1
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Chandra S, Chatterjee R, Olmsted ZT, Mukherjee A, Paluh JL. Axonal transport during injury on a theoretical axon. Front Cell Neurosci 2023; 17:1215945. [PMID: 37636588 PMCID: PMC10450981 DOI: 10.3389/fncel.2023.1215945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 07/12/2023] [Indexed: 08/29/2023] Open
Abstract
Neurodevelopment, plasticity, and cognition are integral with functional directional transport in neuronal axons that occurs along a unique network of discontinuous polar microtubule (MT) bundles. Axonopathies are caused by brain trauma and genetic diseases that perturb or disrupt the axon MT infrastructure and, with it, the dynamic interplay of motor proteins and cargo essential for axonal maintenance and neuronal signaling. The inability to visualize and quantify normal and altered nanoscale spatio-temporal dynamic transport events prevents a full mechanistic understanding of injury, disease progression, and recovery. To address this gap, we generated DyNAMO, a Dynamic Nanoscale Axonal MT Organization model, which is a biologically realistic theoretical axon framework. We use DyNAMO to experimentally simulate multi-kinesin traffic response to focused or distributed tractable injury parameters, which are MT network perturbations affecting MT lengths and multi-MT staggering. We track kinesins with different motility and processivity, as well as their influx rates, in-transit dissociation and reassociation from inter-MT reservoirs, progression, and quantify and spatially represent motor output ratios. DyNAMO demonstrates, in detail, the complex interplay of mixed motor types, crowding, kinesin off/on dissociation and reassociation, and injury consequences of forced intermingling. Stalled forward progression with different injury states is seen as persistent dynamicity of kinesins transiting between MTs and inter-MT reservoirs. DyNAMO analysis provides novel insights and quantification of axonal injury scenarios, including local injury-affected ATP levels, as well as relates these to influences on signaling outputs, including patterns of gating, waves, and pattern switching. The DyNAMO model significantly expands the network of heuristic and mathematical analysis of neuronal functions relevant to axonopathies, diagnostics, and treatment strategies.
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Affiliation(s)
- Soumyadeep Chandra
- Electrical and Computer Science Engineering, Purdue University, West Lafayette, IN, United States
| | - Rounak Chatterjee
- Department of Electronics, Electrical and Systems Engineering, University of Birmingham, Birmingham, United Kingdom
| | - Zachary T. Olmsted
- Nanobioscience, College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, NY, United States
- Department of Neurosurgery, Ronald Reagan UCLA Medical Center, University of California, Los Angeles, Los Angeles, CA, United States
| | - Amitava Mukherjee
- Nanobioscience, College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, NY, United States
- School of Computing, Amrita Vishwa Vidyapeetham (University), Kollam, Kerala, India
| | - Janet L. Paluh
- Nanobioscience, College of Nanoscale Science and Engineering, State University of New York Polytechnic Institute, Albany, NY, United States
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2
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Abstract
Neurons are markedly compartmentalized, which makes them reliant on axonal transport to maintain their health. Axonal transport is important for anterograde delivery of newly synthesized macromolecules and organelles from the cell body to the synapse and for the retrograde delivery of signaling endosomes and autophagosomes for degradation. Dysregulation of axonal transport occurs early in neurodegenerative diseases and plays a key role in axonal degeneration. Here, we provide an overview of mechanisms for regulation of axonal transport; discuss how these mechanisms are disrupted in neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, hereditary spastic paraplegia, amyotrophic lateral sclerosis, and Charcot-Marie-Tooth disease; and discuss therapeutic approaches targeting axonal transport.
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3
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In vivo imaging of axonal transport in peripheral nerves of rodent forelimbs. Neuronal Signal 2023; 7:NS20220098. [PMID: 36743438 PMCID: PMC9867938 DOI: 10.1042/ns20220098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/23/2022] [Accepted: 01/05/2023] [Indexed: 01/07/2023] Open
Abstract
Axonal transport is the essential process by which neurons actively traffic a variety of cargoes between the cell soma and axon terminals. Accordingly, dysfunctional axonal transport is linked to many nervous system conditions. Therefore, being able to image and quantify this dynamic process in live neurons of animal disease models is beneficial for understanding neuropathology and testing new therapies at the preclinical level. As such, intravital approaches have been developed to assess cargo movement in the hindlimb sciatic nerves of live, anaesthetised mice. Here, we describe an adapted method for in vivo imaging of axonal transport in intact median and ulnar nerves of the rodent forelimb. Injection of a fluorescently labelled and non-toxic fragment of tetanus neurotoxin (HCT) into the mouse forepaw permits the identification of signalling endosomes in intact axons of median and ulnar nerves. Through immunofluorescent analysis of forelimb lumbrical muscles and median/ulnar nerves, we confirmed that HCT is taken up at motor nerve terminals and predominantly locates to motor axons. We then showed that the baseline trafficking of signalling endosomes is similar between the median/ulnar nerves and the sciatic nerve in adult wild-type mice. Importantly, this adapted method can be readily tailored for assessment of additional cargoes, such as mitochondria. By measuring transport in forelimb and hindlimb nerves, comparative anatomical and functional analyses can be performed in rodent disease models to aid our understanding of peripheral nerve disease pathogenesis and response to injury.
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4
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Grimaud B, Frétaud M, Terras F, Bénassy A, Duroure K, Bercier V, Trippé-Allard G, Mohammedi R, Gacoin T, Del Bene F, Marquier F, Langevin C, Treussart F. In Vivo Fast Nonlinear Microscopy Reveals Impairment of Fast Axonal Transport Induced by Molecular Motor Imbalances in the Brain of Zebrafish Larvae. ACS NANO 2022; 16:20470-20487. [PMID: 36459488 DOI: 10.1021/acsnano.2c06799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Cargo transport by molecular motors along microtubules is essential for the function of eukaryotic cells, in particular neurons in which axonal transport defects constitute the early pathological features of neurodegenerative diseases. Mainly studied in motor and sensory neurons, axonal transport is still difficult to characterize in neurons of the brain in absence of appropriate in vivo tools. Here, we measured fast axonal transport by tracing the second harmonic generation (SHG) signal of potassium titanyl phosphate (KTP) nanocrystals (nanoKTP) endocytosed by brain neurons of zebrafish (Zf) larvae. Thanks to the optical translucency of Zf larvae and to the perfect photostability of nanoKTP SHG, we achieved a high scanning speed of 20 frames (of ≈90 μm × 60 μm size) per second in Zf brain. We focused our study on endolysosomal vesicle transport in axons of known polarization, separately analyzing kinesin and dynein motor-driven displacements. To validate our assay, we used either loss-of-function mutations of dynein or kinesin 1 or the dynein inhibitor dynapyrazole and quantified several transport parameters. We successfully demonstrated that dynapyrazole reduces the nanoKTP mobile fraction and retrograde run length consistently, while the retrograde run length increased in kinesin 1 mutants. Taking advantage of nanoKTP SHG directional emission, we also quantified fluctuations of vesicle orientation. Thus, by combining endocytosis of nanocrystals having a nonlinear response, fast two-photon microscopy, and high-throughput analysis, we are able to finely monitor fast axonal transport in vivo in the brain of a vertebrate and reveal subtle axonal transport alterations. The high spatiotemporal resolution achieved in our model may be relevant to precisely investigate axonal transport impairment associated with disease models.
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Affiliation(s)
- Baptiste Grimaud
- ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, Université Paris-Saclay, 91190Gif-sur-Yvette, France
| | - Maxence Frétaud
- INRAE, IERP, Université Paris-Saclay, 78350Jouy-ens-Josas, France
- INRAE, VIM, Université Paris-Saclay, 78350Jouy-en-Josas, France
| | - Feriel Terras
- ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, Université Paris-Saclay, 91190Gif-sur-Yvette, France
| | - Antoine Bénassy
- ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, Université Paris-Saclay, 91190Gif-sur-Yvette, France
| | - Karine Duroure
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, 75012Paris, France
| | - Valérie Bercier
- Center for Brain and Disease Research, Laboratory of Neurobiology, VIB, 3000Leuven, Belgium
| | - Gaëlle Trippé-Allard
- ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, Université Paris-Saclay, 91190Gif-sur-Yvette, France
| | - Rabei Mohammedi
- Laboratory of Condensed Matter Physics, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, 91128Palaiseau Cedex, France
| | - Thierry Gacoin
- Laboratory of Condensed Matter Physics, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, 91128Palaiseau Cedex, France
| | - Filippo Del Bene
- INSERM, CNRS, Institut de la Vision, Sorbonne Université, 75012Paris, France
| | - François Marquier
- ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, Université Paris-Saclay, 91190Gif-sur-Yvette, France
| | | | - François Treussart
- ENS Paris-Saclay, CNRS, CentraleSupélec, LuMIn, Université Paris-Saclay, 91190Gif-sur-Yvette, France
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5
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Tosolini AP, Sleigh JN, Surana S, Rhymes ER, Cahalan SD, Schiavo G. BDNF-dependent modulation of axonal transport is selectively impaired in ALS. Acta Neuropathol Commun 2022; 10:121. [PMID: 35996201 PMCID: PMC9396851 DOI: 10.1186/s40478-022-01418-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Accepted: 07/29/2022] [Indexed: 02/08/2023] Open
Abstract
Axonal transport ensures long-range delivery of essential cargoes between proximal and distal compartments, and is needed for neuronal development, function, and survival. Deficits in axonal transport have been detected at pre-symptomatic stages in the SOD1G93A and TDP-43M337V mouse models of amyotrophic lateral sclerosis (ALS), suggesting that impairments in this critical process are fundamental for disease pathogenesis. Strikingly, in ALS, fast motor neurons (FMNs) degenerate first whereas slow motor neurons (SMNs) are more resistant, and this is a currently unexplained phenomenon. The main aim of this investigation was to determine the effects of brain-derived neurotrophic factor (BDNF) on in vivo axonal transport in different α-motor neuron (MN) subtypes in wild-type (WT) and SOD1G93A mice. We report that despite displaying similar basal transport speeds, stimulation of wild-type MNs with BDNF enhances in vivo trafficking of signalling endosomes specifically in FMNs. This BDNF-mediated enhancement of transport was also observed in primary ventral horn neuronal cultures. However, FMNs display selective impairment of axonal transport in vivo in symptomatic SOD1G93A mice, and are refractory to BDNF stimulation, a phenotype that was also observed in primary embryonic SOD1G93A neurons. Furthermore, symptomatic SOD1G93A mice display upregulation of the classical non-pro-survival truncated TrkB and p75NTR receptors in muscles, sciatic nerves, and Schwann cells. Altogether, these data indicate that cell- and non-cell autonomous BDNF signalling is impaired in SOD1G93A MNs, thus identifying a new key deficit in ALS.
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Affiliation(s)
- Andrew P Tosolini
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
- UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK.
| | - James N Sleigh
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
| | - Sunaina Surana
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK
| | - Elena R Rhymes
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK
- UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK
| | - Stephen D Cahalan
- Comparative Neuromuscular Disease Laboratory, Department of Clinical Sciences and Services, Royal Veterinary College, University of London, London, NW1 0TU, UK
| | - Giampietro Schiavo
- Department of Neuromuscular Diseases, Queen Square Institute of Neurology, University College London, London, WC1N 3BG, UK.
- UCL Queen Square Motor Neuron Disease Centre, University College London, London, WC1N 3BG, UK.
- UK Dementia Research Institute, University College London, London, WC1E 6BT, UK.
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6
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Dias MS, Luo X, Ribas VT, Petrs-Silva H, Koch JC. The Role of Axonal Transport in Glaucoma. Int J Mol Sci 2022; 23:ijms23073935. [PMID: 35409291 PMCID: PMC8999615 DOI: 10.3390/ijms23073935] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Revised: 03/28/2022] [Accepted: 03/31/2022] [Indexed: 11/16/2022] Open
Abstract
Glaucoma is a neurodegenerative disease that affects the retinal ganglion cells (RGCs) and leads to progressive vision loss. The first pathological signs can be seen at the optic nerve head (ONH), the structure where RGC axons leave the retina to compose the optic nerve. Besides damage of the axonal cytoskeleton, axonal transport deficits at the ONH have been described as an important feature of glaucoma. Axonal transport is essential for proper neuronal function, including transport of organelles, synaptic components, vesicles, and neurotrophic factors. Impairment of axonal transport has been related to several neurodegenerative conditions. Studies on axonal transport in glaucoma include analysis in different animal models and in humans, and indicate that its failure happens mainly in the ONH and early in disease progression, preceding axonal and somal degeneration. Thus, a better understanding of the role of axonal transport in glaucoma is not only pivotal to decipher disease mechanisms but could also enable early therapies that might prevent irreversible neuronal damage at an early time point. In this review we present the current evidence of axonal transport impairment in glaucomatous neurodegeneration and summarize the methods employed to evaluate transport in this disease.
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Affiliation(s)
- Mariana Santana Dias
- Intermediate Laboratory of Gene Therapy and Viral Vectors, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (M.S.D.); (H.P.-S.)
| | - Xiaoyue Luo
- Department of Neurology, University Medical Center Göttingen, 37077 Göttingen, Germany;
| | - Vinicius Toledo Ribas
- Laboratory of Neurobiology, Department of Morphology, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte 31270-901, Brazil;
| | - Hilda Petrs-Silva
- Intermediate Laboratory of Gene Therapy and Viral Vectors, Carlos Chagas Filho Biophysics Institute, Federal University of Rio de Janeiro, Rio de Janeiro 21941-902, Brazil; (M.S.D.); (H.P.-S.)
| | - Jan Christoph Koch
- Department of Neurology, University Medical Center Göttingen, 37077 Göttingen, Germany;
- Correspondence:
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7
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Sahoo PK, Willis DE, Sleigh JN. Editorial: Pathways and Processes Underpinning Axonal Biology and Pathobiology. Front Mol Neurosci 2022; 15:883244. [PMID: 35401108 PMCID: PMC8984018 DOI: 10.3389/fnmol.2022.883244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Accepted: 03/02/2022] [Indexed: 11/13/2022] Open
Affiliation(s)
- Pabitra K. Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Dianna E. Willis
- Burke Neurological Institute, White Plains, NY, United States
- Feil Family Brain & Mind Research Institute, Weill Cornell Medicine, New York, NY, United States
| | - James N. Sleigh
- Department of Neuromuscular Diseases and UCL Queen Square Motor Neuron Disease Centre, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
- UK Dementia Research Institute, University College London, London, United Kingdom
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8
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Annuario E, Ng K, Vagnoni A. High-Resolution Imaging of Mitochondria and Mitochondrial Nucleoids in Differentiated SH-SY5Y Cells. Methods Mol Biol 2022; 2431:291-310. [PMID: 35412283 DOI: 10.1007/978-1-0716-1990-2_15] [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] [Indexed: 10/18/2022]
Abstract
Mitochondria are highly dynamic organelles which form intricate networks with complex dynamics. Mitochondrial transport and distribution are essential to ensure proper cell function, especially in cells with an extremely polarised morphology such as neurons. A layer of complexity is added when considering mitochondria have their own genome, packaged into nucleoids. Major mitochondrial morphological transitions, for example mitochondrial division, often occur in conjunction with mitochondrial DNA (mtDNA) replication and changes in the dynamic behaviour of the nucleoids. However, the relationship between mtDNA dynamics and mitochondrial motility in the processes of neurons has been largely overlooked. In this chapter, we describe a method for live imaging of mitochondria and nucleoids in differentiated SH-SY5Y cells by instant structured illumination microscopy (iSIM). We also include a detailed protocol for the differentiation of SH-SY5Y cells into cells with a pronounced neuronal-like morphology and show examples of coordinated mitochondrial and nucleoid motility in the long processes of these cells.
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Affiliation(s)
- Emily Annuario
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Kristal Ng
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Alessio Vagnoni
- Department of Basic and Clinical Neurosciences, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK.
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9
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Voelzmann A, Sanchez-Soriano N. Drosophila Primary Neuronal Cultures as a Useful Cellular Model to Study and Image Axonal Transport. Methods Mol Biol 2022; 2431:429-449. [PMID: 35412291 DOI: 10.1007/978-1-0716-1990-2_23] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The use of primary neuronal cultures generated from Drosophila tissue provides a powerful model for studies of transport mechanisms. Cultured fly neurons provide similarly detailed subcellular resolution and applicability of pharmacology or fluorescent dyes as mammalian primary neurons. As an experimental advantage for the mechanistic dissection of transport, fly primary neurons can be combined with the fast and highly efficient combinatorial genetics of Drosophila, and genetic tools for the manipulation of virtually every fly gene are readily available. This strategy can be performed in parallel to in vivo transport studies to address relevance of any findings. Here we will describe the generation of primary neuronal cultures from Drosophila embryos and larvae, the use of external fluorescent dyes and genetic tools to label cargo, and the key strategies for live imaging and subsequent analysis.
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Affiliation(s)
- André Voelzmann
- School of Biological Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
| | - Natalia Sanchez-Soriano
- Department of Molecular Physiology & Cell Signalling, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, UK.
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10
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Ionescu A, Perlson E. Microfluidic Neuromuscular Co-culture System for Tracking Cell-to-Cell Transfer and Axonal Transport of Labeled Proteins. Methods Mol Biol 2022; 2431:145-161. [PMID: 35412275 DOI: 10.1007/978-1-0716-1990-2_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The molecular communication mechanisms within the Motor Neurons (MN) distant axon and its soma, as well as between MN and their neighboring cells and extracellular environment are of keen interest for our understanding of neurodevelopment and neurodegenerative diseases. One tool that has significantly improved our ability to study such processes with high spatiotemporal resolution is microfluidic devices. Here we describe a step-by-step guide to the neuromuscular co-culturing procedure and demonstrate how to track trophic factors transmission from muscle-to-neuron and their transport along the axons.
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Affiliation(s)
- Ariel Ionescu
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel
| | - Eran Perlson
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Tel Aviv, Israel.
- The Sagol School of Neuroscience, Tel-Aviv University, Tel Aviv, Israel.
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11
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Villarroel-Campos D, Schiavo G, Sleigh JN. Dissection, in vivo imaging and analysis of the mouse epitrochleoanconeus muscle. J Anat 2021; 241:1108-1119. [PMID: 34121181 PMCID: PMC9558155 DOI: 10.1111/joa.13478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/07/2021] [Accepted: 05/18/2021] [Indexed: 12/25/2022] Open
Abstract
Analysis of rodent muscles affords an opportunity to glean key insights into neuromuscular development and the detrimental impact of disease‐causing genetic mutations. Muscles of the distal leg, for instance the gastrocnemius and tibialis anterior, are commonly used in such studies with mice and rats. However, thin and flat muscles, which can be dissected, processed and imaged without major disruption to muscle fibres and nerve‐muscle contacts, are more suitable for accurate and detailed analyses of the peripheral motor nervous system. One such wholemount muscle is the predominantly fast twitch epitrochleoanconeus (ETA), which is located in the upper forelimb, innervated by the radial nerve, and contains relatively large and uniformly flat neuromuscular junctions (NMJs). To facilitate incorporation of the ETA into the experimental toolkit of the neuromuscular disease field, here, we describe a simple method for its rapid isolation (<5 min), supported by high‐resolution videos and step‐by‐step images. Furthermore, we outline how the ETA can be imaged in live, anaesthetised mice, to enable examination of dynamic cellular processes occurring at the NMJ and within intramuscular axons, including transport of organelles, such as mitochondria and signalling endosomes. Finally, we present reference data on wild‐type ETA fibre‐type composition in young adult, male C57BL6/J mice. Comparative neuroanatomical studies of different muscles in rodent models of disease can generate critical insights into pathogenesis and pathology; dissection of the wholemount ETA provides the possibility to diversify the repertoire of muscles analysed for this endeavour.
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Affiliation(s)
- David Villarroel-Campos
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - 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
| | - 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
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12
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Bagalkot TR, Block ER, Bucchin K, Balcita-Pedicino JJ, Calderon M, Sesack SR, Sorkin A. Dopamine Transporter Localization in Medial Forebrain Bundle Axons Indicates Its Long-Range Transport Primarily by Membrane Diffusion with a Limited Contribution of Vesicular Traffic on Retromer-Positive Compartments. J Neurosci 2021; 41:234-250. [PMID: 33234607 PMCID: PMC7810657 DOI: 10.1523/jneurosci.0744-20.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 11/05/2020] [Accepted: 11/13/2020] [Indexed: 12/18/2022] Open
Abstract
Dopamine transporter (DAT) controls dopamine neurotransmission by clearing synaptically released dopamine. However, trafficking itineraries of DAT, which determine its cell-surface concentration near synapses, are poorly characterized. It is especially unknown how DAT is transported between spatially distant midbrain somatodendritic and striatal axonal compartments. To examine this "long-range" trafficking, the localization and membrane diffusion of HA-epitope tagged DAT in the medial forebrain bundle (MFB) of a knock-in mouse (both sexes) were analyzed using confocal, super-resolution and EM in intact brain and acute brain slices. HA-DAT was abundant in the plasma membrane of MFB axons, similar to the striatum, although the intracellular fraction of HA-DAT in MFB was more substantial. Intracellular HA-DAT colocalized with VPS35, a subunit of the retromer complex mediating recycling from endosomes, in a subset of axons. Late endosomes, lysosomes, and endoplasmic reticulum were abundant in the soma but minimally present in MFB axons, suggesting that biosynthesis and lysosomal degradation of DAT are confined to soma. Together, the data suggest that membrane diffusion is the main mode of long-range DAT transport through MFB, although the contribution of vesicular traffic can be significant in a population of MFB axons. Based on HA-DAT diffusion rates, plasma membrane DAT in MFB axons turns over with a halftime of ∼20 d, which explains the extremely slow turnover of DAT protein in the brain. Unexpectedly, the mean diameter of DAT-labeled MFB axons was observed to be twice larger than reported for striatum. The implications of this finding for dopamine neuron physiology are discussed.SIGNIFICANCE STATEMENT The dopamine transporter (DAT) is a key regulator of dopamine neurotransmission and a target of abused psychostimulants. In the present study, we examined, for the first time, mechanisms of the long-range traffic of DAT in intact brain and acute brain slices from the knock-in mouse expressing epitope-tagged DAT. Using a combination of confocal, super-resolution and EM, we defined DAT localization and its membrane diffusion parameters in medial forebrain bundle axonal tracts connecting midbrain somatodendritic and striatal axonal compartments of dopaminergic neurons. In contrast to the widely accepted model of long-range axonal transport, our studies suggest that DAT traffics between midbrain and striatum, mainly by lateral diffusion in the plasma membrane with only a limited contribution of vesicular transport in recycling endosomes.
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Affiliation(s)
- Tarique R Bagalkot
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Ethan R Block
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
- Chatham University, Pittsburgh, Pennsylvania 15232
| | - Kristen Bucchin
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Judith Joyce Balcita-Pedicino
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Michael Calderon
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Susan R Sesack
- Department of Neuroscience, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15213
| | - Alexander Sorkin
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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13
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Tosolini AP, Sleigh JN. Intramuscular Delivery of Gene Therapy for Targeting the Nervous System. Front Mol Neurosci 2020; 13:129. [PMID: 32765219 PMCID: PMC7379875 DOI: 10.3389/fnmol.2020.00129] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 06/26/2020] [Indexed: 12/11/2022] Open
Abstract
Virus-mediated gene therapy has the potential to deliver exogenous genetic material into specific cell types to promote survival and counteract disease. This is particularly enticing for neuronal conditions, as the nervous system is renowned for its intransigence to therapeutic targeting. Administration of gene therapy viruses into skeletal muscle, where distal terminals of motor and sensory neurons reside, has been shown to result in extensive transduction of cells within the spinal cord, brainstem, and sensory ganglia. This route is minimally invasive and therefore clinically relevant for gene therapy targeting to peripheral nerve soma. For successful transgene expression, viruses administered into muscle must undergo a series of processes, including host cell interaction and internalization, intracellular sorting, long-range retrograde axonal transport, endosomal liberation, and nuclear import. In this review article, we outline key characteristics of major gene therapy viruses—adenovirus, adeno-associated virus (AAV), and lentivirus—and summarize the mechanisms regulating important steps in the virus journey from binding at peripheral nerve terminals to nuclear delivery. Additionally, we describe how neuropathology can negatively influence these pathways, and conclude by discussing opportunities to optimize the intramuscular administration route to maximize gene delivery and thus therapeutic potential.
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Affiliation(s)
- Andrew P Tosolini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom
| | - James N Sleigh
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, United Kingdom.,UK Dementia Research Institute, University College London, London, United Kingdom
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14
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Smart motors and cargo steering drive kinesin-mediated selective transport. Mol Cell Neurosci 2020; 103:103464. [PMID: 31972342 DOI: 10.1016/j.mcn.2019.103464] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 12/27/2019] [Accepted: 12/30/2019] [Indexed: 12/14/2022] Open
Abstract
Neurons are polarized cells, with dendrites and axons that require different complements of membrane proteins to fulfill their specialized functions. Membrane proteins are synthesized in the somatodendritic domain and delivered to their target membranes via long-range vesicle transport. Most anterograde vesicle transport is mediated by kinesin motors, but it is unclear how kinesins are targeted to axons or dendrites. Two main models have been proposed to explain kinesin selectivity. In the smart motor model, kinesin selectivity is conferred by a preference of the kinesin motor domain for specific subsets of microtubules. In the cargo steering model, kinesin selectivity is modulated by the vesicular cargo to which the motor is bound. We evaluate the evidence for both models and conclude that while the smart motor model may explain axonal selectivity, cargo steering is required for dendritic selectivity. Future work will determine the relative contributions of these models to polarized transport in living neurons.
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15
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Sleigh JN, Tosolini AP, Schiavo G. In Vivo Imaging of Anterograde and Retrograde Axonal Transport in Rodent Peripheral Nerves. Methods Mol Biol 2020; 2143:271-292. [PMID: 32524487 PMCID: PMC7116510 DOI: 10.1007/978-1-0716-0585-1_20] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Axonal transport, which is the process mediating the active shuttling of a variety cargoes from one end of an axon to the other, is essential for the development, function, and survival of neurons. Impairments in this dynamic process are linked to diverse nervous system diseases and advanced ageing. It is thus essential that we quantitatively study the kinetics of axonal transport to gain an improved understanding of neuropathology as well as the molecular and cellular mechanisms regulating cargo trafficking. One of the best ways to achieve this goal is by imaging individual, fluorescent cargoes in live systems and analyzing the kinetic properties of their progression along the axon. We have therefore developed an intravital technique to visualize different organelles, such as signaling endosomes and mitochondria, being actively transported in the axons of both motor and sensory neurons in live, anesthetized rodents. In this chapter, we provide step-by-step instructions on how to deliver specific organelle-targeting, fluorescent probes using several routes of administration to image individual cargoes being bidirectionally transported along axons within the exposed sciatic nerve. This method can provide detailed, physiologically relevant information on axonal transport, and is thus poised to elucidate mechanisms regulating this process in both health and disease.
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Affiliation(s)
- 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
| | - Andrew P Tosolini
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, University College London, London, UK
| | - 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, London, UK.
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