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Gallo G. The Axonal Actin Filament Cytoskeleton: Structure, Function, and Relevance to Injury and Degeneration. Mol Neurobiol 2024:10.1007/s12035-023-03879-7. [PMID: 38216856 DOI: 10.1007/s12035-023-03879-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 12/13/2023] [Indexed: 01/14/2024]
Abstract
Early investigations of the neuronal actin filament cytoskeleton gave rise to the notion that, although growth cones exhibit high levels of actin filaments, the axon shaft exhibits low levels of actin filaments. With the development of new tools and imaging techniques, the axonal actin filament cytoskeleton has undergone a renaissance and is now an active field of research. This article reviews the current state of knowledge about the actin cytoskeleton of the axon shaft. The best understood forms of actin filament organization along axons are axonal actin patches and a submembranous system of rings that endow the axon with protrusive competency and structural integrity, respectively. Additional forms of actin filament organization along the axon have also been described and their roles are being elucidated. Extracellular signals regulate the axonal actin filament cytoskeleton and our understanding of the signaling mechanisms involved is being elaborated. Finally, recent years have seen advances in our perspective on how the axonal actin cytoskeleton is impacted by, and contributes to, axon injury and degeneration. The work to date has opened new venues and future research will undoubtedly continue to provide a richer understanding of the axonal actin filament cytoskeleton.
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Affiliation(s)
- Gianluca Gallo
- Department of Neural Sciences, Shriners Pediatric Research Center, Lewis Katz School of Medicine at Temple University, 3500 North Broad St, Philadelphia, PA, 19140, USA.
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2
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Ermanoska B, Rodal AA. Non-muscle myosin II regulates presynaptic actin assemblies and neuronal mechanobiology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.10.566609. [PMID: 38014140 PMCID: PMC10680633 DOI: 10.1101/2023.11.10.566609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Neuromuscular junctions (NMJs) are evolutionarily ancient, specialized contacts between neurons and muscles. Axons and NMJs must endure mechanical strain through a lifetime of muscle contraction, making them vulnerable to aging and neurodegenerative conditions. However, cellular strategies for mitigating this mechanical stress remain unknown. In this study, we used Drosophila larval NMJs to investigate the role of actin and myosin (actomyosin)-mediated contractility in generating and responding to cellular forces at the neuron-muscle interface. We identified a new long-lived, low-turnover presynaptic actin core traversing the NMJ, which partly co-localizes with non-muscle myosin II (NMII). Neuronal RNAi of NMII induced disorganization of this core, suggesting that this structure might have contractile properties. Interestingly, neuronal RNAi of NMII also decreased NMII levels in the postsynaptic muscle proximal to neurons, suggesting that neuronal actomyosin rearrangements propagate their effects trans-synaptically. We also observed reduced Integrin levels upon NMII knockdown, indicating that neuronal actomyosin disruption triggers rearrangements of Integrin-mediated connections between neurons and surrounding muscle tissue. In summary, our study identifies a previously uncharacterized presynaptic actomyosin subpopulation that upholds the neuronal mechanical continuum, transmits signals to adjacent muscle tissue, and collaborates with Integrin receptors to govern the mechanobiology of the neuromuscular junction.
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DeVault L, Mateusiak C, Palucki J, Brent M, Milbrandt J, DiAntonio A. The response of Dual-Leucine Zipper Kinase (DLK) to nocodazole: evidence for a homeostatic cytoskeletal repair mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.06.561227. [PMID: 37873434 PMCID: PMC10592635 DOI: 10.1101/2023.10.06.561227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Genetic and pharmacological perturbation of the cytoskeleton enhances the regenerative potential of neurons. This response requires Dual-leucine Zipper Kinase (DLK), a neuronal stress sensor that is a central regulator of axon regeneration and degeneration. The damage and repair aspects of this response are reminiscent of other cellular homeostatic systems, suggesting that a cytoskeletal homeostatic response exists. In this study, we propose a framework for understanding DLK mediated neuronal cytoskeletal homeostasis. We demonstrate that a) low dose nocodazole treatment activates DLK signaling and b) DLK signaling mitigates the microtubule damage caused by the cytoskeletal perturbation. We also perform RNA-seq to discover a DLK-dependent transcriptional signature. This signature includes genes likely to attenuate DLK signaling while simultaneously inducing actin regulating genes and promoting actin-based morphological changes to the axon. These results are consistent with the model that cytoskeletal disruption in the neuron induces a DLK-dependent homeostatic mechanism, which we term the Cytoskeletal Stress Response (CSR) pathway.
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Groh J, Abdelwahab T, Kattimani Y, Hörner M, Loserth S, Gudi V, Adalbert R, Imdahl F, Saliba AE, Coleman M, Stangel M, Simons M, Martini R. Microglia-mediated demyelination protects against CD8 + T cell-driven axon degeneration in mice carrying PLP defects. Nat Commun 2023; 14:6911. [PMID: 37903797 PMCID: PMC10616105 DOI: 10.1038/s41467-023-42570-2] [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: 01/27/2023] [Accepted: 10/16/2023] [Indexed: 11/01/2023] Open
Abstract
Axon degeneration and functional decline in myelin diseases are often attributed to loss of myelin but their relation is not fully understood. Perturbed myelinating glia can instigate chronic neuroinflammation and contribute to demyelination and axonal damage. Here we study mice with distinct defects in the proteolipid protein 1 gene that develop axonal damage which is driven by cytotoxic T cells targeting myelinating oligodendrocytes. We show that persistent ensheathment with perturbed myelin poses a risk for axon degeneration, neuron loss, and behavioral decline. We demonstrate that CD8+ T cell-driven axonal damage is less likely to progress towards degeneration when axons are efficiently demyelinated by activated microglia. Mechanistically, we show that cytotoxic T cell effector molecules induce cytoskeletal alterations within myelinating glia and aberrant actomyosin constriction of axons at paranodal domains. Our study identifies detrimental axon-glia-immune interactions which promote neurodegeneration and possible therapeutic targets for disorders associated with myelin defects and neuroinflammation.
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Affiliation(s)
- Janos Groh
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany.
- Institute of Neuronal Cell Biology, Technical University Munich, Munich, Germany.
| | - Tassnim Abdelwahab
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Yogita Kattimani
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Michaela Hörner
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
- Department of Neurology, Section of Neurodegeneration, University Hospital Heidelberg, Heidelberg, Germany
| | - Silke Loserth
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany
| | - Viktoria Gudi
- Department of Neurology, Hannover Medical School, Hannover, Germany
| | - Robert Adalbert
- John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK
- Department of Anatomy, Histology and Embryology, University of Szeged, Szeged, Hungary
- Institute of Health Sciences Education, Faculty of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Fabian Imdahl
- Helmholtz Institute for RNA-based Infection Research, Helmholtz-Center for Infection Research, Würzburg, Germany
| | - Antoine-Emmanuel Saliba
- Helmholtz Institute for RNA-based Infection Research, Helmholtz-Center for Infection Research, Würzburg, Germany
- Institute of Molecular Infection Biology (IMIB), University of Würzburg, Würzburg, Germany
| | - Michael Coleman
- John van Geest Centre for Brain Repair, University of Cambridge, Cambridge, UK
| | - Martin Stangel
- Department of Neurology, Hannover Medical School, Hannover, Germany
- Translational Medicine, Novartis Institute of Biomedical Research, Basel, Switzerland
| | - Mikael Simons
- Institute of Neuronal Cell Biology, Technical University Munich, Munich, Germany
- German Center for Neurodegenerative Diseases, Munich, Germany
- Munich Cluster of Systems Neurology, Munich, Germany
| | - Rudolf Martini
- Department of Neurology, Section of Developmental Neurobiology, University Hospital Würzburg, Würzburg, Germany.
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Smith G, Sweeney ST, O’Kane CJ, Prokop A. How neurons maintain their axons long-term: an integrated view of axon biology and pathology. Front Neurosci 2023; 17:1236815. [PMID: 37564364 PMCID: PMC10410161 DOI: 10.3389/fnins.2023.1236815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 07/06/2023] [Indexed: 08/12/2023] Open
Abstract
Axons are processes of neurons, up to a metre long, that form the essential biological cables wiring nervous systems. They must survive, often far away from their cell bodies and up to a century in humans. This requires self-sufficient cell biology including structural proteins, organelles, and membrane trafficking, metabolic, signalling, translational, chaperone, and degradation machinery-all maintaining the homeostasis of energy, lipids, proteins, and signalling networks including reactive oxygen species and calcium. Axon maintenance also involves specialised cytoskeleton including the cortical actin-spectrin corset, and bundles of microtubules that provide the highways for motor-driven transport of components and organelles for virtually all the above-mentioned processes. Here, we aim to provide a conceptual overview of key aspects of axon biology and physiology, and the homeostatic networks they form. This homeostasis can be derailed, causing axonopathies through processes of ageing, trauma, poisoning, inflammation or genetic mutations. To illustrate which malfunctions of organelles or cell biological processes can lead to axonopathies, we focus on axonopathy-linked subcellular defects caused by genetic mutations. Based on these descriptions and backed up by our comprehensive data mining of genes linked to neural disorders, we describe the 'dependency cycle of local axon homeostasis' as an integrative model to explain why very different causes can trigger very similar axonopathies, providing new ideas that can drive the quest for strategies able to battle these devastating diseases.
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Affiliation(s)
- Gaynor Smith
- Cardiff University, School of Medicine, College of Biomedical and Life Sciences, Cardiff, United Kingdom
| | - Sean T. Sweeney
- Department of Biology, University of York and York Biomedical Research Institute, York, United Kingdom
| | - Cahir J. O’Kane
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Andreas Prokop
- Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, The University of Manchester, Manchester, United Kingdom
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Appeltshauser L, Linke J, Heil HS, Karus C, Schenk J, Hemmen K, Sommer C, Doppler K, Heinze KG. Super-resolution imaging pinpoints the periodic ultrastructure at the human node of Ranvier and its disruption in patients with polyneuropathy. Neurobiol Dis 2023; 182:106139. [PMID: 37146836 DOI: 10.1016/j.nbd.2023.106139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 05/07/2023] Open
Abstract
The node of Ranvier is the key element in saltatory conduction along myelinated axons, but its specific protein organization remains elusive in the human species. To shed light on nanoscale anatomy of the human node of Ranvier in health and disease, we assessed human nerve biopsies of patients with polyneuropathy by super-resolution fluorescence microscopy. We applied direct stochastic optical reconstruction microscopy (dSTORM) and supported our data by high-content confocal imaging combined with deep learning-based analysis. As a result, we revealed a ~ 190 nm periodic protein arrangement of cytoskeletal proteins and axoglial cell adhesion molecules in human peripheral nerves. In patients with polyneuropathy, periodic distances increased at the paranodal region of the node of Ranvier, both at the axonal cytoskeleton and at the axoglial junction. In-depth image analysis revealed a partial loss of proteins of the axoglial complex (Caspr-1, neurofascin-155) in combination with detachment from the cytoskeletal anchor protein ß2-spectrin. High content analysis showed that such paranodal disorganization occurred especially in acute and severe axonal neuropathy with ongoing Wallerian degeneration and related cytoskeletal damage. We provide nanoscale and protein-specific evidence for the prominent, but vulnerable role of the node of Ranvier for axonal integrity. Furthermore, we show that super-resolution imaging can identify, quantify and map elongated periodic protein distances and protein interaction in histopathological tissue samples. We thus introduce a promising tool for further translational applications of super resolution microscopy.
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Affiliation(s)
| | - Janis Linke
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany; Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Hannah S Heil
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany; Optical Cell Biology, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Christine Karus
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Joachim Schenk
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Katherina Hemmen
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Claudia Sommer
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany
| | - Kathrin Doppler
- Department of Neurology, University Hospital Würzburg, Würzburg, Germany.
| | - Katrin G Heinze
- Rudolf Virchow Center, Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany.
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Abstract
Recently, researches have revealed the key roles of the cytoskeleton in the occurrence and development of multiple diseases, suggesting that targeting the cytoskeleton is a viable approach for treating numerous refractory diseases. The cytoskeleton is a highly structured and complex network composed of actin filaments, microtubules, and intermediate filaments. In normal cells, these three cytoskeleton components are highly integrated and coordinated. However, the cytoskeleton undergoes drastic remodeling in cytoskeleton-related diseases, causing changes in cell polarity, affecting the cell cycle, leading to senescent diseases, and influencing cell migration to accelerate cancer metastasis. Additionally, mutations or abnormalities in cytoskeletal proteins and their related proteins are closely associated with several congenital diseases. Therefore, this review summarizes the roles of the cytoskeleton in cytoskeleton-related diseases as well as its potential roles in disease treatment to provide insights regarding the physiological functions and pathological roles of the cytoskeleton.
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Pan X, Li J, Li W, Wang H, Durisic N, Li Z, Feng Y, Liu Y, Zhao CX, Wang T. Axons-on-a-chip for mimicking non-disruptive diffuse axonal injury underlying traumatic brain injury. LAB ON A CHIP 2022; 22:4541-4555. [PMID: 36318066 DOI: 10.1039/d2lc00730d] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Diffuse axonal injury (DAI) is the most severe pathological feature of traumatic brain injury (TBI). However, how primary axonal injury is induced by transient mechanical impacts remains unknown, mainly due to the low temporal and spatial resolution of medical imaging approaches. Here we established an axon-on-a-chip (AoC) model for mimicking DAI and monitoring instant cellular responses. Integrating computational fluid dynamics and microfluidic techniques, DAI was induced by injecting a precisely controlled micro-flux in the transverse direction. The clear correlation between the flow speed of injecting flux and the severity of DAI was elucidated. We next used the AoC to investigate the instant intracellular responses underlying DAI and found that the dynamic formation of focal axonal swellings (FAS) accompanied by Ca2+ surge occurs during the flux. Surprisingly, periodic axonal cytoskeleton disruption also occurs rapidly after the flux. These instant injury responses are spatially restricted to the fluxed axon, not affecting the overall viability of the neuron in the acute stage. Compatible with high-resolution live microscopy, the AoC provides a versatile system to identify early mechanisms underlying DAI, offering a platform for screening effective treatments to alleviate TBI.
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Affiliation(s)
- Xiaorong Pan
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| | - Jie Li
- Division of Chemistry and Physical Biology, School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Wei Li
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Haofei Wang
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Nela Durisic
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Zhenyu Li
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| | - Yu Feng
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
| | - Yifan Liu
- Division of Chemistry and Physical Biology, School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Chun-Xia Zhao
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, QLD 4072, Australia
- School of Chemical Engineering and Advanced Materials, The University of Adelaide, Adelaide, SA 5005, Australia.
| | - Tong Wang
- The Brain Center, School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
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9
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Dorrego-Rivas A, Ezan J, Moreau MM, Poirault-Chassac S, Aubailly N, De Neve J, Blanchard C, Castets F, Fréal A, Battefeld A, Sans N, Montcouquiol M. The core PCP protein Prickle2 regulates axon number and AIS maturation by binding to AnkG and modulating microtubule bundling. SCIENCE ADVANCES 2022; 8:eabo6333. [PMID: 36083912 PMCID: PMC9462691 DOI: 10.1126/sciadv.abo6333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 07/25/2022] [Indexed: 06/15/2023]
Abstract
Core planar cell polarity (PCP) genes, which are involved in various neurodevelopmental disorders such as neural tube closure, epilepsy, and autism spectrum disorder, have poorly defined molecular signatures in neurons, mostly synapse-centric. Here, we show that the core PCP protein Prickle-like protein 2 (Prickle2) controls neuronal polarity and is a previously unidentified member of the axonal initial segment (AIS) proteome. We found that Prickle2 is present and colocalizes with AnkG480, the AIS master organizer, in the earliest stages of axonal specification and AIS formation. Furthermore, by binding to and regulating AnkG480, Prickle2 modulates its ability to bundle microtubules, a crucial mechanism for establishing neuronal polarity and AIS formation. Prickle2 depletion alters cytoskeleton organization, and Prickle2 levels determine both axon number and AIS maturation. Last, early Prickle2 depletion produces impaired action potential firing.
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Affiliation(s)
- Ana Dorrego-Rivas
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33077 Bordeaux, France
- Corresponding author.
| | - Jerome Ezan
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33077 Bordeaux, France
| | - Maïté M Moreau
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33077 Bordeaux, France
| | | | | | - Julie De Neve
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33077 Bordeaux, France
| | | | - Francis Castets
- Aix-Marseille Université, CNRS, Institut de Biologie du Développement de Marseille, UMR 7288, Case 907, 13288 Marseille Cedex 09, France
| | - Amélie Fréal
- Department of Functional Genomics, Vrije Universiteit (VU), Amsterdam, Netherlands
| | - Arne Battefeld
- Univ. Bordeaux, CNRS, IMN, UMR 5293, F-33000 Bordeaux, France
| | - Nathalie Sans
- Univ. Bordeaux, INSERM, Magendie, U1215, F-33077 Bordeaux, France
- Corresponding author.
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Cytoskeletal assembly in axonal outgrowth and regeneration analyzed on the nanoscale. Sci Rep 2022; 12:14387. [PMID: 35999340 PMCID: PMC9399097 DOI: 10.1038/s41598-022-18562-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 08/16/2022] [Indexed: 11/08/2022] Open
Abstract
The axonal cytoskeleton is organized in a highly periodic structure, the membrane-associated periodic skeleton (MPS), which is essential to maintain the structure and function of the axon. Here, we use stimulated emission depletion microscopy of primary rat cortical neurons in microfluidic chambers to analyze the temporal and spatial sequence of MPS formation at the distal end of growing axons and during regeneration after axotomy. We demonstrate that the MPS does not extend continuously into the growing axon but develops from patches of periodic βII-spectrin arrangements that grow and coalesce into a continuous scaffold. We estimate that the underlying sequence of assembly, elongation, and subsequent coalescence of periodic βII-spectrin patches takes around 15 h. Strikingly, we find that development of the MPS occurs faster in regenerating axons after axotomy and note marked differences in the morphology of the growth cone and adjacent axonal regions between regenerating and unlesioned axons. Moreover, we find that inhibition of the spectrin-cleaving enzyme calpain accelerates MPS formation in regenerating axons and increases the number of regenerating axons after axotomy. Taken together, we provide here a detailed nanoscale analysis of MPS development in growing axons.
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11
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Zhou R, Han B, Nowak R, Lu Y, Heller E, Xia C, Chishti AH, Fowler VM, Zhuang X. Proteomic and functional analyses of the periodic membrane skeleton in neurons. Nat Commun 2022; 13:3196. [PMID: 35680881 PMCID: PMC9184744 DOI: 10.1038/s41467-022-30720-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 05/09/2022] [Indexed: 12/29/2022] Open
Abstract
Actin, spectrin, and associated molecules form a membrane-associated periodic skeleton (MPS) in neurons. The molecular composition and functions of the MPS remain incompletely understood. Here, using co-immunoprecipitation and mass spectrometry, we identified hundreds of potential candidate MPS-interacting proteins that span diverse functional categories. We examined representative proteins in several of these categories using super-resolution imaging, including previously unknown MPS structural components, as well as motor proteins, cell adhesion molecules, ion channels, and signaling proteins, and observed periodic distributions characteristic of the MPS along the neurites for ~20 proteins. Genetic perturbations of the MPS and its interacting proteins further suggested functional roles of the MPS in axon-axon and axon-dendrite interactions and in axon diameter regulation, and implicated the involvement of MPS interactions with cell adhesion molecules and non-muscle myosin in these roles. These results provide insights into the interactome of the MPS and suggest previously unknown functions of the MPS in neurons.
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Affiliation(s)
- Ruobo Zhou
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry, The Pennsylvania State University, University Park, PA, 16802, USA.
| | - Boran Han
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Roberta Nowak
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
| | - Yunzhe Lu
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Evan Heller
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Chenglong Xia
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - Athar H Chishti
- Department of Developmental, Molecular, and Chemical Biology, Tufts University School of Medicine, Boston, MA, 02111, USA
| | - Velia M Fowler
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, 92307, USA
- Department of Biological Sciences, The University of Delaware, Newark, DE, 19716, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02138, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA.
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12
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Martínez GF, Fagetti J, Vierci G, Brauer MM, Unsain N, Richeri A. Extracellular matrix stiffness negatively affects axon elongation, growth cone area and F-actin levels in a collagen type I 3D culture. J Tissue Eng Regen Med 2021; 16:151-162. [PMID: 34816618 DOI: 10.1002/term.3269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 11/10/2021] [Accepted: 11/17/2021] [Indexed: 12/11/2022]
Abstract
Three dimensional (3D) in vitro neuronal cultures can better reproduce physiologically relevant phenotypes compared to 2D-cultures, because in vivo neurons reside in a 3D microenvironment. Interest in neuronal 3D cultures is emerging, with special attention to the mechanical forces that regulate axon elongation and sprouting in three dimensions. Type I collagen (Col-I) is a native substrate since it is present in the extracellular matrix and hence emulates an in vivo environment to study axon growth. The impact of its mechanical properties needs to be further investigated. Here, we generated Col-I 3D matrices of different mechanical stiffness and evaluated axon growth in three dimensions. Superior cervical ganglion (SCG) explants from neonatal rats were cultured in soft and stiff Col-I 3D matrices and neurite outgrowth was assessed by measuring: maximum neuritic extent; neuritic halo area and fasciculation. Axonal cytoskeletal proteins were examined. Axon elongation in stiff Col-I 3D matrices was reduced (31%) following 24 h in culture compared to soft matrices. In stiff matrices, neurites fasciculated and formed less dense halos. Consistently, almost no F-actin rich growth cones were recognized, and F-actin staining was strongly reduced in the axonal compartment. This study shows that stiffness negatively affects 3D neurite outgrowth and adds insights on the cytoskeletal responses upon mechanic interactions of axons with a 3D environment. Our data will serve to facilitate the development of model systems that are mechanically well-behaved but still mimic key physiologic properties observed in vivo.
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Affiliation(s)
- Gaby F Martínez
- Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay.,Laboratorio de Biología Celular, Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Jimena Fagetti
- Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Gabriela Vierci
- Laboratorio de Biología Celular, Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - M Mónica Brauer
- Laboratorio de Biología Celular, Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
| | - Nicolás Unsain
- Laboratorio de Neurobiología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba (UNC), Córdoba, Argentina
| | - Analía Richeri
- Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay.,Laboratorio de Biología Celular, Departamento de Neurofarmacología Experimental, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE), Montevideo, Uruguay
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13
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He Y, Duan L, Wu H, Chen S, Lu T, Li T, He Y. Integrated Transcriptome Analysis Reveals the Impact of Photodynamic Therapy on Cerebrovascular Endothelial Cells. Front Oncol 2021; 11:731414. [PMID: 34881175 PMCID: PMC8645902 DOI: 10.3389/fonc.2021.731414] [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: 06/27/2021] [Accepted: 11/03/2021] [Indexed: 01/10/2023] Open
Abstract
Blood vessels in the brain tissue form a compact vessel structure and play an essential role in maintaining the homeostasis of the neurovascular system. The low dosage of photodynamic intervention (PDT) significantly affects the expression of cellular biomarkers. To understand the impact of photodynamic interventions on cerebrovascular endothelial cells, we evaluated the dosage-dependent impact of porfimer sodium-mediated PDT on B.END3 cells using flow cytometer, comet assay, RNA sequencing, and bioinformatics analysis. To examine whether PDT can induce disorder of intracellular organelles, we did not observe any significance damage of DNA and cellular skeleton. Moreover, expression levels of cellular transporters-related genes were significantly altered, implying the drawbacks of PDT on cerebrovascular functions. To address the potential molecular mechanisms of these phenotypes, RNA sequencing and bioinformatics analysis were employed to identify critical genes and pathways among these processes. The gene ontology (GO) analysis and protein-protein interaction (PPI) identified 15 hub genes, highly associated with cellular mitosis process (CDK1, CDC20, MCM5, MCM7, MCM4, CCNA2, AURKB, KIF2C, ESPL1, BUB1B) and DNA replication (POLE2, PLOE, CDC45, CDC6). Gene set enrichment analysis (GSEA) reveals that TNF-α/NF-κB and KRAS pathways may play a critical role in regulating expression levels of transporter-related genes. To further perform qRT-PCR assays, we find that TNF-α/NF-κB and KRAS pathways were substantially up-regulated, consistent with GSEA analysis. The current findings suggested that a low dosage of PDT intervention may be detrimental to the homeostasis of blood-brain barrier (BBB) by inducing the inflammatory response and affecting the expression of surface biomarkers.
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Affiliation(s)
- Yanyan He
- Department of Cerebrovascular Disease, Henan Provincial People’s Hospital, Zhengzhou University People’s Hospital, Henan International Joint Laboratory of Cerebrovascular Disease, Zhengzhou, China
| | - Lin Duan
- Department of Cerebrovascular Disease, Henan Provincial People’s Hospital, Zhengzhou University People’s Hospital, Henan International Joint Laboratory of Cerebrovascular Disease, Zhengzhou, China
| | - Haigang Wu
- School of Life Sciences, Henan University, Kaifeng, China
| | - Song Chen
- Translational Research Institute, Henan Provincial People’s Hospital, Zhengzhou University, Academy of Medical Science, Zhengzhou, China
| | - Taoyuan Lu
- Department of Cerebrovascular Disease, Henan Provincial People’s Hospital, Zhengzhou University People’s Hospital, Henan International Joint Laboratory of Cerebrovascular Disease, Zhengzhou, China
| | - Tianxiao Li
- Department of Cerebrovascular Disease, Henan Provincial People’s Hospital, Zhengzhou University People’s Hospital, Henan International Joint Laboratory of Cerebrovascular Disease, Zhengzhou, China
| | - Yingkun He
- Department of Cerebrovascular Disease, Henan Provincial People’s Hospital, Zhengzhou University People’s Hospital, Henan International Joint Laboratory of Cerebrovascular Disease, Zhengzhou, China
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14
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Yong Y, Hunter-Chang S, Stepanova E, Deppmann C. Axonal spheroids in neurodegeneration. Mol Cell Neurosci 2021; 117:103679. [PMID: 34678457 PMCID: PMC8742877 DOI: 10.1016/j.mcn.2021.103679] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/12/2021] [Accepted: 10/15/2021] [Indexed: 10/20/2022] Open
Abstract
Axonal spheroids are bubble-like biological features that form on most degenerating axons, yet little is known about their influence on degenerative processes. Their formation and growth has been observed in response to various degenerative triggers such as injury, oxidative stress, inflammatory factors, and neurotoxic molecules. They often contain cytoskeletal elements and organelles, and, depending on the pathological insult, can colocalize with disease-related proteins such as amyloid precursor protein (APP), ubiquitin, and motor proteins. Initial formation of axonal spheroids depends on the disruption of axonal and membrane tension governed by cytoskeleton structure and calcium levels. Shortly after spheroid formation, the engulfment signal phosphatidylserine (PS) is exposed on the outer leaflet of spheroid plasma membrane, suggesting an important role for axonal spheroids in phagocytosis and debris clearance during degeneration. Spheroids can grow until they rupture, allowing pro-degenerative factors to exit the axon into extracellular space and accelerating neurodegeneration. Though much remains to be discovered in this area, axonal spheroid research promises to lend insight into the etiologies of neurodegenerative disease, and may be an important target for therapeutic intervention. This review summarizes over 100 years of work, describing what is known about axonal spheroid structure, regulation and function.
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Affiliation(s)
- Yu Yong
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Sarah Hunter-Chang
- Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22903, USA
| | - Ekaterina Stepanova
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA
| | - Christopher Deppmann
- Department of Biology, University of Virginia, Charlottesville, VA 22903, USA; Neuroscience Graduate Program, University of Virginia, Charlottesville, VA 22903, USA.
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15
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Costa AR, Sousa MM. The role of the membrane-associated periodic skeleton in axons. Cell Mol Life Sci 2021; 78:5371-5379. [PMID: 34085116 PMCID: PMC11071922 DOI: 10.1007/s00018-021-03867-x] [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: 02/06/2021] [Revised: 05/14/2021] [Accepted: 05/27/2021] [Indexed: 11/24/2022]
Abstract
The identification of the membrane periodic skeleton (MPS), composed of a periodic lattice of actin rings interconnected by spectrin tetramers, was enabled by the development of super-resolution microscopy, and brought a new exciting perspective to our view of neuronal biology. This exquisite cytoskeleton arrangement plays an important role on mechanisms regulating neuronal (dys)function. The MPS was initially thought to provide mainly for axonal mechanical stability. Since its discovery, the importance of the MPS in multiple aspects of neuronal biology has, however, emerged. These comprise its capacity to act as a signaling platform, regulate axon diameter-with important consequences on the efficiency of axonal transport and electrophysiological properties- participate in the assembly and function of the axon initial segment, and control axon microtubule stability. Recently, MPS disassembly has also surfaced as an early player in the course of axon degeneration. Here, we will discuss the current knowledge on the role of the MPS in axonal physiology and disease.
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Affiliation(s)
- Ana Rita Costa
- Nerve Regeneration Group, IBMC- Instituto de Biologia Molecular e Celular and i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal
| | - Monica Mendes Sousa
- Nerve Regeneration Group, IBMC- Instituto de Biologia Molecular e Celular and i3S- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135, Porto, Portugal.
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16
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Pan X, Zhou Y, Hotulainen P, Meunier FA, Wang T. The axonal radial contractility: Structural basis underlying a new form of neural plasticity. Bioessays 2021; 43:e2100033. [PMID: 34145916 DOI: 10.1002/bies.202100033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 05/27/2021] [Accepted: 06/02/2021] [Indexed: 12/25/2022]
Abstract
Axons are the longest cellular structure reaching over a meter in the case of human motor axons. They have a relatively small diameter and contain several cytoskeletal elements that mediate both material and information exchange within neurons. Recently, a novel type of axonal plasticity, termed axonal radial contractility, has been unveiled. It is represented by dynamic and transient diameter changes of the axon shaft to accommodate the passages of large organelles. Mechanisms underpinning this plasticity are not fully understood. Here, we first summarised recent evidence of the functional relevance for axon radial contractility, then discussed the underlying structural basis, reviewing nanoscopic evidence of the subtle changes. Two models are proposed to explain how actomyosin rings are organised. Possible roles of non-muscle myosin II (NM-II) in axon degeneration are discussed. Finally, we discuss the concept of periodic functional nanodomains, which could sense extracellular cues and coordinate the axonal responses. Also see the video abstract here: https://youtu.be/ojCnrJ8RCRc.
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Affiliation(s)
- Xiaorong Pan
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
| | - Yimin Zhou
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
| | - Pirta Hotulainen
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Tong Wang
- Center for Brain Science, School of Life Science and Technology, Shanghaitech University, Shanghai, China
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17
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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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18
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Miazek A, Zalas M, Skrzymowska J, Bogin BA, Grzymajło K, Goszczynski TM, Levine ZA, Morrow JS, Stankewich MC. Age-dependent ataxia and neurodegeneration caused by an αII spectrin mutation with impaired regulation of its calpain sensitivity. Sci Rep 2021; 11:7312. [PMID: 33790315 PMCID: PMC8012654 DOI: 10.1038/s41598-021-86470-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 03/15/2021] [Indexed: 12/15/2022] Open
Abstract
The neuronal membrane-associated periodic spectrin skeleton (MPS) contributes to neuronal development, remodeling, and organization. Post-translational modifications impinge on spectrin, the major component of the MPS, but their role remains poorly understood. One modification targeting spectrin is cleavage by calpains, a family of calcium-activated proteases. Spectrin cleavage is regulated by activated calpain, but also by the calcium-dependent binding of calmodulin (CaM) to spectrin. The physiologic significance of this balance between calpain activation and substrate-level regulation of spectrin cleavage is unknown. We report a strain of C57BL/6J mice harboring a single αII spectrin point mutation (Sptan1 c.3293G > A:p.R1098Q) with reduced CaM affinity and intrinsically enhanced sensitivity to calpain proteolysis. Homozygotes are embryonic lethal. Newborn heterozygotes of either gender appear normal, but soon develop a progressive ataxia characterized biochemically by accelerated calpain-mediated spectrin cleavage and morphologically by disruption of axonal and dendritic integrity and global neurodegeneration. Molecular modeling predicts unconstrained exposure of the mutant spectrin's calpain-cleavage site. These results reveal the critical importance of substrate-level regulation of spectrin cleavage for the maintenance of neuronal integrity. Given that excessive activation of calpain proteases is a common feature of neurodegenerative disease and traumatic encephalopathy, we propose that damage to the spectrin MPS may contribute to the neuropathology of many disorders.
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Affiliation(s)
- Arkadiusz Miazek
- Department of Tumor Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wrocław, Poland
- Department of Biochemistry and Molecular Biology, Wroclaw University of Environmental and Life Sciences, Norwida 31, 50-375, Wrocław, Poland
| | - Michał Zalas
- Department of Tumor Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wrocław, Poland
| | - Joanna Skrzymowska
- Department of Tumor Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wrocław, Poland
| | - Bryan A Bogin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
| | - Krzysztof Grzymajło
- Department of Biochemistry and Molecular Biology, Wroclaw University of Environmental and Life Sciences, Norwida 31, 50-375, Wrocław, Poland
| | - Tomasz M Goszczynski
- Department of Tumor Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114, Wrocław, Poland
| | - Zachary A Levine
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
- Department of Pathology, Yale University School of Medicine, 310 Cedar Street, LH108, New Haven, CT, 06520, USA
| | - Jon S Morrow
- Department of Pathology, Yale University School of Medicine, 310 Cedar Street, LH108, New Haven, CT, 06520, USA.
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT, USA.
| | - Michael C Stankewich
- Department of Pathology, Yale University School of Medicine, 310 Cedar Street, LH108, New Haven, CT, 06520, USA.
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19
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Beijer D, Baets J. The expanding genetic landscape of hereditary motor neuropathies. Brain 2021; 143:3540-3563. [PMID: 33210134 DOI: 10.1093/brain/awaa311] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/15/2020] [Accepted: 07/27/2020] [Indexed: 12/12/2022] Open
Abstract
Hereditary motor neuropathies are clinically and genetically diverse disorders characterized by length-dependent axonal degeneration of lower motor neurons. Although currently as many as 26 causal genes are known, there is considerable missing heritability compared to other inherited neuropathies such as Charcot-Marie-Tooth disease. Intriguingly, this genetic landscape spans a discrete number of key biological processes within the peripheral nerve. Also, in terms of underlying pathophysiology, hereditary motor neuropathies show striking overlap with several other neuromuscular and neurological disorders. In this review, we provide a current overview of the genetic spectrum of hereditary motor neuropathies highlighting recent reports of novel genes and mutations or recent discoveries in the underlying disease mechanisms. In addition, we link hereditary motor neuropathies with various related disorders by addressing the main affected pathways of disease divided into five major processes: axonal transport, tRNA aminoacylation, RNA metabolism and DNA integrity, ion channels and transporters and endoplasmic reticulum.
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Affiliation(s)
- Danique Beijer
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium
| | - Jonathan Baets
- Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Belgium.,Laboratory of Neuromuscular Pathology, Institute Born-Bunge, University of Antwerp, Belgium.,Neuromuscular Reference Centre, Department of Neurology, Antwerp University Hospital, Belgium
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20
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Hrstka SCL, Ankam S, Agac B, Klein JP, Moore RA, Narapureddy B, Schneider I, Hrstka RF, Dasari S, Staff NP. Proteomic analysis of human iPSC-derived sensory neurons implicates cell stress and microtubule dynamics dysfunction in bortezomib-induced peripheral neurotoxicity. Exp Neurol 2021; 335:113520. [PMID: 33129842 PMCID: PMC7750199 DOI: 10.1016/j.expneurol.2020.113520] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/22/2020] [Accepted: 10/25/2020] [Indexed: 12/26/2022]
Abstract
The neurotoxic effects of the chemotherapeutic agent bortezomib on dorsal root ganglia sensory neurons are well documented, yet the mechanistic underpinnings that govern these cellular processes remain incompletely understood. In this study, system-wide proteomic changes were identified in human induced pluripotent stem cell-derived sensory neurons (iSNs) exposed to a clinically relevant dose of bortezomib. Label-free mass spectrometry facilitated the identification of approximately 2800 iSN proteins that exhibited differential levels in the setting of bortezomib. A significant proportion of these proteins affect the cellular processes of microtubule dynamics, cytoskeletal and cytoplasmic organization, and molecular transport, and pathway analysis revealed an enrichment of proteins in signaling pathways attributable to the unfolded protein response and the integrated stress response. Alterations in microtubule-associated proteins suggest a multifaceted relationship exists between bortezomib-induced proteotoxicity and microtubule cytoskeletal architecture, and MAP2 was prioritized as a topmost influential candidate. We observed a significant reduction in the overall levels of MAP2c in somata without discernable changes in neurites. As MAP2 is known to affect cellular processes including axonogenesis, neurite extension and branching, and neurite morphology, its altered levels are suggestive of a prominent role in bortezomib-induced neurotoxicity.
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Affiliation(s)
- Sybil C L Hrstka
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Soneela Ankam
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Busranur Agac
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Jon P Klein
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Raymond A Moore
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, United States of America
| | - Bhavya Narapureddy
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Isabella Schneider
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Ronald F Hrstka
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America
| | - Surendra Dasari
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN, United States of America
| | - Nathan P Staff
- Department of Neurology, Mayo Clinic, Rochester, MN, United States of America.
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21
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Costa AR, Sousa MM. Non-Muscle Myosin II in Axonal Cell Biology: From the Growth Cone to the Axon Initial Segment. Cells 2020; 9:cells9091961. [PMID: 32858875 PMCID: PMC7563147 DOI: 10.3390/cells9091961] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 08/21/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022] Open
Abstract
By binding to actin filaments, non-muscle myosin II (NMII) generates actomyosin networks that hold unique contractile properties. Their dynamic nature is essential for neuronal biology including the establishment of polarity, growth cone formation and motility, axon growth during development (and axon regeneration in the adult), radial and longitudinal axonal tension, and synapse formation and function. In this review, we discuss the current knowledge on the spatial distribution and function of the actomyosin cytoskeleton in different axonal compartments. We highlight some of the apparent contradictions and open questions in the field, including the role of NMII in the regulation of axon growth and regeneration, the possibility that NMII structural arrangement along the axon shaft may control both radial and longitudinal contractility, and the mechanism and functional purpose underlying NMII enrichment in the axon initial segment. With the advances in live cell imaging and super resolution microscopy, it is expected that in the near future the spatial distribution of NMII in the axon, and the mechanisms by which it participates in axonal biology will be further untangled.
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22
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Neuronal activity remodels the F-actin based submembrane lattice in dendrites but not axons of hippocampal neurons. Sci Rep 2020; 10:11960. [PMID: 32686703 PMCID: PMC7371643 DOI: 10.1038/s41598-020-68180-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 06/17/2020] [Indexed: 12/29/2022] Open
Abstract
The nanoscale organization of the F-actin cytoskeleton in neurons comprises membrane-associated periodical rings, bundles, and longitudinal fibers. The F-actin rings have been observed predominantly in axons but only sporadically in dendrites, where fluorescence nanoscopy reveals various patterns of F-actin arranged in mixed patches. These complex dendritic F-actin patterns pose a challenge for investigating quantitatively their regulatory mechanisms. We developed here a weakly supervised deep learning segmentation approach of fluorescence nanoscopy images of F-actin in cultured hippocampal neurons. This approach enabled the quantitative assessment of F-actin remodeling, revealing the disappearance of the rings during neuronal activity in dendrites, but not in axons. The dendritic F-actin cytoskeleton of activated neurons remodeled into longitudinal fibers. We show that this activity-dependent remodeling involves \documentclass[12pt]{minimal}
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\begin{document}$$\text {Ca}^{2+}$$\end{document}Ca2+ and NMDA receptor-dependent mechanisms. This highly dynamic restructuring of dendritic F-actin based submembrane lattice into longitudinal fibers may serve to support activity-dependent membrane remodeling, protein trafficking and neuronal plasticity.
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23
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Wang T, Li W, Martin S, Papadopulos A, Joensuu M, Liu C, Jiang A, Shamsollahi G, Amor R, Lanoue V, Padmanabhan P, Meunier FA. Radial contractility of actomyosin rings facilitates axonal trafficking and structural stability. J Cell Biol 2020; 219:e201902001. [PMID: 32182623 PMCID: PMC7199852 DOI: 10.1083/jcb.201902001] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 09/17/2019] [Accepted: 02/10/2020] [Indexed: 02/07/2023] Open
Abstract
Most mammalian neurons have a narrow axon, which constrains the passage of large cargoes such as autophagosomes that can be larger than the axon diameter. Radial axonal expansion must therefore occur to ensure efficient axonal trafficking. In this study, we reveal that the speed of various large cargoes undergoing axonal transport is significantly slower than that of small ones and that the transit of diverse-sized cargoes causes an acute, albeit transient, axonal radial expansion, which is immediately restored by constitutive axonal contractility. Using live super-resolution microscopy, we demonstrate that actomyosin-II controls axonal radial contractility and local expansion, and that NM-II filaments associate with periodic F-actin rings via their head domains. Pharmacological inhibition of NM-II activity significantly increases axon diameter by detaching the NM-II from F-actin and impacts the trafficking speed, directionality, and overall efficiency of long-range retrograde trafficking. Consequently, prolonged NM-II inactivation leads to disruption of periodic actin rings and formation of focal axonal swellings, a hallmark of axonal degeneration.
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Affiliation(s)
- Tong Wang
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- The Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Wei Li
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- The Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Sally Martin
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
- The Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, Brisbane, Australia
| | - Andreas Papadopulos
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Chunxia Liu
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Anmin Jiang
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Golnoosh Shamsollahi
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Rumelo Amor
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Vanessa Lanoue
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Pranesh Padmanabhan
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
| | - Frédéric A. Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Australia
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24
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Martínez GF, Gazal NG, Quassollo G, Szalai AM, Cid-Pellitero ED, Durcan TM, Fon EA, Bisbal M, Stefani FD, Unsain N. Quantitative expansion microscopy for the characterization of the spectrin periodic skeleton of axons using fluorescence microscopy. Sci Rep 2020; 10:2917. [PMID: 32076054 PMCID: PMC7031372 DOI: 10.1038/s41598-020-59856-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 01/07/2020] [Indexed: 01/14/2023] Open
Abstract
Fluorescent nanoscopy approaches have been used to characterize the periodic organization of actin, spectrin and associated proteins in neuronal axons and dendrites. This membrane-associated periodic skeleton (MPS) is conserved across animals, suggesting it is a fundamental component of neuronal extensions. The nanoscale architecture of the arrangement (190 nm) is below the resolution limit of conventional fluorescent microscopy. Fluorescent nanoscopy, on the other hand, requires costly equipment and special analysis routines, which remain inaccessible to most research groups. This report aims to resolve this issue by using protein-retention expansion microscopy (pro-ExM) to reveal the MPS of axons. ExM uses reagents and equipment that are readily accessible in most neurobiology laboratories. We first explore means to accurately estimate the expansion factors of protein structures within cells. We then describe the protocol that produces an expanded specimen that can be examined with any fluorescent microscopy allowing quantitative nanoscale characterization of the MPS. We validate ExM results by direct comparison to stimulated emission depletion (STED) nanoscopy. We conclude that ExM facilitates three-dimensional, multicolor and quantitative characterization of the MPS using accessible reagents and conventional fluorescent microscopes.
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Affiliation(s)
- Gaby F Martínez
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Nahir G Gazal
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Gonzalo Quassollo
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Alan M Szalai
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Esther Del Cid-Pellitero
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Thomas M Durcan
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Edward A Fon
- McGill Parkinson Program, Neurodegenerative Diseases Group, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Mariano Bisbal
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina
- Instituto Universitario Ciencias Biomédicas de Córdoba (IUCBC), Córdoba, Argentina
| | - Fernando D Stefani
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Nicolas Unsain
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Córdoba, Córdoba, Argentina.
- Instituto Universitario Ciencias Biomédicas de Córdoba (IUCBC), Córdoba, Argentina.
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25
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Lorenzo DN. Cargo hold and delivery: Ankyrins, spectrins, and their functional patterning of neurons. Cytoskeleton (Hoboken) 2020; 77:129-148. [PMID: 32034889 DOI: 10.1002/cm.21602] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 01/12/2023]
Abstract
The highly polarized, typically very long, and nonmitotic nature of neurons present them with unique challenges in the maintenance of their homeostasis. This architectural complexity serves a rich and tightly controlled set of functions that enables their fast communication with neighboring cells and endows them with exquisite plasticity. The submembrane neuronal cytoskeleton occupies a pivotal position in orchestrating the structural patterning that determines local and long-range subcellular specialization, membrane dynamics, and a wide range of signaling events. At its center is the partnership between ankyrins and spectrins, which self-assemble with both remarkable long-range regularity and micro- and nanoscale specificity to precisely position and stabilize cell adhesion molecules, membrane transporters, ion channels, and other cytoskeletal proteins. To accomplish these generally conserved, but often functionally divergent and spatially diverse, roles these partners use a combinatorial program of a couple of dozens interacting family members, whose code is not fully unraveled. In a departure from their scaffolding roles, ankyrins and spectrins also enable the delivery of material to the plasma membrane by facilitating intracellular transport. Thus, it is unsurprising that deficits in ankyrins and spectrins underlie several neurodevelopmental, neurodegenerative, and psychiatric disorders. Here, I summarize key aspects of the biology of spectrins and ankyrins in the mammalian neuron and provide a snapshot of the latest advances in decoding their roles in the nervous system.
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Affiliation(s)
- Damaris N Lorenzo
- Department of Cell Biology and Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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26
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Vassilopoulos S, Gibaud S, Jimenez A, Caillol G, Leterrier C. Ultrastructure of the axonal periodic scaffold reveals a braid-like organization of actin rings. Nat Commun 2019; 10:5803. [PMID: 31862971 PMCID: PMC6925202 DOI: 10.1038/s41467-019-13835-6] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 11/27/2019] [Indexed: 12/31/2022] Open
Abstract
Recent super-resolution microscopy studies have unveiled a periodic scaffold of actin rings regularly spaced by spectrins under the plasma membrane of axons. However, ultrastructural details are unknown, limiting a molecular and mechanistic understanding of these enigmatic structures. Here, we combine platinum-replica electron and optical super-resolution microscopy to investigate the cortical cytoskeleton of axons at the ultrastructural level. Immunogold labeling and correlative super-resolution/electron microscopy allow us to unambiguously resolve actin rings as braids made of two long, intertwined actin filaments connected by a dense mesh of aligned spectrins. This molecular arrangement contrasts with the currently assumed model of actin rings made of short, capped actin filaments. Along the proximal axon, we resolved the presence of phospho-myosin light chain and the scaffold connection with microtubules via ankyrin G. We propose that braided rings explain the observed stability of the actin-spectrin scaffold and ultimately participate in preserving the axon integrity.
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Affiliation(s)
- Stéphane Vassilopoulos
- Sorbonne Université, INSERM, Institute of Myology, Centre of Research in Myology, UMRS 974, Paris, France.
| | - Solène Gibaud
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, Marseille, France
| | - Angélique Jimenez
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, Marseille, France
| | - Ghislaine Caillol
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto, Marseille, France
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27
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Wang G, Simon DJ, Wu Z, Belsky DM, Heller E, O'Rourke MK, Hertz NT, Molina H, Zhong G, Tessier-Lavigne M, Zhuang X. Structural plasticity of actin-spectrin membrane skeleton and functional role of actin and spectrin in axon degeneration. eLife 2019; 8:e38730. [PMID: 31042147 PMCID: PMC6494423 DOI: 10.7554/elife.38730] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 03/30/2019] [Indexed: 01/08/2023] Open
Abstract
Axon degeneration sculpts neuronal connectivity patterns during development and is an early hallmark of several adult-onset neurodegenerative disorders. Substantial progress has been made in identifying effector mechanisms driving axon fragmentation, but less is known about the upstream signaling pathways that initiate this process. Here, we investigate the behavior of the actin-spectrin-based Membrane-associated Periodic Skeleton (MPS), and effects of actin and spectrin manipulations in sensory axon degeneration. We show that trophic deprivation (TD) of mouse sensory neurons causes a rapid disassembly of the axonal MPS, which occurs prior to protein loss and independently of caspase activation. Actin destabilization initiates TD-related retrograde signaling needed for degeneration; actin stabilization prevents MPS disassembly and retrograde signaling during TD. Depletion of βII-spectrin, a key component of the MPS, suppresses retrograde signaling and protects axons against degeneration. These data demonstrate structural plasticity of the MPS and suggest its potential role in early steps of axon degeneration.
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Affiliation(s)
- Guiping Wang
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
| | - David J Simon
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
- Department of BiologyStanford UniversityStanfordUnited States
| | - Zhuhao Wu
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
| | - Deanna M Belsky
- Department of BiologyStanford UniversityStanfordUnited States
| | - Evan Heller
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
| | | | - Nicholas T Hertz
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
- Department of BiologyStanford UniversityStanfordUnited States
| | - Henrik Molina
- Proteomics Resource CenterThe Rockefeller UniversityNew YorkUnited States
| | - Guisheng Zhong
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
| | - Marc Tessier-Lavigne
- Laboratory of Brain Development and RepairThe Rockefeller UniversityNew YorkUnited States
- Department of BiologyStanford UniversityStanfordUnited States
| | - Xiaowei Zhuang
- Department of Chemistry and Chemical BiologyHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
- Department of PhysicsHoward Hughes Medical Institute, Harvard UniversityCambridgeUnited States
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28
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Sar Shalom H, Goldner R, Golan-Vaishenker Y, Yaron A. Balance between BDNF and Semaphorins gates the innervation of the mammary gland. eLife 2019; 8:41162. [PMID: 30628891 PMCID: PMC6328272 DOI: 10.7554/elife.41162] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 12/07/2018] [Indexed: 01/01/2023] Open
Abstract
The innervation of the mammary gland is controlled by brain-derived neurotrophic factor (BDNF), and sexually dimorphic sequestering of BDNF by the truncated form of TrkB (TrkB.T1) directs male-specific axonal pruning in mice. It is unknown whether other cues modulate these processes. We detected specific, non-dimorphic, expression of Semaphorin family members in the mouse mammary gland, which signal through PlexinA4. PlexinA4 deletion in both female and male embryos caused developmental hyperinnervation of the gland, which could be reduced by genetic co-reduction of BDNF. Moreover, in males, PlexinA4 ablation delayed axonal pruning, independently of the initial levels of innervation. In support of this, in vitro reduction of BDNF induced axonal hypersensitivity to PlexinA4 signaling. Overall, our study shows that precise sensory innervation of the mammary gland is regulated by the balance between trophic and repulsive signaling. Upon inhibition of trophic signaling, these repulsive factors may promote axonal pruning.
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Affiliation(s)
- Hadas Sar Shalom
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Ron Goldner
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Avraham Yaron
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovot, Israel
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29
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Quintá HR, Barrantes FJ. Damage and repair of the axolemmal membrane: From neural development to axonal trauma and restoration. CURRENT TOPICS IN MEMBRANES 2019; 84:169-185. [DOI: 10.1016/bs.ctm.2019.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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30
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IGARASHI M. Molecular basis of the functions of the mammalian neuronal growth cone revealed using new methods. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:358-377. [PMID: 31406059 PMCID: PMC6766448 DOI: 10.2183/pjab.95.026] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Accepted: 04/26/2019] [Indexed: 05/25/2023]
Abstract
The neuronal growth cone is a highly motile, specialized structure for extending neuronal processes. This structure is essential for nerve growth, axon pathfinding, and accurate synaptogenesis. Growth cones are important not only during development but also for plasticity-dependent synaptogenesis and neuronal circuit rearrangement following neural injury in the mature brain. However, the molecular details of mammalian growth cone function are poorly understood. This review examines molecular findings on the function of the growth cone as a result of the introduction of novel methods such superresolution microscopy and (phospho)proteomics. These results increase the scope of our understating of the molecular mechanisms of growth cone behavior in the mammalian brain.
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Affiliation(s)
- Michihiro IGARASHI
- Department of Neurochemistry and Molecular Cell Biology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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31
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Characterization of neurite dystrophy after trauma by high speed structured illumination microscopy and lattice light sheet microscopy. J Neurosci Methods 2018; 312:154-161. [PMID: 30529411 DOI: 10.1016/j.jneumeth.2018.12.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND Unbiased screening studies have repeatedly identified actin-related proteins as one of the families of proteins most influenced by neurotrauma. Nevertheless, the status quo model of cytoskeletal reorganization after neurotrauma excludes actin and incorporates only changes in microtubules and intermediate filaments. Actin is excluded in part because it is difficult to image with conventional techniques. However, recent innovations in fluorescent microscopy provide an opportunity to image the actin cytoskeleton at super-resolution resolution in living cells. This study applied these innovations to an in vitro model of neurotrauma. NEW METHOD New methods are introduced for traumatizing neurons before imaging them with high speed structured illumination microscopy or lattice light sheet microscopy. Also, methods for analyzing structured illumination microscopy images to quantify post-traumatic neurite dystrophy are presented. RESULTS Human induced pluripotent stem cell-derived neurons exhibited actin organization typical of immature neurons. Neurite dystrophy increased after trauma but was not influenced by jasplakinolide treatment. The F-actin content of dystrophies varied greatly from one dystrophy to another. COMPARISON WITH EXISTING METHODS In contrast to fixation dependent methods, these methods capture the evolution of the actin cytoskeleton over time in a living cell. In contrast to prior methods based on counting dystrophies, this quantification scheme parameterizes the severity of a given dystrophy as it evolves from a local swelling to an almost-perfect spheroid that threatens to transect the neurite. CONCLUSIONS These methods can be used to investigate genetic factors and therapeutic interventions that modulate the course of neurite dystrophy after trauma.
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32
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Hanson K, Tian N, Vickers JC, King AE. The HDAC6 Inhibitor Trichostatin A Acetylates Microtubules and Protects Axons From Excitotoxin-Induced Degeneration in a Compartmented Culture Model. Front Neurosci 2018; 12:872. [PMID: 30555293 PMCID: PMC6282003 DOI: 10.3389/fnins.2018.00872] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/08/2018] [Indexed: 12/15/2022] Open
Abstract
Axon degeneration has been implicated as a pathological process in several neurodegenerative diseases and acquired forms of neural injury. We have previously shown that stabilizing microtubules can protect axons against excitotoxin-induced fragmentation, however, the alterations of microtubules following excitotoxicity that results in axon degeneration are currently unknown. Hence, this study investigated whether excitotoxicity affects the post-translational modifications of microtubules and microtubule-associated proteins, and whether reversing these changes has the potential to rescue axons from degeneration. To investigate microtubule alterations, primary mouse cortical neurons at 10 days in vitro were treated with 10 or 25 μM kainic acid to induce excitotoxicity and axon degeneration. Post-translational modifications of microtubules and associated proteins were examined at 6 h following kainic acid exposure, relative to axon degeneration. While there were no changes to tyrosinated tubulin or MAP1B, acetylated tubulin was significantly (p < 0.05) decreased by 40% at 6 h post-treatment. To determine whether increasing microtubule acetylation prior to kainic acid exposure could prevent axon fragmentation, we investigated the effect of reducing microtubule deacetylation with the HDAC6 inhibitor, trichostatin A. We found that trichostatin A prevented kainic acid-induced microtubule deacetylation and significantly (p < 0.05) protected axons from fragmentation. These data suggest that microtubule acetylation is a potential target for axonal protection where excitotoxicity may play a role in neuronal degeneration.
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Affiliation(s)
- Kelsey Hanson
- Wicking Dementia Research and Education Centre, College of Health, University of Tasmania, Hobart, TAS, Australia
| | - Nan Tian
- Wicking Dementia Research and Education Centre, College of Health, University of Tasmania, Hobart, TAS, Australia
| | - James C Vickers
- Wicking Dementia Research and Education Centre, College of Health, University of Tasmania, Hobart, TAS, Australia
| | - Anna E King
- Wicking Dementia Research and Education Centre, College of Health, University of Tasmania, Hobart, TAS, Australia
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Mariano V, Domínguez-Iturza N, Neukomm LJ, Bagni C. Maintenance mechanisms of circuit-integrated axons. Curr Opin Neurobiol 2018; 53:162-173. [PMID: 30241058 DOI: 10.1016/j.conb.2018.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 08/14/2018] [Indexed: 12/21/2022]
Abstract
Adult, circuit-integrated neurons must be maintained and supported for the life span of their host. The attenuation of either maintenance or plasticity leads to impaired circuit function and ultimately to neurodegenerative disorders. Over the last few years, significant discoveries of molecular mechanisms were made that mediate the formation and maintenance of axons. Here, we highlight intrinsic and extrinsic mechanisms that ensure the health and survival of axons. We also briefly discuss examples of mutations associated with impaired axonal maintenance identified in specific neurological conditions. A better understanding of these mechanisms will therefore help to define targets for therapeutic interventions.
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Affiliation(s)
- Vittoria Mariano
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland; Department of Neurosciences KU Leuven, VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Nuria Domínguez-Iturza
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland; Department of Neurosciences KU Leuven, VIB Center for Brain and Disease Research, Leuven, Belgium
| | - Lukas J Neukomm
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland.
| | - Claudia Bagni
- Department of Fundamental Neurosciences, University of Lausanne, Switzerland; Department of Biomedicine and Prevention, University of Rome Tor Vergata, Italy.
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Morris CE. Cytotoxic Swelling of Sick Excitable Cells - Impaired Ion Homeostasis and Membrane Tension Homeostasis in Muscle and Neuron. CURRENT TOPICS IN MEMBRANES 2018; 81:457-496. [PMID: 30243439 DOI: 10.1016/bs.ctm.2018.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
When they become simultaneously leaky to both Na+ and Cl-, excitable cells are vulnerable to potentially lethal cytotoxic swelling. Swelling ensues in spite of an isosmotic milieu because the entering ions add osmolytes to the cytoplasm's high concentration of impermeant anionic osmolytes. An influx of osmotically-obliged water is unavoidable. A cell that cannot stanch at least one the leaks will succumb to death by Donnan effect. "Sick excitable cells" are those injured through ischemia, trauma, inflammation, hyperactivity, genetically-impaired membrane skeletons and other insults, all of which foster bleb-damage to regions of the plasma membrane. Nav channels resident in damaged membrane exhibit left-shifted kinetics; the corresponding Nav window conductance constitutes a Na+-leak. In cortical neurons, sustained depolarization to ∼-20mV elicits a sustained lethal gCl. Underlying Vrest in skeletal muscle is a constitutively active gCl; not surprisingly therefore, dystrophic muscle fibers, which are prone to bleb damage and which exhibit Nav-leak and Na+-overload, are prone to cytotoxic swelling. To restore viability in cytotoxically swelling neurons and muscle, the imperative of fully functional ion homeostasis is well-recognized. However, as emphasized here, in a healthy excitable cell, fully functional membrane tension homeostasis is also imperative. ATPase-pumps keep plasma membrane batteries charged, and ATPase-motor proteins maintain membrane tone. In sick excitable cells, neither condition prevails.
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Affiliation(s)
- Catherine E Morris
- Senior Scientist Emeritus, Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
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