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Qin HC, Li FQ, Jin SY, Zhao JS. Retinal displacement after surgery for idiopathic macular hole. Int J Ophthalmol 2024; 17:1545-1556. [PMID: 39156782 PMCID: PMC11286430 DOI: 10.18240/ijo.2024.08.21] [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: 10/27/2023] [Accepted: 03/29/2024] [Indexed: 08/20/2024] Open
Abstract
AIM To review and summarize the mechanism hypothesis, influencing factors and possible consequences of macular retinal displacement after idiopathic macular hole (IMH) surgery. METHODS PubMed and Web of Science database was searched for studies published before April 2023 on "Retinal displacement", "Idiopathic macular holes", and "Macular displacement". RESULTS Recently, more academics have begun to focus on retinal displacement following idiopathic macular holes. They found that internal limiting membrane (ILM) peeling was the main cause of inducing postoperative position shift in the macular region. Moreover, several studies have revealed that the macular hole itself, as well as ILM peeling method, will have an impact on the result. In addition, this phenomenon is related to postoperative changes in macular retinal thickness, cone outer segment tips line recovery, the occurrence of dissociated optic nerve fiber layer (DONFL) and the degree of metamorphopsia. CONCLUSION As a subclinical phenomenon, the clinical significance of postoperative macular displacement cannot be underestimated as it may affect the recovery of anatomy and function.
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Affiliation(s)
- He-Cong Qin
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun 130000, Jilin Province, China
| | - Fu-Qiang Li
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun 130000, Jilin Province, China
| | - Si-Yan Jin
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun 130000, Jilin Province, China
| | - Jin-Song Zhao
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun 130000, Jilin Province, China
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2
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Roth JG, Huang MS, Navarro RS, Akram JT, LeSavage BL, Heilshorn SC. Tunable hydrogel viscoelasticity modulates human neural maturation. SCIENCE ADVANCES 2023; 9:eadh8313. [PMID: 37862423 PMCID: PMC10588948 DOI: 10.1126/sciadv.adh8313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 09/15/2023] [Indexed: 10/22/2023]
Abstract
Human-induced pluripotent stem cells (hiPSCs) have emerged as a promising in vitro model system for studying neurodevelopment. However, current models remain limited in their ability to incorporate tunable biomechanical signaling cues imparted by the extracellular matrix (ECM). The native brain ECM is viscoelastic and stress-relaxing, exhibiting a time-dependent response to an applied force. To recapitulate the remodelability of the neural ECM, we developed a family of protein-engineered hydrogels that exhibit tunable stress relaxation rates. hiPSC-derived neural progenitor cells (NPCs) encapsulated within these gels underwent relaxation rate-dependent maturation. Specifically, NPCs within hydrogels with faster stress relaxation rates extended longer, more complex neuritic projections, exhibited decreased metabolic activity, and expressed higher levels of genes associated with neural maturation. By inhibiting actin polymerization, we observed decreased neuritic projections and a concomitant decrease in neural maturation gene expression. Together, these results suggest that microenvironmental viscoelasticity is sufficient to bias human NPC maturation.
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Affiliation(s)
- Julien G. Roth
- Institute for Stem Cell Biology and Regenerative Medicine, Stanford University School of Medicine, Stanford, CA, USA
- Complex in Vitro Systems, Safety Assessment, Genentech Inc., South San Francisco, CA, USA
| | - Michelle S. Huang
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Renato S. Navarro
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Jason T. Akram
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Bauer L. LeSavage
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Sarah C. Heilshorn
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
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Holland SM, Gallo G. Actin cytoskeletal dynamics do not impose an energy drain on growth cone bioenergetics. J Cell Sci 2023; 136:jcs261356. [PMID: 37534394 PMCID: PMC10445737 DOI: 10.1242/jcs.261356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 07/26/2023] [Indexed: 08/04/2023] Open
Abstract
The regulation of the intracellular level of ATP is a fundamental aspect of bioenergetics. Actin cytoskeletal dynamics have been reported to be an energetic drain in developing neurons and platelets. We addressed the role of actin dynamics in primary embryonic chicken neurons using luciferase assays, and by measurement of the ATP/ADP ratio using the ratiometric reporter PercevalHR and the ATP level using the ratiometric reporter mRuby-iATPSnFR. None of the methods revealed an effect of suppressing actin dynamics on the decline in the neuronal ATP level or the ATP/ADP ratio following shutdown of ATP production. Similarly, we find that treatments that elevate or suppress actin dynamics do not alter the ATP/ADP ratio in growth cones, the subcellular domain with the highest actin dynamics in developing neurons. Collectively, the data indicate that actin cytoskeletal dynamics are not a significant energy drain in developing neurons and that the ATP/ADP ratio is maintained when energy utilization varies. Discrepancies between prior work and the current data are discussed with emphasis on methodology and interpretation of the data.
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Affiliation(s)
- Sabrina M. Holland
- Lewis Katz School of Medicine at Temple University, Department of Neural Sciences, Shriners Pediatric Research Center, 3500 North Broad St, Philadelphia, PA 19140, USA
| | - Gianluca Gallo
- Lewis Katz School of Medicine at Temple University, Department of Neural Sciences, Shriners Pediatric Research Center, 3500 North Broad St, Philadelphia, PA 19140, USA
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Ghose A, Pullarkat P. The role of mechanics in axonal stability and development. Semin Cell Dev Biol 2023; 140:22-34. [PMID: 35786351 PMCID: PMC7615100 DOI: 10.1016/j.semcdb.2022.06.006] [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: 04/04/2022] [Revised: 06/05/2022] [Accepted: 06/13/2022] [Indexed: 01/28/2023]
Abstract
Much of the focus of neuronal cell biology has been devoted to growth cone guidance, synaptogenesis, synaptic activity, plasticity, etc. The axonal shaft too has received much attention, mainly for its astounding ability to transmit action potentials and the transport of material over long distances. For these functions, the axonal cytoskeleton and membrane have been often assumed to play static structural roles. Recent experiments have changed this view by revealing an ultrastructure much richer in features than previously perceived and one that seems to be maintained at a dynamic steady state. The role of mechanics in this is only beginning to be broadly appreciated and appears to involve passive and active modes of coupling different biopolymer filaments, filament turnover dynamics and membrane biophysics. Axons, being unique cellular processes in terms of high aspect ratios and often extreme lengths, also exhibit unique passive mechanical properties that might have evolved to stabilize them under mechanical stress. In this review, we summarize the experiments that have exposed some of these features. It is our view that axonal mechanics deserves much more attention not only due to its significance in the development and maintenance of the nervous system but also due to the susceptibility of axons to injury and neurodegeneration.
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Affiliation(s)
- Aurnab Ghose
- Indian Institute of Science Education and Research, Pune 411 008, India.
| | - Pramod Pullarkat
- Raman Research Institute, C. V. Raman Avenue, Bengaluru 560 080, India.
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5
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Medina-Villalobos N, Avila R, Marsal M, Andilla J, Loza-Álvarez P, Ojeda-Ramírez MM, Tamariz E. Infrared Laser Effects on Cell Projection Depend on Irradiation Intermittence and Cell Activity. Cells 2023; 12:540. [PMID: 36831208 PMCID: PMC9954793 DOI: 10.3390/cells12040540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/06/2023] [Accepted: 01/28/2023] [Indexed: 02/10/2023] Open
Abstract
Highly focused near-infrared (NIR) lasers have been used to induce fibroblast and neuron protrusions in a technique called optical guidance. However, little is known about the biochemical and biophysical effects that the laser provokes in the cell and optimal protocols of stimulation have not yet been established. Using intermittent NIR laser radiation and multivariate time series representations of cell leading edge movement, we analyzed the direction and velocity of cell protrusions. We found that the orientation and advance of PC12 neuron phenotype cells and 3T3 fibroblasts protrusions remain after the laser is turned off, but the observed increase in velocity stops when radiation ceases. For an increase in the speed and distance of cell protrusions by NIR laser irradiation, the cell leading edge needs to be advancing prior to the stimulation, and NIR irradiation does not enable the cell to switch between retracting and advancing states. Using timelapse imaging of actin-GFP, we observed that NIR irradiation induces a faster recruitment of actin, promoting filament formation at the induced cell protrusions. These results provide fresh evidence to understand the phenomenon of the optical guidance of cell protrusions.
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Affiliation(s)
| | - Remy Avila
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México (UNAM), A.P. 1-1010, Juriquilla 76000, Querétaro, Mexico
| | - María Marsal
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Jordi Andilla
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | - Pablo Loza-Álvarez
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain
| | | | - Elisa Tamariz
- Instituto de Ciencias de la Salud, Universidad Veracruzana, Xalapa 91190, Veracruz, Mexico
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6
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Imanaka C, Shimada S, Ito S, Kamada M, Iguchi T, Konishi Y. A model for generating differences in microtubules between axonal branches depending on the distance from terminals. Brain Res 2023; 1799:148166. [PMID: 36402177 DOI: 10.1016/j.brainres.2022.148166] [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: 06/22/2022] [Revised: 09/11/2022] [Accepted: 11/13/2022] [Indexed: 11/18/2022]
Abstract
In the remodeling of axonal arbor, the growth and retraction of branches are differentially regulated within a single axon. Although cell-autonomously generated differences in microtubule (MT) turnover are thought to be involved in selective branch regulation, the cellular system whereby neurons generate differences of MTs between axonal branches has not been clarified. Because MT turnover tends to be slower in longer branches compared with neighboring shorter branches, feedback regulation depending on branch length is thought to be involved. In the present study, we generated a model of MT lifetime in axonal terminal branches by adapting a length-dependent model in which parameters for MT dynamics were constant in the arbor. The model predicted that differences in MT lifetime between neighboring branches could be generated depending on the distance from terminals. In addition, the following points were predicted. Firstly, destabilization of MTs throughout the arbor decreased the differences in MT lifetime between branches. Secondly, differences of MT lifetime existed even before MTs entered the branch point. In axonal MTs in primary neurons, treatment with a low concentration of nocodazole significantly decreased the differences of detyrosination (deTyr) and tyrosination (Tyr) of tubulins, indicators of MT turnover. Expansion microscopy of the axonal shaft before the branch point revealed differences in deTyr/Tyr modification on MTs. Our model recapitulates the differences in MT turnover between branches and provides a feedback mechanism for MT regulation that depends on the axonal arbor geometry.
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Affiliation(s)
- Chiaki Imanaka
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Satoshi Shimada
- Department of Human and Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Shino Ito
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Marina Kamada
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
| | - Tokuichi Iguchi
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan; Department of Nursing, Faculty of Health Science, Fukui Health Science University, Fukui 910-3190, Japan
| | - Yoshiyuki Konishi
- Department of Applied Chemistry and Biotechnology, Artificial Intelligence Systems, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan; Life Science Innovation Center, University of Fukui, Fukui 910-8507, Japan.
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7
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Gallo G. The bioenergetics of neuronal morphogenesis and regeneration: Frontiers beyond the mitochondrion. Dev Neurobiol 2020; 80:263-276. [PMID: 32750228 DOI: 10.1002/dneu.22776] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 07/29/2020] [Accepted: 07/29/2020] [Indexed: 12/27/2022]
Abstract
The formation of axons and dendrites during development, and their regeneration following injury, are energy intensive processes. The underlying assembly and dynamics of the cytoskeleton, axonal transport mechanisms, and extensive signaling networks all rely on ATP and GTP consumption. Cellular ATP is generated through oxidative phosphorylation (OxP) in mitochondria, glycolysis and "regenerative" kinase systems. Recent investigations have focused on the role of the mitochondrion in axonal development and regeneration emphasizing the importance of this organelle and OxP in axon development and regeneration. In contrast, the understanding of alternative sources of ATP in neuronal morphogenesis and regeneration remains largely unexplored. This review focuses on the current state of the field of neuronal bioenergetics underlying morphogenesis and regeneration and considers the literature on the bioenergetics of non-neuronal cell motility to emphasize the potential contributions of non-mitochondrial energy sources.
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Affiliation(s)
- Gianluca Gallo
- Department of Anatomy and Cell Biology, Lewis Katz School of Medicine, Shriners Hospitals Pediatric Research Center, Temple University, Philadelphia, PA, USA
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8
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Abstract
The brain is our most complex organ. During development, neurons extend axons, which may grow over long distances along well-defined pathways to connect to distant targets. Our current understanding of axon pathfinding is largely based on chemical signaling by attractive and repulsive guidance cues. These cues instruct motile growth cones, the leading tips of growing axons, where to turn and where to stop. However, it is not chemical signals that cause motion-motion is driven by forces. Yet our current understanding of the mechanical regulation of axon growth is very limited. In this review, I discuss the origin of the cellular forces controlling axon growth and pathfinding, and how mechanical signals encountered by growing axons may be integrated with chemical signals. This mechanochemical cross talk is an important but often overlooked aspect of cell motility that has major implications for many physiological and pathological processes involving neuronal growth.
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Affiliation(s)
- Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom;
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10
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Ikeno T, Konishi Y. Arp2/3 Is Required for Axonal Arbor Terminal Retraction in Cerebellar Granule Neurons. NEUROCHEM J+ 2020. [DOI: 10.1134/s1819712420010109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Levin E, Leibinger M, Gobrecht P, Hilla A, Andreadaki A, Fischer D. Muscle LIM Protein Is Expressed in the Injured Adult CNS and Promotes Axon Regeneration. Cell Rep 2020; 26:1021-1032.e6. [PMID: 30673598 DOI: 10.1016/j.celrep.2018.12.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 09/05/2018] [Accepted: 12/05/2018] [Indexed: 01/01/2023] Open
Abstract
Muscle LIM protein (MLP) has long been regarded as a muscle-specific protein. Here, we report that MLP expression is induced in adult rat retinal ganglion cells (RGCs) upon axotomy, and its expression is correlated with their ability to regenerate injured axons. Specific knockdown of MLP in RGCs compromises axon regeneration, while overexpression in vivo facilitates optic nerve regeneration and regrowth of sensory neurons without affecting neuronal survival. MLP accumulates in the cell body, the nucleus, and in axonal growth cones, which are significantly enlarged by its overexpression. Only the MLP fraction in growth cones is relevant for promoting axon extension. Additional data suggest that MLP acts as an actin cross-linker, thereby facilitating filopodia formation and increasing growth cone motility. Thus, MLP-mediated effects on actin could become a therapeutic strategy for promoting nerve repair.
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Affiliation(s)
- Evgeny Levin
- Division of Experimental Neurology, Medical Faculty, Heinrich Heine University, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Marco Leibinger
- Department of Cell Physiology, Ruhr University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany; Division of Experimental Neurology, Medical Faculty, Heinrich Heine University, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Philipp Gobrecht
- Department of Cell Physiology, Ruhr University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany; Division of Experimental Neurology, Medical Faculty, Heinrich Heine University, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Alexander Hilla
- Department of Cell Physiology, Ruhr University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany; Division of Experimental Neurology, Medical Faculty, Heinrich Heine University, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Anastasia Andreadaki
- Department of Cell Physiology, Ruhr University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany; Division of Experimental Neurology, Medical Faculty, Heinrich Heine University, Merowingerplatz 1a, 40225 Düsseldorf, Germany
| | - Dietmar Fischer
- Department of Cell Physiology, Ruhr University of Bochum, Universitätsstraße 150, 44780 Bochum, Germany; Division of Experimental Neurology, Medical Faculty, Heinrich Heine University, Merowingerplatz 1a, 40225 Düsseldorf, Germany.
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12
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Meka DP, Scharrenberg R, Calderon de Anda F. Emerging roles of the centrosome in neuronal development. Cytoskeleton (Hoboken) 2020; 77:84-96. [DOI: 10.1002/cm.21593] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 12/16/2019] [Accepted: 01/04/2020] [Indexed: 12/24/2022]
Affiliation(s)
- Durga Praveen Meka
- RG Neuronal Development, Center for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Robin Scharrenberg
- RG Neuronal Development, Center for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐Eppendorf Hamburg Germany
| | - Froylan Calderon de Anda
- RG Neuronal Development, Center for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐Eppendorf Hamburg Germany
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13
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Meka DP, Scharrenberg R, Zhao B, Kobler O, König T, Schaefer I, Schwanke B, Klykov S, Richter M, Eggert D, Windhorst S, Dotti CG, Kreutz MR, Mikhaylova M, Calderon de Anda F. Radial somatic F-actin organization affects growth cone dynamics during early neuronal development. EMBO Rep 2019; 20:e47743. [PMID: 31650708 PMCID: PMC6893363 DOI: 10.15252/embr.201947743] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 09/06/2019] [Accepted: 09/27/2019] [Indexed: 11/16/2022] Open
Abstract
The centrosome is thought to be the major neuronal microtubule-organizing center (MTOC) in early neuronal development, producing microtubules with a radial organization. In addition, albeit in vitro, recent work showed that isolated centrosomes could serve as an actin-organizing center, raising the possibility that neuronal development may, in addition, require a centrosome-based actin radial organization. Here, we report, using super-resolution microscopy and live-cell imaging of cultured rodent neurons, F-actin organization around the centrosome with dynamic F-actin aster-like structures with F-actin fibers extending and retracting actively. Photoactivation/photoconversion experiments and molecular manipulations of F-actin stability reveal a robust flux of somatic F-actin toward the cell periphery. Finally, we show that somatic F-actin intermingles with centrosomal PCM-1 (pericentriolar material 1 protein) satellites. Knockdown of PCM-1 and disruption of centrosomal activity not only affect F-actin dynamics near the centrosome but also in distal growth cones. Collectively, the data show a radial F-actin organization during early neuronal development, which might be a cellular mechanism for providing peripheral regions with a fast and continuous source of actin polymers, hence sustaining initial neuronal development.
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Affiliation(s)
- Durga Praveen Meka
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Robin Scharrenberg
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Bing Zhao
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Oliver Kobler
- Combinatorial Neuroimaging Core Facility (CNI)Leibniz Institute for NeurobiologyMagdeburgGermany
| | - Theresa König
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Irina Schaefer
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Birgit Schwanke
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Sergei Klykov
- Emmy‐Noether Group “Neuronal Protein Transport”Center for Molecular Neurobiology (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Melanie Richter
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Dennis Eggert
- Max Planck Institute for the Structure and Dynamics of MatterHamburgGermany
- Heinrich Pette Institute—Leibniz Institute for Experimental VirologyHamburgGermany
| | - Sabine Windhorst
- Department of Biochemistry and Signal TransductionUniversity Medical Center Hamburg‐EppendorfHamburgGermany
| | - Carlos G Dotti
- Centro de Biología Molecular “Severo Ochoa”CSIC‐UAMMadridSpain
| | - Michael R Kreutz
- RG NeuroplasticityLeibniz Institute for NeurobiologyMagdeburgGermany
- Leibniz Guest Group “Dendritic Organelles and Synaptic Function”Center for Molecular Neurobiology (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Marina Mikhaylova
- Emmy‐Noether Group “Neuronal Protein Transport”Center for Molecular Neurobiology (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
| | - Froylan Calderon de Anda
- RG Neuronal DevelopmentCenter for Molecular Neurobiology Hamburg (ZMNH)University Medical Center Hamburg‐EppendorfHamburgGermany
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14
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Wang W, Halasz E, Townes-Anderson E. Actin Dynamics, Regulated by RhoA-LIMK-Cofilin Signaling, Mediates Rod Photoreceptor Axonal Retraction After Retinal Injury. Invest Ophthalmol Vis Sci 2019; 60:2274-2285. [PMID: 31112612 PMCID: PMC6530517 DOI: 10.1167/iovs.18-26077] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Purpose Retraction of the axon terminals of rod photoreceptors after retinal detachment breaks the first synapse in the visual pathway, resulting in visual impairment. Previous work showed that the mechanism of axonal retraction involves RhoA signaling and its downstream effector LIM Kinase (LIMK) activation. We examined the response of the downstream component cofilin, a direct binding protein of actin filaments, as well as the regulation by RhoA-LIMK-Cofilin signaling of actin assembly/disassembly, in the presynaptic ribbon terminal of injured rod cells. Methods Injury was produced by retinal detachment or rod cell isolation. Detached porcine retina was probed for levels and localization of phosphorylated cofilin with Western blots and confocal microscopy, whereas rod cell cultures of dissociated salamander retina were examined for filamentous actin assembly/disassembly with a barbed end assay and phalloidin staining. Results A detachment increased phosphorylation of cofilin in retinal explants; phosphorylation occurred in rod terminals in sections of detached retina. Isolation of rod cells resulted in axon retraction accompanied by an increase in actin barbed ends and a decrease in net filament labeling. All changes were significantly reduced by either Rho kinase (ROCK) or LIMK inhibition, using Y27632 or BMS-5, respectively. Cytochalasin D also reduced retraction and stabilized filaments in isolated rod cells. Conclusions These results indicate that actin depolymerization via activation of RhoA downstream kinases and cofilin contributes to axon retraction. Preventing depolymerization, in addition to actomyosin contraction, may stabilize ribbon synapses after trauma.
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Affiliation(s)
- Weiwei Wang
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, Rutgers, The State University of New Jersey, Newark, New Jersey, United States
| | - Eva Halasz
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, Rutgers, The State University of New Jersey, Newark, New Jersey, United States
| | - Ellen Townes-Anderson
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Graduate School of Biomedical Sciences, Rutgers Biomedical and Health Sciences, Rutgers, The State University of New Jersey, Newark, New Jersey, United States
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15
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Barros Ribeiro da Silva V, Porcionatto M, Toledo Ribas V. The Rise of Molecules Able To Regenerate the Central Nervous System. J Med Chem 2019; 63:490-511. [PMID: 31518122 DOI: 10.1021/acs.jmedchem.9b00863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Injury to the adult central nervous system (CNS) usually leads to permanent deficits of cognitive, sensory, and/or motor functions. The failure of axonal regeneration in the damaged CNS limits functional recovery. The lack of information concerning the biological mechanism of axonal regeneration and its complexity has delayed the process of drug discovery for many years compared to other drug classes. Starting in the early 2000s, the ability of many molecules to stimulate axonal regrowth was evaluated through automated screening techniques; many hits and some new mechanisms involved in axonal regeneration were identified. In this Perspective, we discuss the rise of the CNS regenerative drugs, the main biological techniques used to test these drug candidates, some of the most important screens performed so far, and the main challenges following the identification of a drug that is able to induce axonal regeneration in vivo.
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Affiliation(s)
| | - Marimélia Porcionatto
- Universidade Federal de São Paulo , Escola Paulista de Medicina, Laboratório de Neurobiologia Molecular, Departmento de Bioquímica , Rua Pedro de Toledo, 669 - third floor, 04039-032 São Paulo , São Paolo , Brazil
| | - Vinicius Toledo Ribas
- Universidade Federal de Minas Gerais , Instituto de Ciências Biológicas, Departamento de Morfologia, Laboratório de Neurobiologia Av. Antônio Carlos, 6627, room O3-245 , - Campus Pampulha, 31270-901 , Belo Horizonte , Minas Gerais , Brazil
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16
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van de Willige D, Hummel JJ, Alkemade C, Kahn OI, Au FK, Qi RZ, Dogterom M, Koenderink GH, Hoogenraad CC, Akhmanova A. Cytolinker Gas2L1 regulates axon morphology through microtubule-modulated actin stabilization. EMBO Rep 2019; 20:e47732. [PMID: 31486213 PMCID: PMC6831992 DOI: 10.15252/embr.201947732] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 08/07/2019] [Accepted: 08/15/2019] [Indexed: 12/30/2022] Open
Abstract
Crosstalk between the actin and microtubule cytoskeletons underlies cellular morphogenesis. Interactions between actin filaments and microtubules are particularly important for establishing the complex polarized morphology of neurons. Here, we characterized the neuronal function of growth arrest‐specific 2‐like 1 (Gas2L1), a protein that can directly bind to actin, microtubules and microtubule plus‐end‐tracking end binding proteins. We found that Gas2L1 promotes axon branching, but restricts axon elongation in cultured rat hippocampal neurons. Using pull‐down experiments and in vitro reconstitution assays, in which purified Gas2L1 was combined with actin and dynamic microtubules, we demonstrated that Gas2L1 is autoinhibited. This autoinhibition is relieved by simultaneous binding to actin filaments and microtubules. In neurons, Gas2L1 primarily localizes to the actin cytoskeleton and functions as an actin stabilizer. The microtubule‐binding tail region of Gas2L1 directs its actin‐stabilizing activity towards the axon. We propose that Gas2L1 acts as an actin regulator, the function of which is spatially modulated by microtubules.
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Affiliation(s)
- Dieudonnée van de Willige
- Department of Biology, Cell Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Jessica Ja Hummel
- Department of Biology, Cell Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Celine Alkemade
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands.,Living Matter Department, AMOLF, Amsterdam, The Netherlands
| | - Olga I Kahn
- Department of Biology, Cell Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Franco Kc Au
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Robert Z Qi
- Division of Life Science and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Marileen Dogterom
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, Delft, The Netherlands
| | | | - Casper C Hoogenraad
- Department of Biology, Cell Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
| | - Anna Akhmanova
- Department of Biology, Cell Biology, Faculty of Science, Utrecht University, Utrecht, The Netherlands
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17
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Datar A, Ameeramja J, Bhat A, Srivastava R, Mishra A, Bernal R, Prost J, Callan-Jones A, Pullarkat PA. The Roles of Microtubules and Membrane Tension in Axonal Beading, Retraction, and Atrophy. Biophys J 2019; 117:880-891. [PMID: 31427070 DOI: 10.1016/j.bpj.2019.07.046] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/23/2019] [Accepted: 07/26/2019] [Indexed: 02/02/2023] Open
Abstract
Axonal beading, or the formation of a series of swellings along the axon, and retraction are commonly observed shape transformations that precede axonal atrophy in Alzheimer's disease, Parkinson's disease, and other neurodegenerative conditions. The mechanisms driving these morphological transformations are poorly understood. Here, we report controlled experiments that can induce either beading or retraction and follow the time evolution of these responses. By making quantitative analysis of the shape modes under different conditions, measurement of membrane tension, and using theoretical considerations, we argue that membrane tension is the main driving force that pushes cytosol out of the axon when microtubules are degraded, causing axonal thinning. Under pharmacological perturbation, atrophy is always retrograde, and this is set by a gradient in the microtubule stability. The nature of microtubule depolymerization dictates the type of shape transformation, vis-à-vis beading or retraction. Elucidating the mechanisms of these shape transformations may facilitate development of strategies to prevent or arrest axonal atrophy due to neurodegenerative conditions.
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Affiliation(s)
| | | | - Alka Bhat
- Raman Research Institute, Bengaluru, India
| | | | | | - Roberto Bernal
- Departamento de Física, SMAT-C, Universidad de Santiago de Chile, Santiago, Chile
| | - Jacques Prost
- Laboratoire Physico Chimie Curie, Institut Curie, 10 PSL Research University, CNRS UMR168, Paris, France; Mechanobiology Institute, National University of Singapore, Singapore
| | - Andrew Callan-Jones
- Laboratoire Matière et Systèmes Complexes, Université Paris Diderot, Paris, France.
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18
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Shao X, You R, Hui TH, Fang C, Gong Z, Yan Z, Chang RCC, Shenoy VB, Lin Y. Tension- and Adhesion-Regulated Retraction of Injured Axons. Biophys J 2019; 117:193-202. [PMID: 31278003 DOI: 10.1016/j.bpj.2019.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 05/27/2019] [Accepted: 06/14/2019] [Indexed: 12/16/2022] Open
Abstract
Damage-induced retraction of axons during traumatic brain injury is believed to play a key role in the disintegration of the neural network and to eventually lead to severe symptoms such as permanent memory loss and emotional disturbances. However, fundamental questions such as how axon retraction progresses and what physical factors govern this process still remain unclear. Here, we report a combined experimental and modeling study to address these questions. Specifically, a sharp atomic force microscope probe was used to transect axons and trigger their retraction in a precisely controlled manner. Interestingly, we showed that the retracting motion of a well-developed axon can be arrested by strong cell-substrate attachment. However, axon retraction was found to be retriggered if a second transection was conducted, albeit with a lower shrinking amplitude. Furthermore, disruption of the actin cytoskeleton or cell-substrate adhesion significantly altered the retracting dynamics of injured axons. Finally, a mathematical model was developed to explain the observed injury response of neural cells in which the retracting motion was assumed to be driven by the pre-tension in the axon and progress against neuron-substrate adhesion as well as the viscous resistance of the cell. Using realistic parameters, model predictions were found to be in good agreement with our observations under a variety of experimental conditions. By revealing the essential physics behind traumatic axon retraction, findings here could provide insights on the development of treatment strategies for axonal injury as well as its possible interplay with other neurodegenerative diseases.
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Affiliation(s)
- Xueying Shao
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong, China
| | - Ran You
- Laboratory of Neurodegenerative Diseases, School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Tsz Hin Hui
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong, China
| | - Chao Fang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong, China
| | - Ze Gong
- Center for Engineering Mechanobiology and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Zishen Yan
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong, China
| | - Raymond Chuen Chung Chang
- Laboratory of Neurodegenerative Diseases, School of Biomedical Sciences, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Vivek B Shenoy
- Center for Engineering Mechanobiology and Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania.
| | - Yuan Lin
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China; HKU-Shenzhen Institute of Research and Innovation, Shenzhen, Guangdong, China.
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19
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Miller KE, Suter DM. An Integrated Cytoskeletal Model of Neurite Outgrowth. Front Cell Neurosci 2018; 12:447. [PMID: 30534055 PMCID: PMC6275320 DOI: 10.3389/fncel.2018.00447] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Accepted: 11/07/2018] [Indexed: 12/27/2022] Open
Abstract
Neurite outgrowth underlies the wiring of the nervous system during development and regeneration. Despite a significant body of research, the underlying cytoskeletal mechanics of growth and guidance are not fully understood, and the relative contributions of individual cytoskeletal processes to neurite growth are controversial. Here, we review the structural organization and biophysical properties of neurons to make a semi-quantitative comparison of the relative contributions of different processes to neurite growth. From this, we develop the idea that neurons are active fluids, which generate strong contractile forces in the growth cone and weaker contractile forces along the axon. As a result of subcellular gradients in forces and material properties, actin flows rapidly rearward in the growth cone periphery, and microtubules flow forward in bulk along the axon. With this framework, an integrated model of neurite outgrowth is proposed that hopefully will guide new approaches to stimulate neuronal growth.
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Affiliation(s)
- Kyle E Miller
- Department of Integrative Biology, Michigan State University, East Lansing, MI, United States
| | - Daniel M Suter
- Department of Biological Sciences, Purdue University, West Lafayette, IN, United States.,Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN, United States.,Bindley Bioscience Center, Purdue University, West Lafayette, IN, United States.,Birck Nanotechnology Center, Purdue University, West Lafayette, IN, United States
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20
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Collinson JM, Lindström NO, Neves C, Wallace K, Meharg C, Charles RH, Ross ZK, Fraser AM, Mbogo I, Oras K, Nakamoto M, Barker S, Duce S, Miedzybrodzka Z, Vargesson N. The developmental and genetic basis of 'clubfoot' in the peroneal muscular atrophy mutant mouse. Development 2018; 145:145/3/dev160093. [PMID: 29439133 DOI: 10.1242/dev.160093] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 12/28/2017] [Indexed: 12/19/2022]
Abstract
Genetic factors underlying the human limb abnormality congenital talipes equinovarus ('clubfoot') remain incompletely understood. The spontaneous autosomal recessive mouse 'peroneal muscular atrophy' mutant (PMA) is a faithful morphological model of human clubfoot. In PMA mice, the dorsal (peroneal) branches of the sciatic nerves are absent. In this study, the primary developmental defect was identified as a reduced growth of sciatic nerve lateral motor column (LMC) neurons leading to failure to project to dorsal (peroneal) lower limb muscle blocks. The pma mutation was mapped and a candidate gene encoding LIM-domain kinase 1 (Limk1) identified, which is upregulated in mutant lateral LMC motor neurons. Genetic and molecular analyses showed that the mutation acts in the EphA4-Limk1-Cfl1/cofilin-actin pathway to modulate growth cone extension/collapse. In the chicken, both experimental upregulation of Limk1 by electroporation and pharmacological inhibition of actin turnover led to defects in hindlimb spinal motor neuron growth and pathfinding, and mimicked the clubfoot phenotype. The data support a neuromuscular aetiology for clubfoot and provide a mechanistic framework to understand clubfoot in humans.
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Affiliation(s)
- J Martin Collinson
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Nils O Lindström
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Carlos Neves
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Karen Wallace
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Caroline Meharg
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Rebecca H Charles
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Zoe K Ross
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Amy M Fraser
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Ivan Mbogo
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Kadri Oras
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Masaru Nakamoto
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Simon Barker
- Royal Aberdeen Children's Hospital, Foresterhill, Aberdeen AB25 2ZN, UK
| | - Suzanne Duce
- School of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Zosia Miedzybrodzka
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
| | - Neil Vargesson
- School of Medicine, Medical Sciences and Nutrition, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
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21
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Ohta K, Sato A, Senda N, Fukui E. Displacement of fovea toward optic disk after macular hole surgery with internal limiting membrane peeling. Int Med Case Rep J 2017; 10:345-348. [PMID: 29081675 PMCID: PMC5652921 DOI: 10.2147/imcrj.s148712] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to demonstrate a displacement of the foveal depression toward the optic disk after idiopathic macular hole (MH) surgery with internal limiting membrane (ILM) peeling. Methods Two patients with a unilateral MH developed an MH in the fellow eyes. Vitrectomy with ILM peeling was performed on the fellow eye to close the MH. Images of spectral-domain optical coherence tomography (SD-OCT) were used to measure the disk-to-fovea distances pre MH formation, after MH formation, and 6 months after the closure of the MH. Results The disk-to-fovea distance was shorter at 6 months than after the development of the MH (4,109 µm and 4,174 µm in Case 1 and 4,001 µm and 4,051 µm in Case 2). Conclusion These results indicate that the fovea moves nasally after the MH surgery with ILM peeling.
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Affiliation(s)
- Kouichi Ohta
- Department of Ophthalmology, Matsumoto Dental University, Shiojiri, Nagano, Japan
| | - Atsuko Sato
- Department of Ophthalmology, Matsumoto Dental University, Shiojiri, Nagano, Japan
| | - Nami Senda
- Department of Ophthalmology, Matsumoto Dental University, Shiojiri, Nagano, Japan
| | - Emi Fukui
- Department of Ophthalmology, Matsumoto Dental University, Shiojiri, Nagano, Japan
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22
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Hill CE. A view from the ending: Axonal dieback and regeneration following SCI. Neurosci Lett 2017; 652:11-24. [DOI: 10.1016/j.neulet.2016.11.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 10/20/2016] [Accepted: 11/01/2016] [Indexed: 12/22/2022]
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23
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Hensel N, Claus P. The Actin Cytoskeleton in SMA and ALS: How Does It Contribute to Motoneuron Degeneration? Neuroscientist 2017; 24:54-72. [PMID: 28459188 DOI: 10.1177/1073858417705059] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) are neurodegenerative diseases with overlapping clinical phenotypes based on impaired motoneuron function. However, the pathomechanisms of both diseases are largely unknown, and it is still unclear whether they converge on the molecular level. SMA is a monogenic disease caused by low levels of functional Survival of Motoneuron (SMN) protein, whereas ALS involves multiple genes as well as environmental factors. Recent evidence argues for involvement of actin regulation as a causative and dysregulated process in both diseases. ALS-causing mutations in the actin-binding protein profilin-1 as well as the ability of the SMN protein to directly bind to profilins argue in favor of a common molecular mechanism involving the actin cytoskeleton. Profilins are major regulat ors of actin-dynamics being involved in multiple neuronal motility and transport processes as well as modulation of synaptic functions that are impaired in models of both motoneuron diseases. In this article, we review the current literature in SMA and ALS research with a focus on the actin cytoskeleton. We propose a common molecular mechanism that explains the degeneration of motoneurons for SMA and some cases of ALS.
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Affiliation(s)
- Niko Hensel
- 1 Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,2 Niedersachsen Network on Neuroinfectiology (N-RENNT), Hannover, Germany
| | - Peter Claus
- 1 Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,2 Niedersachsen Network on Neuroinfectiology (N-RENNT), Hannover, Germany.,3 Center for Systems Neuroscience (ZSN), Hannover, Germany
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24
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Iizuka Y, Mooneyham A, Sieben A, Chen K, Maile M, Hellweg R, Schütz F, Teckle K, Starr T, Thayanithy V, Vogel RI, Lou E, Lee MK, Bazzaro M. UNC-45A is required for neurite extension via controlling NMII activation. Mol Biol Cell 2017; 28:1337-1346. [PMID: 28356421 PMCID: PMC5426848 DOI: 10.1091/mbc.e16-06-0381] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 03/15/2017] [Accepted: 03/21/2017] [Indexed: 01/13/2023] Open
Abstract
UNC-45A is a novel regulator of neuronal differentiation. UNC-45A localizes at the growth cone, binds to NMIIA and NMIIB, and is disposable for neuronal survival but is required for neurite initiation and extension via regulating NMII activation. Thus UNC-45A is a potential master regulator of a number of NMII-mediated cellular processes. UNC-45A is a highly conserved member of the UNC-45/CRO1/She4p family of proteins, which act as chaperones for conventional and nonconventional myosins. NMII mediates contractility and actin-based motility, which are fundamental for proper growth cone motility and neurite extension. The presence and role of UNC-45A in neuronal differentiation have been largely unknown. Here we demonstrate that UNC-45A is a novel growth cone–localized, NMII-associated component of the multiprotein complex regulating growth cone dynamics. We show that UNC-45A is dispensable for neuron survival but required for neurite elongation. Mechanistically, loss of UNC-45A results in increased levels of NMII activation. Collectively our results provide novel insights into the molecular mechanisms of neurite growth and define UNC-45A as a novel and master regulator of NMII-mediated cellular processes in neurons.
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Affiliation(s)
- Yoshie Iizuka
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Ashley Mooneyham
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Andrew Sieben
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Kevin Chen
- Department of Biology, University of Maryland, Baltimore, MD 21250
| | - Makayla Maile
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Raffaele Hellweg
- Breast Unit, University of Heidelberg, 69120 Heidelberg, Germany
| | - Florian Schütz
- Breast Unit, University of Heidelberg, 69120 Heidelberg, Germany
| | - Kebebush Teckle
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Timothy Starr
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Venugopal Thayanithy
- Division of Hematology, Oncology and Transplantation, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Rachel Isaksson Vogel
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Emil Lou
- Division of Hematology, Oncology and Transplantation, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Michael K Lee
- Department of Neuroscience, University of Minnesota Twin Cities, Minneapolis, MN 55455
| | - Martina Bazzaro
- Masonic Cancer Center and Department of Obstetrics, Gynecology and Women's Heath, University of Minnesota Twin Cities, Minneapolis, MN 55455
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25
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Seno T, Ikeno T, Mennya K, Kurishita M, Sakae N, Sato M, Takada H, Konishi Y. Kinesin-1 sorting in axons controls the differential retraction of arbor terminals. J Cell Sci 2016; 129:3499-510. [PMID: 27505885 DOI: 10.1242/jcs.183806] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 08/02/2016] [Indexed: 01/13/2023] Open
Abstract
The ability of neurons to generate multiple arbor terminals from a single axon is crucial for establishing proper neuronal wiring. Although growth and retraction of arbor terminals are differentially regulated within the axon, the mechanisms by which neurons locally control their structure remain largely unknown. In the present study, we found that the kinesin-1 (Kif5 proteins) head domain (K5H) preferentially marks a subset of arbor terminals. Time-lapse imaging clarified that these arbor terminals were more stable than others, because of a low retraction rate. Local inhibition of kinesin-1 in the arbor terminal by chromophore-assisted light inactivation (CALI) enhanced the retraction rate. The microtubule turnover was locally regulated depending on the length from the branching point to the terminal end, but did not directly correlate with the presence of K5H. By contrast, F-actin signal values in arbor terminals correlated spatiotemporally with K5H, and inhibition of actin turnover prevented retraction. Results from the present study reveal a new system mediated by kinesin-1 sorting in axons that differentially controls stability of arbor terminals.
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Affiliation(s)
- Takeshi Seno
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Tatsuki Ikeno
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Kousuke Mennya
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Masayuki Kurishita
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Narumi Sakae
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Makoto Sato
- Life Science Innovation Center, University of Fukui, Fukui 910-8507, Japan Research Center for Child Mental Development, University of Fukui, Fukui 910-1193, Japan Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan United Graduate School of Child Development, Osaka University, Kanazawa University-Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka University, Osaka 565-0871, Japan
| | - Hiroki Takada
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Yoshiyuki Konishi
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan Life Science Innovation Center, University of Fukui, Fukui 910-8507, Japan Department of Materials Science and Biotechnology, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
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26
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Pacheco A, Gallo G. Actin filament-microtubule interactions in axon initiation and branching. Brain Res Bull 2016; 126:300-310. [PMID: 27491623 DOI: 10.1016/j.brainresbull.2016.07.013] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 07/28/2016] [Accepted: 07/30/2016] [Indexed: 10/21/2022]
Abstract
Neurons begin life as spherical cells. A major hallmark of neuronal development is the formation of elongating processes from the cell body which subsequently differentiate into dendrites and the axon. The formation and later development of neuronal processes is achieved through the concerted organization of actin filaments and microtubules. Here, we review the literature regarding recent advances in the understanding of cytoskeletal interactions in neurons focusing on the initiation of processes from neuronal cell bodies and the collateral branching of axons. The complex crosstalk between cytoskeletal elements is mediated by a cohort of proteins that either bind both cytoskeletal systems or allow one to regulate the other. Recent studies have highlighted the importance of microtubule plus-tip proteins in the regulation of the dynamics and organization of actin filaments, while also providing a mechanism for the subcellular capture and guidance of microtubule tips by actin filaments. Although the understanding of cytoskeletal crosstalk and interactions in neuronal morphogenesis has advanced significantly in recent years the appreciation of the neuron as an integrated cytoskeletal system remains a frontier.
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Affiliation(s)
- Almudena Pacheco
- Temple University, Lewis Kats School of Medicine, Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, 3500 North Broad Street, Philadelphia, PA 19140, United States
| | - Gianluca Gallo
- Temple University, Lewis Kats School of Medicine, Shriners Hospitals Pediatric Research Center, Department of Anatomy and Cell Biology, 3500 North Broad Street, Philadelphia, PA 19140, United States.
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27
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Delivery of HIV-1 Nef Protein in Mammalian Cells Using Cell Penetrating Peptides as a Candidate Therapeutic Vaccine. Int J Pept Res Ther 2016. [DOI: 10.1007/s10989-016-9547-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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28
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Myers KA, He Y, Hasaka TP, Baas PW. Microtubule Transport in the Axon: Re-thinking a Potential Role for the Actin Cytoskeleton. Neuroscientist 2016; 12:107-18. [PMID: 16514008 DOI: 10.1177/1073858405283428] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Microtubules are transported down the axon as short pieces by molecular motor proteins. One popular idea is that these microtubules are transported by forces generated against the actin cytoskeleton. The motor for such transport is thought to be cytoplasmic dynein. Here, the authors review this model and discuss recent studies that sought to test it. These studies suggest that the model is valid but incomplete. Microtubule transport is bidirectional and can utilize either actin filaments or longer microtubules as a substrate in the anterograde direction but only longer microtubules in the retrograde direction. Cytoplasmic dynein is one participating motor but not the only one. The authors speculate that the category of anterograde microtubule transport that involves actin filaments may have specialized functions. The relevant forces that transport short microtubules may also be crucial for the manner by which the longer immobile microtubules interact with actin filaments during events such as axonal retraction and growth cone turning.
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Affiliation(s)
- Kenneth A Myers
- Department of Neurobiology and Anatomy, Drexel University College of Medicine, Philadelphia, PA 19129, USA
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29
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Mardani G, Bolhassani A, Agi E, Shahbazi S, Mehdi Sadat S. Protein vaccination with HPV16 E7/Pep-1 nanoparticles elicits a protective T-helper cell-mediated immune response. IUBMB Life 2016; 68:459-67. [DOI: 10.1002/iub.1503] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 03/25/2016] [Accepted: 03/30/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Golnaz Mardani
- Department of Hepatitis and AIDS; Pasteur Institute of Iran; Tehran Iran
- Department of Biotechnology, Faculty of Advanced Sciences and Technology, Pharmaceutical Sciences Branch; Islamic Azad University; Tehran Iran
| | - Azam Bolhassani
- Department of Hepatitis and AIDS; Pasteur Institute of Iran; Tehran Iran
| | - Elnaz Agi
- Department of Hepatitis and AIDS; Pasteur Institute of Iran; Tehran Iran
| | - Sepideh Shahbazi
- Department of Hepatitis and AIDS; Pasteur Institute of Iran; Tehran Iran
| | - Seyed Mehdi Sadat
- Department of Hepatitis and AIDS; Pasteur Institute of Iran; Tehran Iran
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30
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Menon S, Gupton SL. Building Blocks of Functioning Brain: Cytoskeletal Dynamics in Neuronal Development. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2016; 322:183-245. [PMID: 26940519 PMCID: PMC4809367 DOI: 10.1016/bs.ircmb.2015.10.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Neural connectivity requires proper polarization of neurons, guidance to appropriate target locations, and establishment of synaptic connections. From when neurons are born to when they finally reach their synaptic partners, neurons undergo constant rearrangment of the cytoskeleton to achieve appropriate shape and polarity. Of particular importance to neuronal guidance to target locations is the growth cone at the tip of the axon. Growth-cone steering is also dictated by the underlying cytoskeleton. All these changes require spatiotemporal control of the cytoskeletal machinery. This review summarizes the proteins that are involved in modulating the actin and microtubule cytoskeleton during the various stages of neuronal development.
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Affiliation(s)
- Shalini Menon
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America
| | - Stephanie L Gupton
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC, United States of America; Neuroscience Center and Curriculum in Neurobiology, University of North Carolina, Chapel Hill, NC, United States of America; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC, United States of America.
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31
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Chetta J, Love JM, Bober BG, Shah SB. Bidirectional actin transport is influenced by microtubule and actin stability. Cell Mol Life Sci 2015; 72:4205-20. [PMID: 26043972 PMCID: PMC11113749 DOI: 10.1007/s00018-015-1933-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 05/14/2015] [Accepted: 05/19/2015] [Indexed: 12/16/2022]
Abstract
Local and long-distance transport of cytoskeletal proteins is vital to neuronal maintenance and growth. Though recent progress has provided insight into the movement of microtubules and neurofilaments, mechanisms underlying the movement of actin remain elusive, in large part due to rapid transitions between its filament states and its diverse cellular localization and function. In this work, we integrated live imaging of rat sensory neurons, image processing, multiple regression analysis, and mathematical modeling to perform the first quantitative, high-resolution investigation of GFP-actin identity and movement in individual axons. Our data revealed that filamentous actin densities arise along the length of the axon and move short but significant distances bidirectionally, with a net anterograde bias. We directly tested the role of actin and microtubules in this movement. We also confirmed a role for actin densities in extension of axonal filopodia, and demonstrated intermittent correlation of actin and mitochondrial movement. Our results support a novel mechanism underlying slow component axonal transport, in which the stability of both microtubule and actin cytoskeletal components influence the mobility of filamentous actin.
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Affiliation(s)
- Joshua Chetta
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
| | - James M Love
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA
| | - Brian G Bober
- Department of Bioengineering, University of California, San Diego, La Jolla, CA, USA
| | - Sameer B Shah
- Fischell Department of Bioengineering, University of Maryland, College Park, MD, USA.
- Departments of Orthopaedic Surgery and Bioengineering, University of California, San Diego, 9500 Gilman Drive, MC 0863, La Jolla, CA, 92093, USA.
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32
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Abstract
Maintenance of neuronal polarity and regulation of cytoskeletal dynamics are vital during development and to uphold synaptic activity in neuronal networks. Here we show that soluble β-amyloid (Aβ) disrupts actin and microtubule (MT) dynamics via activation of RhoA and inhibition of histone deacetylase 6 (HDAC6) in cultured hippocampal neurons. The contact of Aβ with the extracellular membrane promotes RhoA activation, leading to growth cone collapse and neurite retraction, which might be responsible for hampered neuronal pathfinding and migration in Alzheimer's disease (AD). The inhibition of HDAC6 by Aβ increases the level of heterodimeric acetylated tubulin and acetylated tau, both of which have been found altered in AD. We also find that the loss of HDAC6 activity perturbs the integrity of axon initial segment (AIS), resulting in mislocalization of ankyrin G and increased MT instability in the AIS concomitant with loss of polarized localization of tau and impairment of action potential firing.
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33
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Speranza L, Giuliano T, Volpicelli F, De Stefano ME, Lombardi L, Chambery A, Lacivita E, Leopoldo M, Bellenchi GC, di Porzio U, Crispino M, Perrone-Capano C. Activation of 5-HT7 receptor stimulates neurite elongation through mTOR, Cdc42 and actin filaments dynamics. Front Behav Neurosci 2015; 9:62. [PMID: 25814944 PMCID: PMC4356071 DOI: 10.3389/fnbeh.2015.00062] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 02/23/2015] [Indexed: 12/02/2022] Open
Abstract
Recent studies have indicated that the serotonin receptor subtype 7 (5-HT7R) plays a crucial role in shaping neuronal morphology during embryonic and early postnatal life. Here we show that pharmacological stimulation of 5-HT7R using a highly selective agonist, LP-211, enhances neurite outgrowth in neuronal primary cultures from the cortex, hippocampus and striatal complex of embryonic mouse brain, through multiple signal transduction pathways. All these signaling systems, involving mTOR, the Rho GTPase Cdc42, Cdk5, and ERK, are known to converge on the reorganization of cytoskeletal proteins that subserve neurite outgrowth. Indeed, our data indicate that neurite elongation stimulated by 5-HT7R is modulated by drugs affecting actin polymerization. In addition, we show, by 2D Western blot analyses, that treatment of neuronal cultures with LP-211 alters the expression profile of cofilin, an actin binding protein involved in microfilaments dynamics. Furthermore, by using microfluidic chambers that physically separate axons from the soma and dendrites, we demonstrate that agonist-dependent activation of 5-HT7R stimulates axonal elongation. Our results identify for the first time several signal transduction pathways, activated by stimulation of 5-HT7R, that converge to promote cytoskeleton reorganization and consequent modulation of axonal elongation. Therefore, the activation of 5-HT7R might represent one of the key elements regulating CNS connectivity and plasticity during development.
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Affiliation(s)
- Luisa Speranza
- Department of Biology, University of Naples Federico II Naples, Italy ; Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR Naples, Italy
| | - Teresa Giuliano
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR Naples, Italy
| | - Floriana Volpicelli
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR Naples, Italy ; Department of Pharmacy, University of Naples Federico II Naples, Italy
| | - M Egle De Stefano
- Department of Biology and Biotechnology "Charles Darwin", Istituto Pasteur Fondazione Cenci Bolognetti, University of Rome La Sapienza Rome, Italy
| | - Loredana Lombardi
- Department of Biology and Biotechnology "Charles Darwin", Istituto Pasteur Fondazione Cenci Bolognetti, University of Rome La Sapienza Rome, Italy
| | - Angela Chambery
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Second University of Naples Naples, Italy ; IRCCS, Multimedica Milano, Italy
| | - Enza Lacivita
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari Bari, Italy
| | - Marcello Leopoldo
- Department of Pharmacy - Pharmaceutical Sciences, University of Bari Bari, Italy
| | - Gian C Bellenchi
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR Naples, Italy
| | - Umberto di Porzio
- Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR Naples, Italy
| | - Marianna Crispino
- Department of Biology, University of Naples Federico II Naples, Italy
| | - Carla Perrone-Capano
- Department of Biology, University of Naples Federico II Naples, Italy ; Institute of Genetics and Biophysics "Adriano Buzzati Traverso", CNR Naples, Italy
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Variable combinations of specific ephrin ligand/Eph receptor pairs control embryonic tissue separation. PLoS Biol 2014; 12:e1001955. [PMID: 25247423 PMCID: PMC4172438 DOI: 10.1371/journal.pbio.1001955] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Accepted: 08/15/2014] [Indexed: 11/22/2022] Open
Abstract
Vertebrate embryonic cells recognize self from non-self, thus restricting repulsion at tissue boundaries, through a combination of multiple ephrins and Eph receptors, simply based on binding selectivity and asymmetric expression. Ephrins and Eph receptors are involved in the establishment of vertebrate tissue boundaries. The complexity of the system is puzzling, however in many instances, tissues express multiple ephrins and Ephs on both sides of the boundary, a situation that should in principle cause repulsion between cells within each tissue. Although co-expression of ephrins and Eph receptors is widespread in embryonic tissues, neurons, and cancer cells, it is still unresolved how the respective signals are integrated into a coherent output. We present a simple explanation for the confinement of repulsion to the tissue interface: Using the dorsal ectoderm–mesoderm boundary of the Xenopus embryo as a model, we identify selective functional interactions between ephrin–Eph pairs that are expressed in partial complementary patterns. The combined repulsive signals add up to be strongest across the boundary, where they reach sufficient intensity to trigger cell detachments. The process can be largely explained using a simple model based exclusively on relative ephrin and Eph concentrations and binding affinities. We generalize these findings for the ventral ectoderm–mesoderm boundary and the notochord boundary, both of which appear to function on the same principles. These results provide a paradigm for how developmental systems may integrate multiple cues to generate discrete local outcomes. How embryonic tissues separate from each other to shape the developing organism is a fundamental question in developmental biology. In vertebrates, this process relies on local repulsive reactions specifically generated at contacts between cells of different types. These reactions are triggered by typical repulsive cell surface cues, the ephrin ligands, and Eph receptors. However, the expression of multiple ephrins and the Eph receptors by each cell type represents a puzzle: Why is repulsion observed only at the tissue interface and not within the tissue itself? By studying three cases of separation in the early amphibian embryo, we uncover a surprisingly simple logic underlying this phenomenon, which can be explained by the selectivity of ligand–receptor interactions and by their asymmetric distribution. The system is set such that, despite generalized interactions throughout the tissues, it is only at contacts between different cell types that the overall repulsive output is sufficiently strong to overcome cell–cell adhesion. Our study may serve as paradigm for how systematic dissection of complex cellular systems can reduce them to simple laws and make them intelligible.
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Roland AB, Ricobaraza A, Carrel D, Jordan BM, Rico F, Simon A, Humbert-Claude M, Ferrier J, McFadden MH, Scheuring S, Lenkei Z. Cannabinoid-induced actomyosin contractility shapes neuronal morphology and growth. eLife 2014; 3:e03159. [PMID: 25225054 PMCID: PMC4179426 DOI: 10.7554/elife.03159] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 09/09/2014] [Indexed: 12/23/2022] Open
Abstract
Endocannabinoids are recently recognized regulators of brain development, but molecular effectors downstream of type-1 cannabinoid receptor (CB1R)-activation remain incompletely understood. We report atypical coupling of neuronal CB1Rs, after activation by endo- or exocannabinoids such as the marijuana component ∆(9)-tetrahydrocannabinol, to heterotrimeric G12/G13 proteins that triggers rapid and reversible non-muscle myosin II (NM II) dependent contraction of the actomyosin cytoskeleton, through a Rho-GTPase and Rho-associated kinase (ROCK). This induces rapid neuronal remodeling, such as retraction of neurites and axonal growth cones, elevated neuronal rigidity, and reshaping of somatodendritic morphology. Chronic pharmacological inhibition of NM II prevents cannabinoid-induced reduction of dendritic development in vitro and leads, similarly to blockade of endocannabinoid action, to excessive growth of corticofugal axons into the sub-ventricular zone in vivo. Our results suggest that CB1R can rapidly transform the neuronal cytoskeleton through actomyosin contractility, resulting in cellular remodeling events ultimately able to affect the brain architecture and wiring.
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Affiliation(s)
- Alexandre B Roland
- Brain Plasticity Unit, ESPCI-ParisTech, CNRS UMR8249, Paris, France
- FAS Center for Systems Biology, Harvard University, Cambridge, United States
| | - Ana Ricobaraza
- Brain Plasticity Unit, ESPCI-ParisTech, CNRS UMR8249, Paris, France
| | - Damien Carrel
- Brain Plasticity Unit, ESPCI-ParisTech, CNRS UMR8249, Paris, France
| | - Benjamin M Jordan
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, United States
| | - Felix Rico
- U1006 INSERM, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Anne Simon
- Brain Plasticity Unit, ESPCI-ParisTech, CNRS UMR8249, Paris, France
| | | | - Jeremy Ferrier
- Brain Plasticity Unit, ESPCI-ParisTech, CNRS UMR8249, Paris, France
| | | | - Simon Scheuring
- U1006 INSERM, Aix-Marseille Université, Parc Scientifique et Technologique de Luminy, Marseille, France
| | - Zsolt Lenkei
- Brain Plasticity Unit, ESPCI-ParisTech, CNRS UMR8249, Paris, France
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36
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Lamprecht R. The actin cytoskeleton in memory formation. Prog Neurobiol 2014; 117:1-19. [DOI: 10.1016/j.pneurobio.2014.02.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 02/02/2014] [Accepted: 02/03/2014] [Indexed: 01/21/2023]
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37
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Non-muscle myosin II regulates neuronal actin dynamics by interacting with guanine nucleotide exchange factors. PLoS One 2014; 9:e95212. [PMID: 24752242 PMCID: PMC3994028 DOI: 10.1371/journal.pone.0095212] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 03/25/2014] [Indexed: 11/24/2022] Open
Abstract
Background Non-muscle myosin II (NM II) regulates a wide range of cellular functions, including neuronal differentiation, which requires precise spatio-temporal activation of Rho GTPases. The molecular mechanism underlying the NM II-mediated activation of Rho GTPases is poorly understood. The present study explored the possibility that NM II regulates neuronal differentiation, particularly morphological changes in growth cones and the distal axon, through guanine nucleotide exchange factors (GEFs) of the Dbl family. Principal Findings NM II colocalized with GEFs, such as βPIX, kalirin and intersectin, in growth cones. Inactivation of NM II by blebbistatin (BBS) led to the increased formation of short and thick filopodial actin structures at the periphery of growth cones. In line with these observations, FRET analysis revealed enhanced Cdc42 activity in BBS-treated growth cones. BBS treatment also induced aberrant targeting of various GEFs to the distal axon where GEFs were seldom observed under physiological conditions. As a result, numerous protrusions and branches were generated on the shaft of the distal axon. The disruption of the NM II–GEF interactions by overexpression of the DH domains of βPIX or Tiam1, or by βPIX depletion with specific siRNAs inhibited growth cone formation and induced slender axons concomitant with multiple branches in cultured hippocampal neurons. Finally, stimulation with nerve growth factor induced transient dissociation of the NM II–GEF complex, which was closely correlated with the kinetics of Cdc42 and Rac1 activation. Conclusion Our results suggest that NM II maintains proper morphology of neuronal growth cones and the distal axon by regulating actin dynamics through the GEF–Rho GTPase signaling pathway.
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38
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Prokosch V, Chiwitt C, Rose K, Thanos S. Deciphering proteins and their functions in the regenerating retina. Expert Rev Proteomics 2014; 7:775-95. [DOI: 10.1586/epr.10.47] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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39
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Al-Ali H, Schürer SC, Lemmon VP, Bixby JL. Chemical interrogation of the neuronal kinome using a primary cell-based screening assay. ACS Chem Biol 2013; 8:1027-36. [PMID: 23480631 DOI: 10.1021/cb300584e] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A fundamental impediment to functional recovery from spinal cord injury (SCI) and traumatic brain injury is the lack of sufficient axonal regeneration in the adult central nervous system. There is thus a need to develop agents that can stimulate axon growth to re-establish severed connections. Given the critical role played by protein kinases in regulating axon growth and the potential for pharmacological intervention, small molecule protein kinase inhibitors present a promising therapeutic strategy. Here, we report a robust cell-based phenotypic assay, utilizing primary rat hippocampal neurons, for identifying small molecule kinase inhibitors that promote neurite growth. The assay is highly reliable and suitable for medium-throughput screening, as indicated by its Z'-factor of 0.73. A focused structurally diverse library of protein kinase inhibitors was screened, revealing several compound groups with the ability to strongly and consistently promote neurite growth. The best performing bioassay hit robustly and consistently promoted axon growth in a postnatal cortical slice culture assay. This study can serve as a jumping-off point for structure activity relationship (SAR) and other drug discovery approaches toward the development of drugs for treating SCI and related neurological pathologies.
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Affiliation(s)
- Hassan Al-Ali
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Stephan C. Schürer
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - Vance P. Lemmon
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
| | - John L. Bixby
- Miami Project to Cure Paralysis, ‡Center for Computational Sciences, and Departments of §Neurological Surgery and ∥Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, United States
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40
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Zhang XF, Hyland C, Van Goor D, Forscher P. Calcineurin-dependent cofilin activation and increased retrograde actin flow drive 5-HT-dependent neurite outgrowth in Aplysia bag cell neurons. Mol Biol Cell 2012; 23:4833-48. [PMID: 23097492 PMCID: PMC3521690 DOI: 10.1091/mbc.e12-10-0715] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Neurite outgrowth in response to soluble growth factors often involves changes in intracellular Ca(2+); however, mechanistic roles for Ca(2+) in controlling the underlying dynamic cytoskeletal processes have remained enigmatic. Bag cell neurons exposed to serotonin (5-hydroxytryptamine [5-HT]) respond with a threefold increase in neurite outgrowth rates. Outgrowth depends on phospholipase C (PLC) → inositol trisphosphate → Ca(2+) → calcineurin signaling and is accompanied by increased rates of retrograde actin network flow in the growth cone P domain. Calcineurin inhibitors had no effect on Ca(2+) release or basal levels of retrograde actin flow; however, they completely suppressed 5-HT-dependent outgrowth and F-actin flow acceleration. 5-HT treatments were accompanied by calcineurin-dependent increases in cofilin activity in the growth cone P domain. 5-HT effects were mimicked by direct activation of PLC, suggesting that increased actin network treadmilling may be a widespread mechanism for promoting neurite outgrowth in response to neurotrophic factors.
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Affiliation(s)
- Xiao-Feng Zhang
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA
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41
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Nievergall E, Lackmann M, Janes PW. Eph-dependent cell-cell adhesion and segregation in development and cancer. Cell Mol Life Sci 2012; 69:1813-42. [PMID: 22204021 PMCID: PMC11114713 DOI: 10.1007/s00018-011-0900-6] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Revised: 11/06/2011] [Accepted: 11/28/2011] [Indexed: 01/23/2023]
Abstract
Numerous studies attest to essential roles for Eph receptors and their ephrin ligands in controlling cell positioning and tissue patterning during normal and oncogenic development. These studies suggest multiple, sometimes contradictory, functions of Eph-ephrin signalling, which under different conditions can promote either spreading and cell-cell adhesion or cytoskeletal collapse, cell rounding, de-adhesion and cell-cell segregation. A principle determinant of the balance between these two opposing responses is the degree of receptor/ligand clustering and activation. This equilibrium is likely altered in cancers and modulated by somatic mutations of key Eph family members that have emerged as candidate cancer markers in recent profiling studies. In addition, cross-talk amongst Ephs and with other signalling pathways significantly modulates cell-cell adhesion, both between and within Eph- and ephrin-expressing cell populations. This review summarises our current understanding of how Eph receptors control cell adhesion and morphology, and presents examples demonstrating the importance of these events in normal development and cancer.
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Affiliation(s)
- Eva Nievergall
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800 Australia
- Present Address: Haematology Department, SA Pathology, Frome Road, Adelaide, SA 5000 Australia
| | - Martin Lackmann
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800 Australia
| | - Peter W. Janes
- Department of Biochemistry and Molecular Biology, Monash University, Wellington Road, Clayton, VIC 3800 Australia
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42
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Marsick BM, Roche FK, Letourneau PC. Repulsive axon guidance cues ephrin-A2 and slit3 stop protrusion of the growth cone leading margin concurrently with inhibition of ADF/cofilin and ERM proteins. Cytoskeleton (Hoboken) 2012; 69:496-505. [PMID: 22328420 DOI: 10.1002/cm.21016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Accepted: 02/01/2012] [Indexed: 11/08/2022]
Abstract
Axonal growth cones turn away from repulsive guidance cues. This may start with reduced protrusive motility in the region the growth cone leading margin that is closer to the source of repulsive cue. Using explants of E7 chick temporal retina, we examine the effects of two repulsive guidance cues, ephrin-A2 and slit3, on retinal ganglion cell growth cone protrusive activity, total F-actin, free F-actin barbed ends, and the activities (phosphorylation states) of actin regulatory proteins, ADF/cofilin and ezrin, radixin, moesin (ERM) proteins. Ephrin-A2 rapidly stops protrusive activity simultaneously with reducing F-actin, free barbed ends and the activities of ADF/cofilin and ERM proteins. Slit3 also stops protrusion and reduces the activities of ADF/cofilin and ERM proteins. We interpret these results as indicating that repulsive guidance cues inhibit actin polymerization and actin-membrane linkage to stop protrusive activity. Retrograde F-actin flow withdraws actin to the C-domain, where F-actin bundles interact with myosin II to generate contractile forces that can collapse and retract the growth cone. Our results suggest that common mechanisms are used by repulsive guidance cue to disable growth cone motility and remodel growing axon terminals.
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Affiliation(s)
- Bonnie M Marsick
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota 55455, USA
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43
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Van Goor D, Hyland C, Schaefer AW, Forscher P. The role of actin turnover in retrograde actin network flow in neuronal growth cones. PLoS One 2012; 7:e30959. [PMID: 22359556 PMCID: PMC3281045 DOI: 10.1371/journal.pone.0030959] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Accepted: 12/28/2011] [Indexed: 11/18/2022] Open
Abstract
The balance of actin filament polymerization and depolymerization maintains a steady state network treadmill in neuronal growth cones essential for motility and guidance. Here we have investigated the connection between depolymerization and treadmilling dynamics. We show that polymerization-competent barbed ends are concentrated at the leading edge and depolymerization is distributed throughout the peripheral domain. We found a high-to-low G-actin gradient between peripheral and central domains. Inhibiting turnover with jasplakinolide collapsed this gradient and lowered leading edge barbed end density. Ultrastructural analysis showed dramatic reduction of leading edge actin filament density and filament accumulation in central regions. Live cell imaging revealed that the leading edge retracted even as retrograde actin flow rate decreased exponentially. Inhibition of myosin II activity before jasplakinolide treatment lowered baseline retrograde flow rates and prevented leading edge retraction. Myosin II activity preferentially affected filopodial bundle disassembly distinct from the global effects of jasplakinolide on network turnover. We propose that growth cone retraction following turnover inhibition resulted from the persistence of myosin II contractility even as leading edge assembly rates decreased. The buildup of actin filaments in central regions combined with monomer depletion and reduced polymerization from barbed ends suggests a mechanism for the observed exponential decay in actin retrograde flow. Our results show that growth cone motility is critically dependent on continuous disassembly of the peripheral actin network.
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Affiliation(s)
- David Van Goor
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Callen Hyland
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Andrew W. Schaefer
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
| | - Paul Forscher
- Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut, United States of America
- * E-mail:
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44
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Abstract
HGAL, a prognostic biomarker in patients with diffuse large B-cell lymphoma and classic Hodgkin lymphoma, inhibits lymphocyte and lymphoma cell motility by activating the RhoA signaling cascade and interacting with actin and myosin proteins. Although HGAL expression is limited to germinal center (GC) lymphocytes and GC-derived lymphomas, little is known about its regulation. miR-155 is implicated in control of GC reaction and lymphomagenesis. We demonstrate that miR-155 directly down-regulates HGAL expression by binding to its 3'-untranslated region, leading to decreased RhoA activation and increased spontaneous and chemoattractant-induced lymphoma cell motility. The effects of miR-155 on RhoA activation and cell motility can be rescued by transfection of HGAL lacking the miR-155 binding site. This inhibitory effect of miR-155 suggests that it may have a key role in the loss of HGAL expression on differentiation of human GC B cells to plasma cell. Furthermore, this effect may contribute to lymphoma cell dissemination and aggressiveness, characteristic of activated B cell-like diffuse large B-cell lymphoma typically expressing high levels of miR-155 and lacking HGAL expression.
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45
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Lamprecht R. The roles of the actin cytoskeleton in fear memory formation. Front Behav Neurosci 2011; 5:39. [PMID: 21808614 PMCID: PMC3139223 DOI: 10.3389/fnbeh.2011.00039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2011] [Accepted: 07/02/2011] [Indexed: 01/08/2023] Open
Abstract
The formation and storage of fear memory is needed to adapt behavior and avoid danger during subsequent fearful events. However, fear memory may also play a significant role in stress and anxiety disorders. When fear becomes disproportionate to that necessary to cope with a given stimulus, or begins to occur in inappropriate situations, a fear or anxiety disorder exists. Thus, the study of cellular and molecular mechanisms underpinning fear memory may shed light on the formation of memory and on anxiety and stress related disorders. Evidence indicates that fear learning leads to changes in neuronal synaptic transmission and morphology in brain areas underlying fear memory formation including the amygdala and hippocampus. The actin cytoskeleton has been shown to participate in these key neuronal processes. Recent findings show that the actin cytoskeleton is needed for fear memory formation and extinction. Moreover, the actin cytoskeleton is involved in synaptic plasticity and in neuronal morphogenesis in brain areas that mediate fear memory. The actin cytoskeleton may therefore mediate between synaptic transmission during fear learning and long-term cellular alterations mandatory for fear memory formation.
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Affiliation(s)
- Raphael Lamprecht
- Faculty of Natural Sciences, Department of Neurobiology and Ethology, University of Haifa Haifa, Israel
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Moreno-López B, Sunico CR, González-Forero D. NO orchestrates the loss of synaptic boutons from adult "sick" motoneurons: modeling a molecular mechanism. Mol Neurobiol 2010; 43:41-66. [PMID: 21190141 DOI: 10.1007/s12035-010-8159-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2010] [Accepted: 12/02/2010] [Indexed: 12/14/2022]
Abstract
Synapse elimination is the main factor responsible for the cognitive decline accompanying many of the neuropathological conditions affecting humans. Synaptic stripping of motoneurons is also a common hallmark of several motor pathologies. Therefore, knowledge of the molecular basis underlying this plastic process is of central interest for the development of new therapeutic tools. Recent advances from our group highlight the role of nitric oxide (NO) as a key molecule triggering synapse loss in two models of motor pathologies. De novo expression of the neuronal isoform of NO synthase (nNOS) in motoneurons commonly occurs in response to the physical injury of a motor nerve and in the course of amyotrophic lateral sclerosis. In both conditions, this event precedes synaptic withdrawal from motoneurons. Strikingly, nNOS-synthesized NO is "necessary" and "sufficient" to induce synaptic detachment from motoneurons. The mechanism involves a paracrine/retrograde action of NO on pre-synaptic structures, initiating a downstream signaling cascade that includes sequential activation of (1) soluble guanylyl cyclase, (2) cyclic guanosine monophosphate-dependent protein kinase, and (3) RhoA/Rho kinase (ROCK) signaling. Finally, ROCK activation promotes phosphorylation of regulatory myosin light chain, which leads to myosin activation and actomyosin contraction. This latter event presumably contributes to the contractile force to produce ending axon retraction. Several findings support that this mechanism may operate in the most prevalent neurodegenerative diseases.
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Affiliation(s)
- Bernardo Moreno-López
- Grupo de NeuroDegeneración y NeuroReparación (GRUNEDERE), Área de Fisiología, Facultad de Medicina, Universidad de Cádiz, Plaza Falla, 9, 11003 Cádiz, Spain.
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Petros TJ, Bryson JB, Mason C. Ephrin-B2 elicits differential growth cone collapse and axon retraction in retinal ganglion cells from distinct retinal regions. Dev Neurobiol 2010; 70:781-94. [PMID: 20629048 DOI: 10.1002/dneu.20821] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The circuit for binocular vision and stereopsis is established at the optic chiasm, where retinal ganglion cell (RGC) axons diverge into the ipsilateral and contralateral optic tracts. In the mouse retina, ventrotemporal (VT) RGCs express the guidance receptor EphB1, which interacts with the repulsive guidance cue ephrin-B2 on radial glia at the optic chiasm to direct VT RGC axons ipsilaterally. RGCs in the ventral retina also express EphB2, which interacts with ephrin-B2, whereas dorsal RGCs express low levels of EphB receptors. To investigate how growth cones of RGCs from different retinal regions respond upon initial contact with ephrin-B2, we utilized time-lapse imaging to characterize the effects of ephrin-B2 on growth cone collapse and axon retraction in real time. We demonstrate that bath application of ephrin-B2 induces rapid and sustained growth cone collapse and axon retraction in VT RGC axons, whereas contralaterally-projecting dorsotemporal RGCs display moderate growth cone collapse and little axon retraction. Dose response curves reveal that contralaterally-projecting ventronasal axons are less sensitive to ephrin-B2 treatment compared to VT axons. Additionally, we uncovered a specific role for Rho kinase signaling in the retraction of VT RGC axons but not in growth cone collapse. The detailed characterization of growth cone behavior in this study comprises an assay for the study of Eph signaling in RGCs, and provides insight into the phenomena of growth cone collapse and axon retraction in general.
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Affiliation(s)
- Timothy J Petros
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, New York 10032, USA
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Chetta J, Kye C, Shah SB. Cytoskeletal dynamics in response to tensile loading of mammalian axons. Cytoskeleton (Hoboken) 2010; 67:650-65. [DOI: 10.1002/cm.20478] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Leading tip drives soma translocation via forward F-actin flow during neuronal migration. J Neurosci 2010; 30:10885-98. [PMID: 20702717 DOI: 10.1523/jneurosci.0240-10.2010] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Neuronal migration involves coordinated extension of the leading process and translocation of the soma, but the relative contribution of different subcellular regions, including the leading process and cell rear, in driving soma translocation remains unclear. By local manipulation of cytoskeletal components in restricted regions of cultured neurons, we examined the molecular machinery underlying the generation of traction force for soma translocation during neuronal migration. In actively migrating cerebellar granule cells in culture, a growth cone (GC)-like structure at the leading tip exhibits high dynamics, and severing the tip or disrupting its dynamics suppressed soma translocation within minutes. Soma translocation was also suppressed by local disruption of F-actin along the leading process but not at the soma, whereas disrupting microtubules along the leading process or at the soma accelerated soma translocation. Fluorescent speckle microscopy using GFP-alpha-actinin showed that a forward F-actin flow along the leading process correlated with and was required for soma translocation, and such F-actin flow depended on myosin II activity. In migrating neurons, myosin II activity was high at the leading tip but low at the soma, and increasing or decreasing this front-to-rear difference accelerated or impeded soma advance. Thus, the tip of the leading process actively pulls the soma forward during neuronal migration through a myosin II-dependent forward F-actin flow along the leading process.
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Norman LL, Aranda-Espinoza H. Cortical Neuron Outgrowth is Insensitive to Substrate Stiffness. Cell Mol Bioeng 2010. [DOI: 10.1007/s12195-010-0137-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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