1
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Sabo J, Dujava Zdimalova M, Slater PG, Dostal V, Herynek S, Libusova L, Lowery LA, Braun M, Lansky Z. CKAP5 enables formation of persistent actin bundles templated by dynamically instable microtubules. Curr Biol 2024; 34:260-272.e7. [PMID: 38086388 PMCID: PMC10841699 DOI: 10.1016/j.cub.2023.11.031] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 10/06/2023] [Accepted: 11/14/2023] [Indexed: 01/25/2024]
Abstract
Cytoskeletal rearrangements and crosstalk between microtubules and actin filaments are vital for living organisms. Recently, an abundantly present microtubule polymerase, CKAP5 (XMAP215 homolog), has been reported to play a role in mediating crosstalk between microtubules and actin filaments in the neuronal growth cones. However, the molecular mechanism of this process is unknown. Here, we demonstrate, in a reconstituted system, that CKAP5 enables the formation of persistent actin bundles templated by dynamically instable microtubules. We explain the templating by the difference in CKAP5 binding to microtubules and actin filaments. Binding to the microtubule lattice with higher affinity, CKAP5 enables the formation of actin bundles exclusively on the microtubule lattice, at CKAP5 concentrations insufficient to support any actin bundling in the absence of microtubules. Strikingly, when the microtubules depolymerize, actin bundles prevail at the positions predetermined by the microtubules. We propose that the local abundance of available CKAP5-binding sites in actin bundles allows the retention of CKAP5, resulting in persisting actin bundles. In line with our observations, we found that reducing CKAP5 levels in vivo results in a decrease in actin-microtubule co-localization in growth cones and specifically decreases actin intensity at microtubule plus ends. This readily suggests a mechanism explaining how exploratory microtubules set the positions of actin bundles, for example, in cytoskeleton-rich neuronal growth cones.
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Affiliation(s)
- Jan Sabo
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic; Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University, Hlavova 8, Prague 12800, Czech Republic
| | - Michaela Dujava Zdimalova
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic
| | - Paula G Slater
- Departamento de Ciencias Biológicas y Químicas, Facultad de Medicina y Ciencias, Universidad San Sebastián, Campus Los Leones, Lota 2465, Providencia, Santiago 7510602, Chile
| | - Vojtech Dostal
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Stepan Herynek
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic; Department of Genetics and Microbiology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Lenka Libusova
- Department of Cell Biology, Faculty of Science, Charles University, Vinicna 7, Prague 12800, Czech Republic
| | - Laura A Lowery
- Department of Medicine, Section of Hematology/Oncology, Boston University and Boston Medical Center, Boston, MA 02118, USA
| | - Marcus Braun
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic.
| | - Zdenek Lansky
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, Prumyslova 595, Prague West, Prague 25250, Czech Republic.
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2
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Atkins M, Nicol X, Fassier C. Microtubule remodelling as a driving force of axon guidance and pruning. Semin Cell Dev Biol 2023; 140:35-53. [PMID: 35710759 DOI: 10.1016/j.semcdb.2022.05.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 04/26/2022] [Accepted: 05/31/2022] [Indexed: 01/28/2023]
Abstract
The establishment of neuronal connectivity relies on the microtubule (MT) cytoskeleton, which provides mechanical support, roads for axonal transport and mediates signalling events. Fine-tuned spatiotemporal regulation of MT functions by tubulin post-translational modifications and MT-associated proteins is critical for the coarse wiring and subsequent refinement of neuronal connectivity. The defective regulation of these processes causes a wide range of neurodevelopmental disorders associated with connectivity defects. This review focuses on recent studies unravelling how MT composition, post-translational modifications and associated proteins influence MT functions in axon guidance and/or pruning to build functional neuronal circuits. We here summarise experimental evidence supporting the key role of this network as a driving force for growth cone steering and branch-specific axon elimination. We further provide a global overview of the MT-interactors that tune developing axon behaviours, with a special emphasis on their emerging versatility in the regulation of MT dynamics/structure. Recent studies establishing the key and highly selective role of the tubulin code in the regulation of MT functions in axon pathfinding are also reported. Finally, our review highlights the emerging molecular links between these MT regulation processes and guidance signals that wire the nervous system.
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Affiliation(s)
- Melody Atkins
- INSERM, UMR-S 1270, Institut du Fer à Moulin, Sorbonne Université, F-75005 Paris, France
| | - Xavier Nicol
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012 Paris, France
| | - Coralie Fassier
- Institut de la Vision, Sorbonne Université, INSERM, CNRS, F-75012 Paris, France.
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3
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Akera T. Tubulin post-translational modifications in meiosis. Semin Cell Dev Biol 2023; 137:38-45. [PMID: 34836784 PMCID: PMC9124733 DOI: 10.1016/j.semcdb.2021.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 10/22/2021] [Accepted: 11/14/2021] [Indexed: 11/18/2022]
Abstract
Haploid gametes are produced from diploid parents through meiosis, a process inherent to all sexually reproducing eukaryotes. Faithful chromosome segregation in meiosis is essential for reproductive success, although it is less clear how the meiotic spindle achieves this compared to the mitotic spindle. It is becoming increasingly clear that tubulin post-translational modifications (PTMs) play critical roles in regulating microtubule functions in many biological processes, and meiosis is no exception. Here, I review recent advances in the understanding of tubulin PTMs in meiotic spindles, especially focusing on their roles in spindle integrity, oocyte aging, and non-Mendelian transmission.
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Affiliation(s)
- Takashi Akera
- Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda 20892, MD, USA.
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4
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Iwanski MK, Kapitein LC. Cellular cartography: Towards an atlas of the neuronal microtubule cytoskeleton. Front Cell Dev Biol 2023; 11:1052245. [PMID: 37035244 PMCID: PMC10073685 DOI: 10.3389/fcell.2023.1052245] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 02/28/2023] [Indexed: 04/11/2023] Open
Abstract
Microtubules, one of the major components of the cytoskeleton, play a crucial role during many aspects of neuronal development and function, such as neuronal polarization and axon outgrowth. Consequently, the microtubule cytoskeleton has been implicated in many neurodevelopmental and neurodegenerative disorders. The polar nature of microtubules is quintessential for their function, allowing them to serve as tracks for long-distance, directed intracellular transport by kinesin and dynein motors. Most of these motors move exclusively towards either the plus- or minus-end of a microtubule and some have been shown to have a preference for either dynamic or stable microtubules, those bearing a particular post-translational modification or those decorated by a specific microtubule-associated protein. Thus, it becomes important to consider the interplay of these features and their combinatorial effects on transport, as well as how different types of microtubules are organized in the cell. Here, we discuss microtubule subsets in terms of tubulin isotypes, tubulin post-translational modifications, microtubule-associated proteins, microtubule stability or dynamicity, and microtubule orientation. We highlight techniques used to study these features of the microtubule cytoskeleton and, using the information from these studies, try to define the composition, role, and organization of some of these subsets in neurons.
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5
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Vela-Alcantara AM, Rios-Ramirez A, Santiago-Garcia J, Rodriguez-Alba JC, Tamariz Domínguez E. Modulation of DRG neurons response to semaphorin 3A via substrate stiffness. Cells Dev 2022; 171:203800. [PMID: 35717026 DOI: 10.1016/j.cdev.2022.203800] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 06/10/2022] [Accepted: 06/13/2022] [Indexed: 01/25/2023]
Abstract
Semaphorin 3A (Sema3a) is a chemotropic protein that acts as a neuronal guidance cue and plays a major role in dorsal root ganglion (DRG) sensory neurons projection during embryo development. The present study evaluated the impact of stiffness in the repulsive response of DRG neurons to Sema3a when cultured over substrates of variable stiffness. Stiffness modified DRG neurons morphology and regulated their response to Sema3a, reducing the collapse of growth cones when they were cultured on softer substrates. Sema3a receptors expression was also regulated by stiffness, neuropilin-1 was overexpressed and plexin A4 mRNA was downregulated in stiffer substrates. Cytoskeleton distribution was also modified by stiffness. In softer substrates, βIII-tubulin and actin co-localized up to the leading edge of the growth cones, and as the substrate became stiffer, βIII-tubulin was confined to the transition and peripheral domains of the growth cone. Moreover, a decrease in the α-actinin adaptor protein was also observed in softer substrates. Our results show that substrate stiffness plays an important role in regulating the collapse response to Sema3a and that the modulation of cytoskeleton distribution and Sema3a receptors expression are related to the differential collapse responses of the growth cones.
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Affiliation(s)
- Ana Monserrat Vela-Alcantara
- Instituto de Ciencias de la Salud, Universidad Veracruzana, Av. Luis Castelazo Ayala s/n, 91190 Xalapa, Veracruz, Mexico; Maestría y Doctorado en Ciencias de la Salud, Instituto de Ciencias de la Salud, Universidad Veracruzana, Mexico.
| | - Ariadna Rios-Ramirez
- Instituto de Neurobiología, Universidad Nacional Autónoma de México, Blvd. Juriquilla #3001, 76230 Juriquilla, Querétaro, Mexico.
| | - Juan Santiago-Garcia
- Instituto de Investigaciones Biológicas, Universidad Veracruzana, Av. Luis Castelazo Ayala s/n, 91190 Xalapa, Veracruz, Mexico.
| | - Juan Carlos Rodriguez-Alba
- Instituto de Ciencias de la Salud, Universidad Veracruzana, Av. Luis Castelazo Ayala s/n, 91190 Xalapa, Veracruz, Mexico.
| | - Elisa Tamariz Domínguez
- Instituto de Ciencias de la Salud, Universidad Veracruzana, Av. Luis Castelazo Ayala s/n, 91190 Xalapa, Veracruz, Mexico.
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Sánchez-Huertas C, Herrera E. With the Permission of Microtubules: An Updated Overview on Microtubule Function During Axon Pathfinding. Front Mol Neurosci 2021; 14:759404. [PMID: 34924953 PMCID: PMC8675249 DOI: 10.3389/fnmol.2021.759404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 11/01/2021] [Indexed: 01/27/2023] Open
Abstract
During the establishment of neural circuitry axons often need to cover long distances to reach remote targets. The stereotyped navigation of these axons defines the connectivity between brain regions and cellular subtypes. This chemotrophic guidance process mostly relies on the spatio-temporal expression patterns of extracellular proteins and the selective expression of their receptors in projection neurons. Axon guidance is stimulated by guidance proteins and implemented by neuronal traction forces at the growth cones, which engage local cytoskeleton regulators and cell adhesion proteins. Different layers of guidance signaling regulation, such as the cleavage and processing of receptors, the expression of co-receptors and a wide variety of intracellular cascades downstream of receptors activation, have been progressively unveiled. Also, in the last decades, the regulation of microtubule (MT) assembly, stability and interactions with the submembranous actin network in the growth cone have emerged as crucial effector mechanisms in axon pathfinding. In this review, we will delve into the intracellular signaling cascades downstream of guidance receptors that converge on the MT cytoskeleton of the growing axon. In particular, we will focus on the microtubule-associated proteins (MAPs) network responsible of MT dynamics in the axon and growth cone. Complementarily, we will discuss new evidences that connect defects in MT scaffold proteins, MAPs or MT-based motors and axon misrouting during brain development.
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Affiliation(s)
- Carlos Sánchez-Huertas
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas-Universidad Miguel Hernández (CSIC-UMH), Alicante, Spain
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7
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Hagita A, Wada-Kakuda S, Nobuhara M, Kakuda N, Miyasaka T. Quantitative fractionation of tissue microtubules with distinct biochemical properties reflecting their stability and lability. Biochem Biophys Res Commun 2021; 560:186-191. [PMID: 33992960 DOI: 10.1016/j.bbrc.2021.04.117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 04/27/2021] [Indexed: 10/21/2022]
Abstract
Microtubules form a major cytoskeleton and exhibit dynamic instability through the repetitive polymerization/depolymerization of tubulin dimers. Although microtubule stability should be precisely controlled to maintain various cellular functions, it has been difficult to assess its status in vivo. Here, we propose a tubulin fractionation method reflecting the stability of microtubules in mouse tissues. Analyses of tubulin fractionated by two-step of ultracentrifugation demonstrated three distinct pools of tubulin, that appeared to be stable microtubule, labile microtubule, and free tubulin. Using this method, we were able to show the specific binding of different microtubule-associated proteins onto each pool of microtubules. Also, there were clear differences in the population of stable microtubule among tissues depending on the proliferative capacity of the constituent cells. These findings indicate that this method is useful for broad analysis of microtubule stability in physiological and pathological conditions.
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Affiliation(s)
- Ayaka Hagita
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan; Center for Research in Neurodegenerative Diseases, Doshisha University, Kyoto 610-0394, Japan
| | - Satoko Wada-Kakuda
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan
| | - Mika Nobuhara
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan
| | - Nobuto Kakuda
- Center for Research in Neurodegenerative Diseases, Doshisha University, Kyoto 610-0394, Japan
| | - Tomohiro Miyasaka
- Department of Neuropathology, Faculty of Life and Medical Sciences, Doshisha University, Kyoto, 610-0394, Japan; Center for Research in Neurodegenerative Diseases, Doshisha University, Kyoto 610-0394, Japan.
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8
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Wu D, Jin Y, Shapiro TM, Hinduja A, Baas PW, Tom VJ. Chronic neuronal activation increases dynamic microtubules to enhance functional axon regeneration after dorsal root crush injury. Nat Commun 2020; 11:6131. [PMID: 33257677 PMCID: PMC7705672 DOI: 10.1038/s41467-020-19914-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 11/05/2020] [Indexed: 12/26/2022] Open
Abstract
After a dorsal root crush injury, centrally-projecting sensory axons fail to regenerate across the dorsal root entry zone (DREZ) to extend into the spinal cord. We find that chemogenetic activation of adult dorsal root ganglion (DRG) neurons improves axon growth on an in vitro model of the inhibitory environment after injury. Moreover, repeated bouts of daily chemogenetic activation of adult DRG neurons for 12 weeks post-crush in vivo enhances axon regeneration across a chondroitinase-digested DREZ into spinal gray matter, where the regenerating axons form functional synapses and mediate behavioral recovery in a sensorimotor task. Neuronal activation-mediated axon extension is dependent upon changes in the status of tubulin post-translational modifications indicative of highly dynamic microtubules (as opposed to stable microtubules) within the distal axon, illuminating a novel mechanism underlying stimulation-mediated axon growth. We have identified an effective combinatory strategy to promote functionally-relevant axon regeneration of adult neurons into the CNS after injury.
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Affiliation(s)
- Di Wu
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Ying Jin
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Tatiana M Shapiro
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Abhishek Hinduja
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, USA
| | - Veronica J Tom
- Department of Neurobiology and Anatomy, Marion Murray Spinal Cord Research Center, Drexel University College of Medicine, Philadelphia, PA, USA.
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9
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Erdogan B, St Clair RM, Cammarata GM, Zaccaro T, Ballif BA, Lowery LA. Investigating the impact of the phosphorylation status of tyrosine residues within the TACC domain of TACC3 on microtubule behavior during axon growth and guidance. Cytoskeleton (Hoboken) 2020; 77:277-291. [PMID: 32543081 DOI: 10.1002/cm.21622] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/04/2020] [Accepted: 06/09/2020] [Indexed: 11/10/2022]
Abstract
Axon guidance is a critical process in forming the connections between a neuron and its target. The growth cone steers the growing axon toward the appropriate direction by integrating extracellular guidance cues and initiating intracellular signal transduction pathways downstream of these cues. The growth cone generates these responses by remodeling its cytoskeletal components. Regulation of microtubule dynamics within the growth cone is important for making guidance decisions. TACC3, as a microtubule plus-end binding (EB) protein, modulates microtubule dynamics during axon outgrowth and guidance. We have previously shown that Xenopus laevis embryos depleted of TACC3 displayed spinal cord axon guidance defects, while TACC3-overexpressing spinal neurons showed increased resistance to Slit2-induced growth cone collapse. Tyrosine kinases play an important role in relaying guidance signals to downstream targets during pathfinding events via inducing tyrosine phosphorylation. Here, in order to investigate the mechanism behind TACC3-mediated axon guidance, we examined whether tyrosine residues that are present in TACC3 have any role in regulating TACC3's interaction with microtubules or during axon outgrowth and guidance behaviors. We find that the phosphorylatable tyrosines within the TACC domain are important for the microtubule plus-end tracking behavior of TACC3. Moreover, TACC domain phosphorylation impacts axon outgrowth dynamics such as growth length and growth persistency. Together, our results suggest that tyrosine phosphorylation of TACC3 affects TACC3's microtubule plus-end tracking behavior as well as its ability to mediate axon growth dynamics in cultured embryonic neural tube explants.
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Affiliation(s)
- Burcu Erdogan
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA.,Harvard Department of Stem Cell and Regenerative Biology, Cambridge, Massachusetts, USA
| | - Riley M St Clair
- Department of Biology, University of Vermont, Burlington, Vermont, USA
| | | | - Timothy Zaccaro
- Department of Biology, Boston College, Chestnut Hill, Massachusetts, USA
| | - Bryan A Ballif
- Department of Biology, University of Vermont, Burlington, Vermont, USA
| | - Laura Anne Lowery
- Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
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10
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Terzi A, Suter DM. The role of NADPH oxidases in neuronal development. Free Radic Biol Med 2020; 154:33-47. [PMID: 32370993 DOI: 10.1016/j.freeradbiomed.2020.04.027] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 04/20/2020] [Accepted: 04/27/2020] [Indexed: 12/15/2022]
Abstract
Reactive oxygen species (ROS) are critical for maintaining cellular homeostasis and function when produced in physiological ranges. Important sources of cellular ROS include NADPH oxidases (Nox), which are evolutionary conserved multi-subunit transmembrane proteins. Nox-mediated ROS regulate variety of biological processes including hormone synthesis, calcium signaling, cell migration, and immunity. ROS participate in intracellular signaling by introducing post-translational modifications to proteins and thereby altering their functions. The central nervous system (CNS) expresses different Nox isoforms during both development and adulthood. Here, we review the role of Nox-mediated ROS during CNS development. Specifically, we focus on how individual Nox isoforms contribute to signaling in neural stem cell maintenance and neuronal differentiation, as well as neurite outgrowth and guidance. We also discuss how ROS regulates the organization and dynamics of the actin cytoskeleton in the neuronal growth cone. Finally, we review recent evidence that Nox-derived ROS modulate axonal regeneration upon nervous system injury.
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Affiliation(s)
- Aslihan Terzi
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, 47907, USA
| | - Daniel M Suter
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA; Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, 47907, USA; Bindley Bioscience Center, Purdue University, West Lafayette, IN, 47907, USA.
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11
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Shao Q, Yang T, Huang H, Majumder T, Khot BA, Khouzani MM, Alarmanazi F, Gore YK, Liu G. Disease-associated mutations in human TUBB3 disturb netrin repulsive signaling. PLoS One 2019; 14:e0218811. [PMID: 31226147 PMCID: PMC6588280 DOI: 10.1371/journal.pone.0218811] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Accepted: 06/10/2019] [Indexed: 11/28/2022] Open
Abstract
Missense mutations in the human TUBB3 gene cause a variety of neurological disorders associated with defects in axon guidance and neuronal migration, but the underlying molecular mechanisms are not well understood. Recent studies have shown that direct coupling of dynamic TUBB3 in microtubules with netrin receptors is required for netrin-1-mediated axon guidance, and the interaction of netrin-1 repulsive receptor UNC5C with TUBB3 is involved in netrin-1 mediated axonal repulsion. Here, we report that TUBB3 mutations perturb netrin-1/UNC5C repulsive signaling in the developing nervous system. Among twelve mutants reported in previous studies, five of them show significantly reduced interaction with UNC5C in comparison to the wild-type TUBB3. TUBB3 mutants R262C and R62Q exhibit decreased subcellular colocalization with UNC5C in the peripheral area of the growth cone of primary mouse neurons. Netrin-1 reduces the colocalization of UNC5C with wild-type TUBB3, but not TUBB3 mutants R262C or R62Q, in the growth cone. Results from the in vitro cosedimentation assay indicate that netrin-1 inhibits cosedimentation of UNC5C with polymerized microtubules in primary mouse neurons expressing the wild-type TUBB3, but not R262C or R62Q. Expression of either R262C or R62Q not only blocks netrin-1-induced growth cone collapse and axonal repulsion of primary EGL cells in vitro, but also results in axon projections defects of chicken dorsal root ganglion neurons in ovo. Our study reveals that human TUBB3 mutations specifically perturb netrin-1/UNC5C-mediated repulsion.
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Affiliation(s)
- Qiangqiang Shao
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | - Tao Yang
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | - Huai Huang
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | - Tanushree Majumder
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | - Bhakti Ajit Khot
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | | | - Farrah Alarmanazi
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | - Yasmin K. Gore
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
| | - Guofa Liu
- Department of Biological Sciences, University of Toledo, Toledo, OH, United States of America
- * E-mail:
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12
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Slater PG, Cammarata GM, Samuelson AG, Magee A, Hu Y, Lowery LA. XMAP215 promotes microtubule-F-actin interactions to regulate growth cone microtubules during axon guidance in Xenopus laevis. J Cell Sci 2019; 132:jcs.224311. [PMID: 30890650 DOI: 10.1242/jcs.224311] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 03/08/2019] [Indexed: 12/24/2022] Open
Abstract
It has long been established that neuronal growth cone navigation depends on changes in microtubule (MT) and F-actin architecture downstream of guidance cues. However, the mechanisms by which MTs and F-actin are dually coordinated remain a fundamentally unresolved question. Here, we report that the well-characterized MT polymerase, XMAP215 (also known as CKAP5), plays an important role in mediating MT-F-actin interaction within the growth cone. We demonstrate that XMAP215 regulates MT-F-actin alignment through its N-terminal TOG 1-5 domains. Additionally, we show that XMAP215 directly binds to F-actin in vitro and co-localizes with F-actin in the growth cone periphery. We also find that XMAP215 is required for regulation of growth cone morphology and response to the guidance cue, Ephrin A5. Our findings provide the first strong evidence that XMAP215 coordinates MT and F-actin interaction in vivo We suggest a model in which XMAP215 regulates MT extension along F-actin bundles into the growth cone periphery and that these interactions may be important to control cytoskeletal dynamics downstream of guidance cues. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Paula G Slater
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | | | | | - Alexandra Magee
- Department of Biology, Boston College, Chestnut Hill, MA 02467, USA
| | - Yuhan Hu
- Department of Cell Biology, Yale University, New Haven, CT 06520, USA
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13
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Rink S, Bendella H, Akkin SM, Manthou M, Grosheva M, Angelov DN. Experimental Studies on Facial Nerve Regeneration. Anat Rec (Hoboken) 2019; 302:1287-1303. [DOI: 10.1002/ar.24123] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 10/09/2018] [Accepted: 11/02/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Svenja Rink
- Department of Prosthetic Dentistry, School of Dental and Oral MedicineUniversity of Cologne Cologne Germany
| | - Habib Bendella
- Department of NeurosurgeryUniversity of Witten/Herdecke, Cologne Merheim Medical Center (CMMC) Cologne Germany
| | - Salih Murat Akkin
- Department of Anatomy, School of MedicineSANKO University Gaziantep Turkey
| | - Marilena Manthou
- Department of Histology and EmbryologyAristotle University Thessaloniki Thessaloniki Greece
| | - Maria Grosheva
- Department of Oto‐Rhino‐LaryngologyUniversity of Cologne Cologne Germany
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14
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Ryu JR, Kim JH, Cho HM, Jo Y, Lee B, Joo S, Chae U, Nam Y, Cho IJ, Sun W. A monitoring system for axonal growth dynamics using micropatterns of permissive and Semaphorin 3F chemorepulsive signals. LAB ON A CHIP 2019; 19:291-305. [PMID: 30539180 DOI: 10.1039/c8lc00845k] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Neurons reach their correct targets by directional outgrowth of axons, which is mediated by attractive or repulsive cues. Growing axons occasionally cross a field of repulsive cues and stop at intermediate targets on the journey to their final destination. However, it is not well-understood how individual growth cones make decisions, and pass through repulsive territory to reach their permissive target regions. We developed a microcontact printing culture system that could trap individual axonal tips in a permissive dot area surrounded by the repulsive signal, semaphorin 3F (Sema3F). Axons of rat hippocampal neurons on the Sema3F/PLL dot array extended in the checkboard pattern with a significantly slow growth rate. The detailed analysis of the behaviors of axonal growth cones revealed the saccadic dynamics in the dot array system. The trapped axonal tips in the permissive area underwent growth cone enlargement with remarkably spiky filopodia, promoting their escape from the Sema3F constraints with straight extension of axons. This structured axonal growth on the dot pattern was disrupted by increased inter-dot distance, or perturbing intracellular signaling machineries. These data indicate that axons grow against repulsive signals by jumping over the repulsive cues, depending on contact signals and intracellular milieu. Our study suggests that our dot array culture system can be used as a screening system to easily and efficiently evaluate ECM or small molecule inhibitors interfering growth cone dynamics leading to controlling axonal growth.
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Affiliation(s)
- Jae Ryun Ryu
- Department of Anatomy, Brain Korea 21, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, 136-705, Republic of Korea.
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15
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Kounakis K, Tavernarakis N. The Cytoskeleton as a Modulator of Aging and Neurodegeneration. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1178:227-245. [PMID: 31493230 DOI: 10.1007/978-3-030-25650-0_12] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The cytoskeleton consists of filamentous protein polymers that form organized structures, contributing to a multitude of cell life aspects. It includes three types of polymers: the actin microfilaments, the microtubules and the intermediate filaments. Decades of research have implicated the cytoskeleton in processes that regulate cellular and organismal aging, as well as neurodegeneration associated with injury or neurodegenerative disease, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic Lateral Sclerosis, or Charcot Marie Tooth disease. Here, we provide a brief overview of cytoskeletal structure and function, and discuss experimental evidence linking cytoskeletal function and dynamics with aging and neurodegeneration.
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Affiliation(s)
- Konstantinos Kounakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece.,Department of Basic Sciences, Medical School, University of Crete, Heraklion, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece. .,Department of Basic Sciences, Medical School, University of Crete, Heraklion, Greece.
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16
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Craig EM. Model for Coordination of Microtubule and Actin Dynamics in Growth Cone Turning. Front Cell Neurosci 2018; 12:394. [PMID: 30450038 PMCID: PMC6225807 DOI: 10.3389/fncel.2018.00394] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 10/15/2018] [Indexed: 11/16/2022] Open
Abstract
In the developing nervous system, axons are guided to their synaptic targets by motile structures at the axon tip called growth cones, which reorganize their cytoskeleton in order to steer in response to chemotactic cues. Growth cone motility is mediated by an actin-adhesion “clutch” mechanism, in which mechanical attachment to a substrate, coupled with polarized actin growth, produces leading-edge protrusion. Several studies suggest that dynamic microtubules (MTs) in the growth cone periphery play an essential role in growth cone steering. It is not yet well-understood how the MT cytoskeleton and the dynamic actin-adhesion clutch system are coordinated to promote growth cone navigation. I introduce an experimentally motivated stochastic model of the dynamic reorganization of the growth cone cytoskeleton in response to external guidance cues. According to this model, asymmetric decoupling of MTs from actin retrograde flow leads to a local influx of MTs to the growth cone leading edge, and the leading-edge MT accumulation is amplified by positive feedback between MTs and the actin-adhesion clutch system. Local accumulation of MTs at the leading edge is hypothesized to increase actin adhesion to the substrate, which attenuates actin retrograde flow and promotes leading-edge protrusion. Growth cone alignment with the chemotactic gradient is predicted to be most effective for intermediate levels of sensitivity of the adhesion strength to the presence of leading-edge MTs. Quantitative predictions of the MT distribution and the local rate of retrograde actin flow will allow the hypothetical positive feedback mechanism to be experimentally tested.
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Affiliation(s)
- Erin M Craig
- Department of Physics, Central Washington University, Ellensburg, WA, United States
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17
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Leung KM, Lu B, Wong HHW, Lin JQ, Turner-Bridger B, Holt CE. Cue-Polarized Transport of β-actin mRNA Depends on 3'UTR and Microtubules in Live Growth Cones. Front Cell Neurosci 2018; 12:300. [PMID: 30250426 PMCID: PMC6139529 DOI: 10.3389/fncel.2018.00300] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Accepted: 08/17/2018] [Indexed: 11/13/2022] Open
Abstract
Guidance cues trigger fast responses in axonal growth cones such as directional turning and collapse that require local protein synthesis. An attractive cue-gradient, such as Netrin-1, triggers de novo synthesis of β-actin localized to the near-side compartment of the growth cone that promotes F-actin assembly and attractive steering. How this precise spatial asymmetry in mRNA translation arises across the small expanse of the growth cone is poorly understood. Pre-localized mRNAs in the vicinity of activated receptors could be selectively translated and/or new mRNAs could be trafficked into the area. Here we have performed live imaging of fluorescent-tagged β-actin mRNA to investigate mRNA trafficking dynamics in Xenopus retinal ganglion cell (RGC) axons and growth cones in response to Netrin-1. A Netrin-1 gradient was found to elicit the transport of β-actin mRNA granules to the near-side of growth cones within a 4-7 min window. This polarized mRNA trafficking depended on the 3' untranslated region (UTR) since mRNA-Δ3'UTR mutant failed to exhibit cue-induced localization. Global application of Netrin-1 significantly increased the anterograde movement of β-actin mRNA along axons and also promoted microtubule-dependent mRNA excursions from the central domain of the growth cone into the periphery (filopodia and lamellipodia). Dual channel imaging revealed β-actin mRNA riding behind the microtubule plus-end tracking protein, EB1, in movements along dynamic microtubules into filopodia. The mRNA-EB1 movements were unchanged by a Netrin-1 gradient indicating the dynamic microtubules themselves do not underlie the cue-induced polarity of RNA movement. Finally, fast-moving elongated "worm-like" trains of Cy3-RNA, distinct from mitochondria, were seen transporting RNA along axons in vitro and in vivo suggesting the existence of a novel transport organelle. Overall, the results provide evidence that the axonal trafficking of β-actin mRNA can be regulated by the guidance cue Netrin-1 to transduce the polarity of an extracellular stimulus and that the 3'UTR is essential for this cue-induced regulation.
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Affiliation(s)
| | | | | | | | | | - Christine E. Holt
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
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18
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Kiss A, Fischer I, Kleele T, Misgeld T, Propst F. Neuronal Growth Cone Size-Dependent and -Independent Parameters of Microtubule Polymerization. Front Cell Neurosci 2018; 12:195. [PMID: 30065631 PMCID: PMC6056669 DOI: 10.3389/fncel.2018.00195] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Accepted: 06/17/2018] [Indexed: 01/16/2023] Open
Abstract
Migration and pathfinding of neuronal growth cones during neurite extension is critically dependent on dynamic microtubules. In this study we sought to determine, which aspects of microtubule polymerization relate to growth cone morphology and migratory characteristics. We conducted a multiscale quantitative microscopy analysis using automated tracking of microtubule plus ends in migrating growth cones of cultured murine dorsal root ganglion (DRG) neurons. Notably, this comprehensive analysis failed to identify any changes in microtubule polymerization parameters that were specifically associated with spontaneous extension vs. retraction of growth cones. This suggests that microtubule dynamicity is a basic mechanism that does not determine the polarity of growth cone response but can be exploited to accommodate diverse growth cone behaviors. At the same time, we found a correlation between growth cone size and basic parameters of microtubule polymerization including the density of growing microtubule plus ends and rate and duration of microtubule growth. A similar correlation was observed in growth cones of neurons lacking the microtubule-associated protein MAP1B. However, MAP1B-null growth cones, which are deficient in growth cone migration and steering, displayed an overall reduction in microtubule dynamicity. Our results highlight the importance of taking growth cone size into account when evaluating the influence on growth cone microtubule dynamics of different substrata, guidance factors or genetic manipulations which all can change growth cone morphology and size. The type of large scale multiparametric analysis performed here can help to separate direct effects that these perturbations might have on microtubule dynamics from indirect effects resulting from perturbation-induced changes in growth cone size.
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Affiliation(s)
- Alexa Kiss
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Irmgard Fischer
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
| | - Tatjana Kleele
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich Cluster for Systems Neurology (SyNergy) and German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Thomas Misgeld
- Institute of Neuronal Cell Biology, Technical University of Munich, Munich Cluster for Systems Neurology (SyNergy) and German Center for Neurodegenerative Diseases (DZNE), Munich, Germany
| | - Friedrich Propst
- Department of Biochemistry and Cell Biology, Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter, Vienna, Austria
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19
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Huang H, Yang T, Shao Q, Majumder T, Mell K, Liu G. Human TUBB3 Mutations Disrupt Netrin Attractive Signaling. Neuroscience 2018; 374:155-171. [PMID: 29382549 DOI: 10.1016/j.neuroscience.2018.01.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Revised: 01/16/2018] [Accepted: 01/21/2018] [Indexed: 02/07/2023]
Abstract
Heterozygous missense mutations in human TUBB3 gene result in a spectrum of brain malformations associated with defects in axon guidance, neuronal migration and differentiation. However, the molecular mechanisms underlying mutation-related axon guidance abnormalities are unclear. Recent studies have shown that netrin-1, a canonical guidance cue, induced the interaction of TUBB3 with the netrin receptor deleted in colorectal cancer (DCC). Furthermore, TUBB3 is required for netrin-1-induced axon outgrowth, branching and pathfinding. Here, we provide evidence that TUBB3 mutations impair netrin/DCC signaling in the developing nervous system. The interaction of DCC with most TUBB3 mutants (eight out of twelve) is significantly reduced compared to the wild-type TUBB3. TUBB3 mutants R262C and A302V exhibit decreased subcellular colocalization with DCC in the growth cones of primary neurons. Netrin-1 increases the interaction of endogenous DCC with wild-type human TUBB3, but not R262C or A302V, in primary neurons. Netrin-1 also increases co-sedimentation of DCC with polymerized microtubules (MTs) in primary neurons expressing the wild-type TUBB3, but not R262C or A302V. Expression of either R262C or A302V not only suppresses netrin-1-induced neurite outgrowth, branching and attraction in vitro, but also causes defects in spinal cord commissural axon (CA) projection and pathfinding in ovo. Our study reveals that missense TUBB3 mutations specifically disrupt netrin/DCC-mediated attractive signaling.
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Affiliation(s)
- Huai Huang
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft St., Toledo, OH 43606, USA
| | - Tao Yang
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft St., Toledo, OH 43606, USA
| | - Qiangqiang Shao
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft St., Toledo, OH 43606, USA
| | - Tanushree Majumder
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft St., Toledo, OH 43606, USA
| | - Kristopher Mell
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft St., Toledo, OH 43606, USA
| | - Guofa Liu
- Department of Biological Sciences, University of Toledo, 2801 West Bancroft St., Toledo, OH 43606, USA.
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20
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Austin TO, Matamoros AJ, Friedman JM, Friedman AJ, Nacharaju P, Yu W, Sharp DJ, Baas PW. Nanoparticle Delivery of Fidgetin siRNA as a Microtubule-based Therapy to Augment Nerve Regeneration. Sci Rep 2017; 7:9675. [PMID: 28852085 PMCID: PMC5575010 DOI: 10.1038/s41598-017-10250-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/04/2017] [Indexed: 12/28/2022] Open
Abstract
Microtubule-stabilizing drugs have gained popularity for treating injured adult axons, the rationale being that increased stabilization of microtubules will prevent the axon from retracting and fortify it to grow through inhibitory molecules associated with nerve injury. We have posited that a better approach would be not to stabilize the microtubules, but to increase labile microtubule mass to levels more conducive to axonal growth. Recent work on fetal neurons suggests this can be accomplished using RNA interference to reduce the levels of fidgetin, a microtubule-severing protein. Methods to introduce RNA interference into adult neurons, in vitro or in vivo, have been problematic and not translatable to human patients. Here we show that a novel nanoparticle approach, previously shown to deliver siRNA into tissues and organs, enables siRNA to gain entry into adult rat dorsal root ganglion neurons in culture. Knockdown of fidgetin is partial with this approach, but sufficient to increase the labile microtubule mass of the axon, thereby increasing axonal growth. The increase in axonal growth occurs on both a favorable substrate and a growth-inhibitory molecule associated with scar formation in injured spinal cord. The nanoparticles are readily translatable to in vivo studies on animals and ultimately to clinical applications.
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Affiliation(s)
- Timothy O Austin
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Andrew J Matamoros
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - Joel M Friedman
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Adam J Friedman
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.,Department of Dermatology, George Washington School of Medicine and Health Sciences, Washington, DC, 20037, USA
| | - Parimala Nacharaju
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Wenqian Yu
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA
| | - David J Sharp
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA, 19129, USA.
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21
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Gasperini RJ, Pavez M, Thompson AC, Mitchell CB, Hardy H, Young KM, Chilton JK, Foa L. How does calcium interact with the cytoskeleton to regulate growth cone motility during axon pathfinding? Mol Cell Neurosci 2017; 84:29-35. [PMID: 28765051 DOI: 10.1016/j.mcn.2017.07.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 07/27/2017] [Accepted: 07/28/2017] [Indexed: 02/04/2023] Open
Abstract
The precision with which neurons form connections is crucial for the normal development and function of the nervous system. The development of neuronal circuitry in the nervous system is accomplished by axon pathfinding: a process where growth cones guide axons through the embryonic environment to connect with their appropriate synaptic partners to form functional circuits. Despite intense efforts over many years to understand how this process is regulated, the complete repertoire of molecular mechanisms that govern the growth cone cytoskeleton and hence motility, remain unresolved. A central tenet in the axon guidance field is that calcium signals regulate growth cone behaviours such as extension, turning and pausing by regulating rearrangements of the growth cone cytoskeleton. Here, we provide evidence that not only the amplitude of a calcium signal is critical for growth cone motility but also the source of calcium mobilisation. We provide an example of this idea by demonstrating that manipulation of calcium signalling via L-type voltage gated calcium channels can perturb sensory neuron motility towards a source of netrin-1. Understanding how calcium signals can be transduced to initiate cytoskeletal changes represents a significant gap in our current knowledge of the mechanisms that govern axon guidance, and consequently the formation of functional neural circuits in the developing nervous system.
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Affiliation(s)
- Robert J Gasperini
- School of Medicine, University of Tasmania, Hobart, Tasmania 7001, Australia.
| | - Macarena Pavez
- School of Medicine, University of Tasmania, Hobart, Tasmania 7001, Australia.
| | - Adrian C Thompson
- School of Medicine, University of Tasmania, Hobart, Tasmania 7001, Australia.
| | - Camilla B Mitchell
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7001, Australia.
| | - Holly Hardy
- University of Exeter Medical School, Wellcome Wolfson Centre for Medical Research, Exeter EX2 5DW, United Kingdom.
| | - Kaylene M Young
- Menzies Institute for Medical Research, University of Tasmania, Hobart, Tasmania 7001, Australia.
| | - John K Chilton
- University of Exeter Medical School, Wellcome Wolfson Centre for Medical Research, Exeter EX2 5DW, United Kingdom.
| | - Lisa Foa
- School of Medicine, University of Tasmania, Hobart, Tasmania 7001, Australia.
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22
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Erdogan B, Cammarata GM, Lee EJ, Pratt BC, Francl AF, Rutherford EL, Lowery LA. The microtubule plus-end-tracking protein TACC3 promotes persistent axon outgrowth and mediates responses to axon guidance signals during development. Neural Dev 2017; 12:3. [PMID: 28202041 PMCID: PMC5312526 DOI: 10.1186/s13064-017-0080-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 02/06/2017] [Indexed: 12/14/2022] Open
Abstract
Background Formation of precise neuronal connections requires proper axon guidance. Microtubules (MTs) of the growth cone provide a critical driving force during navigation of the growing ends of axons. Pioneer MTs and their plus-end tracking proteins (+TIPs) are thought to play integrative roles during this navigation. TACC3 is a + TIP that we have previously implicated in regulating MT dynamics within axons. However, the role of TACC3 in axon guidance has not been previously explored. Results Here, we show that TACC3 is required to promote persistent axon outgrowth and prevent spontaneous axon retractions in embryonic Xenopus laevis neurons. We also show that overexpressing TACC3 can counteract the depolymerizing effect of low doses of nocodazole, and that TACC3 interacts with MT polymerase XMAP215 to promote axon outgrowth. Moreover, we demonstrate that manipulation of TACC3 levels interferes with the growth cone response to the axon guidance cue Slit2 ex vivo, and that ablation of TACC3 causes pathfinding defects in axons of developing spinal neurons in vivo. Conclusion Together, our results suggest that by mediating MT dynamics, the + TIP TACC3 is involved in axon outgrowth and pathfinding decisions of neurons during embryonic development.
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Affiliation(s)
- Burcu Erdogan
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | | | - Eric J Lee
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Benjamin C Pratt
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Andrew F Francl
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Erin L Rutherford
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA
| | - Laura Anne Lowery
- Department of Biology, Boston College, Chestnut Hill, MA, 02467, USA.
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23
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Baas PW, Rao AN, Matamoros AJ, Leo L. Stability properties of neuronal microtubules. Cytoskeleton (Hoboken) 2016; 73:442-60. [PMID: 26887570 PMCID: PMC5541393 DOI: 10.1002/cm.21286] [Citation(s) in RCA: 184] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 02/02/2016] [Accepted: 02/12/2016] [Indexed: 01/12/2023]
Abstract
Neurons are terminally differentiated cells that use their microtubule arrays not for cell division but rather as architectural elements required for the elaboration of elongated axons and dendrites. In addition to acting as compression-bearing struts that provide for the shape of the neuron, microtubules also act as directional railways for organelle transport. The stability properties of neuronal microtubules are commonly discussed in the biomedical literature as crucial to the development and maintenance of the nervous system, and have recently gained attention as central to the etiology of neurodegenerative diseases. Drugs that affect microtubule stability are currently under investigation as potential therapies for disease and injury of the nervous system. There is often a lack of consistency, however, in how the issue of microtubule stability is discussed in the literature, and this can affect the design and interpretation of experiments as well as potential therapeutic regimens. Neuronal microtubules are considered to be more stable than microtubules in dividing cells. On average, this is true, but in addition to an abundant stable microtubule fraction in neurons, there is also an abundant labile microtubule fraction. Both are functionally important. Individual microtubules consist of domains that differ in their stability properties, and these domains can also differ markedly in their composition as well as how they interact with various microtubule-related proteins in the neuron. Myriad proteins and pathways have been discussed as potential contributors to microtubule stability in neurons. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Peter W Baas
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA.
| | - Anand N Rao
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Andrew J Matamoros
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
| | - Lanfranco Leo
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, Pennsylvania, USA
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24
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Eira J, Silva CS, Sousa MM, Liz MA. The cytoskeleton as a novel therapeutic target for old neurodegenerative disorders. Prog Neurobiol 2016; 141:61-82. [PMID: 27095262 DOI: 10.1016/j.pneurobio.2016.04.007] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 04/13/2016] [Accepted: 04/13/2016] [Indexed: 12/12/2022]
Abstract
Cytoskeleton defects, including alterations in microtubule stability, in axonal transport as well as in actin dynamics, have been characterized in several unrelated neurodegenerative conditions. These observations suggest that defects of cytoskeleton organization may be a common feature contributing to neurodegeneration. In line with this hypothesis, drugs targeting the cytoskeleton are currently being tested in animal models and in human clinical trials, showing promising effects. Drugs that modulate microtubule stability, inhibitors of posttranslational modifications of cytoskeletal components, specifically compounds affecting the levels of tubulin acetylation, and compounds targeting signaling molecules which regulate cytoskeleton dynamics, constitute the mostly addressed therapeutic interventions aiming at preventing cytoskeleton damage in neurodegenerative disorders. In this review, we will discuss in a critical perspective the current knowledge on cytoskeleton damage pathways as well as therapeutic strategies designed to revert cytoskeleton-related defects mainly focusing on the following neurodegenerative disorders: Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, Amyotrophic Lateral Sclerosis and Charcot-Marie-Tooth Disease.
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Affiliation(s)
- Jessica Eira
- Neurodegeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200 Porto, Portugal
| | - Catarina Santos Silva
- Neurodegeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200 Porto, Portugal
| | - Mónica Mendes Sousa
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200 Porto, Portugal; Nerve Regeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200 Porto, Portugal
| | - Márcia Almeida Liz
- Neurodegeneration Group, IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200 Porto, Portugal; Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200 Porto, Portugal.
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25
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Turney SG, Ahmed M, Chandrasekar I, Wysolmerski RB, Goeckeler ZM, Rioux RM, Whitesides GM, Bridgman PC. Nerve growth factor stimulates axon outgrowth through negative regulation of growth cone actomyosin restraint of microtubule advance. Mol Biol Cell 2016; 27:500-17. [PMID: 26631553 PMCID: PMC4751601 DOI: 10.1091/mbc.e15-09-0636] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/23/2015] [Accepted: 11/24/2015] [Indexed: 01/19/2023] Open
Abstract
Nerve growth factor (NGF) promotes growth, differentiation, and survival of sensory neurons in the mammalian nervous system. Little is known about how NGF elicits faster axon outgrowth or how growth cones integrate and transform signal input to motor output. Using cultured mouse dorsal root ganglion neurons, we found that myosin II (MII) is required for NGF to stimulate faster axon outgrowth. From experiments inducing loss or gain of function of MII, specific MII isoforms, and vinculin-dependent adhesion-cytoskeletal coupling, we determined that NGF causes decreased vinculin-dependent actomyosin restraint of microtubule advance. Inhibition of MII blocked NGF stimulation, indicating the central role of restraint in directed outgrowth. The restraint consists of myosin IIB- and IIA-dependent processes: retrograde actin network flow and transverse actin bundling, respectively. The processes differentially contribute on laminin-1 and fibronectin due to selective actin tethering to adhesions. On laminin-1, NGF induced greater vinculin-dependent adhesion-cytoskeletal coupling, which slowed retrograde actin network flow (i.e., it regulated the molecular clutch). On fibronectin, NGF caused inactivation of myosin IIA, which negatively regulated actin bundling. On both substrates, the result was the same: NGF-induced weakening of MII-dependent restraint led to dynamic microtubules entering the actin-rich periphery more frequently, giving rise to faster elongation.
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Affiliation(s)
- Stephen G Turney
- Center for Brain Science and Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138
| | - Mostafa Ahmed
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
| | - Indra Chandrasekar
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
| | - Robert B Wysolmerski
- Department of Neurobiology and Anatomy, West Virginia University School of Medicine, Morgantown, WV 26506
| | - Zoe M Goeckeler
- Department of Neurobiology and Anatomy, West Virginia University School of Medicine, Morgantown, WV 26506
| | - Robert M Rioux
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - George M Whitesides
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | - Paul C Bridgman
- Department of Neuroscience, Washington University School of Medicine, St. Louis, MO 63110
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26
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Khazaei MR, Girouard MP, Alchini R, Ong Tone S, Shimada T, Bechstedt S, Cowan M, Guillet D, Wiseman PW, Brouhard G, Cloutier JF, Fournier AE. Collapsin response mediator protein 4 regulates growth cone dynamics through the actin and microtubule cytoskeleton. J Biol Chem 2014; 289:30133-43. [PMID: 25225289 PMCID: PMC4208019 DOI: 10.1074/jbc.m114.570440] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Revised: 09/10/2014] [Indexed: 12/22/2022] Open
Abstract
Coordinated control of the growth cone cytoskeleton underlies axon extension and guidance. Members of the collapsin response mediator protein (CRMP) family of cytosolic phosphoproteins regulate the microtubule and actin cytoskeleton, but their roles in regulating growth cone dynamics remain largely unexplored. Here, we examine how CRMP4 regulates the growth cone cytoskeleton. Hippocampal neurons from CRMP4-/- mice exhibited a selective decrease in axon extension and reduced growth cone area, whereas overexpression of CRMP4 enhanced the formation and length of growth cone filopodia. Biochemically, CRMP4 can impact both microtubule assembly and F-actin bundling in vitro. Through a structure function analysis of CRMP4, we found that the effects of CRMP4 on axon growth and growth cone morphology were dependent on microtubule assembly, whereas filopodial extension relied on actin bundling. Intriguingly, anterograde movement of EB3 comets, which track microtubule protrusion, slowed significantly in neurons derived from CRMP4-/- mice, and rescue of microtubule dynamics required CRMP4 activity toward both the actin and microtubule cytoskeleton. Together, this study identified a dual role for CRMP4 in regulating the actin and microtubule growth cone cytoskeleton.
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Affiliation(s)
- Mohamad R Khazaei
- From the Department of Neurology and Neurosurgery, Montréal Neurological Institute, 3801 Rue University, Montréal, Québec H3A 2B4, Canada
| | - Marie-Pier Girouard
- From the Department of Neurology and Neurosurgery, Montréal Neurological Institute, 3801 Rue University, Montréal, Québec H3A 2B4, Canada
| | - Ricardo Alchini
- From the Department of Neurology and Neurosurgery, Montréal Neurological Institute, 3801 Rue University, Montréal, Québec H3A 2B4, Canada
| | - Stephan Ong Tone
- From the Department of Neurology and Neurosurgery, Montréal Neurological Institute, 3801 Rue University, Montréal, Québec H3A 2B4, Canada
| | - Tadayuki Shimada
- Neural Plasticity Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo 156-8506, Japan
| | | | - Mitra Cowan
- Centre de recherche du Centre hospitalier de l'Université de Montréal, Montréal H2X 0A9, Canada
| | | | - Paul W Wiseman
- Department of Physics, McGill University, Montréal H3A 2T8, Canada, Department of Chemistry, McGill University, Montréal H3A 2K6, Canada, and
| | - Gary Brouhard
- Department of Biology, McGill University, Montréal H3G 0B1, Canada
| | - Jean Francois Cloutier
- From the Department of Neurology and Neurosurgery, Montréal Neurological Institute, 3801 Rue University, Montréal, Québec H3A 2B4, Canada
| | - Alyson E Fournier
- From the Department of Neurology and Neurosurgery, Montréal Neurological Institute, 3801 Rue University, Montréal, Québec H3A 2B4, Canada,
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27
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Liu G, Dwyer T. Microtubule dynamics in axon guidance. Neurosci Bull 2014; 30:569-83. [PMID: 24968808 DOI: 10.1007/s12264-014-1444-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Accepted: 04/10/2014] [Indexed: 12/18/2022] Open
Abstract
Precise modulation of the cytoskeleton is involved in a variety of cellular processes including cell division, migration, polarity, and adhesion. In developing post-mitotic neurons, extracellular guidance cues not only trigger signaling cascades that act at a distance to indirectly regulate microtubule distribution, and assembly and disassembly in the growth cone, but also directly modulate microtubule stability and dynamics through coupling of guidance receptors with microtubules to control growth-cone turning. Microtubule-associated proteins including classical microtubule-associated proteins and microtubule plus-end tracking proteins are required for modulating microtubule dynamics to influence growth-cone steering. Multiple key signaling components, such as calcium, small GTPases, glycogen synthase kinase-3β, and c-Jun N-terminal kinase, link upstream signal cascades to microtubule stability and dynamics in the growth cone to control axon outgrowth and projection. Understanding the functions and regulation of microtubule dynamics in the growth cone provides new insights into the molecular mechanisms of axon guidance.
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Affiliation(s)
- Guofa Liu
- Department of Biological Sciences, University of Toledo, Toledo, OH, 43606, USA,
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28
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Silver L, Michael JV, Goldfinger LE, Gallo G. Activation of PI3K and R-Ras signaling promotes the extension of sensory axons on inhibitory chondroitin sulfate proteoglycans. Dev Neurobiol 2014; 74:918-33. [PMID: 24578264 DOI: 10.1002/dneu.22174] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 02/24/2014] [Indexed: 12/22/2022]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) are extracellular inhibitors of axon extension and plasticity, and cause growth cones to exhibit dystrophic behaviors. Phosphoinositide 3-kinase (PI3K) is a lipid kinase activated by axon growth promoting signals. In this study, we used embryonic chicken dorsal root ganglion neurons to determine if CSPGs impair signaling through PI3K. We report that CSPGs inhibit PI3K signaling in axons and growth cones, as evidenced by decreased levels of phosphorylated downstream kinases (Akt and S6). Direct activation of PI3K signaling, using a cell permeable phosphopeptide (PI3Kpep), countered the effects of CSPGs on growth cones and axon extension. Both overnight and acute treatment with PI3Kpep promoted axon extension on CSPG-coated substrates. The R-Ras GTPase is an upstream positive regulator of PI3K signaling. Expression of constitutively active R-Ras promoted axon extension and growth cone elaboration on CSPGs and permissive substrata. In contrast, an N-terminus-deleted constitutively active R-Ras, deficient in PI3K activation, promoted axon extension but not growth cone elaboration on CSPGs and permissive substrata. These data indicate that activation of R-Ras-PI3K signaling may be a viable approach for manipulating axon extension on CSPGs.
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Affiliation(s)
- Lee Silver
- Department of Anatomy and Cell Biology, Temple University School of Medicine, 3500 North Broad St., Philadelphia, Pennsylvania, 19140; Shriners Hospitals Pediatric Research Center, Temple University School of Medicine, Philadelphia, Pennsylvania, 19140
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29
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Gordon-Weeks PR, Fournier AE. Neuronal cytoskeleton in synaptic plasticity and regeneration. J Neurochem 2013; 129:206-12. [PMID: 24147810 DOI: 10.1111/jnc.12502] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Revised: 09/20/2013] [Accepted: 10/17/2013] [Indexed: 11/26/2022]
Abstract
During development, dynamic changes in the axonal growth cone and dendrite are necessary for exploratory movements underlying initial axo-dendritic contact and ultimately the formation of a functional synapse. In the adult central nervous system, an impressive degree of plasticity is retained through morphological and molecular rearrangements in the pre- and post-synaptic compartments that underlie the strengthening or weakening of synaptic pathways. Plasticity is regulated by the interplay of permissive and inhibitory extracellular cues, which signal through receptors at the synapse to regulate the closure of critical periods of developmental plasticity as well as by acute changes in plasticity in response to experience and activity in the adult. The molecular underpinnings of synaptic plasticity are actively studied and it is clear that the cytoskeleton is a key substrate for many cues that affect plasticity. Many of the cues that restrict synaptic plasticity exhibit residual activity in the injured adult CNS and restrict regenerative growth by targeting the cytoskeleton. Here, we review some of the latest insights into how cytoskeletal remodeling affects neuronal plasticity and discuss how the cytoskeleton is being targeted in an effort to promote plasticity and repair following traumatic injury in the central nervous system.
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Affiliation(s)
- Phillip R Gordon-Weeks
- The MRC Centre for Developmental Neurobiology, New Hunt's House, Guy's Campus, King's College London, London, UK
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30
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Baas PW, Ahmad FJ. Beyond taxol: microtubule-based treatment of disease and injury of the nervous system. ACTA ACUST UNITED AC 2013; 136:2937-51. [PMID: 23811322 DOI: 10.1093/brain/awt153] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Contemporary research has revealed a great deal of information on the behaviours of microtubules that underlie critical events in the lives of neurons. Microtubules in the neuron undergo dynamic assembly and disassembly, bundling and splaying, severing, and rapid transport as well as integration with other cytoskeletal elements such as actin filaments. These various behaviours are regulated by signalling pathways that affect microtubule-related proteins such as molecular motor proteins and microtubule severing enzymes, as well as a variety of proteins that promote the assembly, stabilization and bundling of microtubules. In recent years, translational neuroscientists have earmarked microtubules as a promising target for therapy of injury and disease of the nervous system. Proof-of-principle has come mainly from studies using taxol and related drugs to pharmacologically stabilize microtubules in animal models of nerve injury and disease. However, concerns persist that the negative consequences of abnormal microtubule stabilization may outweigh the positive effects. Other potential approaches include microtubule-active drugs with somewhat different properties, but also expanding the therapeutic toolkit to include intervention at the level of microtubule regulatory proteins.
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Affiliation(s)
- Peter W Baas
- 1 Drexel University College of Medicine, Philadelphia, PA, USA
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31
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Xia C, Nguyen M, Garrison AK, Zhao Z, Wang Z, Sutherland C, Ma L. CNP/cGMP signaling regulates axon branching and growth by modulating microtubule polymerization. Dev Neurobiol 2013; 73:673-87. [PMID: 23420620 DOI: 10.1002/dneu.22078] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 02/13/2013] [Accepted: 02/13/2013] [Indexed: 11/06/2022]
Abstract
The peptide hormone CNP has recently been found to positively regulate axon branching and growth via activation of cGMP signaling in embryonic dorsal root ganglion (DRG) neurons, but the cellular mechanisms mediating the regulation of these developmental processes have not been established. In this study, we provide evidence linking CNP/cGMP signaling to microtubule dynamics via the microtubule regulator CRMP2. First, phosphorylation of CRMP2 can be suppressed by cGMP activation in embryonic DRG neurons, and non-phosphorylated CRMP2 promotes axon branching and growth. In addition, real time analysis of growing microtubule ends indicates a similar correlation of CRMP2 phosphorylation and its activity in promoting microtubule polymerization rates and durations in both COS cells and DRG neuron growth cones. Moreover, direct activation of cGMP signaling leads to increased assembly of dynamic microtubules in DRG growth cones. Finally, low doses of a microtubule depolymerization drug nocodazole block CNP/cGMP-dependent axon branching and growth. Taken together, our results support a critical role of microtubule dynamics in mediating CNP/cGMP regulation of axonal development.
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Affiliation(s)
- Caihong Xia
- Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, USA
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32
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Prokop A, Beaven R, Qu Y, Sánchez-Soriano N. Using fly genetics to dissect the cytoskeletal machinery of neurons during axonal growth and maintenance. J Cell Sci 2013; 126:2331-41. [PMID: 23729743 DOI: 10.1242/jcs.126912] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The extension of long slender axons is a key process of neuronal circuit formation, both during brain development and regeneration. For this, growth cones at the tips of axons are guided towards their correct target cells by signals. Growth cone behaviour downstream of these signals is implemented by their actin and microtubule cytoskeleton. In the first part of this Commentary, we discuss the fundamental roles of the cytoskeleton during axon growth. We present the various classes of actin- and microtubule-binding proteins that regulate the cytoskeleton, and highlight the important gaps in our understanding of how these proteins functionally integrate into the complex machinery that implements growth cone behaviour. Deciphering such machinery requires multidisciplinary approaches, including genetics and the use of simple model organisms. In the second part of this Commentary, we discuss how the application of combinatorial genetics in the versatile genetic model organism Drosophila melanogaster has started to contribute to the understanding of actin and microtubule regulation during axon growth. Using the example of dystonin-linked neuron degeneration, we explain how knowledge acquired by studying axonal growth in flies can also deliver new understanding in other aspects of neuron biology, such as axon maintenance in higher animals and humans.
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Affiliation(s)
- Andreas Prokop
- Faculty of Life Sciences, The University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK.
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33
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Mahajan S, Athale CA. Spatial and temporal sensing limits of microtubule polarization in neuronal growth cones by intracellular gradients and forces. Biophys J 2012; 103:2432-45. [PMID: 23260045 DOI: 10.1016/j.bpj.2012.10.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Revised: 10/02/2012] [Accepted: 10/10/2012] [Indexed: 12/22/2022] Open
Abstract
Neuronal growth cones are the most sensitive among eukaryotic cells in responding to directional chemical cues. Although a dynamic microtubule cytoskeleton has been shown to be essential for growth-cone turning, the precise nature of coupling of the spatial cue with microtubule polarization is less understood. Here we present a computational model of microtubule polarization in a turning neuronal growth cone. We explore the limits of directional cues in modifying the spatial polarization of microtubules by testing the role of microtubule dynamics, gradients of regulators, and retrograde forces along filopodia. We analyze the steady state and transition behavior of microtubules on being presented with a directional stimulus. Our model makes novel, to our knowledge, predictions about the minimal angular spread of the chemical signal at the growth cone and the fastest polarization times. A regulatory reaction-diffusion network based on the cyclic phosphorylation-dephosphorylation of a regulator predicts that the receptor-signal magnitude can generate the maximal polarization of microtubules and not feedback loops or amplifications in the network. Using both the phenomenological and network models, we have demonstrated some of the physical limits within which the microtubule polarization system works in turning the neuron.
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Affiliation(s)
- Saurabh Mahajan
- Division of Biology, Indian Institute of Science Education and Research-Pune, Pune, India
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34
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Higurashi M, Iketani M, Takei K, Yamashita N, Aoki R, Kawahara N, Goshima Y. Localized role of CRMP1 and CRMP2 in neurite outgrowth and growth cone steering. Dev Neurobiol 2012; 72:1528-40. [PMID: 22378692 DOI: 10.1002/dneu.22017] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/22/2012] [Accepted: 02/23/2012] [Indexed: 11/10/2022]
Abstract
Collapsin response mediator protein 1 (CRMP1) and CRMP2 have been known as mediators of extracellular guidance cues such as semaphorin 3A and contribute to cytoskeletal reorganization in the axonal pathfinding process. To date, how CRMP1 and CRMP2 focally regulate axonal pathfinding in the growth cone has not been elucidated. To delineate the local functions of these CRMPs, we carried out microscale-chromophore-assisted light inactivation (micro-CALI), which enables investigation of localized molecular functions with highly spatial and temporal resolutions. Inactivation of either CRMP1 or CRMP2 in the neurite shaft led to arrested neurite outgrowth. Micro-CALI of CRMP2 in the central domain of the growth cones consistently arrested neurite outgrowth, whereas micro-CALI of CRMP1 in the same region caused significant lamellipodial retraction, followed by retardation of neurite outgrowth. Focal inactivation of CRMP1 in its half region of the growth cone resulted in the growth cone turning away from the irradiated site. Conversely, focal inactivation of CRMP2 resulted in the growth cone turning toward the irradiated site. These findings suggest different functions for CRMP1 and CRMP2 in growth cone behavior and neurite outgrowth.
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Affiliation(s)
- Masakazu Higurashi
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University Graduate School of Medicine, Japan
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35
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Abstract
While ultimately, focus must be placed on experimentation using adult systems, vastly important clues to regeneration can be found in the study of the embryonic nervous system. In embryonic systems, axonal regeneration is successful before a critical period, and numerous advances have resulted from the study of isolated cells and tissues in vitro. Studies over many decades from the laboratory of Paul C. Letourneau have probed the cellular and molecular phenomena involved in axon outgrowth and guidance in the embryonic central and peripheral nervous system and have laid the framework for many current advances in regeneration research. Letourneau’s pioneering work related to growth cone behavior, guidance, and regeneration has resulted in considerable contributions toward our understanding not only of cellular mechanisms that underlie axon growth, but also of the specific areas of study that require attention to accomplish future breakthroughs. The present article summarizes some of the major contributions from Paul Letourneau and his team in the area of axonal regeneration.
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Affiliation(s)
- Diane M Snow
- Department of Anatomy and Neurobiology, Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, Kentucky 40536, USA.
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36
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The roles of neuronal and glial precursors in overcoming chondroitin sulfate proteoglycan inhibition. Exp Neurol 2012; 235:627-37. [PMID: 22498104 DOI: 10.1016/j.expneurol.2012.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 03/26/2012] [Indexed: 11/23/2022]
Abstract
The extension of axons through the major inhibitory component of the glial scar, chondroitin sulfate proteoglycans (CSPGs), remains a key obstacle for regeneration following spinal cord injury (SCI). We have previously shown that transplants composed of neuronal and glial restricted precursors (NRP and GRP respectively) promote regeneration and connectivity in the injured spinal cord (Bonner et al., 2010, 2011), however, little is known about the properties of these precursors at a cellular level. We now report that NRP-derived neurons, in contrast to dorsal root ganglion (DRG) neurons, have the ability to extend axons and cross over from a permissive substratum (laminin) onto inhibitory CSPG in vitro. Growth cones of neurons derived from NRP, compared to DRG, exhibit significantly lower levels of the CSPG receptors protein tyrosine phosphatase sigma (PTPσ) and leukocyte common antigen-related phosphatase (LAR). GRP-conditioned medium prepared from the same cell densities did not affect the response of primary sensory neurons to CSPG confirming that the ability of NRP-derived neurons to cross onto CSPG is determined intrinsically. However, GRP-conditioned medium collected from high density cultures increased the probability of DRG axons to cross from LN onto CSPG and increased the length of DRG axons extending on CSPG. Collectively, these results suggest that (1) neurons derived from NRPs are intrinsically insensitive to CSPGs due to low levels of receptor expression, and (2) high levels of factors secreted by GRP can reduce the inhibitory effects of CSPG and promote axonal growth. These observations provide mechanistic insights into the specific roles of NRPs and GRPs in promoting regeneration and repair following SCI.
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37
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Yu P, Santiago LY, Katagiri Y, Geller HM. Myosin II activity regulates neurite outgrowth and guidance in response to chondroitin sulfate proteoglycans. J Neurochem 2012; 120:1117-28. [PMID: 22191382 PMCID: PMC3296867 DOI: 10.1111/j.1471-4159.2011.07638.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Chondroitin sulfate proteoglycans (CSPGs) are major components of the extracellular matrix in the CNS that inhibit axonal regeneration after CNS injury. Signaling pathways in neurons triggered by CSPGs are still largely unknown. In this study, using well-characterized in vitro assays for neurite outgrowth and neurite guidance, we demonstrate a major role for myosin II in the response of neurons to CSPGs. We found that the phosphorylation of myosin II regulatory light chains is increased by CSPGs. Specific inhibition of myosin II activity with blebbistatin allows growing neurites to cross onto CSPG-rich areas and increases the length of neurites of neurons growing on CSPGs. Using specific gene knockdown, we demonstrate selective roles for myosin IIA and IIB in these processes. Time lapse microscopy and immunocytochemistry demonstrated that CSPGs also inhibit cell adhesion and cell spreading. Inhibition of myosin II selectively accelerated neurite initiation without altering cell adhesion and spreading on CSPGs.
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Affiliation(s)
- Panpan Yu
- Developmental Neurobiology Section, Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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38
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39
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Hamon L, Savarin P, Curmi PA, Pastré D. Rapid assembly and collective behavior of microtubule bundles in the presence of polyamines. Biophys J 2011; 101:205-16. [PMID: 21723831 DOI: 10.1016/j.bpj.2011.05.022] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 04/21/2011] [Accepted: 05/10/2011] [Indexed: 12/31/2022] Open
Abstract
Microtubules (MTs) are cylindrical cytoskeleton polymers composed of α-β tubulin heterodimers whose dynamic properties are essential to fulfill their numerous cellular functions. In response to spatial confinement, dynamic MTs, even in the absence of protein partners, were shown to self-organize into higher order structures (spindle or striped structures) which lead to interesting dynamical properties (MT oscillations). In this study, we considered the assembly and sensitivity of dynamic MTs when in bundles. To perform this study, spermine, a natural tetravalent polyamine present at high concentrations in all eukaryote cells, was used to trigger MT bundling while preserving MT dynamics. Interestingly, we first show that, near physiological ionic strengths, spermine promotes the bundling of MTs whereas it does not lead to aggregation of free tubulin, which would have been detrimental to MT polymerization. Experimental and theoretical results also indicate that, to obtain a high rate of bundle assembly, bundling should take place at the beginning of assembly when rapid rotational movements of short and newly nucleated MTs are still possible. On the other hand, the bundling process is significantly slowed down for long MTs. Finally, we found that short MT bundles exhibit a higher sensitivity to cold exposure than do isolated MTs. To account for this phenomenon, we suggest that a collective behavior takes place within MT bundles because an MT entering into a phase of shortening could increase the probability of the other MTs in the same bundle to enter into shortening phase due to their close proximity. We then elaborate on some putative applications of our findings to in vivo conditions including neurons.
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Affiliation(s)
- Loïc Hamon
- Laboratoire Structure-Activité des Biomolécules Normales et Pathologiques, Institut National de la Santé et de la Recherche Médicale, U829, and Université Evry-Val d'Essonne, EA3637, Evry, France.
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40
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Kelly TAN, Katagiri Y, Vartanian KB, Kumar P, Chen II, Rosoff WJ, Urbach JS, Geller HM. Localized alteration of microtubule polymerization in response to guidance cues. J Neurosci Res 2011; 88:3024-33. [PMID: 20806407 DOI: 10.1002/jnr.22478] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Inhibition of microtubule dynamic instability prevents growth cone turning in response to guidance cues, yet specific changes in microtubule polymerization as growth cones encounter boundaries have not been investigated. In this study, we examined the rate and direction of microtubule polymerization in response to soluble nerve growth factor (NGF) and immobilized chondroitin sulfate proteoglycans (CSPGs) by expressing enhanced GFP-EB3 in rat pheochromocytoma (PC12) cells. GFP-EB3 comets were monitored in live cells using time-lapse epifluorescent microscopy. With an automated tracking system, the rate of microtubule polymerization was calculated as the frame-to-frame displacement of EB3 comets. Our results demonstrate that the rate of microtubule polymerization is increased following NGF treatment, whereas contact with CSPGs decreases microtubule polymerization rates. This reduction in microtubule polymerization rates was specifically localized to neurites in direct contact with CSPGs and not at noncontacting neurites. Additionally, we found an increase in the percentage of microtubules polymerizing in the retrograde direction in neurites at CSPG boundaries, with a concomitant decrease in the rate of retrograde microtubule polymerization. These results implicate localized changes in microtubule dynamics as an important component of the growth cone response to guidance cues.
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Affiliation(s)
- Terri-Ann N Kelly
- Developmental Neurobiology Section, Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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41
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Skouras E, Ozsoy U, Sarikcioglu L, Angelov DN. Intrinsic and therapeutic factors determining the recovery of motor function after peripheral nerve transection. Ann Anat 2011; 193:286-303. [PMID: 21458252 DOI: 10.1016/j.aanat.2011.02.014] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Revised: 02/03/2011] [Accepted: 02/04/2011] [Indexed: 01/01/2023]
Abstract
Insufficient recovery after peripheral nerve injury has been attributed to (i) poor pathfinding of regrowing axons, (ii) excessive collateral axonal branching at the lesion site and (iii) polyneuronal innervation of the neuromuscular junctions (NMJ). The facial nerve transection model has been used initially to measure restoration of function after varying therapies and to examine the mechanisms underlying their effects. Since it is very difficult to control the navigation of several thousand axons, efforts concentrated on collateral branching and NMJ-polyinnervation. Treatment with antibodies against trophic factors to combat branching improved the precision of reinnervation, but had no positive effects on functional recovery. This suggested that polyneuronal reinnervation--rather than collateral branching--may be the critical limiting factor. The former could be reduced by pharmacological agents known to perturb microtubule assembly and was followed by recovery of function. Because muscle polyinnervation is activity-dependent and can be manipulated, attempts to design a clinically feasible therapy were performed by electrical stimulation or by soft tissue massage. Electrical stimulation applied to the transected facial nerve or to paralysed facial muscles did not improve vibrissal motor performance and failed to diminish polyinnervation. In contrast, gentle stroking of the paralysed muscles (vibrissal, orbicularis oculi, tongue musculature) resulted in full recovery of function. This manual stimulation was also effective after hypoglossal-facial nerve suture and after interpositional nerve grafting, but not after surgical reconstruction of the median nerve. All these findings raise hopes that clinically feasible and effective therapies could be soon designed and tested.
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Affiliation(s)
- Emmanouil Skouras
- Department of Orthopedics and Traumatology, University of Cologne, Joseph-Stelzmann-Strasse 9, Cologne, Germany
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42
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Craddock TJA, Tuszynski JA, Priel A, Freedman H. Microtubule ionic conduction and its implications for higher cognitive functions. J Integr Neurosci 2011; 9:103-22. [PMID: 20589950 DOI: 10.1142/s0219635210002421] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Accepted: 05/21/2010] [Indexed: 11/18/2022] Open
Abstract
The neuronal cytoskeleton has been hypothesized to play a role in higher cognitive functions including learning, memory and consciousness. Experimental evidence suggests that both microtubules and actin filaments act as biological electrical wires that can transmit and amplify electric signals via the flow of condensed ion clouds. The potential transmission of electrical signals via the cytoskeleton is of extreme importance to the electrical activity of neurons in general. In this regard, the unique structure, geometry and electrostatics of microtubules are discussed with the expected impact on their specific functions within the neuron. Electric circuit models of ionic flow along microtubules are discussed in the context of experimental data, and the specific importance of both the tubulin C-terminal tail regions, and the nano-pore openings lining the microtubule wall is elucidated. Overall, these recent results suggest that ions, condensed around the surface of the major filaments of the cytoskeleton, flow along and through microtubules in the presence of potential differences, thus acting as transmission lines propagating intracellular signals in a given cell. The significance of this conductance to the functioning of the electrically active neuron, and to higher cognitive function is also discussed.
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43
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Angelov DN. Factors Limiting Motor Recovery After Facial Nerve Injury. PHYSICAL REHABILITATION OF PARALYSED FACIAL MUSCLES: FUNCTIONAL AND MORPHOLOGICAL CORRELATES 2011. [DOI: 10.1007/978-3-642-18120-7_1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Abstract
Recent evidence suggests that glycogen synthase kinase 3 (GSK3) proteins and their upstream and downstream regulators have key roles in many fundamental processes during neurodevelopment. Disruption of GSK3 signalling adversely affects brain development and is associated with several neurodevelopmental disorders. Here, we discuss the mechanisms by which GSK3 activity is regulated in the nervous system and provide an overview of the recent advances in the understanding of how GSK3 signalling controls neurogenesis, neuronal polarization and axon growth during brain development. These recent advances suggest that GSK3 is a crucial node that mediates various cellular processes that are controlled by multiple signalling molecules--for example, disrupted in schizophrenia 1 (DISC1), partitioning defective homologue 3 (PAR3), PAR6 and Wnt proteins--that regulate neurodevelopment.
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Affiliation(s)
- Eun-Mi Hur
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21287
| | - Feng-Quan Zhou
- Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine, Baltimore, MD 21287
- The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, MD 21287
- Address all correspondence to: Feng-Quan Zhou, Ph.D., 215 Ross Research Building, 720 Rutland Ave, Baltimore, MD 21287. (Phone: 443-2875649, Fax: 410-5026414, )
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45
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Distinct alpha- and beta-tubulin isotypes are required for the positioning, differentiation and survival of neurons: new support for the 'multi-tubulin' hypothesis. Biosci Rep 2010; 30:319-30. [PMID: 20406197 DOI: 10.1042/bsr20100025] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The many functions of the microtubule cytoskeleton are essential for shaping the development and maintaining the operation of the nervous system. With the recent discovery of congenital neurological disorders that result from mutations in genes that encode different alpha- and beta-tubulin isotypes (TUBA1A, TUBB2B, TUBA8 and TUBB3), scientists have a novel paradigm to assess how select perturbations in microtubule function affect a range of cellular processes in humans. Moreover, important phenotypic distinctions found among the syndromes suggest that different tubulin isotypes can be utilized for distinct cellular functions during nervous system development. In the present review, we discuss: (i) the spectrum of congenital nervous system diseases that result from mutations in tubulin and MAPs (microtubule-associated proteins); (ii) the known or putative roles of these proteins during nervous system development; (iii) how the findings collectively support the 'multi-tubulin' hypothesis, which postulates that different tubulin isotypes may be required for specialized microtubule functions.
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46
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Abstract
Interactions between dynamic microtubules and actin filaments are essential to a wide range of cell biological processes including cell division, motility and morphogenesis. In neuronal growth cones, interactions between microtubules and actin filaments in filopodia are necessary for growth cones to make a turn. Growth-cone turning is a fundamental behaviour during axon guidance, as correct navigation of the growth cone through the embryo is required for it to locate an appropriate synaptic partner. Microtubule-actin filament interactions also occur in the transition zone and central domain of the growth cone, where actin arcs exert compressive forces to corral microtubules into the core of the growth cone and thereby facilitate microtubule bundling, a requirement for axon formation. We now have a fairly comprehensive understanding of the dynamic behaviour of the cytoskeleton in growth cones, and the stage is set for discovering the molecular machinery that enables microtubule-actin filament coupling in growth cones, as well as the intracellular signalling pathways that regulate these interactions. Furthermore, recent experiments suggest that microtubule-actin filament interactions might also be important for the formation of dendritic spines from filopodia in mature neurons. Therefore, the mechanisms coupling microtubules to actin filaments in growth-cone turning and dendritic-spine maturation might be conserved.
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Affiliation(s)
- Sara Geraldo
- The MRC Centre for Developmental Neurobiology, New Hunts House, Guy's Campus, King's College London, London SE1 1UL, UK
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47
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Xiong Y, Lee AC, Suter DM, Lee GU. Topography and nanomechanics of live neuronal growth cones analyzed by atomic force microscopy. Biophys J 2009; 96:5060-72. [PMID: 19527666 DOI: 10.1016/j.bpj.2009.03.032] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2008] [Revised: 03/01/2009] [Accepted: 03/26/2009] [Indexed: 10/20/2022] Open
Abstract
Neuronal growth cones are motile structures located at the end of axons that translate extracellular guidance information into directional movements. Despite the important role of growth cones in neuronal development and regeneration, relatively little is known about the topography and mechanical properties of distinct subcellular growth cone regions under live conditions. In this study, we used the AFM to study the P domain, T zone, and C domain of live Aplysia growth cones. The average height of these regions was calculated from contact mode AFM images to be 183 +/- 33, 690 +/- 274, and 1322 +/- 164 nm, respectively. These findings are consistent with data derived from dynamic mode images of live and contact mode images of fixed growth cones. Nano-indentation measurements indicate that the elastic moduli of the C domain and T zone ruffling region ranged between 3-7 and 7-23 kPa, respectively. The range of the measured elastic modulus of the P domain was 10-40 kPa. High resolution images of the P domain suggest its relatively high elastic modulus results from a dense meshwork of actin filaments in lamellipodia and from actin bundles in the filopodia. The increased mechanical stiffness of the P and T domains is likely important to support and transduce tension that develops during growth cone steering.
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Affiliation(s)
- Ying Xiong
- School of Chemical Engineering, Purdue University, West Lafayette, Indiana, USA
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48
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The microtubule network and neuronal morphogenesis: Dynamic and coordinated orchestration through multiple players. Mol Cell Neurosci 2009; 43:15-32. [PMID: 19660553 DOI: 10.1016/j.mcn.2009.07.012] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2009] [Accepted: 07/27/2009] [Indexed: 11/24/2022] Open
Abstract
Nervous system function and plasticity rely on the complex architecture of neuronal networks elaborated during development, when neurons acquire their specific and complex shape. During neuronal morphogenesis, the formation and outgrowth of functionally and structurally distinct axons and dendrites require a coordinated and dynamic reorganization of the microtubule cytoskeleton involving numerous regulators. While most of these factors act directly on microtubules to stabilize them or promote their assembly, depolymerization or fragmentation, others are now emerging as essential regulators of neuronal differentiation by controlling tubulin availability and modulating microtubule dynamics. In this review, we recapitulate how the microtubule network is actively regulated during the successive phases of neuronal morphogenesis, and what are the specific roles of the various microtubule-regulating proteins in that process. We then describe the specific signaling pathways and inter-regulations that coordinate the different activities of these proteins to sustain neuronal development in response to environmental cues.
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49
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Vallee RB, Seale GE, Tsai JW. Emerging roles for myosin II and cytoplasmic dynein in migrating neurons and growth cones. Trends Cell Biol 2009; 19:347-55. [PMID: 19524440 DOI: 10.1016/j.tcb.2009.03.009] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 03/25/2009] [Accepted: 03/31/2009] [Indexed: 11/18/2022]
Abstract
Motor proteins are involved in a wide range of cellular and subcellular movements. Recent studies have implicated two motor proteins in particular, myosin II and cytoplasmic dynein, in diverse aspects of cell migration. This review focuses on emerging roles for these proteins in the nervous system, with particular emphasis on migrating neurons and neuronal growth cones. The former cells exhibit unusual features of centrosome and nuclear movement, whereas growth cones offer an opportunity to evaluate motor protein function in a region of cytoplasm free of these organelles.
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Affiliation(s)
- Richard B Vallee
- Department of Pathology and Cell Biology, Program in Neurobiology and Behavior, Columbia University, College of Physicians and Surgeons, New York, NY 10032, USA.
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Nadar VC, Ketschek A, Myers KA, Gallo G, Baas PW. Kinesin-5 is essential for growth-cone turning. Curr Biol 2008; 18:1972-7. [PMID: 19084405 DOI: 10.1016/j.cub.2008.11.021] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2008] [Revised: 11/05/2008] [Accepted: 11/10/2008] [Indexed: 11/15/2022]
Abstract
Inhibition of kinesin-5, a mitotic motor protein also expressed in neurons, causes axons to grow faster as a result of alterations in the forces on microtubules (MTs) in the axonal shaft. Here, we investigate whether kinesin-5 plays a role in growth-cone guidance. Growth-cone turning requires that MTs in the central (C-) domain enter the peripheral (P-) domain in the direction of the turn. We found that inhibition of kinesin-5 in cultured neurons prevents MTs from polarizing within growth cones and causes them to grow past cues that would normally cause them to turn. We found that kinesin-5 is enriched in the transition (T-) zone of the growth cone and that kinesin-5 is preferentially phosphorylated on the side opposite the invasion of MTs. Moreover, when a growth cone encounters a turning cue, phospho-kinesin-5 polarizes even before the growth cone turns. Additional studies indicate that kinesin-5 works in part by antagonizing cytoplasmic dynein and that these motor-driven forces function together with the dynamic properties of the MTs to determine whether MTs can enter the P-domain. We propose that kinesin-5 permits MTs to selectively invade one side of the growth cone by opposing their entry into the other side.
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Affiliation(s)
- Vidya C Nadar
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
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