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Wood EH, Kreymerman A, Kowal T, Buickians D, Sun Y, Muscat S, Mercola M, Moshfeghi DM, Goldberg JL. Cellular and subcellular optogenetic approaches towards neuroprotection and vision restoration. Prog Retin Eye Res 2023; 96:101153. [PMID: 36503723 PMCID: PMC10247900 DOI: 10.1016/j.preteyeres.2022.101153] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/27/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022]
Abstract
Optogenetics is defined as the combination of genetic and optical methods to induce or inhibit well-defined events in isolated cells, tissues, or animals. While optogenetics within ophthalmology has been primarily applied towards treating inherited retinal disease, there are a myriad of other applications that hold great promise for a variety of eye diseases including cellular regeneration, modulation of mitochondria and metabolism, regulation of intraocular pressure, and pain control. Supported by primary data from the authors' work with in vitro and in vivo applications, we introduce a novel approach to metabolic regulation, Opsins to Restore Cellular ATP (ORCA). We review the fundamental constructs for ophthalmic optogenetics, present current therapeutic approaches and clinical trials, and discuss the future of subcellular and signaling pathway applications for neuroprotection and vision restoration.
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Affiliation(s)
- Edward H Wood
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Alexander Kreymerman
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA; Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Tia Kowal
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - David Buickians
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Yang Sun
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Stephanie Muscat
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Mark Mercola
- Stanford Cardiovascular Institute, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Darius M Moshfeghi
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Jeffrey L Goldberg
- Spencer Center for Vision Research, Byers Eye Institute, Department of Ophthalmology, Stanford University School of Medicine, Palo Alto, CA, USA.
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2
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Cheng L, Cai B, Lu D, Zeng H. The role of mitochondrial energy metabolism in neuroprotection and axonal regeneration after spinal cord injury. Mitochondrion 2023; 69:57-63. [PMID: 36740158 DOI: 10.1016/j.mito.2023.01.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 01/12/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023]
Abstract
Mitochondrial dysfunction occurs in the early stage of axonal degeneration after spinal cord injury and involves oxidative stress, energy deficiency, imbalance of mitochondrial dynamics, etc., which play a key role in axonal degeneration and regeneration under physiological and pathological conditions. Failure of axonal regeneration can lead to long-term structural and functional damage. Several recent studies have shown that improved mitochondrial energy metabolism provides conditions for axonal regeneration and central nervous system repair. Here, we describe the role of mitochondrial energy metabolism in neuroprotection and axonal regeneration after spinal cord injury and review recent advances in targeted mitochondrial therapy.
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Affiliation(s)
- Li Cheng
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Bin Cai
- Department of Rehabilitation Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Dezhi Lu
- School of Medicine, Shanghai University, Shanghai, China
| | - Hong Zeng
- Department of Rehabilitation Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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3
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Beckers A, Masin L, Dyck A, Bergmans S, Vanhunsel S, Zhang A, Verreet T, Poulain F, Farrow K, Moons L. Optic nerve injury-induced regeneration in the adult zebrafish is accompanied by spatiotemporal changes in mitochondrial dynamics. Neural Regen Res 2023; 18:219-225. [PMID: 35799546 PMCID: PMC9241429 DOI: 10.4103/1673-5374.344837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Axonal regeneration in the central nervous system is an energy-intensive process. In contrast to mammals, adult zebrafish can functionally recover from neuronal injury. This raises the question of how zebrafish can cope with this high energy demand. We previously showed that in adult zebrafish, subjected to an optic nerve crush, an antagonistic axon-dendrite interplay exists wherein the retraction of retinal ganglion cell dendrites is a prerequisite for effective axonal repair. We postulate a ‘dendrites for regeneration’ paradigm that might be linked to intraneuronal mitochondrial reshuffling, as ganglion cells likely have insufficient resources to maintain dendrites and restore axons simultaneously. Here, we characterized both mitochondrial distribution and mitochondrial dynamics within the different ganglion cell compartments (dendrites, somas, and axons) during the regenerative process. Optic nerve crush resulted in a reduction of mitochondria in the dendrites during dendritic retraction, whereafter enlarged mitochondria appeared in the optic nerve/tract during axonal regrowth. Upon dendritic regrowth in the retina, mitochondrial density inside the retinal dendrites returned to baseline levels. Moreover, a transient increase in mitochondrial fission and biogenesis was observed in retinal ganglion cell somas after optic nerve damage. Taken together, these findings suggest that during optic nerve injury-induced regeneration, mitochondria shift from the dendrites to the axons and back again and that temporary changes in mitochondrial dynamics support axonal and dendritic regrowth after optic nerve crush.
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Unraveling Pathophysiological Link Between Mitophagy Pathway and Vascular Dementia. ARCHIVES OF NEUROSCIENCE 2022. [DOI: 10.5812/ans-124588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Context: Vascular dementia (VaD) is the second most common type of dementia after Alzheimer’s disease worldwide. Vascular dementia is a neurodegenerative disorder characterized by gradual cognitive impairment. Ischemic and hemorrhagic strokes result in VaD, markedly distributing cerebral blood flow and decreasing patients’ cognitive and memory performance. Due to their high energy demands, neurons are more sensitive to cellular architecture changes and exposed to mitochondrial stress than other cell types. Mitochondrial dysfunction and selective autophagy of mitochondria, known as mitophagy, are associated with VaD. This review aims to elucidate the association between mitophagy and VaD. Evidence Acquisition: This review was conducted independently by at least two researchers dominant in various VaD studies. We searched databases including Elsevier, Google Scholar, and PubMed using the terms ‘vascular dementia’, ‘vascular cognitive impairment’, and ‘mitophagy’. We evaluated 70 articles on the relationship between VaD and mitophagy and interpreted the results. Adobe Photoshop 2022 was used for drawing figures by researchers. Results: The autophagy process plays a protective role in experimental VaD models via preserving vascular integrity and the structure of the blood-brain barrier, upregulating occludin and claudin protein expressions, reducing oxidative stress, and decreasing cognitive dysfunction. Some studies claim that autophagy could have adverse effects in a time-dependent manner against neuronal injury. Prolonged autophagy and overexpressed autophagic proteins induce ischemic injury and cause neuronal cells to undergo apoptotic cell death. Conclusions: Although there are limited studies on the activation of mitophagy-related pathways in VaD, and the definitive role of mitophagy in neuronal healing is unclear, further research is needed to elucidate mitophagy pathways in neurons.
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Ward A, Jessop F, Faris R, Shoup D, Bosio CM, Peterson KE, Priola SA. Lack of the immune adaptor molecule SARM1 accelerates disease in prion infected mice and is associated with increased mitochondrial respiration and decreased expression of NRF2. PLoS One 2022; 17:e0267720. [PMID: 35507602 PMCID: PMC9067904 DOI: 10.1371/journal.pone.0267720] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 04/13/2022] [Indexed: 11/18/2022] Open
Abstract
Prion diseases are a group of fatal, transmissible neurodegenerative diseases of mammals. In the brain, axonal loss and neuronal death are prominent in prion infection, but the mechanisms remain poorly understood. Sterile alpha and heat/Armadillo motif 1 (SARM1) is a protein expressed in neurons of the brain that plays a critical role in axonal degeneration. Following damage to axons, it acquires an NADase activity that helps to regulate mitochondrial health by breaking down NAD+, a molecule critical for mitochondrial respiration. SARM1 has been proposed to have a protective effect in prion disease, and we hypothesized that it its role in regulating mitochondrial energetics may be involved. We therefore analyzed mitochondrial respiration in SARM1 knockout mice (SARM1KO) and wild-type mice inoculated either with prions or normal brain homogenate. Pathologically, disease was similar in both strains of mice, suggesting that SARM1 mediated axonal degradation is not the sole mechanism of axonal loss during prion disease. However, mitochondrial respiration was significantly increased and disease incubation time accelerated in prion infected SARM1KO mice when compared to wild-type mice. Increased levels of mitochondrial complexes II and IV and decreased levels of NRF2, a potent regulator of reactive oxygen species, were also apparent in the brains of SARM1KO mice when compared to wild-type mice. Our data suggest that SARM1 slows prion disease progression, likely by regulating mitochondrial respiration, which may help to mitigate oxidative stress via NRF2.
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Affiliation(s)
- Anne Ward
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
| | - Forrest Jessop
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
| | - Robert Faris
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Daniel Shoup
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
| | - Catharine M. Bosio
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
| | - Karin E. Peterson
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
| | - Suzette A. Priola
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, Hamilton, Montana, United States of America
- * E-mail:
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Slater PG, Domínguez-Romero ME, Villarreal M, Eisner V, Larraín J. Mitochondrial function in spinal cord injury and regeneration. Cell Mol Life Sci 2022; 79:239. [PMID: 35416520 PMCID: PMC11072423 DOI: 10.1007/s00018-022-04261-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 12/21/2022]
Abstract
Many people around the world suffer from some form of paralysis caused by spinal cord injury (SCI), which has an impact on quality and life expectancy. The spinal cord is part of the central nervous system (CNS), which in mammals is unable to regenerate, and to date, there is a lack of full functional recovery therapies for SCI. These injuries start with a rapid and mechanical insult, followed by a secondary phase leading progressively to greater damage. This secondary phase can be potentially modifiable through targeted therapies. The growing literature, derived from mammalian and regenerative model studies, supports a leading role for mitochondria in every cellular response after SCI: mitochondrial dysfunction is the common event of different triggers leading to cell death, cellular metabolism regulates the immune response, mitochondrial number and localization correlate with axon regenerative capacity, while mitochondrial abundance and substrate utilization regulate neural stem progenitor cells self-renewal and differentiation. Herein, we present a comprehensive review of the cellular responses during the secondary phase of SCI, the mitochondrial contribution to each of them, as well as evidence of mitochondrial involvement in spinal cord regeneration, suggesting that a more in-depth study of mitochondrial function and regulation is needed to identify potential targets for SCI therapeutic intervention.
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Affiliation(s)
- Paula G Slater
- Center for Aging and Regeneration, Departamento de Biología Celular Y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150, Santiago, Chile.
| | - Miguel E Domínguez-Romero
- Center for Aging and Regeneration, Departamento de Biología Celular Y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150, Santiago, Chile
| | - Maximiliano Villarreal
- Center for Aging and Regeneration, Departamento de Biología Celular Y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150, Santiago, Chile
| | - Verónica Eisner
- Center for Aging and Regeneration, Departamento de Biología Celular Y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150, Santiago, Chile
- Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150, Santiago, Chile
| | - Juan Larraín
- Center for Aging and Regeneration, Departamento de Biología Celular Y Molecular, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Alameda 340, 8331150, Santiago, Chile
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7
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Meunier I, Bocquet B, Defoort-Dhellemmes S, Smirnov V, Arndt C, Picot MC, Dollfus H, Charif M, Audo I, Huguet H, Zanlonghi X, Lenaers G. Characterization of SSBP1-related optic atrophy and foveopathy. Sci Rep 2021; 11:18703. [PMID: 34548540 PMCID: PMC8455542 DOI: 10.1038/s41598-021-98150-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 09/03/2021] [Indexed: 11/17/2022] Open
Abstract
Dominant optic atrophy (DOA) is genetically heterogeneous and most commonly caused by mutations in OPA1. To distinguish between the classical OPA1-related and the recently identified SSBP1-related DOAs, the retina and fovea of 27 patients carrying the SSBP1 p.Arg38Gln variant were scrutinized using 20° × 20° macular cube and 30° and 55° field fundus autofluorescence photographs. Age of onset, visual acuity, retinal nerve fiber layer and macular thicknesses were recorded. Three SSBP1-patients were asymptomatic, 10 had isolated DOA, and 12 had a combined DOA plus foveopathy. The foveopathy, with a tiny defect of the ellipsoid and interdigitation lines, was similar in all patients, independent of age. There were no significant statistical differences in terms of visual acuity and SD-OCT measurements between patients with isolated DOA (mean visual acuity in decimals: 0.54 ± 0.41) and those with combined foveopathy (0.50 ± 0.23). Two patients over 50 years of age developed a progressive rod-cone dystrophy, leading to severe visual impairment. SSBP1-related DOA shares similarities with OPA1-related DOA with an incomplete penetrance and an early childhood visual impairment. Nevertheless, the presence of a congenital foveopathy with no impact on visual acuity is a major criterion to distinguish SSBP1 cases and orient the appropriate genetic analysis.
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Affiliation(s)
- Isabelle Meunier
- National reference centre for inherited sensory diseases, University Hospital of Montpellier, University of Montpellier, Montpellier, France. .,Sensgene Care Network, Strasbourg, France. .,Institute for Neurosciences of Montpellier, Inserm, University of Montpellier, Montpellier, France.
| | - Béatrice Bocquet
- National reference centre for inherited sensory diseases, University Hospital of Montpellier, University of Montpellier, Montpellier, France.,Sensgene Care Network, Strasbourg, France.,Institute for Neurosciences of Montpellier, Inserm, University of Montpellier, Montpellier, France
| | - Sabine Defoort-Dhellemmes
- Sensgene Care Network, Strasbourg, France.,Department of Neuro-Ophthalmology and Electrophysiology, Robert Salengro Hospital, Lille, France
| | - Vasily Smirnov
- Sensgene Care Network, Strasbourg, France.,Department of Neuro-Ophthalmology and Electrophysiology, Robert Salengro Hospital, Lille, France
| | - Carl Arndt
- Department of Ophthalmology, University Hospital of Reims, Reims, France
| | - Marie Christine Picot
- Clinical Investigation Center (CIC) and Clinical Research and Epidemiology Unit (URCE), Montpellier, France
| | - Hélène Dollfus
- Sensgene Care Network, Strasbourg, France.,Department of Ophthalmology, National Center for Rare Disorders in Ophthalmic Genetics CARGO, Strasbourg Hospital, Strasbourg, France
| | - Majida Charif
- Genetics and Immuno-Cell Therapy Team, Mohammed First University, Oujda, Morocco
| | - Isabelle Audo
- Sensgene Care Network, Strasbourg, France.,CNRS, INSERM, Institut de la Vision, Sorbonne Université, Paris, France.,DHU Sight Restore, INSERM-DHOS CIC1423, CHNO des Quinze-Vingts, Paris, France
| | - Hélèna Huguet
- Clinical Investigation Center (CIC) and Clinical Research and Epidemiology Unit (URCE), Montpellier, France
| | - Xavier Zanlonghi
- Sensgene Care Network, Strasbourg, France.,Clinic Jules Verne, Nantes, France.,Department of Ophthalmology, University Hospital of Rennes, Rennes, France
| | - Guy Lenaers
- UMR CNRS 6015 - INSERM U1083, University of Angers MitoLab Team, University Hospital of Angers, Angers, France
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Jimenez-Tellez N, Iqbal F, Pehar M, Casas-Ortiz A, Rice T, Syed NI. Dexmedetomidine does not compromise neuronal viability, synaptic connectivity, learning and memory in a rodent model. Sci Rep 2021; 11:16153. [PMID: 34373548 PMCID: PMC8352930 DOI: 10.1038/s41598-021-95635-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/21/2021] [Indexed: 02/08/2023] Open
Abstract
Recent animal studies have drawn concerns regarding most commonly used anesthetics and their long-term cytotoxic effects, specifically on the nervous tissue. It is therefore imperative that the search continues for agents that are non-toxic at both the cellular and behavioural level. One such agent appears to be dexmedetomidine (DEX) which has not only been found to be less neurotoxic but has also been shown to protect neurons from cytotoxicity induced by other anesthetic agents. However, DEX's effects on the growth and synaptic connectivity at the individual neuronal level, and the underlying mechanisms have not yet been fully resolved. Here, we tested DEX for its impact on neuronal growth, synapse formation (in vitro) and learning and memory in a rodent model. Rat cortical neurons were exposed to a range of clinically relevant DEX concentrations (0.05-10 µM) and cellular viability, neurite outgrowth, synaptic assembly and mitochondrial morphology were assessed. We discovered that DEX did not affect neuronal viability when used below 10 µM, whereas significant cell death was noted at higher concentrations. Interestingly, in the presence of DEX, neurons exhibited more neurite branching, albeit with no differences in corresponding synaptic puncta formation. When rat pups were injected subcutaneously with DEX 25 µg/kg on postnatal day 7 and again on postnatal day 8, we discovered that this agent did not affect hippocampal-dependent memory in freely behaving animals. Our data demonstrates, for the first time, the non-neurotoxic nature of DEX both in vitro and in vivo in an animal model providing support for its utility as a safer anesthetic agent. Moreover, this study provides the first direct evidence that although DEX is growth permissive, causes mitochondrial fusion and reduces oxygen reactive species production, it does not affect the total number of synaptic connections between the cortical neurons in vitro.
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Affiliation(s)
- Nerea Jimenez-Tellez
- grid.22072.350000 0004 1936 7697Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada ,grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Calgary, Canada ,grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, Canada
| | - Fahad Iqbal
- grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, Canada
| | - Marcus Pehar
- grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Calgary, Canada ,grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, Canada
| | - Alberto Casas-Ortiz
- grid.22072.350000 0004 1936 7697Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, Canada ,grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, Canada
| | - Tiffany Rice
- grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, Canada ,grid.22072.350000 0004 1936 7697Department of Anesthesiology, Perioperative and Pain Medicine, University of Calgary, Calgary, Canada
| | - Naweed I. Syed
- grid.22072.350000 0004 1936 7697Hotchkiss Brain Institute, Calgary, Canada ,grid.413571.50000 0001 0684 7358Alberta Children’s Hospital Research Institute, Calgary, Canada ,grid.22072.350000 0004 1936 7697Department of Cell Biology and Anatomy, University of Calgary, Calgary, Canada
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Unraveling Axon Guidance during Axotomy and Regeneration. Int J Mol Sci 2021; 22:ijms22158344. [PMID: 34361110 PMCID: PMC8347220 DOI: 10.3390/ijms22158344] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 02/06/2023] Open
Abstract
During neuronal development and regeneration axons extend a cytoskeletal-rich structure known as the growth cone, which detects and integrates signals to reach its final destination. The guidance cues “signals” bind their receptors, activating signaling cascades that result in the regulation of the growth cone cytoskeleton, defining growth cone advance, pausing, turning, or collapse. Even though much is known about guidance cues and their isolated mechanisms during nervous system development, there is still a gap in the understanding of the crosstalk between them, and about what happens after nervous system injuries. After neuronal injuries in mammals, only axons in the peripheral nervous system are able to regenerate, while the ones from the central nervous system fail to do so. Therefore, untangling the guidance cues mechanisms, as well as their behavior and characterization after axotomy and regeneration, are of special interest for understanding and treating neuronal injuries. In this review, we present findings on growth cone guidance and canonical guidance cues mechanisms, followed by a description and comparison of growth cone pathfinding mechanisms after axotomy, in regenerative and non-regenerative animal models.
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10
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The Axonal Glycolytic Pathway Contributes to Sensory Axon Extension and Growth Cone Dynamics. J Neurosci 2021; 41:6637-6651. [PMID: 34252036 DOI: 10.1523/jneurosci.0321-21.2021] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/19/2021] [Accepted: 06/12/2021] [Indexed: 01/18/2023] Open
Abstract
Understanding the bioenergetics of axon extension and maintenance has wide ranging implications for neurodevelopment and disease states. Glycolysis is a pathway consisting of 10 enzymes and separated into preparatory and payoff phases, the latter producing ATP. Using embryonic chicken sensory neurons, we report that glycolytic enzymes are found through the axon and the growth cone. Pharmacological inhibition of glycolysis in the presence of NGF impairs axon extension and growth cone dynamics within minutes without affecting axon maintenance. Experiments using microfluidic chambers show that the effect of inhibiting glycolysis on axon extension is local along distal axons and can be reversed by promoting mitochondrial respiration. Knockdown of GAPDH simplifies growth cone morphology and is rescued by shRNA-resistant GAPDH expression. Rescue of GAPDH using KillerRed fused to GAPDH followed by localized chromophore-assisted light inactivation of KillerRed-GAPDH in distal axons halts growth cone dynamics. Considering filament polymerization requires ATP, inhibition of glycolysis results in a paradoxical increase in axonal actin filament levels. The effect on actin filaments is because of enzymes before GAPDH, the first enzyme in the payoff phase. In the absence of NGF, inhibition of glycolysis along distal axons results in axon degeneration independent of cell death. These data indicate that the glycolytic pathway is operative in distal axons and contributes to the rate of axon extension and growth cone dynamics in the presence of NGF and that, in the absence of NGF, the axonal glycolytic pathway is required for axon maintenance.SIGNIFICANCE STATEMENT Elucidation of the sources of ATP required for axon extension and maintenance has implications for understanding the mechanism of neuronal development and diseases of the nervous system. While recent work has emphasized the importance of mitochondrial oxidative phosphorylation, the role of the glycolytic pathway in axon morphogenesis and maintenance remains minimally understood. The data reveal that the glycolytic pathway is required for normal sensory axon extension in the presence of NGF, while in the absence of NGF the glycolytic pathway is required for axon maintenance. The results have implications for the understanding of the bioenergetics of axon morphogenesis and plasticity and indicate that NGF has protective effects on sensory axon maintenance in hypoglycemic states.
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11
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Kedra J, Lin S, Pacheco A, Gallo G, Smith GM. Axotomy Induces Drp1-Dependent Fragmentation of Axonal Mitochondria. Front Mol Neurosci 2021; 14:668670. [PMID: 34149354 PMCID: PMC8209475 DOI: 10.3389/fnmol.2021.668670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/07/2021] [Indexed: 02/02/2023] Open
Abstract
It is well established that CNS axons fail to regenerate, undergo retrograde dieback, and form dystrophic growth cones due to both intrinsic and extrinsic factors. We sought to investigate the role of axonal mitochondria in the axonal response to injury. A viral vector (AAV) containing a mitochondrially targeted fluorescent protein (mitoDsRed) as well as fluorescently tagged LC3 (GFP-LC3), an autophagosomal marker, was injected into the primary motor cortex, to label the corticospinal tract (CST), of adult rats. The axons of the CST were then injured by dorsal column lesion at C4-C5. We found that mitochondria in injured CST axons near the injury site are fragmented and fragmentation of mitochondria persists for 2 weeks before returning to pre-injury lengths. Fragmented mitochondria have consistently been shown to be dysfunctional and detrimental to cellular health. Inhibition of Drp1, the GTPase responsible for mitochondrial fission, using a specific pharmacological inhibitor (mDivi-1) blocked fragmentation. Additionally, it was determined that there is increased mitophagy in CST axons following Spinal cord injury (SCI) based on increased colocalization of mitochondria and LC3. In vitro models revealed that mitochondrial divalent ion uptake is necessary for injury-induced mitochondrial fission, as inhibiting the mitochondrial calcium uniporter (MCU) using RU360 prevented injury-induced fission. This phenomenon was also observed in vivo. These studies indicate that following the injury, both in vivo and in vitro, axonal mitochondria undergo increased fission, which may contribute to the lack of regeneration seen in CNS neurons.
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Affiliation(s)
- Joseph Kedra
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Shen Lin
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Almudena Pacheco
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - Gianluca Gallo
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
| | - George M Smith
- Shriners Hospitals Pediatric Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States.,Department of Neuroscience, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, United States
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12
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Axonal Organelles as Molecular Platforms for Axon Growth and Regeneration after Injury. Int J Mol Sci 2021; 22:ijms22041798. [PMID: 33670312 PMCID: PMC7918155 DOI: 10.3390/ijms22041798] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 02/06/2023] Open
Abstract
Investigating the molecular mechanisms governing developmental axon growth has been a useful approach for identifying new strategies for boosting axon regeneration after injury, with the goal of treating debilitating conditions such as spinal cord injury and vision loss. The picture emerging is that various axonal organelles are important centers for organizing the molecular mechanisms and machinery required for growth cone development and axon extension, and these have recently been targeted to stimulate robust regeneration in the injured adult central nervous system (CNS). This review summarizes recent literature highlighting a central role for organelles such as recycling endosomes, the endoplasmic reticulum, mitochondria, lysosomes, autophagosomes and the proteasome in developmental axon growth, and describes how these organelles can be targeted to promote axon regeneration after injury to the adult CNS. This review also examines the connections between these organelles in developing and regenerating axons, and finally discusses the molecular mechanisms within the axon that are required for successful axon growth.
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13
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Doxaki C, Palikaras K. Neuronal Mitophagy: Friend or Foe? Front Cell Dev Biol 2021; 8:611938. [PMID: 33537304 PMCID: PMC7848077 DOI: 10.3389/fcell.2020.611938] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/22/2020] [Indexed: 12/23/2022] Open
Abstract
Maintenance of neuronal homeostasis is a challenging task, due to unique cellular organization and bioenergetic demands of post-mitotic neurons. It is increasingly appreciated that impairment of mitochondrial homeostasis represents an early sign of neuronal dysfunction that is common in both age-related neurodegenerative as well as in neurodevelopmental disorders. Mitochondrial selective autophagy, known as mitophagy, regulates mitochondrial number ensuring cellular adaptation in response to several intracellular and environmental stimuli. Mounting evidence underlines that deregulation of mitophagy levels has an instructive role in the process of neurodegeneration. Although mitophagy induction mediates the elimination of damaged mitochondria and confers neuroprotection, uncontrolled runaway mitophagy could reduce mitochondrial content overstressing the remaining organelles and eventually triggering neuronal cell death. Unveiling the molecular mechanisms of neuronal mitophagy and its intricate role in neuronal survival and cell death, will assist in the development of novel mitophagy modulators to promote cellular and organismal homeostasis in health and disease.
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Affiliation(s)
| | - Konstantinos Palikaras
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Crete, Greece
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14
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Sun S, Erchova I, Sengpiel F, Votruba M. Opa1 Deficiency Leads to Diminished Mitochondrial Bioenergetics With Compensatory Increased Mitochondrial Motility. Invest Ophthalmol Vis Sci 2021; 61:42. [PMID: 32561926 PMCID: PMC7415319 DOI: 10.1167/iovs.61.6.42] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose Retinal ganglion cells (RGCs) are susceptible to mitochondrial deficits and also the major cell type affected in patients with mutations in the OPA1 gene in autosomal dominant optic atrophy (ADOA). Here, we characterized mitochondria in RGCs in vitro from a heterozygous B6; C3-Opa1Q285STOP (Opa1+/−) mouse model to investigate mitochondrial changes underlying the pathology in ADOA. Methods Mouse RGCs were purified from wild-type and Opa1+/− mouse retina by two-step immunopanning. The mitochondria in neurites of RGCs were labeled with MitoTracker Red for structure and motility measurement by time-lapse imaging. Mitochondrial bioenergetics were determined by the real-time measurement of oxygen consumption rate using a Seahorse XFe 96 Extracellular Flux Analyzer. Results We observed a significant decrease in mitochondrial length in Opa1+/− RGCs with a remarkably higher proportion and density of motile mitochondria along the neurites. We also observed an increased transport velocity with a higher number of contacts between mitochondria in Opa1+/− RGC neurites. The oxygen consumption assays showed a severe impairment in basal respiration, Adenosine triphosphate-linked (ATP-linked) oxygen consumption, as well as reserve respiratory capacity, in RGCs from Opa1+/− mouse retina. Conclusions Opa1 deficiency leads to significant fragmentation of mitochondrial morphology, activation of mitochondrial motility and impaired respiratory function in RGCs from the B6; C3-Opa1Q285STOP mouse model. This highlights the significant alterations in the intricate interplay between mitochondrial morphology, motility, and energy production in RGCs with Opa1 deficiency long before the onset of clinical symptoms of the pathology.
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15
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Lee S, Kim S, Kang HY, Lim HR, Kwon Y, Jo M, Jeon YM, Kim SR, Kim K, Ha CM, Lee S, Kim HJ. The overexpression of TDP-43 in astrocytes causes neurodegeneration via a PTP1B-mediated inflammatory response. J Neuroinflammation 2020; 17:299. [PMID: 33054766 PMCID: PMC7556969 DOI: 10.1186/s12974-020-01963-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 09/23/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Cytoplasmic inclusions of transactive response DNA binding protein of 43 kDa (TDP-43) in neurons and astrocytes are a feature of some neurodegenerative diseases, such as frontotemporal lobar degeneration with TDP-43 (FTLD-TDP) and amyotrophic lateral sclerosis (ALS). However, the role of TDP-43 in astrocyte pathology remains largely unknown. METHODS To investigate whether TDP-43 overexpression in primary astrocytes could induce inflammation, we transfected primary astrocytes with plasmids encoding Gfp or TDP-43-Gfp. The inflammatory response and upregulation of PTP1B in transfected cells were examined using quantitative RT-PCR and immunoblot analysis. Neurotoxicity was analysed in a transwell coculture system of primary cortical neurons with astrocytes and cultured neurons treated with astrocyte-conditioned medium (ACM). We also examined the lifespan, performed climbing assays and analysed immunohistochemical data in pan-glial TDP-43-expressing flies in the presence or absence of a Ptp61f RNAi transgene. RESULTS PTP1B inhibition suppressed TDP-43-induced secretion of inflammatory cytokines (interleukin 1 beta (IL-1β), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α)) in primary astrocytes. Using a neuron-astrocyte coculture system and astrocyte-conditioned media treatment, we demonstrated that PTP1B inhibition attenuated neuronal death and mitochondrial dysfunction caused by overexpression of TDP-43 in astrocytes. In addition, neuromuscular junction (NMJ) defects, a shortened lifespan, inflammation and climbing defects caused by pan-glial overexpression of TDP-43 were significantly rescued by downregulation of ptp61f (the Drosophila homologue of PTP1B) in flies. CONCLUSIONS These results indicate that PTP1B inhibition mitigates the neuronal toxicity caused by TDP-43-induced inflammation in mammalian astrocytes and Drosophila glial cells.
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Affiliation(s)
- Shinrye Lee
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
| | - Seyeon Kim
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
- Department of Brain & Cognitive Sciences, DGIST, Daegu, 42988, South Korea
| | - Ha-Young Kang
- Gwangju Center, Korea Basic Science Institute (KBSI), Gwangju, 61886, South Korea
| | - Hye Ryeong Lim
- Research Division and Brain Research Core Facilities, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
| | - Younghwi Kwon
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
- Department of Brain & Cognitive Sciences, DGIST, Daegu, 42988, South Korea
| | - Myungjin Jo
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
| | - Yu-Mi Jeon
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
| | - Sang Ryong Kim
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Institute of Life Science & Biotechnology, Kyungpook National University, Daegu, 41566, South Korea
- Brain Science and Engineering Institute, Kyungpook National University, Daegu, 41944, South Korea
| | - Kiyoung Kim
- Department of Medical Biotechnology, Soonchunhyang University, Asan, 31538, South Korea
| | - Chang Man Ha
- Research Division and Brain Research Core Facilities, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea
| | - Seongsoo Lee
- Gwangju Center, Korea Basic Science Institute (KBSI), Gwangju, 61886, South Korea.
| | - Hyung-Jun Kim
- Dementia Research Group, Korea Brain Research Institute (KBRI), Daegu, 41062, South Korea.
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16
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Gallo G. The bioenergetics of neuronal morphogenesis and regeneration: Frontiers beyond the mitochondrion. Dev Neurobiol 2020; 80:263-276. [PMID: 32750228 DOI: 10.1002/dneu.22776] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 12/27/2022]
Abstract
The formation of axons and dendrites during development, and their regeneration following injury, are energy intensive processes. The underlying assembly and dynamics of the cytoskeleton, axonal transport mechanisms, and extensive signaling networks all rely on ATP and GTP consumption. Cellular ATP is generated through oxidative phosphorylation (OxP) in mitochondria, glycolysis and "regenerative" kinase systems. Recent investigations have focused on the role of the mitochondrion in axonal development and regeneration emphasizing the importance of this organelle and OxP in axon development and regeneration. In contrast, the understanding of alternative sources of ATP in neuronal morphogenesis and regeneration remains largely unexplored. This review focuses on the current state of the field of neuronal bioenergetics underlying morphogenesis and regeneration and considers the literature on the bioenergetics of non-neuronal cell motility to emphasize the potential contributions of non-mitochondrial energy sources.
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Affiliation(s)
- Gianluca Gallo
- Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Shriners Hospitals Pediatric Research Center, Temple University, Philadelphia, PA, USA
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17
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Rexius-Hall ML, Khalil NN, Andres AM, McCain ML. Mitochondrial division inhibitor 1 (mdivi-1) increases oxidative capacity and contractile stress generated by engineered skeletal muscle. FASEB J 2020; 34:11562-11576. [PMID: 32652761 DOI: 10.1096/fj.201901039rr] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Revised: 06/03/2020] [Accepted: 06/08/2020] [Indexed: 12/16/2022]
Abstract
In skeletal muscle fibers, mitochondria are densely packed adjacent to myofibrils because adenosine triphosphate (ATP) is needed to fuel sarcomere shortening. However, despite this close physical and biochemical relationship, the effects of mitochondrial dynamics on skeletal muscle contractility are poorly understood. In this study, we analyzed the effects of Mitochondrial Division Inhibitor 1 (mdivi-1), an inhibitor of mitochondrial fission, on the structure and function of both mitochondria and myofibrils in skeletal muscle tissues engineered on micromolded gelatin hydrogels. Treatment with mdivi-1 did not alter myotube morphology, but did increase the mitochondrial turbidity and oxidative capacity, consistent with reduced mitochondrial fission. Mdivi-1 also significantly increased basal, twitch, and tetanus stresses, as measured using the Muscular Thin Film (MTF) assay. Finally, mdivi-1 increased sarcomere length, potentially due to mdivi-1-induced changes in mitochondrial volume and compression of myofibrils. Together, these results suggest that mdivi-1 increases contractile stress generation, which may be caused by an increase in maximal respiration and/or sarcomere length due to increased volume of individual mitochondria. These data reinforce that mitochondria have both biochemical and biomechanical roles in skeletal muscle and that mitochondrial dynamics can be manipulated to alter muscle contractility.
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Affiliation(s)
- Megan L Rexius-Hall
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Natalie N Khalil
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA
| | - Allen M Andres
- Smidt Heart Institute and Barbra Streisand Women's Heart Center, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Megan L McCain
- Laboratory for Living Systems Engineering, Department of Biomedical Engineering, USC Viterbi School of Engineering, University of Southern California, Los Angeles, CA, USA.,Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine of USC, University of Southern California, Los Angeles, CA, USA
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18
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Targeted Krüppel-Like Factor 4 Gene Knock-Out in Retinal Ganglion Cells Improves Visual Function in Multiple Sclerosis Mouse Model. eNeuro 2020; 7:ENEURO.0320-19.2020. [PMID: 32165410 PMCID: PMC7139550 DOI: 10.1523/eneuro.0320-19.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 02/12/2020] [Accepted: 02/20/2020] [Indexed: 12/26/2022] Open
Abstract
Axonal demyelination injury and neuronal degeneration are the primary causes of visual disability in multiple sclerosis (MS)-linked optic neuritis patients. Immunomodulatory therapies targeting inflammation have failed to avert the disease progression and no therapies exist to prevent the neuronal deficits seen in MS to date. Neuroprotective strategies targeting oligodendrocytes and astroglia have shown limited success due to a lack of axonal regeneration from injured neurons. In this study, we used the chronic experimental autoimmune encephalomyelitis (EAE) mouse model of MS to investigate the axonal regenerative approach to improve the neuronal function. Our approach focused on targeted knock-out (KO) of the developmentally regulated axon growth inhibitory Krüppel-like factor 4 (Klf4) gene in retinal ganglion cells (RGCs) of Klf4fl/flmice by intravitreal delivery of AAV2-Cre-ires-EGFP recombinant virus (1) at the time of EAE sensitization and (2) after the onset of optic neuritis-mediated visual defects in the mice. Klf4 gene KO performed simultaneous with EAE sensitization prevented the visual loss as assessed by pattern electroretinograms (PERGs) in the mice and protected the RGCs from EAE-mediated death. More importantly, however, Klf4 gene KO after the onset of optic neuritis also resulted in RGC neuroprotection with additional restoration of their function, thereby improving the visual function outcomes in the EAE model. This study establishes the efficacy of Klf4 targeted knock-down in EAE even after the onset of disease symptoms, and thus should be further explored as a potential treatment strategy for MS/optic neuritis patients.
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19
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Vohra R, Kolko M. Lactate: More Than Merely a Metabolic Waste Product in the Inner Retina. Mol Neurobiol 2020; 57:2021-2037. [PMID: 31916030 DOI: 10.1007/s12035-019-01863-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/22/2019] [Indexed: 02/07/2023]
Abstract
The retina is an extension of the central nervous system and has been considered to be a simplified, more tractable and accessible version of the brain for a variety of neuroscience investigations. The optic nerve displays changes in response to underlying neurodegenerative diseases, such as stroke, multiple sclerosis, and Alzheimer's disease, as well as inner retinal neurodegenerative disease, e.g., glaucoma. Neurodegeneration has increasingly been linked to dysfunctional energy metabolism or conditions in which the energy supply does not meet the demand. Likewise, increasing lactate levels have been correlated with conditions consisting of unbalanced energy supply and demand, such as ischemia-associated diseases or excessive exercise. Lactate has thus been acknowledged as a metabolic waste product in organs with high energy metabolism. However, in the past decade, numerous beneficial roles of lactate have been revealed in the central nervous system. In this context, lactate has been identified as a valuable energy substrate, protecting against glutamate excitotoxicity and ischemia, as well as having signaling properties which regulate cellular functions. The present review aims to summarize and discuss protective roles of lactate in various model systems (in vitro, ex vivo, and in vivo) reflecting the inner retina focusing on lactate metabolism and signaling in inner retinal homeostasis and disease.
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Affiliation(s)
- Rupali Vohra
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.,Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Miriam Kolko
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark. .,Department of Ophthalmology, Rigshospitalet-Glostrup, University of Copenhagen, Glostrup, Denmark.
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20
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Syntaphilin-Mediated Docking of Mitochondria at the Growth Cone Is Dispensable for Axon Elongation In Vivo. eNeuro 2019; 6:ENEURO.0026-19.2019. [PMID: 31481398 PMCID: PMC6751374 DOI: 10.1523/eneuro.0026-19.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Revised: 08/15/2019] [Accepted: 08/22/2019] [Indexed: 11/25/2022] Open
Abstract
Mitochondria are abundantly detected at the growth cone, the dynamic distal tip of developing axons that directs growth and guidance. It is, however, poorly understood how mitochondrial dynamics relate to growth cone behavior in vivo, and which mechanisms are responsible for anchoring mitochondria at the growth cone during axon pathfinding. Here, we show that in retinal axons elongating along the optic tract in zebrafish, mitochondria accumulate in the central area of the growth cone and are occasionally observed in filopodia extending from the growth cone periphery. Mitochondrial behavior at the growth cone in vivo is dynamic, with mitochondrial positioning and anterograde transport strongly correlating with growth cone behavior and axon outgrowth. Using novel zebrafish mutant lines that lack the mitochondrial anchoring proteins Syntaphilin a and b, we further show that Syntaphilins contribute to mitochondrial immobilization at the growth cone. Syntaphilins are, however, not required for proper growth cone morphology and axon growth in vivo, indicating that Syntaphilin-mediated anchoring of mitochondria at the growth cone plays only a minor role in elongating axons.
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21
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Effects of abnormal expression of fusion and fission genes on the morphology and function of lung macrophage mitochondria in SiO2-induced silicosis fibrosis in rats in vivo. Toxicol Lett 2019; 312:181-187. [DOI: 10.1016/j.toxlet.2019.04.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 04/11/2019] [Accepted: 04/24/2019] [Indexed: 12/19/2022]
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22
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Dexamethasone Provides Effective Immunosuppression for Improved Survival of Retinal Organoids after Epiretinal Transplantation. Stem Cells Int 2019; 2019:7148032. [PMID: 31428159 PMCID: PMC6683795 DOI: 10.1155/2019/7148032] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/31/2019] [Accepted: 07/02/2019] [Indexed: 12/16/2022] Open
Abstract
We investigated the efficacy of the immunosuppressants rapamycin (RAP) and dexamethasone (DEX) in improving the survival of retinal organoids after epiretinal transplantation. We first compared the immunosuppressive abilities of DEX and RAP in activated microglia in an in vitro setting. Following this, we used immunofluorescence, real-time polymerase chain reaction, and flow cytometry to investigate the effects of DEX and RAP on cells in the retinal organoids. Retinal organoids were then seeded onto poly(lactic-co-glycolic) acid (PLGA) scaffolds and implanted into rhesus monkey eyes (including a healthy individual and three monkeys with chronic ocular hypertension (OHT) induction) and subjected to different post-operative immunosuppressant treatments; 8 weeks after the experiment, histological examinations were carried out to assess the success of the different treatments. Our in vitro experiments indicated that both DEX and RAP treatments were equally effective in suppressing microglial activity. Although both immunosuppressants altered the morphologies of cells in the retinal organoids and caused a slight decrease in the differentiation of cells into retinal ganglion cells, the organoid cells retained their capacity to grow and differentiate into retinal tissues. Our in vivo experiments indicate that the retinal organoid can survive and differentiate into retinal tissues in a healthy rhesus monkey eye without immunosuppressive treatment. However, the survival and differentiation of these organoids in OHT eyes was successful only with the DEX treatment. RAP treatment was ineffective in preventing immunological rejection, and the retinal organoid failed to survive until the end of 8 weeks. DEX is likely a promising immunosuppressant to enhance the survival of epiretinal implants.
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23
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Kreymerman A, Buickians DN, Nahmou MM, Tran T, Galvao J, Wang Y, Sun N, Bazik L, Huynh SK, Cho IJ, Boczek T, Chang KC, Kunzevitzky NJ, Goldberg JL. MTP18 is a Novel Regulator of Mitochondrial Fission in CNS Neuron Development, Axonal Growth, and Injury Responses. Sci Rep 2019; 9:10669. [PMID: 31337818 PMCID: PMC6650498 DOI: 10.1038/s41598-019-46956-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 07/05/2019] [Indexed: 12/17/2022] Open
Abstract
The process of mitochondrial fission-fusion has been implicated in diverse neuronal roles including neuronal survival, axon degeneration, and axon regeneration. However, whether increased fission or fusion is beneficial for neuronal health and/or axonal growth is not entirely clear, and is likely situational and cell type-dependent. In searching for mitochondrial fission-fusion regulating proteins for improving axonal growth within the visual system, we uncover that mitochondrial fission process 1,18 kDa (MTP18/MTFP1), a pro-fission protein within the CNS, is critical to maintaining mitochondrial size and volume under normal and injury conditions, in retinal ganglion cells (RGCs). We demonstrate that MTP18’s expression is regulated by transcription factors involved in axonal growth, Kruppel-like factor (KLF) transcription factors-7 and -9, and that knockdown of MTP18 promotes axon growth. This investigation exposes MTP18’s previously unexplored role in regulating mitochondrial fission, implicates MTP18 as a downstream component of axon regenerative signaling, and ultimately lays the groundwork for investigations on the therapeutic efficacy of MTP18 expression suppression during CNS axon degenerative events.
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Affiliation(s)
- Alexander Kreymerman
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA. .,University of Miami Miller School of Medicine, Miami, FL, 33136, USA.
| | - David N Buickians
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Michael M Nahmou
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Tammy Tran
- University of California, San Diego, CA, 92093, USA
| | - Joana Galvao
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Yan Wang
- University of California, San Diego, CA, 92093, USA
| | - Nicholas Sun
- University of California, San Diego, CA, 92093, USA
| | - Leah Bazik
- University of California, San Diego, CA, 92093, USA
| | - Star K Huynh
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - In-Jae Cho
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Tomasz Boczek
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Kun-Che Chang
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Noelia J Kunzevitzky
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
| | - Jeffrey L Goldberg
- Byers Eye Institute and Spencer Center for Vision Research, Stanford University, Palo Alto, CA, 94303, USA
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24
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Kalinski AL, Kar AN, Craver J, Tosolini AP, Sleigh JN, Lee SJ, Hawthorne A, Brito-Vargas P, Miller-Randolph S, Passino R, Shi L, Wong VSC, Picci C, Smith DS, Willis DE, Havton LA, Schiavo G, Giger RJ, Langley B, Twiss JL. Deacetylation of Miro1 by HDAC6 blocks mitochondrial transport and mediates axon growth inhibition. J Cell Biol 2019; 218:1871-1890. [PMID: 31068376 PMCID: PMC6548128 DOI: 10.1083/jcb.201702187] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 02/15/2018] [Accepted: 04/15/2019] [Indexed: 02/08/2023] Open
Abstract
Inhibition of histone deacetylase 6 (HDAC6) was shown to support axon growth on the nonpermissive substrates myelin-associated glycoprotein (MAG) and chondroitin sulfate proteoglycans (CSPGs). Though HDAC6 deacetylates α-tubulin, we find that another HDAC6 substrate contributes to this axon growth failure. HDAC6 is known to impact transport of mitochondria, and we show that mitochondria accumulate in distal axons after HDAC6 inhibition. Miro and Milton proteins link mitochondria to motor proteins for axon transport. Exposing neurons to MAG and CSPGs decreases acetylation of Miro1 on Lysine 105 (K105) and decreases axonal mitochondrial transport. HDAC6 inhibition increases acetylated Miro1 in axons, and acetyl-mimetic Miro1 K105Q prevents CSPG-dependent decreases in mitochondrial transport and axon growth. MAG- and CSPG-dependent deacetylation of Miro1 requires RhoA/ROCK activation and downstream intracellular Ca2+ increase, and Miro1 K105Q prevents the decrease in axonal mitochondria seen with activated RhoA and elevated Ca2+ These data point to HDAC6-dependent deacetylation of Miro1 as a mediator of axon growth inhibition through decreased mitochondrial transport.
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Affiliation(s)
- Ashley L Kalinski
- Department of Biology, Drexel University, Philadelphia, PA.,Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Amar N Kar
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | - John Craver
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | - Andrew P Tosolini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - James N Sleigh
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK
| | - Seung Joon Lee
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | | | - Paul Brito-Vargas
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | | | - Ryan Passino
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI
| | - Liang Shi
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | | | | | - Deanna S Smith
- Department of Biological Sciences, University of South Carolina, Columbia, SC
| | | | - Leif A Havton
- Departments of Neurology and Neurobiology, University of California, Los Angeles, Los Angeles, CA
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK.,UK Dementia Research Institute, University College London, London, UK.,Discoveries Centre for Regenerative and Precision Medicine, University College London Campus, London, UK
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI
| | | | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC
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25
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Ye X, Qiu Y, Gao Y, Wan D, Zhu H. A Subtle Network Mediating Axon Guidance: Intrinsic Dynamic Structure of Growth Cone, Attractive and Repulsive Molecular Cues, and the Intermediate Role of Signaling Pathways. Neural Plast 2019; 2019:1719829. [PMID: 31097955 PMCID: PMC6487106 DOI: 10.1155/2019/1719829] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/25/2019] [Accepted: 03/06/2019] [Indexed: 01/01/2023] Open
Abstract
A fundamental feature of both early nervous system development and axon regeneration is the guidance of axonal projections to their targets in order to assemble neural circuits that control behavior. In the navigation process where the nerves grow toward their targets, the growth cones, which locate at the tips of axons, sense the environment surrounding them, including varies of attractive or repulsive molecular cues, then make directional decisions to adjust their navigation journey. The turning ability of a growth cone largely depends on its highly dynamic skeleton, where actin filaments and microtubules play a very important role in its motility. In this review, we summarize some possible mechanisms underlying growth cone motility, relevant molecular cues, and signaling pathways in axon guidance of previous studies and discuss some questions regarding directions for further studies.
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Affiliation(s)
- Xiyue Ye
- College of Pharmaceutical Sciences and Traditional Chinese Medicine, Southwest University, Chongqing 400715, China
- Chongqing Engineering Research Center for Pharmacological Evaluation, Chongqing 400715, China
- Engineering Research Center for Chongqing Pharmaceutical Process and Quality Control, Chongqing 400715, China
| | - Yan Qiu
- College of Pharmaceutical Sciences and Traditional Chinese Medicine, Southwest University, Chongqing 400715, China
- Chongqing Engineering Research Center for Pharmacological Evaluation, Chongqing 400715, China
- Engineering Research Center for Chongqing Pharmaceutical Process and Quality Control, Chongqing 400715, China
| | - Yuqing Gao
- College of Pharmaceutical Sciences and Traditional Chinese Medicine, Southwest University, Chongqing 400715, China
- Chongqing Engineering Research Center for Pharmacological Evaluation, Chongqing 400715, China
- Engineering Research Center for Chongqing Pharmaceutical Process and Quality Control, Chongqing 400715, China
| | - Dong Wan
- Department of Emergency, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, China
| | - Huifeng Zhu
- College of Pharmaceutical Sciences and Traditional Chinese Medicine, Southwest University, Chongqing 400715, China
- Chongqing Engineering Research Center for Pharmacological Evaluation, Chongqing 400715, China
- Engineering Research Center for Chongqing Pharmaceutical Process and Quality Control, Chongqing 400715, China
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26
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Aghanoori MR, Smith DR, Shariati-Ievari S, Ajisebutu A, Nguyen A, Desmond F, Jesus CHA, Zhou X, Calcutt NA, Aliani M, Fernyhough P. Insulin-like growth factor-1 activates AMPK to augment mitochondrial function and correct neuronal metabolism in sensory neurons in type 1 diabetes. Mol Metab 2019; 20:149-165. [PMID: 30545741 PMCID: PMC6358538 DOI: 10.1016/j.molmet.2018.11.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 11/20/2018] [Accepted: 11/23/2018] [Indexed: 12/13/2022] Open
Abstract
OBJECTIVE Diabetic sensorimotor polyneuropathy (DSPN) affects approximately half of diabetic patients leading to significant morbidity. There is impaired neurotrophic growth factor signaling, AMP-activated protein kinase (AMPK) activity and mitochondrial function in dorsal root ganglia (DRG) of animal models of type 1 and type 2 diabetes. We hypothesized that sub-optimal insulin-like growth factor 1 (IGF-1) signaling in diabetes drives loss of AMPK activity and mitochondrial function, both contributing to development of DSPN. METHODS Age-matched control Sprague-Dawley rats and streptozotocin (STZ)-induced type 1 diabetic rats with/without IGF-1 therapy were used for in vivo studies. For in vitro studies, DRG neurons from control and STZ-diabetic rats were cultured and treated with/without IGF-1 in the presence or absence of inhibitors or siRNAs. RESULTS Dysregulation of mRNAs for IGF-1, AMPKα2, ATP5a1 (subunit of ATPase), and PGC-1β occurred in DRG of diabetic vs. control rats. IGF-1 up-regulated mRNA levels of these genes in cultured DRGs from control or diabetic rats. IGF-1 treatment of DRG cultures significantly (P < 0.05) increased phosphorylation of Akt, P70S6K, AMPK and acetyl-CoA carboxylase (ACC). Mitochondrial gene expression and oxygen consumption rate (spare respiratory capacity), ATP production, mtDNA/nDNA ratio and neurite outgrowth were augmented (P < 0.05). AMPK inhibitor, Compound C, or AMPKα1-specific siRNA suppressed IGF-1 elevation of mitochondrial function, mtDNA and neurite outgrowth. Diabetic rats treated with IGF-1 exhibited reversal of thermal hypoalgesia and, in a separate study, reversed the deficit in corneal nerve profiles. In diabetic rats, IGF-1 elevated the levels of AMPK and P70S6K phosphorylation, raised Complex IV-MTCO1 and Complex V-ATP5a protein expression, and restored the enzyme activities of Complex IV and I in the DRG. IGF-1 prevented TCA metabolite build-up in nerve. CONCLUSIONS In DRG neuron cultures IGF-1 signals via AMPK to elevate mitochondrial function and drive axonal outgrowth. We propose that this signaling axis mediates IGF-1-dependent protection from distal dying-back of fibers in diabetic neuropathy.
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Affiliation(s)
- Mohamad-Reza Aghanoori
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada
| | - Darrell R Smith
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Shiva Shariati-Ievari
- Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Canada
| | - Andrew Ajisebutu
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada
| | - Annee Nguyen
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Fiona Desmond
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Carlos H A Jesus
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Xiajun Zhou
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Nigel A Calcutt
- Department of Pathology, University of California San Diego, La Jolla, CA, USA
| | - Michel Aliani
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada; Canadian Centre for Agri-Food Research in Health and Medicine, St. Boniface Hospital Albrechtsen Research Centre, Winnipeg, Canada; Department of Physiology and Pathophysiology, University of Manitoba, Winnipeg, Canada
| | - Paul Fernyhough
- Division of Neurodegenerative Disorders, St Boniface Hospital Albrechtsen Research Centre, Winnipeg, MB, Canada; Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, MB, Canada.
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27
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Akiyama H, Nakadate K, Sakakibara SI. Synaptic localization of the SUMOylation-regulating protease SENP5 in the adult mouse brain. J Comp Neurol 2018; 526:990-1005. [DOI: 10.1002/cne.24384] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 12/04/2017] [Accepted: 12/11/2017] [Indexed: 02/06/2023]
Affiliation(s)
- Hiroki Akiyama
- Laboratory for Molecular Neurobiology, Faculty of Human Sciences; Waseda University; Tokorozawa Saitama 359-1192 Japan
| | - Kazuhiko Nakadate
- Department of Basic Science; Educational and Research Center for Pharmacy, Meiji Pharmaceutical University; Kiyose Tokyo 204-858 Japan
| | - Shin-ichi Sakakibara
- Laboratory for Molecular Neurobiology, Faculty of Human Sciences; Waseda University; Tokorozawa Saitama 359-1192 Japan
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28
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Yimer EM, Zewdie KA, Hishe HZ. Netrin as a Novel Biomarker and Its Therapeutic Implications in Diabetes Mellitus and Diabetes-Associated Complications. J Diabetes Res 2018; 2018:8250521. [PMID: 30320139 PMCID: PMC6167572 DOI: 10.1155/2018/8250521] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/14/2018] [Accepted: 09/04/2018] [Indexed: 12/16/2022] Open
Abstract
Diabetes is a multifactorial metabolic syndrome and is one of the shared long-lasting illnesses globally. It is linked to long-term microvascular and macrovascular complications that contribute to disability, compromised quality of life, and reduction in lifespan, which eventually leads to death. This disease is not only incurring significant economic burden but also adversely affects the patients, caregivers, communities, and the society at large. The interruption of diabetes progress and its complications is a primary focus of scientific communities. In spite of various diagnostic modalities for diabetes, there is a limited marker to investigate the risk and progress of its complications. Netrin has recently received more attention as a biomarker of diabetes and a broader range of long-term complication. Therefore, the impetus of this review is to exhaustively discuss the role of Netrin as a potential biomarker and its therapeutic implication in diabetes and diverse sets of microvascular and macrovascular complications of diabetes. It also discourses the possible mechanisms of Netrin for the said pharmacological effect for a better understanding of the development and progression of diabetes and its complications in relation to this protein. It enables protective measures to be applied at the subclinical stage and the responses to preventive or therapeutic measures to be scrutinized. Besides, it might also facilitate the appraisal of novel therapeutic options for diabetes and various complications through modifying the endogenous Netrin and provide surrogate endpoints for intervention.
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Affiliation(s)
- Ebrahim M. Yimer
- Department of Pharmacology and Toxicology, College of Health Sciences, Mekelle University, Ethiopia
| | - Kaleab Alemayehu Zewdie
- Department of Pharmacology and Toxicology, College of Health Sciences, Mekelle University, Ethiopia
| | - Hailemichael Zeru Hishe
- Department of Pharmacology and Toxicology, College of Health Sciences, Mekelle University, Ethiopia
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29
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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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30
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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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Smith G, Gallo G. To mdivi-1 or not to mdivi-1: Is that the question? Dev Neurobiol 2017; 77:1260-1268. [PMID: 28842943 DOI: 10.1002/dneu.22519] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 08/17/2017] [Accepted: 08/22/2017] [Indexed: 12/12/2022]
Abstract
The fission/division and fusion of mitochondria are fundamental aspects of mitochondrial biology. The balance of fission and fusion sets the length of mitochondria in cells to serve their physiological requirements. The fission of mitochondria is markedly induced in many disease states and in response to cellular injury, resulting in the fragmentation of mitochondria into dysfunctional units. The mechanism that drives fission is dependent on the dynamin related protein 1 (Drp1) GTPase. mdivi-1 is a quinazolinone originally described as a selective inhibitor of Drp1, over other dynamin family members, and reported to inhibit mitochondrial fission. A recent study has challenged the activity of mdivi-1 as an inhibitor of Drp1. This study raises serious issues regarding the interpretation of data addressing the effects of mdivi-1 as reflective of the inhibition of Drp1 and thus fission. This commentary considers the evidence for and against mdivi-1 as an inhibitor of Drp1 and presents the following considerations; (1) the activity of mdivi-1 toward Drp1 GTPase activity requires further biochemical investigation, (2) as there is a large body of literature using mdivi-1 in vitro with effects as predicted for inhibition of Drp1 and mitochondrial fission, reviewed herein, the evidence is in favor of mdivi-1's originally described bioactivity, and (3) until the issue is resolved, experimental interpretations for the effects of mdivi-1 on inhibition of fission in cell and tissue experiments warrants stringent positive controls directly addressing the effects of mdivi-1 on fission. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1260-1268, 2017.
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Affiliation(s)
- George Smith
- Department of Neuroscience, Lewis Katz School of Medicine, Temple University, 3500 North Broad Street, Philadelphia, Pennsylvania, 19140
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 North Broad Street, Philadelphia, Pennsylvania, 19140
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32
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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: 159] [Impact Index Per Article: 22.7] [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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Richetin K, Moulis M, Millet A, Arràzola MS, Andraini T, Hua J, Davezac N, Roybon L, Belenguer P, Miquel MC, Rampon C. Amplifying mitochondrial function rescues adult neurogenesis in a mouse model of Alzheimer's disease. Neurobiol Dis 2017; 102:113-124. [PMID: 28286181 DOI: 10.1016/j.nbd.2017.03.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 03/03/2017] [Accepted: 03/08/2017] [Indexed: 12/20/2022] Open
Abstract
Adult hippocampal neurogenesis is strongly impaired in Alzheimer's disease (AD). In several mouse models of AD, it was shown that adult-born neurons exhibit reduced survival and altered synaptic integration due to a severe lack of dendritic spines. In the present work, using the APPxPS1 mouse model of AD, we reveal that this reduced number of spines is concomitant of a marked deficit in their neuronal mitochondrial content. Remarkably, we show that targeting the overexpression of the pro-neural transcription factor Neurod1 into APPxPS1 adult-born neurons restores not only their dendritic spine density, but also their mitochondrial content and the proportion of spines associated with mitochondria. Using primary neurons, a bona fide model of neuronal maturation, we identified that increases of mitochondrial respiration accompany the stimulating effect of Neurod1 overexpression on dendritic growth and spine formation. Reciprocally, pharmacologically impairing mitochondria prevented Neurod1-dependent trophic effects. Thus, since overexpression of Neurod1 into new neurons of APPxPS1 mice rescues spatial memory, our present data suggest that manipulating the mitochondrial system of adult-born hippocampal neurons provides neuronal plasticity to the AD brain. These findings open new avenues for far-reaching therapeutic implications towards neurodegenerative diseases associated with cognitive impairment.
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Affiliation(s)
- Kevin Richetin
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Manon Moulis
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Aurélie Millet
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Macarena S Arràzola
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Trinovita Andraini
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France; Department of Physiology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | - Jennifer Hua
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Noélie Davezac
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Laurent Roybon
- Stem Cell Laboratory for CNS Diseases Modeling, Department of Experimental Medical Science, Wallenberg Neuroscience Center, Lund Stem Cell Center and MultiPark, Lund University, BMC A10, 221 84 Lund, Sweden
| | - Pascale Belenguer
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Marie-Christine Miquel
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France
| | - Claire Rampon
- Centre de Recherches sur la Cognition Animale, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, France.
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Faust A, Kandakatla A, van der Merwe Y, Ren T, Huleihel L, Hussey G, Naranjo JD, Johnson S, Badylak S, Steketee M. Urinary bladder extracellular matrix hydrogels and matrix-bound vesicles differentially regulate central nervous system neuron viability and axon growth and branching. J Biomater Appl 2017; 31:1277-1295. [PMID: 28447547 DOI: 10.1177/0885328217698062] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Central nervous system neurons often degenerate after trauma due to the inflammatory innate immune response to injury, which can lead to neuronal cell death, scarring, and permanently lost neurologic function. Extracellular matrix bioscaffolds, derived by decellularizing healthy tissues, have been widely used in both preclinical and clinical studies to promote positive tissue remodeling, including neurogenesis, in numerous tissues, with extracellular matrix from homologous tissues often inducing more positive responses. Extracellular matrix hydrogels are liquid at room temperature and enable minimally invasive extracellular matrix injections into central nervous system tissues, before gelation at 37℃. However, few studies have analyzed how extracellular matrix hydrogels influence primary central nervous system neuron survival and growth, and whether central nervous system and non-central nervous system extracellular matrix specificity is critical to neuronal responses. Urinary bladder extracellular matrix hydrogels increase both primary hippocampal neuron survival and neurite growth to similar or even greater extents, suggesting extracellular matrix from non-homologous tissue sources, such as urinary bladder matrix-extracellular matrix, may be a more economical and safer alternative to developing central nervous system extracellular matrices for central nervous system applications. Additionally, we show matrix-bound vesicles derived from urinary bladder extracellular matrix are endocytosed by hippocampal neurons and positively regulate primary hippocampal neuron neurite growth. Matrix-bound vesicles carry protein and RNA cargos, including noncoding RNAs and miRNAs that map to the human genome and are known to regulate cellular processes. Thus, urinary bladder matrix-bound vesicles provide natural and transfectable cargoes which offer new experimental tools and therapeutic applications to study and treat central nervous system neuron injury.
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Affiliation(s)
- Anne Faust
- 1 Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA
| | - Apoorva Kandakatla
- 1 Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA
| | - Yolandi van der Merwe
- 1 Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,3 Swanson School of Engineering, Department of Bioengineering University of Pittsburgh, Pittsburgh, PA, USA
| | - Tanchen Ren
- 1 Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA
| | - Luai Huleihel
- 2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,4 Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - George Hussey
- 2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,4 Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Juan Diego Naranjo
- 2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,4 Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Scott Johnson
- 2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,4 Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Stephen Badylak
- 2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,4 Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael Steketee
- 1 Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,2 McGowan Institute for Regenerative Medicine, Pittsburgh, PA, USA.,5 Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
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Flippo KH, Strack S. Mitochondrial dynamics in neuronal injury, development and plasticity. J Cell Sci 2017; 130:671-681. [PMID: 28154157 DOI: 10.1242/jcs.171017] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Mitochondria fulfill numerous cellular functions including ATP production, Ca2+ buffering, neurotransmitter synthesis and degradation, ROS production and sequestration, apoptosis and intermediate metabolism. Mitochondrial dynamics, a collective term for the processes of mitochondrial fission, fusion and transport, governs mitochondrial function and localization within the cell. Correct balance of mitochondrial dynamics is especially important in neurons as mutations in fission and fusion enzymes cause peripheral neuropathies and impaired development of the nervous system in humans. Regulation of mitochondrial dynamics is partly accomplished through post-translational modification of mitochondrial fission and fusion enzymes, in turn influencing mitochondrial bioenergetics and transport. The importance of post-translational regulation is highlighted by numerous neurodegenerative disorders associated with post-translational modification of the mitochondrial fission enzyme Drp1. Not surprisingly, mitochondrial dynamics also play an important physiological role in the development of the nervous system and synaptic plasticity. Here, we highlight recent findings underlying the mechanisms and regulation of mitochondrial dynamics in relation to neurological disease, as well as the development and plasticity of the nervous system.
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Affiliation(s)
- Kyle H Flippo
- Department of Pharmacology, University of Iowa, Iowa City, USA
| | - Stefan Strack
- Department of Pharmacology, University of Iowa, Iowa City, USA
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36
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Xu Y, Chen M, Hu B, Huang R, Hu B. In vivo Imaging of Mitochondrial Transport in Single-Axon Regeneration of Zebrafish Mauthner Cells. Front Cell Neurosci 2017; 11:4. [PMID: 28174522 PMCID: PMC5258718 DOI: 10.3389/fncel.2017.00004] [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: 10/18/2016] [Accepted: 01/09/2017] [Indexed: 12/17/2022] Open
Abstract
Mitochondrial transport is essential for neuronal function, but the evidence of connections between mitochondrial transport and axon regeneration in the central nervous system (CNS) of living vertebrates remains limited. Here, we developed a novel model to explore mitochondrial transport in a single Mauthner axon (M axon) of zebrafish with non-invasive in vivo imaging. To confirm the feasibility of using this model, we treated labeled zebrafish with nocodazole and demonstrated that it could disrupt mitochondrial transport. We also used two-photon laser axotomy to precisely axotomize M axons and simultaneously recorded their regeneration and the process of mitochondrial transport in living zebrafish larvae. The findings showed that the injured axons with stronger regenerative capability maintain greater mitochondrial motility. Furthermore, to stimulate axon regeneration, treatment with dibutyryl cyclic adenosine monophosphate (db-cAMP) could also augment mitochondrial motility. Taken together, our results provide new evidence that mitochondrial motility is positively correlated with axon regeneration in the living vertebrate CNS. This promising model will be useful for further studies on the interaction between axon regeneration and mitochondrial dynamics, using various genetic and pharmacological techniques.
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Affiliation(s)
- Yang Xu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Min Chen
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Bingbing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Rongchen Huang
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
| | - Bing Hu
- Chinese Academy of Sciences Key Laboratory of Brain Function and Disease, and School of Life Sciences, University of Science and Technology of China Hefei, China
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Valek L, Häussler A, Dröse S, Eaton P, Schröder K, Tegeder I. Redox-guided axonal regrowth requires cyclic GMP dependent protein kinase 1: Implication for neuropathic pain. Redox Biol 2016; 11:176-191. [PMID: 27978504 PMCID: PMC5156608 DOI: 10.1016/j.redox.2016.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/03/2016] [Accepted: 12/02/2016] [Indexed: 01/27/2023] Open
Abstract
Cyclic GMP-dependent protein kinase 1 (PKG1) mediates presynaptic nociceptive long-term potentiation (LTP) in the spinal cord and contributes to inflammatory pain in rodents but the present study revealed opposite effects in the context of neuropathic pain. We used a set of loss-of-function models for in vivo and in vitro studies to address this controversy: peripheral neuron specific deletion (SNS-PKG1-/-), inducible deletion in subsets of neurons (SLICK-PKG1-/-) and redox-dead PKG1 mutants. In contrast to inflammatory pain, SNS-PKG1-/- mice developed stronger neuropathic hyperalgesia associated with an impairment of nerve regeneration, suggesting specific repair functions of PKG1. Although PKG1 accumulated at the site of injury, its activity was lost in the proximal nerve due to a reduction of oxidation-dependent dimerization, which was a consequence of mitochondrial damage in injured axons. In vitro, PKG1 deficiency or its redox-insensitivity resulted in enhanced outgrowth and reduction of growth cone collapse in response to redox signals, which presented as oxidative hotspots in growing cones. At the molecular level, PKG1 deficiency caused a depletion of phosphorylated cofilin, which is essential for growth cone collapse and guidance. Hence, redox-mediated guidance required PKG1 and consequently, its deficiency in vivo resulted in defective repair and enhanced neuropathic pain after nerve injury. PKG1-dependent repair functions will outweigh its signaling functions in spinal nociceptive LTP, so that inhibition of PKG1 is no option for neuropathic pain. Axonal injury leads mitochondrial damage. The loss of signaling ROS is associated with a reduction of redox-dependent autoactivation of PKG1. Loss of PKG1 impairs peripheral nerve regeneration and aggravates neuropathic pain in mice. Oxidative hot spots are generated in spiky growth cones and trigger growth cone collapse via PKG1. Malfunctioning of this redox-PKG1 guided growth cone collapse leads to aberrant outgrowth.
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Affiliation(s)
- Lucie Valek
- Depts. of Clinical Pharmacology, Goethe-University Hospital, Frankfurt, Germany
| | - Annett Häussler
- Depts. of Clinical Pharmacology, Goethe-University Hospital, Frankfurt, Germany
| | - Stefan Dröse
- Depts. of Anaesthesiology, Goethe-University Hospital, Frankfurt, Germany
| | - Philipp Eaton
- King's College of London, Cardiovascular Division, The Rayne Institute, St. Thomas' Hospital, London, United Kingdom
| | - Katrin Schröder
- Depts. of Cardiovascular Physiology, Goethe-University Hospital, Frankfurt, Germany
| | - Irmgard Tegeder
- Depts. of Clinical Pharmacology, Goethe-University Hospital, Frankfurt, Germany.
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Sainath R, Ketschek A, Grandi L, Gallo G. CSPGs inhibit axon branching by impairing mitochondria-dependent regulation of actin dynamics and axonal translation. Dev Neurobiol 2016; 77:454-473. [PMID: 27429169 DOI: 10.1002/dneu.22420] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/28/2016] [Accepted: 07/14/2016] [Indexed: 12/27/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) inhibit the formation of axon collateral branches. The regulation of the axonal cytoskeleton and mitochondria are important components of the mechanism of branching. Actin-dependent axonal plasticity, reflected in the dynamics of axonal actin patches and filopodia, is greatest along segments of the axon populated by mitochondria. It is reported that CSPGs partially depolarize the membrane potential of axonal mitochondria, which impairs the dynamics of the axonal actin cytoskeleton and decreases the formation and duration of axonal filopodia, the first steps in the mechanism of branching. The effects of CSPGs on actin cytoskeletal dynamics are specific to axon segments populated by mitochondria. In contrast, CSPGs do not affect the microtubule content of axons, or the localization of microtubules into axonal filopodia, a required step in the mechanism of branch formation. It is also reported that CSPGs decrease the mitochondria-dependent axonal translation of cortactin, an actin associated protein involved in branching. Finally, the inhibitory effects of CSPGs on axon branching, actin cytoskeletal dynamics and the axonal translation of cortactin are reversed by culturing neurons with acetyl-l-carnitine, which promotes mitochondrial respiration. Collectively these data indicate that CSPGs impair mitochondrial function in axons, an effect which contributes to the inhibition of axon branching. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 419-437, 2017.
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Affiliation(s)
- Rajiv Sainath
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
| | - Andrea Ketschek
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
| | - Leah Grandi
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
| | - Gianluca Gallo
- Temple University School of Medicine, Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, 3500 N Broad St, Philadelphia, Pennsylvania
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A Small Molecule Activator of p300/CBP Histone Acetyltransferase Promotes Survival and Neurite Growth in a Cellular Model of Parkinson’s Disease. Neurotox Res 2016; 30:510-20. [DOI: 10.1007/s12640-016-9636-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Revised: 05/23/2016] [Accepted: 05/25/2016] [Indexed: 01/20/2023]
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Abstract
Krüppel-like factors (KLFs) are zinc finger transcription factors that share homology in three C-terminal zinc finger domains. KLF family members are expressed in most if not all tissues and have diverse roles in organismal development and cell differentiation, function, and death. The glomerular podocyte is particularly sensitive to mitochondrial dysfunction, as seen in various genetic disorders manifesting as progressive glomerulosclerosis. In this issue of the JCI, Mallipattu and coworkers show that KLF6 expression is reduced in mouse and human glomerular disease. Podocyte-specific deletion of Klf6 expression in mice leads to mitochondrial dysfunction and apoptosis, followed by glomerulosclerosis. This is the first demonstration that defective transcriptional regulation of nuclear-encoded mitochondrial genes can result in experimental glomerular disease.
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Kador KE, Alsehli HS, Zindell AN, Lau LW, Andreopoulos FM, Watson BD, Goldberg JL. Retinal ganglion cell polarization using immobilized guidance cues on a tissue-engineered scaffold. Acta Biomater 2014; 10:4939-4946. [PMID: 25194930 PMCID: PMC4254021 DOI: 10.1016/j.actbio.2014.08.032] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 07/28/2014] [Accepted: 08/27/2014] [Indexed: 12/30/2022]
Abstract
Cell transplantation therapies to treat diseases related to dysfunction of retinal ganglion cells (RGCs) are limited in part by an inability to navigate to the optic nerve head within the retina. During development, RGCs are guided by a series of neurotrophic factors and guidance cues; however, these factors and their receptors on the RGCs are developmentally regulated and often not expressed during adulthood. Netrin-1 is a guidance factor capable of guiding RGCs in culture and relevant to guiding RGC axons toward the optic nerve head in vivo. Here we immobilized Netrin-1 using UV-initiated crosslinking to form a gradient capable of guiding the axonal growth of RGCs on a radial electrospun scaffold. Netrin-gradient scaffolds promoted both the percentage of RGCs polarized with a single axon, and also the percentage of cells polarized toward the scaffold center, from 31% to 52%. Thus, an immobilized protein gradient on a radial electrospun scaffold increases RGC axon growth in a direction consistent with developmental optic nerve head guidance, and may prove beneficial for use in cell transplant therapies for the treatment of glaucoma and other optic neuropathies.
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Affiliation(s)
- Karl E Kador
- Shiley Eye Center and Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA 92093, USA; Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, FL 33136, USA
| | - Haneen S Alsehli
- Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, FL 33136, USA; Department of Biomedical Sciences, Barry University, Miami Shores, FL 33161, USA
| | - Allison N Zindell
- Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, FL 33136, USA; Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33136, USA
| | - Lung W Lau
- Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, FL 33136, USA
| | - Fotios M Andreopoulos
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33136, USA; Department of Surgery, Miller School of Medicine, University of Miami, FL 33136, USA
| | - Brant D Watson
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33136, USA; Department of Neurology, Miller School of Medicine, University of Miami, FL 33136, USA
| | - Jeffrey L Goldberg
- Shiley Eye Center and Institute of Engineering in Medicine, University of California San Diego, La Jolla, CA 92093, USA; Bascom Palmer Eye Institute and Interdisciplinary Stem Cell Institute, Miller School of Medicine, University of Miami, FL 33136, USA.
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Sainath R, Gallo G. The dynein inhibitor Ciliobrevin D inhibits the bidirectional transport of organelles along sensory axons and impairs NGF-mediated regulation of growth cones and axon branches. Dev Neurobiol 2014; 75:757-77. [PMID: 25404503 DOI: 10.1002/dneu.22246] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 11/10/2014] [Accepted: 11/12/2014] [Indexed: 11/11/2022]
Abstract
The axonal transport of organelles is critical for the development, maintenance, and survival of neurons, and its dysfunction has been implicated in several neurodegenerative diseases. Retrograde axon transport is mediated by the motor protein dynein. In this study, using embryonic chicken dorsal root ganglion neurons, we investigate the effects of Ciliobrevin D, a pharmacological dynein inhibitor, on the transport of axonal organelles, axon extension, nerve growth factor (NGF)-induced branching and growth cone expansion, and axon thinning in response to actin filament depolymerization. Live imaging of mitochondria, lysosomes, and Golgi-derived vesicles in axons revealed that both the retrograde and anterograde transport of these organelles was inhibited by treatment with Ciliobrevin D. Treatment with Ciliobrevin D reversibly inhibits axon extension and transport, with effects detectable within the first 20 min of treatment. NGF induces growth cone expansion, axonal filopodia formation and branching. Ciliobrevin D prevented NGF-induced formation of axonal filopodia and branching but not growth cone expansion. Finally, we report that the retrograde reorganization of the axonal cytoplasm which occurs on actin filament depolymerization is inhibited by treatment with Ciliobrevin D, indicating a role for microtubule based transport in this process, as well as Ciliobrevin D accelerating Wallerian degeneration. This study identifies Ciliobrevin D as an inhibitor of the bidirectional transport of multiple axonal organelles, indicating this drug may be a valuable tool for both the study of dynein function and a first pass analysis of the role of axonal transport.
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Affiliation(s)
- Rajiv Sainath
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, 3500 N Broad St, Philadelphia, Pennsylvania, 19140
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, 3500 N Broad St, Philadelphia, Pennsylvania, 19140
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Mitochondria modify exercise-induced development of stem cell-derived neurons in the adult brain. J Neurosci 2014; 34:6624-33. [PMID: 24806687 DOI: 10.1523/jneurosci.4972-13.2014] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Neural stem cells in the adult mammalian hippocampus continuously generate new functional neurons, which modify the hippocampal network and significantly contribute to cognitive processes and mood regulation. Here, we show that the development of new neurons from stem cells in adult mice is paralleled by extensive changes to mitochondrial mass, distribution, and shape. Moreover, exercise-a strong modifier of adult hippocampal neurogenesis-accelerates neuronal maturation and induces a profound increase in mitochondrial content and the presence of mitochondria in dendritic segments. Genetic inhibition of the activity of the mitochondrial fission factor dynamin-related protein 1 (Drp1) inhibits neurogenesis under basal and exercise conditions. Conversely, enhanced Drp1 activity furthers exercise-induced acceleration of neuronal maturation. Collectively, these results indicate that adult hippocampal neurogenesis requires adaptation of the mitochondrial compartment and suggest that mitochondria are targets for enhancing neurogenesis-dependent hippocampal plasticity.
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Spillane M, Ketschek A, Merianda TT, Twiss JL, Gallo G. Mitochondria coordinate sites of axon branching through localized intra-axonal protein synthesis. Cell Rep 2013; 5:1564-75. [PMID: 24332852 DOI: 10.1016/j.celrep.2013.11.022] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Revised: 09/30/2013] [Accepted: 11/12/2013] [Indexed: 11/16/2022] Open
Abstract
The branching of axons is a fundamental aspect of nervous system development and neuroplasticity. We report that branching of sensory axons in the presence of nerve growth factor (NGF) occurs at sites populated by stalled mitochondria. Translational machinery targets to presumptive branching sites, followed by recruitment of mitochondria to these sites. The mitochondria promote branching through ATP generation and the determination of localized hot spots of active axonal mRNA translation, which contribute to actin-dependent aspects of branching. In contrast, mitochondria do not have a role in the regulation of the microtubule cytoskeleton during NGF-induced branching. Collectively, these observations indicate that sensory axons exhibit multiple potential sites of translation, defined by presence of translational machinery, but active translation occurs following the stalling and respiration of mitochondria at these potential sites of translation. This study reveals a local role for axonal mitochondria in the regulation of the actin cytoskeleton and axonal mRNA translation underlying branching.
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Affiliation(s)
- Mirela Spillane
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Andrea Ketschek
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA
| | - Tanuja T Merianda
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19210, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, 715 Sumter Street, Columbia, SC 29208, USA
| | - Gianluca Gallo
- Department of Anatomy and Cell Biology, Shriners Hospitals Pediatric Research Center, Temple University, 3500 North Broad Street, Philadelphia, PA 19140, USA.
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Lathrop KL, Steketee MB. Mitochondrial Dynamics in Retinal Ganglion Cell Axon Regeneration and Growth Cone Guidance. JOURNAL OF OCULAR BIOLOGY 2013; 1:9. [PMID: 24616897 PMCID: PMC3946936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Failed axon regeneration and retinal ganglion cell (RGC) death after trauma or disease, including glaucomatous and mitochondrial optic neuropathies, are increasingly linked to mitochondrial dysfunction. Mitochondria are highly dynamic organelles whose size, organization, and function are regulated by a balance between mitochondrial fission and fusion. Mitochondria are ubiquitous in axonal growth cones both in vitro and in vivo and during development and regeneration. However, the roles that mitochondrial fission and fusion dynamics play in the growth cone during axon regeneration are largely unstudied. Here we discuss recent data suggesting mitochondria in the distal axon and growth cone play a central role in axon growth by integrating intrinsic axon growth states with signaling from extrinsic cues. Mitochondrial fission and fusion are intrinsically regulated in the distal axon in the growth cones of acutely purified embryonic and postnatal RGCs with differing intrinsic axon growth potentials. These differences in fission and fusion correlate with differences in mitochondrial bioenergetics; embryonic RGCs with high intrinsic axon growth potential rely more on glycolysis whereas RGCs with low intrinsic axon growth potential rely more on oxidative phosphorylation. Mitochondrial fission and fusion are also differentially modulated by KLFs that either promote or suppress intrinsic axon growth, and altering the balance between mitochondrial fission and fusion can differentially regulate axon growth rate and growth cone guidance responses to both inhibitory and permissive guidance cues.
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Affiliation(s)
- Kira L. Lathrop
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
- Swanson School of Engineering, Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michael B. Steketee
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
- Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
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46
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Kaden TR, Li W. AUTOPHAGY, MITOCHONDRIAL DYNAMICS AND RETINAL DISEASES. Asia Pac J Ophthalmol (Phila) 2013; 2:S2162-0989(23)01010-1. [PMID: 24205447 PMCID: PMC3816775 DOI: 10.1097/apo.0b013e31829d3e33] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Talia R. Kaden
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
- Yale University School of Medicine, New Haven, CT, USA
| | - Wei Li
- National Eye Institute, National Institutes of Health, Bethesda, MD, USA
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