101
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Girouard MP, Bueno M, Julian V, Drake S, Byrne AB, Fournier AE. The Molecular Interplay between Axon Degeneration and Regeneration. Dev Neurobiol 2018; 78:978-990. [PMID: 30022605 DOI: 10.1002/dneu.22627] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/29/2018] [Accepted: 06/04/2018] [Indexed: 12/30/2022]
Abstract
Neurons face a series of morphological and molecular changes following trauma and in the progression of neurodegenerative disease. In neurons capable of mounting a spontaneous regenerative response, including invertebrate neurons and mammalian neurons of the peripheral nervous system (PNS), axons regenerate from the proximal side of the injury and degenerate on the distal side. Studies of Wallerian degeneration slow (WldS /Ola) mice have revealed that a level of coordination between the processes of axon regeneration and degeneration occurs during successful repair. Here, we explore how shared cellular and molecular pathways that regulate both axon regeneration and degeneration coordinate the two distinct outcomes in the proximal and distal axon segments. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Marie-Pier Girouard
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
| | - Mardja Bueno
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
| | - Victoria Julian
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Sienna Drake
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
| | - Alexandra B Byrne
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655
| | - Alyson E Fournier
- Department of Neurology & Neurosurgery, Montréal Neurological Institute, Montréal, Quebec H3A 2B4, Canada
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102
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Eisner V, Picard M, Hajnóczky G. Mitochondrial dynamics in adaptive and maladaptive cellular stress responses. Nat Cell Biol 2018; 20:755-765. [PMID: 29950571 PMCID: PMC6716149 DOI: 10.1038/s41556-018-0133-0] [Citation(s) in RCA: 361] [Impact Index Per Article: 60.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Accepted: 05/29/2018] [Indexed: 12/22/2022]
Abstract
Mitochondria sense and respond to many stressors and can support either cell survival or death through energy production and signaling pathways. Mitochondrial responses depend on fusion-fission dynamics that dilute and segregate damaged mitochondria. Mitochondrial motility and inter-organellar interactions, including with the endoplasmic reticulum, also function in cellular adaptation to stress. In this Review, we discuss how stressors influence these components, and how they contribute to the complex adaptive and pathological responses that lead to disease.
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Affiliation(s)
- Verónica Eisner
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Martin Picard
- Division of Behavioral Medicine, Departments of Psychiatry and Neurology, The Merritt Center, Columbia Translational Neuroscience Initiative, Columbia Aging Center, Columbia University Medical Center, New York, NY, USA
| | - György Hajnóczky
- MitoCare Center, Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, Philadelphia, PA, USA.
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103
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Murillo B, Mendes Sousa M. Neuronal Intrinsic Regenerative Capacity: The Impact of Microtubule Organization and Axonal Transport. Dev Neurobiol 2018; 78:952-959. [PMID: 29738096 DOI: 10.1002/dneu.22602] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/20/2018] [Accepted: 04/25/2018] [Indexed: 11/06/2022]
Abstract
In the adult vertebrate central nervous system, axons generally fail to regenerate. In contrast, peripheral nervous system axons are able to form a growth cone and regenerate upon lesion. Among the multiple intrinsic mechanisms leading to the formation of a new growth cone and to successful axon regrowth, cytoskeleton organization and dynamics is central. Here we discuss how multiple pathways that define the regenerative capacity converge into the regulation of the axonal microtubule cytoskeleton and transport. We further explore the use of dorsal root ganglion neurons as a model to study the neuronal regenerative ability. Finally, we address some of the unanswered questions in the field, including the mechanisms by which axonal transport might be modulated by injury, and the relationship between microtubule organization, dynamics, and axonal transport. © 2018 Wiley Periodicals, Inc. Develop Neurobiol 00: 000-000, 2018.
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Affiliation(s)
- Blanca Murillo
- Nerve Regeneration group, Instituto de Biologia Molecular e Celular - IBMC and Instituto de Inovação e Investigação em Saúde, University of Porto, Rua Alfredo Allen 208, Porto, 4200-135, Portugal
| | - Mónica Mendes Sousa
- Nerve Regeneration group, Instituto de Biologia Molecular e Celular - IBMC and Instituto de Inovação e Investigação em Saúde, University of Porto, Rua Alfredo Allen 208, Porto, 4200-135, Portugal
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104
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Vagnoni A, Bullock SL. A cAMP/PKA/Kinesin-1 Axis Promotes the Axonal Transport of Mitochondria in Aging Drosophila Neurons. Curr Biol 2018; 28:1265-1272.e4. [PMID: 29606421 PMCID: PMC5912900 DOI: 10.1016/j.cub.2018.02.048] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 01/10/2018] [Accepted: 02/19/2018] [Indexed: 11/15/2022]
Abstract
Mitochondria play fundamental roles within cells, including energy provision, calcium homeostasis, and the regulation of apoptosis. The transport of mitochondria by microtubule-based motors is critical for neuronal structure and function. This process allows local requirements for mitochondrial functions to be met and also facilitates recycling of these organelles [1, 2]. An age-related reduction in mitochondrial transport has been observed in neurons of mammalian and non-mammalian organisms [3, 4, 5, 6], and has been proposed to contribute to the broader decline in neuronal function that occurs during aging [3, 5, 6, 7]. However, the factors that influence mitochondrial transport in aging neurons are poorly understood. Here we provide evidence using the tractable Drosophila wing nerve system that the cyclic AMP/protein kinase A (cAMP/PKA) pathway promotes the axonal transport of mitochondria in adult neurons. The level of the catalytic subunit of PKA decreases during aging, and acute activation of the cAMP/PKA pathway in aged flies strongly stimulates mitochondrial motility. Thus, the age-related impairment of transport is reversible. The expression of many genes is increased by PKA activation in aged flies. However, our results indicate that elevated mitochondrial transport is due in part to upregulation of the heavy chain of the kinesin-1 motor, the level of which declines during aging. Our study identifies evolutionarily conserved factors that can strongly influence mitochondrial motility in aging neurons. cAMP/PKA pathway promotes mitochondrial transport in adult Drosophila wing neurons Pathway activation in aged flies suppresses age-related reduction in transport Levels of PKAc and kinesin-1 motor decline during aging Kinesin-1 upregulation is an important output of PKA activation in aged flies
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Affiliation(s)
- Alessio Vagnoni
- Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK; Department of Basic and Clinical Neuroscience, Maurice Wohl Clinical Neuroscience Institute, King's College London, London SE5 9RX, UK.
| | - Simon L Bullock
- Division of Cell Biology, MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK.
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105
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Carelli V, La Morgia C, Ross-Cisneros FN, Sadun AA. Optic neuropathies: the tip of the neurodegeneration iceberg. Hum Mol Genet 2018; 26:R139-R150. [PMID: 28977448 PMCID: PMC5886475 DOI: 10.1093/hmg/ddx273] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 07/10/2017] [Indexed: 01/06/2023] Open
Abstract
The optic nerve and the cells that give origin to its 1.2 million axons, the retinal ganglion cells (RGCs), are particularly vulnerable to neurodegeneration related to mitochondrial dysfunction. Optic neuropathies may range from non-syndromic genetic entities, to rare syndromic multisystem diseases with optic atrophy such as mitochondrial encephalomyopathies, to age-related neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease where optic nerve involvement has, until recently, been a relatively overlooked feature. New tools are available to thoroughly investigate optic nerve function, allowing unparalleled access to this part of the central nervous system. Understanding the molecular pathophysiology of RGC neurodegeneration and optic atrophy, is key to broadly understanding the pathogenesis of neurodegenerative disorders, for monitoring their progression in describing the natural history, and ultimately as outcome measures to evaluate therapies. In this review, the different layers, from molecular to anatomical, that may contribute to RGC neurodegeneration and optic atrophy are tackled in an integrated way, considering all relevant players. These include RGC dendrites, cell bodies and axons, the unmyelinated retinal nerve fiber layer and the myelinated post-laminar axons, as well as olygodendrocytes and astrocytes, looked for unconventional functions. Dysfunctional mitochondrial dynamics, transport, homeostatic control of mitobiogenesis and mitophagic removal, as well as specific propensity to apoptosis may target differently cell types and anatomical settings. Ultimately, we can envisage new investigative approaches and therapeutic options that will speed the early diagnosis of neurodegenerative diseases and their cure.
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Affiliation(s)
- Valerio Carelli
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Chiara La Morgia
- IRCCS Institute of Neurological Sciences of Bologna, Bellaria Hospital, Bologna, Italy.,Department of Biomedical and Neuromotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | | | - Alfredo A Sadun
- Doheny Eye Institute, Los Angeles, CA 90033, USA.,Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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106
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Wang H, Xiao C, Dong D, Lin C, Xue Y, Liu J, Wu M, He J, Fu T, Pan H, Jiao X, Lu D, Li Z. Epothilone B Speeds Corneal Nerve Regrowth and Functional Recovery through Microtubule Stabilization and Increased Nerve Beading. Sci Rep 2018; 8:2647. [PMID: 29422528 PMCID: PMC5805685 DOI: 10.1038/s41598-018-20734-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 01/23/2018] [Indexed: 12/13/2022] Open
Abstract
The successful restoration of corneal innervation and function after a corneal injury is a clinically challenging issue. Structural and functional recovery after a nerve injury involves a complex series of steps in which microtubules play a key role. The aim of the current study was to investigate the effects of epothilone B (EpoB), a microtubule-stabilizing agent, on corneal innervation and the functional recovery of the corneal nerve in mice after corneal epithelial abrasion. The pretreatment of mice with EpoB has a remarkable effect on the stabilization of beta-III tubulin, as demonstrated by substantial increases in the visualization of beta-III tubulin, nerve beading, corneal reinnervation, and reaction to stimuli. Furthermore, a pharmacokinetic analysis showed that EpoB remains at a high concentration in the cornea and the trigeminal ganglion for at least 6 days after administration. In addition, the administration of EpoB at 24 hours after corneal abrasion has a marked therapeutic effect on nerve regrowth and functional recovery. In conclusion, EpoB treatment may have therapeutic utility for improving corneal reinnervation and restoring sensitivity following corneal injury.
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Affiliation(s)
- Hanqing Wang
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Chengju Xiao
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Dong Dong
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Cuipei Lin
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Yunxia Xue
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Jun Liu
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Mingjuan Wu
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Jingxin He
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Ting Fu
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Hongwei Pan
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China
| | - Xinwei Jiao
- Henan Key Laboratory of Ophthalmology and Visual Science, People's Hospital of Zhengzhou University, Henan University School of Medicine, Henan Provincial People's Hospital, Zhengzhou, China
| | - Dingli Lu
- Henan Key Laboratory of Ophthalmology and Visual Science, People's Hospital of Zhengzhou University, Henan University School of Medicine, Henan Provincial People's Hospital, Zhengzhou, China
| | - Zhijie Li
- International Ocular Surface Research Center, Institute of Ophthalmology, Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China. .,Henan Key Laboratory of Ophthalmology and Visual Science, People's Hospital of Zhengzhou University, Henan University School of Medicine, Henan Provincial People's Hospital, Zhengzhou, China. .,Department of Immunology and Microbiology, Jinan University Medical School, Guangzhou, China. .,Section of Leukocyte Biology, Department of Pediatrics, Children's Nutrition Research Center, Baylor College of Medicine, Houston, Texas, USA.
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107
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López-Doménech G, Covill-Cooke C, Ivankovic D, Halff EF, Sheehan DF, Norkett R, Birsa N, Kittler JT. Miro proteins coordinate microtubule- and actin-dependent mitochondrial transport and distribution. EMBO J 2018; 37:321-336. [PMID: 29311115 PMCID: PMC5793800 DOI: 10.15252/embj.201696380] [Citation(s) in RCA: 207] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 11/24/2017] [Accepted: 12/04/2017] [Indexed: 11/28/2022] Open
Abstract
In the current model of mitochondrial trafficking, Miro1 and Miro2 Rho-GTPases regulate mitochondrial transport along microtubules by linking mitochondria to kinesin and dynein motors. By generating Miro1/2 double-knockout mouse embryos and single- and double-knockout embryonic fibroblasts, we demonstrate the essential and non-redundant roles of Miro proteins for embryonic development and subcellular mitochondrial distribution. Unexpectedly, the TRAK1 and TRAK2 motor protein adaptors can still localise to the outer mitochondrial membrane to drive anterograde mitochondrial motility in Miro1/2 double-knockout cells. In contrast, we show that TRAK2-mediated retrograde mitochondrial transport is Miro1-dependent. Interestingly, we find that Miro is critical for recruiting and stabilising the mitochondrial myosin Myo19 on the mitochondria for coupling mitochondria to the actin cytoskeleton. Moreover, Miro depletion during PINK1/Parkin-dependent mitophagy can also drive a loss of mitochondrial Myo19 upon mitochondrial damage. Finally, aberrant positioning of mitochondria in Miro1/2 double-knockout cells leads to disruption of correct mitochondrial segregation during mitosis. Thus, Miro proteins can fine-tune actin- and tubulin-dependent mitochondrial motility and positioning, to regulate key cellular functions such as cell proliferation.
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Affiliation(s)
| | - Christian Covill-Cooke
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Davor Ivankovic
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Els F Halff
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - David F Sheehan
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Rosalind Norkett
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Nicol Birsa
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
| | - Josef T Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, UK
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108
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Misgeld T, Schwarz TL. Mitostasis in Neurons: Maintaining Mitochondria in an Extended Cellular Architecture. Neuron 2017; 96:651-666. [PMID: 29096078 DOI: 10.1016/j.neuron.2017.09.055] [Citation(s) in RCA: 309] [Impact Index Per Article: 44.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 09/25/2017] [Accepted: 09/28/2017] [Indexed: 02/06/2023]
Abstract
Neurons have more extended and complex shapes than other cells and consequently face a greater challenge in distributing and maintaining mitochondria throughout their arbors. Neurons can last a lifetime, but proteins turn over rapidly. Mitochondria, therefore, need constant rejuvenation no matter how far they are from the soma. Axonal transport of mitochondria and mitochondrial fission and fusion contribute to this rejuvenation, but local protein synthesis is also likely. Maintenance of a healthy mitochondrial population also requires the clearance of damaged proteins and organelles. This involves degradation of individual proteins, sequestration in mitochondria-derived vesicles, organelle degradation by mitophagy and macroautophagy, and in some cases transfer to glial cells. Both long-range transport and local processing are thus at work in achieving neuronal mitostasis-the maintenance of an appropriately distributed pool of healthy mitochondria for the duration of a neuron's life. Accordingly, defects in the processes that support mitostasis are significant contributors to neurodegenerative disorders.
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Affiliation(s)
- Thomas Misgeld
- Technical University of Munich, Institute of Neuronal Cell Biology, Munich, Germany; German Center for Neurodegenerative Diseases, Munich, Germany; Munich Cluster for Systems Neurology, Munich, Germany; Center of Integrated Protein Science, Munich, Germany.
| | - Thomas L Schwarz
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA; F.M. Kirby Neurobiology Center, Children's Hospital, Boston, MA, USA.
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109
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Abstract
In this issue of Neuron, Han et al. (2016) and Cartoni et al. (2016) define a critical role of mitochondrial transport for successful axon regeneration after injury and provide new insights into intrinsic mechanisms controlling neuronal regeneration capacity in worms and mice.
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Affiliation(s)
- Lilian A Patrón
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA; Graduate Interdisciplinary Program in Neuroscience, University of Arizona, Tucson, AZ 85721, USA
| | - Konrad E Zinsmaier
- Department of Neuroscience, University of Arizona, Tucson, AZ 85721, USA; Department of Molecular and Cellular Biology, University of Arizona, Tucson, AZ 85721, USA.
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110
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Smith GM, Gallo G. The role of mitochondria in axon development and regeneration. Dev Neurobiol 2017; 78:221-237. [PMID: 29030922 DOI: 10.1002/dneu.22546] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Revised: 09/12/2017] [Accepted: 10/08/2017] [Indexed: 12/26/2022]
Abstract
Mitochondria are dynamic organelles that undergo transport, fission, and fusion. The three main functions of mitochondria are to generate ATP, buffer cytosolic calcium, and generate reactive oxygen species. A large body of evidence indicates that mitochondria are either primary targets for neurological disease states and nervous system injury, or are major contributors to the ensuing pathologies. However, the roles of mitochondria in the development and regeneration of axons have just begun to be elucidated. Advances in the understanding of the functional roles of mitochondria in neurons had been largely impeded by insufficient knowledge regarding the molecular mechanisms that regulate mitochondrial transport, stalling, fission/fusion, and a paucity of approaches to image and analyze mitochondria in living axons at the level of the single mitochondrion. However, technical advances in the imaging and analysis of mitochondria in living neurons and significant insights into the mechanisms that regulate mitochondrial dynamics have allowed the field to advance. Mitochondria have now been attributed important roles in the mechanism of axon extension, regeneration, and axon branching. The availability of new experimental tools is expected to rapidly increase our understanding of the functions of axonal mitochondria during both development and later regenerative attempts. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 221-237, 2018.
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Affiliation(s)
- George M Smith
- Department of Neuroscience, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140.,Shriners Hospitals Pediatric Research Center, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140.,Shriners Hospitals Pediatric Research Center, Temple University, Lewis Katz School of Medicine, Philadelphia, Pennsylvania, 19140
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111
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Hilton BJ, Bradke F. Can injured adult CNS axons regenerate by recapitulating development? Development 2017; 144:3417-3429. [PMID: 28974639 DOI: 10.1242/dev.148312] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In the adult mammalian central nervous system (CNS), neurons typically fail to regenerate their axons after injury. During development, by contrast, neurons extend axons effectively. A variety of intracellular mechanisms mediate this difference, including changes in gene expression, the ability to form a growth cone, differences in mitochondrial function/axonal transport and the efficacy of synaptic transmission. In turn, these intracellular processes are linked to extracellular differences between the developing and adult CNS. During development, the extracellular environment directs axon growth and circuit formation. In adulthood, by contrast, extracellular factors, such as myelin and the extracellular matrix, restrict axon growth. Here, we discuss whether the reactivation of developmental processes can elicit axon regeneration in the injured CNS.
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Affiliation(s)
- Brett J Hilton
- Laboratory for Axon Growth and Regeneration, German Centre for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
| | - Frank Bradke
- Laboratory for Axon Growth and Regeneration, German Centre for Neurodegenerative Diseases (DZNE), Sigmund-Freud-Strasse 27, 53127, Bonn, Germany
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112
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Sainath R, Armijo-Weingart L, Ketscheck A, Xu Z, Li S, Gallo G. Chondroitin sulfate proteoglycans negatively regulate the positioning of mitochondria and endoplasmic reticulum to distal axons. Dev Neurobiol 2017; 77:1351-1370. [PMID: 28901718 DOI: 10.1002/dneu.22535] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 08/23/2017] [Accepted: 09/08/2017] [Indexed: 12/20/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) are components of the extracellular matrix that inhibit the extension and regeneration of axons. However, the underlying mechanism of action remains poorly understood. Mitochondria and endoplasmic reticulum (ER) are functionally inter-linked organelles important to axon development and maintenance. We report that CSPGs impair the targeting of mitochondria and ER to the growth cones of chicken embryonic sensory axons. The effect of CSPGs on the targeting of mitochondria is blocked by inhibition of the LAR receptor for CSPGs. The regulation of the targeting of mitochondria and ER to the growth cone by CSPGs is due to attenuation of PI3K signaling, which is known to be downstream of LAR receptor activation. Dynactin is a required component of the dynein motor complex that drives the normally occurring retrograde evacuation of mitochondria from growth cones. CSPGs elevate the levels of p150Glu dynactin found in distal axons, and inhibition of the interaction of dynactin with dynein increased axon lengths on CSPGs. CSPGs decreased the membrane potential of mitochondria, and pharmacological inhibition of mitochondria respiration at the growth cone independent of manipulation of mitochondria positioning impaired axon extension. Combined inhibition of dynactin and potentiation of mitochondria respiration further increased axon lengths on CSPGs relative to inhibition of dynactin alone. These data reveal that the regulation of the localization of mitochondria and ER to growth cones is a previously unappreciated aspect of the effects of CSPGs on embryonic axons. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1351-1370, 2017.
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Affiliation(s)
- Rajiv Sainath
- Department of Anatomy and Cell Biology, Medical Education and Research Building, 3500 North Brad St, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Lorena Armijo-Weingart
- Department of Anatomy and Cell Biology, Medical Education and Research Building, 3500 North Brad St, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Andrea Ketscheck
- Department of Anatomy and Cell Biology, Medical Education and Research Building, 3500 North Brad St, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Zhuxuan Xu
- Department of Anatomy and Cell Biology, Medical Education and Research Building, 3500 North Brad St, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Shuxin Li
- Department of Anatomy and Cell Biology, Medical Education and Research Building, 3500 North Brad St, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Medical Education and Research Building, 3500 North Brad St, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
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113
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Cartoni R, Pekkurnaz G, Wang C, Schwarz TL, He Z. A high mitochondrial transport rate characterizes CNS neurons with high axonal regeneration capacity. PLoS One 2017; 12:e0184672. [PMID: 28926622 PMCID: PMC5604968 DOI: 10.1371/journal.pone.0184672] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 08/28/2017] [Indexed: 12/26/2022] Open
Abstract
Improving axonal transport in the injured and diseased central nervous system has been proposed as a promising strategy to improve neuronal repair. However, the contribution of each cargo to the repair mechanism is unknown. DRG neurons globally increase axonal transport during regeneration. Because the transport of specific cargos after axonal insult has not been examined systematically in a model of enhanced regenerative capacity, it is unknown whether the transport of all cargos would be modulated equally in injured central nervous system neurons. Here, using a microfluidic culture system we compared neurons co-deleted for PTEN and SOCS3, an established model of high axonal regeneration capacity, to control neurons. We measured the axonal transport of three cargos (mitochondria, synaptic vesicles and late endosomes) in regenerating axons and found that the transport of mitochondria, but not the other cargos, was increased in PTEN/SOCS3 co-deleted axons relative to controls. The results reported here suggest a pivotal role for this organelle during axonal regeneration.
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Affiliation(s)
- Romain Cartoni
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Gulcin Pekkurnaz
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chen Wang
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Thomas L. Schwarz
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (ZH); (TLS)
| | - Zhigang He
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, Massachusetts, United States of America
- Department of Neurology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (ZH); (TLS)
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114
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Kaplan A, Morquette B, Kroner A, Leong S, Madwar C, Sanz R, Banerjee SL, Antel J, Bisson N, David S, Fournier AE. Small-Molecule Stabilization of 14-3-3 Protein-Protein Interactions Stimulates Axon Regeneration. Neuron 2017; 93:1082-1093.e5. [PMID: 28279353 DOI: 10.1016/j.neuron.2017.02.018] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Revised: 01/11/2017] [Accepted: 02/07/2017] [Indexed: 12/19/2022]
Abstract
Damaged central nervous system (CNS) neurons have a poor ability to spontaneously regenerate, causing persistent functional deficits after injury. Therapies that stimulate axon growth are needed to repair CNS damage. 14-3-3 adaptors are hub proteins that are attractive targets to manipulate cell signaling. We identify a positive role for 14-3-3s in axon growth and uncover a developmental regulation of the phosphorylation and function of 14-3-3s. We show that fusicoccin-A (FC-A), a small-molecule stabilizer of 14-3-3 protein-protein interactions, stimulates axon growth in vitro and regeneration in vivo. We show that FC-A stabilizes a complex between 14-3-3 and the stress response regulator GCN1, inducing GCN1 turnover and neurite outgrowth. These findings show that 14-3-3 adaptor protein complexes are druggable targets and identify a new class of small molecules that may be further optimized for the repair of CNS damage.
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Affiliation(s)
- Andrew Kaplan
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Barbara Morquette
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Antje Kroner
- Department of Neurosurgery, Medical College of Wisconsin, VA Medical Center, Milwaukee, WI 53295, USA; Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montréal, QC H3G 1A4, Canada
| | - SooYuen Leong
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Carolin Madwar
- Department of Chemistry, McGill University, Montréal, QC H3A 0B8, Canada
| | - Ricardo Sanz
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Sara L Banerjee
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, and Centre de Recherche sur le Cancer, Université Laval, Québec City, QC G1V 0A6, Canada
| | - Jack Antel
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada
| | - Nicolas Bisson
- Département de Biologie Moléculaire, Biochimie Médicale et Pathologie, and Centre de Recherche sur le Cancer, Université Laval, Québec City, QC G1V 0A6, Canada
| | - Samuel David
- Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montréal, QC H3G 1A4, Canada
| | - Alyson E Fournier
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, QC H3A 2B4, Canada.
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115
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Chen J, Wang Z, Mao Y, Zheng Z, Chen Y, Khor S, Shi K, He Z, Li J, Gong F, Liu Y, Hu A, Xiao J, Wang X. Liraglutide activates autophagy via GLP-1R to improve functional recovery after spinal cord injury. Oncotarget 2017; 8:85949-85968. [PMID: 29156769 PMCID: PMC5689659 DOI: 10.18632/oncotarget.20791] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 07/13/2017] [Indexed: 12/18/2022] Open
Abstract
Therapeutics used to treat central nervous system (CNS) injury are designed to promote axonal regeneration and inhibit cell death. Previous studies have shown that liraglutide exerts potent neuroprotective effects after brain injury. However, little is known if liraglutide treatment has neuroprotective effects after spinal cord injury (SCI). This study explores the neuroprotective effects of liraglutide and associated underlying mechanisms. Our results showed that liraglutide could improve recovery after injury by decreasing apoptosis as well as increasing microtubulin acetylation, and autophagy. Autophagy inhibition with 3-methyladenine (3-MA) partially reversed the preservation of spinal cord tissue and decreased microtubule acetylation and polymerization. Additionally, siRNA knockdown of GLP-1R suppressed autophagy and reversed mTOR inhibition induced by liraglutide in vitro, indicating that GLP-1R regulates autophagic flux. GLP-1R knockdown ameliorated the mTOR inhibition and autophagy induction seen with liraglutide treatment in PC12 cells under H2O2 stimulation. Taken together, our study demonstrated that liraglutide could reduce apoptosis, improve functional recovery, and increase microtubule acetylation via autophagy stimulation after SCI. GLP-1R was associated with both the induction of autophagy and suppression of apoptosis in neuronal cultures.
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Affiliation(s)
- Jian Chen
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zhouguang Wang
- Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yuqin Mao
- Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Zengming Zheng
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yu Chen
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Sinan Khor
- Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, NY, U.S.A
| | - Kesi Shi
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zili He
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jiawei Li
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Fanghua Gong
- Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yanlong Liu
- Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Aiping Hu
- Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Jian Xiao
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China.,Molecular Pharmacology Research Center, School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xiangyang Wang
- Department of Orthopaedic Surgery, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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116
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Han SM, Baig HS, Hammarlund M. Mitochondria Localize to Injured Axons to Support Regeneration. Neuron 2017; 92:1308-1323. [PMID: 28009276 DOI: 10.1016/j.neuron.2016.11.025] [Citation(s) in RCA: 158] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 08/31/2016] [Accepted: 11/08/2016] [Indexed: 12/19/2022]
Abstract
Axon regeneration is essential to restore the nervous system after axon injury. However, the neuronal cell biology that underlies axon regeneration is incompletely understood. Here we use in vivo, single-neuron analysis to investigate the relationship between nerve injury, mitochondrial localization, and axon regeneration. Mitochondria translocate into injured axons so that average mitochondria density increases after injury. Moreover, single-neuron analysis reveals that axons that fail to increase mitochondria have poor regeneration. Experimental alterations to axonal mitochondrial distribution or mitochondrial respiratory chain function result in corresponding changes to regeneration outcomes. Axonal mitochondria are specifically required for growth-cone migration, identifying a key energy challenge for injured neurons. Finally, mitochondrial localization to the axon after injury is regulated in part by dual-leucine zipper kinase 1 (DLK-1), a conserved regulator of axon regeneration. These data identify regulation of axonal mitochondria as a new cell-biological mechanism that helps determine the regenerative response of injured neurons.
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Affiliation(s)
- Sung Min Han
- Departments of Genetics and Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA
| | - Huma S Baig
- Departments of Genetics and Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA
| | - Marc Hammarlund
- Departments of Genetics and Neuroscience, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
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117
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Kaplan A, Bueno M, Hua L, Fournier AE. Maximizing functional axon repair in the injured central nervous system: Lessons from neuronal development. Dev Dyn 2017. [PMID: 28643358 DOI: 10.1002/dvdy.24536] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The failure of damaged axons to regrow underlies disability in central nervous system injury and disease. Therapies that stimulate axon repair will be critical to restore function. Extensive axon regeneration can be induced by manipulation of oncogenes and tumor suppressors; however, it has been difficult to translate this into functional recovery in models of spinal cord injury. The current challenge is to maximize the functional integration of regenerating axons to recover motor and sensory behaviors. Insights into axonal growth and wiring during nervous system development are helping guide new approaches to boost regeneration and functional connectivity after injury in the mature nervous system. Here we discuss our current understanding of axonal behavior after injury and prospects for the development of drugs to optimize axon regeneration and functional recovery after CNS injury. Developmental Dynamics 247:18-23, 2018. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Andrew Kaplan
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Mardja Bueno
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Luyang Hua
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada
| | - Alyson E Fournier
- Department of Neurology and Neurosurgery, Montréal Neurological Institute, McGill University, Montréal, Québec, Canada
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118
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Damage-induced neuronal endopeptidase (DINE) enhances axonal regeneration potential of retinal ganglion cells after optic nerve injury. Cell Death Dis 2017; 8:e2847. [PMID: 28569783 PMCID: PMC5520884 DOI: 10.1038/cddis.2017.212] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Revised: 04/06/2017] [Accepted: 04/10/2017] [Indexed: 01/22/2023]
Abstract
Damage-induced neuronal endopeptidase (DINE)/endothelin-converting enzyme-like 1 (ECEL1) is a membrane-bound metalloprotease that we identified as a nerve regeneration-associated molecule. The expression of DINE is upregulated in response to nerve injury in both the peripheral and central nervous systems, while its transcription is regulated by the activating transcription factor 3 (ATF3), a potent hub-transcription factor for nerve regeneration. Despite its unique hallmark of injury-induced upregulation, the physiological relevance of DINE in injured neurons has been unclear. In this study, we have demonstrated that the expression of DINE is upregulated in injured retinal ganglion cells (RGCs) in a coordinated manner with that of ATF3 after optic nerve injury, whereas DINE and ATF3 are not observed in any normal retinal cells. Recently, we have generated a mature DINE-deficient (KOTg) mouse, in which exogenous DINE is overexpressed specifically in embryonic motor neurons to avoid aberrant arborization of motor nerves and lethality after birth that occurs in the conventional DINE KO mouse. The DINE KOTg mice did not show any difference in retinal structure and the projection to brain from that of wild–type (wild type) mice under normal conditions. However, injured RGCs of DINE KOTg mice failed to regenerate even after the zymosan treatment, which is a well-known regeneration-promoting reagent. Furthermore, a DINE KOTg mouse crossed with a Atf3:BAC Tg mouse, in which green fluorescent protein (GFP) is visualized specifically in injured RGCs and optic nerves, has verified that DINE deficiency leads to regeneration failure. These findings suggest that injury-induced DINE is a crucial endopeptidase for injured RGCs to promote axonal regeneration after optic nerve injury. Thus, a DINE-mediated proteolytic mechanism would provide us with a new therapeutic strategy for nerve regeneration.
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119
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Sheng ZH. The Interplay of Axonal Energy Homeostasis and Mitochondrial Trafficking and Anchoring. Trends Cell Biol 2017; 27:403-416. [PMID: 28228333 PMCID: PMC5440189 DOI: 10.1016/j.tcb.2017.01.005] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 01/15/2017] [Accepted: 01/20/2017] [Indexed: 01/02/2023]
Abstract
Mitochondria are key cellular power plants essential for neuronal growth, survival, function, and regeneration after injury. Given their unique morphological features, neurons face exceptional challenges in maintaining energy homeostasis at distal synapses and growth cones where energy is in high demand. Efficient regulation of mitochondrial trafficking and anchoring is critical for neurons to meet altered energy requirements. Mitochondrial dysfunction and impaired transport have been implicated in several major neurological disorders. Thus, research into energy-mediated regulation of mitochondrial recruitment and redistribution is an important emerging frontier. In this review, I discuss new insights into the mechanisms regulating mitochondrial trafficking and anchoring, and provide an updated overview of how mitochondrial motility maintains energy homeostasis in axons, thus contributing to neuronal growth, regeneration, and synaptic function.
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Affiliation(s)
- Zu-Hang Sheng
- Synaptic Function Section, The Porter Neuroscience Research Center, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Room 2B-215, 35 Convent Drive, Bethesda, MD 20892-3706, USA.
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120
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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.
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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
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121
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Inman DM, Harun-Or-Rashid M. Metabolic Vulnerability in the Neurodegenerative Disease Glaucoma. Front Neurosci 2017; 11:146. [PMID: 28424571 PMCID: PMC5371671 DOI: 10.3389/fnins.2017.00146] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/08/2017] [Indexed: 12/14/2022] Open
Abstract
Axons can be several orders of magnitude longer than neural somas, presenting logistical difficulties in cargo trafficking and structural maintenance. Keeping the axon compartment well supplied with energy also presents a considerable challenge; even seemingly subtle modifications of metabolism can result in functional deficits and degeneration. Axons require a great deal of energy, up to 70% of all energy used by a neuron, just to maintain the resting membrane potential. Axonal energy, in the form of ATP, is generated primarily through oxidative phosphorylation in the mitochondria. In addition, glial cells contribute metabolic intermediates to axons at moments of high activity or according to need. Recent evidence suggests energy disruption is an early contributor to pathology in a wide variety of neurodegenerative disorders characterized by axonopathy. However, the degree to which the energy disruption is intrinsic to the axon vs. associated glia is not clear. This paper will review the role of energy availability and utilization in axon degeneration in glaucoma, a chronic axonopathy of the retinal projection.
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Affiliation(s)
- Denise M Inman
- Department of Pharmaceutical Sciences, Northeast Ohio Medical UniversityRootstown, OH, USA
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