonal cytoplasm, but our study supports the role of NFL in the regulation of synaptic transmission and organelle trafficking. To rescue the NFL deficiency in the patient-specific nonsense mutant motor neurons, we used three drugs, amlexanox, ataluren (PTC-124), and gentamicin to induce translational read-through or inhibit nonsense-mediated decay. However, the drugs failed to increase the amount of NFL protein to detectable levels and were toxic to iPSC-derived motor neurons.
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Affiliation(s)
- Markus T. Sainio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tiina Rasila
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Svetlana M. Molchanova
- Molecular and Integrative Biosciences Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Julius Järvilehto
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Rubén Torregrosa-Muñumer
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Sandra Harjuhaahto
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jana Pennonen
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Nadine Huber
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Sanna-Kaisa Herukka
- Department of Neurology, Kuopio University Hospital, Kuopio, Finland
- Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Annakaisa Haapasalo
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Henrik Zetterberg
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden
- Department of Neurodegenerative Disease, UCL Institute of Neurology, London, United Kingdom
- UK Dementia Research Institute at UCL, London, United Kingdom
- Hong Kong Center for Neurodegenerative Diseases, Hong Kong, Hong Kong SAR, China
| | - Tomi Taira
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, Department of Veterinary Biosciences for Electrophysiology, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Johanna Palmio
- Neuromuscular Research Center, Tampere University Hospital and Tampere University, Tampere, Finland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
- Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
- Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
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