201
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Retrograde apoptotic signaling by the p75 neurotrophin receptor. Neuronal Signal 2017; 1:NS20160007. [PMID: 32714573 PMCID: PMC7373242 DOI: 10.1042/ns20160007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/23/2017] [Accepted: 01/25/2017] [Indexed: 02/06/2023] Open
Abstract
Neurotrophins are target-derived factors necessary for mammalian nervous system development and maintenance. They are typically produced by neuronal target tissues and interact with their receptors at axonal endings. Therefore, locally generated neurotrophin signals must be conveyed from the axon back to the cell soma. Retrograde survival signaling by neurotrophin binding to Trk receptors has been extensively studied. However, neurotrophins also bind to the p75 receptor, which can induce apoptosis in a variety of contexts. Selective activation of p75 at distal axon ends has been shown to generate a retrograde apoptotic signal, although the mechanisms involved are poorly understood. The present review summarizes the available evidence for retrograde proapoptotic signaling in general and the role of the p75 receptor in particular, with discussion of unanswered questions in the field. In-depth knowledge of the mechanisms of retrograde apoptotic signaling is essential for understanding the etiology of neurodegeneration in many diseases and injuries.
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202
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Hisamoto N, Matsumoto K. Signal transduction cascades in axon regeneration: insights from C. elegans. Curr Opin Genet Dev 2017; 44:54-60. [PMID: 28213159 DOI: 10.1016/j.gde.2017.01.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/13/2017] [Accepted: 01/26/2017] [Indexed: 02/07/2023]
Abstract
Axon regeneration after nerve injury is a conserved biological process in many animals, including humans. The nematode Caenorhabditis elegans (C. elegans) has recently emerged as a genetically tractable model for studying regenerative responses in neurons. Extensive studies over several years using this organism have revealed a number of intrinsic and extrinsic signal transduction cascades that regulate axon regeneration, and these are found to be conserved from worms to humans. Further studies have demonstrated that these cascades consist of several signaling networks that ultimately merge into the c-Jun N-terminal kinase (JNK) cascade. In this review, we describe some recent insights into the signaling cascades controlling axon regeneration in C. elegans and describe their conserved roles in other organisms including mammals.
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Affiliation(s)
- Naoki Hisamoto
- Department of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Kunihiro Matsumoto
- Department of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
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203
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Lombardi L, Persiconi I, Gallo A, Hoogenraad CC, De Stefano ME. NGF-dependent axon growth and regeneration are altered in sympathetic neurons of dystrophic mdx mice. Mol Cell Neurosci 2017; 80:1-17. [PMID: 28161362 DOI: 10.1016/j.mcn.2017.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 12/09/2016] [Accepted: 01/29/2017] [Indexed: 12/18/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a lethal disease, determined by lack of dystrophin (Dp427), a muscular cytoskeletal protein also expressed by selected neuronal populations. Consequently, besides muscular wasting, both human patients and DMD animal models suffer several neural disorders. In previous studies on the superior cervical ganglion (SCG) of wild type and dystrophic mdx mice (Lombardi et al. 2008), we hypothesized that Dp427 could play some role in NGF-dependent axonal growth, both during development and adulthood. To address this issue, we first analyzed axon regeneration potentials of SCG neurons of both genotypes after axotomy in vivo. While noradrenergic innervation of mdx mouse submandibular gland, main source of nerve growth factor (NGF), recovered similarly to wild type, iris innervation (muscular target) never did. We, therefore, evaluated whether dystrophic SCG neurons were poorly responsive to NGF, especially at low concentration. Following in vitro axotomy in the presence of either 10 or 50ng/ml NGF, the number of regenerated axons in mdx mouse neuron cultures was indeed reduced, compared to wild type, at the lower concentration. Neurite growth parameters (i.e. number, length), growth cone dynamics and NGF/TrkA receptor signaling in differentiating neurons (not injured) were also significantly reduced when cultured with 10ng/ml NGF, but also with higher NGF concentrations. In conclusion, we propose a role for Dp427 in NGF-dependent cytoskeletal dynamics associated to growth cone advancement, possibly through indirect stabilization of TrkA receptors. Considering NGF activity in nervous system development/remodeling, this aspect could concur in some of the described DMD-associated neural dysfunctions.
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Affiliation(s)
- Loredana Lombardi
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy
| | - Irene Persiconi
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy
| | - Alessandra Gallo
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy
| | - Casper C Hoogenraad
- Cell Biology, Faculty of Science, Utrecht University, 3584CH Utrecht, The Netherlands
| | - Maria Egle De Stefano
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, Laboratory affiliated to Istituto Pasteur Italia - Fondazione Cenci Bolognetti, 00185 Roma, Italy; Center for Research in Neurobiology "Daniel Bovet", Sapienza Università di Roma, 00185 Roma, Italy.
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204
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Restoring GM1 ganglioside expression ameliorates axonal outgrowth inhibition and cognitive impairments induced by blast traumatic brain injury. Sci Rep 2017; 7:41269. [PMID: 28112258 PMCID: PMC5255550 DOI: 10.1038/srep41269] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 12/19/2016] [Indexed: 01/01/2023] Open
Abstract
Blast induced traumatic brain injury (B-TBI) may cause various degrees of cognitive and behavioral disturbances but the exact brain pathophysiology involved is poorly understood. It was previously suggested that ganglioside alteration on the axon surface as well as axonal regenerating inhibitors (ARIs) such as myelin associated glycoprotein (MAG) were involved in axonal outgrowth inhibition (AOI), leading to brain damage. GM1 ganglioside content in the brain was significantly reduced while GD1 ganglioside was not affected. The axonal regeneration was also reduced as seen by the phosphorylated NF-H expression. Moreover, B-TBI induced a significant elevation in MAG expression in the brains of the injured mice. The blast injured mice exhibited a significant decline in spatial memory as seen by the Y-maze test. In addition, the injured mice showed pronounced damage to the visual memory (as evaluated by the Novel object recognition test). A single low dose of GM1 (2 mg/kg; IP), shortly after the injury, prevented both the cognitive and the cellular changes in the brains of the injured mice. These results enlighten part of the complicated mechanism that underlies the damage induced by B-TBI and may also suggest a potential new treatment strategy for brain injuries.
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205
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Lackington WA, Ryan AJ, O'Brien FJ. Advances in Nerve Guidance Conduit-Based Therapeutics for Peripheral Nerve Repair. ACS Biomater Sci Eng 2017; 3:1221-1235. [PMID: 33440511 DOI: 10.1021/acsbiomaterials.6b00500] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Peripheral nerve injuries have high incidence rates, limited treatment options and poor clinical outcomes, rendering a significant socioeconomic burden. For effective peripheral nerve repair, the gap or site of injury must be structurally bridged to promote correct reinnervation and functional regeneration. However, effective repair becomes progressively more difficult with larger gaps. Autologous nerve grafting remains the best clinical option for the repair of large gaps (20-80 mm) despite being associated with numerous limitations including permanent donor site morbidity, a lack of available tissue and the formation of neuromas. To meet the clinical demand of large gap repair and overcome these limitations, tissue engineering has led to the development of nerve guidance conduit-based therapeutics. This review focuses on the advances of nerve guidance conduit-based therapeutics in terms of their structural properties including biomimetic composition, permeability, architecture, and surface modifications. Associated biochemical properties, pertaining to the incorporation of cells and neurotrophic factors, are also reviewed. After reviewing the progress in the field, we conclude by presenting an outlook on their clinical translatability and the next generation of therapeutics.
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Affiliation(s)
- William A Lackington
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland, Dublin 2, Ireland.,Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin and Royal College of Surgeons in Ireland, Dublin 2, Ireland.,Trinity Centre for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Ireland
| | - Alan J Ryan
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland, Dublin 2, Ireland.,Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin and Royal College of Surgeons in Ireland, Dublin 2, Ireland.,Trinity Centre for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Ireland
| | - Fergal J O'Brien
- Tissue Engineering Research Group (TERG), Department of Anatomy, Royal College of Surgeons in Ireland, Dublin 2, Ireland.,Advanced Materials and Bioengineering Research Centre (AMBER), Trinity College Dublin and Royal College of Surgeons in Ireland, Dublin 2, Ireland.,Trinity Centre for Bioengineering (TCBE), Trinity College Dublin, Dublin 2, Ireland
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206
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Phosphorylation of Drebrin and Its Role in Neuritogenesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1006:49-60. [PMID: 28865014 DOI: 10.1007/978-4-431-56550-5_4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Neuritogenesis is an early event in neuronal development in which newborn neurons first form growth cones, as a prerequisite for the formation of axons and dendrites. Growth cones emerge from segmented regions of the lamellipodium of embryonic neurons and grow away from the cell body leaving behind a neurite that will eventually polarise into an axon or dendrite. Growth cones also function to navigate precise routes through the embryo to locate an appropriate synaptic partner. Dynamic interactions between two components of the neuronal cytoskeleton, actin filaments and microtubules, are known to be essential for growth cone formation and hence neuritogenesis. The molecular mechanisms that coordinate interactions between actin filaments and dynamic microtubules during neuritogenesis are beginning to be understood. One candidate pathway coupling actin filaments to microtubules consists of the actin filament-binding protein drebrin and the microtubule-binding +TIP protein EB3. This pathway is regulated proximally by cyclin-dependent kinase 5 phosphorylation of drebrin but the upstream elements in the pathway have yet to be identified.
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207
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Shin JE, Cho Y. Epigenetic Regulation of Axon Regeneration after Neural Injury. Mol Cells 2017; 40:10-16. [PMID: 28152303 PMCID: PMC5303884 DOI: 10.14348/molcells.2017.2311] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/16/2017] [Accepted: 01/23/2017] [Indexed: 12/16/2022] Open
Abstract
When peripheral axons are damaged, neuronal injury signaling pathways induce transcriptional changes that support axon regeneration and consequent functional recovery. The recent development of bioinformatics techniques has allowed for the identification of many of the regeneration-associated genes that are regulated by neural injury, yet it remains unclear how global changes in transcriptome are coordinated. In this article, we review recent studies on the epigenetic mechanisms orchestrating changes in gene expression in response to nerve injury. We highlight the importance of epigenetic mechanisms in discriminating efficient axon regeneration in the peripheral nervous system and very limited axon regrowth in the central nervous system and discuss the therapeutic potential of targeting epigenetic regulators to improve neural recovery.
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Affiliation(s)
- Jung Eun Shin
- The Research Institute of Basic Sciences, Seoul National University, Seoul 08826,
Korea
| | - Yongcheol Cho
- Department of Life Sciences, Korea University, Seoul 02841,
Korea
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208
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Cartoni R, Norsworthy MW, Bei F, Wang C, Li S, Zhang Y, Gabel CV, Schwarz TL, He Z. The Mammalian-Specific Protein Armcx1 Regulates Mitochondrial Transport during Axon Regeneration. Neuron 2016; 92:1294-1307. [PMID: 28009275 PMCID: PMC5189716 DOI: 10.1016/j.neuron.2016.10.060] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 08/14/2016] [Accepted: 10/20/2016] [Indexed: 11/29/2022]
Abstract
Mitochondrial transport is crucial for neuronal and axonal physiology. However, whether and how it impacts neuronal injury responses, such as neuronal survival and axon regeneration, remain largely unknown. In an established mouse model with robust axon regeneration, we show that Armcx1, a mammalian-specific gene encoding a mitochondria-localized protein, is upregulated after axotomy in this high regeneration condition. Armcx1 overexpression enhances mitochondrial transport in adult retinal ganglion cells (RGCs). Importantly, Armcx1 also promotes both neuronal survival and axon regeneration after injury, and these effects depend on its mitochondrial localization. Furthermore, Armcx1 knockdown undermines both neuronal survival and axon regeneration in the high regenerative capacity model, further supporting a key role of Armcx1 in regulating neuronal injury responses in the adult central nervous system (CNS). Our findings suggest that Armcx1 controls mitochondrial transport during neuronal repair.
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Affiliation(s)
- Romain Cartoni
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA.
| | - Michael W Norsworthy
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Fengfeng Bei
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Chen Wang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Siwei Li
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Yiling Zhang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher V Gabel
- Department of Physiology and Biophysics, Photonics Center, Boston University School of Medicine, Boston, MA 02118, USA
| | - Thomas L Schwarz
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA.
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209
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Qu Y, Hahn I, Webb SED, Pearce SP, Prokop A. Periodic actin structures in neuronal axons are required to maintain microtubules. Mol Biol Cell 2016; 28:296-308. [PMID: 27881663 PMCID: PMC5231898 DOI: 10.1091/mbc.e16-10-0727] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 11/09/2016] [Accepted: 11/15/2016] [Indexed: 12/31/2022] Open
Abstract
Drosophila genetics is combined with high-resolution microscopy and a number of functional readouts to demonstrate key factors required for the presence of regularly spaced rings of cortical actin in axons. The data suggest important roles for the actin rings in microtubule regulation, most likely by sustaining their polymerization. Axons are cable-like neuronal processes wiring the nervous system. They contain parallel bundles of microtubules as structural backbones, surrounded by regularly spaced actin rings termed the periodic membrane skeleton (PMS). Despite being an evolutionarily conserved, ubiquitous, highly ordered feature of axons, the function of PMS is unknown. Here we studied PMS abundance, organization, and function, combining versatile Drosophila genetics with superresolution microscopy and various functional readouts. Analyses with 11 actin regulators and three actin-targeting drugs suggest that PMS contains short actin filaments that are depolymerization resistant and sensitive to spectrin, adducin, and nucleator deficiency, consistent with microscopy-derived models proposing PMS as specialized cortical actin. Upon actin removal, we observed gaps in microtubule bundles, reduced microtubule polymerization, and reduced axon numbers, suggesting a role of PMS in microtubule organization. These effects become strongly enhanced when carried out in neurons lacking the microtubule-stabilizing protein Short stop (Shot). Combining the aforementioned actin manipulations with Shot deficiency revealed a close correlation between PMS abundance and microtubule regulation, consistent with a model in which PMS-dependent microtubule polymerization contributes to their maintenance in axons. We discuss potential implications of this novel PMS function along axon shafts for axon maintenance and regeneration.
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Affiliation(s)
- Yue Qu
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Ines Hahn
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Stephen E D Webb
- Rutherford Appleton Laboratory, Science and Technology Facilities Council, Didcot OX11 0QX, United Kingdom
| | - Simon P Pearce
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom.,School of Mathematics, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Andreas Prokop
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester M13 9PT, United Kingdom
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210
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Differential regenerative ability of sensory and motor neurons. Neurosci Lett 2016; 652:35-40. [PMID: 27818349 DOI: 10.1016/j.neulet.2016.11.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 10/24/2016] [Accepted: 11/01/2016] [Indexed: 11/22/2022]
Abstract
After injury, the adult mammalian central nervous system (CNS) lacks long-distance axon regeneration. This review discusses the similarities and differences of sensory and motor neurons, seeking to understand how to achieve functional sensory and motor regeneration. As these two types of neurons respond differently to axotomy, growth environment and treatment, the future challenge will be on how to achieve full recovery in a way that allows regeneration of both types of fibres simultaneously.
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211
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Chisholm AD, Hutter H, Jin Y, Wadsworth WG. The Genetics of Axon Guidance and Axon Regeneration in Caenorhabditis elegans. Genetics 2016; 204:849-882. [PMID: 28114100 PMCID: PMC5105865 DOI: 10.1534/genetics.115.186262] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022] Open
Abstract
The correct wiring of neuronal circuits depends on outgrowth and guidance of neuronal processes during development. In the past two decades, great progress has been made in understanding the molecular basis of axon outgrowth and guidance. Genetic analysis in Caenorhabditis elegans has played a key role in elucidating conserved pathways regulating axon guidance, including Netrin signaling, the slit Slit/Robo pathway, Wnt signaling, and others. Axon guidance factors were first identified by screens for mutations affecting animal behavior, and by direct visual screens for axon guidance defects. Genetic analysis of these pathways has revealed the complex and combinatorial nature of guidance cues, and has delineated how cues guide growth cones via receptor activity and cytoskeletal rearrangement. Several axon guidance pathways also affect directed migrations of non-neuronal cells in C. elegans, with implications for normal and pathological cell migrations in situations such as tumor metastasis. The small number of neurons and highly stereotyped axonal architecture of the C. elegans nervous system allow analysis of axon guidance at the level of single identified axons, and permit in vivo tests of prevailing models of axon guidance. C. elegans axons also have a robust capacity to undergo regenerative regrowth after precise laser injury (axotomy). Although such axon regrowth shares some similarities with developmental axon outgrowth, screens for regrowth mutants have revealed regeneration-specific pathways and factors that were not identified in developmental screens. Several areas remain poorly understood, including how major axon tracts are formed in the embryo, and the function of axon regeneration in the natural environment.
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Affiliation(s)
| | - Harald Hutter
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, and
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
- Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, Chevy Chase, Maryland, and
| | - William G Wadsworth
- Department of Pathology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
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212
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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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213
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He M, Ding Y, Chu C, Tang J, Xiao Q, Luo ZG. Autophagy induction stabilizes microtubules and promotes axon regeneration after spinal cord injury. Proc Natl Acad Sci U S A 2016; 113:11324-11329. [PMID: 27638205 PMCID: PMC5056063 DOI: 10.1073/pnas.1611282113] [Citation(s) in RCA: 133] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Remodeling of cytoskeleton structures, such as microtubule assembly, is believed to be crucial for growth cone initiation and regrowth of injured axons. Autophagy plays important roles in maintaining cellular homoeostasis, and its dysfunction causes neuronal degeneration. The role of autophagy in axon regeneration after injury remains speculative. Here we demonstrate a role of autophagy in regulating microtubule dynamics and axon regeneration. We found that autophagy induction promoted neurite outgrowth, attenuated the inhibitory effects of nonpermissive substrate myelin, and decreased the formation of retraction bulbs following axonal injury in cultured cortical neurons. Interestingly, autophagy induction stabilized microtubules by degrading SCG10, a microtubule disassembly protein in neurons. In mice with spinal cord injury, local administration of a specific autophagy-inducing peptide, Tat-beclin1, to lesion sites markedly attenuated axonal retraction of spinal dorsal column axons and cortical spinal tract and promoted regeneration of descending axons following long-term observation. Finally, administration of Tat-beclin1 improved the recovery of motor behaviors of injured mice. These results show a promising effect of an autophagy-inducing reagent on injured axons, providing direct evidence supporting a beneficial role of autophagy in axon regeneration.
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Affiliation(s)
- Miao He
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuetong Ding
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Chen Chu
- Institute of Biochemistry and Cell Biology, State Key Laboratory of Molecular Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jing Tang
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qi Xiao
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhen-Ge Luo
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China; Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai 200031, China
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214
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Roman JA, Reucroft I, Martin RA, Hurtado A, Mao HQ. Local Release of Paclitaxel from Aligned, Electrospun Microfibers Promotes Axonal Extension. Adv Healthc Mater 2016; 5:2628-2635. [PMID: 27581383 PMCID: PMC5154959 DOI: 10.1002/adhm.201600415] [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: 04/12/2016] [Revised: 06/22/2016] [Indexed: 11/09/2022]
Abstract
Traumatic spinal cord injuries ultimately result in an inhibitory environment that prevents axonal regeneration from occurring. A low concentration administration of paclitaxel has been previously shown to promote axonal extension and attenuate the upregulation of inhibitory molecules after a spinal cord injury. In this study, paclitaxel is incorporated into electrospun poly(l-lactic acid) (PLA) microfibers, and it is established that a local release of paclitaxel from aligned, electrospun microfibers promotes neurite extension in a growth-conducive and inhibitory environment. Isolated dorsal root ganglion cells are cultured for 5 d directly on tissue culture polystyrene surface, PLA film, random, or aligned electrospun PLA microfibers (1.44 ± 0.03 μm) with paclitaxel incorporated at various concentrations (0%-5.0% w/w in reference to fiber weight). To determine the effect of a local release of paclitaxel, paclitaxel-loaded microfibers are placed in CellCrown inserts above cultured neurons. Average neurite extension rate is quantified for each sample. A local release of paclitaxel maintains neuronal survival and neurite extension in a concentration-dependent manner when coupled with aligned microfibers when cultured on laminin or an inhibitory surface of aggrecan. The findings provide a targeted approach to improve axonal extension across the inhibitory environment present after a traumatic injury in the spinal cord.
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Affiliation(s)
- Jose A Roman
- Department of Biomedical Engineering, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD, 21205, USA
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, 400 N. Broadway, Baltimore, MD, 21231, USA
- Institute for NanoBioTechnology, Johns Hopkins University, 3400 N Charles St, 100 Croft Hall, Baltimore, MD, 21218, USA
| | - Ian Reucroft
- Institute for NanoBioTechnology, Johns Hopkins University, 3400 N Charles St, 100 Croft Hall, Baltimore, MD, 21218, USA
| | - Russell A Martin
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, 400 N. Broadway, Baltimore, MD, 21231, USA
- Institute for NanoBioTechnology, Johns Hopkins University, 3400 N Charles St, 100 Croft Hall, Baltimore, MD, 21218, USA
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 N Charles St, Maryland Hall 206, Baltimore, MD, 21218, USA
| | - Andres Hurtado
- Department of Neurology, Johns Hopkins University School of Medicine, 1800 Orleans St, Baltimore, MD, 21287, USA
| | - Hai-Quan Mao
- Translational Tissue Engineering Center, Johns Hopkins University School of Medicine, 400 N. Broadway, Baltimore, MD, 21231, USA.
- Institute for NanoBioTechnology, Johns Hopkins University, 3400 N Charles St, 100 Croft Hall, Baltimore, MD, 21218, USA.
- Department of Materials Science and Engineering, Johns Hopkins University, 3400 N Charles St, Maryland Hall 206, Baltimore, MD, 21218, USA.
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215
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Chia JX, Efimova N, Svitkina TM. Neurite outgrowth is driven by actin polymerization even in the presence of actin polymerization inhibitors. Mol Biol Cell 2016; 27:mbc.E16-04-0253. [PMID: 27682586 PMCID: PMC5170553 DOI: 10.1091/mbc.e16-04-0253] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 09/19/2016] [Accepted: 09/20/2016] [Indexed: 12/20/2022] Open
Abstract
Actin polymerization is a universal mechanism to drive plasma membrane protrusion in motile cells. One apparent exception to this rule is continuing, or even accelerated outgrowth of neuronal processes in the presence of actin polymerization inhibitors. This fact together with a key role of microtubule dynamics in neurite outgrowth led to the concept that microtubules directly drive plasma membrane protrusion, either in the course of polymerization or motor-driven sliding. Surprisingly, a possibility that unextinguished actin polymerization drives neurite outgrowth in the presence of actin drugs was not explored. We show that cultured hippocampal neurons treated with cytochalasin D or latrunculin B contained dense accumulations of branched actin filaments at ∼50% of neurite tips at all tested drug concentrations (1-10 μM). Actin polymerization was required for neurite outgrowth, because only low concentrations of either inhibitor increased the length and/or a number of neurites, whereas high concentrations inhibited neurite outgrowth. Importantly, neurites undergoing active elongation invariably contained a bright F-actin patch at the tip, whereas actin-depleted neurites never elongated, even though they still contained dynamic microtubules. Stabilization of microtubules by taxol treatment did not stop elongation of cytochalasin d-treated neurites. We conclude that actin polymerization is indispensable for neurite elongation.
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Affiliation(s)
- Jonathan X Chia
- Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, PA 19104
| | - Nadia Efimova
- Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, PA 19104
| | - Tatyana M Svitkina
- Department of Biology, University of Pennsylvania, 433 S. University Avenue, Philadelphia, PA 19104
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216
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Abstract
Environmental insult, disease or trauma can affect the physical integrity of neuronal circuits, and the inability of many neurons to regenerate injured axons invariably leads to irreversible neural dysfunction. The conserved second messenger cyclic adenosine monophosphate (cAMP) can promote axonal re-growth. Widely used pharmacological or genetic approaches to increase intracellular levels of cAMP are often inadequate for precise neural-circuit reconstruction because their activity cannot be easily timed to specific target cells. These shortcomings have prevented the controlled repair of pre-defined neurons at selected time points in whole specimens. Thus, technologies to guide neuronal repair in time and space would enable studies of neural-circuit recovery with unprecedented resolution. Towards this aim, we have implemented a proof-of-principle optogenetic method to promote the selective regeneration of refractory axons in a living vertebrate.
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Affiliation(s)
- Yan Xiao
- Helmholtz Zentrum München, Munich, Germany
| | - Weili Tian
- Helmholtz Zentrum München, Munich, Germany
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217
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Abstract
Tissue growth and regeneration are autonomous, stem-cell-mediated processes in which stem cells within the organ self-renew and differentiate to create new cells, leading to new tissue. The processes of growth and regeneration require communication and interplay between neighboring cells. In particular, cell competition, which is a process in which viable cells are actively eliminated by more competitive cells, has been increasingly implicated to play an important role. Here, we discuss the existing literature regarding the current landscape of cell competition, including classical pathways and models, fitness fingerprint mechanisms, and immune system mechanisms of cell competition. We further discuss the clinical relevance of cell competition in the physiological processes of tissue growth and regeneration, highlighting studies in clinically important disease models, including oncological, neurological, and cardiovascular diseases.
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Affiliation(s)
- Rajan Gogna
- Institut für Zellbiologie, University of Bern, CH-3012 Bern, Switzerland; .,Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, New Hampshire 03766
| | - Kevin Shee
- Department of Radiology, Geisel School of Medicine at Dartmouth, Dartmouth College, Hanover, New Hampshire 03766
| | - Eduardo Moreno
- Institut für Zellbiologie, University of Bern, CH-3012 Bern, Switzerland;
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218
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Voelzmann A, Hahn I, Pearce SP, Sánchez-Soriano N, Prokop A. A conceptual view at microtubule plus end dynamics in neuronal axons. Brain Res Bull 2016; 126:226-237. [PMID: 27530065 PMCID: PMC5090033 DOI: 10.1016/j.brainresbull.2016.08.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 12/02/2022]
Abstract
Axons are the cable-like protrusions of neurons which wire up the nervous system. Polar bundles of microtubules (MTs) constitute their structural backbones and are highways for life-sustaining transport between proximal cell bodies and distal synapses. Any morphogenetic changes of axons during development, plastic rearrangement, regeneration or degeneration depend on dynamic changes of these MT bundles. A key mechanism for implementing such changes is the coordinated polymerisation and depolymerisation at the plus ends of MTs within these bundles. To gain an understanding of how such regulation can be achieved at the cellular level, we provide here an integrated overview of the extensive knowledge we have about the molecular mechanisms regulating MT de/polymerisation. We first summarise insights gained from work in vitro, then describe the machinery which supplies the essential tubulin building blocks, the protein complexes associating with MT plus ends, and MT shaft-based mechanisms that influence plus end dynamics. We briefly summarise the contribution of MT plus end dynamics to important cellular functions in axons, and conclude by discussing the challenges and potential strategies of integrating the existing molecular knowledge into conceptual understanding at the level of axons.
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Affiliation(s)
- André Voelzmann
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Ines Hahn
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK
| | - Simon P Pearce
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK; The University of Manchester, School of Mathematics, Alan Turing Building, Oxford Road, Manchester M13 9PL, UK
| | - Natalia Sánchez-Soriano
- University of Liverpool, Institute of Translational Medicine, Department of Cellular and Molecular Physiology, Crown Street, Liverpool, L69 3BX, UK
| | - Andreas Prokop
- The University of Manchester, Faculty of Biology, Medicine and Health, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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219
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Baas PW, Rao AN, Matamoros AJ, Leo L. Stability properties of neuronal microtubules. Cytoskeleton (Hoboken) 2016; 73:442-60. [PMID: 26887570 PMCID: PMC5541393 DOI: 10.1002/cm.21286] [Citation(s) in RCA: 184] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/02/2016] [Accepted: 02/12/2016] [Indexed: 01/12/2023]
Abstract
Neurons are terminally differentiated cells that use their microtubule arrays not for cell division but rather as architectural elements required for the elaboration of elongated axons and dendrites. In addition to acting as compression-bearing struts that provide for the shape of the neuron, microtubules also act as directional railways for organelle transport. The stability properties of neuronal microtubules are commonly discussed in the biomedical literature as crucial to the development and maintenance of the nervous system, and have recently gained attention as central to the etiology of neurodegenerative diseases. Drugs that affect microtubule stability are currently under investigation as potential therapies for disease and injury of the nervous system. There is often a lack of consistency, however, in how the issue of microtubule stability is discussed in the literature, and this can affect the design and interpretation of experiments as well as potential therapeutic regimens. Neuronal microtubules are considered to be more stable than microtubules in dividing cells. On average, this is true, but in addition to an abundant stable microtubule fraction in neurons, there is also an abundant labile microtubule fraction. Both are functionally important. Individual microtubules consist of domains that differ in their stability properties, and these domains can also differ markedly in their composition as well as how they interact with various microtubule-related proteins in the neuron. Myriad proteins and pathways have been discussed as potential contributors to microtubule stability in neurons. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
| | - Anand N Rao
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Andrew J Matamoros
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Lanfranco Leo
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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220
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Galiano MR, Goitea VE, Hallak ME. Post-translational protein arginylation in the normal nervous system and in neurodegeneration. J Neurochem 2016; 138:506-17. [PMID: 27318192 DOI: 10.1111/jnc.13708] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 05/24/2016] [Accepted: 06/13/2016] [Indexed: 02/07/2023]
Abstract
Post-translational arginylation of proteins is an important regulator of many physiological pathways in cells. This modification was originally noted in protein degradation during neurodegenerative processes, with an apparently different physiological relevance between central and peripheral nervous system. Subsequent studies have identified a steadily increasing number of proteins and proteolysis-derived polypeptides as arginyltransferase (ATE1) substrates, including β-amyloid, α-synuclein, and TDP43 proteolytic fragments. Arginylation is involved in signaling processes of proteins and polypeptides that are further ubiquitinated and degraded by the proteasome. In addition, it is also implicated in autophagy/lysosomal degradation pathway. Recent studies using mutant mouse strains deficient in ATE1 indicate additional roles of this modification in neuronal physiology. As ATE1 is capable of modifying proteins either at the N-terminus or middle-chain acidic residues, determining which proteins function are modulated by arginylation represents a big challenge. Here, we review studies addressing various roles of ATE1 activity in nervous system function, and suggest future research directions that will clarify the role of post-translational protein arginylation in brain development and various neurological disorders. Arginyltransferase (ATE1), the enzyme responsible for post-translational arginylation, modulates the functions of a wide variety of proteins and polypeptides, and is also involved in the main degradation pathways of intracellular proteins. Regulatory roles of ATE1 have been well defined for certain organs. However, its roles in nervous system development and neurodegenerative processes remain largely unknown, and present exciting opportunities for future research, as discussed in this review.
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Affiliation(s)
- Mauricio R Galiano
- Centro de Investigaciones de Química Biológica de Córdoba, CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina
| | - Victor E Goitea
- Centro de Investigaciones de Química Biológica de Córdoba, CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina
| | - Marta E Hallak
- Centro de Investigaciones de Química Biológica de Córdoba, CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, CONICET, Universidad Nacional de Córdoba, Ciudad Universitaria, Córdoba, Argentina
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221
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Spitzbarth I, Lempp C, Kegler K, Ulrich R, Kalkuhl A, Deschl U, Baumgärtner W, Seehusen F. Immunohistochemical and transcriptome analyses indicate complex breakdown of axonal transport mechanisms in canine distemper leukoencephalitis. Brain Behav 2016; 6:e00472. [PMID: 27247850 PMCID: PMC4864272 DOI: 10.1002/brb3.472] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 02/24/2016] [Accepted: 03/11/2016] [Indexed: 12/03/2022] Open
Abstract
INTRODUCTION CDV-DL (Canine distemper virus-induced demyelinating leukoencephalitis) represents a spontaneously occurring animal model for demyelinating disorders. Axonopathy represents a key pathomechanism in this disease; however, its underlying pathogenesis has not been addressed in detail so far. This study aimed at the characterization of axonal cytoskeletal, transport, and potential regenerative changes with a parallel focus upon Schwann cell remyelination. METHODS Immunohistochemistry of canine cerebellar tissue as well as a comparative analysis of genes from an independent microarray study were performed. RESULTS Increased axonal immunoreactivity for nonphosphorylated neurofilament was followed by loss of cytoskeletal and motor proteins. Interestingly, a subset of genes encoding for neurofilament subunits and motor proteins was up-regulated in the chronic stage compared to dogs with subacute CDV-DL. However, immunohistochemically, hints for axonal regeneration were restricted to up-regulated axonal positivity of hypoxia-inducible factor 1 alpha, while growth-associated protein 43, erythropoietin and its receptor were not or even down-regulated. Periaxin-positive structures, indicative of Schwann cell remyelination, were only detected within few advanced lesions. CONCLUSIONS The present findings demonstrate a complex sequence of axonal cytoskeletal breakdown mechanisms. Moreover, though sparse, this is the first report of Schwann cell remyelination in CDV-DL. Facilitation of these very limited endogenous regenerative responses represents an important topic for future research.
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Affiliation(s)
- Ingo Spitzbarth
- Department of Pathology University of Veterinary Medicine Hannover Foundation Bünteweg 17 30559 Hannover Germany; Center for Systems Neuroscience Bünteweg 2 30559 Hannover Germany
| | - Charlotte Lempp
- Department of Pathology University of Veterinary Medicine Hannover Foundation Bünteweg 17 30559 Hannover Germany
| | - Kristel Kegler
- Department of Pathology University of Veterinary Medicine Hannover Foundation Bünteweg 17 30559 Hannover Germany; Center for Systems Neuroscience Bünteweg 2 30559 Hannover Germany
| | - Reiner Ulrich
- Department of Pathology University of Veterinary Medicine Hannover Foundation Bünteweg 17 30559 Hannover Germany; Center for Systems Neuroscience Bünteweg 2 30559 Hannover Germany
| | - Arno Kalkuhl
- Department of Non-Clinical Drug Safety Boehringer Ingelheim Pharma GmbH & Co KG Biberach (Riß) Germany
| | - Ulrich Deschl
- Department of Non-Clinical Drug Safety Boehringer Ingelheim Pharma GmbH & Co KG Biberach (Riß) Germany
| | - Wolfgang Baumgärtner
- Department of Pathology University of Veterinary Medicine Hannover Foundation Bünteweg 17 30559 Hannover Germany; Center for Systems Neuroscience Bünteweg 2 30559 Hannover Germany
| | - Frauke Seehusen
- Department of Pathology University of Veterinary Medicine Hannover Foundation Bünteweg 17 30559 Hannover Germany
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222
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Kiryu-Seo S, Tamada H, Kato Y, Yasuda K, Ishihara N, Nomura M, Mihara K, Kiyama H. Mitochondrial fission is an acute and adaptive response in injured motor neurons. Sci Rep 2016; 6:28331. [PMID: 27319806 PMCID: PMC4913268 DOI: 10.1038/srep28331] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 06/02/2016] [Indexed: 12/03/2022] Open
Abstract
Successful recovery from neuronal damage requires a huge energy supply, which is provided by mitochondria. However, the physiological relevance of mitochondrial dynamics in damaged neurons in vivo is poorly understood. To address this issue, we established unique bacterial artificial chromosome transgenic (BAC Tg) mice, which develop and function normally, but in which neuronal injury induces labelling of mitochondria with green fluorescent protein (GFP) and expression of cre recombinase. GFP-labelled mitochondria in BAC Tg mice appear shorter in regenerating motor axons soon after nerve injury compared with mitochondria in non-injured axons, suggesting the importance of increased mitochondrial fission during the early phase of nerve regeneration. Crossing the BAC Tg mice with mice carrying a floxed dynamin-related protein 1 gene (Drp1), which is necessary for mitochondrial fission, ablates mitochondrial fission specifically in injured neurons. Injury-induced Drp1-deficient motor neurons show elongated or abnormally gigantic mitochondria, which have impaired membrane potential and axonal transport velocity during the early phase after injury, and eventually promote neuronal death. Our in vivo data suggest that acute and prominent mitochondrial fission during the early stage after nerve injury is an adaptive response and is involved in the maintenance of mitochondrial and neuronal integrity to prevent neurodegeneration.
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Affiliation(s)
- Sumiko Kiryu-Seo
- Department of Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.,CREST, JST, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Hiromi Tamada
- Department of Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Yukina Kato
- Department of Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Katsura Yasuda
- Department of Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
| | - Naotada Ishihara
- Department of Protein Biochemistry, Institute of Life Science, Kurume University, Kurume 839-0864, Japan
| | - Masatoshi Nomura
- Department of Medicine and Bioregulatory Science, Graduate School of Medical Science, Kyushu University,Fukuoka 812-8382, Japan
| | - Katsuyoshi Mihara
- Department of Molecular Biology, Graduate School of Medical Science, Kyushu University, Fukuoka 812-8382, Japan
| | - Hiroshi Kiyama
- Department of Functional Anatomy and Neuroscience, Graduate School of Medicine, Nagoya University, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan.,CREST, JST, 65 Tsurumai-cho, Showa-ku, Nagoya 466-8550, Japan
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223
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Zhou B, Yu P, Lin MY, Sun T, Chen Y, Sheng ZH. Facilitation of axon regeneration by enhancing mitochondrial transport and rescuing energy deficits. J Cell Biol 2016; 214:103-19. [PMID: 27268498 PMCID: PMC4932375 DOI: 10.1083/jcb.201605101] [Citation(s) in RCA: 212] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 05/31/2016] [Indexed: 11/22/2022] Open
Abstract
Zhou et al. show that reduced mitochondrial motility and energy deficits in injured axons are intrinsic mechanisms contributing to regeneration failure in mature neurons. Although neuronal regeneration is a highly energy-demanding process, axonal mitochondrial transport progressively declines with maturation. Mature neurons typically fail to regenerate after injury, thus raising a fundamental question as to whether mitochondrial transport is necessary to meet enhanced metabolic requirements during regeneration. Here, we reveal that reduced mitochondrial motility and energy deficits in injured axons are intrinsic mechanisms controlling regrowth in mature neurons. Axotomy induces acute mitochondrial depolarization and ATP depletion in injured axons. Thus, mature neuron-associated increases in mitochondria-anchoring protein syntaphilin (SNPH) and decreases in mitochondrial transport cause local energy deficits. Strikingly, enhancing mitochondrial transport via genetic manipulation facilitates regenerative capacity by replenishing healthy mitochondria in injured axons, thereby rescuing energy deficits. An in vivo sciatic nerve crush study further shows that enhanced mitochondrial transport in snph knockout mice accelerates axon regeneration. Understanding deficits in mitochondrial trafficking and energy supply in injured axons of mature neurons benefits development of new strategies to stimulate axon regeneration.
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Affiliation(s)
- Bing Zhou
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Panpan Yu
- Guangdong-Hong Kong-Macau Institute of CNS Regeneration, Ministry of Education Joint International Research Laboratory of CNS Regeneration, Jinan University, Guangzhou 510632, China
| | - Mei-Yao Lin
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Tao Sun
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Yanmin Chen
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
| | - Zu-Hang Sheng
- Synaptic Functions Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892
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224
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Liu Y, Kelamangalath L, Kim H, Han SB, Tang X, Zhai J, Hong JW, Lin S, Son YJ, Smith GM. NT-3 promotes proprioceptive axon regeneration when combined with activation of the mTor intrinsic growth pathway but not with reduction of myelin extrinsic inhibitors. Exp Neurol 2016; 283:73-84. [PMID: 27264357 DOI: 10.1016/j.expneurol.2016.05.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 05/13/2016] [Accepted: 05/17/2016] [Indexed: 11/25/2022]
Abstract
Although previous studies have identified several strategies to stimulate regeneration of CNS axons, extensive regeneration and functional recovery have remained a major challenge, particularly for large diameter myelinated axons. Within the CNS, myelin is thought to inhibit axon regeneration, while modulating activity of the mTOR pathway promotes regeneration of injured axons. In this study, we examined NT-3 mediated regeneration of sensory axons through the dorsal root entry zone in a triple knockout of myelin inhibitory proteins or after activation of mTOR using a constitutively active (ca) Rheb in DRG neurons to determine the influence of environmental inhibitory or activation of intrinsic growth pathways could enhance NT-3-mediate regeneration. Loss of myelin inhibitory proteins showed modest enhancement of sensory axon regeneration. In mTOR studies, we found a dramatic age related decrease in the mTOR activation as determined by phosphorylation of the downstream marker S6 ribosomal subunit. Expression of caRheb within adult DRG neurons in vitro increased S6 phosphorylation and doubled the overall length of neurite outgrowth, which was reversed in the presence of rapamycin. In adult female rats, combined expression of caRheb in DRG neurons and NT-3 within the spinal cord increased regeneration of sensory axons almost 3 fold when compared to NT-3 alone. Proprioceptive assessment using a grid runway indicates functionally significant regeneration of large-diameter myelinated sensory afferents. Our results indicate that caRheb-induced increase in mTOR activation enhances neurotrophin-3 induced regeneration of large-diameter myelinated axons.
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Affiliation(s)
- Yingpeng Liu
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Lakshmi Kelamangalath
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Hyukmin Kim
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Seung Baek Han
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Xiaoqing Tang
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jinbin Zhai
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Jee W Hong
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Shen Lin
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Young-Jin Son
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - George M Smith
- Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA.
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225
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Abstract
CNS injury may lead to permanent functional deficits because it is still not possible to regenerate axons over long distances and accurately reconnect them with an appropriate target. Using rat neurons, microtools, and nanotools, we show that new, functional neurites can be created and precisely positioned to directly (re)wire neuronal networks. We show that an adhesive contact made onto an axon or dendrite can be pulled to initiate a new neurite that can be mechanically guided to form new synapses at up to 0.8 mm distance in <1 h. Our findings challenge current understanding of the limits of neuronal growth and have direct implications for the development of new therapies and surgical techniques to achieve functional regeneration. Significance statement: Brain and spinal cord injury may lead to permanent disability and death because it is still not possible to regenerate neurons over long distances and accurately reconnect them with an appropriate target. Using microtools and nanotools we have developed a new method to rapidly initiate, elongate, and precisely connect new functional neuronal circuits over long distances. The extension rates achieved are ≥60 times faster than previously reported. Our findings have direct implications for the development of new therapies and surgical techniques to achieve functional regeneration after trauma and in neurodegenerative diseases. It also opens the door for the direct wiring of robust brain-machine interfaces as well as for investigations of fundamental aspects of neuronal signal processing and neuronal function.
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226
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Vogelaar CF. Extrinsic and intrinsic mechanisms of axon regeneration: the need for spinal cord injury treatment strategies to address both. Neural Regen Res 2016; 11:572-4. [PMID: 27212916 PMCID: PMC4870912 DOI: 10.4103/1673-5374.180740] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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227
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He Z, Jin Y. Intrinsic Control of Axon Regeneration. Neuron 2016; 90:437-51. [DOI: 10.1016/j.neuron.2016.04.022] [Citation(s) in RCA: 337] [Impact Index Per Article: 42.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 03/10/2016] [Accepted: 04/13/2016] [Indexed: 01/12/2023]
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228
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Levine J. The reactions and role of NG2 glia in spinal cord injury. Brain Res 2016; 1638:199-208. [PMID: 26232070 PMCID: PMC4732922 DOI: 10.1016/j.brainres.2015.07.026] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 07/02/2015] [Accepted: 07/18/2015] [Indexed: 01/06/2023]
Abstract
Oligodendrocyte precursor cells (OPCs) react rapidly to brain and spinal cord injuries. This reaction is characterized by the retraction of cell processes, cell body swelling and increased expression of the NG2 chondroitin sulfate proteoglycan. Reactive OPCs rapidly divide and accumulate surrounding the injury site where they become major cellular components of the glial scar. The glial reaction to injury is an attempt to restore normal homeostasis and re-establish the glia limitans but the exact role of reactive OPCs in these processes is not well understood. Traumatic injury results in extensive oligodendrocyte cell death and the proliferating OPCs generate the large number of precursor cells necessary for remyelination. Reactive OPCs, however, also are a source of axon-growth inhibitory proteoglycans and may interact with invading inflammatory cells in complex ways. Here, I discuss these and other properties of OPCs after spinal cord injury. Understanding the regulation of these disparate properties may lead to new therapeutic approaches to devastating injuries of the spinal cord. This article is part of a Special Issue entitled SI:NG2-glia(Invited only).
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Affiliation(s)
- Joel Levine
- Department of Neurobiology and Behavior, Stonybrook University, Stony Brook, NY 11794, USA.
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229
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Abstract
The capacity of an axon to regenerate is regulated by its external environment and by cell-intrinsic factors. Studies in a variety of organisms suggest that alterations in axonal microtubule (MT) dynamics have potent effects on axon regeneration. We review recent findings on the regulation of MT dynamics during axon regeneration, focusing on the nematode Caenorhabditis elegans. In C. elegans the dual leucine zipper kinase (DLK) promotes axon regeneration, whereas the exchange factor for Arf6 (EFA-6) inhibits axon regeneration. Both DLK and EFA-6 respond to injury and control axon regeneration in part via MT dynamics. How the DLK and EFA-6 pathways are related is a topic of active investigation, as is the mechanism by which EFA-6 responds to axonal injury. We evaluate potential candidates, such as the MT affinity-regulating kinase PAR-1/MARK, in regulation of EFA-6 and axonal MT dynamics in regeneration.
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Affiliation(s)
- Ngang Heok Tang
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Andrew D Chisholm
- Section of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
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230
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Jing Z, Yin H, Wang P, Gao J, Yuan L. Centlein, a novel microtubule-associated protein stabilizing microtubules and involved in neurite formation. Biochem Biophys Res Commun 2016; 472:360-5. [DOI: 10.1016/j.bbrc.2016.02.079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 02/19/2016] [Indexed: 11/24/2022]
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231
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Jessen KR, Mirsky R. The repair Schwann cell and its function in regenerating nerves. J Physiol 2016; 594:3521-31. [PMID: 26864683 PMCID: PMC4929314 DOI: 10.1113/jp270874] [Citation(s) in RCA: 703] [Impact Index Per Article: 87.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Accepted: 11/28/2015] [Indexed: 01/05/2023] Open
Abstract
Nerve injury triggers the conversion of myelin and non‐myelin (Remak) Schwann cells to a cell phenotype specialized to promote repair. Distal to damage, these repair Schwann cells provide the necessary signals and spatial cues for the survival of injured neurons, axonal regeneration and target reinnervation. The conversion to repair Schwann cells involves de‐differentiation together with alternative differentiation, or activation, a combination that is typical of cell type conversions often referred to as (direct or lineage) reprogramming. Thus, injury‐induced Schwann cell reprogramming involves down‐regulation of myelin genes combined with activation of a set of repair‐supportive features, including up‐regulation of trophic factors, elevation of cytokines as part of the innate immune response, myelin clearance by activation of myelin autophagy in Schwann cells and macrophage recruitment, and the formation of regeneration tracks, Bungner's bands, for directing axons to their targets. This repair programme is controlled transcriptionally by mechanisms involving the transcription factor c‐Jun, which is rapidly up‐regulated in Schwann cells after injury. In the absence of c‐Jun, damage results in the formation of a dysfunctional repair cell, neuronal death and failure of functional recovery. c‐Jun, although not required for Schwann cell development, is therefore central to the reprogramming of myelin and non‐myelin (Remak) Schwann cells to repair cells after injury. In future, the signalling that specifies this cell requires further analysis so that pharmacological tools that boost and maintain the repair Schwann cell phenotype can be developed.
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Affiliation(s)
- K R Jessen
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - R Mirsky
- Department of Cell and Developmental Biology, University College London, Gower Street, London, WC1E 6BT, UK
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232
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Anastasiadou S, Knöll B. The multiple sclerosis drug fingolimod (FTY720) stimulates neuronal gene expression, axonal growth and regeneration. Exp Neurol 2016; 279:243-260. [PMID: 26980486 DOI: 10.1016/j.expneurol.2016.03.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 03/03/2016] [Accepted: 03/11/2016] [Indexed: 11/30/2022]
Abstract
Fingolimod (FTY720) is a new generation oral treatment for multiple sclerosis (MS). So far, FTY720 was mainly considered to target trafficking of immune cells but not brain cells such as neurons. Herein, we analyzed FTY720's potential to directly alter neuronal function. In CNS neurons, we identified a FTY720 governed gene expression response. FTY720 upregulated immediate early genes (IEGs) encoding for neuronal activity associated transcription factors such as c-Fos, FosB, Egr1 and Egr2 and induced actin cytoskeleton associated genes (actin isoforms, tropomyosin, calponin). Stimulation of primary neurons with FTY720 enhanced neurite growth and altered growth cone morphology. In accordance, FTY720 enhanced axon regeneration in mice upon facial nerve axotomy. We identified components of a FTY720 engaged signaling cascade including S1P receptors, G12/13G-proteins, RhoA-GTPases and the transcription factors SRF/MRTF. In summary, we uncovered a broader cellular and therapeutic operation mode of FTY720, suggesting beneficial FTY720 effects also on CNS neurons during MS therapy and for treatment of other neurodegenerative diseases requiring neuroprotective and neurorestorative processes.
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Affiliation(s)
- Sofia Anastasiadou
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Bernd Knöll
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
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233
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Soloperto A, Palazzolo G, Tsushima H, Chieregatti E, Vassalli M, Difato F. Laser Nano-Neurosurgery from Gentle Manipulation to Nano-Incision of Neuronal Cells and Scaffolds: An Advanced Neurotechnology Tool. Front Neurosci 2016; 10:101. [PMID: 27013962 PMCID: PMC4786546 DOI: 10.3389/fnins.2016.00101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 02/26/2016] [Indexed: 11/13/2022] Open
Abstract
Current optical approaches are progressing far beyond the scope of monitoring the structure and function of living matter, and they are becoming widely recognized as extremely precise, minimally-invasive, contact-free handling tools. Laser manipulation of living tissues, single cells, or even single-molecules is becoming a well-established methodology, thus founding the onset of new experimental paradigms and research fields. Indeed, a tightly focused pulsed laser source permits complex tasks such as developing engineered bioscaffolds, applying calibrated forces, transfecting, stimulating, or even ablating single cells with subcellular precision, and operating intracellular surgical protocols at the level of single organelles. In the present review, we report the state of the art of laser manipulation in neuroscience, to inspire future applications of light-assisted tools in nano-neurosurgery.
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Affiliation(s)
- Alessandro Soloperto
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Gemma Palazzolo
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Hanako Tsushima
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Evelina Chieregatti
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia Genoa, Italy
| | - Massimo Vassalli
- Institute of Biophysics, National Research Council of Italy Genoa, Italy
| | - Francesco Difato
- Neuroscience and Brain Technologies Department, Istituto Italiano di Tecnologia Genoa, Italy
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234
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Promoting axon regeneration in the adult CNS by modulation of the melanopsin/GPCR signaling. Proc Natl Acad Sci U S A 2016; 113:1937-42. [PMID: 26831088 DOI: 10.1073/pnas.1523645113] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cell-type-specific G protein-coupled receptor (GPCR) signaling regulates distinct neuronal responses to various stimuli and is essential for axon guidance and targeting during development. However, its function in axonal regeneration in the mature CNS remains elusive. We found that subtypes of intrinsically photosensitive retinal ganglion cells (ipRGCs) in mice maintained high mammalian target of rapamycin (mTOR) levels after axotomy and that the light-sensitive GPCR melanopsin mediated this sustained expression. Melanopsin overexpression in the RGCs stimulated axonal regeneration after optic nerve crush by up-regulating mTOR complex 1 (mTORC1). The extent of the regeneration was comparable to that observed after phosphatase and tensin homolog (Pten) knockdown. Both the axon regeneration and mTOR activity that were enhanced by melanopsin required light stimulation and Gq/11 signaling. Specifically, activating Gq in RGCs elevated mTOR activation and promoted axonal regeneration. Melanopsin overexpression in RGCs enhanced the amplitude and duration of their light response, and silencing them with Kir2.1 significantly suppressed the increased mTOR signaling and axon regeneration that were induced by melanopsin. Thus, our results provide a strategy to promote axon regeneration after CNS injury by modulating neuronal activity through GPCR signaling.
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235
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Rozés Salvador V, Heredia F, Berardo A, Palandri A, Wojnacki J, Vivinetto AL, Sheikh KA, Caceres A, Lopez PHH. Anti-glycan antibodies halt axon regeneration in a model of Guillain Barrè Syndrome axonal neuropathy by inducing microtubule disorganization via RhoA-ROCK-dependent inactivation of CRMP-2. Exp Neurol 2016; 278:42-53. [PMID: 26804001 DOI: 10.1016/j.expneurol.2016.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 01/19/2016] [Indexed: 10/22/2022]
Abstract
Several reports have linked the presence of high titers of anti-Gg Abs with delayed recovery/poor prognosis in GBS. In most cases, failure to recover is associated with halted/deficient axon regeneration. Previous work identified that monoclonal and patient-derived anti-Gg Abs can act as inhibitory factors in an animal model of axon regeneration. Further studies using primary dorsal root ganglion neuron (DRGn) cultures demonstrated that anti-Gg Abs can inhibit neurite outgrowth by targeting gangliosides via activation of the small GTPase RhoA and its associated kinase (ROCK), a signaling pathway common to other established inhibitors of axon regeneration. We aimed to study the molecular basis of the inhibitory effect of anti-Gg abs on neurite outgrowth by dissecting the molecular dynamics of growth cones (GC) cytoskeleton in relation to the spatial-temporal analysis of RhoA activity. We now report that axon growth inhibition in DRGn induced by a well characterized mAb targeting gangliosides GD1a/GT1b involves: i) an early RhoA/ROCK-independent collapse of lamellipodia; ii) a RhoA/ROCK-dependent shrinking of filopodia; and iii) alteration of GC microtubule organization/and presumably dynamics via RhoA/ROCK-dependent phosphorylation of CRMP-2 at threonine 555. Our results also show that mAb 1B7 inhibits peripheral axon regeneration in an animal model via phosphorylation/inactivation of CRMP-2 at threonine 555. Overall, our data may help to explain the molecular mechanisms underlying impaired nerve repair in GBS. Future work should define RhoA-independent pathway/s and effectors regulating actin cytoskeleton, thus providing an opportunity for the design of a successful therapy to guarantee an efficient target reinnervation.
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Affiliation(s)
- Victoria Rozés Salvador
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Florencia Heredia
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Andrés Berardo
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Anabela Palandri
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Jose Wojnacki
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Ana L Vivinetto
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Kazim A Sheikh
- Department of Neurology, University of Texas Medical School at Houston, Houston, USA
| | - Alfredo Caceres
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina
| | - Pablo H H Lopez
- Laboratory of Neurobiology, Instituto de Investigación Médica Mercedes y Martin Ferreyra, INIMEC-CONICET-Universidad Nacional de Córdoba, Argentina; Facultad de Psicología, Universidad Nacional de Córdoba, Argentina.
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236
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Live imaging of microtubule dynamics in organotypic hippocampal slice cultures. Methods Cell Biol 2016; 131:107-26. [DOI: 10.1016/bs.mcb.2015.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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237
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Intrinsic Neuronal Mechanisms in Axon Regeneration After Spinal Cord Injury. Transl Neurosci 2016. [DOI: 10.1007/978-1-4899-7654-3_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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238
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Abstract
Heterogeneous and unpredictable environmental insult, disease, or trauma can affect the integrity and function of neuronal circuits, leading to irreversible neural dysfunction. The peripheral nervous system can robustly regenerate axons after damage to recover the capacity to transmit sensory information to the brain. The mechanisms that allow axonal repair remain incompletely understood. Here we present a preparation in zebrafish that combines laser microsurgery of sensory axons and videomicroscopy of neurons in multicolor transgenic specimens. This simple protocol allows controlled damage of axons and dynamic high-resolution visualization and quantification of repair.
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239
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van Niekerk EA, Tuszynski MH, Lu P, Dulin JN. Molecular and Cellular Mechanisms of Axonal Regeneration After Spinal Cord Injury. Mol Cell Proteomics 2015; 15:394-408. [PMID: 26695766 DOI: 10.1074/mcp.r115.053751] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 12/28/2022] Open
Abstract
Following axotomy, a complex temporal and spatial coordination of molecular events enables regeneration of the peripheral nerve. In contrast, multiple intrinsic and extrinsic factors contribute to the general failure of axonal regeneration in the central nervous system. In this review, we examine the current understanding of differences in protein expression and post-translational modifications, activation of signaling networks, and environmental cues that may underlie the divergent regenerative capacity of central and peripheral axons. We also highlight key experimental strategies to enhance axonal regeneration via modulation of intraneuronal signaling networks and the extracellular milieu. Finally, we explore potential applications of proteomics to fill gaps in the current understanding of molecular mechanisms underlying regeneration, and to provide insight into the development of more effective approaches to promote axonal regeneration following injury to the nervous system.
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Affiliation(s)
- Erna A van Niekerk
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093;
| | - Mark H Tuszynski
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093; §Veterans Administration Medical Center, San Diego, CA 92161
| | - Paul Lu
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093; §Veterans Administration Medical Center, San Diego, CA 92161
| | - Jennifer N Dulin
- From the ‡Department of Neurosciences, University of California, San Diego, La Jolla, CA, 92093
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240
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Jenkins PM, Laughter MR, Lee DJ, Lee YM, Freed CR, Park D. A nerve guidance conduit with topographical and biochemical cues: potential application using human neural stem cells. NANOSCALE RESEARCH LETTERS 2015; 10:972. [PMID: 26071111 PMCID: PMC4469602 DOI: 10.1186/s11671-015-0972-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 06/03/2015] [Indexed: 05/26/2023]
Abstract
Despite major advances in the pathophysiological understanding of peripheral nerve damage, the treatment of nerve injuries still remains an unmet medical need. Nerve guidance conduits present a promising treatment option by providing a growth-permissive environment that 1) promotes neuronal cell survival and axon growth and 2) directs axonal extension. To this end, we designed an electrospun nerve guidance conduit using a blend of polyurea and poly-caprolactone with both biochemical and topographical cues. Biochemical cues were integrated into the conduit by functionalizing the polyurea with RGD to improve cell attachment. Topographical cues that resemble natural nerve tissue were incorporated by introducing intraluminal microchannels aligned with nanofibers. We determined that electrospinning the polymer solution across a two electrode system with dissolvable sucrose fibers produced a polymer conduit with the appropriate biomimetic properties. Human neural stem cells were cultured on the conduit to evaluate its ability to promote neuronal growth and axonal extension. The nerve guidance conduit was shown to enhance cell survival, migration, and guide neurite extension.
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Affiliation(s)
- Phillip M Jenkins
- />Department of Bioengineering, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Avenue, Aurora, CO 80045 USA
| | - Melissa R Laughter
- />Department of Bioengineering, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Avenue, Aurora, CO 80045 USA
| | - David J Lee
- />Department of Bioengineering, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Avenue, Aurora, CO 80045 USA
| | - Young M Lee
- />Division of Clinical Pharmacology and Toxicology, University of Colorado School of Medicine, 12700 E. 19th Avenue, Aurora, CO 80045 USA
| | - Curt R Freed
- />Division of Clinical Pharmacology and Toxicology, University of Colorado School of Medicine, 12700 E. 19th Avenue, Aurora, CO 80045 USA
| | - Daewon Park
- />Department of Bioengineering, University of Colorado Denver Anschutz Medical Campus, 12800 E. 19th Avenue, Aurora, CO 80045 USA
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241
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van Beuningen S, Will L, Harterink M, Chazeau A, van Battum E, Frias C, Franker M, Katrukha E, Stucchi R, Vocking K, Antunes A, Slenders L, Doulkeridou S, Sillevis Smitt P, Altelaar A, Post J, Akhmanova A, Pasterkamp R, Kapitein L, de Graaff E, Hoogenraad C. TRIM46 Controls Neuronal Polarity and Axon Specification by Driving the Formation of Parallel Microtubule Arrays. Neuron 2015; 88:1208-1226. [DOI: 10.1016/j.neuron.2015.11.012] [Citation(s) in RCA: 114] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 09/13/2015] [Accepted: 11/03/2015] [Indexed: 02/08/2023]
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242
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Purine nucleosides in neuroregeneration and neuroprotection. Neuropharmacology 2015; 104:226-42. [PMID: 26577017 DOI: 10.1016/j.neuropharm.2015.11.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 11/05/2015] [Accepted: 11/06/2015] [Indexed: 12/20/2022]
Abstract
In the present review, we stress the importance of the purine nucleosides, adenosine and guanosine, in protecting the nervous system, both centrally and peripherally, via activation of their receptors and intracellular signalling mechanisms. A most novel part of the review focus on the mechanisms of neuronal regeneration that are targeted by nucleosides, including a recently identified action of adenosine on axonal growth and microtubule dynamics. Discussion on the role of the purine nucleosides transversally with the most established neurotrophic factors, e.g. brain derived neurotrophic factor (BDNF), glial derived neurotrophic factor (GDNF), is also focused considering the intimate relationship between some adenosine receptors, as is the case of the A2A receptors, and receptors for neurotrophins. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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243
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Cho Y, Shin JE, Ewan EE, Oh YM, Pita-Thomas W, Cavalli V. Activating Injury-Responsive Genes with Hypoxia Enhances Axon Regeneration through Neuronal HIF-1α. Neuron 2015; 88:720-34. [PMID: 26526390 DOI: 10.1016/j.neuron.2015.09.050] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 08/24/2015] [Accepted: 09/22/2015] [Indexed: 02/07/2023]
Abstract
Injured peripheral neurons successfully activate a proregenerative transcriptional program to enable axon regeneration and functional recovery. How transcriptional regulators coordinate the expression of such program remains unclear. Here we show that hypoxia-inducible factor 1α (HIF-1α) controls multiple injury-induced genes in sensory neurons and contribute to the preconditioning lesion effect. Knockdown of HIF-1α in vitro or conditional knock out in vivo impairs sensory axon regeneration. The HIF-1α target gene Vascular Endothelial Growth Factor A (VEGFA) is expressed in injured neurons and contributes to stimulate axon regeneration. Induction of HIF-1α using hypoxia enhances axon regeneration in vitro and in vivo in sensory neurons. Hypoxia also stimulates motor neuron regeneration and accelerates neuromuscular junction re-innervation. This study demonstrates that HIF-1α represents a critical transcriptional regulator in regenerating neurons and suggests hypoxia as a tool to stimulate axon regeneration.
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Affiliation(s)
- Yongcheol Cho
- Department of Anatomy and Neurobiology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Jung Eun Shin
- Department of Developmental Biology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Eric Edward Ewan
- Department of Anatomy and Neurobiology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Young Mi Oh
- Department of Anatomy and Neurobiology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Wolfgang Pita-Thomas
- Department of Anatomy and Neurobiology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Valeria Cavalli
- Department of Anatomy and Neurobiology, School of Medicine, Washington University in St. Louis, St. Louis, MO 63110, USA.
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244
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Nawabi H, Belin S, Cartoni R, Williams PR, Wang C, Latremolière A, Wang X, Zhu J, Taub DG, Fu X, Yu B, Gu X, Woolf CJ, Liu JS, Gabel CV, Steen JA, He Z. Doublecortin-Like Kinases Promote Neuronal Survival and Induce Growth Cone Reformation via Distinct Mechanisms. Neuron 2015; 88:704-19. [PMID: 26526391 PMCID: PMC10069300 DOI: 10.1016/j.neuron.2015.10.005] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 06/04/2015] [Accepted: 09/30/2015] [Indexed: 01/15/2023]
Abstract
After axotomy, neuronal survival and growth cone re-formation are required for axon regeneration. We discovered that doublecortin-like kinases (DCLKs), members of the doublecortin (DCX) family expressed in adult retinal ganglion cells (RGCs), play critical roles in both processes, through distinct mechanisms. Overexpression of DCLK2 accelerated growth cone re-formation in vitro and enhanced the initiation and elongation of axon re-growth after optic nerve injury. These effects depended on both the microtubule (MT)-binding domain and the serine-proline-rich (S/P-rich) region of DCXs in-cis in the same molecules. While the MT-binding domain is known to stabilize MT structures, we show that the S/P-rich region prevents F-actin destabilization in injured axon stumps. Additionally, while DCXs synergize with mTOR to stimulate axon regeneration, alone they can promote neuronal survival possibly by regulating the retrograde propagation of injury signals. Multifunctional DCXs thus represent potential targets for promoting both survival and regeneration of injured neurons.
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Affiliation(s)
- Homaira Nawabi
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Stephane Belin
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Romain Cartoni
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Philip R Williams
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Chen Wang
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Alban Latremolière
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Xuhua Wang
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Junjie Zhu
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Daniel G Taub
- Departments of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Xiaoqin Fu
- Center for Neuroscience Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Bin Yu
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA; Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Xiaosong Gu
- Jiangsu Key Laboratory of Neuroregeneration, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Clifford J Woolf
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Judy S Liu
- Center for Neuroscience Research, Children's National Medical Center, Washington, DC 20010, USA
| | - Christopher V Gabel
- Departments of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118, USA
| | - Judith A Steen
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
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Li C, Hisamoto N, Matsumoto K. Axon Regeneration Is Regulated by Ets-C/EBP Transcription Complexes Generated by Activation of the cAMP/Ca2+ Signaling Pathways. PLoS Genet 2015; 11:e1005603. [PMID: 26484536 PMCID: PMC4618690 DOI: 10.1371/journal.pgen.1005603] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 09/23/2015] [Indexed: 11/19/2022] Open
Abstract
The ability of specific neurons to regenerate their axons after injury is governed by cell-intrinsic regeneration pathways. In Caenorhabditis elegans, the JNK and p38 MAPK pathways are important for axon regeneration. Axonal injury induces expression of the svh-2 gene encoding a receptor tyrosine kinase, stimulation of which by the SVH-1 growth factor leads to activation of the JNK pathway. Here, we identify ETS-4 and CEBP-1, related to mammalian Ets and C/EBP, respectively, as transcriptional activators of svh-2 expression following axon injury. ETS-4 and CEBP-1 function downstream of the cAMP and Ca2+-p38 MAPK pathways, respectively. We show that PKA-dependent phosphorylation of ETS-4 promotes its complex formation with CEBP-1. Furthermore, activation of both cAMP and Ca2+ signaling is required for activation of svh-2 expression. Thus, the cAMP/Ca2+ signaling pathways cooperatively activate the JNK pathway, which then promotes axon regeneration.
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Affiliation(s)
- Chun Li
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
| | - Naoki Hisamoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
- * E-mail: (NH); (KM)
| | - Kunihiro Matsumoto
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya, Japan
- * E-mail: (NH); (KM)
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246
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Abstract
UNLABELLED Chronic spinal cord injury (SCI) is a formidable hurdle that prevents a large number of injured axons from crossing the lesion, particularly the corticospinal tract (CST). This study shows that Pten deletion in the adult mouse cortex enhances compensatory sprouting of uninjured CST axons. Furthermore, forced upregulation of mammalian target of rapamycin (mTOR) initiated either 1 month or 1 year after injury promoted regeneration of CST axons. Our results indicate that both developmental and injury-induced mTOR downregulation in corticospinal motor neurons can be reversed in adults. Modulating neuronal mTOR activity is a potential strategy for axon regeneration after chronic SCI. SIGNIFICANCE STATEMENT As one of the long descending tracts controlling voluntary movement, the corticospinal tract (CST) plays an important role for functional recovery after spinal cord injury. The regeneration of CST has been a major challenge in the field, especially after chronic injuries. Here we developed a strategy to modulate Pten/mammalian target of rapamycin signaling in adult corticospinal motor neurons in the postinjury paradigm. It not only promoted the sprouting of uninjured CST axons, but also enabled the regeneration of injured axons past the lesion in a mouse model of spinal cord injury, even when treatment was delayed up to 1 year after the original injury. The results considerably extend the window of opportunity for regenerating CST axons severed in spinal cord injuries.
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247
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Chen L, Chuang M, Koorman T, Boxem M, Jin Y, Chisholm AD. Axon injury triggers EFA-6 mediated destabilization of axonal microtubules via TACC and doublecortin like kinase. eLife 2015; 4. [PMID: 26339988 PMCID: PMC4596636 DOI: 10.7554/elife.08695] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 09/03/2015] [Indexed: 01/09/2023] Open
Abstract
Axon injury triggers a series of changes in the axonal cytoskeleton that are prerequisites for effective axon regeneration. In Caenorhabditis elegans the signaling protein Exchange Factor for ARF-6 (EFA-6) is a potent intrinsic inhibitor of axon regrowth. Here we show that axon injury triggers rapid EFA-6-dependent inhibition of axonal microtubule (MT) dynamics, concomitant with relocalization of EFA-6. EFA-6 relocalization and axon regrowth inhibition require a conserved 18-aa motif in its otherwise intrinsically disordered N-terminal domain. The EFA-6 N-terminus binds the MT-associated proteins TAC-1/Transforming-Acidic-Coiled-Coil, and ZYG-8/Doublecortin-Like-Kinase, both of which are required for regenerative growth cone formation, and which act downstream of EFA-6. After injury TAC-1 and EFA-6 transiently relocalize to sites marked by the MT minus end binding protein PTRN-1/Patronin. We propose that EFA-6 acts as a bifunctional injury-responsive regulator of axonal MT dynamics, acting at the cell cortex in the steady state and at MT minus ends after injury. DOI:http://dx.doi.org/10.7554/eLife.08695.001 In the nervous system, cells called neurons carry information around the body. These cells have long thin projections called axons that allow the information to pass very quickly along the cell to junctions with other neurons. Neurons in adult mammals are limited in their ability to regenerate, so any damage to axons, for example, due to a stroke or a brain injury, tends to be permanent. Therefore, an important goal in neuroscience research is to discover the genes and proteins that are involved in regenerating axons as this may make it possible to develop new therapies. An internal scaffold called the cytoskeleton supports the three-dimensional shape of the axons. Changes in the cytoskeleton are required to allow neurons to regenerate axons after injury, and drugs that stabilize filaments called microtubules in the cytoskeleton can promote these changes. Chen et al. used a technique called laser microsurgery to sever individual axons in a roundworm known as C. elegans and then observed whether these axons could regenerate. The experiments reveal that a protein called EFA-6 blocks the regeneration of neurons by preventing rearrangements in the cytoskeleton. EFA-6 is normally found at the membrane that surrounds the neuron. However, Chen et al. show that when the axon is damaged, this protein rapidly moves to areas near the ends of microtubule filaments. EFA-6 interacts with two other proteins that are associated with microtubules and are required for axons to be able to regenerate. Chen et al.'s findings demonstrate that several proteins that regulate microtubule filaments play a key role in regenerating axons. All three of these proteins are found in humans and other animals so they have the potential to be targeted by drug therapies in future. The next challenge is to understand the details of how EFA-6 activity is affected by axon injury, and how this alters the cytoskeleton. DOI:http://dx.doi.org/10.7554/eLife.08695.002
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Affiliation(s)
- Lizhen Chen
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States.,University of California, San Diego, La Jolla, United States
| | - Marian Chuang
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Thijs Koorman
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Mike Boxem
- Department of Biology, Utrecht University, Utrecht, Netherlands
| | - Yishi Jin
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States.,University of California, San Diego, La Jolla, United States.,Department of Cellular and Molecular Medicine, University of California, San Diego School of Medicine, La Jolla, United States
| | - Andrew D Chisholm
- Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
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248
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Pinkernelle J, Raffa V, Calatayud MP, Goya GF, Riggio C, Keilhoff G. Growth factor choice is critical for successful functionalization of nanoparticles. Front Neurosci 2015; 9:305. [PMID: 26388717 PMCID: PMC4557102 DOI: 10.3389/fnins.2015.00305] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 08/12/2015] [Indexed: 12/16/2022] Open
Abstract
Nanoparticles (NPs) show new characteristics compared to the corresponding bulk material. These nanoscale properties make them interesting for various applications in biomedicine and life sciences. One field of application is the use of magnetic NPs to support regeneration in the nervous system. Drug delivery requires a functionalization of NPs with bio-functional molecules. In our study, we functionalized self-made PEI-coated iron oxide NPs with nerve growth factor (NGF) and glial cell-line derived neurotrophic factor (GDNF). Next, we tested the bio-functionality of NGF in a rat pheochromocytoma cell line (PC12) and the bio-functionality of GDNF in an organotypic spinal cord culture. Covalent binding of NGF to PEI-NPs impaired bio-functionality of NGF, but non-covalent approach differentiated PC12 cells reliably. Non-covalent binding of GDNF showed a satisfying bio-functionality of GDNF:PEI-NPs, but turned out to be unstable in conjugation to the PEI-NPs. Taken together, our study showed the importance of assessing bio-functionality and binding stability of functionalized growth factors using proper biological models. It also shows that successful functionalization of magnetic NPs with growth factors is dependent on the used binding chemistry and that it is hardly predictable. For use as therapeutics, functionalization strategies have to be reproducible and future studies are needed.
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Affiliation(s)
- Josephine Pinkernelle
- Department of Nephrology and Hypertension, Diabetes and Endocrinology, Otto-von-Guericke University of MagdeburgMagdeburg, Germany
- Institute for Biochemistry and Cell Biology, Otto-von-Guericke University of MagdeburgMagdeburg, Germany
| | - Vittoria Raffa
- Department of Biology, University of PisaPisa, Italy
- Institute of Life Science, Scuola Superiore Sant' AnnaPisa, Italy
| | | | - Gerado F. Goya
- Aragon Institute of Nanosciences, University of ZaragozaZaragoza, Spain
- Department of Condensed Matter Physics, University of ZaragozaSpain
| | - Cristina Riggio
- Institute of Life Science, Scuola Superiore Sant' AnnaPisa, Italy
| | - Gerburg Keilhoff
- Department of Nephrology and Hypertension, Diabetes and Endocrinology, Otto-von-Guericke University of MagdeburgMagdeburg, Germany
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249
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DeFrancesco-Lisowitz A, Lindborg JA, Niemi JP, Zigmond RE. The neuroimmunology of degeneration and regeneration in the peripheral nervous system. Neuroscience 2015; 302:174-203. [PMID: 25242643 PMCID: PMC4366367 DOI: 10.1016/j.neuroscience.2014.09.027] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 09/08/2014] [Accepted: 09/10/2014] [Indexed: 12/25/2022]
Abstract
Peripheral nerves regenerate following injury due to the effective activation of the intrinsic growth capacity of the neurons and the formation of a permissive pathway for outgrowth due to Wallerian degeneration (WD). WD and subsequent regeneration are significantly influenced by various immune cells and the cytokines they secrete. Although macrophages have long been known to play a vital role in the degenerative process, recent work has pointed to their importance in influencing the regenerative capacity of peripheral neurons. In this review, we focus on the various immune cells, cytokines, and chemokines that make regeneration possible in the peripheral nervous system, with specific attention placed on the role macrophages play in this process.
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Affiliation(s)
| | - J A Lindborg
- Department of Neurosciences, Case Western Reserve University, Cleveland OH 44106-4975
| | - J P Niemi
- Department of Neurosciences, Case Western Reserve University, Cleveland OH 44106-4975
| | - R E Zigmond
- Department of Neurosciences, Case Western Reserve University, Cleveland OH 44106-4975
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250
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Abstract
Neurons are extremely polarized cells. Axon lengths often exceed the dimension of the neuronal cell body by several orders of magnitude. These extreme axonal lengths imply that neurons have mastered efficient mechanisms for long distance signaling between soma and synaptic terminal. These elaborate mechanisms are required for neuronal development and maintenance of the nervous system. Neurons can fine-tune long distance signaling through calcium wave propagation and bidirectional transport of proteins, vesicles, and mRNAs along microtubules. The signal transmission over extreme lengths also ensures that information about axon injury is communicated to the soma and allows for repair mechanisms to be engaged. This review focuses on the different mechanisms employed by neurons to signal over long axonal distances and how signals are interpreted in the soma, with an emphasis on proteomic studies. We also discuss how proteomic approaches could help further deciphering the signaling mechanisms operating over long distance in axons.
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Affiliation(s)
- Atsushi Saito
- From the ‡Department of Anatomy and Neurobiology, Washington University in St Louis, School of Medicine, St Louis, 63110, Missouri
| | - Valeria Cavalli
- From the ‡Department of Anatomy and Neurobiology, Washington University in St Louis, School of Medicine, St Louis, 63110, Missouri.
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