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Cao X, Zhang Y, Shi Y, Li Y, Gao L, Wang X, Sun L. Identification of critical mitochondrial hub gene for facial nerve regeneration. Biochem Cell Biol 2024; 102:179-193. [PMID: 38086039 DOI: 10.1139/bcb-2023-0224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024] Open
Abstract
Mitochondria play a critical role in nerve regeneration, yet the impact of gene expression changes related to mitochondria in facial nerve regeneration remains unknown. To address this knowledge gap, we analyzed the expression profile of the facial motor nucleus (FMN) using data obtained from the Gene Expression Omnibus (GEO) database (GSE162977). By comparing different time points in the data, we identified differentially expressed genes (DEGs). Additionally, we collected mitochondria-related genes from the Gene Ontology (GO) database and intersected them with the DEGs, resulting in the identification of mitochondria-related DEGs (MIT-DEGs). To gain further insights, we performed functional enrichment and pathway analysis of the MIT-DEGs. To explore the interactions among these MIT-DEGs, we constructed a protein-protein interaction (PPI) network using the STRING database and identified hub genes using the Degree algorithm of Cytoscape software. To validate the relevance of these genes to nerve regeneration, we established a rat facial nerve injury (FNI) model and conducted a series of experiments. Through these experiments, we confirmed three MIT-DEGs (Myc, Lyn, and Cdk1) associated with facial nerve regeneration. Our findings provide valuable insights into the transcriptional changes of mitochondria-related genes in the FMN following FNI, which can contribute to the development of new treatment strategies for FNI.
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Affiliation(s)
- Xiaofang Cao
- Department of Dentistry, The Second Affiliated Hospital, Harbin Medical University, Harbin, China
- Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin Medical University, Harbin, China
| | - Yan Zhang
- Department of Dentistry, The Second Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Yu Shi
- Department of Dentistry, The Second Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Ying Li
- Heilongjiang Provincial Key Laboratory of Hard Tissue Development and Regeneration, Harbin Medical University, Harbin, China
- Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Li Gao
- Department of Dentistry, The Second Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Xiumei Wang
- Department of Dentistry, The Second Affiliated Hospital, Harbin Medical University, Harbin, China
| | - Liang Sun
- Department of Human Anatomy, School of Basic Medicine, Harbin Medical University, Harbin, China
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2
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De Virgiliis F, Mueller F, Palmisano I, Chadwick JS, Luengo-Gutierrez L, Giarrizzo A, Yan Y, Danzi MC, Picon-Muñoz C, Zhou L, Kong G, Serger E, Hutson TH, Maldonado-Lasuncion I, Song Y, Scheiermann C, Brancaccio M, Di Giovanni S. The circadian clock time tunes axonal regeneration. Cell Metab 2023; 35:2153-2164.e4. [PMID: 37951214 DOI: 10.1016/j.cmet.2023.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 08/18/2023] [Accepted: 10/16/2023] [Indexed: 11/13/2023]
Abstract
Nerve injuries cause permanent neurological disability due to limited axonal regeneration. Injury-dependent and -independent mechanisms have provided important insight into neuronal regeneration, however, common denominators underpinning regeneration remain elusive. A comparative analysis of transcriptomic datasets associated with neuronal regenerative ability revealed circadian rhythms as the most significantly enriched pathway. Subsequently, we demonstrated that sensory neurons possess an endogenous clock and that their regenerative ability displays diurnal oscillations in a murine model of sciatic nerve injury. Consistently, transcriptomic analysis showed a time-of-day-dependent enrichment for processes associated with axonal regeneration and the circadian clock. Conditional deletion experiments demonstrated that Bmal1 is required for neuronal intrinsic circadian regeneration and target re-innervation. Lastly, lithium enhanced nerve regeneration in wild-type but not in clock-deficient mice. Together, these findings demonstrate that the molecular clock fine-tunes the regenerative ability of sensory neurons and propose compounds affecting clock pathways as a novel approach to nerve repair.
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Affiliation(s)
- Francesco De Virgiliis
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK; Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland.
| | - Franziska Mueller
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Ilaria Palmisano
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK; Department of Neuroscience, Ohio State College of Medicine, Columbus, OH 43210, USA
| | - Jessica Sarah Chadwick
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Lucia Luengo-Gutierrez
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Angela Giarrizzo
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Yuyang Yan
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Matt Christopher Danzi
- Department of Human Genetics and Hussman Institute for Human Genomics, University of Miami, Miami, FL 33136, USA
| | - Carmen Picon-Muñoz
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland
| | - Luming Zhou
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Guiping Kong
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Elisabeth Serger
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Thomas Haynes Hutson
- Defitech Center for Interventional Neurotherapies (NeuroRestore), EPFL/CHUV/UNIL, Lausanne 1015, Switzerland
| | - Ines Maldonado-Lasuncion
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Yayue Song
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK
| | - Christoph Scheiermann
- Department of Pathology and Immunology, University of Geneva, Geneva 1211, Switzerland
| | - Marco Brancaccio
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK; UK Dementia Research Institute at Imperial College London, London W120NN, UK.
| | - Simone Di Giovanni
- Division of Neuroscience, Department of Brain Sciences, Imperial College London, London W120NN, UK.
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3
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Stewart AN, Gensel JC, Jones L, Fouad K. Challenges in Translating Regenerative Therapies for Spinal Cord Injury. Top Spinal Cord Inj Rehabil 2023; 29:23-43. [PMID: 38174141 PMCID: PMC10759906 DOI: 10.46292/sci23-00044s] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Regenerating the injured spinal cord is a substantial challenge with many obstacles that need to be overcome to achieve robust functional benefits. This abundance of hurdles can partly explain the limited success when applying regenerative intervention treatments in animal models and/or people. In this article, we elaborate on a few of these obstacles, starting with the applicability of animal models and how they compare to the clinical setting. We then discuss the requirement for combinatorial interventions and the associated problems in experimental design, including the addition of rehabilitative training. The article expands on differences in lesion sizes and locations between humans and common animal models, and how this difference can determine the success or failure of an intervention. An additional and frequently overlooked problem in the translation of interventions that applies beyond the field of neuroregeneration is the reporting bias and the lack of transparency in reporting findings. New data mandates are tackling this problem and will eventually result in a more balanced view of the field. Finally, we will discuss strategies to negotiate the challenging course of successful translation to facilitate successful translation of regeneration promoting interventions.
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Affiliation(s)
- Andrew N. Stewart
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky, USA
| | - John C. Gensel
- Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky, USA
| | - Linda Jones
- Department of Occupational Therapy, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Karim Fouad
- Department of Physical Therapy, University of Alberta, Edmonton, Canada
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4
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Bandla AC, Sheth AS, Zarate SM, Uskamalla S, Hager EC, Villarreal VA, González-García M, Ballestero RP. Enhancing structural plasticity of PC12 neurons during differentiation and neurite regeneration with a catalytically inactive mutant version of the zRICH protein. BMC Neurosci 2023; 24:43. [PMID: 37612637 PMCID: PMC10463786 DOI: 10.1186/s12868-023-00808-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 06/23/2023] [Indexed: 08/25/2023] Open
Abstract
BACKGROUND Studies of the molecular mechanisms of nerve regeneration have led to the discovery of several proteins that are induced during successful nerve regeneration. RICH proteins were identified as proteins induced during the regeneration of the optic nerve of teleost fish. These proteins are 2',3'-cyclic nucleotide, 3'-phosphodiesterases that can bind to cellular membranes through a carboxy-terminal membrane localization domain. They interact with the tubulin cytoskeleton and are able to enhance neuronal structural plasticity by promoting the formation of neurite branches. RESULTS PC12 stable transfectant cells expressing a fusion protein combining a red fluorescent protein with a catalytically inactive mutant version of zebrafish RICH protein were generated. These cells were used as a model to analyze effects of the protein on neuritogenesis. Differentiation experiments showed a 2.9 fold increase in formation of secondary neurites and a 2.4 fold increase in branching points. A 2.2 fold increase in formation of secondary neurites was observed in neurite regeneration assays. CONCLUSIONS The use of a fluorescent fusion protein facilitated detection of expression levels. Two computer-assisted morphometric analysis methods indicated that the catalytically inactive RICH protein induced the formation of branching points and secondary neurites both during differentiation and neurite regeneration. A procedure based on analysis of random field images provided comparable results to classic neurite tracing methods.
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Affiliation(s)
- Ashoka C Bandla
- Department of Biological and Health Sciences, Texas A&M University-Kingsville, 700 University Blvd, Kingsville, TX, 78363, USA
| | - Aditya S Sheth
- Department of Biological and Health Sciences, Texas A&M University-Kingsville, 700 University Blvd, Kingsville, TX, 78363, USA
| | - Sara M Zarate
- Department of Biological and Health Sciences, Texas A&M University-Kingsville, 700 University Blvd, Kingsville, TX, 78363, USA
| | - Suraj Uskamalla
- Department of Biological and Health Sciences, Texas A&M University-Kingsville, 700 University Blvd, Kingsville, TX, 78363, USA
| | - Elizabeth C Hager
- Department of Biological and Health Sciences, Texas A&M University-Kingsville, 700 University Blvd, Kingsville, TX, 78363, USA
| | - Victor A Villarreal
- Department of Chemistry, Texas A&M University-Kingsville, Kingsville, TX, 78363, USA
| | | | - Rafael P Ballestero
- Department of Biological and Health Sciences, Texas A&M University-Kingsville, 700 University Blvd, Kingsville, TX, 78363, USA.
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5
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Cheah M, Cheng Y, Petrova V, Cimpean A, Jendelova P, Swarup V, Woolf CJ, Geschwind DH, Fawcett JW. Integrin-Driven Axon Regeneration in the Spinal Cord Activates a Distinctive CNS Regeneration Program. J Neurosci 2023; 43:4775-4794. [PMID: 37277179 PMCID: PMC10312060 DOI: 10.1523/jneurosci.2076-22.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 04/19/2023] [Accepted: 04/21/2023] [Indexed: 06/07/2023] Open
Abstract
The peripheral branch of sensory dorsal root ganglion (DRG) neurons regenerates readily after injury unlike their central branch in the spinal cord. However, extensive regeneration and reconnection of sensory axons in the spinal cord can be driven by the expression of α9 integrin and its activator kindlin-1 (α9k1), which enable axons to interact with tenascin-C. To elucidate the mechanisms and downstream pathways affected by activated integrin expression and central regeneration, we conducted transcriptomic analyses of adult male rat DRG sensory neurons transduced with α9k1, and controls, with and without axotomy of the central branch. Expression of α9k1 without the central axotomy led to upregulation of a known PNS regeneration program, including many genes associated with peripheral nerve regeneration. Coupling α9k1 treatment with dorsal root axotomy led to extensive central axonal regeneration. In addition to the program upregulated by α9k1 expression, regeneration in the spinal cord led to expression of a distinctive CNS regeneration program, including genes associated with ubiquitination, autophagy, endoplasmic reticulum (ER), trafficking, and signaling. Pharmacological inhibition of these processes blocked the regeneration of axons from DRGs and human iPSC-derived sensory neurons, validating their causal contributions to sensory regeneration. This CNS regeneration-associated program showed little correlation with either embryonic development or PNS regeneration programs. Potential transcriptional drivers of this CNS program coupled to regeneration include Mef2a, Runx3, E2f4, and Yy1. Signaling from integrins primes sensory neurons for regeneration, but their axon growth in the CNS is associated with an additional distinctive program that differs from that involved in PNS regeneration.SIGNIFICANCE STATEMENT Restoration of neurologic function after spinal cord injury has yet to be achieved in human patients. To accomplish this, severed nerve fibers must be made to regenerate. Reconstruction of nerve pathways has not been possible, but recently, a method for stimulating long-distance axon regeneration of sensory fibers in rodents has been developed. This research uses profiling of messenger RNAs in the regenerating sensory neurons to discover which mechanisms are activated. This study shows that the regenerating neurons initiate a novel CNS regeneration program which includes molecular transport, autophagy, ubiquitination, and modulation of the endoplasmic reticulum (ER). The study identifies mechanisms that neurons need to activate to regenerate their nerve fibers.
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Affiliation(s)
- Menghon Cheah
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, United Kingdom
| | - Yuyan Cheng
- Program in Neurogenetics, Department of Neurology, and Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - Veselina Petrova
- Department of Neurobiology, Harvard Medical School; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Anda Cimpean
- Centre for Reconstructive Neuroscience, Institute of Experimental Medicine Czech Academy of Science, Prague, Czech Republic
| | - Pavla Jendelova
- Centre for Reconstructive Neuroscience, Institute of Experimental Medicine Czech Academy of Science, Prague, Czech Republic
| | - Vivek Swarup
- Program in Neurogenetics, Department of Neurology, and Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California 90095
- Department of Neurobiology and Behavior, University of California, Irvine, California 92697
| | - Clifford J Woolf
- Department of Neurobiology, Harvard Medical School; F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts 02115
| | - Daniel H Geschwind
- Program in Neurogenetics, Department of Neurology, and Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, California 90095
| | - James W Fawcett
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge CB2 0PY, United Kingdom
- Centre for Reconstructive Neuroscience, Institute of Experimental Medicine Czech Academy of Science, Prague, Czech Republic
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6
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Rizk E, Madrid A, Koueik J, Sun D, Stewart K, Chen D, Luo S, Hong F, Papale LA, Hariharan N, Alisch RS, Iskandar BJ. Purified regenerating retinal neurons reveal regulatory role of DNA methylation-mediated Na+/K+-ATPase in murine axon regeneration. Commun Biol 2023; 6:120. [PMID: 36717618 PMCID: PMC9886953 DOI: 10.1038/s42003-023-04463-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
While embryonic mammalian central nervous system (CNS) axons readily grow and differentiate, only a minority of fully differentiated mature CNS neurons are able to regenerate injured axons, leading to stunted functional recovery after injury and disease. To delineate DNA methylation changes specifically associated with axon regeneration, we used a Fluorescent-Activated Cell Sorting (FACS)-based methodology in a rat optic nerve transection model to segregate the injured retinal ganglion cells (RGCs) into regenerating and non-regenerating cell populations. Whole-genome DNA methylation profiling of these purified neurons revealed genes and pathways linked to mammalian RGC regeneration. Moreover, whole-methylome sequencing of purified uninjured adult and embryonic RGCs identified embryonic molecular profiles reactivated after injury in mature neurons, and others that correlate specifically with embryonic or adult axon growth, but not both. The results highlight the contribution to both embryonic growth and adult axon regeneration of subunits encoding the Na+/K+-ATPase. In turn, both biochemical and genetic inhibition of the Na+/K+-ATPase pump significantly reduced RGC axon regeneration. These data provide critical molecular insights into mammalian CNS axon regeneration, pinpoint the Na+/K+-ATPase as a key regulator of regeneration of injured mature CNS axons, and suggest that successful regeneration requires, in part, reactivation of embryonic signals.
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Affiliation(s)
- Elias Rizk
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA ,grid.240473.60000 0004 0543 9901Department of Neurological Surgery, Penn State Milton S. Hershey Medical Center, Hershey, PA 17033 USA
| | - Andy Madrid
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Joyce Koueik
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Dandan Sun
- grid.21925.3d0000 0004 1936 9000Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213 USA
| | - Krista Stewart
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - David Chen
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Susan Luo
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Felissa Hong
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Ligia A. Papale
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Nithya Hariharan
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Reid S. Alisch
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
| | - Bermans J. Iskandar
- grid.14003.360000 0001 2167 3675Department of Neurological Surgery, University of Wisconsin-Madison School of Medicine and Public Health, Madison, WI 53792 USA
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7
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Intrinsic heterogeneity in axon regeneration. Biochem Soc Trans 2022; 50:1753-1762. [DOI: 10.1042/bst20220624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/01/2022] [Accepted: 11/07/2022] [Indexed: 11/18/2022]
Abstract
The nervous system is composed of a variety of neurons and glial cells with different morphology and functions. In the mammalian peripheral nervous system (PNS) or the lower vertebrate central nervous system (CNS), most neurons can regenerate extensively after axotomy, while the neurons in the mammalian CNS possess only limited regenerative ability. This heterogeneity is common within and across species. The studies about the transcriptomes after nerve injury in different animal models have revealed a series of molecular and cellular events that occurred in neurons after axotomy. However, responses of various types of neurons located in different positions of individuals were different remarkably. Thus, researchers aim to find the key factors that are conducive to regeneration, so as to provide the molecular basis for solving the regeneration difficulties after CNS injury. Here we review the heterogeneity of axonal regeneration among different cell subtypes in different animal models or the same organ, emphasizing the importance of comparative studies within and across species.
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8
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O'Brien AL, West JM, Saffari TM, Nguyen M, Moore AM. Promoting Nerve Regeneration: Electrical Stimulation, Gene Therapy, and Beyond. Physiology (Bethesda) 2022; 37:0. [PMID: 35820181 DOI: 10.1152/physiol.00008.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Peripheral nerve injuries often result in life-altering functional deficits even with optimal management. Unlike the central nervous system, peripheral nerves have the ability to regenerate lost axons after injury; however, axonal regeneration does not equate to full restoration of function. To overcome this physiological shortcoming, advances in nerve regeneration and repair are paramount, including electrical stimulation, gene therapy, and surgical technique advancements.
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Affiliation(s)
- Andrew L O'Brien
- Department of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Julie M West
- Department of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Tiam M Saffari
- Department of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Minh Nguyen
- Department of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
| | - Amy M Moore
- Department of Plastic and Reconstructive Surgery, The Ohio State University Wexner Medical Center, Columbus, Ohio
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9
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Chernov AV, Shubayev VI. Sexually dimorphic transcriptional programs of early-phase response in regenerating peripheral nerves. Front Mol Neurosci 2022; 15:958568. [PMID: 35983069 PMCID: PMC9378824 DOI: 10.3389/fnmol.2022.958568] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/04/2022] [Indexed: 11/13/2022] Open
Abstract
The convergence of transcriptional and epigenetic changes in the peripheral nervous system (PNS) reshapes the spatiotemporal gene expression landscape in response to nerve transection. The control of these molecular programs exhibits sexually dimorphic characteristics that remain not sufficiently characterized. In the present study, we recorded genome-wide and sex-dependent early-phase transcriptional changes in regenerating (proximal) sciatic nerve 24 h after axotomy. Male nerves exhibited more extensive transcriptional changes with male-dominant upregulation of cytoskeletal binding and structural protein genes. Regulation of mRNAs encoding ion and ionotropic neurotransmitter channels displayed prominent sexual dimorphism consistent with sex-specific mRNA axonal transport in an early-phase regenerative response. Protein kinases and axonal transport genes showed sexually dimorphic regulation. Genes encoding components of synaptic vesicles were at high baseline expression in females and showed post-injury induction selectively in males. Predictive bioinformatic analyses established patterns of sexually dimorphic regulation of neurotrophic and immune genes, including activation of glial cell line-derived neurotrophic factor Gfra1 receptor and immune checkpoint cyclin D1 (Ccnd1) potentially linked to X-chromosome encoded tissue inhibitor of matrix metallo proteinases 1 (Timp1). Regulatory networks involving Olig1, Pou3f3/Oct6, Myrf, and Myt1l transcription factors were linked to sex-dependent reprogramming in regenerating nerves. Differential expression patterns of non-coding RNAs motivate a model of sexually dimorphic nerve regenerative responses to injury determined by epigenetic factors. Combined with our findings in the corresponding dorsal root ganglia (DRG), unique early-phase sex-specific molecular triggers could enrich the mechanistic understanding of peripheral neuropathies.
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Affiliation(s)
- Andrei V. Chernov
- Department of Anesthesiology, University of California, San Diego, San Diego, CA, United States
- VA San Diego Healthcare System, San Diego, CA, United States
- *Correspondence: Andrei V. Chernov,
| | - Veronica I. Shubayev
- Department of Anesthesiology, University of California, San Diego, San Diego, CA, United States
- VA San Diego Healthcare System, San Diego, CA, United States
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10
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Chernov AV, Shubayev VI. Sexual Dimorphism of Early Transcriptional Reprogramming in Dorsal Root Ganglia After Peripheral Nerve Injury. Front Mol Neurosci 2021; 14:779024. [PMID: 34966260 PMCID: PMC8710713 DOI: 10.3389/fnmol.2021.779024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/19/2021] [Indexed: 01/18/2023] Open
Abstract
Peripheral nerve injury induces genome-wide transcriptional reprogramming of first-order neurons and auxiliary cells of dorsal root ganglia (DRG). Accumulating experimental evidence suggests that onset and mechanistic principles of post-nerve injury processes are sexually dimorphic. We examined largely understudied aspects of early transcriptional events in DRG within 24 h after sciatic nerve axotomy in mice of both sexes. Using high-depth RNA sequencing (>50 million reads/sample) to pinpoint sexually dimorphic changes related to regeneration, immune response, bioenergy, and sensory functions, we identified a higher number of transcriptional changes in male relative to female DRG. In males, the decline in ion channel transcripts was accompanied by the induction of innate immune cascades via TLR, chemokine, and Csf1-receptor axis and robust regenerative programs driven by Sox, Twist1/2, and Pax5/9 transcription factors. Females demonstrated nerve injury-specific transcriptional co-activation of the actinin 2 network. The predicted upstream regulators and interactive networks highlighted the role of novel epigenetic factors and genetic linkage to sex chromosomes as hallmarks of gene regulation post-axotomy. We implicated epigenetic X chromosome inactivation in the regulation of immune response activity uniquely in females. Sexually dimorphic regulation of MMP/ADAMTS metalloproteinases and their intrinsic X-linked regulator Timp1 contributes to extracellular matrix remodeling integrated with pro-regenerative and immune functions. Lexis1 non-coding RNA involved in LXR-mediated lipid metabolism was identified as a novel nerve injury marker. Together, our data identified unique early response triggers of sex-specific peripheral nerve injury regulation to gain mechanistic insights into the origin of female- and male-prevalent sensory neuropathies.
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Affiliation(s)
- Andrei V Chernov
- Department of Anesthesiology, University of California, San Diego, San Diego, CA, United States.,VA San Diego Healthcare System, San Diego, CA, United States
| | - Veronica I Shubayev
- Department of Anesthesiology, University of California, San Diego, San Diego, CA, United States.,VA San Diego Healthcare System, San Diego, CA, United States
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11
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Boido M, Vercelli A. Genes and miRNAs as Hurdles and Promoters of Corticospinal Tract Regeneration in Spinal Cord Injury. Front Cell Dev Biol 2021; 9:748911. [PMID: 34722529 PMCID: PMC8554128 DOI: 10.3389/fcell.2021.748911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 09/27/2021] [Indexed: 11/24/2022] Open
Abstract
Spinal cord injury (SCI) is a devastating lesion to the spinal cord, which determines the interruption of ascending/descending axonal tracts, the loss of supraspinal control of sensory-motor functions below the injured site, and severe autonomic dysfunctions, dramatically impacting the quality of life of the patients. After the acute inflammatory phase, the progressive formation of the astrocytic glial scar characterizes the acute-chronic phase: such scar represents one of the main obstacles to the axonal regeneration that, as known, is very limited in the central nervous system (CNS). Unfortunately, a cure for SCI is still lacking: the current clinical approaches are mainly based on early vertebral column stabilization, anti-inflammatory drug administration, and rehabilitation programs. However, new experimental therapeutic strategies are under investigation, one of which is to stimulate axonal regrowth and bypass the glial scar. One major issue in axonal regrowth consists of the different genetic programs, which characterize axonal development and maturation. Here, we will review the main hurdles that in adulthood limit axonal regeneration after SCI, describing the key genes, transcription factors, and miRNAs involved in these processes (seen their reciprocal influencing action), with particular attention to corticospinal motor neurons located in the sensory-motor cortex and subjected to axotomy in case of SCI. We will highlight the functional complexity of the neural regeneration programs. We will also discuss if specific axon growth programs, that undergo a physiological downregulation during CNS development, could be reactivated after a spinal cord trauma to sustain regrowth, representing a new potential therapeutic approach.
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Affiliation(s)
- Marina Boido
- Department of Neuroscience "Rita Levi Montalcini", Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
| | - Alessandro Vercelli
- Department of Neuroscience "Rita Levi Montalcini", Neuroscience Institute Cavalieri Ottolenghi, University of Turin, Turin, Italy
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12
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Cheng YC, Snavely A, Barrett LB, Zhang X, Herman C, Frost DJ, Riva P, Tochitsky I, Kawaguchi R, Singh B, Ivanis J, Huebner EA, Arvanites A, Oza V, Davidow L, Maeda R, Sakuma M, Grantham A, Wang Q, Chang AN, Pfaff K, Costigan M, Coppola G, Rubin LL, Schwer B, Alt FW, Woolf CJ. Topoisomerase I inhibition and peripheral nerve injury induce DNA breaks and ATF3-associated axon regeneration in sensory neurons. Cell Rep 2021; 36:109666. [PMID: 34496254 PMCID: PMC8462619 DOI: 10.1016/j.celrep.2021.109666] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/16/2021] [Accepted: 08/13/2021] [Indexed: 11/24/2022] Open
Abstract
Although axonal damage induces rapid changes in gene expression in primary sensory neurons, it remains unclear how this process is initiated. The transcription factor ATF3, one of the earliest genes responding to nerve injury, regulates expression of downstream genes that enable axon regeneration. By exploiting ATF3 reporter systems, we identify topoisomerase inhibitors as ATF3 inducers, including camptothecin. Camptothecin increases ATF3 expression and promotes neurite outgrowth in sensory neurons in vitro and enhances axonal regeneration after sciatic nerve crush in vivo. Given the action of topoisomerases in producing DNA breaks, we determine that they do occur immediately after nerve damage at the ATF3 gene locus in injured sensory neurons and are further increased after camptothecin exposure. Formation of DNA breaks in injured sensory neurons and enhancement of it pharmacologically may contribute to the initiation of those transcriptional changes required for peripheral nerve regeneration.
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Affiliation(s)
- Yung-Chih Cheng
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew Snavely
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Lee B Barrett
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Xuefei Zhang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Crystal Herman
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Devlin J Frost
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Priscilla Riva
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Ivan Tochitsky
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Riki Kawaguchi
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Bhagat Singh
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Jelena Ivanis
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Eric A Huebner
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Anthony Arvanites
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Vatsal Oza
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Lance Davidow
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Rie Maeda
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Miyuki Sakuma
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Alyssa Grantham
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Qing Wang
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Amelia N Chang
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Kathleen Pfaff
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Michael Costigan
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Anaesthesia Department, Boston Children's Hospital, Boston, MA 02115, USA
| | - Giovanni Coppola
- Departments of Psychiatry and Neurology, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Bjoern Schwer
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Frederick W Alt
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Howard Hughes Medical Institute, Boston, MA 02115, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA; Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
| | - Clifford J Woolf
- F.M. Kirby Neurobiology Center, Program in Neurobiology, Boston Children's Hospital, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA.
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13
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van Erp S, van Berkel AA, Feenstra EM, Sahoo PK, Wagstaff LJ, Twiss JL, Fawcett JW, Eva R, Ffrench-Constant C. Age-related loss of axonal regeneration is reflected by the level of local translation. Exp Neurol 2021; 339:113594. [PMID: 33450233 PMCID: PMC8024785 DOI: 10.1016/j.expneurol.2020.113594] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 12/07/2020] [Accepted: 12/17/2020] [Indexed: 01/08/2023]
Abstract
Regeneration capacity is reduced as CNS axons mature. Using laser-mediated axotomy, proteomics and puromycin-based tagging of newly-synthesized proteins in a human embryonic stem cell-derived neuron culture system that allows isolation of axons from cell bodies, we show here that efficient regeneration in younger axons (d45 in culture) is associated with local axonal protein synthesis (local translation). Enhanced regeneration, promoted by co-culture with human glial precursor cells, is associated with increased axonal synthesis of proteins, including those constituting the translation machinery itself. Reduced regeneration, as occurs with the maturation of these axons by d65 in culture, correlates with reduced levels of axonal proteins involved in translation and an inability to respond by increased translation of regeneration promoting axonal mRNAs released from stress granules. Together, our results provide evidence that, as in development and in the PNS, local translation contributes to CNS axon regeneration.
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Affiliation(s)
- Susan van Erp
- MRC Centre for Regenerative Medicine and MS Society Edinburgh Centre, Edinburgh bioQuarter, University of Edinburgh, Edinburgh, UK.
| | - Annemiek A van Berkel
- Department of Functional Genomics, Center for Neurogenomics and Cognitive Research (CNCR), VU University Amsterdam, De Boelelaan 1085, 1081, HV, Amsterdam, the Netherlands
| | - Eline M Feenstra
- MRC Centre for Regenerative Medicine and MS Society Edinburgh Centre, Edinburgh bioQuarter, University of Edinburgh, Edinburgh, UK
| | - Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia 29208, SC, USA
| | - Laura J Wagstaff
- MRC Centre for Regenerative Medicine and MS Society Edinburgh Centre, Edinburgh bioQuarter, University of Edinburgh, Edinburgh, UK
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia 29208, SC, USA
| | - James W Fawcett
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK; Centre for Reconstructive Neuroscience, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic
| | - Richard Eva
- John van Geest Centre for Brain Repair, Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Charles Ffrench-Constant
- MRC Centre for Regenerative Medicine and MS Society Edinburgh Centre, Edinburgh bioQuarter, University of Edinburgh, Edinburgh, UK
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Role of Myc Proto-Oncogene as a Transcriptional Hub to Regulate the Expression of Regeneration-Associated Genes following Preconditioning Peripheral Nerve Injury. J Neurosci 2021; 41:446-460. [PMID: 33262248 DOI: 10.1523/jneurosci.1745-20.2020] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 11/16/2020] [Accepted: 11/18/2020] [Indexed: 12/20/2022] Open
Abstract
Preconditioning peripheral nerve injury enhances the intrinsic growth capacity of DRGs sensory axons by inducing transcriptional upregulation of the regeneration-associated genes (RAGs). However, it is still unclear how preconditioning injury leads to the orchestrated induction of many RAGs. The present study identified Myc proto-oncogene as a transcriptional hub gene to regulate the expression of a distinct subset of RAGs in DRGs following the preconditioning injury. We demonstrated that c-MYC bound to the promoters of certain RAGs, such as Jun, Atf3, and Sprr1a, and that Myc upregulation following SNI preceded that of the RAGs bound by c-MYC. Marked DNA methylation of the Myc exon 3 sequences was implicated in the early transcriptional activation and accompanied by open histone marks. Myc deletion led to a decrease in the injury-induced expression of a distinct subset of RAGs, which were highly overlapped with the list of RAGs that were upregulated by Myc overexpression. Following dorsal hemisection spinal cord injury in female rats, Myc overexpression in DRGs significantly prevented the retraction of the sensory axons in a manner dependent on its downstream RAG, June Our results suggest that Myc plays a critical role in axon regeneration via its transcriptional activity to regulate the expression of a spectrum of downstream RAGs and subsequent effector molecules. Identification of more upstream hub transcription factors and the epigenetic mechanisms specific for individual hub transcription factors would advance our understanding of how the preconditioning injury induces orchestrated upregulation of RAGs.
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Kampanis V, Tolou-Dabbaghian B, Zhou L, Roth W, Puttagunta R. Cyclic Stretch of Either PNS or CNS Located Nerves Can Stimulate Neurite Outgrowth. Cells 2020; 10:cells10010032. [PMID: 33379276 PMCID: PMC7824691 DOI: 10.3390/cells10010032] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/21/2020] [Accepted: 12/22/2020] [Indexed: 12/15/2022] Open
Abstract
The central nervous system (CNS) does not recover from traumatic axonal injury, but the peripheral nervous system (PNS) does. We hypothesize that this fundamental difference in regenerative capacity may be based upon the absence of stimulatory mechanical forces in the CNS due to the protective rigidity of the vertebral column and skull. We developed a bioreactor to apply low-strain cyclic axonal stretch to adult rat dorsal root ganglia (DRG) connected to either the peripheral or central nerves in an explant model for inducing axonal growth. In response, larger diameter DRG neurons, mechanoreceptors and proprioceptors showed enhanced neurite outgrowth as well as increased Activating Transcription Factor 3 (ATF3).
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Affiliation(s)
- Vasileios Kampanis
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany; (V.K.); (B.T.-D.)
| | - Bahardokht Tolou-Dabbaghian
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany; (V.K.); (B.T.-D.)
| | - Luming Zhou
- Laboratory of NeuroRegeneration and Repair, Hertie Institute for Clinical Brain Research, University of Tübingen, 72076 Tübingen, Germany;
| | - Wolfgang Roth
- Laboratory for Experimental Neurorehabilitation, Heidelberg University Hospital, 69118 Heidelberg, Germany;
| | - Radhika Puttagunta
- Laboratory for Experimental Neuroregeneration, Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany; (V.K.); (B.T.-D.)
- Correspondence:
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Atrophy and Death of Nonpeptidergic and Peptidergic Nociceptive Neurons in SIV Infection. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1530-1544. [PMID: 32246920 DOI: 10.1016/j.ajpath.2020.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 03/06/2020] [Accepted: 03/20/2020] [Indexed: 11/21/2022]
Abstract
HIV-associated sensory neuropathy is a common neurologic comorbidity of HIV infection and prevails in the post-antiretroviral therapy (ART) era. HIV infection drives pathologic changes in the dorsal root ganglia (DRG) through inflammation, altered metabolism, and neuronal dysfunction. Herein, we characterized specific neuronal populations in an SIV-infected macaque model with or without ART. DRG neuronal populations were identified by neurofilament H-chain 200, I-B4 isolectin (IB4), or tropomyosin receptor kinase A expression and assessed for cell body diameter, population size, apoptotic markers, and regeneration signaling. IB4+ and tropomyosin receptor kinase A-positive neurons showed a reduced cell body size (atrophy) and decreased population size (cell death) in the DRG of SIV-infected animals compared with uninfected animals. IB4+ nonpeptidergic neurons were less affected in the presence of ART. DRG neurons showed accumulation of cleaved caspase 3 (apoptosis) and nuclear-localized activating transcription factor 3 (regeneration) in SIV infection, which was significantly lower in uninfected animals and SIV-infected animals receiving ART. Nonpeptidergic neurons predominantly colocalized with cleaved caspase 3 staining. Nonpeptidergic and peptidergic neurons colocalized with nuclear-accumulated activating transcription factor 3, showing active regeneration in sensory neurons. These data suggest that nonpeptidergic and peptidergic neurons are susceptible to pathologic changes from SIV infection, and intervention with ART did not fully ameliorate damage to the DRG, specifically to peptidergic neurons.
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Shin HY, Kim K, Kwon MJ, Oh YJ, Kim EH, Kim HS, Hong CP, Lee JH, Lee K, Kim BG. Alteration in global DNA methylation status following preconditioning injury influences axon growth competence of the sensory neurons. Exp Neurol 2020; 326:113177. [PMID: 31926166 DOI: 10.1016/j.expneurol.2020.113177] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Revised: 12/31/2019] [Accepted: 01/07/2020] [Indexed: 12/18/2022]
Abstract
Preconditioning peripheral nerve injury primes the sensory neurons in the dorsal root ganglia (DRGs) to acquire axon regeneration competence. Transcription of a large set of regeneration-associated-genes (RAGs) contributes to the enhanced intrinsic axonal regeneration capacity. However, the mechanism underlying the coordinated upregulation of RAGs orchestrated by preconditioning injury is unclear. We sought to determine potential influence of DNA methylation change on transcriptional activation of RAGs in the L4-L6 DRGs following sciatic nerve injury. Genome-wide sequencing revealed that about 20% of the methylated DNA fragments were differentially methylated, and >3000 genes contained differentially methylated regions. Not only demethylation but also increased methylation was observed to a similar extent. The change in the global DNA methylation did not correlate with the gene expression level of most genes, including the well-documented RAGs. However, pharmacological inhibition or activation of DNA methylation markedly attenuated the axon growth capacity of the preconditioned DRG neurons. Pharmacological perturbation of DNA methylation resulted in simultaneous downregulation of many highly overlapping non-transcription factor RAGs, which was accompanied by a concurrent, robust upregulation of SOCS3 and Serpine1. Overexpression of SOCS3 and Serpine1 in the DRG neurons overrode injury-induced axon growth competence, corroborating their roles as the negative regulators of axon regeneration. We conclude that the injury-induced global alteration of DNA methylome strongly influences the axon growth competence in preconditioned DRG neurons. Our results also suggest a possibility that perturbing DNA methylome changes might lead to the upregulation of negative regulator RAGs thereby attenuating axon growth capacity.
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Affiliation(s)
- Hae Young Shin
- Department of Brain Science, Ajou University Graduate School of Medicine, Suwon, Republic of Korea; Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Kyung Kim
- Department of Biomedical Informatics, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Min Jung Kwon
- Department of Brain Science, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Young Joo Oh
- Department of Brain Science, Ajou University Graduate School of Medicine, Suwon, Republic of Korea; Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Eun Hye Kim
- Department of Brain Science, Ajou University Graduate School of Medicine, Suwon, Republic of Korea; Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Hyung Soon Kim
- Department of Brain Science, Ajou University Graduate School of Medicine, Suwon, Republic of Korea; Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea
| | - Chang Pyo Hong
- Theragen Bio Institute, TheragenEtex, Suwon 16229, Republic of Korea
| | - Jae-Hyung Lee
- Department of Life and Nanopharmaceutical Sciences, Department of Maxillofacial Biomedical Engineering, School of Dentistry, Kyung Hee University, Republic of Korea
| | - KiYoung Lee
- Department of Biomedical Informatics, Ajou University School of Medicine, Suwon, Republic of Korea
| | - Byung Gon Kim
- Department of Brain Science, Ajou University Graduate School of Medicine, Suwon, Republic of Korea; Neuroscience Graduate Program, Department of Biomedical Sciences, Ajou University Graduate School of Medicine, Suwon, Republic of Korea; Department of Neurology, Ajou University School of Medicine, Suwon, Republic of Korea.
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18
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Rodemer W, Hu J, Selzer ME, Shifman MI. Heterogeneity in the regenerative abilities of central nervous system axons within species: why do some neurons regenerate better than others? Neural Regen Res 2020; 15:996-1005. [PMID: 31823869 PMCID: PMC7034288 DOI: 10.4103/1673-5374.270298] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Some neurons, especially in mammalian peripheral nervous system or in lower vertebrate or in vertebrate central nervous system (CNS) regenerate after axotomy, while most mammalian CNS neurons fail to regenerate. There is an emerging consensus that neurons have different intrinsic regenerative capabilities, which theoretically could be manipulated therapeutically to improve regeneration. Population-based comparisons between “good regenerating” and “bad regenerating” neurons in the CNS and peripheral nervous system of most vertebrates yield results that are inconclusive or difficult to interpret. At least in part, this reflects the great diversity of cells in the mammalian CNS. Using mammalian nervous system imposes several methodical limitations. First, the small sizes and large numbers of neurons in the CNS make it very difficult to distinguish regenerating neurons from non-regenerating ones. Second, the lack of identifiable neurons makes it impossible to correlate biochemical changes in a neuron with axonal damage of the same neuron, and therefore, to dissect the molecular mechanisms of regeneration on the level of single neurons. This review will survey the reported responses to axon injury and the determinants of axon regeneration, emphasizing non-mammalian model organisms, which are often under-utilized, but in which the data are especially easy to interpret.
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Affiliation(s)
- William Rodemer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Jianli Hu
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Michael E Selzer
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation); Department of Neurology, the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
| | - Michael I Shifman
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), the Lewis Katz School of Medicine at Temple University, Philadelphia, PA, USA
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PKCγ promotes axonal remodeling in the cortico-spinal tract via GSK3β/β-catenin signaling after traumatic brain injury. Sci Rep 2019; 9:17078. [PMID: 31745212 PMCID: PMC6863826 DOI: 10.1038/s41598-019-53225-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 07/22/2019] [Indexed: 12/27/2022] Open
Abstract
Traumatic brain injury (TBI) is a common cause of death and disability. Enhancing the midline-crossing of the contralateral corticospinal tract (CST) to the denervated side of spinal cord facilitates functional recovery after TBI. Activation of the gamma isoform of PKC (PKCγ) in contralateral CST implicates its roles in promoting CST remodeling after TBI. In this study, we deployed loss and gain of function strategies in N2a cells and primary cortical neurons in vitro, and demonstrated that PKCγ is not only important but necessary for neuronal differentiation, neurite outgrowth and axonal branching but not for axonal extension. Mechanically, through the phosphorylation of GSK3β, PKCγ stabilizes the expression of cytosolic β-catenin and increase GAP43 expression, thus promoting axonal outgrowth. Further, rAAV2/9-mediated delivery of constitutive PKCγ in the corticospinal tract after unilateral TBI in vivo additionally showed that specifically delivery of active PKCγ mutant to cortical neuron promotes midline crossing of corticospinal fibers from the uninjured side to the denervated cervical spinal cord. This PKCγ-mediated injury response promoted sensorimotor functional recovery. In conclusion, PKCγ mediates stability of β-catenin through the phosphorylation of GSK3β to facilitate neuronal differentiation, neurite outgrowth and axonal branching, and PKCγ maybe a novel therapeutic target for physiological and functional recovery after TBI.
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Expression and Manipulation of the APC-β-Catenin Pathway During Peripheral Neuron Regeneration. Sci Rep 2018; 8:13197. [PMID: 30181617 PMCID: PMC6123411 DOI: 10.1038/s41598-018-31167-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 08/03/2018] [Indexed: 02/07/2023] Open
Abstract
Molecules and pathways that suppress growth are expressed in postmitotic neurons, a potential advantage in mature neural networks, but a liability during regeneration. In this work, we probed the APC (adenomatous polyposis coli)-β-catenin partner pathway in adult peripheral sensory neurons during regeneration. APC had robust expression in the cytoplasm and perinuclear region of adult DRG sensory neurons both before and after axotomy injury. β-catenin was expressed in neuronal nuclei, neuronal cytoplasm and also in perineuronal satellite cells. In injured dorsal root ganglia (DRG) sensory neurons and their axons, we observed paradoxical APC upregulation, despite its role as an inhibitor of growth whereas β-catenin was downregulated. Inhibition of APC in adult sensory neurons and activation of β-catenin, LEF/TCF transcriptional factors were associated with increased neuronal plasticity in vitro. Local knockdown of APC, at the site of sciatic nerve crush injury enhanced evidence for electrophysiological, behavioural and structural regeneration in vivo. This was accompanied by upregulation of β-catenin. Collectively, the APC-β-catenin-LEF/TCF transcriptional pathway impacts intrinsic mechanisms of axonal regeneration and neuronal plasticity after injury, offering new options for addressing axon regeneration.
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21
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Palmisano I, Di Giovanni S. Advances and Limitations of Current Epigenetic Studies Investigating Mammalian Axonal Regeneration. Neurotherapeutics 2018; 15:529-540. [PMID: 29948919 PMCID: PMC6095777 DOI: 10.1007/s13311-018-0636-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Axonal regeneration relies on the expression of regenerative associated genes within a coordinated transcriptional programme, which is finely tuned as a result of the activation of several regenerative signalling pathways. In mammals, this chain of events occurs in neurons following peripheral axonal injury, however it fails upon axonal injury in the central nervous system, such as in the spinal cord and the brain. Accumulating evidence has been suggesting that epigenetic control is a key factor to initiate and sustain the regenerative transcriptional response and that it might contribute to regenerative success versus failure. This review will discuss experimental evidence so far showing a role for epigenetic regulation in models of peripheral and central nervous system axonal injury. It will also propose future directions to fill key knowledge gaps and to test whether epigenetic control might indeed discriminate between regenerative success and failure.
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Affiliation(s)
- Ilaria Palmisano
- Laboratory for Neuroregeneration, Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK.
| | - Simone Di Giovanni
- Laboratory for Neuroregeneration, Centre for Restorative Neuroscience, Division of Brain Sciences, Department of Medicine, Imperial College London, London, UK.
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22
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Förstner P, Rehman R, Anastasiadou S, Haffner-Luntzer M, Sinske D, Ignatius A, Roselli F, Knöll B. Neuroinflammation after Traumatic Brain Injury Is Enhanced in Activating Transcription Factor 3 Mutant Mice. J Neurotrauma 2018; 35:2317-2329. [PMID: 29463176 DOI: 10.1089/neu.2017.5593] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Traumatic brain injury (TBI) induces a neuroinflammatory response resulting in astrocyte and microglia activation at the lesion site. This involves upregulation of neuroinflammatory genes, including chemokines and interleukins. However, so far, there is lack of knowledge on transcription factors (TFs) modulating this TBI-associated gene expression response. Herein, we analyzed activating transcription factor 3 (ATF3), a TF encoding a regeneration-associated gene (RAG) predominantly studied in peripheral nervous system (PNS) injury. ATF3 contributes to PNS axon regeneration and was shown before to regulate inflammatory processes in other injury models. In contrast to PNS injury, data on ATF3 in central nervous system (CNS) injury are sparse. We used Atf3 mouse mutants and a closed-head weight-drop-based TBI model in adult mice to target the rostrolateral cortex resulting in moderate injury severity. Post-TBI, ATF3 was upregulated already at early time points (i.e,. 1-4 h) post-injury in the brain. Mortality and weight loss upon TBI were slightly elevated in Atf3 mutants. ATF3 deficiency enhanced TBI-induced paresis and hematoma formation, suggesting that ATF3 limits these injury outcomes in wild-type mice. Next, we analyzed TBI-associated RAG and inflammatory gene expression in the cortical impact area. In contrast to the PNS, only some RAGs (Atf3, Timp1, and Sprr1a) were induced by TBI, and, surprisingly, some RAG encoding neuropeptides were downregulated. Notably, we identified ATF3 as TF-regulating proneuroinflammatory gene expression, including CCL and CXCL chemokines (Ccl2, Ccl3, Ccl4, and Cxcl1) and lipocalin. In Atf3 mutant mice, mRNA abundance was further enhanced upon TBI compared to wild-type mice, suggesting immune gene repression by wild-type ATF3. In accord, more immune cells were present in the lesion area of ATF3-deficient mice. Overall, we identified ATF3 as a new TF-mediating TBI-associated CNS inflammatory responses.
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Affiliation(s)
- Philip Förstner
- 1 Institute of Physiological Chemistry, Ulm University , Ulm, Germany
| | - Rida Rehman
- 2 Department of Neurology, Ulm University , Ulm, Germany .,3 Department of Biomedical Engineering and Sciences (BMES), School of Mechanical and Manufacturing Engineering (SMME), National University of Sciences and Technology (NUST) , H-12, Islamabad, Pakistan
| | | | - Melanie Haffner-Luntzer
- 4 Institute of Orthopaedic Research and Biomechanics, Center for Trauma Research Ulm, University of Ulm , Ulm, Germany
| | - Daniela Sinske
- 1 Institute of Physiological Chemistry, Ulm University , Ulm, Germany
| | - Anita Ignatius
- 4 Institute of Orthopaedic Research and Biomechanics, Center for Trauma Research Ulm, University of Ulm , Ulm, Germany
| | | | - Bernd Knöll
- 1 Institute of Physiological Chemistry, Ulm University , Ulm, Germany
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Attwell CL, van Zwieten M, Verhaagen J, Mason MRJ. The Dorsal Column Lesion Model of Spinal Cord Injury and Its Use in Deciphering the Neuron-Intrinsic Injury Response. Dev Neurobiol 2018; 78:926-951. [PMID: 29717546 PMCID: PMC6221129 DOI: 10.1002/dneu.22601] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 04/03/2018] [Accepted: 04/05/2018] [Indexed: 12/13/2022]
Abstract
The neuron‐intrinsic response to axonal injury differs markedly between neurons of the peripheral and central nervous system. Following a peripheral lesion, a robust axonal growth program is initiated, whereas neurons of the central nervous system do not mount an effective regenerative response. Increasing the neuron‐intrinsic regenerative response would therefore be one way to promote axonal regeneration in the injured central nervous system. The large‐diameter sensory neurons located in the dorsal root ganglia are pseudo‐unipolar neurons that project one axon branch into the spinal cord, and, via the dorsal column to the brain stem, and a peripheral process to the muscles and skin. Dorsal root ganglion neurons are ideally suited to study the neuron‐intrinsic injury response because they exhibit a successful growth response following peripheral axotomy, while they fail to do so after a lesion of the central branch in the dorsal column. The dorsal column injury model allows the neuron‐intrinsic regeneration response to be studied in the context of a spinal cord injury. Here we will discuss the advantages and disadvantages of this model. We describe the surgical methods used to implement a lesion of the ascending fibers, the anatomy of the sensory afferent pathways and anatomical, electrophysiological, and behavioral techniques to quantify regeneration and functional recovery. Subsequently we review the results of experimental interventions in the dorsal column lesion model, with an emphasis on the molecular mechanisms that govern the neuron‐intrinsic injury response and manipulations of these after central axotomy. Finally, we highlight a number of recent advances that will have an impact on the design of future studies in this spinal cord injury model, including the continued development of adeno‐associated viral vectors likely to improve the genetic manipulation of dorsal root ganglion neurons and the use of tissue clearing techniques enabling 3D reconstruction of regenerating axon tracts. © 2018 The Authors. Developmental Neurobiology Published by Wiley Periodicals, Inc. Develop Neurobiol 00: 000–000, 2018
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Affiliation(s)
- Callan L Attwell
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands
| | - Mike van Zwieten
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands
| | - Joost Verhaagen
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands.,Center for Neurogenomics and Cognitive Research, Vrije Universiteit Amsterdam, De Boelelaan 1085, Amsterdam, 1081HV, The Netherlands
| | - Matthew R J Mason
- Laboratory for Regeneration of Sensorimotor Systems, Netherlands Institute for Neuroscience, an Institute of the Royal Netherlands Academy of Arts and Science, Meibergdreef 47, Amsterdam, 1105BA, The Netherlands
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Gey M, Wanner R, Schilling C, Pedro MT, Sinske D, Knöll B. Atf3 mutant mice show reduced axon regeneration and impaired regeneration-associated gene induction after peripheral nerve injury. Open Biol 2017; 6:rsob.160091. [PMID: 27581653 PMCID: PMC5008009 DOI: 10.1098/rsob.160091] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/01/2016] [Indexed: 12/27/2022] Open
Abstract
Axon injury in the peripheral nervous system (PNS) induces a regeneration-associated gene (RAG) response. Atf3 (activating transcription factor 3) is such a RAG and ATF3's transcriptional activity might induce ‘effector’ RAGs (e.g. small proline rich protein 1a (Sprr1a), Galanin (Gal), growth-associated protein 43 (Gap43)) facilitating peripheral axon regeneration. We provide a first analysis of Atf3 mouse mutants in peripheral nerve regeneration. In Atf3 mutant mice, facial nerve regeneration and neurite outgrowth of adult ATF3-deficient primary dorsal root ganglia neurons was decreased. Using genome-wide transcriptomics, we identified a neuropeptide-encoding RAG cluster (vasoactive intestinal peptide (Vip), Ngf, Grp, Gal, Pacap) regulated by ATF3. Exogenous administration of neuropeptides enhanced neurite growth of Atf3 mutant mice suggesting that these molecules might be effector RAGs of ATF3's pro-regenerative function. In addition to the induction of growth-promoting molecules, we present data that ATF3 suppresses growth-inhibiting molecules such as chemokine (C-C motif) ligand 2. In summary, we show a pro-regenerative ATF3 function during PNS nerve regeneration involving transcriptional activation of a neuropeptide-encoding RAG cluster. ATF3 is a general injury-inducible factor, therefore ATF3-mediated mechanisms identified herein might apply to other cell and injury types.
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Affiliation(s)
- Manuel Gey
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Renate Wanner
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Corinna Schilling
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - Maria T Pedro
- Department of Neurosurgery, Bezirkskrankenhaus Günzburg, Ulm University, 89081 Ulm, Germany
| | - Daniela Sinske
- 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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Holahan MR. A Shift from a Pivotal to Supporting Role for the Growth-Associated Protein (GAP-43) in the Coordination of Axonal Structural and Functional Plasticity. Front Cell Neurosci 2017; 11:266. [PMID: 28912688 PMCID: PMC5583208 DOI: 10.3389/fncel.2017.00266] [Citation(s) in RCA: 111] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 08/18/2017] [Indexed: 11/14/2022] Open
Abstract
In a number of animal species, the growth-associated protein (GAP), GAP-43 (aka: F1, neuromodulin, B-50, G50, pp46), has been implicated in the regulation of presynaptic vesicular function and axonal growth and plasticity via its own biochemical properties and interactions with a number of other presynaptic proteins. Changes in the expression of GAP-43 mRNA or distribution of the protein coincide with axonal outgrowth as a consequence of neuronal damage and presynaptic rearrangement that would occur following instances of elevated patterned neural activity including memory formation and development. While functional enhancement in GAP-43 mRNA and/or protein activity has historically been hypothesized as a central mediator of axonal neuroplastic and regenerative responses in the central nervous system, it does not appear to be the crucial substrate sufficient for driving these responses. This review explores the historical discovery of GAP-43 (and associated monikers), its transcriptional, post-transcriptional and post-translational regulation and current understanding of protein interactions and regulation with respect to its role in axonal function. While GAP-43 itself appears to have moved from a pivotal to a supporting factor, there is no doubt that investigations into its functions have provided a clearer understanding of the biochemical underpinnings of axonal plasticity.
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Functional and Molecular Characterization of a Novel Traumatic Peripheral Nerve–Muscle Injury Model. Neuromolecular Med 2017; 19:357-374. [DOI: 10.1007/s12017-017-8450-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 07/01/2017] [Indexed: 10/19/2022]
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Gordon T, Borschel GH. The use of the rat as a model for studying peripheral nerve regeneration and sprouting after complete and partial nerve injuries. Exp Neurol 2017; 287:331-347. [DOI: 10.1016/j.expneurol.2016.01.014] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/14/2016] [Accepted: 01/15/2016] [Indexed: 02/06/2023]
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Selecting optimal combinations of transcription factors to promote axon regeneration: Why mechanisms matter. Neurosci Lett 2016; 652:64-73. [PMID: 28025113 DOI: 10.1016/j.neulet.2016.12.032] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 12/02/2016] [Accepted: 12/14/2016] [Indexed: 01/17/2023]
Abstract
Recovery from injuries to the central nervous system, including spinal cord injury, is constrained in part by the intrinsically low ability of many CNS neurons to mount an effective regenerative growth response. To improve outcomes, it is essential to understand and ultimately reverse these neuron-intrinsic constraints. Genetic manipulation of key transcription factors (TFs), which act to orchestrate production of multiple regeneration-associated genes, has emerged as a promising strategy. It is likely that no single TF will be sufficient to fully restore neuron-intrinsic growth potential, and that multiple, functionally interacting factors will be needed. An extensive literature, mostly from non-neural cell types, has identified potential mechanisms by which TFs can functionally synergize. Here we examine four potential mechanisms of TF/TF interaction; physical interaction, transcriptional cross-regulation, signaling-based cross regulation, and co-occupancy of regulatory DNA. For each mechanism, we consider how existing knowledge can be used to guide the discovery and effective use of TF combinations in the context of regenerative neuroscience. This mechanistic insight into TF interactions is needed to accelerate the design of effective TF-based interventions to relieve neuron-intrinsic constraints to regeneration and to foster recovery from CNS injury.
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Wang Z, Winsor K, Nienhaus C, Hess E, Blackmore MG. Combined chondroitinase and KLF7 expression reduce net retraction of sensory and CST axons from sites of spinal injury. Neurobiol Dis 2016; 99:24-35. [PMID: 27988344 DOI: 10.1016/j.nbd.2016.12.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 12/02/2016] [Accepted: 12/13/2016] [Indexed: 11/26/2022] Open
Abstract
Axon regeneration in the central nervous system is limited both by inhibitory extracellular cues and by an intrinsically low capacity for axon growth in some CNS populations. Chondroitin sulfate proteoglycans (CSPGs) are well-studied inhibitors of axon growth in the CNS, and degradation of CSPGs by chondroitinase has been shown to improve the extension of injured axons. Alternatively, axon growth can be improved by targeting the neuron-intrinsic growth capacity through forced expression of regeneration-associated transcription factors. For example, a transcriptionally active chimera of Krüppel-like Factor 7 (KLF7) and a VP16 domain improves axon growth when expressed in corticospinal tract neurons. Here we tested the hypothesis that combined expression of chondroitinase and VP16-KLF7 would lead to further improvements in axon growth after spinal injury. Chondroitinase was expressed by viral transduction of cells in the spinal cord, while VP16-KLF7 was virally expressed in sensory neurons of the dorsal root ganglia or corticospinal tract (CST) neurons. After transection of the dorsal columns, both chondroitinase and VP16-KLF7 increased the proximity of severed sensory axons to the injury site. Similarly, after complete crush injuries, VP16-KLF7 expression increased the approach of CST axons to the injury site. In neither paradigm however, did single or combined treatment with chondroitinase or VP16-KLF7 enable regenerative growth distal to the injury. These results substantiate a role for CSPG inhibition and low KLF7 activity in determining the net retraction of axons from sites of spinal injury, while suggesting that additional factors act to limit a full regenerative response.
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Affiliation(s)
- Zimei Wang
- Department of Biomedical Sciences, Marquette University, 53201, USA
| | - Kristen Winsor
- Department of Biomedical Sciences, Marquette University, 53201, USA
| | | | - Evan Hess
- Department of Biomedical Sciences, Marquette University, 53201, USA
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Venkatesh I, Simpson MT, Coley DM, Blackmore MG. Epigenetic profiling reveals a developmental decrease in promoter accessibility during cortical maturation in vivo. NEUROEPIGENETICS 2016; 8:19-26. [PMID: 27990351 PMCID: PMC5159751 DOI: 10.1016/j.nepig.2016.10.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Axon regeneration in adult central nervous system (CNS) is limited in part by a developmental decline in the ability of injured neurons to re-express needed regeneration associated genes (RAGs). Adult CNS neurons may lack appropriate pro-regenerative transcription factors, or may display chromatin structure that restricts transcriptional access to RAGs. Here we performed epigenetic profiling around the promoter regions of key RAGs, and found progressive restriction across a time course of cortical maturation. These data identify a potential intrinsic constraint to axon growth in adult CNS neurons. Neurite outgrowth from cultured postnatal cortical neurons, however, proved insensitive to treatments that improve axon growth in other cell types, including combinatorial overexpression of AP1 factors, overexpression of histone acetyltransferases, and pharmacological inhibitors of histone deacetylases. This insensitivity could be due to intermediate chromatin closure at the time of culture, and highlights important differences in cell culture models used to test potential pro-regenerative interventions.
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Affiliation(s)
| | | | - Denise M. Coley
- Department of Biomedical Sciences, Marquette University, 53201
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31
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Chen J, Laramore C, Shifman MI. Differential expression of HDACs and KATs in high and low regeneration capacity neurons during spinal cord regeneration. Exp Neurol 2016; 280:50-9. [DOI: 10.1016/j.expneurol.2016.04.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 03/11/2016] [Accepted: 04/03/2016] [Indexed: 12/12/2022]
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32
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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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Chen J, Shifman MI. The expression of histone deacetylases and the regenerative abilities of spinal-projecting neurons after injury. Neural Regen Res 2016; 11:1577-1578. [PMID: 27904485 PMCID: PMC5116833 DOI: 10.4103/1673-5374.193233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Jie Chen
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA
| | - Michael I Shifman
- Shriners Hospitals Pediatric Research Center (Center for Neural Repair and Rehabilitation), Temple University School of Medicine, Philadelphia, PA, USA; Department of Neuroscience, Temple University School of Medicine, Philadelphia, PA, USA
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Integrated analyses of zebrafish miRNA and mRNA expression profiles identify miR-29b and miR-223 as potential regulators of optic nerve regeneration. BMC Genomics 2015; 16:591. [PMID: 26265132 PMCID: PMC4534052 DOI: 10.1186/s12864-015-1772-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 07/14/2015] [Indexed: 12/27/2022] Open
Abstract
Background Unlike mammals, zebrafish have the ability to regenerate damaged parts of their central nervous system (CNS) and regain functionality of the affected area. A better understanding of the molecular mechanisms involved in zebrafish regeneration may therefore provide insight into how CNS repair might be induced in mammals. Although many studies have described differences in gene expression in zebrafish during CNS regeneration, the regulatory mechanisms underpinning the differential expression of these genes have not been examined. Results We used microarrays to analyse and integrate the mRNA and microRNA (miRNA) expression profiles of zebrafish retina after optic nerve crush to identify potential regulatory mechanisms that underpin central nerve regeneration. Bioinformatic analysis identified 3 miRNAs and 657 mRNAs that were differentially expressed after injury. We then combined inverse correlations between our miRNA expression and mRNA expression, and integrated these findings with target predictions from TargetScan Fish to identify putative miRNA-gene target pairs. We focused on two over-expressed miRNAs (miR-29b and miR-223), and functionally validated seven of their predicted gene targets using RT-qPCR and luciferase assays to confirm miRNA-mRNA binding. Gene ontology analysis placed the miRNA-regulated genes (eva1a, layna, nefmb, ina, si:ch211-51a6.2, smoc1, sb:cb252) in key biological processes that included cell survival/apoptosis, ECM-cytoskeleton signaling, and heparan sulfate proteoglycan binding, Conclusion Our results suggest a key role for miR-29b and miR-223 in zebrafish regeneration. The identification of miRNA regulation in a zebrafish injury model provides a framework for future studies in which to investigate not only the cellular processes required for CNS regeneration, but also how these mechanisms might be regulated to promote successful repair and return of function in the injured mammalian brain. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1772-1) contains supplementary material, which is available to authorized users.
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Ma TC, Willis DE. What makes a RAG regeneration associated? Front Mol Neurosci 2015; 8:43. [PMID: 26300725 PMCID: PMC4528284 DOI: 10.3389/fnmol.2015.00043] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 07/24/2015] [Indexed: 12/31/2022] Open
Abstract
Regenerative failure remains a significant barrier for functional recovery after central nervous system (CNS) injury. As such, understanding the physiological processes that regulate axon regeneration is a central focus of regenerative medicine. Studying the gene transcription responses to axon injury of regeneration competent neurons, such as those of the peripheral nervous system (PNS), has provided insight into the genes associated with regeneration. Though several individual “regeneration-associated genes” (RAGs) have been identified from these studies, the response to injury likely regulates the expression of functionally coordinated and complementary gene groups. For instance, successful regeneration would require the induction of genes that drive the intrinsic growth capacity of neurons, while simultaneously downregulating the genes that convey environmental inhibitory cues. Thus, this view emphasizes the transcriptional regulation of gene “programs” that contribute to the overall goal of axonal regeneration. Here, we review the known RAGs, focusing on how their transcriptional regulation can reveal the underlying gene programs that drive a regenerative phenotype. Finally, we will discuss paradigms under which we can determine whether these genes are injury-associated, or indeed necessary for regeneration.
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Affiliation(s)
- Thong C Ma
- Department of Neurology, Columbia University New York, NY, USA
| | - Dianna E Willis
- Brain Mind Research Institute, Weill Cornell Medical College New York, NY, USA ; Burke-Cornell Medical Research Institute White Plains, NY, USA
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van der Kallen LR, Eggers R, Ehlert EM, Verhaagen J, Smit AB, van Kesteren RE. Genetic Deletion of the Transcriptional Repressor NFIL3 Enhances Axon Growth In Vitro but Not Axonal Repair In Vivo. PLoS One 2015; 10:e0127163. [PMID: 25993115 PMCID: PMC4438979 DOI: 10.1371/journal.pone.0127163] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 04/13/2015] [Indexed: 01/04/2023] Open
Abstract
Axonal regeneration after injury requires the coordinated expression of genes in injured neurons. We previously showed that either reducing expression or blocking function of the transcriptional repressor NFIL3 activates transcription of regeneration-associated genes Arg1 and Gap43 and strongly promotes axon outgrowth in vitro. Here we tested whether genetic deletion or dominant-negative inhibition of NFIL3 could promote axon regeneration and functional recovery after peripheral nerve lesion in vivo. Contrary to our expectations, we observed no changes in the expression of regeneration-associated genes and a significant delay in functional recovery following genetic deletion of Nfil3. When NFIL3 function was inhibited specifically in dorsal root ganglia prior to sciatic nerve injury, we observed a decrease in regenerative axon growth into the distal nerve segment rather than an increase. Finally, we show that deletion of Nfil3 changes sciatic nerve lesion-induced expression in dorsal root ganglia of genes that are not typically involved in regeneration, including several olfactory receptors and developmental transcription factors. Together our findings show that removal of NFIL3 in vivo does not recapitulate the regeneration-promoting effects that were previously observed in vitro, indicating that in vivo transcriptional control of regeneration is probably more complex and more robust against perturbation than in vitro data may suggest.
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Affiliation(s)
- Loek R. van der Kallen
- Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Ruben Eggers
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Erich M. Ehlert
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - Joost Verhaagen
- Department of Neuroregeneration, Netherlands Institute for Neuroscience, Amsterdam, The Netherlands
| | - August B. Smit
- Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
| | - Ronald E. van Kesteren
- Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, Amsterdam, The Netherlands
- * E-mail:
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Gordon T, You S, Cassar SL, Tetzlaff W. Reduced expression of regeneration associated genes in chronically axotomized facial motoneurons. Exp Neurol 2014; 264:26-32. [PMID: 25446720 DOI: 10.1016/j.expneurol.2014.10.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 09/15/2014] [Accepted: 10/29/2014] [Indexed: 12/24/2022]
Abstract
Chronically axotomized motoneurons progressively fail to regenerate their axons. Since axonal regeneration is associated with the increased expression of tubulin, actin and GAP-43, we examined whether the regenerative failure is due to failure of chronically axotomized motoneurons to express and sustain the expression of these regeneration associated genes (RAGs). Chronically axotomized facial motoneurons were subjected to a second axotomy to mimic the clinical surgical procedure of refreshing the proximal nerve stump prior to nerve repair. Expression of α1-tubulin, actin and GAP-43 was analyzed in axotomized motoneurons using in situ hybridization followed by autoradiography and silver grain quantification. The expression of these RAGs by acutely axotomized motoneurons declined over several months. The chronically injured motoneurons responded to a refreshment axotomy with a re-increase in RAG expression. However, this response to a refreshment axotomy of chronically injured facial motoneurons was less than that seen in acutely axotomized facial motoneurons. These data demonstrate that the neuronal RAG expression can be induced by injury-related signals and does not require acute deprivation of target derived factors. The transient expression is consistent with a transient inflammatory response to the injury. We conclude that transient RAG expression in chronically axotomized motoneurons and the weak response of the chronically axotomized motoneurons to a refreshment axotomy provides a plausible explanation for the progressive decline in regenerative capacity of chronically axotomized motoneurons.
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Affiliation(s)
- T Gordon
- Department of Neuroscience, University of Alberta, Edmonton, AB T6G 2S2, Canada; ICORD (International Collaboration on Repair Discoveries), Canada; Department Zoology, University of British Columbia, Vancouver, V5Z 1M9, BC, Canada; Department Surgery, University of British Columbia, Vancouver, BC, Canada.
| | - S You
- Department of Neuroscience, University of Alberta, Edmonton, AB T6G 2S2, Canada; ICORD (International Collaboration on Repair Discoveries), Canada; Department Zoology, University of British Columbia, Vancouver, V5Z 1M9, BC, Canada; Department Surgery, University of British Columbia, Vancouver, BC, Canada
| | - S L Cassar
- Department of Neuroscience, University of Alberta, Edmonton, AB T6G 2S2, Canada; ICORD (International Collaboration on Repair Discoveries), Canada; Department Zoology, University of British Columbia, Vancouver, V5Z 1M9, BC, Canada; Department Surgery, University of British Columbia, Vancouver, BC, Canada
| | - W Tetzlaff
- Department of Neuroscience, University of Alberta, Edmonton, AB T6G 2S2, Canada; ICORD (International Collaboration on Repair Discoveries), Canada; Department Zoology, University of British Columbia, Vancouver, V5Z 1M9, BC, Canada; Department Surgery, University of British Columbia, Vancouver, BC, Canada.
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Fagoe ND, van Heest J, Verhaagen J. Spinal cord injury and the neuron-intrinsic regeneration-associated gene program. Neuromolecular Med 2014; 16:799-813. [PMID: 25269879 DOI: 10.1007/s12017-014-8329-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 09/20/2014] [Indexed: 12/14/2022]
Abstract
Spinal cord injury (SCI) affects millions of people worldwide and causes a significant physical, emotional, social and economic burden. The main clinical hallmark of SCI is the permanent loss of motor, sensory and autonomic function below the level of injury. In general, neurons of the central nervous system (CNS) are incapable of regeneration, whereas injury to the peripheral nervous system is followed by axonal regeneration and usually results in some degree of functional recovery. The weak neuron-intrinsic regeneration-associated gene (RAG) response upon injury is an important reason for the failure of neurons in the CNS to regenerate an axon. This response consists of the expression of many RAGs, including regeneration-associated transcription factors (TFs). Regeneration-associated TFs are potential key regulators of the RAG program. The function of some regeneration-associated TFs has been studied in transgenic and knock-out mice and by adeno-associated viral vector-mediated overexpression in injured neurons. Here, we review these studies and propose that AAV-mediated gene delivery of combinations of regeneration-associated TFs is a potential strategy to activate the RAG program in injured CNS neurons and achieve long-distance axon regeneration.
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Affiliation(s)
- Nitish D Fagoe
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, 1105 BA, Amsterdam, The Netherlands,
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Abstract
Axon regeneration is hindered by a decline of intrinsic axon growth capability in mature neurons. Reversing this decline is associated with the induction of a large repertoire of regeneration-associated genes (RAGs), but the underlying regulatory mechanisms of the transcriptional changes are largely unknown. Here, we establish a correlation between diminished axon growth potential and histone 4 (H4) hypoacetylation. When neurons are triggered into a growth state, as in the conditioning lesion paradigm, H4 acetylation is restored, and RAG transcription is initiated. We have identified a set of target genes of Smad1, a proregenerative transcription factor, in conditioned DRG neurons. We also show that, during the epigenetic reprogramming process, histone-modifying enzymes work together with Smad1 to facilitate transcriptional regulation of RAGs. Importantly, targeted pharmacological modulation of the activity of histone-modifying enzymes, such as histone deacetylases, leads to induction of multiple RAGs and promotion of sensory axon regeneration in a mouse model of spinal cord injury. Our findings suggest epigenetic modulation as a potential therapeutic strategy to enhance axon regeneration.
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Huang Z, Ha G, Petitto J. Reversal of Neuronal Atrophy: Role of Cellular Immunity in Neuroplasticity and Aging. ACTA ACUST UNITED AC 2014; 2. [PMID: 25505790 DOI: 10.4172/2329-6895.1000170] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Emerging evidence indicates that neuroimmunological changes in the brain can modify intrinsic brain processes that are involved in regulating neuroplasticity. Increasing evidence suggests that in some forms of motor neuron injury, many neurons do not die, but reside in an atrophic state for an extended period of time. In mice, facial motor neurons in the brain undergo a protracted period of degeneration or atrophy following resection of their peripheral axons. Reinjuring the proximal nerve stump of the chronically resected facial nerve stimulates a robust reversal of motor neuron atrophy which results in marked increases in both the number and size of injured motor neurons in the facial motor nucleus. In this brief review, we describe research from our lab which indicates that the reversal of atrophy in this injury model is dependent on normal cellular immunity. The role of T cells in this unique form of neuroplasticity following injury and in brain aging, are discussed. The potential role of yet undiscover intrinsic actions of recombination activating genes in the brain are considered. Further research using the facial nerve reinjury model could identify molecular signals involved in neuroplasticity, and lead to new ways to stimulate neuroregenerative processes in neurotrauma and other forms of brain insult and disease.
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Affiliation(s)
- Zhi Huang
- Departments of Neuroscience and Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL, USA
| | - Grace Ha
- Departments of Neuroscience and Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL, USA
| | - John Petitto
- Departments of Neuroscience and Psychiatry, McKnight Brain Institute, University of Florida, Gainesville, FL, USA
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de Winter F, Hoyng S, Tannemaat M, Eggers R, Mason M, Malessy M, Verhaagen J. Gene therapy approaches to enhance regeneration of the injured peripheral nerve. Eur J Pharmacol 2013; 719:145-152. [DOI: 10.1016/j.ejphar.2013.04.057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 01/26/2023]
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Saijilafu, Zhang BY, Zhou FQ. Signaling pathways that regulate axon regeneration. Neurosci Bull 2013; 29:411-20. [PMID: 23846598 DOI: 10.1007/s12264-013-1357-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2012] [Accepted: 02/25/2013] [Indexed: 10/26/2022] Open
Abstract
Neurons in the mammalian central nervous system (CNS) cannot regenerate axons after injury. in contrast, neurons in the mammalian peripheral nervous system and in some non-mammalian models, such as C. elegans and Drosophila, are able to regrow axons. Understanding the molecular mechanisms by which these neurons support axon regeneration will help us find ways to enhance mammalian CNS axon regeneration. Here, recent studies in which signaling pathways regulating naturally-occurring axon regeneration that have been identified are reviewed, focusing on how these pathways control gene expression and growth-cone function during axon regeneration.
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Affiliation(s)
- Saijilafu
- Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland, USA
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Huang Z, Ha GK, Petitto JM. 5. T cell immunity and neuroplasticity. RECENT RESEARCH DEVELOPMENTS IN NEUROSCIENCE 2013; 4:109-119. [PMID: 25599095 PMCID: PMC4295499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The proneuronal effects of T cells that impact the brain occur from both T cells trafficking into the brain, and from signals in the periphery (e.g., cytokine release and regulation). Recent data indicates that neuroimmunological changes in the brain can modify intrinsic brain processes that are involved in regulating neuroplasticity (e.g., T-cell/microglial interactions, neurotrophins, neurogenesis). We describe: 1) work from our lab and others showing that injury-induced loss of neuronal phenotype and reversal of motor neuron atrophy are associated with normal T cell immunity, and; 2) research indicating that these and other neuroimmunological processes may be generalizable to mechanisms of neuroplasticity involved in cognitive and emotional behavior. These findings are discussed in relation to our lab's working hypothesis, that T cell immunosenesence may contribute to alterations in brain neuroplasticity related to aging. Greater understanding of the role of adaptive T cell immunity on neuroplasticity could have important clinical implications for developing novel treatment strategies for neurodegenerative diseases (e.g., Alzheimer's) and brain injury (e.g., stroke, trauma).
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FGF-2 Low Molecular Weight Selectively Promotes Neuritogenesis of Motor Neurons In Vitro. Mol Neurobiol 2012; 47:770-81. [DOI: 10.1007/s12035-012-8389-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2012] [Accepted: 12/14/2012] [Indexed: 01/31/2023]
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Tedeschi A. Tuning the orchestra: transcriptional pathways controlling axon regeneration. Front Mol Neurosci 2012; 4:60. [PMID: 22294979 PMCID: PMC3257844 DOI: 10.3389/fnmol.2011.00060] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Accepted: 12/23/2011] [Indexed: 12/13/2022] Open
Abstract
Trauma in the adult mammalian central nervous system leads to irreversible structural and functional impairment due to failed regeneration attempts. In contrast, neurons in the peripheral nervous system exhibit a greater regenerative ability. It has been proposed that an orchestrated sequence of transcriptional events controlling the expression of specific sets of genes may be the underlying basis of an early cell-autonomous regenerative response. Understanding whether transcriptional fine tuning, in parallel with strategies aimed at counteracting extrinsic impediments promotes axon re-growth following central nervous system injuries represents an exciting challenge for future studies. Transcriptional pathways controlling axon regeneration are presented and discussed in this review.
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Affiliation(s)
- Andrea Tedeschi
- Department of Neurology, F. M. Kirby Neurobiology Center, Children's Hospital Boston Boston, MA, USA
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