351
|
Li H, Wu W. Microtubule stabilization promoted axonal regeneration and functional recovery after spinal root avulsion. Eur J Neurosci 2017; 46:1650-1662. [PMID: 28444817 DOI: 10.1111/ejn.13585] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 04/09/2017] [Accepted: 04/09/2017] [Indexed: 12/20/2022]
Abstract
A spinal root avulsion injury disconnects spinal roots with the spinal cord. The rampant motoneuron death, inhibitory CNS/PNS transitional zone (TZ) for axonal regrowth and limited regeneration speed together lead to motor dysfunction. Microtubules rearrange to assemble a new growth cone and disorganized microtubules underline regeneration failure. It has been shown that microtubule-stabilizing drug, Epothilone B, enhanced axonal regeneration and attenuated fibrotic scaring after spinal cord injury. Here, we are reporting that after spinal root avulsion+ re-implantation in adult rats, EpoB treatment improved motor functional recovery and potentiated electrical responses of motor units. It facilitated axons to cross the TZ and promoted more and bigger axons in the peripheral nerve. Neuromuscular junctions were reformed with better preserved postsynaptic structure, and muscle atrophy was prevented by EpoB administration. Our study showed that EpoB was a promising therapy for promoting axonal regeneration after peripheral nerve injury.
Collapse
Affiliation(s)
- Heng Li
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, the University of Hong Kong, L1-39, 21 Sassoon Road, Pokfulam, Hong Kong SAR, China
| | - Wutian Wu
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, the University of Hong Kong, L1-39, 21 Sassoon Road, Pokfulam, Hong Kong SAR, China.,State Key Laboratory of Brain and Cognitive Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.,Joint Laboratory of Jinan University and the University of Hong Kong, GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
| |
Collapse
|
352
|
Knowlton WM, Hubert T, Wu Z, Chisholm AD, Jin Y. A Select Subset of Electron Transport Chain Genes Associated with Optic Atrophy Link Mitochondria to Axon Regeneration in Caenorhabditis elegans. Front Neurosci 2017; 11:263. [PMID: 28539870 PMCID: PMC5423972 DOI: 10.3389/fnins.2017.00263] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 04/24/2017] [Indexed: 12/13/2022] Open
Abstract
The role of mitochondria within injured neurons is an area of active interest since these organelles are vital for the production of cellular energy in the form of ATP. Using mechanosensory neurons of the nematode Caenorhabditis elegans to test regeneration after neuronal injury in vivo, we surveyed genes related to mitochondrial function for effects on axon regrowth after laser axotomy. Genes involved in mitochondrial transport, calcium uptake, mitophagy, or fission and fusion were largely dispensable for axon regrowth, with the exception of eat-3/Opa1. Surprisingly, many genes encoding components of the electron transport chain were dispensable for regrowth, except for the iron-sulfur proteins gas-1, nduf-2.2, nduf-7, and isp-1, and the putative oxidoreductase rad-8. In these mutants, axonal development was essentially normal and axons responded normally to injury by forming regenerative growth cones, but were impaired in subsequent axon extension. Overexpression of nduf-2.2 or isp-1 was sufficient to enhance regrowth, suggesting that mitochondrial function is rate-limiting in axon regeneration. Moreover, loss of function in isp-1 reduced the enhanced regeneration caused by either a gain-of-function mutation in the calcium channel EGL-19 or overexpression of the MAP kinase DLK-1. While the cellular function of RAD-8 remains unclear, our genetic analyses place rad-8 in the same pathway as other electron transport genes in axon regeneration. Unexpectedly, rad-8 regrowth defects were suppressed by altered function in the ubiquinone biosynthesis gene clk-1. Furthermore, we found that inhibition of the mitochondrial unfolded protein response via deletion of atfs-1 suppressed the defective regrowth in nduf-2.2 mutants. Together, our data indicate that while axon regeneration is not significantly affected by general dysfunction of cellular respiration, it is sensitive to the proper functioning of a select subset of electron transport chain genes, or to the cellular adaptations used by neurons under conditions of injury.
Collapse
Affiliation(s)
- Wendy M Knowlton
- Section of Neurobiology, Division of Biological Sciences, University of CaliforniaSan Diego, CA, USA
| | - Thomas Hubert
- Section of Neurobiology, Division of Biological Sciences, University of CaliforniaSan Diego, CA, USA
| | - Zilu Wu
- Howard Hughes Medical Institute, University of CaliforniaSan Diego, CA, USA
| | - Andrew D Chisholm
- Section of Neurobiology, Division of Biological Sciences, University of CaliforniaSan Diego, CA, USA
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, University of CaliforniaSan Diego, CA, USA.,Howard Hughes Medical Institute, University of CaliforniaSan Diego, CA, USA.,Department of Cellular and Molecular Medicine, School of Medicine, University of CaliforniaSan Diego, CA, USA
| |
Collapse
|
353
|
Niu J. Neurodegeneration and regeneration. J Neurosci Res 2017; 95:1525-1527. [PMID: 28485030 DOI: 10.1002/jnr.24069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 03/28/2017] [Accepted: 03/31/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Jingwen Niu
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair).,Lewis Katz School of Medicine, Temple University, 3500 N. Broad Street, Philadelphia, PA, 19140
| |
Collapse
|
354
|
Kajstura TJ, Dougherty SE, Linden DJ. Serotonin axons in the neocortex of the adult female mouse regrow after traumatic brain injury. J Neurosci Res 2017; 96:512-526. [PMID: 28485037 DOI: 10.1002/jnr.24059] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 02/16/2017] [Accepted: 03/08/2017] [Indexed: 01/01/2023]
Abstract
It is widely held that injured neurons in the central nervous system do not undergo axonal regrowth. However, there is mounting evidence that serotonin axons are a notable exception. Serotonin axons undergo long-distance regrowth in the neocortex after amphetamine lesion, and, following a penetrating stab injury, they can regrow from cut ends to traverse the stab rift. Traumatic brain injury (TBI) is clinically prevalent and can lead to pathologies, such as depression, that are related to serotonergic dysfunction. Thus, whether serotonin axons can regrow after TBI is an important question. We used two models for TBI-a persistent open skull condition and controlled cortical impact-to evoke injury in adult female mouse neocortex, and assessed serotonin axon density 1 week, 1 month, and 3 months after injury by serotonin transporter immunohistochemistry. We found that after both forms of TBI, serotonin axon density is decreased posterior but not anterior to the injury site when measured in layer 1 at 1 week post surgery, and that serotonin axons are capable of regrowing into the distal zone to increase density by 1 month post surgery. This pattern is consistent with the anterior-to-posterior course of serotonin axons in the neocortex. TBI in these models is associated with significant reactive astrogliosis both anterior and posterior to the impact, but the degree of reactive astrogliosis is not correlated with serotonin axon density when measured 1 week after TBI. Microglial density remains constant following both types of injuries, but microglial condensation was detected 1 week after controlled cortical impact.
Collapse
Affiliation(s)
- Tymoteusz J Kajstura
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sarah E Dougherty
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - David J Linden
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland
| |
Collapse
|
355
|
Cell transplantation therapy for spinal cord injury. Nat Neurosci 2017; 20:637-647. [DOI: 10.1038/nn.4541] [Citation(s) in RCA: 435] [Impact Index Per Article: 62.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 02/22/2017] [Indexed: 02/07/2023]
|
356
|
Lv D, Zhou L, Zheng X, Hu Y. Sustained release of collagen VI potentiates sciatic nerve regeneration by modulating macrophage phenotype. Eur J Neurosci 2017; 45:1258-1267. [PMID: 28263445 DOI: 10.1111/ejn.13558] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 01/18/2017] [Accepted: 02/07/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Dan Lv
- The graduate School; Tianjin Medical University; Tianjin China
- Department of Orthopaedics; Pingjin Hospital; Logistics University of the Chinese People's Armed Police Forces; Tianjin China
| | - Lijuan Zhou
- Key Laboratory of Oral Diseases Research of Anhui Province (Anhui); Stomatologic Hospital & College; Anhui Medical University; Hefei China
| | - Xianyu Zheng
- Key Laboratory of Oral Diseases Research of Anhui Province (Anhui); Stomatologic Hospital & College; Anhui Medical University; Hefei China
| | - Yongcheng Hu
- Department of Orthopaedic Oncology; Tianjin Hospital; Tianjin 300210 China
| |
Collapse
|
357
|
Weng YL, An R, Cassin J, Joseph J, Mi R, Wang C, Zhong C, Jin SG, Pfeifer GP, Bellacosa A, Dong X, Hoke A, He Z, Song H, Ming GL. An Intrinsic Epigenetic Barrier for Functional Axon Regeneration. Neuron 2017; 94:337-346.e6. [PMID: 28426967 PMCID: PMC6007997 DOI: 10.1016/j.neuron.2017.03.034] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 02/05/2017] [Accepted: 03/23/2017] [Indexed: 12/15/2022]
Abstract
Mature neurons in the adult peripheral nervous system can effectively switch from a dormant state with little axonal growth to robust axon regeneration upon injury. The mechanisms by which injury unlocks mature neurons' intrinsic axonal growth competence are not well understood. Here, we show that peripheral sciatic nerve lesion in adult mice leads to elevated levels of Tet3 and 5-hydroxylmethylcytosine in dorsal root ganglion (DRG) neurons. Functionally, Tet3 is required for robust axon regeneration of DRG neurons and behavioral recovery. Mechanistically, peripheral nerve injury induces DNA demethylation and upregulation of multiple regeneration-associated genes in a Tet3- and thymine DNA glycosylase-dependent fashion in DRG neurons. In addition, Pten deletion-induced axon regeneration of retinal ganglion neurons in the adult CNS is attenuated upon Tet1 knockdown. Together, our study suggests an epigenetic barrier that can be removed by active DNA demethylation to permit axon regeneration in the adult mammalian nervous system.
Collapse
Affiliation(s)
- Yi-Lan Weng
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ran An
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Huashan Hospital, State Key Laboratory of Medical Neurobiology, Fudan University, Shanghai 200040, China
| | - Jessica Cassin
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Pre-doctoral Human Genetics Training Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jessica Joseph
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ruifa Mi
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Chen Wang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Chun Zhong
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Seung-Gi Jin
- Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Gerd P. Pfeifer
- Center for Epigenetics, Van Andel Research Institute, Grand Rapids, MI 49503, USA
| | - Alfonso Bellacosa
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
| | - Xinzhong Dong
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Ahmet Hoke
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, and Department of Neurology, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Hongjun Song
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Pre-doctoral Human Genetics Training Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neuroscience, Mahoney Institute for Neurosciences, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Guo-li Ming
- Institute for Cell Engineering, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
- Department of Neuroscience, Mahoney Institute for Neurosciences, Perelman School for Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| |
Collapse
|
358
|
Levin LA, Miller JW, Zack DJ, Friedlander M, Smith LEH. Special Commentary: Early Clinical Development of Cell Replacement Therapy: Considerations for the National Eye Institute Audacious Goals Initiative. Ophthalmology 2017; 124:926-934. [PMID: 28365209 DOI: 10.1016/j.ophtha.2017.02.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/09/2017] [Accepted: 02/14/2017] [Indexed: 11/17/2022] Open
Abstract
The National Eye Institute launched the Audacious Goals Initiative (AGI) in 2013 with the aim "to restore vision through the regeneration of neurons and neural connections in the eye and visual system." An AGI Town Hall held at the Association for Research in Vision and Ophthalmology Annual Meeting in 2016 brought together basic, translational, and clinical scientists to address the clinical implications of the AGI, with a particular emphasis on diseases amenable to regenerative medicine and strategies to deal with barriers to progess. An example of such a barrier is that replacement of lost neurons may be insufficient because damage to other neurons and non-neuronal cells is common in retinal and optic nerve disease. Reparative processes such as gliosis and fibrosis also can make it difficult to replenish and regenerate neurons. Other issues include choice of animal models, selecting appropriate endpoints, ethics of informed consent, and regulatory issues. Another area critical to next steps in the AGI is the choice of target diseases and the stage at which early development studies should be focused. For example, an advantage of doing clinical trials in patients with early disease is that supporting cellular and structural constituents are still likely to be present. However, regenerative studies in patients with late disease make it easier to detect the effects of replacement therapy against the background of severe visual loss, whereas it may be harder to detect incremental improvement in visual function in those with early disease and considerable remaining visual function. Achieving the goals of the AGI also requires preclinical advances, new imaging techniques, and optimizing translational issues. The work of the AGI is expected to take at least 10 years but should eventually result in therapies to restore some degree of vision to the blind.
Collapse
Affiliation(s)
- Leonard A Levin
- Department of Ophthalmology, McGill University, Montreal, Canada; Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin.
| | - Joan W Miller
- Department of Ophthalmology, Harvard Medical School, Massachusetts Eye and Ear, Massachusetts General Hospital, Boston, Massachusetts
| | - Donald J Zack
- Departments of Ophthalmology, Neuroscience, Molecular Biology and Genetics, and Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Martin Friedlander
- Department of Cell and Molecular Biology, The Scripps Research Institute, La Jolla, California; The Lowy Medical Research Institute, La Jolla, California
| | - Lois E H Smith
- Department of Ophthalmology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
359
|
Active Nerve Regeneration with Failed Target Reinnervation Drives Persistent Neuropathic Pain. eNeuro 2017; 4:eN-NWR-0008-17. [PMID: 28197545 PMCID: PMC5290455 DOI: 10.1523/eneuro.0008-17.2017] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Revised: 01/19/2017] [Accepted: 01/23/2017] [Indexed: 12/29/2022] Open
Abstract
Peripheral nerves can regenerate and, when injured, may cause neuropathic pain. We propose that the active regeneration process plays a pivotal role in the maintenance of neuropathic pain. In one commonly used rodent neuropathic pain model, pronounced pain behaviors follow ligation and cutting of the L5 spinal nerve. We found that the injured nerve regenerates into the sciatic nerve and functionally reinnervates target tissues: the regenerated nerve conducts electrical signals, mechanical responses, and tracers between the leg/hindpaw and axotomized sensory ganglion. The regenerating nerve is the primary source of abnormal spontaneous activity detected in vivo. Disrupting the regeneration inhibited pain. First, semaphorin 3A, an inhibitory axonal guidance molecule, reduced functional regeneration, spontaneous activity, and pain behaviors when applied to the injury site in vivo. Second, knockdown of the upregulated growth-associated protein 43 (GAP43) with siRNA injected into the axotomized sensory ganglion reduced pain behaviors. We next examined the spared nerve injury model, in which pain behaviors are essentially permanent. The regeneration resulted in tangled GAP43-positive neuromas at the nerve injury site without target reinnervation. Perfusing the nerve stump with semaphorin 3A, but not removing the tangled fibers, prevented or reversed pain behaviors. This effect far outlasted the semaphorin 3A perfusion. Hence, in this model the long-lasting chronic pain may reflect the anatomical inability of regenerating nerves to successfully reinnervate target tissues, resulting in an ongoing futile regeneration process. We propose that specifically targeting the regeneration process may provide effective long-lasting pain relief in patients when functional reinnervation becomes impossible.
Collapse
|
360
|
Holland SM, Thomas GM. Roles of palmitoylation in axon growth, degeneration and regeneration. J Neurosci Res 2017; 95:1528-1539. [PMID: 28150429 DOI: 10.1002/jnr.24003] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 11/09/2016] [Accepted: 11/28/2016] [Indexed: 12/11/2022]
Abstract
The protein-lipid modification palmitoylation plays important roles in neurons, but most attention has focused on roles of this modification in the regulation of mature pre- and post-synapses. However, exciting recent findings suggest that palmitoylation is also critical for both the growth and integrity of neuronal axons and plays previously unappreciated roles in conveying axonal anterograde and retrograde signals. Here we review these emerging roles for palmitoylation in the regulation of axons in health and disease. © 2017 Wiley Periodicals, Inc.
Collapse
Affiliation(s)
- Sabrina M Holland
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair)
| | - Gareth M Thomas
- Shriners Hospitals Pediatric Research Center (Center for Neurorehabilitation and Neural Repair).,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine at Temple University, 3500 N. Broad Street, Philadelphia, PA, 19140
| |
Collapse
|
361
|
Rapamycin-Resistant mTOR Activity Is Required for Sensory Axon Regeneration Induced by a Conditioning Lesion. eNeuro 2017; 3:eN-NWR-0358-16. [PMID: 28101526 PMCID: PMC5234127 DOI: 10.1523/eneuro.0358-16.2016] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 12/12/2016] [Indexed: 12/02/2022] Open
Abstract
Neuronal mammalian target of rapamycin (mTOR) activity is a critical determinant of the intrinsic regenerative ability of mature neurons in the adult central nervous system (CNS). However, whether its action also applies to peripheral nervous system (PNS) neurons after injury remains elusive. To address this issue unambiguously, we used genetic approaches to determine the role of mTOR signaling in sensory axon regeneration in mice. We showed that deleting mTOR in dorsal root ganglion (DRG) neurons suppressed the axon regeneration induced by conditioning lesions. To establish whether the impact of mTOR on axon regeneration results from functions of mTOR complex 1 (mTORC1) or 2 (mTORC2), two distinct kinase complexes, we ablated either Raptor or Rictor in DRG neurons. We found that suppressing mTORC1 signaling dramatically decreased the conditioning lesion effect. In addition, an injury to the peripheral branch boosts mTOR activity in DRG neurons that cannot be completely inhibited by rapamycin, a widely used mTOR-specific inhibitor. Unexpectedly, examining several conditioning lesion–induced pro-regenerative pathways revealed that Raptor deletion but not rapamycin suppressed Stat3 activity in neurons. Therefore, our results demonstrate that crosstalk between mTOR and Stat3 signaling mediates the conditioning lesion effect and provide genetic evidence that rapamycin-resistant mTOR activity contributes to the intrinsic axon growth capacity in adult sensory neurons after injury.
Collapse
|
362
|
Gwak SJ, Macks C, Jeong DU, Kindy M, Lynn M, Webb K, Lee JS. RhoA knockdown by cationic amphiphilic copolymer/siRhoA polyplexes enhances axonal regeneration in rat spinal cord injury model. Biomaterials 2017; 121:155-166. [PMID: 28088077 DOI: 10.1016/j.biomaterials.2017.01.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 12/22/2016] [Accepted: 01/02/2017] [Indexed: 01/06/2023]
Abstract
Spinal cord injury (SCI) results in permanent loss of motor and sensory function due to developmentally-related and injured-induced changes in the extrinsic microenvironment and intrinsic neuronal biochemistry that limit plasticity and axonal regeneration. Our long term goal is to develop cationic, amphiphilic copolymers (poly (lactide-co-glycolide)-g-polyethylenimine, PgP) for combinatorial delivery of therapeutic nucleic acids (TNAs) and drugs targeting these different barriers. In this study, we evaluated the ability of PgP to deliver siRNA targeting RhoA, a critical signaling pathway activated by multiple extracellular inhibitors of axonal regeneration. After generation of rat compression SCI model, PgP/siRhoA polyplexes were locally injected into the lesion site. Relative to untreated injury only, PgP/siRhoA polyplexes significantly reduced RhoA mRNA and protein expression for up to 4 weeks post-injury. Histological analysis at 4 weeks post-injury showed that RhoA knockdown was accompanied by reduced apoptosis, cavity size, and astrogliosis and increased axonal regeneration within the lesion site. These studies demonstrate that PgP is an efficient non-viral delivery carrier for therapeutic siRhoA to the injured spinal cord and may be a promising platform for the development of combinatorial TNA/drug therapy.
Collapse
Affiliation(s)
- So-Jung Gwak
- Drug Design, Development, and Delivery (4D) Laboratory, Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Christian Macks
- Drug Design, Development, and Delivery (4D) Laboratory, Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Da Un Jeong
- Drug Design, Development, and Delivery (4D) Laboratory, Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Mark Kindy
- Department of Pharmaceutical Sciences, College of Pharmacy, University of South Florida, Tampa, FL 33612, USA
| | - Michael Lynn
- Department of Neurosurgery, Greenville Health System, Greenville, SC 29615, USA
| | - Ken Webb
- Drug Design, Development, and Delivery (4D) Laboratory, Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
| | - Jeoung Soo Lee
- Drug Design, Development, and Delivery (4D) Laboratory, Department of Bioengineering, Clemson University, Clemson, SC 29634, USA.
| |
Collapse
|
363
|
Sullivan A, O'Keeffe G, Hegarty S. Targeting transcriptional regulators to regenerate midbrain dopaminergic axons in Parkinson's disease. Neural Regen Res 2017; 12:1814-1815. [PMID: 29239326 PMCID: PMC5745834 DOI: 10.4103/1673-5374.219039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
|
364
|
Tedeschi A, Bradke F. Spatial and temporal arrangement of neuronal intrinsic and extrinsic mechanisms controlling axon regeneration. Curr Opin Neurobiol 2016; 42:118-127. [PMID: 28039763 DOI: 10.1016/j.conb.2016.12.005] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 12/07/2016] [Accepted: 12/08/2016] [Indexed: 01/30/2023]
Abstract
Axon regeneration and neuronal tissue repair varies across animal lineages as well as in the mammalian central and peripheral nervous systems. While the peripheral nervous system retains the ability to self-repair, the majority of axons in the adult mammalian central nervous system (CNS) fail to reactivate intrinsic growth programs after injury. Recent findings, however, suggest that long-distance axon regeneration, neuronal circuit assembly and recovery of functions in the adult mammalian CNS are possible. Here, we discuss our current knowledge of the cell signaling pathways and networks controlling axon regeneration. In addition, we outline a number of combinatorial strategies that include among others microtubule-based treatments to foster regeneration and functional connectivity after CNS trauma.
Collapse
Affiliation(s)
- Andrea Tedeschi
- German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| | - Frank Bradke
- German Center for Neurodegenerative Diseases (DZNE), Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| |
Collapse
|
365
|
Inhibition of Poly-ADP-Ribosylation Fails to Increase Axonal Regeneration or Improve Functional Recovery after Adult Mammalian CNS Injury. eNeuro 2016; 3:eN-NRS-0270-16. [PMID: 28032120 PMCID: PMC5187389 DOI: 10.1523/eneuro.0270-16.2016] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 11/16/2016] [Accepted: 12/07/2016] [Indexed: 11/21/2022] Open
Abstract
After traumatic damage of the brain or spinal cord, many surviving neurons are disconnected, and recovery of function is limited by poor axon regeneration. Recent data have suggested that poly ADP-ribosylation plays a role in limiting axonal regrowth such that inhibition of poly (ADP-ribose) polymerase (PARP) may have therapeutic efficacy for neurological recovery after trauma. Here, we tested systemic administration of the PARP inhibitor, veliparib, and showed effective suppression of PARylation in the mouse CNS. After optic nerve crush injury or dorsal hemisection of the thoracic spinal cord in mice, treatment with veliparib at doses with pharmacodynamic action had no benefit for axonal regeneration or functional recovery. We considered whether PARP gene family specificity might play a role. In vitro mouse cerebral cortex axon regeneration experiments revealed that short hairpin RNA (shRNA)-mediated suppression of PARP1 promoted axonal regeneration, whereas suppression of other PARP isoforms either had no effect or decreased regeneration. Therefore, we examined recovery from neurological trauma in mice lacking PARP1. No increase of axonal regeneration was observed in Parp1–/– mice after optic nerve crush injury or dorsal hemisection of the thoracic spinal cord, and there was no improvement in motor function recovery. Thus, comprehensive in vivo analysis reveals no indication that clinical PARP inhibitors will on their own provide benefit for recovery from CNS trauma.
Collapse
|
366
|
Cartoni R, Norsworthy MW, Bei F, Wang C, Li S, Zhang Y, Gabel CV, Schwarz TL, He Z. The Mammalian-Specific Protein Armcx1 Regulates Mitochondrial Transport during Axon Regeneration. Neuron 2016; 92:1294-1307. [PMID: 28009275 PMCID: PMC5189716 DOI: 10.1016/j.neuron.2016.10.060] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 08/14/2016] [Accepted: 10/20/2016] [Indexed: 11/29/2022]
Abstract
Mitochondrial transport is crucial for neuronal and axonal physiology. However, whether and how it impacts neuronal injury responses, such as neuronal survival and axon regeneration, remain largely unknown. In an established mouse model with robust axon regeneration, we show that Armcx1, a mammalian-specific gene encoding a mitochondria-localized protein, is upregulated after axotomy in this high regeneration condition. Armcx1 overexpression enhances mitochondrial transport in adult retinal ganglion cells (RGCs). Importantly, Armcx1 also promotes both neuronal survival and axon regeneration after injury, and these effects depend on its mitochondrial localization. Furthermore, Armcx1 knockdown undermines both neuronal survival and axon regeneration in the high regenerative capacity model, further supporting a key role of Armcx1 in regulating neuronal injury responses in the adult central nervous system (CNS). Our findings suggest that Armcx1 controls mitochondrial transport during neuronal repair.
Collapse
Affiliation(s)
- Romain Cartoni
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA.
| | - Michael W Norsworthy
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Fengfeng Bei
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Chen Wang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Siwei Li
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Yiling Zhang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Christopher V Gabel
- Department of Physiology and Biophysics, Photonics Center, Boston University School of Medicine, Boston, MA 02118, USA
| | - Thomas L Schwarz
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA; Department of Neurobiology, Harvard Medical School, Boston, MA 02115, USA.
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, 300 Longwood Avenue, Boston, MA 02115, USA; Department of Neurology, Harvard Medical School, Boston, MA 02115, USA.
| |
Collapse
|
367
|
Merino P, Diaz A, Jeanneret V, Wu F, Torre E, Cheng L, Yepes M. Urokinase-type Plasminogen Activator (uPA) Binding to the uPA Receptor (uPAR) Promotes Axonal Regeneration in the Central Nervous System. J Biol Chem 2016; 292:2741-2753. [PMID: 27986809 DOI: 10.1074/jbc.m116.761650] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 12/15/2016] [Indexed: 11/06/2022] Open
Abstract
Axonal injury is a common cause of neurological dysfunction. Unfortunately, in contrast to axons from the peripheral nervous system, the limited capacity of regeneration of central nervous system (CNS) axons is a major obstacle for functional recovery in patients suffering neurological diseases that involve the subcortical white matter. Urokinase-type plasminogen activator (uPA) is a serine proteinase that upon binding to the urokinase-type plasminogen activator receptor (uPAR) catalyzes the conversion of plasminogen into plasmin on the cell surface. uPAR expression increases after an injury, and signaling through uPAR promotes tissue remodeling. However, it is yet unknown whether uPA binding to uPAR has an effect on axonal recovery in the CNS. Here, we used in vitro and in vivo models of CNS axonal injury to test the hypothesis that uPA binding to uPAR promotes axonal regeneration in the CNS. We found that newly formed growth cones from axons re-emerging from an axonal injury express uPAR and that binding of uPA to this uPAR promotes axonal recovery by a mechanism that does not require the generation of plasmin. Our data indicate that the binding of recombinant uPA or endogenous uPA to uPAR induces membrane recruitment and activation of β1 integrin via the low density lipoprotein receptor-related protein-1 (LRP1), which leads to activation of the Rho family small GTPase Rac1 and Rac1-induced axonal regeneration. Our results show that the uPA/uPAR/LRP1 system is a potential target for the development of therapeutic strategies to promote axonal recovery following a CNS injury.
Collapse
Affiliation(s)
- Paola Merino
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322.,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and
| | - Ariel Diaz
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322.,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and
| | - Valerie Jeanneret
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322.,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and
| | - Fang Wu
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322.,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and
| | - Enrique Torre
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322.,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and
| | - Lihong Cheng
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322.,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and
| | - Manuel Yepes
- From the Department of Neurology and Center for Neurodegenerative Disease, Emory University School of Medicine, Atlanta, Georgia 30322, .,the Division of Neurosciences, Yerkes National Primate Research Center, Atlanta, Georgia 30329, and.,the Department of Neurology, Veterans Affairs Medical Center, Atlanta, Georgia 30033
| |
Collapse
|
368
|
Affiliation(s)
- Philip R Williams
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA
| | - Zhigang He
- F.M. Kirby Neurobiology Center, Children's Hospital, and Department of Neurology, Harvard Medical School, 300 Longwood Avenue, Boston, MA 02115, USA.
| |
Collapse
|
369
|
Chisholm AD, Hutter H, Jin Y, Wadsworth WG. The Genetics of Axon Guidance and Axon Regeneration in Caenorhabditis elegans. Genetics 2016; 204:849-882. [PMID: 28114100 PMCID: PMC5105865 DOI: 10.1534/genetics.115.186262] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022] Open
Abstract
The correct wiring of neuronal circuits depends on outgrowth and guidance of neuronal processes during development. In the past two decades, great progress has been made in understanding the molecular basis of axon outgrowth and guidance. Genetic analysis in Caenorhabditis elegans has played a key role in elucidating conserved pathways regulating axon guidance, including Netrin signaling, the slit Slit/Robo pathway, Wnt signaling, and others. Axon guidance factors were first identified by screens for mutations affecting animal behavior, and by direct visual screens for axon guidance defects. Genetic analysis of these pathways has revealed the complex and combinatorial nature of guidance cues, and has delineated how cues guide growth cones via receptor activity and cytoskeletal rearrangement. Several axon guidance pathways also affect directed migrations of non-neuronal cells in C. elegans, with implications for normal and pathological cell migrations in situations such as tumor metastasis. The small number of neurons and highly stereotyped axonal architecture of the C. elegans nervous system allow analysis of axon guidance at the level of single identified axons, and permit in vivo tests of prevailing models of axon guidance. C. elegans axons also have a robust capacity to undergo regenerative regrowth after precise laser injury (axotomy). Although such axon regrowth shares some similarities with developmental axon outgrowth, screens for regrowth mutants have revealed regeneration-specific pathways and factors that were not identified in developmental screens. Several areas remain poorly understood, including how major axon tracts are formed in the embryo, and the function of axon regeneration in the natural environment.
Collapse
Affiliation(s)
| | - Harald Hutter
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Yishi Jin
- Section of Neurobiology, Division of Biological Sciences, and
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, California 92093
- Department of Pathology and Laboratory Medicine, Howard Hughes Medical Institute, Chevy Chase, Maryland, and
| | - William G Wadsworth
- Department of Pathology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey 08854
| |
Collapse
|
370
|
Extrinsic and Intrinsic Regulation of Axon Regeneration by MicroRNAs after Spinal Cord Injury. Neural Plast 2016; 2016:1279051. [PMID: 27818801 PMCID: PMC5081430 DOI: 10.1155/2016/1279051] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Revised: 09/02/2016] [Accepted: 09/21/2016] [Indexed: 02/07/2023] Open
Abstract
Spinal cord injury is a devastating disease which disrupts the connections between the brain and spinal cord, often resulting in the loss of sensory and motor function below the lesion site. Most injured neurons fail to regenerate in the central nervous system after injury. Multiple intrinsic and extrinsic factors contribute to the general failure of axonal regeneration after injury. MicroRNAs can modulate multiple genes' expression and are tightly controlled during nerve development or the injury process. Evidence has demonstrated that microRNAs and their signaling pathways play important roles in mediating axon regeneration and glial scar formation after spinal cord injury. This article reviews the role and mechanism of differentially expressed microRNAs in regulating axon regeneration and glial scar formation after spinal cord injury, as well as their therapeutic potential for promoting axonal regeneration and repair of the injured spinal cord.
Collapse
|
371
|
Synapse-Specific Reinnervation in the Injured Brain. J Neurosci 2016; 36:10239-10241. [PMID: 27707961 DOI: 10.1523/jneurosci.2041-16.2016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 08/23/2016] [Indexed: 11/21/2022] Open
|
372
|
Barber A, Farmer K, Martin KR, Smith PD. Retinal regeneration mechanisms linked to multiple cancer molecules: A therapeutic conundrum. Prog Retin Eye Res 2016; 56:19-31. [PMID: 27586058 DOI: 10.1016/j.preteyeres.2016.08.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Revised: 03/06/2016] [Accepted: 03/07/2016] [Indexed: 11/26/2022]
Abstract
Over the last decade, a large number of research articles have been published demonstrating regeneration and/or neuroprotection of retinal ganglion cells following manipulation of specific genetic and molecular targets. Interestingly, of the targets that have been identified to promote repair following visual system damage, many are genes known to be mutated in different types of cancer. This review explores recent literature on the potential for modulating cancer genes as a therapeutic strategy for visual system repair and looks at the potential clinical challenges associated with implementing this type of therapy. We also discuss signalling mechanisms that have been implicated in cancer and consider how similar mechanisms may improve axonal regeneration in the optic nerve.
Collapse
Affiliation(s)
- Amanda Barber
- John van Geest Centre for Brain Repair, University of Cambridge, UK
| | - Kyle Farmer
- Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada
| | - Keith R Martin
- John van Geest Centre for Brain Repair, University of Cambridge, UK; Medical Research Council - Wellcome Trust Cambridge Stem Cell Institute, Cambridge, UK; Cambridge NIHR Biomedical Research Centre, Cambridge, UK
| | - Patrice D Smith
- John van Geest Centre for Brain Repair, University of Cambridge, UK; Department of Neuroscience, Carleton University, Ottawa, Ontario, Canada.
| |
Collapse
|
373
|
Zhang Z, Chopp M. Neural Stem Cells and Ischemic Brain. J Stroke 2016; 18:267-272. [PMID: 27488979 PMCID: PMC5066435 DOI: 10.5853/jos.2016.00206] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/13/2016] [Accepted: 05/18/2016] [Indexed: 01/19/2023] Open
Abstract
Stroke activates neural stem cells in the ventricular-subventricular zone (V/SVZ) of the lateral ventricle, which increases neuroblasts and oligodendrocyte progenitor cells (OPCs). Within the ischemic brain, neural stem cells, neuroblasts and OPCs appear to actively communicate with cerebral endothelial cells and other brain parenchymal cells to mediate ischemic brain repair; however, stroke-induced neurogenesis unlikely plays any significant roles in neuronal replacement. In this mini-review, we will discuss recent findings how intercellular communications between stroke-induced neurogenesis and oligodendrogenesis and brain parenchymal cells could potentially facilitate brain repair processes.
Collapse
Affiliation(s)
| | - Michael Chopp
- Henry Ford Hospital, Michigan, United States.,Department of Physics, Oakland University, Rochester, Michigan, United States
| |
Collapse
|
374
|
Affiliation(s)
- Jacek Krol
- Neural Circuit Laboratories, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland, and
| | - Botond Roska
- Neural Circuit Laboratories, Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland, and.,University of Basel, Basel, Switzerland
| |
Collapse
|
375
|
Kramer NJ, Gitler AD. Regrowing axons with alternative splicing. eLife 2016; 5. [PMID: 27420813 PMCID: PMC4946881 DOI: 10.7554/elife.18707] [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: 07/11/2016] [Accepted: 07/11/2016] [Indexed: 11/13/2022] Open
Abstract
The regeneration of axons relies on a previously unknown mechanism that involves the regulation of alternative splicing by CELF proteins.
Collapse
Affiliation(s)
- Nicholas J Kramer
- Department of Genetics and the Neurosciences Graduate Program, Stanford University School of Medicine, Stanford, United States
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, United States
| |
Collapse
|