1
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Reyes-Ábalos AL, Álvarez-Zabaleta M, Olivera-Bravo S, Di Tomaso MV. Astrocyte DNA damage and response upon acute exposure to ethanol and corticosterone. FRONTIERS IN TOXICOLOGY 2024; 5:1277047. [PMID: 38259729 PMCID: PMC10800529 DOI: 10.3389/ftox.2023.1277047] [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: 08/13/2023] [Accepted: 12/11/2023] [Indexed: 01/24/2024] Open
Abstract
Introduction: Astrocytes are the glial cells responsible for brain homeostasis, but if injured, they could damage neural cells even deadly. Genetic damage, DNA damage response (DDR), and its downstream cascades are dramatic events poorly studied in astrocytes. Hypothesis and methods: We propose that 1 h of 400 mmol/L ethanol and/or 1 μmol/L corticosterone exposure of cultured hippocampal astrocytes damages DNA, activating the DDR and eliciting functional changes. Immunolabeling against γH2AX (chromatin DNA damage sites), cyclin D1 (cell cycle control), nuclear (base excision repair, BER), and cytoplasmic (anti-inflammatory functions) APE1, ribosomal nucleolus proteins together with GFAP and S100β plus scanning electron microscopy studies of the astrocyte surface were carried out. Results: Data obtained indicate significant DNA damage, immediate cell cycle arrest, and BER activation. Changes in the cytoplasmic signals of cyclin D1 and APE1, nucleolus number, and membrane-attached vesicles strongly suggest a reactivity like astrocyte response without significant morphological changes. Discussion: Obtained results uncover astrocyte genome immediate vulnerability and DDR activation, plus a functional response that might in part, be signaled through extracellular vesicles, evidencing the complex influence that astrocytes may have on the CNS even upon short-term aggressions.
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Affiliation(s)
- Ana Laura Reyes-Ábalos
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Magdalena Álvarez-Zabaleta
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | | | - María Vittoria Di Tomaso
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
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2
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Krishnan A, Verge VMK, Zochodne DW. Hallmarks of peripheral nerve injury and regeneration. HANDBOOK OF CLINICAL NEUROLOGY 2024; 201:1-17. [PMID: 38697733 DOI: 10.1016/b978-0-323-90108-6.00014-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2024]
Abstract
Peripheral nerves are functional networks in the body. Disruption of these networks induces varied functional consequences depending on the types of nerves and organs affected. Despite the advances in microsurgical repair and understanding of nerve regeneration biology, restoring full functions after severe traumatic nerve injuries is still far from achieved. While a blunted growth response from axons and errors in axon guidance due to physical barriers may surface as the major hurdles in repairing nerves, critical additional cellular and molecular aspects challenge the orderly healing of injured nerves. Understanding the systematic reprogramming of injured nerves at the cellular and molecular levels, referred to here as "hallmarks of nerve injury regeneration," will offer better ideas. This chapter discusses the hallmarks of nerve injury and regeneration and critical points of failures in the natural healing process. Potential pharmacological and nonpharmacological intervention points for repairing nerves are also discussed.
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Affiliation(s)
- Anand Krishnan
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada; Cameco MS Neuroscience Research Centre (CMSNRC), Saskatoon, SK, Canada.
| | - Valerie M K Verge
- Department of Anatomy, Physiology, and Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada; Cameco MS Neuroscience Research Centre (CMSNRC), Saskatoon, SK, Canada.
| | - Douglas W Zochodne
- Neuroscience and Mental Health Institute and Division of Neurology, Department of Medicine, University of Alberta, Edmonton, AB, Canada.
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3
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Mitchell ME, Cook LC, Shiers S, Tavares-Ferreira D, Akopian AN, Dussor G, Price TJ. Characterization of Fragile X Mental Retardation Protein expression in human nociceptors and their axonal projections to the spinal dorsal horn. J Comp Neurol 2023; 531:814-835. [PMID: 36808110 PMCID: PMC10038933 DOI: 10.1002/cne.25463] [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: 09/19/2022] [Revised: 12/20/2022] [Accepted: 01/27/2023] [Indexed: 02/23/2023]
Abstract
Fragile X Mental Retardation Protein (FMRP) regulates activity-dependent RNA localization and local translation to modulate synaptic plasticity throughout the central nervous system. Mutations in the FMR1 gene that hinder or ablate FMRP function cause Fragile X Syndrome (FXS), a disorder associated with sensory processing dysfunction. FXS premutations are associated with increased FMRP expression and neurological impairments including sex dimorphic presentations of chronic pain. In mice, FMRP ablation causes dysregulated dorsal root ganglion (DRG) neuron excitability and synaptic vesicle exocytosis, spinal circuit activity, and decreased translation-dependent nociceptive sensitization. Activity-dependent, local translation is a key mechanism for enhancing primary nociceptor excitability that promotes pain in animals and humans. These works indicate that FMRP likely regulates nociception and pain at the level of the primary nociceptor or spinal cord. Therefore, we sought to better understand FMRP expression in the human DRG and spinal cord using immunostaining in organ donor tissues. We find that FMRP is highly expressed in DRG and spinal neuron subsets with substantia gelatinosa exhibiting the most abundant immunoreactivity in spinal synaptic fields. Here, it is expressed in nociceptor axons. FMRP puncta colocalized with Nav1.7 and TRPV1 receptor signals suggesting a pool of axoplasmic FMRP localizes to plasma membrane-associated loci in these branches. Interestingly, FMRP puncta exhibited notable colocalization with calcitonin gene-related peptide (CGRP) immunoreactivity selectively in female spinal cord. Our results support a regulatory role for FMRP in human nociceptor axons of the dorsal horn and implicate it in the sex dimorphic actions of CGRP signaling in nociceptive sensitization and chronic pain.
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Affiliation(s)
- Molly E Mitchell
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Lauren C Cook
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Stephanie Shiers
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Diana Tavares-Ferreira
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Armen N Akopian
- Department of Endodontics, UT Health San Antonio, San Antonio, Texas, USA
| | - Gregory Dussor
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, USA
| | - Theodore J Price
- Center for Advanced Pain Studies, School of Behavioral and Brain Sciences, University of Texas at Dallas, Richardson, Texas, USA
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4
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Koppers M, Holt CE. Receptor-Ribosome Coupling: A Link Between Extrinsic Signals and mRNA Translation in Neuronal Compartments. Annu Rev Neurosci 2022; 45:41-61. [DOI: 10.1146/annurev-neuro-083021-110015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Axons receive extracellular signals that help to guide growth and synapse formation during development and to maintain neuronal function and survival during maturity. These signals relay information via cell surface receptors that can initiate local intracellular signaling at the site of binding, including local messenger RNA (mRNA) translation. Direct coupling of translational machinery to receptors provides an attractive way to activate this local mRNA translation and change the local proteome with high spatiotemporal resolution. Here, we first discuss the increasing evidence that different external stimuli trigger translation of specific subsets of mRNAs in axons via receptors and thus play a prominent role in various processes in both developing and mature neurons. We then discuss the receptor-mediated molecular mechanisms that regulate local mRNA translational with a focus on direct receptor-ribosome coupling. We advance the idea that receptor-ribosome coupling provides several advantages over other translational regulation mechanisms and is a common mechanism in cell communication. Expected final online publication date for the Annual Review of Neuroscience, Volume 45 is July 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Max Koppers
- Department of Biology, Division of Cell Biology, Neurobiology and Biophysics, Utrecht University, Utrecht, The Netherlands
| | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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5
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Di Paolo A, Farias J, Garat J, Macklin A, Ignatchenko V, Kislinger T, Sotelo Silveira J. Rat Sciatic Nerve Axoplasm Proteome Is Enriched with Ribosomal Proteins during Regeneration Processes. J Proteome Res 2021; 20:2506-2520. [PMID: 33793244 DOI: 10.1021/acs.jproteome.0c00980] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Axons are complex subcellular compartments that are extremely long in relation to cell bodies, especially in peripheral nerves. Many processes are required and regulated during axon injury, including anterograde and retrograde transport, glia-to-axon macromolecular transfer, and local axonal protein synthesis. Many in vitro omics approaches have been used to gain insight into these processes, but few have been applied in vivo. Here we adapted the osmotic ex vivo axoplasm isolation method and analyzed the adult rat sciatic-nerve-extruded axoplasm by label-free quantitative proteomics before and after injury. 2087 proteins groups were detected in the axoplasm, revealing translation machinery and microtubule-associated proteins as the most overrepresented biological processes. Ribosomal proteins (73) were detected in the uninjured axoplasm and increased their levels after injury but not within whole sciatic nerves. Meta-analysis showed that detected ribosomal proteins were present in in vitro axonal proteomes. Because local protein synthesis is important for protein localization, we were interested in detecting the most abundant newly synthesized axonal proteins in vivo. With an MS/MS-BONCAT approach, we detected 42 newly synthesized protein groups. Overall, our work indicates that proteomics profiling is useful for local axonal interrogation and suggests that ribosomal proteins may play an important role, especially during injury.
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Affiliation(s)
- Andres Di Paolo
- Departamento de Proteínas y Ácidos Nucleicos, IIBCE, 11600 Montevideo, Uruguay.,Departamento de Genómica, IIBCE, 11600 Montevideo, Uruguay
| | | | - Joaquin Garat
- Departamento de Genómica, IIBCE, 11600 Montevideo, Uruguay
| | - Andrew Macklin
- Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Vladimir Ignatchenko
- Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - Thomas Kislinger
- Princess Margaret Cancer Centre, 101 College Street, Toronto, Ontario M5G 1L7, Canada.,Department of Medical Biophysics, University of Toronto, 101 College Street, Toronto, Ontario M5G 1L7, Canada
| | - José Sotelo Silveira
- Departamento de Genómica, IIBCE, 11600 Montevideo, Uruguay.,Departamento de Biología Celular y Molecular, Facultad de Ciencias, 11400 Montevideo, Uruguay
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6
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Costa RO, Martins H, Martins LF, Cwetsch AW, Mele M, Pedro JR, Tomé D, Jeon NL, Cancedda L, Jaffrey SR, Almeida RD. Synaptogenesis Stimulates a Proteasome-Mediated Ribosome Reduction in Axons. Cell Rep 2020; 28:864-876.e6. [PMID: 31340150 PMCID: PMC6686882 DOI: 10.1016/j.celrep.2019.06.080] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 12/21/2018] [Accepted: 06/21/2019] [Indexed: 11/19/2022] Open
Abstract
Ribosomes and a subset of cellular mRNAs are trafficked into axons of developing neurons. The axonal localization of translational machinery allows new proteins to be rapidly and locally synthesized during axonal growth and pathfinding. However, in mature neurons, axonal ribosomes are significantly reduced or even absent. The mechanism that elicits this removal is currently unknown. Here, we demonstrate that synapse formation is the trigger for ribosome reduction in mature axons. In vivo analysis shows that axonal ribosome levels decrease in rat brain at a developmental stage coincident with synapse formation. Next, we observe in vitro that different synaptogenic inducers trigger an overall decrease of ribosomal proteins and rRNA in the axons of spinal motor neurons. We further observe that this process is dependent on the ubiquitin-proteasome system but not on autophagy. Together, these data identify synaptogenesis as the long missing biological trigger that leads to ribosome disappearance during axonal maturation. The mechanism behind the striking loss of ribosomes from axons during neuronal maturation is unknown. Using in vivo and in vitro models, including neuron-muscle co-cultures and combining biochemistry and imaging techniques, Costa et al. demonstrate that synapse formation triggers ribosome reduction by a mechanism involving the ubiquitin-proteasome system.
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Affiliation(s)
- Rui O Costa
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal.
| | - Helena Martins
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Luís F Martins
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal; PhD Programme in Experimental Biology and Biomedicine (PDBEB), Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Andrzej W Cwetsch
- NBT - Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genoa, Italy
| | - Miranda Mele
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal
| | - Joana R Pedro
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal
| | - Diogo Tomé
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Noo Li Jeon
- Institute of Advanced Machinery and Design, Seoul National University, Seoul, Republic of Korea; Department of Mechanical and Aerospace Engineering, Seoul National University, Seoul, Republic of Korea
| | - Laura Cancedda
- NBT - Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genoa, Italy; Dulbecco Telethon Institute, Roma, Italy
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Ramiro D Almeida
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Institute for Interdisciplinary Research, University of Coimbra, Coimbra, Portugal; iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal.
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7
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Farias J, Holt CE, Sotelo JR, Sotelo-Silveira JR. Axon microdissection and transcriptome profiling reveals the in vivo RNA content of fully differentiated myelinated motor axons. RNA (NEW YORK, N.Y.) 2020; 26:595-612. [PMID: 32051223 PMCID: PMC7161357 DOI: 10.1261/rna.073700.119] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/31/2020] [Indexed: 05/23/2023]
Abstract
Axonal protein synthesis has been shown to play a role in developmental and regenerative growth, as well as in the maintenance of the axoplasm in a steady state. Recent studies have begun to identify the mRNAs localized in axons, which could be translated locally under different conditions. Despite that by now hundreds or thousands of mRNAs have been shown to be localized into the axonal compartment of cultured neurons in vitro, knowledge of which mRNAs are localized in mature myelinated axons is quite limited. With the purpose of characterizing the transcriptome of mature myelinated motor axons of peripheral nervous systems, we modified the axon microdissection method devised by Koenig, enabling the isolation of the axoplasm RNA to perform RNA-seq analysis. The transcriptome analysis indicates that the number of RNAs detected in mature axons is lower in comparison with in vitro data, depleted of glial markers, and enriched in neuronal markers. The mature myelinated axons are enriched for mRNAs related to cytoskeleton, translation, and oxidative phosphorylation. Moreover, it was possible to define core genes present in axons when comparing our data with transcriptomic data of axons grown in different conditions. This work provides evidence that axon microdissection is a valuable method to obtain genome-wide data from mature and myelinated axons of the peripheral nervous system, and could be especially useful for the study of axonal involvement in neurodegenerative pathologies of motor neurons such as amyotrophic lateral sclerosis (ALS) and spinal muscular atrophies (SMA).
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Affiliation(s)
- Joaquina Farias
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, 11600, Uruguay
- Departamento de Proteínas y Ácidos Nucléicos, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, 11600, Uruguay
| | - Christine E Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3DY, United Kingdom
| | - José R Sotelo
- Departamento de Proteínas y Ácidos Nucléicos, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, 11600, Uruguay
| | - José R Sotelo-Silveira
- Departamento de Genómica, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, 11600, Uruguay
- Departamento de Biología Celular y Molecular, Facultad de Ciencias, Universidad de la República, Montevideo, 11400, Uruguay
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8
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Farias J, Sotelo JR, Sotelo‐Silveira J. Toward Axonal System Biology: Genome Wide Views of Local mRNA Translation. Proteomics 2019; 19:e1900054. [DOI: 10.1002/pmic.201900054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 04/12/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Joaquina Farias
- Departamento de Proteínas y Ácidos NucleicosInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
- Departamento de GenómicaInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
| | - José Roberto Sotelo
- Departamento de Proteínas y Ácidos NucleicosInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
| | - José Sotelo‐Silveira
- Departamento de GenómicaInstituto de Investigaciones Biológicas Clemente Estable Montevideo CP 11600 Uruguay
- Sección Biología CelularFacultad de Ciencias, Universidad de la República Montevideo CP 11400 Uruguay
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9
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Abstract
Toxic peripheral neuropathies are an important form of acquired polyneuropathy produced by a variety of xenobiotics and different exposure scenarios. Delineating the mechanisms of neurotoxicants and determining the degenerative biological pathways triggered by peripheral neurotoxicants will facilitate the development of sensitive and specific biochemical-based methods for identifying neurotoxicants, designing therapeutic interventions, and developing structure-activity relationships for predicting potential neurotoxicants. This review presents an overview of the general concepts of toxic peripheral neuropathies with the goal of providing insight into why certain agents target the peripheral nervous system and produce their associated lesions. Experimental data and the main hypotheses for the mechanisms of selected agents that produce neuronopathies, axonopathies, or myelinopathies including covalent or noncovalent modifications, compromised energy or protein biosynthesis, and oxidative injury and disruption of ionic gradients across membranes are presented. The relevance of signaling between the main components of peripheral nerve, that is, glia, neuronal perikaryon, and axon, as a target for neurotoxicants and the contribution of active programmed degenerative pathways to the lesions observed in toxic peripheral neuropathies is also discussed.
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10
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Koley S, Rozenbaum M, Fainzilber M, Terenzio M. Translating regeneration: Local protein synthesis in the neuronal injury response. Neurosci Res 2019; 139:26-36. [DOI: 10.1016/j.neures.2018.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 09/13/2018] [Accepted: 10/02/2018] [Indexed: 12/21/2022]
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11
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Negro S, Stazi M, Marchioretto M, Tebaldi T, Rodella U, Duregotti E, Gerke V, Quattrone A, Montecucco C, Rigoni M, Viero G. Hydrogen peroxide is a neuronal alarmin that triggers specific RNAs, local translation of Annexin A2, and cytoskeletal remodeling in Schwann cells. RNA (NEW YORK, N.Y.) 2018; 24:915-925. [PMID: 29643068 PMCID: PMC6004060 DOI: 10.1261/rna.064816.117] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 03/26/2018] [Indexed: 06/08/2023]
Abstract
Schwann cells are key players in neuro-regeneration: They sense "alarm" signals released by degenerating nerve terminals and differentiate toward a proregenerative phenotype, with phagocytosis of nerve debris and nerve guidance. At the murine neuromuscular junction, hydrogen peroxide (H2O2) is a key signal of Schwann cells' activation in response to a variety of nerve injuries. Here we report that Schwann cells exposed to low doses of H2O2 rewire the expression of several RNAs at both transcriptional and translational levels. Among the genes positively regulated at both levels, we identified an enriched cluster involved in cytoskeleton remodeling and cell migration, with the Annexin (Anxa) proteins being the most represented family. We show that both Annexin A2 (Anxa2) transcript and protein accumulate at the tips of long pseudopods that Schwann cells extend upon H2O2 exposure. Interestingly, Schwann cells reply to this signal and to nerve injury by locally translating Anxa2 in pseudopods, and undergo an extensive cytoskeleton remodeling. Our results show that, similarly to neurons, Schwann cells take advantage of local protein synthesis to change shape and move toward damaged axonal terminals to facilitate axonal regeneration.
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Affiliation(s)
- Samuele Negro
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Marco Stazi
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | | | - Toma Tebaldi
- Centre for Integrative Biology, University of Trento, 38123 Povo, Italy
| | - Umberto Rodella
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Elisa Duregotti
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Volker Gerke
- Institute of Medical Biochemistry, University of Münster, 48149 Münster, Germany
| | | | - Cesare Montecucco
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
- CNR Institute of Neuroscience, 35131 Padua, Italy
| | - Michela Rigoni
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Gabriella Viero
- Institute of Biophysics, CNR Unit at Trento, 38123 Povo, Italy
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12
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Luarte A, Cornejo VH, Bertin F, Gallardo J, Couve A. The axonal endoplasmic reticulum: One organelle-many functions in development, maintenance, and plasticity. Dev Neurobiol 2017; 78:181-208. [PMID: 29134778 DOI: 10.1002/dneu.22560] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/02/2017] [Accepted: 11/07/2017] [Indexed: 12/11/2022]
Abstract
The endoplasmic reticulum (ER) is highly conserved in eukaryotes and neurons. Indeed, the localization of the organelle in axons has been known for nearly half a century. However, the relevance of the axonal ER is only beginning to emerge. In this review, we discuss the structure of the ER in axons, examining the role of ER-shaping proteins and highlighting reticulons. We analyze the multiple functions of the ER and their potential contribution to axonal physiology. First, we examine the emerging roles of the axonal ER in lipid synthesis, protein translation, processing, quality control, and secretory trafficking of transmembrane proteins. We also review the impact of the ER on calcium dynamics, focusing on intracellular mechanisms and functions. We describe the interactions between the ER and endosomes, mitochondria, and synaptic vesicles. Finally, we analyze available proteomic data of axonal preparations to reveal the dynamic functionality of the ER in axons during development. We suggest that the dynamic proteome and a validated axonal interactome, together with state-of-the-art methodologies, may provide interesting research avenues in axon physiology that may extend to pathology and regeneration. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 181-208, 2018.
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Affiliation(s)
- Alejandro Luarte
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Víctor Hugo Cornejo
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Francisca Bertin
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Javiera Gallardo
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Andrés Couve
- Department of Neuroscience, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Faculty of Medicine, Universidad de Chile, Santiago, Chile
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13
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Rangaraju V, Tom Dieck S, Schuman EM. Local translation in neuronal compartments: how local is local? EMBO Rep 2017; 18:693-711. [PMID: 28404606 DOI: 10.15252/embr.201744045] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/15/2017] [Accepted: 03/15/2017] [Indexed: 12/18/2022] Open
Abstract
Efficient neuronal function depends on the continued modulation of the local neuronal proteome. Local protein synthesis plays a central role in tuning the neuronal proteome at specific neuronal regions. Various aspects of translation such as the localization of translational machinery, spatial spread of the newly translated proteins, and their site of action are carried out in specialized neuronal subcompartments to result in a localized functional outcome. In this review, we focus on the various aspects of these local translation compartments such as size, biochemical and organelle composition, structural boundaries, and temporal dynamics. We also discuss the apparent absence of definitive components of translation in these local compartments and the emerging state-of-the-art tools that could help dissecting these conundrums in greater detail in the future.
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Affiliation(s)
- Vidhya Rangaraju
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
| | | | - Erin M Schuman
- Max Planck Institute for Brain Research, Frankfurt am Main, Germany
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14
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Cornejo VH, Luarte A, Couve A. Global and local mechanisms sustain axonal proteostasis of transmembrane proteins. Traffic 2017; 18:255-266. [PMID: 28220989 DOI: 10.1111/tra.12472] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/02/2017] [Accepted: 02/16/2017] [Indexed: 12/22/2022]
Abstract
The control of neuronal protein homeostasis or proteostasis is tightly regulated both spatially and temporally, assuring accurate and integrated responses to external or intrinsic stimuli. Local or autonomous responses in dendritic and axonal compartments are crucial to sustain function during development, physiology and in response to damage or disease. Axons are responsible for generating and propagating electrical impulses in neurons, and the establishment and maintenance of their molecular composition are subject to extreme constraints exerted by length and size. Proteins that require the secretory pathway, such as receptors, transporters, ion channels or cell adhesion molecules, are fundamental for axonal function, but whether axons regulate their abundance autonomously and how they achieve this is not clear. Evidence supports the role of three complementary mechanisms to maintain proteostasis of these axonal proteins, namely vesicular transport, local translation and trafficking and transfer from supporting cells. Here, we review these mechanisms, their molecular machineries and contribution to neuronal function. We also examine the signaling pathways involved in local translation and their role during development and nerve injury. We discuss the relative contributions of a transport-controlled proteome directed by the soma (global regulation) versus a local-controlled proteome based on local translation or cell transfer (local regulation).
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Affiliation(s)
- Víctor Hugo Cornejo
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
| | - Alejandro Luarte
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
| | - Andrés Couve
- Program of Physiology and Biophysics, ICBM, Faculty of Medicine, Universidad de Chile, Santiago, Chile.,Biomedical Neuroscience Institute, Universidad de Chile, Santiago, Chile
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15
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Dynamic Axonal Translation in Developing and Mature Visual Circuits. Cell 2016; 166:181-92. [PMID: 27321671 PMCID: PMC4930487 DOI: 10.1016/j.cell.2016.05.029] [Citation(s) in RCA: 305] [Impact Index Per Article: 38.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 03/09/2016] [Accepted: 05/04/2016] [Indexed: 01/06/2023]
Abstract
Local mRNA translation mediates the adaptive responses of axons to extrinsic signals, but direct evidence that it occurs in mammalian CNS axons in vivo is scant. We developed an axon-TRAP-RiboTag approach in mouse that allows deep-sequencing analysis of ribosome-bound mRNAs in the retinal ganglion cell axons of the developing and adult retinotectal projection in vivo. The embryonic-to-postnatal axonal translatome comprises an evolving subset of enriched genes with axon-specific roles, suggesting distinct steps in axon wiring, such as elongation, pruning, and synaptogenesis. Adult axons, remarkably, have a complex translatome with strong links to axon survival, neurotransmission, and neurodegenerative disease. Translationally co-regulated mRNA subsets share common upstream regulators, and sequence elements generated by alternative splicing promote axonal mRNA translation. Our results indicate that intricate regulation of compartment-specific mRNA translation in mammalian CNS axons supports the formation and maintenance of neural circuits in vivo. Dynamic translatome of retinal axons in vivo matches changing subcellular function Adult CNS axons translate mRNAs for synaptic transmission and axon survival in vivo Target mRNAs of key translation regulators show developmental co-regulation Axon-specific sequence motifs link alternative splicing to axonal translation
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16
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Jin LQ, Pennise CR, Rodemer W, Jahn KS, Selzer ME. Protein synthetic machinery and mRNA in regenerating tips of spinal cord axons in lamprey. J Comp Neurol 2016; 524:3614-3640. [PMID: 27120118 DOI: 10.1002/cne.24020] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 02/03/2023]
Abstract
Polyribosomes, mRNA, and other elements of translational machinery have been reported in peripheral nerves and in elongating injured axons of sensory neurons in vitro, primarily in growth cones. Evidence for involvement of local protein synthesis in regenerating central nervous system (CNS) axons is less extensive. We monitored regeneration of back-labeled lamprey spinal axons after spinal cord transection and detected mRNA in axon tips by in situ hybridization and microaspiration of their axoplasm. Poly(A)+mRNA was present in the axon tips, and was more abundant in actively regenerating tips than in static or retracting ones. Target-specific polymerase chain reaction (PCR) and in situ hybridization revealed plentiful mRNA for the low molecular neurofilament subunit and β-tubulin, but very little for β-actin, consistent with the morphology of their tips, which lack filopodia and lamellipodia. Electron microscopy showed ribosomes/polyribosomes in the distal parts of axon tips and in association with vesicle-like membranes, primarily in the tip. In one instance, there were structures with the appearance of rough endoplasmic reticulum. Immunohistochemistry showed patches of ribosomal protein S6 positivity in a similar distribution. The results suggest that local protein synthesis might be involved in the mechanism of axon regeneration in the lamprey spinal cord. J. Comp. Neurol. 524:3614-3640, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Li-Qing Jin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140.
| | - Cynthia R Pennise
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140
| | - William Rodemer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140
| | - Kristen S Jahn
- The Children's Hospital of Philadelphia, 1108 Pine Street, Philadelphia, PA, 19107
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140. .,Department of Neurology, Lewis Katz School of Medicine at Temple University, 3500 North Broad Street, Philadelphia, PA, 19140.
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17
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Intra-axonal protein synthesis in development and beyond. Int J Dev Neurosci 2016; 55:140-149. [PMID: 26970010 DOI: 10.1016/j.ijdevneu.2016.03.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/03/2016] [Accepted: 03/07/2016] [Indexed: 12/15/2022] Open
Abstract
Proteins can be locally produced in the periphery of a cell, allowing a rapid and spatially precise response to the changes in its environment. This process is especially relevant in highly polarized and morphologically complex cells such as neurons. The study of local translation in axons has evolved from being primarily focused on developing axons, to the notion that also mature axons can produce proteins. Axonal translation has been implied in several physiological and pathological conditions, and in all cases it shares common molecular actors and pathways as well as regulatory mechanisms. Here, we review the main findings in these fields, and attempt to highlight shared principles.
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18
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Schwann Cell and Axon: An Interlaced Unit—From Action Potential to Phenotype Expression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 949:183-201. [DOI: 10.1007/978-3-319-40764-7_9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Sundaramoorthy V, Sultana JM, Atkin JD. Golgi fragmentation in amyotrophic lateral sclerosis, an overview of possible triggers and consequences. Front Neurosci 2015; 9:400. [PMID: 26578862 PMCID: PMC4621950 DOI: 10.3389/fnins.2015.00400] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/09/2015] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is an invariably fatal neurodegenerative disorder, which specifically targets motor neurons in the brain, brain stem and spinal cord. Whilst the etiology of ALS remains unknown, fragmentation of the Golgi apparatus is detected in ALS patient motor neurons and in animal/cellular disease models. The Golgi is a highly dynamic organelle that acts as a dispatching station for the vesicular transport of secretory/transmembrane proteins. It also mediates autophagy and maintains endoplasmic reticulum (ER) and axonal homeostasis. Both the trigger for Golgi fragmentation and the functional consequences of a fragmented Golgi apparatus in ALS remain unclear. However, recent evidence has highlighted defects in vesicular trafficking as a pathogenic mechanism in ALS. This review summarizes the evidence describing Golgi fragmentation in ALS, with possible links to other disease processes including cellular trafficking, ER stress, defective autophagy, and axonal degeneration.
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Affiliation(s)
- Vinod Sundaramoorthy
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney Sydney, NSW, Australia
| | - Jessica M Sultana
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney Sydney, NSW, Australia
| | - Julie D Atkin
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University Sydney Sydney, NSW, Australia ; Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, La Trobe University Melbourne, VIC, Australia
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20
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Chaudhury A, De Miranda-Neto MH, Pereira RVF, Zanoni JN. Myosin Va but Not nNOSα is Significantly Reduced in Jejunal Musculomotor Nerve Terminals in Diabetes Mellitus. Front Med (Lausanne) 2014; 1:17. [PMID: 25705628 PMCID: PMC4335397 DOI: 10.3389/fmed.2014.00017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 06/05/2014] [Indexed: 12/18/2022] Open
Abstract
Nitric oxide (NO) mediated slow inhibitory junction potential and mechanical relaxation after electrical field stimulation (EFS) is impaired in diabetes mellitus. Externally added NO donor restore nitrergic function, indicating that this reduction result from diminution of NO synthesis within the pre-junctional nerve terminals. The present study aimed to investigate two specific aims that may potentially provide pathophysiological insights into diabetic nitrergic neuropathy. Specifically, alteration in nNOSα contents within jejunal nerve terminals and a local subcortical transporter myosin Va was tested 16 weeks after induction of diabetes by low dose streptozotocin (STZ) in male Wistar rats. The results show that diabetic rats, in contrast to vehicle treated animals, have: (a) nearly absent myosin Va expression in nerve terminals of axons innervating smooth muscles and (b) significant decrease of myosin Va in neuronal soma of myenteric plexus. In contrast, nNOSα staining in diabetic jejunum neuromuscular strips showed near intact expression in neuronal cell bodies. The space occupancy of nitrergic nerve fibers was comparable between groups. Normal concentration of nNOSα was visualized within a majority of nitrergic terminals in diabetes, suggesting intact axonal transport of nNOSα to distant nerve terminals. These results reveal the dissociation between presences of nNOSα in the nerve terminals but deficiency of its transporter myosin Va in the jejunum of diabetic rats. This significant observation of reduced motor protein myosin Va within jejunal nerve terminals may potentially explain impairment of pre-junctional NO synthesis during EFS of diabetic gut neuromuscular strips despite presence of the nitrergic synthetic enzyme nNOSα.
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Affiliation(s)
- Arun Chaudhury
- Department of Surgery, Brigham and Women's Hospital, Harvard Medical School and VA Boston HealthCare System , West Roxbury, MA , USA
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21
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Abstract
Although neurons execute a cell intrinsic program of axonal growth during development, following the establishment of connections, the developmental growth capacity declines. Besides environmental challenges, this switch largely accounts for the failure of adult central nervous system (CNS) axons to regenerate. Here, we discuss the cell intrinsic control of axon regeneration, including not only the regulation of transcriptional and epigenetic mechanisms, but also the modulation of local protein translation, retrograde and anterograde axonal transport, and microtubule dynamics. We further explore the causes underlying the failure of CNS neurons to mount a vigorous regenerative response, and the paradigms demonstrating the activation of cell intrinsic axon growth programs. Finally, we present potential mechanisms to support axon regeneration, as these may represent future therapeutic approaches to promote recovery following CNS injury and disease.
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Affiliation(s)
- Fernando M Mar
- Nerve Regeneration Group Instituto de Biologia Molecular e Celular - IBMC University of Porto, Porto, Portugal
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22
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Verheijen MHG, Peviani M, Hendricusdottir R, Bell EM, Lammens M, Smit AB, Bendotti C, van Minnen J. Increased axonal ribosome numbers is an early event in the pathogenesis of amyotrophic lateral sclerosis. PLoS One 2014; 9:e87255. [PMID: 24498056 PMCID: PMC3907527 DOI: 10.1371/journal.pone.0087255] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 12/24/2013] [Indexed: 12/14/2022] Open
Abstract
Myelinating glia cells support axon survival and functions through mechanisms independent of myelination, and their dysfunction leads to axonal degeneration in several diseases. In amyotrophic lateral sclerosis (ALS), spinal motor neurons undergo retrograde degeneration, and slowing of axonal transport is an early event that in ALS mutant mice occurs well before motor neuron degeneration. Interestingly, in familial forms of ALS, Schwann cells have been proposed to slow disease progression. We demonstrated previously that Schwann cells transfer polyribosomes to diseased and regenerating axons, a possible rescue mechanism for disease-induced reductions in axonal proteins. Here, we investigated whether elevated levels of axonal ribosomes are also found in ALS, by analysis of a superoxide dismutase 1 (SOD1)G93A mouse model for human familial ALS and a patient suffering from sporadic ALS. In both cases, we found that the disorder was associated with an increase in the population of axonal ribosomes in myelinated axons. Importantly, in SOD1G93A mice, the appearance of axonal ribosomes preceded the manifestation of behavioral symptoms, indicating that upregulation of axonal ribosomes occurs early in the pathogenesis of ALS. In line with our previous studies, electron microscopy analysis showed that Schwann cells might serve as a source of axonal ribosomes in the disease-compromised axons. The early appearance of axonal ribosomes indicates an involvement of Schwann cells early in ALS neuropathology, and may serve as an early marker for disease-affected axons, not only in ALS, but also for other central and peripheral neurodegenerative disorders.
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Affiliation(s)
- Mark H. G. Verheijen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Marco Peviani
- Laboratory of Molecular Neurobiology, Department of Neuroscience, “Mario Negri” Institute for Pharmacological Research, Milan, Italy
| | - Rita Hendricusdottir
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Erin M. Bell
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
| | - Martin Lammens
- Department of Pathology, Antwerp University Hospital, University of Antwerp, Antwerp, Belgium
| | - August B. Smit
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Caterina Bendotti
- Laboratory of Molecular Neurobiology, Department of Neuroscience, “Mario Negri” Institute for Pharmacological Research, Milan, Italy
| | - Jan van Minnen
- Hotchkiss Brain Institute, University of Calgary, Calgary, Canada
- * E-mail:
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23
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González C, Couve A. The axonal endoplasmic reticulum and protein trafficking: Cellular bootlegging south of the soma. Semin Cell Dev Biol 2013; 27:23-31. [PMID: 24361785 DOI: 10.1016/j.semcdb.2013.12.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 11/18/2013] [Accepted: 12/05/2013] [Indexed: 12/26/2022]
Abstract
Neurons are responsible for the generation and propagation of electrical impulses, which constitute the central mechanism of information transfer between the nervous system and internal or external environments. Neurons are large and polarized cells with dendrites and axons constituting their major functional domains. Axons are thin and extremely long specializations that mediate the conduction of these electrical impulses. Regulation of the axonal proteome is fundamental to generate and maintain neural function. Although classical mechanisms of protein transport have been around for decades, a variety newly identified mechanisms to control the abundance of axonal proteins have appeared in recent years. Here we briefly describe the classical models of axonal transport and compare them to the emerging concepts of axonal biosynthesis centered on the endoplasmic reticulum. We review the structure of the axonal endoplasmic reticulum, and its role in diffusion and trafficking of axonal proteins. We also analyze the contribution of other secretory organelles to axonal trafficking and evaluate the potential consequences of axonal endoplasmic reticulum malfunction in neuropathology.
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Affiliation(s)
- Carolina González
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM) and Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile
| | - Andrés Couve
- Program of Physiology and Biophysics, Institute of Biomedical Sciences (ICBM) and Biomedical Neuroscience Institute (BNI), Faculty of Medicine, Universidad de Chile, Santiago, Chile.
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24
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Obara I, Hunt SP. Axonal protein synthesis and the regulation of primary afferent function. Dev Neurobiol 2013; 74:269-78. [PMID: 24085547 PMCID: PMC4237183 DOI: 10.1002/dneu.22133] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 08/27/2013] [Accepted: 09/15/2013] [Indexed: 11/09/2022]
Abstract
Local protein synthesis has been demonstrated in the peripheral processes of sensory primary afferents and is thought to contribute to the maintenance of the neuron, to neuronal plasticity following injury and also to regeneration of the axon after damage to the nerve. The mammalian target of rapamycin (mTOR), a master regulator of protein synthesis, integrates a variety of cues that regulate cellular homeostasis and is thought to play a key role in coordinating the neuronal response to environmental challenges. Evidence suggests that activated mTOR is expressed by peripheral nerve fibers, principally by A-nociceptors that rapidly signal noxious stimulation to the central nervous system, but also by a subset of fibers that respond to cold and itch. Inhibition of mTOR complex 1 (mTORC1) has shown that while the acute response to noxious stimulation is unaffected, more complex aspects of pain processing including the setting up and maintenance of chronic pain states can be disrupted suggesting a route for the generation of new drugs for the control of chronic pain. Given the role of mTORC1 in cellular homeostasis, it seems that systemic changes in the physiological state of the body such as occur during illness are likely to modulate the sensitivity of peripheral sensory afferents through mTORC1 signaling pathways.
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Affiliation(s)
- Ilona Obara
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, United Kingdom; School of Medicine, Pharmacy and Health, Durham University, Stockton-on-Tees TS17 6BH, United Kingdom
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25
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Sotelo JR, Canclini L, Kun A, Sotelo-Silveira JR, Calliari A, Cal K, Bresque M, DiPaolo A, Farias J, Mercer JA. Glia to axon RNA transfer. Dev Neurobiol 2013; 74:292-302. [DOI: 10.1002/dneu.22125] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Revised: 08/21/2013] [Accepted: 08/22/2013] [Indexed: 11/10/2022]
Affiliation(s)
- José Roberto Sotelo
- Department of Proteins and Nucleic Acids; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
| | - Lucía Canclini
- Department of Proteins and Nucleic Acids; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
| | - Alejandra Kun
- Department of Proteins and Nucleic Acids; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
- Biochemistry Section; School of Sciences, Universidad de la Republica; Montevideo Uruguay
| | - José Roberto Sotelo-Silveira
- Department of Genetics; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
- Department of Cell Biology; School of Sciences, Universidad de la Republica; Montevideo Uruguay
| | - Aldo Calliari
- Department of Biochemistry; Biophysics Area; Molecular and Cell Biology; School of Veterinary, Universidad de la República; Montevideo Uruguay
| | - Karina Cal
- Department of Proteins and Nucleic Acids; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
| | - Mariana Bresque
- Department of Proteins and Nucleic Acids; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
| | - Andrés DiPaolo
- Department of Proteins and Nucleic Acids; Instituto de Investigaciones Biológicas Clemente Estable; Montevideo Uruguay
| | - Joaquina Farias
- Biochemistry Section; School of Sciences, Universidad de la Republica; Montevideo Uruguay
| | - John A. Mercer
- Professor, McLaughlin Research Institute, Great Falls; Montana 59405-4900
- Cardiovascular Biology and Disease; Cardiomyopathies; Institute for Stem Cell Biology and Regenerative Medicine, National Center for Biological Sciences, Tata Institute for Fundamental Research; Bangalore 560065 India
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26
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Canclini L, Wallrabe H, Di Paolo A, Kun A, Calliari A, Sotelo-Silveira JR, Sotelo JR. Association of Myosin Va and Schwann cells-derived RNA in mammal myelinated axons, analyzed by immunocytochemistry and confocal FRET microscopy. Methods 2013; 66:153-61. [PMID: 23791767 DOI: 10.1016/j.ymeth.2013.06.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 06/06/2013] [Accepted: 06/10/2013] [Indexed: 11/19/2022] Open
Abstract
Evidence from multiple sources supports the hypothesis that Schwann cells in the peripheral nervous system transfer messenger RNA and ribosomes to the axons they ensheath. Several technical and methodological difficulties exist for investigators to unravel this process in myelinated axons - a complex two-cell unit. We present an experimental design to demonstrate that newly synthesized RNA is transferred from Schwann cells to axons in association with Myosin Va. The use of quantitative confocal FRET microscopy to track newly-synthesized RNA and determine the molecular association with Myosin Va, is described in detail.
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Affiliation(s)
- Lucía Canclini
- Departamento de Proteínas y Acidos Nucleicos, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, CP 11600, Uruguay.
| | - Horst Wallrabe
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904-4328, USA.
| | - Andrés Di Paolo
- Departamento de Proteínas y Acidos Nucleicos, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, CP 11600, Uruguay.
| | - Alejandra Kun
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904-4328, USA; Sección Bioquímica, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, CP 11400, Uruguay.
| | - Aldo Calliari
- Departamento de Proteínas y Acidos Nucleicos, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, CP 11600, Uruguay; Area Biofísica, Departamento de Bioquímica, Biología Celular y Molecular, Facultad de Veterinaria, Alberto Lasplaces 1550, Montevideo, CP 11600, Uruguay.
| | - José Roberto Sotelo-Silveira
- Departamento de Genética, Instituto de Investigaciones Biológicas Clemente Estable, Av Italia 3318, Montevideo, CP 11600, Uruguay; Departamento de Biología Celular, Facultad de Ciencias, Universidad de la República, Iguá 4225, Montevideo, CP 11400, Uruguay.
| | - José Roberto Sotelo
- Departamento de Proteínas y Acidos Nucleicos, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, CP 11600, Uruguay.
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27
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Sotelo JR, Canclini L, Kun A, Sotelo-Silveira JR, Xu L, Wallrabe H, Calliari A, Rosso G, Cal K, Mercer JA. Myosin-Va-dependent cell-to-cell transfer of RNA from Schwann cells to axons. PLoS One 2013; 8:e61905. [PMID: 23626749 PMCID: PMC3633983 DOI: 10.1371/journal.pone.0061905] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 03/15/2013] [Indexed: 01/30/2023] Open
Abstract
To better understand the role of protein synthesis in axons, we have identified the source of a portion of axonal RNA. We show that proximal segments of transected sciatic nerves accumulate newly-synthesized RNA in axons. This RNA is synthesized in Schwann cells because the RNA was labeled in the complete absence of neuronal cell bodies both in vitro and in vivo. We also demonstrate that the transfer is prevented by disruption of actin and that it fails to occur in the absence of myosin-Va. Our results demonstrate cell-to-cell transfer of RNA and identify part of the mechanism required for transfer. The induction of cell-to-cell RNA transfer by injury suggests that interventions following injury or degeneration, particularly gene therapy, may be accomplished by applying them to nearby glial cells (or implanted stem cells) at the site of injury to promote regeneration.
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Affiliation(s)
- José R. Sotelo
- Department of Proteins and Nucleic Acids, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
- * E-mail: (JRS); (JAM)
| | - Lucía Canclini
- Department of Proteins and Nucleic Acids, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Alejandra Kun
- Department of Proteins and Nucleic Acids, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
- Biochemistry Section, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - José R. Sotelo-Silveira
- Department of Genetics, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
- Cell Biology Department, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Lei Xu
- McLaughlin Research Institute, Great Falls, Montana, United States of America
| | - Horst Wallrabe
- Department of Biology, University of Virginia, Charlottesville, Virginia, United States of America
| | - Aldo Calliari
- Biophysics Area, Department of Biochemistry, Molecular and Cell Biology, Facultad de Veterinaria, Universidad de la República, Montevideo, Uruguay
| | - Gonzalo Rosso
- Department of Proteins and Nucleic Acids, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - Karina Cal
- Department of Proteins and Nucleic Acids, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay
| | - John A. Mercer
- McLaughlin Research Institute, Great Falls, Montana, United States of America
- Institute for Stem Cell Biology and Regenerative Medicine, National Centre for Biological Sciences, Bangalore, India
- * E-mail: (JRS); (JAM)
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28
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Jung H, Yoon BC, Holt CE. Axonal mRNA localization and local protein synthesis in nervous system assembly, maintenance and repair. Nat Rev Neurosci 2012; 13:308-24. [PMID: 22498899 PMCID: PMC3682205 DOI: 10.1038/nrn3210] [Citation(s) in RCA: 337] [Impact Index Per Article: 28.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
mRNAs can be targeted to specific neuronal subcellular domains, which enables rapid changes in the local proteome through local translation. This mRNA-based mechanism links extrinsic signals to spatially restricted cellular responses and can mediate stimulus-driven adaptive responses such as dendritic plasticity. Local mRNA translation also occurs in growing axons where it can mediate directional responses to guidance signals. Recent profiling studies have revealed that both growing and mature axons possess surprisingly complex and dynamic transcriptomes, thereby suggesting that axonal mRNA localization is highly regulated and has a role in a broad range of processes, a view that is increasingly being supported by new experimental evidence. Here, we review current knowledge on the roles and regulatory mechanisms of axonal mRNA translation and discuss emerging links to axon guidance, survival, regeneration and neurological disorders.
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Affiliation(s)
- Hosung Jung
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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29
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Kun A, Canclini L, Rosso G, Bresque M, Romeo C, Hanusz A, Cal K, Calliari A, Sotelo Silveira J, Sotelo JR. F-actin distribution at nodes of Ranvier and Schmidt-Lanterman incisures in mammalian sciatic nerves. Cytoskeleton (Hoboken) 2012; 69:486-95. [PMID: 22328339 DOI: 10.1002/cm.21011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 01/18/2012] [Accepted: 01/18/2012] [Indexed: 11/10/2022]
Abstract
Very little is known about the function of the F-actin cytoskeleton in the regeneration and pathology of peripheral nerve fibers. The actin cytoskeleton has been associated with maintenance of tissue structure, transmission of traction and contraction forces, and an involvement in cell motility. Therefore, the state of the actin cytoskeleton strongly influences the mechanical properties of cells and intracellular transport therein. In this work, we analyze the distribution of F-actin at Schmidt-Lanterman Incisures (SLI) and nodes of Ranvier (NR) domains in normal, regenerating and pathologic Trembler J (TrJ/+) sciatic nerve fibers, of rats and mice. F-actin was quantified and it was found increased in TrJ/+, both in SLI and NR. However, SLI and NR of regenerating rat sciatic nerve did not show significant differences in F-actin, as compared with normal nerves. Cytochalasin-D and Latrunculin-A were used to disrupt the F-actin network in normal and regenerating rat sciatic nerve fibers. Both drugs disrupt F-actin, but in different ways. Cytochalasin-D did not disrupt Schwann cell (SC) F-actin at the NR. Latrunculin-A did not disrupt F-actin at the boundary region between SC and axon at the NR domain. We surmise that the rearrangement of F-actin in neurological disorders, as presented here, is an important feature of TrJ/+ pathology as a Charcot-Marie-Tooth (CMT) model.
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Affiliation(s)
- Alejandra Kun
- Department of Proteins and Nucleic Acids, Instituto de Investigaciones Biológicas Clemente Estable, Av. Italia 3318, Montevideo, Uruguay
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30
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Walker BA, Hengst U, Kim HJ, Jeon NL, Schmidt EF, Heintz N, Milner TA, Jaffrey SR. Reprogramming axonal behavior by axon-specific viral transduction. Gene Ther 2012; 19:947-55. [PMID: 22278412 DOI: 10.1038/gt.2011.217] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The treatment of axonal disorders, such as diseases associated with axonal injury and degeneration, is limited by the inability to directly target therapeutic protein expression to injured axons. Current gene therapy approaches rely on infection and transcription of viral genes in the cell body. Here, we describe an approach to target gene expression selectively to axons. Using a genetically engineered mouse containing epitope-labeled ribosomes, we find that neurons in adult animals contain ribosomes in distal axons. To use axonal ribosomes to alter local protein expression, we utilized a Sindbis virus containing an RNA genome that has been modified so that it can be directly used as a template for translation. Selective application of this virus to axons leads to local translation of heterologous proteins. Furthermore, we demonstrate that selective axonal protein expression can be used to modify axonal signaling in cultured neurons, enabling axons to grow over inhibitory substrates typically encountered following axonal injury. We also show that this viral approach also can be used to achieve heterologous expression in axons of living animals, indicating that this approach can be used to alter the axonal proteome in vivo. Together, these data identify a novel strategy to manipulate protein expression in axons, and provides a novel approach for using gene therapies for disorders of axonal function.
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Affiliation(s)
- B A Walker
- Department of Pharmacology, Weill Medical College, Cornell University, New York, NY 10065, USA
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31
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Abstract
The conclusive demonstration of RNA in vertebrate axons by in situ hybridization (ISH) has been elusive. We review the most important reasons for difficulties, including low concentration of axonal RNAs, localization in specific cortical domains, and the need to isolate axons. We demonstrate the importance of axon micro-dissection to obtain a whole mount perspective of mRNA distribution in the axonal territory. We describe a protocol to perform fluorescent ISH in isolated axons and guidelines for the preservation of structural and molecular integrity of cortical RNA-containing domains (e.g., Periaxoplasmic Ribosomal Plaques, or PARPs) in isolated axoplasm.
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Court FA, Midha R, Cisterna BA, Grochmal J, Shakhbazau A, Hendriks WT, Van Minnen J. Morphological evidence for a transport of ribosomes from Schwann cells to regenerating axons. Glia 2011; 59:1529-39. [PMID: 21656857 DOI: 10.1002/glia.21196] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 05/16/2011] [Indexed: 11/11/2022]
Abstract
Recently, we showed that Schwann cells transfer ribosomes to injured axons. Here, we demonstrate that Schwann cells transfer ribosomes to regenerating axons in vivo. For this, we used lentiviral vector-mediated expression of ribosomal protein L4 and eGFP to label ribosomes in Schwann cells. Two approaches were followed. First, we transduced Schwann cells in vivo in the distal trunk of the sciatic nerve after a nerve crush. Seven days after the crush, 12% of regenerating axons contained fluorescent ribosomes. Second, we transduced Schwann cells in vitro that were subsequently injected into an acellular nerve graft that was inserted into the sciatic nerve. Fluorescent ribosomes were detected in regenerating axons up to 8 weeks after graft insertion. Together, these data indicate that regenerating axons receive ribosomes from Schwann cells and, furthermore, that Schwann cells may support local axonal protein synthesis by transferring protein synthetic machinery and mRNAs to these axons.
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Affiliation(s)
- Felipe A Court
- Millennium Nucleus for Regenerative Biology, Faculty of Biology, P. Catholic University of Chile, Chile
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33
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Verheijen MHG, Lammens M, Ceuterick-de Groote C, Timmerman V, De Jonghe P, King RHM, Smit AB, van Minnen J. Increased axonal ribosome numbers in CMT diseases. J Peripher Nerv Syst 2011; 16:71-3. [DOI: 10.1111/j.1529-8027.2011.00322.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Crispino M, Cefaliello C, Kaplan B, Giuditta A. Protein synthesis in nerve terminals and the glia-neuron unit. Results Probl Cell Differ 2010; 48:243-67. [PMID: 19554280 DOI: 10.1007/400_2009_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The progressive philogenetic lengthening of axonal processes and the increase in complexity of terminal axonal arborizations markedly augmented the demands of the neuronal cytoplasmic mass on somatic gene expression. It is proposed that in an adaptive response to this challenge, novel gene expression functions developed in the axon compartment, consisting of axonal and presynaptic translation systems that rely on the delivery of transcripts synthesized in adjacent glial cells. Such intercellular mode of gene expression would allow more rapid plastic changes to occur in spatially restricted neuronal domains, down to the size of individual synapses. The cell body contribution to local gene expression in well-differentiated neurons remains to be defined. The history of this concept and the experimental evidence supporting its validity are critically discussed in this article. The merit of this perspective lies with the recognition that plasticity events represent a major occurrence in the brain, and that they largely occur at synaptic sites, including presynaptic endings.
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Affiliation(s)
- Marianna Crispino
- Department of Biological Sciences, University of Naples Federico II, Naples, Italy
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35
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Abstract
Periaxoplasmic ribosomal plaques (PARPs) are systematically recurring ribosome-containing structural domains located in the F-actin-rich periphery of axoplasm in myelinated fibers. In contrast, endoaxoplasmic ribosomal plaques (EARPs) are small, oval-shaped ribosomal aggregate structures randomly dispersed within the axoplasm of unmyelinated squid giant axons. Ribosomes are attached to a superficial plaque-like structural matrix, which "caps" the domain at the outer cortical margin and appears fragmented in subcortical axoplasm. As such, the matrix represents a novel hallmark of PARP domains. Molecular markers concentrated in PARP domains include beta-actin mRNA, ZBP-1, SRP54, myosin Va and kinesin II molecular motor proteins. Rapid axoplasmic transport of microinjected heterologous radiolabeled BC1 RNA to putative PARP domains, mediated pari passu by microtubule- and F-actin-dependent systems, suggests that translation machinery, anchored by the matrix could provide targeted destinations for RNA trafficking. As distributed local centers of protein synthesis along axons, PARPs are likely to share modes of expression in common with other translational subdomains in neurons.
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36
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Szaro BG, Strong MJ. Post-transcriptional control of neurofilaments: New roles in development, regeneration and neurodegenerative disease. Trends Neurosci 2010; 33:27-37. [DOI: 10.1016/j.tins.2009.10.002] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2009] [Revised: 09/21/2009] [Accepted: 10/06/2009] [Indexed: 12/17/2022]
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37
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Sal'nikov VV, Mishagina EA, Kozlovskaya IB, Nikolsky EE, Islamov RR. Immunohistochemical confirmation of localization of the ribosomal protein L26 in the terminal buttons of rat motor axon. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2009; 427:313-315. [PMID: 19760869 DOI: 10.1134/s0012496609040024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Affiliation(s)
- V V Sal'nikov
- Kazan Institute Biochemistry and Biophysics, Kazan Scientific Center Russian Academy of Sciences, Kazan, Tatarstan, Russia
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Gumy LF, Tan CL, Fawcett JW. The role of local protein synthesis and degradation in axon regeneration. Exp Neurol 2009; 223:28-37. [PMID: 19520073 PMCID: PMC2864402 DOI: 10.1016/j.expneurol.2009.06.004] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2009] [Revised: 06/02/2009] [Accepted: 06/02/2009] [Indexed: 11/26/2022]
Abstract
In axotomised regenerating axons, the first step toward successful regeneration is the formation of a growth cone. This requires a variety of dynamic morphological and biochemical changes in the axon, including the appearance of many new cytoskeletal, cell surface and signalling molecules. These changes suggest the activation of coordinated complex cellular processes. A recent development has been the demonstration that the regenerative ability of some axons depends on their capacity to locally synthesise new proteins and degrade others at the injury site autonomously from the cell body. There are also events involving the degradation of cytoskeletal and other molecules, and activation of signalling pathways, with axotomy-induced calcium changes probably being an initiating event. A future challenge will be to understand how this complex network of processes interacts in order to find therapeutic ways of promoting the regeneration of CNS axons.
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Affiliation(s)
| | | | - James W. Fawcett
- Corresponding author. Cambridge Centre for Brain Repair, E.D. Adrian Building, Forvie Site, Robinson Way, Cambridge CB2 0PY, UK. Fax: +44 1223 331174.
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Bisbal M, Wojnacki J, Peretti D, Ropolo A, Sesma J, Jausoro I, Cáceres A. KIF4 mediates anterograde translocation and positioning of ribosomal constituents to axons. J Biol Chem 2009; 284:9489-97. [PMID: 19158085 PMCID: PMC2666601 DOI: 10.1074/jbc.m808586200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2008] [Revised: 12/29/2008] [Indexed: 12/18/2022] Open
Abstract
In this study, we have used a combination of biochemical and molecular biology techniques to demonstrate that the C-terminal tail domain of KIF4 directly interacts with P0, a major protein component of ribosomes. Besides, in dorsal root ganglion neurons, KIF4 and P0, as well as other ribosomal constituents, colocalize in clusters distributed along axons and neuritic tips. RNA interference suppression of KIF4 or expression of KIF4 variants lacking the tail domain or mutations of the ATP-binding site result in accumulation of P0 and other ribosomal proteins at the cell body and in their disappearance from axons. Our results also show one additional function for KIF4 involving an Ezrin-Radixin-Moesin-like domain in the second coiled-coiled region of KIF4. Expression of a KIF4 mutant lacking this domain abolishes the clustering of ribosomal constituents and prevents the anterograde translocation of the cell adhesion molecule L1. Taken together, the present results suggest that by binding to P0 through its tail domain and by using its motor activity, KIF4 is involved in the anterograde trafficking of ribosomal constituents to axons and that by means of its Ezrin-Radixin-Moesin-like domain interacts and transports L1.
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Affiliation(s)
- Mariano Bisbal
- Laboratory of Neurobiology and Cell Biology, Instituto Investigación Médica Mercedes y Martín Ferreyra-Consejo Nacional de Investigaciones Científicas y Técnicas, 5016 Córdoba, Argentina
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40
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Giuditta A, Tai Chun J, Eyman M, Cefaliello C, Bruno AP, Crispino M. Local Gene Expression in Axons and Nerve Endings: The Glia-Neuron Unit. Physiol Rev 2008; 88:515-55. [DOI: 10.1152/physrev.00051.2006] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Neurons have complex and often extensively elongated processes. This unique cell morphology raises the problem of how remote neuronal territories are replenished with proteins. For a long time, axonal and presynaptic proteins were thought to be exclusively synthesized in the cell body, which delivered them to peripheral sites by axoplasmic transport. Despite this early belief, protein has been shown to be synthesized in axons and nerve terminals, substantially alleviating the trophic burden of the perikaryon. This observation raised the question of the cellular origin of the peripheral RNAs involved in protein synthesis. The synthesis of these RNAs was initially attributed to the neuron soma almost by default. However, experimental data and theoretical considerations support the alternative view that axonal and presynaptic RNAs are also transcribed in the flanking glial cells and transferred to the axon domain of mature neurons. Altogether, these data suggest that axons and nerve terminals are served by a distinct gene expression system largely independent of the neuron cell body. Such a local system would allow the neuron periphery to respond promptly to environmental stimuli. This view has the theoretical merit of extending to axons and nerve terminals the marginalized concept of a glial supply of RNA (and protein) to the neuron cell body. Most long-term plastic changes requiring de novo gene expression occur in these domains, notably in presynaptic endings, despite their intrinsic lack of transcriptional capacity. This review enlightens novel perspectives on the biology and pathobiology of the neuron by critically reviewing these issues.
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Sotelo-Silveira J, Crispino M, Puppo A, Sotelo JR, Koenig E. Myelinated axons contain beta-actin mRNA and ZBP-1 in periaxoplasmic ribosomal plaques and depend on cyclic AMP and F-actin integrity for in vitro translation. J Neurochem 2007; 104:545-57. [PMID: 17961153 DOI: 10.1111/j.1471-4159.2007.04999.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Periaxoplasmic ribosomal plaques (PARPs) are periodic structural formations containing ribosomes, which are likely cortical sites of translation along myelinated fibers. beta-actin mRNA, and its trans-acting binding factor, zipcode-binding protein-1, were co-distributed within PARP domains of axoplasmic whole-mounts isolated from goldfish Mauthner, rabbit and rat nerve fibers. The distribution of co-localization signals of fluorophore pixels, however, was asymmetric in PARP domains, possibly indicative of endpoint trafficking of RNPs. beta-actin mRNA in RNA extracted from axoplasm of single Mauthner fibers was confirmed by RT-PCR. A metabolically active isolated Mauthner fiber system, which required cAMP to activate translation, was developed in order to probe cycloheximide-sensitivity, and the importance of the actin cytoskeleton. cAMP greatly stimulated protein synthesis in axoplasm after a period of pre-incubation, while being inhibited strongly by cycloheximide, or by cytochalasin D. Cytochalasin D reduced incorporation only modestly in the associated myelin sheath. We conclude that mechanisms for targeting and localizing beta-actin mRNA to discrete PARP domains are probably similar to those described for dendritic synaptic domains. Moreover, optimal translation in axoplasm depends on the integrity of the actin cytoskeleton, and can be modulated by cAMP as well.
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Affiliation(s)
- José Sotelo-Silveira
- Department of Protein and Nucleic Acids, Instituto de Investigaciones Biologicas Clemente Estable, Montevideo, Uruguay
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