1
|
Lear BP, Moore DL. Moving CNS axon growth and regeneration research into human model systems. Front Neurosci 2023; 17:1198041. [PMID: 37425013 PMCID: PMC10324669 DOI: 10.3389/fnins.2023.1198041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 05/25/2023] [Indexed: 07/11/2023] Open
Abstract
Axon regeneration is limited in the adult mammalian central nervous system (CNS) due to both intrinsic and extrinsic factors. Rodent studies have shown that developmental age can drive differences in intrinsic axon growth ability, such that embryonic rodent CNS neurons extend long axons while postnatal and adult CNS neurons do not. In recent decades, scientists have identified several intrinsic developmental regulators in rodents that modulate growth. However, whether this developmentally programmed decline in CNS axon growth is conserved in humans is not yet known. Until recently, there have been limited human neuronal model systems, and even fewer age-specific human models. Human in vitro models range from pluripotent stem cell-derived neurons to directly reprogrammed (transdifferentiated) neurons derived from human somatic cells. In this review, we discuss the advantages and disadvantages of each system, and how studying axon growth in human neurons can provide species-specific knowledge in the field of CNS axon regeneration with the goal of bridging basic science studies to clinical trials. Additionally, with the increased availability and quality of 'omics datasets of human cortical tissue across development and lifespan, scientists can mine these datasets for developmentally regulated pathways and genes. As there has been little research performed in human neurons to study modulators of axon growth, here we provide a summary of approaches to begin to shift the field of CNS axon growth and regeneration into human model systems to uncover novel drivers of axon growth.
Collapse
Affiliation(s)
| | - Darcie L. Moore
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, United States
| |
Collapse
|
2
|
Girouard MP, Simas T, Hua L, Morquette B, Khazaei MR, Unsain N, Johnstone AD, Rambaldi I, Sanz RL, Di Raddo ME, Gamage KK, Yong Y, Willis DE, Verge VMK, Barker PA, Deppmann C, Fournier AE. Collapsin Response Mediator Protein 4 (CRMP4) Facilitates Wallerian Degeneration and Axon Regeneration following Sciatic Nerve Injury. eNeuro 2020; 7:ENEURO.0479-19.2020. [PMID: 32001550 PMCID: PMC7053045 DOI: 10.1523/eneuro.0479-19.2020] [Citation(s) in RCA: 4] [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: 11/18/2019] [Revised: 01/14/2020] [Accepted: 01/15/2020] [Indexed: 11/29/2022] Open
Abstract
In contrast to neurons in the CNS, damaged neurons from the peripheral nervous system (PNS) regenerate, but this process can be slow and imperfect. Successful regeneration is orchestrated by cytoskeletal reorganization at the tip of the proximal axon segment and cytoskeletal disassembly of the distal segment. Collapsin response mediator protein 4 (CRMP4) is a cytosolic phospho-protein that regulates the actin and microtubule cytoskeleton. During development, CRMP4 promotes growth cone formation and dendrite development. Paradoxically, in the adult CNS, CRMP4 impedes axon regeneration. Here, we investigated the involvement of CRMP4 in peripheral nerve injury in male and female Crmp4-/- mice following sciatic nerve injury. We find that sensory axon regeneration and Wallerian degeneration are impaired in Crmp4-/- mice following sciatic nerve injury. In vitro analysis of dissociated dorsal root ganglion (DRG) neurons from Crmp4-/- mice revealed that CRMP4 functions in the proximal axon segment to promote the regrowth of severed DRG neurons and in the distal axon segment where it facilitates Wallerian degeneration through calpain-dependent formation of harmful CRMP4 fragments. These findings reveal an interesting dual role for CRMP4 in proximal and distal axon segments of injured sensory neurons that coordinately facilitate PNS axon regeneration.
Collapse
Affiliation(s)
- Marie-Pier Girouard
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Tristan Simas
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Luyang Hua
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Barbara Morquette
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Mohamad R Khazaei
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Nicolas Unsain
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), 5016 Córdoba, Argentina
| | - Aaron D Johnstone
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Isabel Rambaldi
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | - Ricardo L Sanz
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| | | | - Kanchana K Gamage
- Department of Biology, University of Virginia, Charlottesville, Virginia 22903
| | - Yu Yong
- Department of Biology, University of Virginia, Charlottesville, Virginia 22903
| | - Dianna E Willis
- Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York 10065
- Burke Institute, Weill Cornell Medicine, White Plains, New York 10605
| | - Valerie M K Verge
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan-CMSNRC, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Philip A Barker
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
- Department of Biology, University of British Columbia, Kelowna, British Columbia V1V 1V7, Canada
| | | | - Alyson E Fournier
- Department of Neurology and Neurosurgery, Montréal Neurological Institute and Hospital, Montréal, Québec H3A 2B4, Canada
| |
Collapse
|
3
|
Ribas VT, Costa MR. Gene Manipulation Strategies to Identify Molecular Regulators of Axon Regeneration in the Central Nervous System. Front Cell Neurosci 2017; 11:231. [PMID: 28824380 PMCID: PMC5545589 DOI: 10.3389/fncel.2017.00231] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 07/24/2017] [Indexed: 01/08/2023] Open
Abstract
Limited axon regeneration in the injured adult mammalian central nervous system (CNS) usually results in irreversible functional deficits. Both the presence of extrinsic inhibitory molecules at the injury site and the intrinsically low capacity of adult neurons to grow axons are responsible for the diminished capacity of regeneration in the adult CNS. Conversely, in the embryonic CNS, neurons show a high regenerative capacity, mostly due to the expression of genes that positively control axon growth and downregulation of genes that inhibit axon growth. A better understanding of the role of these key genes controlling pro-regenerative mechanisms is pivotal to develop strategies to promote robust axon regeneration following adult CNS injury. Genetic manipulation techniques have been widely used to investigate the role of specific genes or a combination of different genes in axon regrowth. This review summarizes a myriad of studies that used genetic manipulations to promote axon growth in the injured CNS. We also review the roles of some of these genes during CNS development and suggest possible approaches to identify new candidate genes. Finally, we critically address the main advantages and pitfalls of gene-manipulation techniques, and discuss new strategies to promote robust axon regeneration in the mature CNS.
Collapse
Affiliation(s)
- Vinicius T Ribas
- Laboratory of Neurobiology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas GeraisBelo Horizonte, Brazil
| | - Marcos R Costa
- Brain Institute, Federal University of Rio Grande do NorteNatal, Brazil
| |
Collapse
|
4
|
O'Donovan KJ. Intrinsic Axonal Growth and the Drive for Regeneration. Front Neurosci 2016; 10:486. [PMID: 27833527 PMCID: PMC5081384 DOI: 10.3389/fnins.2016.00486] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 10/10/2016] [Indexed: 02/01/2023] Open
Abstract
Following damage to the adult nervous system in conditions like stroke, spinal cord injury, or traumatic brain injury, many neurons die and most of the remaining spared neurons fail to regenerate. Injured neurons fail to regrow both because of the inhibitory milieu in which they reside as well as a loss of the intrinsic growth capacity of the neurons. If we are to develop effective therapeutic interventions that promote functional recovery for the devastating injuries described above, we must not only better understand the molecular mechanisms of developmental axonal growth in hopes of re-activating these pathways in the adult, but at the same time be aware that re-activation of adult axonal growth may proceed via distinct mechanisms. With this knowledge in hand, promoting adult regeneration of central nervous system neurons can become a more tractable and realistic therapeutic endeavor.
Collapse
Affiliation(s)
- Kevin J O'Donovan
- Department of Chemistry and Life Science, United States Military Academy West Point, NY, USA
| |
Collapse
|
5
|
|
6
|
Yang J, Han Y, Ye W, Liu F, Zhuang K, Wu G. Alpha tocopherol treatment reduces the expression of Nogo-A and NgR in rat brain after traumatic brain injury. J Surg Res 2012. [PMID: 23207171 DOI: 10.1016/j.jss.2012.11.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Neurite outgrowth inhibitor-A (Nogo-A), myelin-associated glycoprotein, and oligodendrocyte myelin glycoprotein are three myelin-associated proteins that act as inhibitors to central nervous system regeneration. Neurite outgrowth inhibitor-A imposes the strongest effect on inhibiting axonal regeneration after traumatic brain injury. Alpha-tocopherol, a member of the vitamin E family, is recognized as an active antioxidative substance. Its use has not been well studied in brain injury research, especially in axonal regeneration research. METHODS We obtained 99 intact adult male Sprague-Dawley rats (200-250 g) from the Experimental Animal Center of Central South University. We used the modified method of Freeney to generate moderate brain injury in the rats. We injected 600 mg/kg α-tocopherol intraperitoneally daily as traumatic brain injury (TBI) treatment. Then, we performed behavioral tests in the corresponding time point, examined brain tissues after hematoxylin-eosin staining to identify changes in cell morphology, and performed immunohistochemical staining and quantitative real-time polymerase chain reaction to detect the expression of NoGo and Nogo receptor (NgR) in brain tissue. RESULTS For the Neurological Severity Scores of rats, there were obvious differences among the three groups at the corresponding time points. Standard hematoxylin-eosin staining showed that the brain structure of a sham-operated group of rats was clear, uniform, and compact. A TBI group exhibited hemorrhage, edema, inflammatory cell infiltration, condensed nuclei, and necrosis. We also saw glial cells and fibrous tissue proliferation. The α-tocopherol-treated TBI group had similar but less severe changes than the TBI group. Expression of Nogo-A and NgR increased after TBI compared with the sham-operated group. However, Nogo-A and NgR expression was significantly lower in the α-tocopherol-treated TBI group compared with the TBI group. Similarly, results showed that functional neurological deficits among rats in the α-tocopherol-treated TBI group were less pronounced than in the TBI group (model group). CONCLUSIONS Our data demonstrate that α-tocopherol-treated rats had reduced microscopic evidence of brain damage. Alpha-tocopherol reduced Nogo-A and NgR expression in brain tissue after traumatic brain injury and promoted nerve regeneration. Alpha-tocopherol treatment of TBI rats had a neuroprotective role in their recovery.
Collapse
Affiliation(s)
- Jinfu Yang
- Department of Neurosurgery, Third Xiangya Hospital of Central South University, Changsha, Hunan, China
| | | | | | | | | | | |
Collapse
|
7
|
Gu W, Zhang F, Xue Q, Ma Z, Lu P, Yu B. Bone mesenchymal stromal cells stimulate neurite outgrowth of spinal neurons by secreting neurotrophic factors. Neurol Res 2012; 34:172-80. [PMID: 22333032 DOI: 10.1179/1743132811y.0000000068] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
It has been demonstrated that bone mesenchymal stromal cells (BMSCs) stimulate neurite outgrowth from dorsal root ganglion (DRG) neurons. The present in vitro study tested the hypothesis that BMSCs stimulate the neurite outgrowth from spinal neurons by secreting neurotrophic factors. Spinal neurons were cocultured with BMSCs, fibroblasts and control medium in a non-contact system. Neurite outgrowth of spinal neurons cocultured with BMSCs was significantly greater than the neurite outgrowth observed in neurons cultured with control medium or with fibroblasts. In addition, BMSC-conditioned medium increased the length of neurites from spinal neurons compared to those of neurons cultured in the control medium or in the fibroblasts-conditioned medium. BMSCs expressed brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF). The concentrations of BDNF and GDNF in BMSC-conditioned medium were 132±12 and 70±6 pg ml(-1), respectively. The addition of anti-BDNF and anti-GDNF antibodies to BMSC-conditioned medium partially blocked the neurite-promoting effect of the BMSC-conditioned medium. In conclusion, our results demonstrate that BMSCs promote neurite outgrowth in spinal neurons by secreting soluble factors. The neurite-promoting effect of BMSCs is partially mediated by BDNF and GDNF.
Collapse
Affiliation(s)
- Weidong Gu
- Shanghai Minhang Central Hospital, Shanghai, China
| | | | | | | | | | | |
Collapse
|
8
|
Cell–Cell interactions of human neural progenitor-derived astrocytes within a microstructured 3D-scaffold. Biomaterials 2010; 31:7705-15. [DOI: 10.1016/j.biomaterials.2010.06.060] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 06/30/2010] [Indexed: 12/11/2022]
|
9
|
Arie Y, Iketani M, Takamatsu K, Mikoshiba K, Goshima Y, Takei K. Developmental changes in the regulation of calcium-dependent neurite outgrowth. Biochem Biophys Res Commun 2009; 379:11-5. [DOI: 10.1016/j.bbrc.2008.11.128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 11/23/2008] [Indexed: 10/21/2022]
|
10
|
Zurn AD, Bandtlow CE. Regeneration failure in the CNs: cellular and molecular mechanisms. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 557:54-76. [PMID: 16955704 DOI: 10.1007/0-387-30128-3_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Anne D Zurn
- Department of Experimental Surgery, Lausanne University Hospital, Faculty of Biology and Medicine, Switzerland
| | | |
Collapse
|
11
|
Raivich G, Makwana M. The making of successful axonal regeneration: Genes, molecules and signal transduction pathways. ACTA ACUST UNITED AC 2007; 53:287-311. [PMID: 17079020 DOI: 10.1016/j.brainresrev.2006.09.005] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Revised: 09/12/2006] [Accepted: 09/18/2006] [Indexed: 12/16/2022]
Abstract
Unlike its central counterpart, the peripheral nervous system is well known for its comparatively good potential for regeneration following nerve fiber injury. This ability is mirrored by the de novo expression or upregulation of a wide variety of molecules including transcription factors, growth-stimulating substances, cell adhesion molecules, intracellular signaling enzymes and proteins involved in regulating cell-surface cytoskeletal interactions, that promote neurite outgrowth in cultured neurons. However, their role in vivo is less known. Recent studies using neutralizing antibodies, gene inactivation and overexpression techniques have started to shed light on those endogenous molecules that play a key role in axonal outgrowth and the process of successful functional repair in the injured nervous system. The aim of the current review is to provide a summary on this rapidly growing field and the experimental techniques used to define the specific effects of candidate signaling molecules on axonal regeneration in vivo.
Collapse
Affiliation(s)
- Gennadij Raivich
- Perinatal Brain Repair Group, Department of Obstetrics and Gynaecology, University College London, 86-96 Chenies Mews, London, UK.
| | | |
Collapse
|
12
|
Iizuka A, Sengoku K, Iketani M, Nakamura F, Sato Y, Matsushita M, Nairn AC, Takamatsu K, Goshima Y, Takei K. Calcium-induced synergistic inhibition of a translational factor eEF2 in nerve growth cones. Biochem Biophys Res Commun 2007; 353:244-50. [PMID: 17187762 DOI: 10.1016/j.bbrc.2006.11.150] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 11/29/2006] [Indexed: 10/23/2022]
Abstract
Local protein synthesis in nerve growth cones has been suggested, but how it is controlled remains largely unknown. We found eukaryotic elongation factor-2 (eEF2), a key component of mRNA translation, in growth cones by immunocytochemistry. While phosphorylated eEF2 was weakly distributed in advancing growth cones, eEF2 phosphorylation was increased by high potassium-evoked calcium influx. In the growth cone, calcium elevation increased eEF2 kinase (EF2K), a calcim-calmodulin-dependent enzyme. Calcium also decreased the level of phosphorylated p70-S6 kinase (S6K), a kinase known to inhibit EF2K. Moreover, calcium elevation decreased total eEF2 in growth cones. Since phosphorylated eEF2 inhibits mRNA translation, calcium elevation appears to inhibit mRNA translation in growth cones by a synergistic mechanism involving regulation of EF2K, S6K, and eEF2 itself. Time-lapse imaging showed that calcium elevation induced growth arrest of neurites. The inhibitory effect on mRNA translation may thus be involved in the regulation of neurite outgrowth.
Collapse
Affiliation(s)
- Akira Iizuka
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University Graduate School of Medicine, Fuku-ura 3-9, Kanazawa Ward, Yokohama 236-0004, Japan
| | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Pizzi MA, Crowe MJ. Matrix metalloproteinases and proteoglycans in axonal regeneration. Exp Neurol 2006; 204:496-511. [PMID: 17254568 DOI: 10.1016/j.expneurol.2006.12.012] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2006] [Revised: 12/12/2006] [Accepted: 12/14/2006] [Indexed: 12/13/2022]
Abstract
After an injury to the adult mammalian central nervous system (CNS), a variety of growth-inhibitory molecules are upregulated. A glial scar forms at the site of injury and is composed of numerous molecular substances, including chondroitin sulfate proteoglycans (CSPGs). These proteoglycans inhibit axonal growth in vitro and in vivo. Matrix metalloproteinases (MMPs) can degrade the core protein of some CSPGs as well as other growth-inhibitory molecules such as Nogo and tenascin-C. MMPs have been shown to facilitate axonal regeneration in the adult mammalian peripheral nervous system (PNS). This review will focus on the various roles of proteoglycans and MMPs within the injured nervous system. First, we will present a general background on the injured central nervous system and explore the roles that proteoglycans play in the injured PNS and CNS. Second, we will discuss the various functions of MMPs within the injured PNS and CNS. Special attention will be paid to the possibility of how MMPs might modify the growth-inhibitory extracellular environment of the injured adult mammalian spinal cord and facilitate axonal regeneration in the CNS.
Collapse
Affiliation(s)
- Michael A Pizzi
- Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Zablocki VAMC, 5000 West National Avenue, Milwaukee, WI 53295, USA
| | | |
Collapse
|
14
|
Regeneration and Repair. Dev Neurobiol 2006. [DOI: 10.1007/0-387-28117-7_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
15
|
Schwab JM, Bernard F, Moreau-Fauvarque C, Chédotal A. Injury reactive myelin/oligodendrocyte-derived axon growth inhibition in the adult mammalian central nervous system. ACTA ACUST UNITED AC 2005; 49:295-9. [PMID: 16111557 DOI: 10.1016/j.brainresrev.2004.10.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Revised: 10/21/2004] [Accepted: 10/26/2004] [Indexed: 10/25/2022]
Abstract
Myelin inhibition is considered a constitutive, static, repulsive barrier not reactive to a central nervous system (CNS) lesion. However, recent evidence underlines the existence of considerable add-on axon growth inhibition upon CNS injury. This postlesional, reactive myelin/oligodendrocyte-derived inhibition will require the development of novel screening approaches and therapeutic reagents to promote axonal regeneration.
Collapse
Affiliation(s)
- Jan M Schwab
- CNRS UMR 7102, Equipe Développement Neuronal, Université Pierre et Marie Curie (Paris 6), Batiment B, Case 12, 9 Quai Saint Bernard, 75005 Paris, France
| | | | | | | |
Collapse
|
16
|
Schwab JM, Failli V, Chédotal A. Injury-related dynamic myelin/oligodendrocyte axon-outgrowth inhibition in the central nervous system. Lancet 2005; 365:2055-7. [PMID: 15950719 DOI: 10.1016/s0140-6736(05)66699-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
CONTEXT By contrast with the glial scar, myelin was considered a constitutive static inhibitory barrier unreactive to lesions in the central nervous system (CNS). However, recent results suggest considerable add-on inhibition of myelin as a result of CNS injury. Furthermore, catastrophic events cause morphological and biochemical changes in the axon itself. This results in the accumulation of cytoskeleton components and intraaxonal transported proteins paralleled by extensive membrane remodelling at the axonal tip (a process called axotomy) which might modify the axonal response to its inhibitory environment. STARTING POINT Ji-Eun Kim and colleagues recently reported an axonal subpopulation with a different capacity to respond to myelin inhibitors (Neuron 2004; 44: 439-51). Axonal specificity but also evidence for injury reactivity summarised here challenges our understanding of axon-growth inhibition in the injured CNS. This might be due to (i) qualitative and quantitative enrichment of the periaxonal environment by myelin/oligodendrocytes, (ii) increased axonal sensitivity to its inhibitory environment, and (iii) axons and lesion-induced, altered axonal signalling. WHERE NEXT? Postlesional reactive inhibition of myelin or the oligodendrocyte necessitates the development of novel screening approaches and therapeutic agents to promote axonal regeneration. Moreover, we need to improve our understanding of the pathophysiology of the lesion to find more efficient experimental strategies to restore neurological function.
Collapse
Affiliation(s)
- Jan M Schwab
- Equipe Développement Neuronal, CNRS UMR 7102, Université Pierre et Marie Curie (Paris 6), Paris, France.
| | | | | |
Collapse
|
17
|
Abstract
Neurons extend long axons and highly branched dendrites, and our understanding of the essential regulators of these processes has advanced in recent years. In the past year, investigators have shown that transcriptional control, posttranslational degradation and signaling cascades may be master regulators of axon and dendrite elongation and branching. Thus, evidence is mounting for the importance of the intrinsic growth state of a neuron as a crucial determinant of its ability to grow, or to regenerate, axons and dendrites.
Collapse
Affiliation(s)
- Jeffrey L Goldberg
- Department of Ophthalmology, McKnight Vision Research Center, Bascom Palmer Eye Institute, 1638 NW 10th Ave, Miami, Florida 33136, USA.
| |
Collapse
|
18
|
Mercado MLT, Nur-e-Kamal A, Liu HY, Gross SR, Movahed R, Meiners S. Neurite outgrowth by the alternatively spliced region of human tenascin-C is mediated by neuronal alpha7beta1 integrin. J Neurosci 2004; 24:238-47. [PMID: 14715956 PMCID: PMC6729556 DOI: 10.1523/jneurosci.4519-03.2004] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The region of tenascin-C containing only alternately spliced fibronectin type-III repeat D (fnD) increases neurite outgrowth by itself and also as part of tenascin-C. We previously localized the active site within fnD to an eight amino acid sequence unique to tenascin-C, VFDNFVLK, and showed that the amino acids FD and FV are required for activity. The purpose of this study was to identify the neuronal receptor that interacts with VFDNFVLK and to investigate the hypothesis that FD and FV are important for receptor binding. Function-blocking antibodies against both alpha7 and beta1 integrin subunits were found to abolish VFDNFVLK-mediated process extension from cerebellar granule neurons. VFDNFVLK but not its mutant, VSPNGSLK, induced clustering of neuronal beta1 integrin immunoreactivity. This strongly implicates FD and FV as important structural elements for receptor activation. Moreover, biochemical experiments revealed an association of the alpha7beta1 integrin with tenascin-C peptides containing the VFDNFVLK sequence but not with peptides with alterations in FD and/or FV. These findings are the first to provide evidence that the alpha7beta1 integrin mediates a response to tenascin-C and the first to demonstrate a functional role for the alpha7beta1 integrin receptor in CNS neurons.
Collapse
Affiliation(s)
- Mary Lynn T Mercado
- Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA
| | | | | | | | | | | |
Collapse
|
19
|
Huber AB, Kolodkin AL, Ginty DD, Cloutier JF. Signaling at the growth cone: ligand-receptor complexes and the control of axon growth and guidance. Annu Rev Neurosci 2003; 26:509-63. [PMID: 12677003 DOI: 10.1146/annurev.neuro.26.010302.081139] [Citation(s) in RCA: 562] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The guidance of axons during the establishment of the nervous system is mediated by a variety of extracellular cues that govern cytoskeletal dynamics in axonal growth cones. A large number of these guidance cues and their cell-surface receptors have now been identified, and the intracellular signaling pathways by which these cues induce cytoskeletal rearrangements are becoming defined. This review summarizes our current understanding of the major families of axon guidance cues and their receptors, with a particular emphasis on receptor signaling mechanisms. We also discuss recent advances in understanding receptor cross talk and how the activities of guidance cues and their receptors are modulated during neural development.
Collapse
Affiliation(s)
- Andrea B Huber
- Department of Neuroscience, Howard Hughes Medical Institute, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | | | | | | |
Collapse
|
20
|
Filbin MT. Myelin-associated inhibitors of axonal regeneration in the adult mammalian CNS. Nat Rev Neurosci 2003; 4:703-13. [PMID: 12951563 DOI: 10.1038/nrn1195] [Citation(s) in RCA: 636] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Marie T Filbin
- Department of Biological Sciences, Hunter College, City University of New York, 695 Park Avenue, New York, New York 10021, USA.
| |
Collapse
|
21
|
Schnaar RL. Myelin molecules limiting nervous system plasticity. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2003; 32:125-42. [PMID: 12827974 DOI: 10.1007/978-3-642-55557-2_6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- R L Schnaar
- Departments of Pharmacology and Neuroscience, Johns Hopkins School of Medicine, 725 N. Wolfe Street, Baltimore, Maryland 21205, USA
| |
Collapse
|
22
|
Abstract
Nogo-A is a potent neurite growth inhibitor in vitro and plays a role both in the restriction of axonal regeneration after injury and in structural plasticity in the CNS of higher vertebrates. The regions that mediate inhibition and the topology of the molecule in the plasma membrane have to be defined. Here we demonstrate the presence of three different active sites: (1) an N-terminal region involved in the inhibition of fibroblast spreading, (2) a stretch encoded by the Nogo-A-specific exon that restricts neurite outgrowth and cell spreading and induces growth cone collapse, and (3) a C-terminal region (Nogo-66) with growth cone collapsing function. We show that Nogo-A-specific active fragments bind to the cell surface of responsive cells and to rat brain cortical membranes, suggesting the existence of specific binding partners or receptors. Several antibodies against different epitopes on the Nogo-A-specific part of the protein as well as antisera against the 66 aa loop in the C-terminus stain the cell surface of living cultured oligodendrocytes. Nogo-A is also labeled by nonmembrane-permeable biotin derivatives applied to living oligodendrocyte cultures. Immunofluorescent staining of intracellular, endoplasmic reticulum-associated Nogo-A in cells after selective permeabilization of the plasma membrane reveals that the epitopes of Nogo-A, shown to be accessible at the cell surface, are exposed to the cytoplasm. This suggests that Nogo-A could have a second membrane topology. The two proposed topological variants may have different intracellular as well as extracellular functions.
Collapse
|
23
|
Affiliation(s)
- Jeffrey L Goldberg
- Department of Neurobiology, Stanford University School of Medicine, California 94305, USA.
| |
Collapse
|
24
|
Abstract
Neuritogenesis and its inhibition are opposite and balancing processes during development as well as pathological states of adult neuron. In particular, the inability of adult central nervous system (CNS) neurons to regenerate upon injury has been attributed to both a lack of neuritogenic ability and the presence of neuronal growth inhibitors in the CNS environment. I review here recent progress in our understanding of neuritogenic inhibitors, with particular emphasis on those with a role in the inhibition of neuronal regeneration in the CNS, their signaling cascades and signal mediators. Neurotrophines acting through the tropomyosin-related kinase (Trk) family and p75 receptors promote neuritogenesis, which appears to require sustained activation of the mitogen activated protein (MAP) kinase pathway, and/or the activation of phosphotidylinositol 3-kinase (PI3 kinase). During development, a plethora of guidance factors and their receptors navigate the growing axon. However, much remained to be learned about the signaling receptors and pathways that mediate the activity of inhibitors of CNS regeneration. There is growing evidence that neuronal guidance molecules, particularly semaphorins, may also have a role as inhibitors of CNS regeneration. Although direct links have not yet been established in many cases, signals from these agents may ultimately converge upon the modulators and effectors of the Rho-family GTPases. Rho-family GTPases and their effectors modulate the activities of actin modifying molecules such as cofilin and profilin, resulting in cytoskeletal changes associated with growth cone extension or retraction.
Collapse
Affiliation(s)
- Bor Luen Tang
- NCA Laboratory, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Singapore.
| |
Collapse
|
25
|
Ellezam B, Bertrand J, Dergham P, McKerracher L. Vaccination stimulates retinal ganglion cell regeneration in the adult optic nerve. Neurobiol Dis 2003; 12:1-10. [PMID: 12609484 DOI: 10.1016/s0969-9961(02)00013-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We examined whether vaccination of adult rats with spinal cord homogenate (SCH) can promote regeneration of retinal ganglion cells (RGCs) after microcrush lesion of the optic nerve. Injured animals vaccinated with SCH showed axon growth into the optic nerve and such regeneration was not observed in animals vaccinated with liver homogenate (LH). Regeneration was not a consequence of neuroprotection since our vaccine did not protect RGCs from axotomy-induced cell death. Sera of vaccinated animals were tested for antibodies against myelin-associated glycoprotein, NogoA, Nogo-66 receptor, or chondroitin sulphate proteoglycans (CSPG), but no significant levels were detected. Antibodies to myelin basic protein were present in the serum of some SCH-vaccinated animals. In culture, serum from SCH-vaccinated animals promoted RGC growth on myelin but not on CSPG. Our results show that the effect of the pro-regenerative vaccine is mediated by antibodies to SCH. However, we were not able to detect a significant immune reaction to growth inhibitory proteins, suggesting alternative mechanisms for the success of vaccination to promote regeneration.
Collapse
Affiliation(s)
- Benjamin Ellezam
- Département de pathologie et biologie cellulaire, Université de Montréal, H3C 3J7, Montréal, Québec, Canada
| | | | | | | |
Collapse
|
26
|
Oertle T, Huber C, van der Putten H, Schwab ME. Genomic structure and functional characterisation of the promoters of human and mouse nogo/rtn4. J Mol Biol 2003; 325:299-323. [PMID: 12488097 DOI: 10.1016/s0022-2836(02)01179-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The reticulon-family member Nogo-A is a potent neurite growth inhibitory protein in vitro and may play a role in the restriction of axonal regeneration after injury and of structural plasticity in the CNS of higher vertebrates. Of the three major isoforms of Nogo, Nogo-A is mostly expressed in the brain, Nogo-B is found in a ubiquitous pattern, and Nogo-C is most highly expressed in muscle. Seven additional splice-variants derived both from differential splicing and differential promoter usage have been identified. Analysis of the TATA-less Nogo-A/B promoter (P1) shows that conserved GC-boxes and a CCAAT-box within the first 500bp upstream of the transcription start are responsible for its regulation. No major differences in the methylation status of the P1 CpG-island in tissues expressing or not expressing Nogo-A/B could be detected, suggesting that silencer elements are involved in the regulation. The specific expression pattern of Nogo-A/B is due to differential splicing. The basal Nogo-C promoter (P2) is regulated by a proximal and a distal element. The 5'UTR of Nogo-C harbours a negative control element. These data may help to identify factors that can modulate Nogo transcription, thus offering an alternative approach for Nogo neutralisation.
Collapse
Affiliation(s)
- Thomas Oertle
- Brain Research Institute, University of Zurich and Department of Biology, Swiss Federal Institute of Technology, Switzerland.
| | | | | | | |
Collapse
|
27
|
Abstract
Axotomized retinal ganglion cells (RGCs) in adult cats offer a good experimental model to understand mechanisms of RGC deteriorations in ophthalmic diseases such as glaucoma and optic neuritis. Alpha ganglion cells in the cat retina have higher ability to survive axotomy and regenerate their axons than beta and non-alpha or beta (NAB) ganglion cells. By contrast, beta cells suffer from rapid cell death by apoptosis between 3 and 7 days after axotomy. We introduced several methods to rescue the axotomized cat RGCs from apoptosis and regenerate their axons; transplantation of the peripheral nerve (PN), intraocular injections of neurotrophic factors, or an antiapoptotic drug. Apoptosis of beta cells can be prevented with intravitreal injections of BDNF+CNTF+forskolin or a caspase inhibitor. The injection of BDNF+CNTF+forskolin also increases the numbers of regenerated beta and NAB cells, but only slightly enhances axonal regeneration of alpha cells. Electrical stimulation to the cut end of optic nerve is effective for the survival of axotomized RGCs in cats as well as in rats. To recover function of impaired vision in cats, further studies should be directed to achieve the following goals: (1). substantial number of regenerating RGCs, (2). reconstruction of the retino-geniculo-cortical pathway, and (3). reconstruction of retinotopy in the target visual centers.
Collapse
Affiliation(s)
- Masami Watanabe
- Department of Physiology, Institute for Developmental Research, Kasugai, Aichi 480-0392, Japan.
| | | |
Collapse
|
28
|
Dallimore EJ, Cui Q, Beazley LD, Harvey AR. Postnatal innervation of the rat superior colliculus by axons of late-born retinal ganglion cells. Eur J Neurosci 2002; 16:1295-304. [PMID: 12405990 DOI: 10.1046/j.1460-9568.2002.02178.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rat retinal ganglion cells (RGCs) are generated between embryonic day (E) 13 and E19. Retinal axons first reach the superior colliculus at E16/16.5 but the time of arrival of axons from late-born RGCs is unknown. This study examined (i) whether there is a correlation between RGC genesis and the timing of retinotectal innervation and (ii) when axons of late-born RGCs reach the superior colliculus. Pregnant Wistar rats were injected intraperitoneally with bromodeoxyuridine (BrdU) on E16, E18 or E19. Pups from these litters received unilateral superior colliculus injections of fluorogold (FG) at ages between postnatal (P) day P0 and P6, and were perfused 1-2 days later. RGCs in 3 rats from each BrdU litter were labelled in adulthood by placing FG onto transected optic nerve. Retinas were cryosectioned and the number of FG, BrdU and double-labelled (FG+/BrdU+) RGCs quantified. In the E16 group, the proportion of FG-labelled RGCs that were BrdU+ did not vary with age, indicating that axons from these cells had reached the superior colliculus by P0/P1. In contrast, for the smaller cohorts of RGCs born on E18 or E19, the proportion of BrdU+ cells that were FG+ increased significantly after birth; axons from most RGCs born on E19 were not retrogradely FG-labelled until P4/P5. Thus there is a correlation between birthdate and innervation in rat retinotectal pathways. Furthermore, compared to the earliest born RGCs, axons from late-born RGCs take about three times longer to reach the superior colliculus. Later-arriving axons presumably encounter comparatively different growth terrains en route and eventually innervate more differentiated target structures.
Collapse
Affiliation(s)
- Elizabeth J Dallimore
- School of Anatomy and Human Biology, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, WA 6009, Australia
| | | | | | | |
Collapse
|
29
|
Lang DM, del Mar Romero-Aleman M, Arbelo-Galvan JF, Stuermer CAO, Monzon-Mayor M. Regeneration of retinal axons in the lizard Gallotia galloti is not linked to generation of new retinal ganglion cells. JOURNAL OF NEUROBIOLOGY 2002; 52:322-35. [PMID: 12210099 DOI: 10.1002/neu.10099] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Using anterograde tracing with HRP and antibodies (ABs) against neurofilaments, we show that regrowth of retinal ganglion cell (RGC) axons in the lizard Gallotia galloti commences only 2 months after optic nerve transection (ONS) and continues over at least 9 months. This is unusually long when compared to RGC axon regeneration in fish or amphibians. Following ONS, lizard RGCs up-regulate the immediate early gene C-JUN for 9 months or longer, indicating their reactive state. In keeping with the in vivo data, axon outgrowth from lizard retinal explants is increased above control levels from 6 weeks, reaches its maximum as late as 3 months, and remains elevated for at least 1 year after ONS. By means of BrdU incorporation assays and antiproliferating cell nuclear antigen immunohistochemistry, we show that the late axon outgrowth is not derived from new RGCs that might have arisen in reaction to ONS: no labeled cells were detected in lizard retinas at 0.5, 1, 1.5, 3, 6, and 12 months after ONS. Conversely, numbers of RGCs undergoing apoptosis were too low to be detectable in TUNEL assays at any time after ONS. These results demonstrate that retinal axon regeneration in G. galloti is due to axon regrowth from the resident population of RGCs, which remain in a reactive state over an extended time interval. Neurogenesis does not appear to be involved in RGC axon regrowth in G. galloti.
Collapse
Affiliation(s)
- Dirk M Lang
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Observatory 7925, South Africa.
| | | | | | | | | |
Collapse
|
30
|
Goldberg JL, Klassen MP, Hua Y, Barres BA. Amacrine-signaled loss of intrinsic axon growth ability by retinal ganglion cells. Science 2002; 296:1860-4. [PMID: 12052959 DOI: 10.1126/science.1068428] [Citation(s) in RCA: 350] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The central nervous system (CNS) loses the ability to regenerate early during development, but it is not known why. The retina has long served as a simple model system for study of CNS regeneration. Here we show that amacrine cells signal neonatal rat retinal ganglion cells (RGCs) to undergo a profound and apparently irreversible loss of intrinsic axon growth ability. Concurrently, retinal maturation triggers RGCs to greatly increase their dendritic growth ability. These results suggest that adult CNS neurons fail to regenerate not only because of CNS glial inhibition but also because of a loss of intrinsic axon growth ability.
Collapse
Affiliation(s)
- Jeffrey L Goldberg
- Stanford University School of Medicine, Department of Neurobiology, Sherman Fairchild Science Building D231, 299 Campus Drive, Stanford, CA 94305-5125, USA.
| | | | | | | |
Collapse
|
31
|
Skaper SD, Moore SE, Walsh FS. Cell signalling cascades regulating neuronal growth-promoting and inhibitory cues. Prog Neurobiol 2001; 65:593-608. [PMID: 11728645 DOI: 10.1016/s0301-0082(01)00017-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
During development of the nervous system, neurons extend axons over considerable distances in a highly stereospecific fashion in order to innervate their targets in an appropriate manner. This involves the recognition, by the axonal growth cone, of guidance cues that determine the pathway taken by the axons. These guidance cues can act to promote and/or repel growth cone advance, and they can act either locally or at a distance from their place of synthesis. The directed growth of axons is partly governed by cell adhesion molecules (CAMs) on the neuronal growth cone that bind to CAMs on the surface of other axons or non-neuronal cells. In vitro assays have established the importance of the CAMs (N-CAM, N-cadherin and the L1 glycoprotein) in promoting axonal growth over cells, such as Schwann cells, astrocytes and muscle cells. Strong evidence now exists implicating the fibroblast growth factor receptor tyrosine kinase as the primary signal transduction molecule in the CAM pathway. Cell adhesion molecules are important constituents of synapses, and CAMs appear to play important and diverse roles in regulating synaptic plasticity associated with learning and memory. Negative extracellular signals which physically direct neurite growth have also been described. The latter include the neuronal growth inhibitory proteins Nogo and myelin-associated glycoprotein, as well as the growth cone collapsing Semaphorins/neuropilins. Although less well characterised, evidence is now beginning to emerge describing a role for Rho kinase-mediated signalling in inhibition of neurite outgrowth. This review focuses on some of the major themes and ideas associated with this fast-moving field of neuroscience.
Collapse
Affiliation(s)
- S D Skaper
- Neurology Centre of Excellence for Drug Discovery, GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Essex CM19 5AW, Harlow, UK
| | | | | |
Collapse
|
32
|
Allen GW, Liu J, Kirby MA, De León M. Induction and axonal localization of epithelial/epidermal fatty acid-binding protein in retinal ganglion cells are associated with axon development and regeneration. J Neurosci Res 2001; 66:396-405. [PMID: 11746357 DOI: 10.1002/jnr.1232] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Epithelial/epidermal fatty acid-binding protein (E-FABP) is induced in peripheral neurons during nerve regeneration and is found at high levels in central neurons during neuronal migration and development. Furthermore, E-FABP expression is required for normal neurite outgrowth in PC12 cells treated with nerve growth factor (NGF). The present study examined whether E-FABP plays a role in retinal ganglion cell (RGC) differentiation and axon growth. Rat retinal tissues from embryonic (E) and postnatal (P) development through adulthood were examined using immunocytochemical labeling with E-FABP and growth-associated protein 43 (GAP-43) antibodies. E-FABP colocalized with GAP-43 at E14 through P10. At E14, E-FABP immunoreactivity was confined to the somas of GAP-43-positive cells in the ganglion cell layer, but it was localized to their axons by E15. The axons in the optic nerve were GAP-43-positive and E-FABP-negative on E15, but the two proteins were colocalized by E18. Retinal cultures at E15 confirmed that E-FABP and GAP-43 colocalize in RGCs. Postnatally, labeling was present between P1 and P10 but decreased at older ages and was minimally present or absent in adult animals. Western immunoblotting revealed that at E18, P1, and P10 E-FABP levels were at least fourfold greater than those in the adult. By P15, protein levels were only twofold greater, with adult levels reached by P31. Furthermore, E-FABP could be reinduced during axon regeneration. Dissociated P15 retinal cells cultured in the presence of brain-derived neurotrophic factor, ciliary neurotrophic factor, and basic fibroblast growth factor exhibited sixfold more GAP-43 and E-FABP double-positive RGCs (cell body and axons) than controls. Moreover, all GAP-43-immunoreactive RGCs were also positive for E-FABP. Taken together, these results indicate the following: 1) E-FABP is expressed in RGCs as they reached the ganglion cell layer and 2) E-FABP plays a functional role in the elaboration of RGC axons in both development and regeneration.
Collapse
Affiliation(s)
- G W Allen
- Department of Physiology and Pharmacology, Center for Molecular Biology and Gene Therapy, Loma Linda University, Loma Linda, California 92350, USA
| | | | | | | |
Collapse
|
33
|
Abstract
Following injury, axons of the adult mammalian central nervous system (CNS) fail to regenerate. As a result, CNS trauma generally results in severe and persistent functional deficits. The inability of CNS axons to regenerate is largely associated with nonneuronal aspects of the CNS environment that are inhibitory to axonal elongation. This inhibition is mediated by the glial scar, including reactive astrocytes, and by the myelin-associated neurite outgrowth inhibitors chondroitin sulfate proteoglycans, myelin-associated glycoprotein, and Nogo. Nogo is an integral membrane protein that localizes to CNS, but not peripheral nervous system, myelin. In vitro characterization of Nogo has demonstrated its function as a potent inhibitor of axon elongation. In vivo neutralization of Nogo activity results in enhanced axonal regeneration and functional recovery following CNS injury as well as increased plasticity in uninjured CNS fibers. These findings suggest that Nogo may be a major contributor to the nonpermissive nature of the CNS environment.
Collapse
Affiliation(s)
- T Grandpré
- Department of Neurology, Yale University School of Medicine New Haven, Connecticut 06520, USA
| | | |
Collapse
|
34
|
Abstract
In a variety of adult CNS injury models, embryonic neurons exhibit superior regenerative performance when compared with adult neurons. It is unknown how young neurons extend axons in the injured adult brain, in which adult neurons fail to regenerate. This study shows that cultured adult neurons do not adapt to conditions that are characteristic of the injured adult CNS: low levels of growth-promoting molecules and the presence of inhibitory proteoglycans. In contrast, young neurons readily adapt to these same conditions, and adaptation is accompanied by an increase in the expression of receptors for growth-promoting molecules (receptors of the integrin family). Surprisingly, the regenerative performance of adult neurons can be restored to that of young neurons by gene transfer-mediated expression of a single alpha-integrin.
Collapse
|
35
|
Oudega M, Rosano C, Sadi D, Wood PM, Schwab ME, Hagg T. Neutralizing antibodies against neurite growth inhibitor NI-35/250 do not promote regeneration of sensory axons in the adult rat spinal cord. Neuroscience 2001; 100:873-83. [PMID: 11036221 DOI: 10.1016/s0306-4522(00)00350-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neutralization of the myelin-associated neurite growth inhibitors NI-35 and NI-250 by IN-1 antibodies can promote axonal regeneration of several types of central nervous neurons. Here, we investigated in adult rats whether IN-1 can promote regeneration of ascending sensory axons across a peripheral nerve bridge back into the spinal cord. IN-1 was administered by hybridoma cells injected in the cerebral cortex or thoracic cord, its presence confirmed in tissue sections and cerebrospinal fluid, and its effectiveness demonstrated in co-cultures of oligodendrocytes and sensory neurons. With a two week infusion of control vehicle into the dorsal spinal cord 3 mm rostral to the nerve graft, only 3+/-2% of the anterogradely labeled sensory fibers present at the rostral end of the nerve graft had grown up to 0.5 mm, but not farther into the spinal cord. A similar limited extent of regeneration was seen with IN-1 or with infusion of Dantrolene, an inhibitor of NI-35/250 activity in vitro. With infusion of nerve growth factor rostral to the nerve graft, 40% of the fibers at the rostral end of the graft were found at 0.5 mm, 34% at 1 mm, 24% at 2 mm and 14% at 3 mm (the infusion site) into the spinal cord. Treatment with IN-l antibodies did not enhance the growth-promoting effects of nerve growth factor. We suggest that the neurite growth inhibitors NI-35 or NI-250 do not play a major inhibitory role in the regeneration of the ascending sensory fibers across a nerve bridge and back into the spinal cord of the adult rat.
Collapse
Affiliation(s)
- M Oudega
- The Miami Project to Cure Paralysis, University of Miami School of Medicine, Miami, FL 33136, USA.
| | | | | | | | | | | |
Collapse
|
36
|
Ferguson TA, Muir D. MMP-2 and MMP-9 increase the neurite-promoting potential of schwann cell basal laminae and are upregulated in degenerated nerve. Mol Cell Neurosci 2000; 16:157-67. [PMID: 10924258 DOI: 10.1006/mcne.2000.0859] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Compared to degenerated nerves, the ability of normal adult peripheral nerve to support axonal regeneration is poor and may be attributed to the inhibition of endoneurial laminin by chondroitin sulfate proteoglycan (CSPG). In cryoculture assays, neuritic growth of neonatal and adult peripheral neurons was increased on sections of normal nerve by pretreatment with CSPG-degrading enzymes, including the matrix metalloproteinases MMP-2 and MMP-9. Axonal regeneration is known to occur within the Schwann cell basal laminae of degenerated nerve. Similarly, deconvolution microscopy revealed that neuritic growth on nerve tissue sections occurred principally on the lumenal surface of enzymatically modified basal laminae. Compared to normal nerve, there was a marked increase in the neurite-promoting activity of the degenerated nerve, and this activity was not increased significantly by subsequent MMP treatment. Additionally, the expression and activation of MMP-2 and MMP-9 were elevated in degenerated nerve, suggesting that degradation of inhibitory CSPG by the MMPs contributes to the growth-promoting properties of degenerated nerve.
Collapse
Affiliation(s)
- T A Ferguson
- Division of Neurology, University of Florida Brain Institute and College of Medicine, Gainsville, Florida 32610-0296, USA
| | | |
Collapse
|
37
|
Abstract
The lack of regrowth of injured neurons in the adult central nervous system (CNS) of higher vertebrates was accepted as a fact for many decades. In the last few years a very different view emerged; regeneration of lesioned fibre tracts in vivo could be induced experimentally, and molecules that are responsible for inhibition and repulsion of growing neurites have been defined. Mechanisms that link cellular phenomena like growth cone turning or growth cone collapse to intracellular changes in second messenger systems and cytoskeletal dynamics became unveiled. This article reviews recent developments in this field, focusing especially on one of the best characterised neurite out-growth inhibitory molecules found in CNS myelin that was recently cloned: Nogo-A. Nogo-A is a high molecular weight transmembrane protein and an antigen of the monoclonal antibody mAb IN-1 that was shown to promote long-distance regeneration and functional recovery in vivo when applied to spinal cord-injured adult rats. Nogo-A is expressed by oligodendrocytes in white matter of the CNS. With the molecular characterisation of this factor new possibilities open up to achieve structural and functional repair of the injured CNS.
Collapse
Affiliation(s)
- A B Huber
- Brain Research Institute, Department of Neuromorphology, University of Zurich and Swiss Federal Institute of Technology Zurich, Switzerland
| | | |
Collapse
|
38
|
Fritz JL, VanBerkum MF. Calmodulin and son of sevenless dependent signaling pathways regulate midline crossing of axons in the Drosophila CNS. Development 2000; 127:1991-2000. [PMID: 10751187 DOI: 10.1242/dev.127.9.1991] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The establishment of axon trajectories is ultimately determined by the integration of intracellular signaling pathways. Here, a genetic approach in Drosophila has demonstrated that both Calmodulin and Son of sevenless signaling pathways are used to regulate which axons cross the midline. A loss in either signaling pathway leads to abnormal projection of axons across the midline and these increase with roundabout or slit mutations. When both Calmodulin and Son of sevenless are disrupted, the midline crossing of axons mimics that seen in roundabout mutants, although Roundabout remains expressed on crossing axons. Calmodulin and Son of sevenless also regulate axon crossing in a commissureless mutant. These data suggest that Calmodulin and Son of sevenless signaling pathways function to interpret midline repulsive cues which prevent axons crossing the midline.
Collapse
Affiliation(s)
- J L Fritz
- Department of Biological Sciences, Wayne State University, Detroit, MI 48202, USA
| | | |
Collapse
|
39
|
GrandPré T, Nakamura F, Vartanian T, Strittmatter SM. Identification of the Nogo inhibitor of axon regeneration as a Reticulon protein. Nature 2000; 403:439-44. [PMID: 10667797 DOI: 10.1038/35000226] [Citation(s) in RCA: 866] [Impact Index Per Article: 36.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Adult mammalian axon regeneration is generally successful in the peripheral nervous system (PNS) but is dismally poor in the central nervous system (CNS). However, many classes of CNS axons can extend for long distances in peripheral nerve grafts. A comparison of myelin from the CNS and the PNS has revealed that CNS white matter is selectively inhibitory for axonal outgrowth. Several components of CNS white matter, NI35, NI250(Nogo) and MAG, that have inhibitory activity for axon extension have been described. The IN-1 antibody, which recognizes NI35 and NI250(Nogo), allows moderate degrees of axonal regeneration and functional recovery after spinal cord injury. Here we identify Nogo as a member of the Reticulon family, Reticulon 4-A. Nogo is expressed by oligodendrocytes but not by Schwann cells, and associates primarily with the endoplasmic reticulum. A 66-residue lumenal/extracellular domain inhibits axonal extension and collapses dorsal root ganglion growth cones. In contrast to Nogo, Reticulon 1 and 3 are not expressed by oligodendrocytes, and the 66-residue lumenal/extracellular domains from Reticulon 1, 2 and 3 do not inhibit axonal regeneration. These data provide a molecular basis to assess the contribution of Nogo to the failure of axonal regeneration in the adult CNS.
Collapse
Affiliation(s)
- T GrandPré
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, USA
| | | | | | | |
Collapse
|
40
|
Bandtlow CE, Schwab ME. NI-35/250/nogo-a: a neurite growth inhibitor restricting structural plasticity and regeneration of nerve fibers in the adult vertebrate CNS. Glia 2000; 29:175-81. [PMID: 10625336 DOI: 10.1002/(sici)1098-1136(20000115)29:2<175::aid-glia11>3.0.co;2-f] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- C E Bandtlow
- Institut für Hirnforschung, University of Zurich, Zurich, Switzerland.
| | | |
Collapse
|
41
|
Ng WP, Lozano AM. Neuronal age influences the response to neurite outgrowth inhibitory activity in the central and peripheral nervous systems. Brain Res 1999; 836:49-61. [PMID: 10415404 DOI: 10.1016/s0006-8993(99)01588-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Axonal regeneration is abortive in the central nervous system (CNS) of adult mammals, but readily occurs in the injured peripheral nervous system (PNS). Recent experiments indicate an important role for both intrinsic neuronal features and extrinsic substrate properties in determining the propensity for axonal regrowth. In particular, certain components of adult mammalian CNS myelin have been shown to exert a strong inhibitory influence on neurite outgrowth. To determine whether the potent neurite outgrowth inhibitory activity found in CNS myelin may also be present in PNS myelin and to study the influence of neuronal age on neurite outgrowth, we used a cryoculture assay in which dissociated rat dorsal root ganglion (DRG) neurons of different ages were challenged to extend neurites on fractionated myelin and cryostat sections from the PNS (sciatic nerve and myelin-free degenerated sciatic nerve) and CNS (optic nerve) of adult rats. The CNS environment of the optic nerve did not support E17 to P8 DRG neurite adhesion or outgrowth. E17 DRG neurons, unlike their older counterparts, however, were able to attach and extend neurites onto normal sciatic nerve and onto purified PNS myelin. In contrast, a vigorous neurite outgrowth response from all the ages tested was observed on the myelin-free degenerated sciatic nerve. These results indicate that PNS myelin is a potent inhibitor of neurite outgrowth and that DRG neuronal age plays an important role in determining the propensity for neurite outgrowth and regenerative response on inhibitory PNS and CNS substrata.
Collapse
Affiliation(s)
- W P Ng
- Division of Neurosurgery and Playfair Neuroscience Unit, The Toronto Hospital, 399 Bathurst Street, Toronto, ON, Canada
| | | |
Collapse
|
42
|
Abstract
Membrane proteins on oligodendrocytes and CNS myelin (NI35/250) have been shown to block axon out-growth in culture, and this is thought to be one of the major reasons for severely limited regeneration of severed axons in the CNS of higher vertebrates. In a recent study, adult dorsal root ganglion (DRG) neurons, which are sensitive to these inhibitory proteins, regenerated successfully after transplantation into two white matter tracts of the rat brain without any intervention to suppress the inhibitory activity of CNS myelin. The results and implications of these two studies are considered.
Collapse
Affiliation(s)
- R Douglas Fields
- Laboratory of Developmental Neurobiology, NICHD, National Institutes of Health, Bethesda, Maryland
| | - Martin E Schwab
- Brain Research Institute, University of Zurich, Swiss Federal Institute of Technology, Zurich, Switzerland
| | - Jerry Silver
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio
| |
Collapse
|
43
|
Zuo J, Neubauer D, Dyess K, Ferguson TA, Muir D. Degradation of chondroitin sulfate proteoglycan enhances the neurite-promoting potential of spinal cord tissue. Exp Neurol 1998; 154:654-62. [PMID: 9878200 DOI: 10.1006/exnr.1998.6951] [Citation(s) in RCA: 235] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The contribution of chondroitin sulfate proteoglycan (CSPG) in the suppression of axonal growth in rat spinal cord has been examined by means of an in vitro bioassay in which regenerating neurons are grown on tissue section substrata. Dissociated embryonic chick dorsal root ganglionic neurons were grown on normal and injured adult spinal cord tissue sections treated with chondroitinases. Neuritic growth on normal spinal cord tissue was meager. However, both the percentage of neurons with neurites and the average neurite length were substantially greater on sections treated with chondroitinase ABC. Enzymes that specifically degraded dermatan sulfate or hyaluronan were ineffective. Neuritic growth was significantly greater on injured (compared to normal) spinal cord and a further dramatic increase resulted from chondroitinase ABC treatment. Neurites grew equally within white and gray matter regions after chondroitinase treatment. Observed increases in neurite outgrowth on chondroitinase-treated tissues were largely inhibited in the presence of function-blocking laminin antibodies. These findings indicate that inhibitory CSPG is widely distributed and predominant in both normal and injured spinal cord tissues. Additionally, inhibitory CSPG is implicated in negating the potential stimulatory effects of laminin that might otherwise support spinal cord regeneration.
Collapse
Affiliation(s)
- J Zuo
- Department of Pediatrics, University of Florida Brain Institute and College of Medicine, Gainesville, Florida, 32610-0296, USA
| | | | | | | | | |
Collapse
|