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Yu CC(J, Barry NC, Wassie AT, Sinha A, Bhattacharya A, Asano S, Zhang C, Chen F, Hobert O, Goodman MB, Haspel G, Boyden ES. Expansion microscopy of C. elegans. eLife 2020; 9:e46249. [PMID: 32356725 PMCID: PMC7195193 DOI: 10.7554/elife.46249] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 03/30/2020] [Indexed: 12/20/2022] Open
Abstract
We recently developed expansion microscopy (ExM), which achieves nanoscale-precise imaging of specimens at ~70 nm resolution (with ~4.5x linear expansion) by isotropic swelling of chemically processed, hydrogel-embedded tissue. ExM of C. elegans is challenged by its cuticle, which is stiff and impermeable to antibodies. Here we present a strategy, expansion of C. elegans (ExCel), to expand fixed, intact C. elegans. ExCel enables simultaneous readout of fluorescent proteins, RNA, DNA location, and anatomical structures at resolutions of ~65-75 nm (3.3-3.8x linear expansion). We also developed epitope-preserving ExCel, which enables imaging of endogenous proteins stained by antibodies, and iterative ExCel, which enables imaging of fluorescent proteins after 20x linear expansion. We demonstrate the utility of the ExCel toolbox for mapping synaptic proteins, for identifying previously unreported proteins at cell junctions, and for gene expression analysis in multiple individual neurons of the same animal.
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Affiliation(s)
- Chih-Chieh (Jay) Yu
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Nicholas C Barry
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Asmamaw T Wassie
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Anubhav Sinha
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Division of Health Sciences and Technology, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Abhishek Bhattacharya
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Shoh Asano
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Chi Zhang
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
| | - Fei Chen
- Broad Institute of MIT and HarvardCambridgeUnited States
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia UniversityNew YorkUnited States
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford UniversityStanfordUnited States
| | - Gal Haspel
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University-NewarkNewarkUnited States
- The Brain Research Institute, New Jersey Institute of TechnologyNewarkUnited States
| | - Edward S Boyden
- Department of Biological Engineering, Massachusetts Institute of TechnologyCambridgeUnited States
- Media Lab, Massachusetts Institute of TechnologyCambridgeUnited States
- McGovern Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Koch Institute, Massachusetts Institute of TechnologyCambridgeUnited States
- Department of Brain and Cognitive Sciences, Massachusetts Institute of TechnologyCambridgeUnited States
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53
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Penke B, Szűcs M, Bogár F. Oligomerization and Conformational Change Turn Monomeric β-Amyloid and Tau Proteins Toxic: Their Role in Alzheimer's Pathogenesis. Molecules 2020; 25:molecules25071659. [PMID: 32260279 PMCID: PMC7180792 DOI: 10.3390/molecules25071659] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 03/29/2020] [Accepted: 03/31/2020] [Indexed: 12/13/2022] Open
Abstract
The structural polymorphism and the physiological and pathophysiological roles of two important proteins, β-amyloid (Aβ) and tau, that play a key role in Alzheimer's disease (AD) are reviewed. Recent results demonstrate that monomeric Aβ has important physiological functions. Toxic oligomeric Aβ assemblies (AβOs) may play a decisive role in AD pathogenesis. The polymorph fibrillar Aβ (fAβ) form has a very ordered cross-β structure and is assumed to be non-toxic. Tau monomers also have several important physiological actions; however, their oligomerization leads to toxic oligomers (TauOs). Further polymerization results in probably non-toxic fibrillar structures, among others neurofibrillary tangles (NFTs). Their structure was determined by cryo-electron microscopy at atomic level. Both AβOs and TauOs may initiate neurodegenerative processes, and their interactions and crosstalk determine the pathophysiological changes in AD. TauOs (perhaps also AβO) have prionoid character, and they may be responsible for cell-to-cell spreading of the disease. Both extra- and intracellular AβOs and TauOs (and not the previously hypothesized amyloid plaques and NFTs) may represent the novel targets of AD drug research.
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Affiliation(s)
- Botond Penke
- Department of Medical Chemistry, University of Szeged, H-6720 Szeged, Hungary; (M.S.); (F.B.)
- Correspondence:
| | - Mária Szűcs
- Department of Medical Chemistry, University of Szeged, H-6720 Szeged, Hungary; (M.S.); (F.B.)
| | - Ferenc Bogár
- Department of Medical Chemistry, University of Szeged, H-6720 Szeged, Hungary; (M.S.); (F.B.)
- MTA-SZTE Biomimetic Systems Research Group, University of Szeged, H-6720 Szeged, Hungary
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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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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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56
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Hauser M, Yan R, Li W, Repina NA, Schaffer DV, Xu K. The Spectrin-Actin-Based Periodic Cytoskeleton as a Conserved Nanoscale Scaffold and Ruler of the Neural Stem Cell Lineage. Cell Rep 2020; 24:1512-1522. [PMID: 30089262 PMCID: PMC6119594 DOI: 10.1016/j.celrep.2018.07.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 05/24/2018] [Accepted: 07/02/2018] [Indexed: 11/24/2022] Open
Abstract
Through three-dimensional STORM super-resolution microscopy, we resolve the spectrin-actin-based membrane cytoskeleton of neural stem cells (NSCs) and NSC-derived neurons, astrocytes, and oligodendrocytes. We show that undifferentiated NSCs are capable of forming patches of locally periodic, one-dimensional (1D) membrane cytoskeleton with ~180 nm periodicity. Such periodic structures become increasingly ordered and long-ranging as the NSCs mature into terminally differentiated neuronal and glial cell types, and, during this process, distinct 1D periodic ‘‘strips’’ dominate the flat 2D membranes. Moreover, we report remarkable alignment of the periodic cytoskeletons between abutting cells at axon-axon and axon-oligodendrocyte contacts and identify two adhesion molecules, neurofascin and L1CAM, as candidates to drive this nanoscale alignment. We thus show that a conserved 1D periodic membrane cytoskeletal motif serves as a nanoscale scaffold and ruler to mediate the physical interactions between cell types of the NSC lineage.
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Affiliation(s)
- Meghan Hauser
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Rui Yan
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Wan Li
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Nicole A Repina
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David V Schaffer
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Ke Xu
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Division of Molecular Biophysics and Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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57
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Coakley S, Ritchie FK, Galbraith KM, Hilliard MA. Epidermal control of axonal attachment via β-spectrin and the GTPase-activating protein TBC-10 prevents axonal degeneration. Nat Commun 2020; 11:133. [PMID: 31919407 PMCID: PMC6952388 DOI: 10.1038/s41467-019-13795-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 11/28/2019] [Indexed: 12/28/2022] Open
Abstract
Neurons are subjected to strain due to body movement and their location within organs and tissues. However, how they withstand these forces over the lifetime of an organism is still poorly understood. Here, focusing on touch receptor neuron-epidermis interactions using Caenorhabditis elegans as a model system, we show that UNC-70/β-spectrin and TBC-10, a conserved GTPase-activating protein, function non-cell-autonomously within the epidermis to dynamically maintain attachment of the axon. We reveal that, in response to strain, UNC-70/β-spectrin and TBC-10 stabilize trans-epidermal hemidesmosome attachment structures which otherwise become lost, causing axonal breakage and degeneration. Furthermore, we show that TBC-10 regulates axonal attachment and maintenance by inactivating RAB-35, and reveal functional conservation of these molecules with their vertebrate orthologs. Finally, we demonstrate that β-spectrin functions in this context non-cell-autonomously. We propose a model in which mechanically resistant epidermal attachment structures are maintained by UNC-70/β-spectrin and TBC-10 during movement, preventing axonal detachment and degeneration.
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Affiliation(s)
- Sean Coakley
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Fiona K Ritchie
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Kate M Galbraith
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia
| | - Massimo A Hilliard
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, 4072, Australia.
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58
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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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59
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Of Molecules and Mechanisms. J Neurosci 2019; 40:81-88. [PMID: 31630114 DOI: 10.1523/jneurosci.0743-19.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 08/25/2019] [Accepted: 08/31/2019] [Indexed: 11/21/2022] Open
Abstract
Without question, molecular biology drives modern neuroscience. The past 50 years has been nothing short of revolutionary as key findings have moved the field from correlation toward causation. Most obvious are the discoveries and strategies that have been used to build tools for visualizing circuits, measuring activity, and regulating behavior. Less flashy, but arguably as important are the myriad investigations uncovering the actions of single molecules, macromolecular structures, and integrated machines that serve as the basis for constructing cellular and signaling pathways identified in wide-scale gene or RNA studies and for feeding data into informational networks used in systems biology. This review follows the pathways that were opened in neuroscience by major discoveries and set the stage for the next 50 years.
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60
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de Wit G, Albrecht D, Ewers H, Kukura P. Revealing Compartmentalized Diffusion in Living Cells with Interferometric Scattering Microscopy. Biophys J 2019; 114:2945-2950. [PMID: 29925030 DOI: 10.1016/j.bpj.2018.05.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/08/2018] [Accepted: 05/02/2018] [Indexed: 12/19/2022] Open
Abstract
The spatiotemporal organization and dynamics of the plasma membrane and its constituents are central to cellular function. Fluorescence-based single-particle tracking has emerged as a powerful approach for studying the single molecule behavior of plasma-membrane-associated events because of its excellent background suppression, at the expense of imaging speed and observation time. Here, we show that interferometric scattering microscopy combined with 40 nm gold nanoparticle labeling can be used to follow the motion of membrane proteins in the plasma membrane of live cultured mammalian cell lines and hippocampal neurons with up to 3 nm precision and 25 μs temporal resolution. The achievable spatiotemporal precision enabled us to reveal signatures of compartmentalization in neurons likely caused by the actin cytoskeleton.
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Affiliation(s)
- Gabrielle de Wit
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom
| | - David Albrecht
- MRC Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Helge Ewers
- Department of Biochemistry, Freie Universität Berlin, Berlin, Germany
| | - Philipp Kukura
- Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, Oxford, United Kingdom.
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61
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Zhou R, Han B, Xia C, Zhuang X. Membrane-associated periodic skeleton is a signaling platform for RTK transactivation in neurons. Science 2019; 365:929-934. [PMID: 31467223 PMCID: PMC7063502 DOI: 10.1126/science.aaw5937] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/02/2019] [Indexed: 01/23/2023]
Abstract
Actin, spectrin, and related molecules form a membrane-associated periodic skeleton (MPS) in neurons. The function of the MPS, however, remains poorly understood. Using super-resolution imaging, we observed that G protein-coupled receptors (GPCRs), cell adhesion molecules (CAMs), receptor tyrosine kinases (RTKs), and related signaling molecules were recruited to the MPS in response to extracellular stimuli, resulting in colocalization of these molecules and RTK transactivation by GPCRs and CAMs, giving rise to extracellular signal-regulated kinase (ERK) signaling. Disruption of the MPS prevented such molecular colocalizations and downstream ERK signaling. ERK signaling in turn caused calpain-dependent MPS degradation, providing a negative feedback that modulates signaling strength. These results reveal an important functional role of the MPS and establish it as a dynamically regulated platform for GPCR- and CAM-mediated RTK signaling.
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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
| | - 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
| | - 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
| | - 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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Reshetniak S, Rizzoli SO. Interrogating Synaptic Architecture: Approaches for Labeling Organelles and Cytoskeleton Components. Front Synaptic Neurosci 2019; 11:23. [PMID: 31507402 PMCID: PMC6716447 DOI: 10.3389/fnsyn.2019.00023] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Accepted: 08/02/2019] [Indexed: 01/06/2023] Open
Abstract
Synaptic transmission has been studied for decades, as a fundamental step in brain function. The structure of the synapse, and its changes during activity, turned out to be key aspects not only in the transfer of information between neurons, but also in cognitive processes such as learning and memory. The overall synaptic morphology has traditionally been studied by electron microscopy, which enables the visualization of synaptic structure in great detail. The changes in the organization of easily identified structures, such as the presynaptic active zone, or the postsynaptic density, are optimally studied via electron microscopy. However, few reliable methods are available for labeling individual organelles or protein complexes in electron microscopy. For such targets one typically relies either on combination of electron and fluorescence microscopy, or on super-resolution fluorescence microscopy. This review focuses on approaches and techniques used to specifically reveal synaptic organelles and protein complexes, such as cytoskeletal assemblies. We place the strongest emphasis on methods detecting the targets of interest by affinity binding, and we discuss the advantages and limitations of each method.
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Affiliation(s)
- Sofiia Reshetniak
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration (BIN), University Medical Center Göttingen, Göttingen, Germany
- International Max Planck Research School for Molecular Biology, Göttingen, Germany
| | - Silvio O. Rizzoli
- Institute for Neuro- and Sensory Physiology, Center for Biostructural Imaging of Neurodegeneration (BIN), University Medical Center Göttingen, Göttingen, Germany
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64
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Jia R, Li D, Li M, Chai Y, Liu Y, Xie Z, Shao W, Xie C, Li L, Huang X, Chen L, Li W, Ou G. Spectrin-based membrane skeleton supports ciliogenesis. PLoS Biol 2019; 17:e3000369. [PMID: 31299042 PMCID: PMC6655744 DOI: 10.1371/journal.pbio.3000369] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 07/24/2019] [Accepted: 06/25/2019] [Indexed: 12/14/2022] Open
Abstract
Cilia are remarkable cellular devices that power cell motility and transduce extracellular signals. To assemble a cilium, a cylindrical array of 9 doublet microtubules push out an extension of the plasma membrane. Membrane tension regulates cilium formation; however, molecular pathways that link mechanical stimuli to ciliogenesis are unclear. Using genome editing, we introduced hereditary elliptocytosis (HE)- and spinocerebellar ataxia (SCA)-associated mutations into the Caenorhabditis elegans membrane skeletal protein spectrin. We show that these mutations impair mechanical support for the plasma membrane and change cell shape. RNA sequencing (RNA-seq) analyses of spectrin-mutant animals uncovered a global down-regulation of ciliary gene expression, prompting us to investigate whether spectrin participates in ciliogenesis. Spectrin mutations affect intraflagellar transport (IFT), disrupt axonemal microtubules, and inhibit cilium formation, and the endogenous spectrin periodically distributes along cilia. Mammalian spectrin also localizes in cilia and regulates ciliogenesis. These results define a previously unrecognized yet conserved role of spectrin-based mechanical support for cilium biogenesis.
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Affiliation(s)
- Ru Jia
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Dongdong Li
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Ming Li
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Yongping Chai
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Yufan Liu
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Zhongyun Xie
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Wenxin Shao
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Chao Xie
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
| | - Liuju Li
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Xiaoshuai Huang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Liangyi Chen
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Wei Li
- School of Medicine, Tsinghua University, Beijing, China
| | - Guangshuo Ou
- Tsinghua-Peking Center for Life Sciences, Beijing Frontier Research Center for Biological Structure, School of Life Sciences and MOE Key Laboratory for Protein Science, Tsinghua University, Beijing, China
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65
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Mishin AS, Lukyanov KA. Live-Cell Super-resolution Fluorescence Microscopy. BIOCHEMISTRY (MOSCOW) 2019; 84:S19-S31. [PMID: 31213193 DOI: 10.1134/s0006297919140025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Super-resolution fluorescence microscopy (nanoscopy) enables imaging with a spatial resolution much higher than the diffraction limit of optical microscopy. However, the methods of fluorescence nanoscopy are still poorly suitable for studying living cells. In this review, we describe some of methods for nanoscopy and specific fluorescent labeling aimed to decrease the damaging effects of light illumination on live samples.
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Affiliation(s)
- A S Mishin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
| | - K A Lukyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
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66
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van Bommel B, Konietzny A, Kobler O, Bär J, Mikhaylova M. F-actin patches associated with glutamatergic synapses control positioning of dendritic lysosomes. EMBO J 2019; 38:e101183. [PMID: 31267565 PMCID: PMC6669925 DOI: 10.15252/embj.2018101183] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 05/27/2019] [Accepted: 05/29/2019] [Indexed: 12/31/2022] Open
Abstract
Organelle positioning within neurites is required for proper neuronal function. In dendrites, with their complex cytoskeletal organization, transport of organelles is guided by local specializations of the microtubule and actin cytoskeleton, and by coordinated activity of different motor proteins. Here, we focus on the actin cytoskeleton in the dendritic shaft and describe dense structures consisting of longitudinal and branched actin filaments. These actin patches are devoid of microtubules and are frequently located at the base of spines, or form an actin mesh around excitatory shaft synapses. Using lysosomes as an example, we demonstrate that the presence of actin patches has a strong impact on dendritic organelle transport, as lysosomes frequently stall at these locations. We provide mechanistic insights on this pausing behavior, demonstrating that actin patches form a physical barrier for kinesin-driven cargo. In addition, we identify myosin Va as an active tether which mediates long-term stalling. This correlation between the presence of actin meshes and halting of organelles could be a generalized principle by which synapses control organelle trafficking.
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Affiliation(s)
- Bas van Bommel
- DFG Emmy Noether Group "Neuronal Protein Transport", Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anja Konietzny
- DFG Emmy Noether Group "Neuronal Protein Transport", Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Oliver Kobler
- Combinatorial Neuroimaging Core Facility (CNI), Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - Julia Bär
- DFG Emmy Noether Group "Neuronal Protein Transport", Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marina Mikhaylova
- DFG Emmy Noether Group "Neuronal Protein Transport", Center for Molecular Neurobiology, ZMNH, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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67
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Machnicka B, Grochowalska R, Bogusławska DM, Sikorski AF. The role of spectrin in cell adhesion and cell-cell contact. Exp Biol Med (Maywood) 2019; 244:1303-1312. [PMID: 31226892 DOI: 10.1177/1535370219859003] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Spectrins are proteins that are responsible for many aspects of cell function and adaptation to changing environments. Primarily the spectrin-based membrane skeleton maintains cell membrane integrity and its mechanical properties, together with the cytoskeletal network a support cell shape. The occurrence of a variety of spectrin isoforms in diverse cellular environments indicates that it is a multifunctional protein involved in numerous physiological pathways. Participation of spectrin in cell–cell and cell–extracellular matrix adhesion and formation of dynamic plasma membrane protrusions and associated signaling events is a subject of interest for researchers in the fields of cell biology and molecular medicine. In this mini-review, we focus on data concerning the role of spectrins in cell surface activities such as adhesion, cell–cell contact, and invadosome formation. We discuss data on different adhesion proteins that directly or indirectly interact with spectrin repeats. New findings support the involvement of spectrin in cell adhesion and spreading, formation of lamellipodia, and also the participation in morphogenetic processes, such as eye development, oogenesis, and angiogenesis. Here, we review the role of spectrin in cell adhesion and cell–cell contact.Impact statementThis article reviews properties of spectrins as a group of proteins involved in cell surface activities such as, adhesion and cell–cell contact, and their contribution to morphogenesis. We show a new area of research and discuss the involvement of spectrin in regulation of cell–cell contact leading to immunological synapse formation and in shaping synapse architecture during myoblast fusion. Data indicate involvement of spectrins in adhesion and cell–cell or cell–extracellular matrix interactions and therefore in signaling pathways. There is evidence of spectrin’s contribution to the processes of morphogenesis which are connected to its interactions with adhesion molecules, membrane proteins (and perhaps lipids), and actin. Our aim was to highlight the essential role of spectrin in cell–cell contact and cell adhesion.
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Affiliation(s)
- Beata Machnicka
- Department of Biochemistry and Bioinformatics, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra 65-516, Poland
| | - Renata Grochowalska
- Department of Biochemistry and Bioinformatics, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra 65-516, Poland
| | - Dżamila M Bogusławska
- Department of Biochemistry and Bioinformatics, Faculty of Biological Sciences, University of Zielona Góra, Zielona Góra 65-516, Poland
| | - Aleksander F Sikorski
- Department of Cytobiochemistry, Faculty of Biotechnology, University of Wrocław, Wrocław 50-383, Poland
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68
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Liu CH, Rasband MN. Axonal Spectrins: Nanoscale Organization, Functional Domains and Spectrinopathies. Front Cell Neurosci 2019; 13:234. [PMID: 31191255 PMCID: PMC6546920 DOI: 10.3389/fncel.2019.00234] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 05/09/2019] [Indexed: 11/13/2022] Open
Abstract
Spectrin cytoskeletons are found in all metazoan cells, and their physical interactions between actin and ankyrins establish a meshwork that provides cellular structural integrity. With advanced super-resolution microscopy, the intricate spatial organization and associated functional properties of these cytoskeletons can now be analyzed with unprecedented clarity. Long neuronal processes like peripheral sensory and motor axons may be subject to intense mechanical forces including bending, stretching, and torsion. The spectrin-based cytoskeleton is essential to protect axons against these mechanical stresses. Additionally, spectrins are critical for the assembly and maintenance of axonal excitable domains including the axon initial segment and the nodes of Ranvier (NoR). These sites facilitate rapid and efficient action potential initiation and propagation in the nervous system. Recent studies revealed that pathogenic spectrin variants and diseases that protealyze and breakdown spectrins are associated with congenital neurological disorders and nervous system injury. Here, we review recent studies of spectrins in the nervous system and focus on their functions in axonal health and disease.
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Affiliation(s)
- Cheng-Hsin Liu
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States
| | - Matthew Neil Rasband
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, TX, United States
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69
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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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70
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Liu Y, Qi J, Chen X, Tang M, Chu C, Zhu W, Li H, Tian C, Yang G, Zhong C, Zhang Y, Ni G, He S, Chai R, Zhong G. Critical role of spectrin in hearing development and deafness. SCIENCE ADVANCES 2019; 5:eaav7803. [PMID: 31001589 PMCID: PMC6469942 DOI: 10.1126/sciadv.aav7803] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 03/01/2019] [Indexed: 06/09/2023]
Abstract
Inner ear hair cells (HCs) detect sound through the deflection of mechanosensory stereocilia. Stereocilia are inserted into the cuticular plate of HCs by parallel actin rootlets, where they convert sound-induced mechanical vibrations into electrical signals. The molecules that support these rootlets and enable them to withstand constant mechanical stresses underpin our ability to hear. However, the structures of these molecules have remained unknown. We hypothesized that αII- and βII-spectrin subunits fulfill this role, and investigated their structural organization in rodent HCs. Using super-resolution fluorescence imaging, we found that spectrin formed ring-like structures around the base of stereocilia rootlets. These spectrin rings were associated with the hearing ability of mice. Further, HC-specific, βII-spectrin knockout mice displayed profound deafness. Overall, our work has identified and characterized structures of spectrin that play a crucial role in mammalian hearing development.
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Affiliation(s)
- Yan Liu
- iHuman Institute, ShanghaiTech University, Shanghai, China
| | - Jieyu Qi
- iHuman Institute, ShanghaiTech University, Shanghai, China
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, China
| | - Xin Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Mingliang Tang
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, China
| | - Cenfeng Chu
- iHuman Institute, ShanghaiTech University, Shanghai, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Weijie Zhu
- iHuman Institute, ShanghaiTech University, Shanghai, China
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, China
| | - Hui Li
- iHuman Institute, ShanghaiTech University, Shanghai, China
| | - Cuiping Tian
- iHuman Institute, ShanghaiTech University, Shanghai, China
| | - Guang Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai, China
| | - Chao Zhong
- School of Physical Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ying Zhang
- Department of Medical Neuroscience, Faculty of Medicine, Dalhousie University, 5850 College Street, Halifax, Canada
| | - Guangjian Ni
- Academy of Medical Engineering and Translational Medicine, Tianjin University, Tianjin, China
- Laboratory of Neural Engineering and Rehabilitation, Department of Biomedical Engineering, College of Precision Instruments and Optoelectronics Engineering, Tianjin University, Tianjin, China
| | - Shuijin He
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Renjie Chai
- Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
- Research Institute of Otolaryngology, No.321 Zhongshan Road, Nanjing, China
- Beijing Key Laboratory of Neural Regeneration and Repair, Capital Medical University, Beijing, 100069, China
| | - Guisheng Zhong
- iHuman Institute, ShanghaiTech University, Shanghai, China
- Co-innovation Center of Neuroregeneration, Jiangsu Key Laboratory of Neuroregeneration, Nantong University, Nantong, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Guangzhou Institute of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China
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71
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Campbell CL, Saavedra-Rodriguez K, Kubik TD, Lenhart A, Lozano-Fuentes S, Black WC. Vgsc-interacting proteins are genetically associated with pyrethroid resistance in Aedes aegypti. PLoS One 2019; 14:e0211497. [PMID: 30695054 PMCID: PMC6350986 DOI: 10.1371/journal.pone.0211497] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 01/15/2019] [Indexed: 11/18/2022] Open
Abstract
Association mapping of factors that condition pyrethroid resistance in Aedes aegypti has consistently identified genes in multiple functional groups. Toward better understanding of the mechanisms involved, we examined high throughput sequencing data (HTS) from two Aedes aegypti aegypti collections from Merida, Yucatan, Mexico treated with either permethrin or deltamethrin. Exome capture enrichment for coding regions and the AaegL5 annotation were used to identify genes statistically associated with resistance. The frequencies of single nucleotide polymorphisms (SNPs) were compared between resistant and susceptible mosquito pools using a contingency χ2 analysis. The -log10(χ2p value) was calculated at each SNP site, with a weighted average determined from all sites in each gene. Genes with -log10(χ2p value) ≥ 4.0 and present among all 3 treatment groups were subjected to gene set enrichment analysis (GSEA). We found that several functional groups were enriched compared to all coding genes. These categories were transport, signal transduction and metabolism, in order from highest to lowest statistical significance. Strikingly, 21 genes with demonstrated association to synaptic function were identified. In the high association group (n = 1,053 genes), several genes were identified that also genetically or physically interact with the voltage-gated sodium channel (VGSC). These genes were eg., CHARLATAN (CHL), a transcriptional regulator, several ankyrin-domain proteins, PUMILIO (PUM), a translational repressor, and NEDD4 (E3 ubiquitin-protein ligase). There were 13 genes that ranked among the top 10%: these included VGSC; CINGULIN, a predicted neuronal gap junction protein, and the aedine ortholog of NERVY (NVY), a transcriptional regulator. Silencing of CHL and NVY followed by standard permethrin bottle bioassays validated their association with permethrin resistance. Importantly, VGSC levels were also reduced about 50% in chl- or nvy-dsRNA treated mosquitoes. These results are consistent with the contribution of a variety of neuronal pathways to pyrethroid resistance in Ae. aegypti.
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Affiliation(s)
- Corey L Campbell
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Karla Saavedra-Rodriguez
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Tristan D Kubik
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Audrey Lenhart
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Saul Lozano-Fuentes
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - William C Black
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
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72
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Chakrabarty N, Dubey P, Tang Y, Ganguly A, Ladt K, Leterrier C, Jung P, Roy S. Processive flow by biased polymerization mediates the slow axonal transport of actin. J Cell Biol 2019; 218:112-124. [PMID: 30401699 PMCID: PMC6314539 DOI: 10.1083/jcb.201711022] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 09/02/2018] [Accepted: 10/25/2018] [Indexed: 12/15/2022] Open
Abstract
Classic pulse-chase studies have shown that actin is conveyed in slow axonal transport, but the mechanistic basis for this movement is unknown. Recently, we reported that axonal actin was surprisingly dynamic, with focal assembly/disassembly events ("actin hotspots") and elongating polymers along the axon shaft ("actin trails"). Using a combination of live imaging, superresolution microscopy, and modeling, in this study, we explore how these dynamic structures can lead to processive transport of actin. We found relatively more actin trails elongated anterogradely as well as an overall slow, anterogradely biased flow of actin in axon shafts. Starting with first principles of monomer/filament assembly and incorporating imaging data, we generated a quantitative model simulating axonal hotspots and trails. Our simulations predict that the axonal actin dynamics indeed lead to a slow anterogradely biased flow of the population. Collectively, the data point to a surprising scenario where local assembly and biased polymerization generate the slow axonal transport of actin without involvement of microtubules (MTs) or MT-based motors. Mechanistically distinct from polymer sliding, this might be a general strategy to convey highly dynamic cytoskeletal cargoes.
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Affiliation(s)
- Nilaj Chakrabarty
- Department of Physics and Astronomy, Neuroscience Program and Quantitative Biology Institute, Ohio University, Athens, OH
| | - Pankaj Dubey
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI
| | - Yong Tang
- Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA
| | - Archan Ganguly
- Department of Neurosciences, University of California, San Diego, La Jolla, CA
| | - Kelsey Ladt
- Department of Neurosciences, University of California, San Diego, La Jolla, CA
| | - Christophe Leterrier
- Aix-Marseille Université, Centre National de la Recherche Scientifique, Institut Neurophysiopathol, NeuroCyto, Marseille, France
| | - Peter Jung
- Department of Physics and Astronomy, Neuroscience Program and Quantitative Biology Institute, Ohio University, Athens, OH
| | - Subhojit Roy
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI
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73
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Sahl SJ, Schönle A, Hell SW. Fluorescence Microscopy with Nanometer Resolution. SPRINGER HANDBOOK OF MICROSCOPY 2019. [DOI: 10.1007/978-3-030-00069-1_22] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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74
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Branching mechanisms shaping dendrite architecture. Dev Biol 2018; 451:16-24. [PMID: 30550882 DOI: 10.1016/j.ydbio.2018.12.005] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 11/19/2018] [Accepted: 12/05/2018] [Indexed: 12/11/2022]
Abstract
A neuron's contribution to the information flow within a neural circuit is governed by the structure of its dendritic arbor. The geometry of the dendritic arbor directly determines synaptic density and the size of the receptive field, both of which influence the firing pattern of the neuron. Importantly, the position of individual dendritic branches determines the identity of the neuron's presynaptic partner and thus the nature of the incoming sensory information. To generate the unique stereotypic architecture of a given neuronal subtype, nascent branches must emerge from the dendritic shaft at preprogramed branch points. Subsequently, a complex array of extrinsic factors regulates the degree and orientation of branch expansion to ensure maximum coverage of the receptive field whilst constraining growth within predetermined territories. In this review we focus on studies that best illustrate how environmental cues such as the Wnts and Netrins and their receptors sculpt the dendritic arbor. We emphasize the pivotal role played by the actin cytoskeleton and its upstream regulators in branch initiation, outgrowth and navigation. Finally, we discuss how protocadherin and DSCAM contact-mediated repulsion prevents inappropriate synapse formation between sister dendrites or dendrites and the axon from the same neuron. Together these studies highlight the clever ways evolution has solved the problem of constructing complex branch geometries.
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75
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Gartner V, Markello TC, Macnamara E, De Biase A, Thurm A, Joseph L, Beggs A, Schmahmann JD, Berry GT, Anselm I, Boslet E, Tifft CJ, Gahl WA, Lee PR. Novel variants in SPTAN1 without epilepsy: An expansion of the phenotype. Am J Med Genet A 2018; 176:2768-2776. [PMID: 30548380 PMCID: PMC11157598 DOI: 10.1002/ajmg.a.40628] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 07/19/2018] [Accepted: 08/13/2018] [Indexed: 11/11/2022]
Abstract
We describe two unrelated children with de novo variants in the non-erythrocytic alpha-II-spectrin (SPTAN1) gene who have hypoplastic brain structures, intellectual disability, and both fine and gross motor impairments. Using agnostic exome sequencing, we identified a nonsense variant creating a premature stop codon in exon 21 of SPTAN1, and in a second patient we identified an intronic substitution in SPTAN1 prior to exon 50 creating a new donor acceptor site. Neither of these variants has been described previously. Although some of these patients' features are consistent with the known SPTAN1 encephalopathy phenotype, these two children do not have epilepsy, in contrast to reports about nearly every other patient with heterozygous SPTAN1 variants and in all patients with a variant near the C-terminal coding region. Moreover, both children have abnormal thyroid function, which has not been previously reported in association with SPTAN1 variant. We present a detailed discussion of the clinical manifestations of these two unique SPTAN1 variants and provide evidence that both variants result in reduced mRNA expression despite different locations within the gene and clinical phenotypes. These findings expand the motor, cognitive, and behavioral spectrum of the SPTAN1-associated phenotype and invite speculation about underlying pathophysiologies.
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Affiliation(s)
- Valerie Gartner
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
| | - Thomas C. Markello
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
| | - Ellen Macnamara
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
| | | | - Audrey Thurm
- Neurodevelopmental and Behavioral Phenotyping Service, Office of the Clinical Director, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Lisa Joseph
- Neurodevelopmental and Behavioral Phenotyping Service, Office of the Clinical Director, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland
| | - Alan Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jeremy D. Schmahmann
- Ataxia Unit, Cognitive Behavioral Neurology Unit, Laboratory for Neuroanatomy and Cerebellar Neurobiology, Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts
| | - Gerard T. Berry
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts
| | - Irina Anselm
- Department of Neurology, Boston Children’s Hospital and Harvard Medical School, Boston, Massachusetts
| | - Emma Boslet
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
| | - Cynthia J. Tifft
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
| | - William A. Gahl
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
| | - Paul R. Lee
- Office of the Clinical Director, NHGRI, and NIH Undiagnosed Diseases Program, Office of the Director, National Institutes of Health, Bethesda, Maryland
- Division of Neurology Products, Center for Drug Evaluation and Research, Food and Drug Administration, Silver Spring, Maryland
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76
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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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77
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Costa AR, Pinto-Costa R, Sousa SC, Sousa MM. The Regulation of Axon Diameter: From Axonal Circumferential Contractility to Activity-Dependent Axon Swelling. Front Mol Neurosci 2018; 11:319. [PMID: 30233318 PMCID: PMC6131297 DOI: 10.3389/fnmol.2018.00319] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 08/17/2018] [Indexed: 01/08/2023] Open
Abstract
In the adult nervous system axon caliber varies widely amongst different tracts. When considering a given axon, its diameter can further fluctuate in space and time, according to processes including the distribution of organelles and activity-dependent mechanisms. In addition, evidence is emerging supporting that in axons circumferential tension/contractility is present. Axonal diameter is generically regarded as being regulated by neurofilaments. When neurofilaments are absent or low, microtubule-dependent mechanisms can also contribute to the regulation of axon caliber. Despite this knowledge, the fine-tune mechanisms controlling diameter and circumferential tension throughout the lifetime of an axon, remain largely elusive. Recent data supports the role of the actin-spectrin-based membrane periodic skeleton and of non-muscle myosin II in the control of axon diameter. However, the cytoskeletal arrangement that underlies circumferential axonal contraction and expansion is still to be discovered. Here, we discuss in a critical viewpoint the existing knowledge on the regulation of axon diameter, with a specific focus on the possible role played by the axonal actin cytoskeleton.
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Affiliation(s)
- Ana Rita Costa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC) and Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal
| | - Rita Pinto-Costa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC) and Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Porto, Portugal
| | - Sara Castro Sousa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC) and Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal
| | - Mónica Mendes Sousa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC) and Instituto de Inovação e Investigação em Saúde, University of Porto, Porto, Portugal
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78
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Sigal YM, Zhou R, Zhuang X. Visualizing and discovering cellular structures with super-resolution microscopy. Science 2018; 361:880-887. [PMID: 30166485 DOI: 10.1126/science.aau1044] [Citation(s) in RCA: 359] [Impact Index Per Article: 59.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Super-resolution microscopy has overcome a long-held resolution barrier-the diffraction limit-in light microscopy and enabled visualization of previously invisible molecular details in biological systems. Since their conception, super-resolution imaging methods have continually evolved and can now be used to image cellular structures in three dimensions, multiple colors, and living systems with nanometer-scale resolution. These methods have been applied to answer questions involving the organization, interaction, stoichiometry, and dynamics of individual molecular building blocks and their integration into functional machineries in cells and tissues. In this Review, we provide an overview of super-resolution methods, their state-of-the-art capabilities, and their constantly expanding applications to biology, with a focus on the latter. We will also describe the current technical challenges and future advances anticipated in super-resolution imaging.
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Affiliation(s)
- Yaron M Sigal
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Ruobo Zhou
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Xiaowei Zhuang
- Howard Hughes Medical Institute, Department of Chemistry and Chemical Biology, Department of Physics, Harvard University, Cambridge, MA 02138, USA.
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79
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Mutalik SP, Joseph J, Pullarkat PA, Ghose A. Cytoskeletal Mechanisms of Axonal Contractility. Biophys J 2018; 115:713-724. [PMID: 30054033 DOI: 10.1016/j.bpj.2018.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Revised: 04/13/2018] [Accepted: 07/06/2018] [Indexed: 11/18/2022] Open
Abstract
Mechanotransduction is likely to be an important mechanism of signaling in thin, elongated cells such as neurons. Maintenance of prestress or rest tension may facilitate mechanotransduction in these cells. In recent years, functional roles for mechanical tension in neuronal development and physiology are beginning to emerge, but the cellular mechanisms regulating neurite tension remain poorly understood. Active contraction of neurites is a potential mechanism of tension regulation. In this study, we have explored cytoskeletal mechanisms mediating active contractility of neuronal axons. We have developed a simple assay in which we evaluate contraction of curved axons upon trypsin-mediated detachment. We show that curved axons undergo contraction and straighten upon deadhesion. Axonal straightening was found to be actively driven by actomyosin contractility, whereas microtubules may subserve a secondary role. We find that although axons show a monotonous decrease in length upon contraction, subcellularly, the cytoskeleton shows a heterogeneous contractile response. Further, using an assay for spontaneous development of tension without trypsin-induced deadhesion, we show that axons are intrinsically contractile. These experiments, using novel experimental approaches, implicate the axonal cytoskeleton in tension homeostasis. Our data suggest that although globally, the axon behaves as a mechanical continuum, locally, the cytoskeleton is remodeled heterogeneously.
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Affiliation(s)
- Sampada P Mutalik
- Indian Institute of Science Education and Research Pune, Pune, Maharashtra, India
| | - Joby Joseph
- Center for Neural and Cognitive Sciences, University of Hyderabad, Hyderabad, Telangana, India
| | | | - Aurnab Ghose
- Indian Institute of Science Education and Research Pune, Pune, Maharashtra, India.
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80
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Karagiannis ED, Boyden ES. Expansion microscopy: development and neuroscience applications. Curr Opin Neurobiol 2018; 50:56-63. [PMID: 29316506 PMCID: PMC5984670 DOI: 10.1016/j.conb.2017.12.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Revised: 11/30/2017] [Accepted: 12/16/2017] [Indexed: 01/01/2023]
Abstract
Many neuroscience questions center around understanding how the molecules and wiring in neural circuits mechanistically yield behavioral functions, or go awry in disease states. However, mapping the molecules and wiring of neurons across the large scales of neural circuits has posed a great challenge. We recently developed expansion microscopy (ExM), a process in which we physically magnify biological specimens such as brain circuits. We synthesize throughout preserved brain specimens a dense, even mesh of a swellable polymer such as sodium polyacrylate, anchoring key biomolecules such as proteins and nucleic acids to the polymer. After mechanical homogenization of the specimen-polymer composite, we add water, and the polymer swells, pulling biomolecules apart. Due to the larger separation between molecules, ordinary microscopes can then perform nanoscale resolution imaging. We here review the ExM technology as well as applications to the mapping of synapses, cells, and circuits, including deployment in species such as Drosophila, mouse, non-human primate, and human.
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Affiliation(s)
| | - Edward S Boyden
- MIT Media Lab, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA; McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA; Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.
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81
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Unsain N, Stefani FD, Cáceres A. The Actin/Spectrin Membrane-Associated Periodic Skeleton in Neurons. Front Synaptic Neurosci 2018; 10:10. [PMID: 29875650 PMCID: PMC5974029 DOI: 10.3389/fnsyn.2018.00010] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 05/04/2018] [Indexed: 11/28/2022] Open
Abstract
Neurons are the most asymmetric cell types, with their axons commonly extending over lengths that are thousand times longer than the diameter of the cell soma. Fluorescence nanoscopy has recently unveiled that actin, spectrin and accompanying proteins form a membrane-associated periodic skeleton (MPS) that is ubiquitously present in mature axons from all neuronal types evaluated so far. The MPS is a regular supramolecular protein structure consisting of actin “rings” separated by spectrin tetramer “spacers”. Although the MPS is best organized in axons, it is also present in dendrites, dendritic spine necks and thin cellular extensions of non-neuronal cells such as oligodendrocytes and microglia. The unique organization of the actin/spectrin skeleton has raised the hypothesis that it might serve to support the extreme physical and structural conditions that axons must resist during the lifespan of an organism. Another plausible function of the MPS consists of membrane compartmentalization and subsequent organization of protein domains. This review focuses on what we know so far about the structure of the MPS in different neuronal subdomains, its dynamics and the emerging evidence of its impact in axonal biology.
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Affiliation(s)
- Nicolas Unsain
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina.,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
| | - Alfredo Cáceres
- Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Córdoba, Argentina.,Universidad Nacional de Córdoba, Córdoba, Argentina.,Instituto Universitario Ciencias Biomédicas de Córdoba (IUCBC), Córdoba, Argentina
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82
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Gangatharan G, Schneider-Maunoury S, Breau MA. Role of mechanical cues in shaping neuronal morphology and connectivity. Biol Cell 2018; 110:125-136. [PMID: 29698566 DOI: 10.1111/boc.201800003] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2018] [Accepted: 04/09/2018] [Indexed: 02/06/2023]
Abstract
Neuronal circuits, the functional building blocks of the nervous system, assemble during development through a series of dynamic processes including the migration of neurons to their final position, the growth and navigation of axons and their synaptic connection with target cells. While the role of chemical cues in guiding neuronal migration and axonal development has been extensively analysed, the contribution of mechanical inputs, such as forces and stiffness, has received far less attention. In this article, we review the in vitro and more recent in vivo studies supporting the notion that mechanical signals are critical for multiple aspects of neuronal circuit assembly, from the emergence of axons to the formation of functional synapses. By combining live imaging approaches with tools designed to measure and manipulate the mechanical environment of neurons, the emerging field of neuromechanics will add a new paradigm in our understanding of neuronal development and potentially inspire novel regenerative therapies.
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Affiliation(s)
- Girisaran Gangatharan
- Sorbonne Université, CNRS UMR 7622, Laboratoire de Biologie du Développement-Institut de Biologie Paris Seine (LBD-IBPS), INSERM, Paris, 75005, France
| | - Sylvie Schneider-Maunoury
- Sorbonne Université, CNRS UMR 7622, Laboratoire de Biologie du Développement-Institut de Biologie Paris Seine (LBD-IBPS), INSERM, Paris, 75005, France
| | - Marie Anne Breau
- Sorbonne Université, CNRS UMR 7622, Laboratoire de Biologie du Développement-Institut de Biologie Paris Seine (LBD-IBPS), INSERM, Paris, 75005, France.,Sorbonne Université, CNRS UMR 8237, Laboratoire Jean Perrin, Paris, 75005, France
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83
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Papandréou MJ, Leterrier C. The functional architecture of axonal actin. Mol Cell Neurosci 2018; 91:151-159. [PMID: 29758267 DOI: 10.1016/j.mcn.2018.05.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/10/2018] [Accepted: 05/11/2018] [Indexed: 11/17/2022] Open
Abstract
The cytoskeleton builds and supports the complex architecture of neurons. It orchestrates the specification, growth, and compartmentation of the axon: axon initial segment, axonal shaft, presynapses. The cytoskeleton must then maintain this intricate architecture for the whole life of its host, but also drive its adaptation to new network demands and changing physiological conditions. Microtubules are readily visible inside axon shafts by electron microscopy, whereas axonal actin study has long been focused on dynamic structures of the axon such as growth cones. Super-resolution microscopy and live-cell imaging have recently revealed new actin-based structures in mature axons: rings, hotspots and trails. This has caused renewed interest for axonal actin, with efforts underway to understand the precise organization and cellular functions of these assemblies. Actin is also present in presynapses, where its arrangement is still poorly defined, and its functions vigorously debated. Here we review the organization of axonal actin, focusing on recent advances and current questions in this rejuvenated field.
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84
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Inner Workings: Uncovering the neuron's internal skeleton. Proc Natl Acad Sci U S A 2018; 113:13931-13933. [PMID: 27930346 DOI: 10.1073/pnas.1617651113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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85
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Park S, Kang W, Kwon YD, Shim J, Kim S, Kaang BK, Hohng S. Superresolution fluorescence microscopy for 3D reconstruction of thick samples. Mol Brain 2018; 11:17. [PMID: 29544505 PMCID: PMC5856285 DOI: 10.1186/s13041-018-0361-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 03/07/2018] [Indexed: 01/07/2023] Open
Abstract
Three-dimensional (3D) reconstruction of thick samples using superresolution fluorescence microscopy remains challenging due to high level of background noise and fast photobleaching of fluorescence probes. We develop superresolution fluorescence microscopy that can reconstruct 3D structures of thick samples with both high localization accuracy and no photobleaching problem. The background noise is reduced by optically sectioning the sample using line-scan confocal microscopy, and the photobleaching problem is overcome by using the DNA-PAINT (Point Accumulation for Imaging in Nanoscale Topography). As demonstrations, we take 3D superresolution images of microtubules of a whole cell, and two-color 3D images of microtubules and mitochondria. We also present superresolution images of chemical synapse of a mouse brain section at different z-positions ranging from 0 μm to 100 μm.
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Affiliation(s)
- Sangjun Park
- Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea.,Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea.,National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
| | - Wooyoung Kang
- Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea.,Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea.,National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea
| | - Yeong-Dae Kwon
- National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea.,Research Institute of Basic Sciences, Seoul National University, Seoul, Republic of Korea
| | - Jaehoon Shim
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Siyong Kim
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Bong-Kiun Kaang
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Sungchul Hohng
- Department of Physics and Astronomy, Seoul National University, Seoul, Republic of Korea. .,Institute of Applied Physics, Seoul National University, Seoul, Republic of Korea. .,National Center of Creative Research Initiatives, Seoul National University, Seoul, Republic of Korea.
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86
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Unsain N, Bordenave MD, Martinez GF, Jalil S, von Bilderling C, Barabas FM, Masullo LA, Johnstone AD, Barker PA, Bisbal M, Stefani FD, Cáceres AO. Remodeling of the Actin/Spectrin Membrane-associated Periodic Skeleton, Growth Cone Collapse and F-Actin Decrease during Axonal Degeneration. Sci Rep 2018; 8:3007. [PMID: 29445221 PMCID: PMC5812996 DOI: 10.1038/s41598-018-21232-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 01/26/2018] [Indexed: 11/09/2022] Open
Abstract
Axonal degeneration occurs in the developing nervous system for the appropriate establishment of mature circuits, and is also a hallmark of diverse neurodegenerative diseases. Despite recent interest in the field, little is known about the changes (and possible role) of the cytoskeleton during axonal degeneration. We studied the actin cytoskeleton in an in vitro model of developmental pruning induced by trophic factor withdrawal (TFW). We found that F-actin decrease and growth cone collapse (GCC) occur early after TFW; however, treatments that prevent axonal fragmentation failed to prevent GCC, suggesting independent pathways. Using super-resolution (STED) microscopy we found that the axonal actin/spectrin membrane-associated periodic skeleton (MPS) abundance and organization drop shortly after deprivation, remaining low until fragmentation. Fragmented axons lack MPS (while maintaining microtubules) and acute pharmacological treatments that stabilize actin filaments prevent MPS loss and protect from axonal fragmentation, suggesting that MPS destruction is required for axon fragmentation to proceed.
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Affiliation(s)
- Nicolas Unsain
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), UNC, Friuli, 2434 - 5016, Córdoba, Argentina. .,Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Martin D Bordenave
- Centro de Investigaciones en Bionanociencias (CIBION)-CONICET, Buenos Aires, Argentina
| | - Gaby F Martinez
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), UNC, Friuli, 2434 - 5016, Córdoba, Argentina.,Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Sami Jalil
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), UNC, Friuli, 2434 - 5016, Córdoba, Argentina.,Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Catalina von Bilderling
- Centro de Investigaciones en Bionanociencias (CIBION)-CONICET, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Federico M Barabas
- Centro de Investigaciones en Bionanociencias (CIBION)-CONICET, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Luciano A Masullo
- Centro de Investigaciones en Bionanociencias (CIBION)-CONICET, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Aaron D Johnstone
- Montreal Neurological Institute, McGill University, Montreal, Canada
| | - Philip A Barker
- Department of Biology, University of British Columbia, Kelowna, BC, Canada
| | - Mariano Bisbal
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), UNC, Friuli, 2434 - 5016, Córdoba, Argentina.,Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Fernando D Stefani
- Centro de Investigaciones en Bionanociencias (CIBION)-CONICET, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alfredo O Cáceres
- Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), UNC, Friuli, 2434 - 5016, Córdoba, Argentina. .,Universidad Nacional de Córdoba, Córdoba, Argentina. .,Instituto Universitario Ciencias Biomédicas de Córdoba (IUCBC), Córdoba, Argentina.
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87
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Berger SL, Leo-Macias A, Yuen S, Khatri L, Pfennig S, Zhang Y, Agullo-Pascual E, Caillol G, Zhu MS, Rothenberg E, Melendez-Vasquez CV, Delmar M, Leterrier C, Salzer JL. Localized Myosin II Activity Regulates Assembly and Plasticity of the Axon Initial Segment. Neuron 2018; 97:555-570.e6. [PMID: 29395909 PMCID: PMC5805619 DOI: 10.1016/j.neuron.2017.12.039] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 08/24/2017] [Accepted: 12/22/2017] [Indexed: 01/08/2023]
Abstract
The axon initial segment (AIS) is the site of action potential generation and a locus of activity-dependent homeostatic plasticity. A multimeric complex of sodium channels, linked via a cytoskeletal scaffold of ankyrin G and beta IV spectrin to submembranous actin rings, mediates these functions. The mechanisms that specify the AIS complex to the proximal axon and underlie its plasticity remain poorly understood. Here we show phosphorylated myosin light chain (pMLC), an activator of contractile myosin II, is highly enriched in the assembling and mature AIS, where it associates with actin rings. MLC phosphorylation and myosin II contractile activity are required for AIS assembly, and they regulate the distribution of AIS components along the axon. pMLC is rapidly lost during depolarization, destabilizing actin and thereby providing a mechanism for activity-dependent structural plasticity of the AIS. Together, these results identify pMLC/myosin II activity as a common link between AIS assembly and plasticity.
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Affiliation(s)
- Stephen L Berger
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | | | - Stephanie Yuen
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Latika Khatri
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Sylvia Pfennig
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | - Yanqing Zhang
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA
| | | | - Ghislaine Caillol
- Aix Marseille Université, CNRS, INP UMR7051, 13344 Cedex 15, Marseille, France
| | - Min-Sheng Zhu
- Model Animal Research Center and MOE Key Laboratory of Model Animal and Disease Study, Nanjing University, Nanjing 210061, China
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, NYU School of Medicine, New York, NY 10016, USA
| | - Carmen V Melendez-Vasquez
- Department of Biological Sciences, Hunter College, New York, NY 10065, USA; Department of Molecular, Cellular, and Developmental Biology, The Graduate Center, The City University of New York, NY 10016, USA
| | - Mario Delmar
- Division of Cardiology, NYU School of Medicine, New York, NY 10016, USA
| | | | - James L Salzer
- Neuroscience Institute and Department of Neuroscience and Physiology, NYU School of Medicine, New York, NY 10016, USA.
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88
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Breau MA, Schneider-Maunoury S. [Stretch-induced axon growth: a universal, yet poorly explored process]. Biol Aujourdhui 2018; 211:215-222. [PMID: 29412131 DOI: 10.1051/jbio/2017028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2017] [Indexed: 12/21/2022]
Abstract
The growth of axons is a key step in neuronal circuit assembly. The axon starts elongating with the migration of its growth cone in response to molecular signals present in the surrounding embryonic tissues. Following the formation of a synapse between the axon and the target cell, the distance which separates the cell body from the synapse continues to increase to accommodate the growth of the organism. This second phase of elongation, which is universal and crucial since it contributes to an important proportion of the final axon size, has been historically referred to as "stretch-induced axon growth". It is indeed likely to result from a mechanical tension generated by the growth of the body, but the underlying mechanisms remain poorly characterized. This article reviews the experimental studies of this process, mainly analysed on cultured neurons so far. The recent development of in vivo imaging techniques and tools to probe and perturb mechanical forces within embryos will shed new light on this universal mode of axonal growth. This knowledge may inspire the design of novel tissue engineering strategies dedicated to brain and spinal cord repair.
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Affiliation(s)
- Marie Anne Breau
- Institut de Biologie Paris-Seine (IBPS), Laboratoire de Biologie du Développement, CNRS UMR7622, INSERM U1156, 75005 Paris, France - Sorbonne Universités, UPMC Université Paris 06, 75005 Paris, France
| | - Sylvie Schneider-Maunoury
- Institut de Biologie Paris-Seine (IBPS), Laboratoire de Biologie du Développement, CNRS UMR7622, INSERM U1156, 75005 Paris, France - Sorbonne Universités, UPMC Université Paris 06, 75005 Paris, France
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89
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Pan L, Yan R, Li W, Xu K. Super-Resolution Microscopy Reveals the Native Ultrastructure of the Erythrocyte Cytoskeleton. Cell Rep 2018; 22:1151-1158. [DOI: 10.1016/j.celrep.2017.12.107] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 11/23/2017] [Accepted: 12/29/2017] [Indexed: 11/30/2022] Open
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90
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Ordonez DG, Lee MK, Feany MB. α-synuclein Induces Mitochondrial Dysfunction through Spectrin and the Actin Cytoskeleton. Neuron 2017; 97:108-124.e6. [PMID: 29249285 DOI: 10.1016/j.neuron.2017.11.036] [Citation(s) in RCA: 165] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2017] [Revised: 10/18/2017] [Accepted: 11/21/2017] [Indexed: 01/20/2023]
Abstract
Genetics and neuropathology strongly link α-synuclein aggregation and neurotoxicity to the pathogenesis of Parkinson's disease and related α-synucleinopathies. Here we describe a new Drosophila model of α-synucleinopathy based on widespread expression of wild-type human α-synuclein, which shows robust neurodegeneration, early-onset locomotor deficits, and abundant α-synuclein aggregation. We use results of forward genetic screening and genetic analysis in our new model to demonstrate that α-synuclein expression promotes reorganization of the actin filament network and consequent mitochondrial dysfunction through altered Drp1 localization. Similar changes are present in a mouse α-synucleinopathy model and in postmortem brain tissue from patients with α-synucleinopathy. Importantly, we provide evidence that the interaction of α-synuclein with spectrin initiates pathological alteration of the actin cytoskeleton and downstream neurotoxicity. These findings suggest new therapeutic approaches for α-synuclein induced neurodegeneration.
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Affiliation(s)
- Dalila G Ordonez
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA; Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Michael K Lee
- Department of Neuroscience, Institute of Translational Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mel B Feany
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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91
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Barabas FM, Masullo LA, Bordenave MD, A Giusti S, Unsain N, Refojo D, Cáceres A, Stefani FD. Automated quantification of protein periodic nanostructures in fluorescence nanoscopy images: abundance and regularity of neuronal spectrin membrane-associated skeleton. Sci Rep 2017; 7:16029. [PMID: 29167561 PMCID: PMC5700202 DOI: 10.1038/s41598-017-16280-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Accepted: 11/08/2017] [Indexed: 12/11/2022] Open
Abstract
Fluorescence nanoscopy imaging permits the observation of periodic supramolecular protein structures in their natural environment, as well as the unveiling of previously unknown protein periodic structures. Deciphering the biological functions of such protein nanostructures requires systematic and quantitative analysis of large number of images under different experimental conditions and specific stimuli. Here we present a method and an open source software for the automated quantification of protein periodic structures in super-resolved images. Its performance is demonstrated by analyzing the abundance and regularity of the spectrin membrane-associated periodic skeleton (MPS) in hippocampal neurons of 2 to 40 days in vitro, imaged by STED and STORM nanoscopy. The automated analysis reveals that both the abundance and the regularity of the MPS increase over time and reach maximum plateau values after 14 DIV. A detailed analysis of the distributions of correlation coefficients provides indication of dynamical assembly and disassembly of the MPS.
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Affiliation(s)
- Federico M Barabas
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2390, C1425FQD, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1 Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Luciano A Masullo
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2390, C1425FQD, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1 Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Martín D Bordenave
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2390, C1425FQD, Buenos Aires, Argentina.,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1 Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina
| | - Sebastián A Giusti
- Laboratorio de Neurobiología Molecular. Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA), CONICET - Partner Institute of the Max Planck Society, Godoy Cruz, 2390, C1425FQD, Buenos Aires, Argentina
| | - Nicolás Unsain
- Laboratorio de Neurobiología, Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC, CONICET), Friuli 2434, 5016, Córdoba, Argentina.,Universidad Nacional de Córdoba (UNC), Av. Haya de la Torre s/n 5000, Córdoba, Argentina
| | - Damián Refojo
- Laboratorio de Neurobiología Molecular. Instituto de Investigación en Biomedicina de Buenos Aires (IBioBA), CONICET - Partner Institute of the Max Planck Society, Godoy Cruz, 2390, C1425FQD, Buenos Aires, Argentina
| | - Alfredo Cáceres
- Laboratorio de Neurobiología, Instituto de Investigación Médica Mercedes y Martín Ferreyra (INIMEC, CONICET), Friuli 2434, 5016, Córdoba, Argentina.,Universidad Nacional de Córdoba (UNC), Av. Haya de la Torre s/n 5000, Córdoba, Argentina
| | - Fernando D Stefani
- Centro de Investigaciones en Bionanociencias (CIBION), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2390, C1425FQD, Buenos Aires, Argentina. .,Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón 1 Ciudad Universitaria, C1428EHA, Buenos Aires, Argentina.
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92
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Pan S, Chan JR. Regulation and dysregulation of axon infrastructure by myelinating glia. J Cell Biol 2017; 216:3903-3916. [PMID: 29114067 PMCID: PMC5716274 DOI: 10.1083/jcb.201702150] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Revised: 10/06/2017] [Accepted: 10/18/2017] [Indexed: 12/21/2022] Open
Abstract
Pan and Chan discuss the role of myelinating glia in axonal development and the impact of demyelination on axon degeneration. Axon loss and neurodegeneration constitute clinically debilitating sequelae in demyelinating diseases such as multiple sclerosis, but the underlying mechanisms of secondary degeneration are not well understood. Myelinating glia play a fundamental role in promoting the maturation of the axon cytoskeleton, regulating axon trafficking parameters, and imposing architectural rearrangements such as the nodes of Ranvier and their associated molecular domains. In the setting of demyelination, these changes may be reversed or persist as maladaptive features, leading to axon degeneration. In this review, we consider recent insights into axon–glial interactions during development and disease to propose that disruption of the cytoskeleton, nodal architecture, and other components of axon infrastructure is a potential mediator of pathophysiological damage after demyelination.
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Affiliation(s)
- Simon Pan
- Department of Neurology, University of California, San Francisco, San Francisco, CA .,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Jonah R Chan
- Department of Neurology, University of California, San Francisco, San Francisco, CA.,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
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93
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94
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Establishing Neuronal Polarity with Environmental and Intrinsic Mechanisms. Neuron 2017; 96:638-650. [DOI: 10.1016/j.neuron.2017.10.021] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Revised: 10/14/2017] [Accepted: 10/15/2017] [Indexed: 12/31/2022]
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95
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β-III-spectrin spinocerebellar ataxia type 5 mutation reveals a dominant cytoskeletal mechanism that underlies dendritic arborization. Proc Natl Acad Sci U S A 2017; 114:E9376-E9385. [PMID: 29078305 DOI: 10.1073/pnas.1707108114] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A spinocerebellar ataxia type 5 (SCA5) L253P mutation in the actin-binding domain (ABD) of β-III-spectrin causes high-affinity actin binding and decreased thermal stability in vitro. Here we show in mammalian cells, at physiological temperature, that the mutant ABD retains high-affinity actin binding. Significantly, we provide evidence that the mutation alters the mobility and recruitment of β-III-spectrin in mammalian cells, pointing to a potential disease mechanism. To explore this mechanism, we developed a Drosophila SCA5 model in which an equivalent mutant Drosophila β-spectrin is expressed in neurons that extend complex dendritic arbors, such as Purkinje cells, targeted in SCA5 pathogenesis. The mutation causes a proximal shift in arborization coincident with decreased β-spectrin localization in distal dendrites. We show that SCA5 β-spectrin dominantly mislocalizes α-spectrin and ankyrin-2, components of the endogenous spectrin cytoskeleton. Our data suggest that high-affinity actin binding by SCA5 β-spectrin interferes with spectrin-actin cytoskeleton dynamics, leading to a loss of a cytoskeletal mechanism in distal dendrites required for dendrite stabilization and arbor outgrowth.
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96
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McDonald NA, Lind AL, Smith SE, Li R, Gould KL. Nanoscale architecture of the Schizosaccharomyces pombe contractile ring. eLife 2017; 6:28865. [PMID: 28914606 PMCID: PMC5779233 DOI: 10.7554/elife.28865] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/14/2017] [Indexed: 12/13/2022] Open
Abstract
The contractile ring is a complex molecular apparatus which physically divides many eukaryotic cells. Despite knowledge of its protein composition, the molecular architecture of the ring is not known. Here we have applied super-resolution microscopy and FRET to determine the nanoscale spatial organization of Schizosaccharomyces pombe contractile ring components relative to the plasma membrane. Similar to other membrane-tethered actin structures, we find proteins localize in specific layers relative to the membrane. The most membrane-proximal layer (0–80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. An intermediate layer (80–160 nm) consists of a network of cytokinesis accessory proteins as well as multiple signaling components which influence cell division. Farthest from the membrane (160–350 nm) we find F-actin, the motor domains of myosins, and a major F-actin crosslinker. Circumferentially within the ring, multiple proteins proximal to the membrane form clusters of different sizes, while components farther from the membrane are uniformly distributed. This comprehensive organizational map provides a framework for understanding contractile ring function.
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Affiliation(s)
- Nathan A McDonald
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Abigail L Lind
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, United States
| | - Sarah E Smith
- Stowers Institute for Medical Research, Kansas City, United States
| | - Rong Li
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, United States
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
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97
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Abstract
Fluorescence nanoscopy uniquely combines minimally invasive optical access to the internal nanoscale structure and dynamics of cells and tissues with molecular detection specificity. While the basic physical principles of 'super-resolution' imaging were discovered in the 1990s, with initial experimental demonstrations following in 2000, the broad application of super-resolution imaging to address cell-biological questions has only more recently emerged. Nanoscopy approaches have begun to facilitate discoveries in cell biology and to add new knowledge. One current direction for method improvement is the ambition to quantitatively account for each molecule under investigation and assess true molecular colocalization patterns via multi-colour analyses. In pursuing this goal, the labelling of individual molecules to enable their visualization has emerged as a central challenge. Extending nanoscale imaging into (sliced) tissue and whole-animal contexts is a further goal. In this Review we describe the successes to date and discuss current obstacles and possibilities for further development.
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98
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Nirschl JJ, Ghiretti AE, Holzbaur ELF. The impact of cytoskeletal organization on the local regulation of neuronal transport. Nat Rev Neurosci 2017; 18:585-597. [PMID: 28855741 DOI: 10.1038/nrn.2017.100] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Neurons are akin to modern cities in that both are dependent on robust transport mechanisms. Like the best mass transit systems, trafficking in neurons must be tailored to respond to local requirements. Neurons depend on both high-speed, long-distance transport and localized dynamics to correctly deliver cargoes and to tune synaptic responses. Here, we focus on the mechanisms that provide localized regulation of the transport machinery, including the cytoskeleton and molecular motors, to yield compartment-specific trafficking in the axon initial segment, axon terminal, dendrites and spines. The synthesis of these mechanisms provides a sophisticated and responsive transit system for the cell.
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Affiliation(s)
- Jeffrey J Nirschl
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 638A Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Amy E Ghiretti
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 638A Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 638A Clinical Research Building, 415 Curie Boulevard, Philadelphia, Pennsylvania 19104, USA
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99
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Structural organization of the actin-spectrin-based membrane skeleton in dendrites and soma of neurons. Proc Natl Acad Sci U S A 2017; 114:E6678-E6685. [PMID: 28739933 DOI: 10.1073/pnas.1705043114] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Actin, spectrin, and associated molecules form a membrane-associated periodic skeleton (MPS) in neurons. In the MPS, short actin filaments, capped by actin-capping proteins, form ring-like structures that wrap around the circumference of neurites, and these rings are periodically spaced along the neurite by spectrin tetramers, forming a quasi-1D lattice structure. This 1D MPS structure was initially observed in axons and exists extensively in axons, spanning nearly the entire axonal shaft of mature neurons. Such 1D MPS was also observed in dendrites, but the extent to which it exists and how it develops in dendrites remain unclear. It is also unclear whether other structural forms of the membrane skeleton are present in neurons. Here, we investigated the spatial organizations of spectrin, actin, and adducin, an actin-capping protein, in the dendrites and soma of cultured hippocampal neurons at different developmental stages, and compared results with those obtained in axons, using superresolution imaging. We observed that the 1D MPS exists in a substantial fraction of dendritic regions in relatively mature neurons, but this structure develops slower and forms with a lower propensity in dendrites than in axons. In addition, we observed that spectrin, actin, and adducin also form a 2D polygonal lattice structure, resembling the expanded erythrocyte membrane skeleton structure, in the somatodendritic compartment. This 2D lattice structure also develops substantially more slowly in the soma and dendrites than the development of the 1D MPS in axons. These results suggest membrane skeleton structures are differentially regulated across different subcompartments of neurons.
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100
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βIII Spectrin Is Necessary for Formation of the Constricted Neck of Dendritic Spines and Regulation of Synaptic Activity in Neurons. J Neurosci 2017; 37:6442-6459. [PMID: 28576936 DOI: 10.1523/jneurosci.3520-16.2017] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/19/2017] [Accepted: 05/19/2017] [Indexed: 01/08/2023] Open
Abstract
Dendritic spines are postsynaptic structures in neurons often having a mushroom-like shape. Physiological significance and cytoskeletal mechanisms that maintain this shape are poorly understood. The spectrin-based membrane skeleton maintains the biconcave shape of erythrocytes, but whether spectrins also determine the shape of nonerythroid cells is less clear. We show that βIII spectrin in hippocampal and cortical neurons from rodent embryos of both sexes is distributed throughout the somatodendritic compartment but is particularly enriched in the neck and base of dendritic spines and largely absent from spine heads. Electron microscopy revealed that βIII spectrin forms a detergent-resistant cytoskeletal network at these sites. Knockdown of βIII spectrin results in a significant decrease in the density of dendritic spines. Surprisingly, the density of presynaptic terminals is not affected by βIII spectrin knockdown. However, instead of making normal spiny synapses, the presynaptic structures in βIII spectrin-depleted neurons make shaft synapses that exhibit increased amplitudes of miniature EPSCs indicative of excessive postsynaptic excitation. Thus, βIII spectrin is necessary for formation of the constricted shape of the spine neck, which in turn controls communication between the synapse and the parent dendrite to prevent excessive excitation. Notably, mutations of SPTNB2 encoding βIII spectrin are associated with neurodegenerative syndromes, spinocerebellar ataxia Type 5, and spectrin-associated autosomal recessive cerebellar ataxia Type 1, but molecular mechanisms linking βIII spectrin functions to neuronal pathologies remain unresolved. Our data suggest that spinocerebellar ataxia Type 5 and spectrin-associated autosomal recessive cerebellar ataxia Type 1 pathology likely arises from poorly controlled synaptic activity that leads to excitotoxicity and neurodegeneration.SIGNIFICANCE STATEMENT Dendritic spines are small protrusions from neuronal dendrites that make synapses with axons of other neurons in the brain. Dendritic spines usually have a mushroom-like shape, which is essential for brain functions, because aberrant spine morphology is associated with many neuropsychiatric disorders. The bulbous head of a mushroom-shaped spine makes the synapse, whereas the narrow neck transmits the incoming signals to the dendrite and supposedly controls the signal propagation. We show that a cytoskeletal protein βIII spectrin plays a key role for the formation of narrow spine necks. In the absence of βIII spectrin, dendritic spines collapse onto dendrites. As a result, synaptic strength exceeds acceptable levels and damages neurons, explaining pathology of human syndromes caused by βIII spectrin mutations.
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