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Ding EA, Kumar S. Neurofilament Biophysics: From Structure to Biomechanics. Mol Biol Cell 2024; 35:re1. [PMID: 38598299 PMCID: PMC11151108 DOI: 10.1091/mbc.e23-11-0438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/25/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024] Open
Abstract
Neurofilaments (NFs) are multisubunit, neuron-specific intermediate filaments consisting of a 10-nm diameter filament "core" surrounded by a layer of long intrinsically disordered protein (IDP) "tails." NFs are thought to regulate axonal caliber during development and then stabilize the mature axon, with NF subunit misregulation, mutation, and aggregation featuring prominently in multiple neurological diseases. The field's understanding of NF structure, mechanics, and function has been deeply informed by a rich variety of biochemical, cell biological, and mouse genetic studies spanning more than four decades. These studies have contributed much to our collective understanding of NF function in axonal physiology and disease. In recent years, however, there has been a resurgence of interest in NF subunit proteins in two new contexts: as potential blood- and cerebrospinal fluid-based biomarkers of neuronal damage, and as model IDPs with intriguing properties. Here, we review established principles and more recent discoveries in NF structure and function. Where possible, we place these findings in the context of biophysics of NF assembly, interaction, and contributions to axonal mechanics.
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Affiliation(s)
- Erika A. Ding
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Sanjay Kumar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158
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2
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Bin JM, Suminaite D, Benito-Kwiecinski SK, Kegel L, Rubio-Brotons M, Early JJ, Soong D, Livesey MR, Poole RJ, Lyons DA. Importin 13-dependent axon diameter growth regulates conduction speeds along myelinated CNS axons. Nat Commun 2024; 15:1790. [PMID: 38413580 PMCID: PMC10899189 DOI: 10.1038/s41467-024-45908-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Accepted: 02/06/2024] [Indexed: 02/29/2024] Open
Abstract
Axon diameter influences the conduction properties of myelinated axons, both directly, and indirectly through effects on myelin. However, we have limited understanding of mechanisms controlling axon diameter growth in the central nervous system, preventing systematic dissection of how manipulating diameter affects myelination and conduction along individual axons. Here we establish zebrafish to study axon diameter. We find that importin 13b is required for axon diameter growth, but does not affect cell body size or axon length. Using neuron-specific ipo13b mutants, we assess how reduced axon diameter affects myelination and conduction, and find no changes to myelin thickness, precision of action potential propagation, or ability to sustain high frequency firing. However, increases in conduction speed that occur along single myelinated axons with development are tightly linked to their growth in diameter. This suggests that axon diameter growth is a major driver of increases in conduction speeds along myelinated axons over time.
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Affiliation(s)
- Jenea M Bin
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK.
| | - Daumante Suminaite
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | | | - Linde Kegel
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Maria Rubio-Brotons
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Jason J Early
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Daniel Soong
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | - Matthew R Livesey
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield, S10 2HQ, UK
- Neuroscience Institute, University of Sheffield, Sheffield, S10 2TN, UK
| | - Richard J Poole
- Department of Cell and Developmental Biology, University College London, London, WC1E 6BT, UK
| | - David A Lyons
- Centre for Discovery Brain Sciences, University of Edinburgh, Edinburgh, EH16 4SB, UK.
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3
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López-Erauskin J, Bravo-Hernandez M, Presa M, Baughn MW, Melamed Z, Beccari MS, Agra de Almeida Quadros AR, Arnold-Garcia O, Zuberi A, Ling K, Platoshyn O, Niño-Jara E, Ndayambaje IS, McAlonis-Downes M, Cabrera L, Artates JW, Ryan J, Hermann A, Ravits J, Bennett CF, Jafar-Nejad P, Rigo F, Marsala M, Lutz CM, Cleveland DW, Lagier-Tourenne C. Stathmin-2 loss leads to neurofilament-dependent axonal collapse driving motor and sensory denervation. Nat Neurosci 2024; 27:34-47. [PMID: 37996528 PMCID: PMC10842032 DOI: 10.1038/s41593-023-01496-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2022] [Accepted: 10/16/2023] [Indexed: 11/25/2023]
Abstract
The mRNA transcript of the human STMN2 gene, encoding for stathmin-2 protein (also called SCG10), is profoundly impacted by TAR DNA-binding protein 43 (TDP-43) loss of function. The latter is a hallmark of several neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Using a combination of approaches, including transient antisense oligonucleotide-mediated suppression, sustained shRNA-induced depletion in aging mice, and germline deletion, we show that stathmin-2 has an important role in the establishment and maintenance of neurofilament-dependent axoplasmic organization that is critical for preserving the caliber and conduction velocity of myelinated large-diameter axons. Persistent stathmin-2 loss in adult mice results in pathologies found in ALS, including reduced interneurofilament spacing, axonal caliber collapse that drives tearing within outer myelin layers, diminished conduction velocity, progressive motor and sensory deficits, and muscle denervation. These findings reinforce restoration of stathmin-2 as an attractive therapeutic approach for ALS and other TDP-43-dependent neurodegenerative diseases.
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Affiliation(s)
- Jone López-Erauskin
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Mariana Bravo-Hernandez
- Department of Anesthesiology and Stem Cell Program and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA, USA
- Ionis Pharmaceuticals Inc., Carlsbad, CA, USA
| | | | - Michael W Baughn
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Ze'ev Melamed
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
- Department of Medical Neurobiology, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Melinda S Beccari
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Ana Rita Agra de Almeida Quadros
- Department of Neurology, The Sean M. Healey and AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Olatz Arnold-Garcia
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
- Department of Neurosciences, Biodonostia Health Research Institute, San Sebastián, Spain
- CIBERNED, ISCIII (CIBER, Carlos III Institute, Spanish Ministry of Sciences and Innovation), Madrid, Spain
| | | | - Karen Ling
- Ionis Pharmaceuticals Inc., Carlsbad, CA, USA
| | - Oleksandr Platoshyn
- Department of Anesthesiology and Stem Cell Program and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Elkin Niño-Jara
- Department of Anesthesiology and Stem Cell Program and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA, USA
| | - I Sandra Ndayambaje
- Department of Neurology, The Sean M. Healey and AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Melissa McAlonis-Downes
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Larissa Cabrera
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | - Jonathan W Artates
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA
| | | | - Anita Hermann
- Department of Neurosciences, School of Medicine, University of California at San Diego, La Jolla, CA, USA
| | - John Ravits
- Department of Neurosciences, School of Medicine, University of California at San Diego, La Jolla, CA, USA
| | | | | | - Frank Rigo
- Ionis Pharmaceuticals Inc., Carlsbad, CA, USA
| | - Martin Marsala
- Department of Anesthesiology and Stem Cell Program and Institute for Genomic Medicine, University of California at San Diego, La Jolla, CA, USA
| | | | - Don W Cleveland
- Ludwig Institute and Department of Cellular and Molecular Medicine, University of California at San Diego, La Jolla, CA, USA.
| | - Clotilde Lagier-Tourenne
- Department of Neurology, The Sean M. Healey and AMG Center for ALS, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA.
- Broad Institute of Harvard and MIT, Cambridge, MA, USA.
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4
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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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5
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Krieg JL, Leonard AV, Turner RJ, Corrigan F. Identifying the Phenotypes of Diffuse Axonal Injury Following Traumatic Brain Injury. Brain Sci 2023; 13:1607. [PMID: 38002566 PMCID: PMC10670443 DOI: 10.3390/brainsci13111607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/15/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023] Open
Abstract
Diffuse axonal injury (DAI) is a significant feature of traumatic brain injury (TBI) across all injury severities and is driven by the primary mechanical insult and secondary biochemical injury phases. Axons comprise an outer cell membrane, the axolemma which is anchored to the cytoskeletal network with spectrin tetramers and actin rings. Neurofilaments act as space-filling structural polymers that surround the central core of microtubules, which facilitate axonal transport. TBI has differential effects on these cytoskeletal components, with axons in the same white matter tract showing a range of different cytoskeletal and axolemma alterations with different patterns of temporal evolution. These require different antibodies for detection in post-mortem tissue. Here, a comprehensive discussion of the evolution of axonal injury within different cytoskeletal elements is provided, alongside the most appropriate methods of detection and their temporal profiles. Accumulation of amyloid precursor protein (APP) as a result of disruption of axonal transport due to microtubule failure remains the most sensitive marker of axonal injury, both acutely and chronically. However, a subset of injured axons demonstrate different pathology, which cannot be detected via APP immunoreactivity, including degradation of spectrin and alterations in neurofilaments. Furthermore, recent work has highlighted the node of Ranvier and the axon initial segment as particularly vulnerable sites to axonal injury, with loss of sodium channels persisting beyond the acute phase post-injury in axons without APP pathology. Given the heterogenous response of axons to TBI, further characterization is required in the chronic phase to understand how axonal injury evolves temporally, which may help inform pharmacological interventions.
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Affiliation(s)
- Justin L Krieg
- Translational Neuropathology Laboratory, School of Biomedicine, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide 5000, Australia
| | - Anna V Leonard
- Translational Neuropathology Laboratory, School of Biomedicine, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide 5000, Australia
| | - Renée J Turner
- Translational Neuropathology Laboratory, School of Biomedicine, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide 5000, Australia
| | - Frances Corrigan
- Translational Neuropathology Laboratory, School of Biomedicine, Faculty of Health and Medical Sciences, The University of Adelaide, Adelaide 5000, Australia
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6
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Zhulina EB, Borisov OV. Cylindrical brushes with ionized side chains: Scaling theory revisited. SOFT MATTER 2023; 19:8440-8452. [PMID: 37881868 DOI: 10.1039/d3sm00727h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2023]
Abstract
We revisit the classic scaling model of a cylindrical polyelectrolyte (PE) brush focusing on molecular brushes with stiff backbones and dispersions of polymer-decorated nanorods. Based on the blob representation we demonstrate that similarly to the case of planar PE brushes, separation of intra- and intermolecular repulsions between charges leads to novel scaling regimes for cylindrical PE brushes in salt-added solution and a sharper decrease in its thickness versus salt concentration dependence. These theoretical predictions may inspire further comprehensive experimental research and computer simulations of synthetic and biopolyelectrolyte cylindrical brushes.
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Affiliation(s)
- Ekaterina B Zhulina
- Institute of Macromolecular Compounds of the Russian Academy of Sciences, St. Petersburg, Russia.
| | - Oleg V Borisov
- Institute of Macromolecular Compounds of the Russian Academy of Sciences, St. Petersburg, Russia.
- Institut des Sciences Analytiques et de Physico-Chimie pour l'Environnement et les Matériaux, UMR 5254 CNRS UPPA, Pau, France
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7
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Uchida A, Peng J, Brown A. Regulation of neurofilament length and transport by a dynamic cycle of phospho-dependent polymer severing and annealing. Mol Biol Cell 2023; 34:ar68. [PMID: 36989035 PMCID: PMC10295484 DOI: 10.1091/mbc.e23-01-0024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 03/30/2023] Open
Abstract
Neurofilaments are cargoes of axonal transport which are unique among known intracellular cargoes in that they are long, flexible protein polymers. These polymers are transported into axons, where they accumulate in large numbers to drive the expansion of axon caliber, which is an important determinant of axonal conduction velocity. We reported previously that neurofilaments can be lengthened by joining ends, called end-to-end annealing, and that they can be shortened by severing. Here, we show that neurofilament annealing and severing are robust and quantifiable phenomena in cultured neurons that act antagonistically to regulate neurofilament length. We show that this in turn regulates neurofilament transport and that severing is regulated by N-terminal phosphorylation of the neurofilament subunit proteins. We propose that focal destabilization of intermediate filaments by site-directed phosphorylation may be a general enzymatic mechanism for severing these cytoskeletal polymers, providing a mechanism to regulate the transport and accumulation of neurofilaments in axons.
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Affiliation(s)
- Atsuko Uchida
- Department of Neuroscience, Ohio State University, Columbus, OH 43210
| | - Juan Peng
- Center for Biostatistics and Department of Biomedical Informatics, Ohio State University, Columbus, OH 43210
| | - Anthony Brown
- Department of Neuroscience, Ohio State University, Columbus, OH 43210
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8
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Paus T. Tracking Development of Connectivity in the Human Brain: Axons and Dendrites. Biol Psychiatry 2023; 93:455-463. [PMID: 36344316 DOI: 10.1016/j.biopsych.2022.08.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Revised: 07/15/2022] [Accepted: 08/02/2022] [Indexed: 02/04/2023]
Abstract
The neuron doctrine laid the foundation for our current thinking about the structural and functional organization of the human brain. With the basic units of the nervous system-neurons-being physically separate, their connectivity relies on the conduction of action potentials in axons and their transmission across the synaptic cleft to the dendrites of other neurons. This study reviews available ex vivo data about the cellular composition of the human cerebral cortex, focusing on axons and dendrites, to conceptualize biological sources of signals detected in vivo with magnetic resonance imaging. To bridge the gap between ex vivo and in vivo observations, I then explain the basic principles of virtual histology, an approach that integrates spatially cell- or process-specific transcriptomic data with magnetic resonance signals to facilitate their neurobiological interpretation. Finally, I provide an overview of the initial insights gained in this manner in studies of brain development and maturation, in both health and disease.
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Affiliation(s)
- Tomáš Paus
- Departments of Psychiatry and Neuroscience, Faculty of Medicine and Centre Hospitalier Universitaire Sainte-Justine, University of Montréal, Montreal, Quebec, Canada.
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9
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Zhang Q, Fan W, Sun J, Zhang J, Yin Y. Review of Neurofilaments as Biomarkers in Sepsis-Associated Encephalopathy. J Inflamm Res 2023; 16:161-168. [PMID: 36660377 PMCID: PMC9843472 DOI: 10.2147/jir.s391325] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 12/24/2022] [Indexed: 01/12/2023] Open
Abstract
Sepsis is a common and fatal disease, especially in critically ill patients. Sepsis-associated encephalopathy (SAE) is a diffuse brain dysfunction with acute altered consciousness, permanent cognitive impairment, and even coma, accompanied by sepsis, without direct central nervous system infection. When managing SAE, early identification and quantification of axonal damage facilitate faster and more accurate diagnosis and prognosis. Although no specific markers for SAE have been identified, several biomarkers have been proposed. Neurofilament light chain (NFL) is a highly expressed cytoskeletal component of neurofilament (NF) proteins that can be found in blood and cerebrospinal fluid (CSF) after exposure to axonal injury. NFs can be used as diagnostic and prognostic biomarkers for sepsis-related brain injury. Phosphorylation of NFs contributes to the maturation and stabilization of cytoskeletal structures, especially axons, and facilitates axonal transport, including mitochondrial transport and energy transport. The stability of NF proteins can be assessed by monitoring the expression of NF genes. Furthermore, phosphorylation levels of NFs can be monitored to determine mitochondrial axonal transport associated with cellular energy metabolism at distal axons to assess progression during SAE treatment. This paper provides new insights into the biological characteristics, detection techniques, and scientific achievements of NFs, and discusses the underlying mechanisms and future research directions of NFs in SAE.
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Affiliation(s)
- Qiulei Zhang
- Department of Emergency and Critical Care, The Second Hospital of Jilin University, Changchun, 130021, People’s Republic of China
| | - Weixuan Fan
- Department of Emergency and Critical Care, The Second Hospital of Jilin University, Changchun, 130021, People’s Republic of China
| | - Jian Sun
- Department of Emergency and Critical Care, The Second Hospital of Jilin University, Changchun, 130021, People’s Republic of China
| | - Jingxiao Zhang
- Department of Emergency and Critical Care, The Second Hospital of Jilin University, Changchun, 130021, People’s Republic of China,Correspondence: Jingxiao Zhang; Yongjie Yin, Tel +86-13756314698; +86-13596103459, Email ;
| | - Yongjie Yin
- Department of Emergency and Critical Care, The Second Hospital of Jilin University, Changchun, 130021, People’s Republic of China
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10
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Schwann cell functions in peripheral nerve development and repair. Neurobiol Dis 2023; 176:105952. [PMID: 36493976 DOI: 10.1016/j.nbd.2022.105952] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/23/2022] [Accepted: 12/05/2022] [Indexed: 12/12/2022] Open
Abstract
The glial cell of the peripheral nervous system (PNS), the Schwann cell (SC), counts among the most multifaceted cells of the body. During development, SCs secure neuronal survival and participate in axonal path finding. Simultaneously, they orchestrate the architectural set up of the developing nerves, including the blood vessels and the endo-, peri- and epineurial layers. Perinatally, in rodents, SCs radially sort and subsequently myelinate individual axons larger than 1 μm in diameter, while small calibre axons become organised in non-myelinating Remak bundles. SCs have a vital role in maintaining axonal health throughout life and several specialized SC types perform essential functions at specific locations, such as terminal SC at the neuromuscular junction (NMJ) or SC within cutaneous sensory end organs. In addition, neural crest derived satellite glia maintain a tight communication with the soma of sensory, sympathetic, and parasympathetic neurons and neural crest derivatives are furthermore an indispensable part of the enteric nervous system. The remarkable plasticity of SCs becomes evident in the context of a nerve injury, where SC transdifferentiate into intriguing repair cells, which orchestrate a regenerative response that promotes nerve repair. Indeed, the multiple adaptations of SCs are captivating, but remain often ill-resolved on the molecular level. Here, we summarize and discuss the knowns and unknowns of the vast array of functions that this single cell type can cover in peripheral nervous system development, maintenance, and repair.
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11
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Manto KM, Govindappa PK, Martinazzi B, Han A, Hegarty JP, Koroneos Z, Talukder MAH, Elfar JC. Erythropoietin-PLGA-PEG as a local treatment to promote functional recovery and neurovascular regeneration after peripheral nerve injury. J Nanobiotechnology 2022; 20:461. [PMID: 36307805 PMCID: PMC9617443 DOI: 10.1186/s12951-022-01666-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/07/2022] [Indexed: 12/03/2022] Open
Abstract
Background Traumatic peripheral nerve injury (TPNI) is a major medical problem with no universally accepted pharmacologic treatment. We hypothesized that encapsulation of pro-angiogenic erythropoietin (EPO) in amphiphilic PLGA-PEG block copolymers could serve as a local controlled-release drug delivery system to enhance neurovascular regeneration after nerve injury. Methods In this study, we synthesized an EPO-PLGA-PEG block copolymer formulation. We characterized its physiochemical and release properties and examined its effects on functional recovery, neural regeneration, and blood vessel formation after sciatic nerve crush injury in mice. Results EPO-PLGA-PEG underwent solution-to-gel transition within the physiologically relevant temperature window and released stable EPO for up to 18 days. EPO-PLGA-PEG significantly enhanced sciatic function index (SFI), grip strength, and withdrawal reflex post-sciatic nerve crush injury. Furthermore, EPO-PLGA-PEG significantly increased blood vessel density, number of junctions, and myelinated nerve fibers after injury. Conclusion This study provides promising preclinical evidence for using EPO-PLGA-PEG as a local controlled-release treatment to enhance functional outcomes and neurovascular regeneration in TPNI. Supplementary Information The online version contains supplementary material available at 10.1186/s12951-022-01666-5.
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Affiliation(s)
- Kristen M Manto
- Department of Orthopaedics and Rehabilitation, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Prem Kumar Govindappa
- Department of Orthopaedics and Rehabilitation, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA.,Department of Orthopaedics and Sports Medicine, University of Arizona College of Medicine, Tucson, AZ, 85724, USA
| | - Brandon Martinazzi
- Department of Orthopaedics and Rehabilitation, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Aijie Han
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, PA, 16802, USA
| | - John P Hegarty
- Department of Orthopaedics and Rehabilitation, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - Zachary Koroneos
- Department of Orthopaedics and Rehabilitation, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - M A Hassan Talukder
- Department of Orthopaedics and Rehabilitation, The Pennsylvania State University College of Medicine, Hershey, PA, 17033, USA
| | - John C Elfar
- Department of Orthopaedics and Sports Medicine, University of Arizona College of Medicine, Tucson, AZ, 85724, USA.
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12
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Li X, Li M, Wang M, Wu F, Liu H, Sun Q, Zhang Y, Liu C, Jin C, Yang J. Mapping white matter maturational processes and degrees on neonates by diffusion kurtosis imaging with multiparametric analysis. Hum Brain Mapp 2022; 43:799-815. [PMID: 34708903 PMCID: PMC8720196 DOI: 10.1002/hbm.25689] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/03/2021] [Accepted: 10/07/2021] [Indexed: 11/10/2022] Open
Abstract
White matter maturation has been characterized by diffusion tensor (DT) metrics. However, maturational processes and degrees are not fully investigated due to limitations of univariate approaches and limited specificity/sensitivity. Diffusion kurtosis imaging (DKI) provides kurtosis tensor (KT) and white matter tract integrity (WMTI) metrics, besides DT metrics. Therefore, we tried to investigate performances of DKI with the multiparametric analysis in characterizing white matter maturation. Developmental changes in metrics were investigated by using tract-based spatial statistics and the region of interest analysis on 50 neonates with postmenstrual age (PMA) from 37.43 to 43.57 weeks. Changes in metrics were combined into various patterns to reveal different maturational processes. Mahalanobis distance based on DT metrics (DM,DT ) and that combing DT and KT metrics (DM,DT-KT ) were computed, separately. Performances of DM,DT-KT and DM,DT were compared in revealing correlations with PMA and the neurobehavioral score. Compared with DT metrics, WMTI metrics demonstrated additional changing patterns. Furthermore, variations of DM,DT-KT across regions were in agreement with the maturational sequence. Additionally, DM,DT-KT demonstrated stronger negative correlations with PMA and the neurobehavioral score in more regions than DM,DT . Results suggest that DKI with the multiparametric analysis benefits the understanding of white matter maturational processes and degrees on neonates.
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Affiliation(s)
- Xianjun Li
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Mengxuan Li
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Miaomiao Wang
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Fan Wu
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Heng Liu
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Department of Biomedical Engineering, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Qinli Sun
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Department of Biomedical Engineering, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
| | - Yuli Zhang
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Congcong Liu
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Chao Jin
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jian Yang
- Department of Radiology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.,Department of Biomedical Engineering, The Key Laboratory of Biomedical Information Engineering of the Ministry of Education, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an, China
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13
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The Neuromuscular Junction: Roles in Aging and Neuromuscular Disease. Int J Mol Sci 2021; 22:ijms22158058. [PMID: 34360831 PMCID: PMC8347593 DOI: 10.3390/ijms22158058] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 02/07/2023] Open
Abstract
The neuromuscular junction (NMJ) is a specialized synapse that bridges the motor neuron and the skeletal muscle fiber and is crucial for conversion of electrical impulses originating in the motor neuron to action potentials in the muscle fiber. The consideration of contributing factors to skeletal muscle injury, muscular dystrophy and sarcopenia cannot be restricted only to processes intrinsic to the muscle, as data show that these conditions incur denervation-like findings, such as fragmented NMJ morphology and corresponding functional changes in neuromuscular transmission. Primary defects in the NMJ also influence functional loss in motor neuron disease, congenital myasthenic syndromes and myasthenia gravis, resulting in skeletal muscle weakness and heightened fatigue. Such findings underscore the role that the NMJ plays in neuromuscular performance. Regardless of cause or effect, functional denervation is now an accepted consequence of sarcopenia and muscle disease. In this short review, we provide an overview of the pathologic etiology, symptoms, and therapeutic strategies related to the NMJ. In particular, we examine the role of the NMJ as a disease modifier and a potential therapeutic target in neuromuscular injury and disease.
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14
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Manto KM, Govindappa PK, Parisi D, Karuman Z, Martinazzi B, Hegarty JP, Talukder MAH, Elfar JC. (4-Aminopyridine)-PLGA-PEG as a Novel Thermosensitive and Locally Injectable Treatment for Acute Peripheral Nerve Injury. ACS APPLIED BIO MATERIALS 2021; 4:4140-4151. [PMID: 34142019 DOI: 10.1021/acsabm.0c01566] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Traumatic peripheral nerve injury (TPNI) represents a major medical problem that results in loss of motor and sensory function, and in severe cases, limb paralysis and amputation. To date, there are no effective treatments beyond surgery in selective cases. In repurposing studies, we found that daily systemic administration of the FDA-approved drug 4-aminopyridine (4-AP) enhanced functional recovery after acute peripheral nerve injury. This study was aimed at constructing a novel local delivery system of 4-AP using thermogelling polymers. We optimized a thermosensitive (4-AP)-poly(lactide-co-glycolide)-b-poly(ethylene glycol)-b-poly(lactide-co-glycolide) (PLGA-PEG-PLGA) block copolymer formulation. (4-AP)-PLGA-PEG exhibited controlled release of 4-AP both in vitro and in vivo for approximately 3 weeks, with clinically relevant safe serum levels in animals. Rheological investigation showed that (4-AP)-PLGA-PEG underwent a solution to gel transition at 32 °C, a physiologically relevant temperature, allowing us to administer it to an injured limb while subsequently forming an in situ gel. A single local administration of (4-AP)-PLGA-PEG remarkably enhanced motor and sensory functional recovery on post-sciatic nerve crush injury days 1, 3, 7, 14, and 21. Moreover, immunohistochemical studies of injured nerves treated with (4-AP)-PLGA-PEG demonstrated an increased expression of neurofilament heavy chain (NF-H) and myelin protein zero (MPZ) proteins, two major markers of nerve regeneration. These findings demonstrate that (4-AP)-PLGA-PEG may be a promising long-acting local therapeutic agent in TPNI, for which no pharmacologic treatment exists.
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Affiliation(s)
- Kristen M Manto
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
| | - Prem Kumar Govindappa
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
| | - Daniele Parisi
- Department of Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Zara Karuman
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
| | - Brandon Martinazzi
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
| | - John P Hegarty
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
| | - M A Hassan Talukder
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
| | - John C Elfar
- Department of Orthopaedics and Rehabilitation, Center for Orthopaedic Research and Translational Science, The Pennsylvania State University College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania 17033, United States
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15
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Prokop A. Cytoskeletal organization of axons in vertebrates and invertebrates. J Cell Biol 2021; 219:151734. [PMID: 32369543 PMCID: PMC7337489 DOI: 10.1083/jcb.201912081] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
The maintenance of axons for the lifetime of an organism requires an axonal cytoskeleton that is robust but also flexible to adapt to mechanical challenges and to support plastic changes of axon morphology. Furthermore, cytoskeletal organization has to adapt to axons of dramatically different dimensions, and to their compartment-specific requirements in the axon initial segment, in the axon shaft, at synapses or in growth cones. To understand how the cytoskeleton caters to these different demands, this review summarizes five decades of electron microscopic studies. It focuses on the organization of microtubules and neurofilaments in axon shafts in both vertebrate and invertebrate neurons, as well as the axon initial segments of vertebrate motor- and interneurons. Findings from these ultrastructural studies are being interpreted here on the basis of our contemporary molecular understanding. They strongly suggest that axon architecture in animals as diverse as arthropods and vertebrates is dependent on loosely cross-linked bundles of microtubules running all along axons, with only minor roles played by neurofilaments.
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Affiliation(s)
- Andreas Prokop
- School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, The University of Manchester, Manchester, UK
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16
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Bomont P. The dazzling rise of neurofilaments: Physiological functions and roles as biomarkers. Curr Opin Cell Biol 2021; 68:181-191. [PMID: 33454158 DOI: 10.1016/j.ceb.2020.10.011] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Revised: 10/13/2020] [Accepted: 10/19/2020] [Indexed: 12/15/2022]
Abstract
In the last two years, neurofilaments (NFs) have become one of the most blazing topics in clinical neuroscience. NFs are major cytoskeletal constituents of neurons, can be detected in body fluids, and have recently emerged as universal biomarkers of neuronal injury and neurological diseases. This review will examine the evolving landscape of NFs, from their specific cellular functions within neurons to their broad clinical value as biomarkers. Particular attention will be given to the dynamic nature of the NF network and its novel roles in microtubule regulation, neurotransmission, and nanomedicine. Building from the initial evidence of causative mutations in NF genes in Charcot-Marie-Tooth diseases, the latest advances at the frontiers of basic and clinical sciences have expanded the scope and relevance of NFs for human health remarkably and have poised to fuel innovation in cell biology and neuroscience.
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Affiliation(s)
- Pascale Bomont
- ERC team, INMG, INSERM U1217, CNRS UMR5310, University of Lyon 1, University of Lyon, Lyon, France.
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17
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Okan G, Baki AM, Yorulmaz E, Doğru-Abbasoğlu S, Vural P. A preliminary study about neurofilament light chain and tau protein levels in psoriasis: Correlation with disease severity. J Clin Lab Anal 2020; 35:e23564. [PMID: 32896023 PMCID: PMC7843295 DOI: 10.1002/jcla.23564] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/26/2020] [Accepted: 08/18/2020] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Studies investigating cognitive dysfunction in psoriatic patients remain inconclusive. OBJECTIVE To investigate the risk of cognitive decline in plaque-type psoriasis patients. METHODS Serum neurofilament light chain (NFL) and tau protein concentrations in 45 patients with plaque-type psoriasis and forty-five healthy controls were measured by enzyme-linked immunosorbent assay (ELISA). RESULTS Mean homeostasis model assessment (HOMA-IR) values (6.82 vs 3.25) and serum levels of insulin (28.19 vs 15.71), NFL (5.74 vs 1.98), and tau (348.17 vs 207.30) in patients with psoriasis were found to be significantly higher than those of in healthy controls. There was a significant positive correlation between NFL and tau (r = .257, P = .015). There was significant correlation between NFL, tau and PASI (r = .310, P = .040) and (r = .383, P = .010), respectively. Significant correlations between NFL and insulin, TC, HDL-C, TG, VLDL-C, and BMI were found. NFL (9.38 vs 3.08) and tau (439.28 vs 281.58) concentrations and PASI values (23.94 vs 14.18) in patients with disease onset before 40 years were significantly higher than that of the patients with disease onset after 40 years. C-reactive protein (CRP) was significantly correlated with BMI (r = .449, P < .001), LDL-C (r = .240, P = .026), TG (r = .244, P = .024), and VLDL-C (r = .241, P = .025) in patients with psoriasis. CONCLUSIONS Increased serum NFL and tau protein levels and the presence of positive correlations between NFL, tau protein and PASI score show cognitive decline risk may be higher in moderate-to-severe psoriasis.
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Affiliation(s)
- Gokhan Okan
- Department of Dermatology, Memorial Bahcelievler Hospital, Istanbul, Turkey
| | - Adile Merve Baki
- Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Eda Yorulmaz
- Department of Biochemistry, Memorial Bahcelievler Hospital, Istanbul, Turkey
| | - Semra Doğru-Abbasoğlu
- Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Pervin Vural
- Department of Biochemistry, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
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18
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Fenn JD, Monsma PC, Brown A. Axonal neurofilaments exhibit frequent and complex folding behaviors. Cytoskeleton (Hoboken) 2019; 75:258-280. [PMID: 29683261 DOI: 10.1002/cm.21448] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 03/30/2018] [Accepted: 04/03/2018] [Indexed: 01/19/2023]
Abstract
Neurofilaments are flexible cytoskeletal polymers that are capable of folding and unfolding between their bouts of bidirectional movement along axons. Here we present a detailed characterization of this behavior in cultured neurons using kymograph analysis with approximately 30 ms temporal resolution. We analyzed 781 filaments ranging from 0.6-42 µm in length. We observed complex behaviors including pinch folds, hairpin folds, orientation changes (flips), and occasional severing and annealing events. On average, the filaments spent approximately 40% of their time in some sort of folded configuration. A small proportion of filaments (4%) moved while folded, but most (96%) moved in an outstretched configuration. Collectively, our observations suggest that motors may interact with neurofilaments at multiple points along their length, but preferentially at their ends. In addition, the prevalence of neurofilament folding and the tendency of neurofilaments to straighten out when they move, suggest that an important function of the movement of these polymers in axons may be to maintain them in an outstretched and longitudinally co-aligned configuration. Thus, neurofilament movement may function as much to organize these polymers as to move them, and this could explain why they spend so much time engaged in apparently unproductive bidirectional movement.
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Affiliation(s)
- J Daniel Fenn
- Department of Neuroscience, Ohio State University, Columbus, Ohio, 43210.,Medical Scientist Training Program, Ohio State University, Columbus, Ohio, 43210
| | - Paula C Monsma
- Department of Neuroscience, Ohio State University, Columbus, Ohio, 43210
| | - Anthony Brown
- Department of Neuroscience, Ohio State University, Columbus, Ohio, 43210
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19
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Zolochevska O, Bjorklund N, Woltjer R, Wiktorowicz JE, Taglialatela G. Postsynaptic Proteome of Non-Demented Individuals with Alzheimer's Disease Neuropathology. J Alzheimers Dis 2019; 65:659-682. [PMID: 30103319 PMCID: PMC6130411 DOI: 10.3233/jad-180179] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Some individuals, here referred to as Non-Demented with Alzheimer’s Neuropathology (NDAN), retain their cognitive function despite the presence of amyloid plaques and tau tangles typical of symptomatic Alzheimer’s disease (AD). In NDAN, unlike AD, toxic amyloid-β oligomers do not localize to the postsynaptic densities (PSDs). Synaptic resistance to amyloid-β in NDAN may thus enable these individuals to remain cognitively intact despite the AD-like pathology. The mechanism(s) responsible for this resistance remains unresolved and understanding such protective biological processes could reveal novel targets for the development of effective treatments for AD. The present study uses a proteomic approach to compare the hippocampal postsynaptic densities of NDAN, AD, and healthy age-matched persons to identify protein signatures characteristic for these groups. Subcellular fractionation followed by 2D gel electrophoresis and mass spectrometry were used to analyze the PSDs. We describe fifteen proteins which comprise the unique proteomic signature of NDAN PSDs, thus setting them apart from control subjects and AD patients.
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Affiliation(s)
- Olga Zolochevska
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA
| | - Nicole Bjorklund
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA
| | - Randall Woltjer
- Department of Pathology, Oregon Health and Science University, Portland, OR, USA
| | - John E Wiktorowicz
- Department of Biochemistry and Molecular Biology, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, TX, USA
| | - Giulio Taglialatela
- Department of Neurology, University of Texas Medical Branch, Galveston, TX, USA
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20
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Malacrida A, Meregalli C, Rodriguez-Menendez V, Nicolini G. Chemotherapy-Induced Peripheral Neuropathy and Changes in Cytoskeleton. Int J Mol Sci 2019; 20:ijms20092287. [PMID: 31075828 PMCID: PMC6540147 DOI: 10.3390/ijms20092287] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 05/06/2019] [Accepted: 05/07/2019] [Indexed: 12/23/2022] Open
Abstract
Despite the different antineoplastic mechanisms of action, peripheral neurotoxicity induced by all chemotherapy drugs (anti-tubulin agents, platinum compounds, proteasome inhibitors, thalidomide) is associated with neuron morphological changes ascribable to cytoskeleton modifications. The “dying back” degeneration of distal terminals (sensory nerves) of dorsal root ganglia sensory neurons, observed in animal models, in in vitro cultures and biopsies of patients is the most evident hallmark of the perturbation of the cytoskeleton. On the other hand, in highly polarized cells like neurons, the cytoskeleton carries out its role not only in axons but also has a fundamental role in dendrite plasticity and in the organization of soma. In the literature, there are many studies focused on the antineoplastic-induced alteration of microtubule organization (and consequently, fast axonal transport defects) while very few studies have investigated the effect of the different classes of drugs on microfilaments, intermediate filaments and associated proteins. Therefore, in this review, we will focus on: (1) Highlighting the fundamental role of the crosstalk among the three filamentous subsystems and (2) investigating pivotal cytoskeleton-associated proteins.
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Affiliation(s)
- Alessio Malacrida
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
| | - Cristina Meregalli
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
| | - Virginia Rodriguez-Menendez
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
| | - Gabriella Nicolini
- School of Medicine and Surgery, Experimental Neurology Unit and Milan Center for Neuroscience, University of Milano-Bicocca, via Cadore 48, 20900 Monza, MB, Italy.
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21
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Zakaria M, Ferent J, Hristovska I, Laouarem Y, Zahaf A, Kassoussi A, Mayeur ME, Pascual O, Charron F, Traiffort E. The Shh receptor Boc is important for myelin formation and repair. Development 2019; 146:146/9/dev172502. [PMID: 31048318 DOI: 10.1242/dev.172502] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2018] [Accepted: 03/28/2019] [Indexed: 12/25/2022]
Abstract
Myelination leads to the formation of myelin sheaths surrounding neuronal axons and is crucial for function, plasticity and repair of the central nervous system (CNS). It relies on the interaction of the axons and the oligodendrocytes: the glial cells producing CNS myelin. Here, we have investigated the role of a crucial component of the Sonic hedgehog (Shh) signalling pathway, the co-receptor Boc, in developmental and repairing myelination. During development, Boc mutant mice display a transient decrease in oligodendroglial cell density together with delayed myelination. Despite recovery of oligodendroglial cells at later stages, adult mutants still exhibit a lower production of myelin basic protein correlated with a significant decrease in the calibre of callosal axons and a reduced amount of the neurofilament NF-M. During myelin repair, the altered OPC differentiation observed in the mutant is reminiscent of the phenotype observed after blockade of Shh signalling. In addition, Boc mutant microglia/macrophages unexpectedly exhibit the apparent inability to transition from a highly to a faintly ramified morphology in vivo Altogether, these results identify Boc as an important component of myelin formation and repair.
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Affiliation(s)
- Mary Zakaria
- INSERM-University Paris-Sud/Paris-Saclay; Diseases and Hormones of the Nervous System, U1195, 80 rue du Général Leclerc, F-94276, Le Kremlin-Bicêtre, France
| | - Julien Ferent
- IRCM, Molecular Biology of Neural Development, 110 Pine Avenue West, Montreal, Quebec H2W 1R7, Canada; Department of Medicine, University of Montreal, Montreal, Quebec, Canada; McGill University, Montreal, Quebec, Canada
| | - Ines Hristovska
- Institut NeuroMyoGène CNRS UMR 5310-INSERM U1217-Université Claude Bernard Lyon 1, Faculté de Médecine et de Pharmacie 69008 Lyon, France
| | - Yousra Laouarem
- INSERM-University Paris-Sud/Paris-Saclay; Diseases and Hormones of the Nervous System, U1195, 80 rue du Général Leclerc, F-94276, Le Kremlin-Bicêtre, France
| | - Amina Zahaf
- INSERM-University Paris-Sud/Paris-Saclay; Diseases and Hormones of the Nervous System, U1195, 80 rue du Général Leclerc, F-94276, Le Kremlin-Bicêtre, France
| | - Abdelmoumen Kassoussi
- INSERM-University Paris-Sud/Paris-Saclay; Diseases and Hormones of the Nervous System, U1195, 80 rue du Général Leclerc, F-94276, Le Kremlin-Bicêtre, France
| | - Marie-Eve Mayeur
- Institut NeuroMyoGène CNRS UMR 5310-INSERM U1217-Université Claude Bernard Lyon 1, Faculté de Médecine et de Pharmacie 69008 Lyon, France
| | - Olivier Pascual
- Institut NeuroMyoGène CNRS UMR 5310-INSERM U1217-Université Claude Bernard Lyon 1, Faculté de Médecine et de Pharmacie 69008 Lyon, France
| | - Frederic Charron
- IRCM, Molecular Biology of Neural Development, 110 Pine Avenue West, Montreal, Quebec H2W 1R7, Canada; Department of Medicine, University of Montreal, Montreal, Quebec, Canada; McGill University, Montreal, Quebec, Canada
| | - Elisabeth Traiffort
- INSERM-University Paris-Sud/Paris-Saclay; Diseases and Hormones of the Nervous System, U1195, 80 rue du Général Leclerc, F-94276, Le Kremlin-Bicêtre, France
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22
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Villalón E, Barry DM, Byers N, Frizzi K, Jones MR, Landayan DS, Dale JM, Downer NL, Calcutt NA, Garcia ML. Internode length is reduced during myelination and remyelination by neurofilament medium phosphorylation in motor axons. Exp Neurol 2018; 306:158-168. [PMID: 29772247 PMCID: PMC5994378 DOI: 10.1016/j.expneurol.2018.05.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Revised: 05/03/2018] [Accepted: 05/09/2018] [Indexed: 01/04/2023]
Abstract
The distance between nodes of Ranvier, referred to as internode length, positively correlates with axon diameter, and is optimized during development to ensure maximal neuronal conduction velocity. Following myelin loss, internode length is reestablished through remyelination. However, remyelination results in short internode lengths and reduced conduction rates. We analyzed the potential role of neurofilament phosphorylation in regulating internode length during remyelination and myelination. Following ethidium bromide induced demyelination, levels of neurofilament medium (NF-M) and heavy (NF-H) phosphorylation were unaffected. Preventing NF-M lysine-serine-proline (KSP) repeat phosphorylation increased internode length by 30% after remyelination. To further analyze the role of NF-M phosphorylation in regulating internode length, gene replacement was used to produce mice in which all KSP serine residues were replaced with glutamate to mimic constitutive phosphorylation. Mimicking constitutive KSP phosphorylation reduced internode length by 16% during myelination and motor nerve conduction velocity by ~27% without altering sensory nerve structure or function. Our results suggest that NF-M KSP phosphorylation is part of a cooperative mechanism between axons and Schwann cells that together determine internode length, and suggest motor and sensory axons utilize different mechanisms to establish internode length.
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Affiliation(s)
- Eric Villalón
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States
| | - Devin M Barry
- Department of Anesthesiology, Center for the Study of Itch, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - Nathan Byers
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, United States
| | - Katie Frizzi
- Department of Pathology, University of California San Diego, La Jolla, CA 92093, United States
| | - Maria R Jones
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States
| | - Dan S Landayan
- Department of Quantitative and Systems Biology, University of California Merced, Merced, CA 95343, United States
| | - Jeffrey M Dale
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States
| | - Natalie L Downer
- Department of Biological Science, Moberly Area Community College, Moberly, MO 65270, United States
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA 92093, United States
| | - Michael L Garcia
- Department of Biological Sciences, University of Missouri, Columbia, MO 65211, United States; C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, United States.
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23
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Lavelle C, Smith LC, Bisesi JH, Yu F, Silva-Sanchez C, Moraga-Amador D, Buerger AN, Garcia-Reyero N, Sabo-Attwood T, Denslow ND. Tissue-Based Mapping of the Fathead Minnow ( Pimephales promelas) Transcriptome and Proteome. Front Endocrinol (Lausanne) 2018; 9:611. [PMID: 30459712 PMCID: PMC6232228 DOI: 10.3389/fendo.2018.00611] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 09/26/2018] [Indexed: 12/11/2022] Open
Abstract
Omics approaches are broadly used to explore endocrine and toxicity-related pathways and functions. Nevertheless, there is still a significant gap in knowledge in terms of understanding the endocrine system and its numerous connections and intricate feedback loops, especially in non-model organisms. The fathead minnow (Pimephales promelas) is a widely used small fish model for aquatic toxicology and regulatory testing, particularly in North America. A draft genome has been published, but the amount of available genomic or transcriptomic information is still far behind that of other more broadly studied species, such as the zebrafish. Here, we used a proteogenomics approach to survey the tissue-specific proteome and transcriptome profiles in adult male fathead minnow. To do so, we generated a draft transcriptome using short and long sequencing reads from liver, testis, brain, heart, gill, head kidney, trunk kidney, and gastrointestinal tract. We identified 30,378 different putative transcripts overall, with the assembled contigs ranging in size from 264 to over 9,720 nts. Over 17,000 transcripts were >1,000 nts, suggesting a robust transcriptome that can be used to interpret RNA sequencing data in the future. We also performed RNA sequencing and proteomics analysis on four tissues, including the telencephalon, hypothalamus, liver, and gastrointestinal tract of male fish. Transcripts ranged from 0 to 600,000 copies per gene and a large portion were expressed in a tissue-specific manner. Specifically, the telencephalon and hypothalamus shared the most expressed genes, while the gastrointestinal tract and the liver were quite distinct. Using protein profiling techniques, we identified a total of 4,045 proteins in the four tissues investigated, and their tissue-specific expression pattern correlated with the transcripts at the pathway level. Similarly to the findings with the transcriptomic data, the hypothalamus and telencephalon had the highest degree of similarity in the proteins detected. The main purpose of this analysis was to generate tissue-specific omics data in order to support future aquatic ecotoxicogenomic and endocrine-related studies as well as to improve our understanding of the fathead minnow as an ecological model.
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Affiliation(s)
- Candice Lavelle
- Department of Environmental and Global Health, University of Florida, Gainesville, FL, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
| | - Ley Cody Smith
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
- Department of Physiological Sciences, University of Florida, Gainesville, FL, United States
| | - Joseph H. Bisesi
- Department of Environmental and Global Health, University of Florida, Gainesville, FL, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
| | - Fahong Yu
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States
| | - Cecilia Silva-Sanchez
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States
| | - David Moraga-Amador
- Interdisciplinary Center for Biotechnology Research, University of Florida, Gainesville, FL, United States
| | - Amanda N. Buerger
- Department of Environmental and Global Health, University of Florida, Gainesville, FL, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
| | - Natàlia Garcia-Reyero
- Environmental Laboratory, US Army Engineer Research & Development Center, Vicksburg, MS, United States
| | - Tara Sabo-Attwood
- Department of Environmental and Global Health, University of Florida, Gainesville, FL, United States
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
| | - Nancy D. Denslow
- Center for Environmental and Human Toxicology, University of Florida, Gainesville, FL, United States
- Department of Physiological Sciences, University of Florida, Gainesville, FL, United States
- *Correspondence: Nancy D. Denslow
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24
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Pan S, Chan JR. Regulation and dysregulation of axon infrastructure by myelinating glia. J Cell Biol 2017; 216:3903-3916. [PMID: 29114067 PMCID: PMC5716274 DOI: 10.1083/jcb.201702150] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/06/2017] [Accepted: 10/18/2017] [Indexed: 12/21/2022] Open
Abstract
Pan and Chan discuss the role of myelinating glia in axonal development and the impact of demyelination on axon degeneration. Axon loss and neurodegeneration constitute clinically debilitating sequelae in demyelinating diseases such as multiple sclerosis, but the underlying mechanisms of secondary degeneration are not well understood. Myelinating glia play a fundamental role in promoting the maturation of the axon cytoskeleton, regulating axon trafficking parameters, and imposing architectural rearrangements such as the nodes of Ranvier and their associated molecular domains. In the setting of demyelination, these changes may be reversed or persist as maladaptive features, leading to axon degeneration. In this review, we consider recent insights into axon–glial interactions during development and disease to propose that disruption of the cytoskeleton, nodal architecture, and other components of axon infrastructure is a potential mediator of pathophysiological damage after demyelination.
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Affiliation(s)
- Simon Pan
- Department of Neurology, University of California, San Francisco, San Francisco, CA .,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Jonah R Chan
- Department of Neurology, University of California, San Francisco, San Francisco, CA.,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
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25
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George C, Gontier G, Lacube P, François JC, Holzenberger M, Aïd S. The Alzheimer's disease transcriptome mimics the neuroprotective signature of IGF-1 receptor-deficient neurons. Brain 2017; 140:2012-2027. [PMID: 28595357 DOI: 10.1093/brain/awx132] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 04/12/2017] [Indexed: 12/22/2022] Open
Abstract
Seminal studies using post-mortem brains of patients with Alzheimer's disease evidenced aberrant insulin-like growth factor 1 receptor (IGF1R) signalling. Addressing causality, work in animal models recently demonstrated that long-term suppression of IGF1R signalling alleviates Alzheimer's disease progression and promotes neuroprotection. However, the underlying mechanisms remain largely elusive. Here, we showed that genetically ablating IGF1R in neurons of the ageing brain efficiently protects from neuroinflammation, anxiety and memory impairments induced by intracerebroventricular injection of amyloid-β oligomers. In our mutant mice, the suppression of IGF1R signalling also invariably led to small neuronal soma size, indicative of profound changes in cellular homeodynamics. To gain insight into transcriptional signatures leading to Alzheimer's disease-relevant neuronal defence, we performed genome-wide microarray analysis on laser-dissected hippocampal CA1 after neuronal IGF1R knockout, in the presence or absence of APP/PS1 transgenes. Functional analysis comparing neurons in early-stage Alzheimer's disease with IGF1R knockout neurons revealed strongly convergent transcriptomic signatures, notably involving neurite growth, cytoskeleton organization, cellular stress response and neurotransmission. Moreover, in Alzheimer's disease neurons, a high proportion of genes responding to Alzheimer's disease showed a reversed differential expression when IGF1R was deleted. One of the genes consistently highlighted in genome-wide comparison was the neurofilament medium polypeptide Nefm. We found that NEFM accumulated in hippocampus in the presence of amyloid pathology, and decreased to control levels under IGF1R deletion, suggesting that reorganized cytoskeleton likely plays a role in neuroprotection. These findings demonstrated that significant resistance of the brain to amyloid-β can be achieved lifelong by suppressing neuronal IGF1R and identified IGF-dependent molecular pathways that coordinate an intrinsic program for neuroprotection against proteotoxicity. Our data also indicate that neuronal defences against Alzheimer's disease rely on an endogenous gene expression profile similar to the neuroprotective response activated by genetic disruption of IGF1R signalling. This study highlights neuronal IGF1R signalling as a relevant target for developing Alzheimer's disease prevention strategies.
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Affiliation(s)
- Caroline George
- INSERM, Centre de Recherche Saint-Antoine, 75012 Paris, France.,Sorbonne Universités, UPMC - Université Pierre et Marie Curie, 75012 Paris, France
| | - Géraldine Gontier
- INSERM, Centre de Recherche Saint-Antoine, 75012 Paris, France.,Sorbonne Universités, UPMC - Université Pierre et Marie Curie, 75012 Paris, France
| | - Philippe Lacube
- INSERM, Centre de Recherche Saint-Antoine, 75012 Paris, France.,Sorbonne Universités, UPMC - Université Pierre et Marie Curie, 75012 Paris, France
| | - Jean-Christophe François
- INSERM, Centre de Recherche Saint-Antoine, 75012 Paris, France.,Sorbonne Universités, UPMC - Université Pierre et Marie Curie, 75012 Paris, France
| | - Martin Holzenberger
- INSERM, Centre de Recherche Saint-Antoine, 75012 Paris, France.,Sorbonne Universités, UPMC - Université Pierre et Marie Curie, 75012 Paris, France
| | - Saba Aïd
- INSERM, Centre de Recherche Saint-Antoine, 75012 Paris, France.,Sorbonne Universités, UPMC - Université Pierre et Marie Curie, 75012 Paris, France
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26
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Kirkcaldie MTK, Dwyer ST. The third wave: Intermediate filaments in the maturing nervous system. Mol Cell Neurosci 2017; 84:68-76. [PMID: 28554564 DOI: 10.1016/j.mcn.2017.05.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Revised: 05/10/2017] [Accepted: 05/25/2017] [Indexed: 01/16/2023] Open
Abstract
Intermediate filaments are critical for the extreme structural specialisations of neurons, providing integrity in dynamic environments and efficient communication along axons a metre or more in length. As neurons mature, an initial expression of nestin and vimentin gives way to the neurofilament triplet proteins and α-internexin, substituted by peripherin in axons outside the CNS, which physically consolidate axons as they elongate and find their targets. Once connection is established, these proteins are transported, assembled, stabilised and modified, structurally transforming axons and dendrites as they acquire their full function. The interaction between these neurons and myelinating glial cells optimises the structure of axons for peak functional efficiency, a property retained across their lifespan. This finely calibrated structural regulation allows the nervous system to maintain timing precision and efficient control across large distances throughout somatic growth and, in maturity, as a plasticity mechanism allowing functional adaptation.
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Affiliation(s)
- Matthew T K Kirkcaldie
- School of Medicine, Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia.
| | - Samuel T Dwyer
- School of Medicine, Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia
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27
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Jones MR, Villalón E, Northcutt AJ, Calcutt NA, Garcia ML. Differential effects of myostatin deficiency on motor and sensory axons. Muscle Nerve 2017; 56:E100-E107. [PMID: 28073155 DOI: 10.1002/mus.25570] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Revised: 01/04/2017] [Accepted: 01/08/2017] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Deletion of myostatin in mice (MSTN-/- ) alters structural properties of peripheral axons. However, properties like axon diameter and myelin thickness were analyzed in mixed nerves, so it is unclear whether loss of myostatin affects motor, sensory, or both types of axons. METHODS Using the MSTN-/- mouse model, we analyzed the effects of increasing the number of muscle fibers on axon diameter, myelin thickness, and internode length in motor and sensory axons. RESULTS Axon diameter and myelin thickness were increased in motor axons of MSTN-/- mice without affecting internode length or axon number. The number of sensory axons was increased without affecting their structural properties. DISCUSSION These results suggest that motor and sensory axons establish structural properties by independent mechanisms. Moreover, in motor axons, instructive cues from the neuromuscular junction may play a role in co-regulating axon diameter and myelin thickness, whereas internode length is established independently. Muscle Nerve 56: E100-E107, 2017.
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Affiliation(s)
- Maria R Jones
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA.,C.S. Bond Life Sciences Center, University of Missouri, 1201 East Rollins Road, Columbia, Missouri, 65211, USA
| | - Eric Villalón
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA.,C.S. Bond Life Sciences Center, University of Missouri, 1201 East Rollins Road, Columbia, Missouri, 65211, USA
| | - Adam J Northcutt
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, California, USA
| | - Michael L Garcia
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA.,C.S. Bond Life Sciences Center, University of Missouri, 1201 East Rollins Road, Columbia, Missouri, 65211, USA
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28
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Yuan A, Rao MV, Veeranna, Nixon RA. Neurofilaments and Neurofilament Proteins in Health and Disease. Cold Spring Harb Perspect Biol 2017; 9:9/4/a018309. [PMID: 28373358 DOI: 10.1101/cshperspect.a018309] [Citation(s) in RCA: 408] [Impact Index Per Article: 58.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
SUMMARYNeurofilaments (NFs) are unique among tissue-specific classes of intermediate filaments (IFs) in being heteropolymers composed of four subunits (NF-L [neurofilament light]; NF-M [neurofilament middle]; NF-H [neurofilament heavy]; and α-internexin or peripherin), each having different domain structures and functions. Here, we review how NFs provide structural support for the highly asymmetric geometries of neurons and, especially, for the marked radial expansion of myelinated axons crucial for effective nerve conduction velocity. NFs in axons extensively cross-bridge and interconnect with other non-IF components of the cytoskeleton, including microtubules, actin filaments, and other fibrous cytoskeletal elements, to establish a regionally specialized network that undergoes exceptionally slow local turnover and serves as a docking platform to organize other organelles and proteins. We also discuss how a small pool of oligomeric and short filamentous precursors in the slow phase of axonal transport maintains this network. A complex pattern of phosphorylation and dephosphorylation events on each subunit modulates filament assembly, turnover, and organization within the axonal cytoskeleton. Multiple factors, and especially turnover rate, determine the size of the network, which can vary substantially along the axon. NF gene mutations cause several neuroaxonal disorders characterized by disrupted subunit assembly and NF aggregation. Additional NF alterations are associated with varied neuropsychiatric disorders. New evidence that subunits of NFs exist within postsynaptic terminal boutons and influence neurotransmission suggests how NF proteins might contribute to normal synaptic function and neuropsychiatric disease states.
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Affiliation(s)
- Aidong Yuan
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016
| | - Mala V Rao
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016
| | - Veeranna
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016
| | - Ralph A Nixon
- Center for Dementia Research, Nathan Kline Institute, Orangeburg, New York 10962.,Department of Psychiatry, New York University School of Medicine, New York, New York 10016.,Cell Biology, New York University School of Medicine, New York, New York 10016
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29
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Han Q, Lin Q, Huang P, Chen M, Hu X, Fu H, He S, Shen F, Zeng H, Deng Y. Microglia-derived IL-1β contributes to axon development disorders and synaptic deficit through p38-MAPK signal pathway in septic neonatal rats. J Neuroinflammation 2017; 14:52. [PMID: 28288671 PMCID: PMC5348817 DOI: 10.1186/s12974-017-0805-x] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 01/26/2017] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Axon development plays a pivotal role in the formation of synapse, nodes of Ranvier, and myelin sheath. Interleukin-1β (IL-1β) produced by microglia may cause myelination disturbances through suppression of oligodendrocyte progenitor cell maturation in the septic neonatal rats. Here, we explored if a microglia-derived IL-1β would disturb axon development in the corpus callosum (CC) following lipopolysaccharide (LPS) administration, and if so, whether it is associated with disorder of synapse formation in the cerebral cortex and node of Ranvier. METHODS Sprague-Dawley rats (1-day old) in the septic model group were intraperitoneally administrated with lipopolysaccharide (1 mg/kg) and then sacrificed for detection of IL-1β, interleukin-1 receptor (IL-1R1), neurofilament-68, neurofilament-160, and neurofilament-200, proteolipid, synaptophysin, and postsynaptic density 95 (PSD95) expression by western blotting and immunofluorescence. Electron microscopy was conducted to observe alterations of axonal myelin sheath and synapses in the cortex, and proteolipid expression was assessed using in situ hybridization. The effect of IL-1β on neurofilament and synaptophysin expression in primary neuron cultures was determined by western blotting and immunofluorescence. P38-MAPK signaling pathway was investigated to determine whether it was involved in the inhibition of IL-1β on neurofilament and synaptophysin expression. RESULTS In 1-day old septic rats, IL-1β expression was increased in microglia coupled with upregulated expression of IL-1R1 on the axons. The expression of neurofilament-68, neurofilament-160, and neurofilament-200 (NFL, NFM, NFH) and proteolipid (PLP) was markedly reduced in the CC at 7, 14, and 28 days after LPS administration. Simultaneously, cortical synapses and mature oligodendrocytes were significantly reduced. By electron microscopy, some axons showed smaller diameter and thinner myelin sheath with damaged ultrastructure of node of Ranvier compared with the control rats. In the cerebral cortex of LPS-injected rats, some axo-dendritic synapses appeared abnormal looking as manifested by the presence of swollen and clumping of synaptic vesicles near the presynaptic membrane. In primary cultured neurons incubated with IL-1β, expression of NFL, NFM, and synaptophysin was significantly downregulated. Furthermore, p38-MAPK signaling pathway was implicated in disorder of axon development and synaptic deficit caused by IL-1β treatment. CONCLUSIONS The present results suggest that microglia-derived IL-1β might suppress axon development through activation of p38-MAPK signaling pathway that would contribute to formation disorder of cortical synapses and node of Ranvier following LPS exposure.
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Affiliation(s)
- Qianpeng Han
- Southern Medical University, Guangzhou, 510515 People’s Republic of China
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
- Department of Critical Care Medicine, Yueyang First People’s Hospital, Yueyang, 414000 People’s Republic of China
| | - Qiongyu Lin
- Southern Medical University, Guangzhou, 510515 People’s Republic of China
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
| | - Peixian Huang
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
- Shantou University Medical College, Shantou, Guangdong 515063 People’s Republic of China
| | - Mengmeng Chen
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
- Shantou University Medical College, Shantou, Guangdong 515063 People’s Republic of China
| | - Xin Hu
- Department of Anatomy, Basic medical school of Wuhan University, Wuhan, Hubei 430071 People’s Republic of China
| | - Hui Fu
- Department of Anatomy, Basic medical school of Wuhan University, Wuhan, Hubei 430071 People’s Republic of China
| | - Shaoru He
- Department of Neonatology, Guangzhou General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
| | - Fengcai Shen
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
- Shantou University Medical College, Shantou, Guangdong 515063 People’s Republic of China
| | - Hongke Zeng
- Southern Medical University, Guangzhou, 510515 People’s Republic of China
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
| | - Yiyu Deng
- Southern Medical University, Guangzhou, 510515 People’s Republic of China
- Department of Critical Care and Emergency, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, 510080 People’s Republic of China
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30
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31
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Compagnucci C, Piermarini E, Sferra A, Borghi R, Niceforo A, Petrini S, Piemonte F, Bertini E. Cytoskeletal dynamics during in vitro neurogenesis of induced pluripotent stem cells (iPSCs). Mol Cell Neurosci 2016; 77:113-124. [PMID: 27756615 DOI: 10.1016/j.mcn.2016.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/24/2016] [Accepted: 10/13/2016] [Indexed: 12/27/2022] Open
Abstract
Patient-derived induced pluripotent stem cells (iPSCs) provide a novel tool to investigate the pathophysiology of poorly known diseases, in particular those affecting the nervous system, which has been difficult to study for its lack of accessibility. In this emerging and promising field, recent iPSCs studies are mostly used as "proof-of-principle" experiments that are confirmatory of previous findings obtained from animal models and postmortem human studies; its promise as a discovery tool is just beginning to be realized. A recent number of studies point to the functional similarities between in vitro neurogenesis and in vivo neuronal development, suggesting that similar morphogenetic and patterning events direct neuronal differentiation. In this context, neuronal adhesion, cytoskeletal organization and cell metabolism emerge as an integrated and unexplored processes of human neurogenesis, mediated by the lack of data due to the difficult accessibility of the human neural tissue. These observations raise the necessity to understand which are the players controlling cytoskeletal reorganization and remodeling. In particular, we investigated human in vitro neurogenesis using iPSCs of healthy subjects to unveil the underpinnings of the cytoskeletal dynamics with the aim to shed light on the physiologic events controlling the development and the functionality of neuronal cells. We validate the iPSCs system to better understand the development of the human nervous system in order to set the bases for the future understanding of pathologies including developmental disorders (i.e. intellectual disability), epilepsy but also neurodegenerative disorders (i.e. Friedreich's Ataxia). We investigate the changes of the cytoskeletal components during the 30days of neuronal differentiation and we demonstrate that human neuronal differentiation requires a (time-dependent) reorganization of actin filaments, intermediate filaments and microtubules; and that immature neurons present a finely regulated localization of Glu-, Tyr- and Acet-TUBULINS. This study advances our understanding on cytoskeletal dynamics with the hope to pave the way for future therapies that could be potentially able to target cytoskeletal based neurodevelopmental and neurodegenerative diseases.
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Affiliation(s)
- Claudia Compagnucci
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy.
| | - Emanuela Piermarini
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy
| | - Antonella Sferra
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy
| | - Rossella Borghi
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy
| | - Alessia Niceforo
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy
| | - Stefania Petrini
- Confocal Microscopy Core Facility, Research Laboratories, Bambino Gesù Children's Hospital, IRCCS, Rome 00146, Italy
| | - Fiorella Piemonte
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy
| | - Enrico Bertini
- Department of Neuroscience, Unit of Neuromuscular and Neurodegenerative Diseases, Children's Research Hospital Bambino Gesù, IRCCS, Rome 00146, Italy
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32
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Vickers J, Kirkcaldie M, Phipps A, King A. Alterations in neurofilaments and the transformation of the cytoskeleton in axons may provide insight into the aberrant neuronal changes of Alzheimer’s disease. Brain Res Bull 2016; 126:324-333. [DOI: 10.1016/j.brainresbull.2016.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 01/09/2023]
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33
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Roda RH, FitzGibbon EJ, Boucekkine H, Schindler AB, Blackstone C. Neurologic syndrome associated with homozygous mutation at MAG sialic acid binding site. Ann Clin Transl Neurol 2016; 3:650-4. [PMID: 27606346 PMCID: PMC4999596 DOI: 10.1002/acn3.329] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 05/26/2016] [Accepted: 05/31/2016] [Indexed: 01/08/2023] Open
Abstract
The MAG gene encodes myelin-associated glycoprotein (MAG), an abundant protein involved in axon-glial interactions and myelination during nerve regeneration. Several members of a consanguineous family with a clinical syndrome reminiscent of Pelizaeus-Merzbacher disease and demyelinating leukodystrophy on brain MRI were recently found to harbor a homozygous missense p.Ser133Arg MAG mutation. Here, we report two brothers from a nonconsanguineous family afflicted with progressive cognitive impairment, neuropathy, ataxia, nystagmus, and gait disorder. Exome sequencing revealed the homozygous missense mutation p.Arg118His in MAG. This Arg118 residue in immunoglobulin domain 1 is critical for sialic acid binding, providing a compelling mechanistic basis for disease pathogenesis.
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Affiliation(s)
- Ricardo H Roda
- Department of Neurology Neuromuscular Medicine Johns Hopkins University School of Medicine Baltimore Maryland; Neurogenetics Branch National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda Maryland
| | - Edmond J FitzGibbon
- Laboratory of Sensorimotor Research National Eye Institute National Institutes of Health Bethesda Maryland
| | - Houda Boucekkine
- Neurogenetics Branch National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda Maryland
| | - Alice B Schindler
- Neurogenetics Branch National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda Maryland
| | - Craig Blackstone
- Neurogenetics Branch National Institute of Neurological Disorders and Stroke National Institutes of Health Bethesda Maryland
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34
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Rao SNR, Pearse DD. Regulating Axonal Responses to Injury: The Intersection between Signaling Pathways Involved in Axon Myelination and The Inhibition of Axon Regeneration. Front Mol Neurosci 2016; 9:33. [PMID: 27375427 PMCID: PMC4896923 DOI: 10.3389/fnmol.2016.00033] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Accepted: 05/02/2016] [Indexed: 01/06/2023] Open
Abstract
Following spinal cord injury (SCI), a multitude of intrinsic and extrinsic factors adversely affect the gene programs that govern the expression of regeneration-associated genes (RAGs) and the production of a diversity of extracellular matrix molecules (ECM). Insufficient RAG expression in the injured neuron and the presence of inhibitory ECM at the lesion, leads to structural alterations in the axon that perturb the growth machinery, or form an extraneous barrier to axonal regeneration, respectively. Here, the role of myelin, both intact and debris, in antagonizing axon regeneration has been the focus of numerous investigations. These studies have employed antagonizing antibodies and knockout animals to examine how the growth cone of the re-growing axon responds to the presence of myelin and myelin-associated inhibitors (MAIs) within the lesion environment and caudal spinal cord. However, less attention has been placed on how the myelination of the axon after SCI, whether by endogenous glia or exogenously implanted glia, may alter axon regeneration. Here, we examine the intersection between intracellular signaling pathways in neurons and glia that are involved in axon myelination and axon growth, to provide greater insight into how interrogating this complex network of molecular interactions may lead to new therapeutics targeting SCI.
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Affiliation(s)
- Sudheendra N R Rao
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine Miami, FL, USA
| | - Damien D Pearse
- The Miami Project to Cure Paralysis, University of Miami Miller School of MedicineMiami, FL, USA; The Department of Neurological Surgery, University of Miami Miller School of MedicineMiami, FL, USA; The Neuroscience Program, University of Miami Miller School of MedicineMiami, FL, USA; The Interdisciplinary Stem Cell Institute, University of Miami Miller School of MedicineMiami, FL, USA; Bruce W. Carter Department of Veterans Affairs Medical CenterMiami, FL, USA
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35
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Kirkcaldie MTK, Collins JM. The axon as a physical structure in health and acute trauma. J Chem Neuroanat 2016; 76:9-18. [PMID: 27233660 DOI: 10.1016/j.jchemneu.2016.05.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Revised: 05/22/2016] [Accepted: 05/22/2016] [Indexed: 10/21/2022]
Abstract
The physical structure of neurons - dendrites converging on the soma, with an axon conveying activity to distant locations - is uniquely tied to their function. To perform their role, axons need to maintain structural precision in the soft, gelatinous environment of the central nervous system and the dynamic, flexible paths of nerves in the periphery. This requires close mechanical coupling between axons and the surrounding tissue, as well as an elastic, robust axoplasm resistant to pinching and flattening, and capable of sustaining transport despite physical distortion. These mechanical properties arise primarily from the properties of the internal cytoskeleton, coupled to the axonal membrane and the extracellular matrix. In particular, the two large constituents of the internal cytoskeleton, microtubules and neurofilaments, are braced against each other and flexibly interlinked by specialised proteins. Recent evidence suggests that the primary function of neurofilament sidearms is to structure the axoplasm into a linearly organised, elastic gel. This provides support and structure to the contents of axons in peripheral nerves subject to bending, protecting the relatively brittle microtubule bundles and maintaining them as transport conduits. Furthermore, a substantial proportion of axons are myelinated, and this thick jacket of membrane wrappings alters the form, function and internal composition of the axons to which it is applied. Together these structures determine the physical properties and integrity of neural tissue, both under conditions of normal movement, and in response to physical trauma. The effects of traumatic injury are directly dependent on the physical properties of neural tissue, especially axons, and because of axons' extreme structural specialisation, post-traumatic effects are usually characterised by particular modes of axonal damage. The physical realities of axons in neural tissue are integral to both normal function and their response to injury, and require specific consideration in evaluating research models of neurotrauma.
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Affiliation(s)
- Matthew T K Kirkcaldie
- School of Medicine, University of Tasmania, Australia; Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia.
| | - Jessica M Collins
- Wicking Dementia Research and Education Centre, Faculty of Health, University of Tasmania, Australia
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36
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Seidl AH, Rubel EW. Systematic and differential myelination of axon collaterals in the mammalian auditory brainstem. Glia 2016; 64:487-94. [PMID: 26556176 PMCID: PMC4752408 DOI: 10.1002/glia.22941] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 10/20/2015] [Indexed: 12/19/2022]
Abstract
A brainstem circuit for encoding the spatial location of sounds involves neurons in the cochlear nucleus that project to medial superior olivary (MSO) neurons on both sides of the brain via a single bifurcating axon. Neurons in MSO act as coincidence detectors, responding optimally when signals from the two ears arrive within a few microseconds. To achieve this, transmission of signals along the contralateral collateral must be faster than transmission of the same signals along the ipsilateral collateral. We demonstrate that this is achieved by differential regulation of myelination and axon caliber along the ipsilateral and contralateral branches of single axons; ipsilateral axon branches have shorter internode lengths and smaller caliber than contralateral branches. The myelination difference is established prior to the onset of hearing. We conclude that this differential myelination and axon caliber requires local interactions between axon collaterals and surrounding oligodendrocytes on the two sides of the brainstem.
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Affiliation(s)
- Armin H. Seidl
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA
- Department of Neurology, University of Washington, Seattle, WA
| | - Edwin W Rubel
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA
- Department of Otolaryngology – Head & Neck Surgery, University of Washington, Seattle, WA
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Deek J, Chung PJ, Safinya CR. Neurofilament networks: Salt-responsive hydrogels with sidearm-dependent phase behavior. Biochim Biophys Acta Gen Subj 2016; 1860:1560-9. [PMID: 26993199 DOI: 10.1016/j.bbagen.2016.03.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 02/28/2016] [Accepted: 03/11/2016] [Indexed: 10/22/2022]
Abstract
BACKGROUND Neurofilaments (NFs) - the neuron-specific intermediate filament proteins - are assembled into 10nm wide filaments in a tightly controlled ratio of three different monomer types: NF-Low (NF-L), NF-Medium (NF-M), and NF-High (NF-H). Previous work on reconstituted bovine NF hydrogels has shown the dependence of network properties, including filament alignment and spacing, on the subunit composition. METHODS We use polarized optical microscopy and SAXS to explore the full salt-dependent phase behavior of reconstituted bovine NF networks as a function of various binary and ternary subunit ratios. RESULTS We observe three salt-induced liquid crystalline phases: the liquid-ordered B(G) and N(G) phases, and the disordered I(G) phase. We note the emergent sidearm roles, particularly that of NF-H in driving the parallel to cross-filament transition, and the counter-role of NF-M in suppressing the I(G) phase. CONCLUSIONS In copolymers of NF-LH, NF-H shifts the I(G) to N(G) transition to nearer physiological salt concentrations, as compared to NF-M in copolymers of NF-LM. For ternary mixtures, the role of NF-H is modulated by the ratio of NF-M, where beneath 10wt.% NF-M, NF-H drives the transition to the disordered phase, and above which NF-H increases interfilament spacing. GENERAL SIGNIFICANCE Understanding the role of individual subunits in regulating the network structure will enable us to understand the mechanisms that drive the dysfunction of these networks, as observed in diseased conditions.
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Affiliation(s)
- Joanna Deek
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106, United States.
| | - Peter J Chung
- Department of Physics, University of California, Santa Barbara, CA 93106, United States; Department of Materials, University of California, Santa Barbara, CA 93106, United States; Department of Molecular, Cellular, & Developmental Biology, University of California, Santa Barbara, CA 93106, United States.
| | - Cyrus R Safinya
- Department of Physics, University of California, Santa Barbara, CA 93106, United States; Department of Materials, University of California, Santa Barbara, CA 93106, United States; Department of Molecular, Cellular, & Developmental Biology, University of California, Santa Barbara, CA 93106, United States.
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Jones MR, Villalón E, Garcia ML. Genetic Manipulation of Neurofilament Protein Phosphorylation. Methods Enzymol 2015; 568:461-76. [PMID: 26795480 DOI: 10.1016/bs.mie.2015.07.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Neurofilament biology is important to understanding structural properties of axons, such as establishment of axonal diameter by radial growth. In order to study the function of neurofilaments, a series of genetically modified mice have been generated. Here, we describe a brief history of genetic modifications used to study neurofilaments, as well as an overview of the steps required to generate a gene-targeted mouse. In addition, we describe steps utilized to analyze neurofilament phosphorylation status using immunoblotting. Taken together, these provide comprehensive analysis of neurofilament function in vivo, which can be applied to many systems.
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Affiliation(s)
- Maria R Jones
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA; C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
| | - Eric Villalón
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA; C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA
| | - Michael L Garcia
- Department of Biological Sciences, University of Missouri, Columbia, Missouri, USA; C.S. Bond Life Sciences Center, University of Missouri, Columbia, Missouri, USA.
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Villalón E, Dale JM, Jones M, Shen H, Garcia ML. Exacerbation of Charcot-Marie-Tooth type 2E neuropathy following traumatic nerve injury. Brain Res 2015; 1627:143-53. [PMID: 26423936 DOI: 10.1016/j.brainres.2015.09.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 08/22/2015] [Accepted: 09/20/2015] [Indexed: 12/21/2022]
Abstract
Charcot-Marie-Tooth disease (CMT) is the most commonly inherited peripheral neuropathy. CMT disease signs include distal limb neuropathy, abnormal gait, sensory defects, and deafness. We generated a novel line of CMT2E mice expressing hNF-L(E397K), which displayed muscle atrophy of the lower limbs without denervation, proximal reduction in large caliber axons, and decreased nerve conduction velocity. In this study, we challenged wild type, hNF-L and hNF-L(E397K) mice with crush injury to the sciatic nerve. We analyzed functional recovery by measuring toe spread and analyzed gait using the Catwalk system. hNF-L(E397K) mice demonstrated reduced recovery from nerve injury consistent with increased susceptibility to neuropathy observed in CMT patients. In addition, hNF-L(E397K) developed a permanent reduction in their ability to weight bear, increased mechanical allodynia, and premature gait shift in the injured limb, which led to increasingly disrupted interlimb coordination in hNF-L(E397K). Exacerbation of neuropathy after injury and identification of gait alterations in combination with previously described pathology suggests that hNF-L(E397K) mice recapitulate many of clinical signs associated with CMT2. Therefore, hNF-L(E397K) mice provide a model for determining the efficacy of novel therapies.
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Affiliation(s)
- Eric Villalón
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA; Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Jeffrey M Dale
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA; Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Maria Jones
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA; Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Hailian Shen
- CurRenji-Medx Clinical Stem Cell Research Center, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China
| | - Michael L Garcia
- Division of Biological Sciences, University of Missouri-Columbia, Columbia, MO 65211, USA; Bond Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA.
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Kornreich M, Malka-Gibor E, Laser-Azogui A, Doron O, Herrmann H, Beck R. Composite bottlebrush mechanics: α-internexin fine-tunes neurofilament network properties. SOFT MATTER 2015; 11:5839-5849. [PMID: 26100609 DOI: 10.1039/c5sm00662g] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Neuronal cytoplasmic intermediate filaments are principal structural and mechanical elements of the axon. Their expression during embryonic development follows a differential pattern, while their unregulated expression is correlated to neurodegenerative diseases. The largest neurofilament proteins of medium (NF-M) and high molecular weight (NF-H) were shown to modulate the axonal architecture and inter-filament spacing. However, the individual roles of the remaining α-internexin (α-Inx) and neurofilament of low molecular weight (NF-L) proteins in composite filaments remained elusive. In contrast to previous predictions, we show that when co-assembled with NF-M, the shortest and the least charged α-Inx protein increases inter-filament spacing. These findings suggest a novel structural explanation for the expression pattern of neurofilament proteins during embryonic development. We explain our results by an analysis of ionic cross-links between the disordered polyampholytic C-terminal tails and suggest that a collapsed conformation of the α-Inx tail domain interferes with tail cross-linking near the filament backbone.
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Affiliation(s)
- M Kornreich
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, 69978 Tel Aviv, Israel.
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41
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Order and disorder in intermediate filament proteins. FEBS Lett 2015; 589:2464-76. [PMID: 26231765 DOI: 10.1016/j.febslet.2015.07.024] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/21/2015] [Accepted: 07/22/2015] [Indexed: 11/20/2022]
Abstract
Intermediate filaments (IFs), important components of the cytoskeleton, provide a versatile, tunable network of self-assembled proteins. IF proteins contain three distinct domains: an α-helical structured rod domain, flanked by intrinsically disordered head and tail domains. Recent studies demonstrated the functional importance of the disordered domains, which differ in length and amino-acid sequence among the 70 different human IF genes. Here, we investigate the biophysical properties of the disordered domains, and review recent findings on the interactions between them. Our analysis highlights key components governing IF functional roles in the cytoskeleton, where the intrinsically disordered domains dictate protein-protein interactions, supramolecular assembly, and macro-scale order.
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Laser-Azogui A, Kornreich M, Malka-Gibor E, Beck R. Neurofilament assembly and function during neuronal development. Curr Opin Cell Biol 2015; 32:92-101. [PMID: 25635910 DOI: 10.1016/j.ceb.2015.01.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 01/06/2015] [Accepted: 01/09/2015] [Indexed: 02/06/2023]
Abstract
Studies on the assembly of neuronal intermediate filaments (IFs) date back to the early work of Alzheimer. Developing neurons express a series of IF proteins, sequentially, at distinct stages of mammalian cell differentiation. This correlates with altered morphologies during the neuronal development, including axon outgrowth, guidance and conductivity. Importantly, neuronal IFs that fail to properly assemble into a filamentous network are a hallmark of neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's, and Parkinson's disease. Traditional structural methodologies fail to fully describe neuronal IF assembly, interactions and resulting function due to IFs structural plasticity, particularly in their C-terminal domains. We review here current progress in the field of neuronal-specific IFs, a dominant component affecting the cytoskeletal structure and function of neurons.
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Affiliation(s)
- Adi Laser-Azogui
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Micha Kornreich
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Eti Malka-Gibor
- Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel
| | - Roy Beck
- The Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978, Israel.
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Gentil BJ, Tibshirani M, Durham HD. Neurofilament dynamics and involvement in neurological disorders. Cell Tissue Res 2015; 360:609-20. [PMID: 25567110 DOI: 10.1007/s00441-014-2082-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 11/19/2014] [Indexed: 12/21/2022]
Abstract
Neurons are extremely polarised cells in which the cytoskeleton, composed of microtubules, microfilaments and neurofilaments, plays a crucial role in maintaining structure and function. Neurofilaments, the 10-nm intermediate filaments of neurons, provide structure and mechanoresistance but also provide a scaffolding for the organization of the nucleus and organelles such as mitochondria and ER. Disruption of neurofilament organization and expression or metabolism of neurofilament proteins is characteristic of certain neurological syndromes including Amyotrophic Lateral Sclerosis, Charcot-Marie-Tooth sensorimotor neuropathies and Giant Axonal Neuropathy. Microfluorometric live imaging techniques have been instrumental in revealing the dynamics of neurofilament assembly and transport and their functions in organizing intracellular organelle networks. The insolubility of neurofilament proteins has limited identifying interactors by conventional biochemical techniques but yeast two-hybrid experiments have revealed new roles for oligomeric, nonfilamentous structures including vesicular trafficking. Although having long half-lives, new evidence points to degradation of subunits by the ubiquitin-proteasome system as a mechanism of normal turnover. Although certain E3-ligases ubiquitinating neurofilament proteins have been identified, the overall process of neurofilament degradation is not well understood. We review these mechanisms of neurofilament homeostasis and abnormalities in motor neuron and peripheral nerve disorders. Much remains to discover about the disruption of processes that leads to their pathological aggregation and accumulation and the relevance to pathogenesis. Understanding these mechanisms is crucial for identifying novel therapeutic strategies.
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Affiliation(s)
- Benoit J Gentil
- Department of Neurology/Neurosurgery and Montreal Neurological Institute, McGill University, Montreal, QC, H3A 2B4, Canada,
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Differential conduction velocity regulation in ipsilateral and contralateral collaterals innervating brainstem coincidence detector neurons. J Neurosci 2014; 34:4914-9. [PMID: 24695710 DOI: 10.1523/jneurosci.5460-13.2014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Information processing in the brain relies on precise timing of signal propagation. The highly conserved neuronal network for computing spatial representations of acoustic signals resolves microsecond timing of sounds processed by the two ears. As such, it provides an excellent model for understanding how precise temporal regulation of neuronal signals is achieved and maintained. The well described avian and mammalian brainstem circuit for computation of interaural time differences is composed of monaural cells in the cochlear nucleus (CN; nucleus magnocellularis in birds) projecting to binaurally innervated coincidence detection neurons in the medial superior olivary nucleus (MSO) in mammals or nucleus laminaris (NL) in birds. Individual axons from CN neurons issue a single axon that bifurcates into an ipsilateral branch and a contralateral branch that innervate segregated dendritic regions of the MSO/NL coincidence detector neurons. We measured conduction velocities of the ipsilateral and contralateral branches of these bifurcating axon collaterals in the chicken by antidromic stimulation of two sites along each branch and whole-cell recordings in the parent neurons. At the end of each experiment, the individual CN neuron and its axon collaterals were filled with dye. We show that the two collaterals of a single axon adjust the conduction velocities individually to achieve the specific conduction velocities essential for precise temporal integration of information from the two ears, as required for sound localization. More generally, these results suggest that individual axonal segments in the CNS interact locally with surrounding neural structures to determine conduction velocity.
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45
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Paus T, Pesaresi M, French L. White matter as a transport system. Neuroscience 2014; 276:117-25. [PMID: 24508743 DOI: 10.1016/j.neuroscience.2014.01.055] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/14/2014] [Accepted: 01/29/2014] [Indexed: 12/14/2022]
Abstract
There are two ways to picture white matter: as a grid of electrical wires or a network of roads. The first metaphor captures the classical function of an axon as conductor of action potentials (and information) from one brain region to another. The second one points to the important role of axons in a bi-directional transport of biological molecules and organelles between the cell body and synapse. Given the wide variety of such cargoes, a well-functioning axonal transport is critical for a number of processes, including neurotransmission, metabolism and viability of neurons. This selective review will emphasize the need for considering axonal transport when interpreting functional consequences of inter-individual variations in the structural properties of white matter. We start by describing the space occupied by white matter and techniques used in vivo for its characterization. We then provide examples of key features of maturation and aging of white matter, as well as some of the common abnormalities observed in neurodevelopmental and neurodegenerative disorders. Next, we review work that motivated our focus on axonal diameter, and explain the relationships between transport and cytoskeleton within the axon. We will conclude by describing molecular machinery of axonal transport and genes that may contribute to inter-individual variations in axonal diameter and axonal transport.
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Affiliation(s)
- T Paus
- Rotman Research Institute, University of Toronto, Toronto, Canada.
| | - M Pesaresi
- Rotman Research Institute, University of Toronto, Toronto, Canada
| | - L French
- Rotman Research Institute, University of Toronto, Toronto, Canada
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46
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Pajevic S, Basser PJ, Fields RD. Role of myelin plasticity in oscillations and synchrony of neuronal activity. Neuroscience 2013; 276:135-47. [PMID: 24291730 DOI: 10.1016/j.neuroscience.2013.11.007] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 10/07/2013] [Accepted: 11/04/2013] [Indexed: 01/25/2023]
Abstract
Conduction time is typically ignored in computational models of neural network function. Here we consider the effects of conduction delays on the synchrony of neuronal activity and neural oscillators, and evaluate the consequences of allowing conduction velocity (CV) to be regulated adaptively. We propose that CV variation, mediated by myelin, could provide an important mechanism of activity-dependent nervous system plasticity. Even small changes in CV, resulting from small changes in myelin thickness or nodal structure, could have profound effects on neuronal network function in terms of spike-time arrival, oscillation frequency, oscillator coupling, and propagation of brain waves. For example, a conduction delay of 5ms could change interactions of two coupled oscillators at the upper end of the gamma frequency range (∼100Hz) from constructive to destructive interference; delays smaller than 1ms could change the phase by 30°, significantly affecting signal amplitude. Myelin plasticity, as another form of activity-dependent plasticity, is relevant not only to nervous system development but also to complex information processing tasks that involve coupling and synchrony among different brain rhythms. We use coupled oscillator models with time delays to explore the importance of adaptive time delays and adaptive synaptic strengths. The impairment of activity-dependent myelination and the loss of adaptive time delays may contribute to disorders where hyper- and hypo-synchrony of neuronal firing leads to dysfunction (e.g., dyslexia, schizophrenia, epilepsy).
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Affiliation(s)
- S Pajevic
- Mathematical and Statistical Computing Laboratory, Division of Computational Bioscience, Center for Information Technology, NIH, USA
| | - P J Basser
- Section on Tissue Biophysics and Biomimetics, Program on Pediatric Imaging and Tissue Sciences, NICHD, USA
| | - R D Fields
- Nervous System Development and Plasticity Section, National Institute of Child Health and Human Development, NIH, USA.
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Florath I, Butterbach K, Müller H, Bewerunge-Hudler M, Brenner H. Cross-sectional and longitudinal changes in DNA methylation with age: an epigenome-wide analysis revealing over 60 novel age-associated CpG sites. Hum Mol Genet 2013; 23:1186-201. [PMID: 24163245 DOI: 10.1093/hmg/ddt531] [Citation(s) in RCA: 231] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Understanding the role of epigenetic modifications, e.g. DNA methylation, in the process of aging requires the characterization of methylation patterns in large cohorts. We analysed >480 000 CpG sites using Infinium HumanMethylation450 BeadChip (Illumina) in whole blood DNA of 965 participants of a population-based cohort study aged between 50 and 75 years. In an exploratory analysis in 400 individuals, 200 CpG sites with the highest Spearman correlation coefficients for the association between methylation and age were identified. Of these 200 CpGs, 162 were significantly associated with age, which was verified in an independent cohort of 498 individuals using mixed linear regression models adjusted for gender, smoking behaviour, age-related diseases and random batch effect and corrected for multiple testing by Bonferroni. In another independent cohort of 67 individuals without history of major age-related diseases and with a follow-up of 8 years, we observed a gain in methylation at 96% (52%, significant) of the positively age-associated CpGs and a loss at all (89%, significant) of the negatively age-associated CpGs in each individual while getting 8 years older. A regression model for age prediction based on 17 CpGs as predicting variables explained 71% of the variance in age with an average accuracy of 2.6 years. In comparison with cord blood samples obtained from the Ulm Birth Cohort Study, we observed a more than 2-fold change in mean methylation levels from birth to older age at 86 CpGs. We were able to identify 65 novel CpG sites with significant association of methylation with age.
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Affiliation(s)
- Ines Florath
- Division of Clinical Epidemiology and Aging Research, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany
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Mychasiuk R, Muhammad A, Ilnytskyy S, Kolb B. Persistent gene expression changes in NAc, mPFC, and OFC associated with previous nicotine or amphetamine exposure. Behav Brain Res 2013; 256:655-61. [PMID: 24021241 DOI: 10.1016/j.bbr.2013.09.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Accepted: 09/01/2013] [Indexed: 01/03/2023]
Abstract
Highly addictive drugs like nicotine and amphetamine not only change an individual's behaviour in the short and long-term, they also induce persistent changes in neuronal excitability and morphology. Although research has started to examine the epigenetic changes that occur immediately after drug exposure, there has been little investigation into the persistent modifications to the epigenome that likely moderate the stable maintenance of the neurological changes. Male Long-Evans rats were administered amphetamine, nicotine, or saline for 14 consecutive days, given a 14 day withdrawal period, and then sacrificed. DNA from the mPFC, OFC, and nucleus accumbens (NAc) was used for global DNA methylation analysis and RNA from the same brain regions was used for gene expression analysis. Following the two-week withdrawal period, exposure to amphetamine or nicotine was associated with a decrease in global DNA methylation in each brain region examined. Previous exposure to nicotine was associated with changes in expression of 16 genes (NAc:6, mPFC:5, OFC:5) whereas exposure to amphetamine was associated with changes in expression of 25 genes (NAc:13, OFC:8, mPFC:4). The persistent epigenetic changes associated with exposure to amphetamine and nicotine were region and drug dependent, and differ from the latent epigenetic changes that occur immediately after drug exposure. The changes in DNA methylation are consistent with the gene expression results and provide further support to the notion that DNA methylation is the key regulatory mechanism for experience dependent changes.
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Affiliation(s)
- Richelle Mychasiuk
- Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Canada.
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Eftekhari S, Warfvinge K, Blixt FW, Edvinsson L. Differentiation of nerve fibers storing CGRP and CGRP receptors in the peripheral trigeminovascular system. THE JOURNAL OF PAIN 2013; 14:1289-303. [PMID: 23958278 DOI: 10.1016/j.jpain.2013.03.010] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 02/26/2013] [Accepted: 03/20/2013] [Indexed: 11/29/2022]
Abstract
UNLABELLED Primary headaches such as migraine are postulated to involve the activation of sensory trigeminal pain neurons that innervate intracranial blood vessels and the dura mater. It is suggested that local activation of these sensory nerves may involve dural mast cells as one factor in local inflammation, causing sensitization of meningeal nociceptors. Immunofluorescence was used to study the detailed distribution of calcitonin gene-related peptide (CGRP) and its receptor components calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein 1 (RAMP1) in whole-mount rat dura mater and in human dural vessels. The relative distributions of CGRP, CLR, and RAMP1 were evaluated with respect to each other and in relationship to mast cells, myelin, substance P, neuronal nitric oxide synthase, pituitary adenylate cyclase-activating polypeptide, and vasoactive intestinal peptide. CGRP expression was found in thin unmyelinated fibers, whereas CLR and RAMP1 were expressed in thicker myelinated fibers coexpressed with an A-fiber marker. CLR and RAMP1 immunoreactivity colocalized with mast cell tryptase in rodent; however, expression of both receptor components was not observed in human mast cells. Immunoreactive substance P fibers coexpressed CGRP, although neuronal nitric oxide synthase and vasoactive intestinal peptide expression was very limited, and these fibers were distinct from the CGRP-positive fibers. Few pituitary adenylate cyclase-activating polypeptide immunoreactive fibers occurred and some colocalized with CGRP. PERSPECTIVE This study demonstrates the detailed distribution of CGRP and its receptor in the dura mater. These data suggest that CGRP is expressed in C-fibers and may act on A-fibers, rodent mast cells, and vascular smooth muscle cells that express the CGRP receptor. These sites represent potential pathophysiological targets of novel antimigraine agents such as the newly developed CGRP receptor antagonists.
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Affiliation(s)
- Sajedeh Eftekhari
- Department of Clinical Sciences, Division of Experimental Vascular Research, Lund University, Lund, Sweden.
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50
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Seidl AH. Regulation of conduction time along axons. Neuroscience 2013; 276:126-34. [PMID: 23820043 DOI: 10.1016/j.neuroscience.2013.06.047] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/13/2013] [Accepted: 06/17/2013] [Indexed: 11/17/2022]
Abstract
Timely delivery of information is essential for proper functioning of the nervous system. Precise regulation of nerve conduction velocity is needed for correct exertion of motor skills, sensory integration and cognitive functions. In vertebrates, the rapid transmission of signals along nerve fibers is made possible by the myelination of axons and the resulting saltatory conduction in between nodes of Ranvier. Myelin is a specialization of glia cells and is provided by oligodendrocytes in the central nervous system. Myelination not only maximizes conduction velocity, but also provides a means to systematically regulate conduction times in the nervous system. Systematic regulation of conduction velocity along axons, and thus systematic regulation of conduction time in between neural areas, is a common occurrence in the nervous system. To date, little is understood about the mechanism that underlies systematic conduction velocity regulation and conduction time synchrony. Node assembly, internode distance (node spacing) and axon diameter - all parameters determining the speed of signal propagation along axons - are controlled by myelinating glia. Therefore, an interaction between glial cells and neurons has been suggested. This review summarizes examples of neural systems in which conduction velocity is regulated by anatomical variations along axons. While functional implications in these systems are not always clear, recent studies on the auditory system of birds and mammals present examples of conduction velocity regulation in systems with high temporal precision and a defined biological function. Together these findings suggest an active process that shapes the interaction between axons and myelinating glia to control conduction velocity along axons. Future studies involving these systems may provide further insight into how specific conduction times in the brain are established and maintained in development. Throughout the text, conduction velocity is used for the speed of signal propagation, i.e. the speed at which an action potential travels. Conduction time refers to the time it takes for a specific signal to travel from its origin to its target, i.e. neuronal cell body to axonal terminal.
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Affiliation(s)
- A H Seidl
- Virginia Merrill Bloedel Hearing Research Center, University of Washington, Seattle, WA, USA; Department of Otolaryngology - Head & Neck Surgery, University of Washington, Seattle, WA, USA.
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