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Liu W, Gao T, Li N, Shao S, Liu B. Vesicle fusion and release in neurons under dynamic mechanical equilibrium. iScience 2024; 27:109793. [PMID: 38736547 PMCID: PMC11088343 DOI: 10.1016/j.isci.2024.109793] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024] Open
Abstract
Vesicular fusion plays a pivotal role in cellular processes, involving stages like vesicle trafficking, fusion pore formation, content release, and membrane integration or separation. This dynamic process is regulated by a complex interplay of protein assemblies, osmotic forces, and membrane tension, which together maintain a mechanical equilibrium within the cell. Changes in cellular mechanics or external pressures prompt adjustments in this equilibrium, highlighting the system's adaptability. This review delves into the synergy between intracellular proteins, structural components, and external forces in facilitating vesicular fusion and release. It also explores how cells respond to mechanical stress, maintaining equilibrium and offering insights into vesicle fusion mechanisms and the development of neurological disorders.
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Affiliation(s)
- Wenhao Liu
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
| | - Tianyu Gao
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
| | - Na Li
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
- Faculty of Medicine, Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Shuai Shao
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
- Faculty of Medicine, Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
| | - Bo Liu
- Cancer Hospital of Dalian University of Technology, Shenyang 110042, China
- Faculty of Medicine, Liaoning Key Lab of Integrated Circuit and Biomedical Electronic System, Dalian University of Technology, Dalian 116024, China
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Falconieri A, Folino P, Da Palmata L, Raffa V. Nano-pulling stimulates axon regeneration in dorsal root ganglia by inducing stabilization of axonal microtubules and activation of local translation. Front Mol Neurosci 2024; 17:1340958. [PMID: 38633213 PMCID: PMC11022966 DOI: 10.3389/fnmol.2024.1340958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Accepted: 03/11/2024] [Indexed: 04/19/2024] Open
Abstract
Introduction Axonal plasticity is strongly related to neuronal development as well as regeneration. It was recently demonstrated that active mechanical tension, intended as an extrinsic factor, is a valid contribution to the modulation of axonal plasticity. Methods In previous publications, our team validated a the "nano-pulling" method used to apply mechanical forces to developing axons of isolated primary neurons using magnetic nanoparticles (MNP) actuated by static magnetic fields. This method was found to promote axon growth and synaptic maturation. Here, we explore the use of nano-pulling as an extrinsic factor to promote axon regeneration in a neuronal tissue explant. Results Whole dorsal root ganglia (DRG) were thus dissected from a mouse spinal cord, incubated with MNPs, and then stretched. We found that particles were able to penetrate the ganglion and thus become localised both in the somas and in sprouting axons. Our results highlight that nano-pulling doubles the regeneration rate, and this is accompanied by an increase in the arborizing capacity of axons, an accumulation of cellular organelles related to mass addition (endoplasmic reticulum and mitochondria) and pre-synaptic proteins with respect to spontaneous regeneration. In line with the previous results on isolated hippocampal neurons, we observed that this process is coupled to an increase in the density of stable microtubules and activation of local translation. Discussion Our data demonstrate that nano-pulling enhances axon regeneration in whole spinal ganglia exposed to MNPs and external magnetic fields. These preliminary data represent an encouraging starting point for proposing nano-pulling as a biophysical tool for the design of novel therapies based on the use of force as an extrinsic factor for promoting nerve regeneration.
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Wang X, Wang S, Holland MA. Axonal tension contributes to consistent fold placement. SOFT MATTER 2024; 20:3053-3065. [PMID: 38506323 DOI: 10.1039/d4sm00129j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Cortical folding is a critical process during brain development, resulting in morphologies that are both consistent and distinct between individuals and species. While earlier studies have highlighted important aspects of cortical folding, most existing computational models, based on the differential growth theory, fall short of explaining why folds tend to appear in particular locations. The axon tension hypothesis may provide insight into this conundrum; however, there has been significant controversy about a potential role of axonal tension during the gyrification. The common opinion in the field is that axonal tension is inadequate to drive gyrification, but we currently run the risk of discarding this hypothesis without comprehensively studying the role of axonal tension. Here we propose a novel bi-layered finite element model incorporating the two theories, including characteristic axonal tension in the subcortex and differential cortical growth. We show that axon tension can serve as a perturbation sufficient to trigger buckling in simulations; similarly to other types of perturbations, the natural stability behavior of the system tends to determine some characteristics of the folding morphology (e.g. the wavelength) while the perturbation determines the location of folds. Certain geometries, however, can interact or compete with the natural stability of the system to change the wavelength. When multiple perturbations are present, they similarly compete with each other. We found that an axon bundle of reasonable size will overpower up to a 5% thickness perturbation (typical in the literature) and determine fold placement. Finally, when multiple axon tracts are present, even a slight difference in axon stiffness, representing the heterogeneity of axonal connections, is enough to significantly change the folding pattern. While the simulations presented here are a very simple representation of white matter connectivity, our findings point to urgent future research on the role of axon connectivity in cortical folding.
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Affiliation(s)
- Xincheng Wang
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Shuolun Wang
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
| | - Maria A Holland
- Department of Aerospace and Mechanical Engineering, University of Notre Dame, Notre Dame, IN 46556, USA.
- Bioengineering Graduate Program, University of Notre Dame, Notre Dame, IN 46556, USA
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Joy MSH, Nall DL, Emon B, Lee KY, Barishman A, Ahmed M, Rahman S, Selvin PR, Saif MTA. Synapses without tension fail to fire in an in vitro network of hippocampal neurons. Proc Natl Acad Sci U S A 2023; 120:e2311995120. [PMID: 38113266 PMCID: PMC10756289 DOI: 10.1073/pnas.2311995120] [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: 07/14/2023] [Accepted: 11/02/2023] [Indexed: 12/21/2023] Open
Abstract
Neurons in the brain communicate with each other at their synapses. It has long been understood that this communication occurs through biochemical processes. Here, we reveal that mechanical tension in neurons is essential for communication. Using in vitro rat hippocampal neurons, we find that 1) neurons become tout/tensed after forming synapses resulting in a contractile neural network, and 2) without this contractility, neurons fail to fire. To measure time evolution of network contractility in 3D (not 2D) extracellular matrix, we developed an ultrasensitive force sensor with 1 nN resolution. We employed Multi-Electrode Array and iGluSnFR, a glutamate sensor, to quantify neuronal firing at the network and at the single synapse scale, respectively. When neuron contractility is relaxed, both techniques show significantly reduced firing. Firing resumes when contractility is restored. This finding highlights the essential contribution of neural contractility in fundamental brain functions and has implications for our understanding of neural physiology.
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Affiliation(s)
- Md Saddam Hossain Joy
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Duncan L. Nall
- Department of Physics and Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Bashar Emon
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Ki Yun Lee
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Alexandra Barishman
- Department of Bioengineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Movviz Ahmed
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Saeedur Rahman
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - Paul R. Selvin
- Department of Physics and Center for Biophysics and Quantitative Biology, University of Illinois Urbana-Champaign, Urbana, IL61801
| | - M. Taher A. Saif
- Department of Mechanical Science and Engineering, University of Illinois Urbana-Champaign, Urbana, IL61801
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Raffa V. Force: A messenger of axon outgrowth. Semin Cell Dev Biol 2023; 140:3-12. [PMID: 35817654 DOI: 10.1016/j.semcdb.2022.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 07/05/2022] [Accepted: 07/05/2022] [Indexed: 01/28/2023]
Abstract
The axon is a sophisticated macromolecular machine composed of interrelated parts that transmit signals like spur gears transfer motion between parallel shafts. The growth cone is a fine sensor that integrates mechanical and chemical cues and transduces these signals through the generation of a traction force that pushes the tip and pulls the axon shaft forward. The axon shaft, in turn, senses this pulling force and transduces this signal in an orchestrated response, coordinating cytoskeleton remodeling and intercalated mass addition to sustain and support the advancing of the tip. Extensive research suggests that the direct application of active force is per se a powerful inducer of axon growth, potentially bypassing the contribution of the growth cone. This review provides a critical perspective on current knowledge of how the force is a messenger of axon growth and its mode of action for controlling navigation, including aspects that remain unclear. It also focuses on novel approaches and tools designed to mechanically manipulate axons, and discusses their implications in terms of potential novel therapies for re-wiring the nervous system.
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Affiliation(s)
- Vittoria Raffa
- Department of Biology, University of Pisa, SS12 Abetone e Brennero, 4, 56127 Pisa, Italy.
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6
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Chen W, He B. Actomyosin activity-dependent apical targeting of Rab11 vesicles reinforces apical constriction. J Cell Biol 2022; 221:213118. [DOI: 10.1083/jcb.202103069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 01/23/2022] [Accepted: 03/08/2022] [Indexed: 11/22/2022] Open
Abstract
During tissue morphogenesis, the changes in cell shape, resulting from cell-generated forces, often require active regulation of intracellular trafficking. How mechanical stimuli influence intracellular trafficking and how such regulation impacts tissue mechanics are not fully understood. In this study, we identify an actomyosin-dependent mechanism involving Rab11-mediated trafficking in regulating apical constriction in the Drosophila embryo. During Drosophila mesoderm invagination, apical actin and Myosin II (actomyosin) contractility induces apical accumulation of Rab11-marked vesicle-like structures (“Rab11 vesicles”) by promoting a directional bias in dynein-mediated vesicle transport. At the apical domain, Rab11 vesicles are enriched near the adherens junctions (AJs). The apical accumulation of Rab11 vesicles is essential to prevent fragmented apical AJs, breaks in the supracellular actomyosin network, and a reduction in the apical constriction rate. This Rab11 function is separate from its role in promoting apical Myosin II accumulation. These findings suggest a feedback mechanism between actomyosin activity and Rab11-mediated intracellular trafficking that regulates the force generation machinery during tissue folding.
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Affiliation(s)
- Wei Chen
- Department of Biological Sciences, Dartmouth College, Hanover, NH
| | - Bing He
- Department of Biological Sciences, Dartmouth College, Hanover, NH
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7
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Prolonged post-dural puncture headache and higher concentrations of prolactin: is there an association? Comment on Br J Anaesth 2021; 127: e204–e205. Br J Anaesth 2022; 128:e310-e311. [DOI: 10.1016/j.bja.2022.02.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/17/2022] [Accepted: 02/04/2022] [Indexed: 11/20/2022] Open
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Salbaum KA, Shelton ER, Serwane F. Retina organoids: Window into the biophysics of neuronal systems. BIOPHYSICS REVIEWS 2022; 3:011302. [PMID: 38505227 PMCID: PMC10903499 DOI: 10.1063/5.0077014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Accepted: 12/16/2021] [Indexed: 03/21/2024]
Abstract
With a kind of magnetism, the human retina draws the eye of neuroscientist and physicist alike. It is attractive as a self-organizing system, which forms as a part of the central nervous system via biochemical and mechanical cues. The retina is also intriguing as an electro-optical device, converting photons into voltages to perform on-the-fly filtering before the signals are sent to our brain. Here, we consider how the advent of stem cell derived in vitro analogs of the retina, termed retina organoids, opens up an exploration of the interplay between optics, electrics, and mechanics in a complex neuronal network, all in a Petri dish. This review presents state-of-the-art retina organoid protocols by emphasizing links to the biochemical and mechanical signals of in vivo retinogenesis. Electrophysiological recording of active signal processing becomes possible as retina organoids generate light sensitive and synaptically connected photoreceptors. Experimental biophysical tools provide data to steer the development of mathematical models operating at different levels of coarse-graining. In concert, they provide a means to study how mechanical factors guide retina self-assembly. In turn, this understanding informs the engineering of mechanical signals required to tailor the growth of neuronal network morphology. Tackling the complex developmental and computational processes in the retina requires an interdisciplinary endeavor combining experiment and theory, physics, and biology. The reward is enticing: in the next few years, retina organoids could offer a glimpse inside the machinery of simultaneous cellular self-assembly and signal processing, all in an in vitro setting.
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Affiliation(s)
| | - Elijah R. Shelton
- Faculty of Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, Munich, Germany
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Hoffe B, Holahan MR. Hyperacute Excitotoxic Mechanisms and Synaptic Dysfunction Involved in Traumatic Brain Injury. Front Mol Neurosci 2022; 15:831825. [PMID: 35283730 PMCID: PMC8907921 DOI: 10.3389/fnmol.2022.831825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/07/2022] [Indexed: 12/14/2022] Open
Abstract
The biological response of brain tissue to biomechanical strain are of fundamental importance in understanding sequela of a brain injury. The time after impact can be broken into four main phases: hyperacute, acute, subacute and chronic. It is crucial to understand the hyperacute neural outcomes from the biomechanical responses that produce traumatic brain injury (TBI) as these often result in the brain becoming sensitized and vulnerable to subsequent TBIs. While the precise physical mechanisms responsible for TBI are still a matter of debate, strain-induced shearing and stretching of neural elements are considered a primary factor in pathology; however, the injury-strain thresholds as well as the earliest onset of identifiable pathologies remain unclear. Dendritic spines are sites along the dendrite where the communication between neurons occurs. These spines are dynamic in their morphology, constantly changing between stubby, thin, filopodia and mushroom depending on the environment and signaling that takes place. Dendritic spines have been shown to react to the excitotoxic conditions that take place after an impact has occurred, with a shift to the excitatory, mushroom phenotype. Glutamate released into the synaptic cleft binds to NMDA and AMPA receptors leading to increased Ca2+ entry resulting in an excitotoxic cascade. If not properly cleared, elevated levels of glutamate within the synaptic cleft will have detrimental consequences on cellular signaling and survival of the pre- and post-synaptic elements. This review will focus on the synaptic changes during the hyperacute phase that occur after a TBI. With repetitive head trauma being linked to devastating medium – and long-term maladaptive neurobehavioral outcomes, including chronic traumatic encephalopathy (CTE), understanding the hyperacute cellular mechanisms can help understand the course of the pathology and the development of effective therapeutics.
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10
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Monnot P, Gangatharan G, Baraban M, Pottin K, Cabrera M, Bonnet I, Breau MA. Intertissue mechanical interactions shape the olfactory circuit in zebrafish. EMBO Rep 2022; 23:e52963. [PMID: 34889034 PMCID: PMC8811657 DOI: 10.15252/embr.202152963] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 11/15/2021] [Accepted: 11/18/2021] [Indexed: 02/05/2023] Open
Abstract
While the chemical signals guiding neuronal migration and axon elongation have been extensively studied, the influence of mechanical cues on these processes remains poorly studied in vivo. Here, we investigate how mechanical forces exerted by surrounding tissues steer neuronal movements and axon extension during the morphogenesis of the olfactory placode in zebrafish. We mainly focus on the mechanical contribution of the adjacent eye tissue, which develops underneath the placode through extensive evagination and invagination movements. Using quantitative analysis of cell movements and biomechanical manipulations, we show that the developing eye exerts lateral traction forces on the olfactory placode through extracellular matrix, mediating proper morphogenetic movements and axon extension within the placode. Our data shed new light on the key participation of intertissue mechanical interactions in the sculpting of neuronal circuits.
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Affiliation(s)
- Pauline Monnot
- Centre National de la Recherche Scientifique (CNRS)Institut de Biologie Paris‐Seine (IBPS)Developmental Biology LaboratorySorbonne UniversitéParisFrance,Institut CurieUniversité PSLSorbonne UniversitéCNRS UMR168Laboratoire Physico Chimie CurieParisFrance,Laboratoire Jean PerrinParisFrance
| | - Girisaran Gangatharan
- Centre National de la Recherche Scientifique (CNRS)Institut de Biologie Paris‐Seine (IBPS)Developmental Biology LaboratorySorbonne UniversitéParisFrance
| | - Marion Baraban
- Centre National de la Recherche Scientifique (CNRS)Institut de Biologie Paris‐Seine (IBPS)Developmental Biology LaboratorySorbonne UniversitéParisFrance,Laboratoire Jean PerrinParisFrance
| | - Karen Pottin
- Centre National de la Recherche Scientifique (CNRS)Institut de Biologie Paris‐Seine (IBPS)Developmental Biology LaboratorySorbonne UniversitéParisFrance
| | - Melody Cabrera
- Centre National de la Recherche Scientifique (CNRS)Institut de Biologie Paris‐Seine (IBPS)Developmental Biology LaboratorySorbonne UniversitéParisFrance
| | - Isabelle Bonnet
- Institut CurieUniversité PSLSorbonne UniversitéCNRS UMR168Laboratoire Physico Chimie CurieParisFrance
| | - Marie Anne Breau
- Centre National de la Recherche Scientifique (CNRS)Institut de Biologie Paris‐Seine (IBPS)Developmental Biology LaboratorySorbonne UniversitéParisFrance,Laboratoire Jean PerrinParisFrance,Institut National de la Santé et de la Recherche Médicale (INSERM)ParisFrance
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11
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Davies BM, Mowforth O, Gharooni AA, Tetreault L, Nouri A, Dhillon RS, Bednarik J, Martin AR, Young A, Takahashi H, Boerger TF, Newcombe VFJ, Zipser CM, Freund P, Koljonen PA, Rodrigues-Pinto R, Rahimi-Movaghar V, Wilson JR, Kurpad SN, Fehlings MG, Kwon BK, Harrop JS, Guest JD, Curt A, Kotter MRN. A New Framework for Investigating the Biological Basis of Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 5]: Mechanical Stress, Vulnerability and Time. Global Spine J 2022; 12:78S-96S. [PMID: 35174728 PMCID: PMC8859710 DOI: 10.1177/21925682211057546] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
STUDY DESIGN Literature Review (Narrative). OBJECTIVE To propose a new framework, to support the investigation and understanding of the pathobiology of DCM, AO Spine RECODE-DCM research priority number 5. METHODS Degenerative cervical myelopathy is a common and disabling spinal cord disorder. In this perspective, we review key knowledge gaps between the clinical phenotype and our biological models. We then propose a reappraisal of the key driving forces behind DCM and an individual's susceptibility, including the proposal of a new framework. RESULTS Present pathobiological and mechanistic knowledge does not adequately explain the disease phenotype; why only a subset of patients with visualized cord compression show clinical myelopathy, and the amount of cord compression only weakly correlates with disability. We propose that DCM is better represented as a function of several interacting mechanical forces, such as shear, tension and compression, alongside an individual's vulnerability to spinal cord injury, influenced by factors such as age, genetics, their cardiovascular, gastrointestinal and nervous system status, and time. CONCLUSION Understanding the disease pathobiology is a fundamental research priority. We believe a framework of mechanical stress, vulnerability, and time may better represent the disease as a whole. Whilst this remains theoretical, we hope that at the very least it will inspire new avenues of research that better encapsulate the full spectrum of disease.
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Affiliation(s)
| | - Oliver Mowforth
- Department of Neurosurgery, University of Cambridge, Cambridge, UK
| | | | - Lindsay Tetreault
- New York University, Langone Health, Graduate Medical Education, Department of Neurology, New York, NY, USA
| | - Aria Nouri
- Division of Neurosurgery, Geneva University Hospitals, University of Geneva, Genève, Switzerland
| | - Rana S. Dhillon
- Department of Neurosurgery, St Vincent’s Hospital Melbourne, Fitzroy, VIC, Australia
| | - Josef Bednarik
- Department of Neurology, University Hospital Brno and Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Allan R. Martin
- Department of Neurosurgery, University of California Davis, Sacramento, CA, USA
| | - Adam Young
- Department of Neurosurgery, University of Cambridge, Cambridge, UK
| | - Hitoshi Takahashi
- Department of Pathology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Timothy F. Boerger
- Department of Neurosurgery, Medical College of Wisconsin, Wauwatosa, WI, USA
| | - Virginia FJ Newcombe
- Division of Anaesthesia, Department of Medicine, University of Cambridge, Cambridge, UK
| | - Carl Moritz Zipser
- University Spine Center, Balgrist University Hospital, Zurich, Switzerland
| | - Patrick Freund
- University Spine Center, Balgrist University Hospital, Zurich, Switzerland
| | - Paul Aarne Koljonen
- Department of Orthopaedics and Traumatology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Ricardo Rodrigues-Pinto
- Spinal Unit (UVM), Department of Orthopaedics, Centro Hospitalar Universitário do Porto - Hospital de Santo António, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal
| | - Vafa Rahimi-Movaghar
- Department of Neurosurgery, Sina Trauma and Surgery Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Jefferson R. Wilson
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Shekar N Kurpad
- Department of Neurosurgery, Medical College of Wisconsin, Wauwatosa, WI, USA
| | - Michael G. Fehlings
- Division of Neurosurgery, Department of Surgery, University of Toronto, Toronto, ON, Canada
| | - Brian K. Kwon
- Vancouver Spine Surgery Institute, Department of Orthopedics, The University of British Columbia, Vancouver, BC, Canada
| | - James S. Harrop
- Department of Neurological Surgery, Thomas Jefferson University, Philadelphia, PA, USA
| | - James D. Guest
- Department of Neurosurgery and the Miami Project to Cure Paralysis, The Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Armin Curt
- University Spine Center, Balgrist University Hospital, Zurich, Switzerland
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Nasrin SR, Kabir AMR, Kakugo A. Cargo Transport by Microtubule-Associated Motor Protein Along Mechanically Deformed Microtubules. Methods Mol Biol 2022; 2430:291-302. [PMID: 35476340 DOI: 10.1007/978-1-0716-1983-4_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Mechanical forces play pivotal roles in regulating various cellular functions. Biomolecular motor protein-driven intracellular transportation is one example which is affected by mechanical forces, although the mechanism at molecular level is unknown. In this chapter, we describe deformation of microtubules under compressive stress and we show that such deformation of microtubules affects the kinetics of dynein-driven cargo transportation along the microtubules. The extent of alteration in the kinetics of dynein-driven transportation is found strongly dependent on the extent of deformation of microtubules under compressive stress.
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Affiliation(s)
| | | | - Akira Kakugo
- Faculty of Science, Hokkaido University, Sapporo, Hokkaido, Japan.
- Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido, Japan.
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13
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Mao F, Yang Y, Jiang H. Endocytosis and exocytosis protect cells against severe membrane tension variations. Biophys J 2021; 120:5521-5529. [PMID: 34838532 DOI: 10.1016/j.bpj.2021.11.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 10/20/2021] [Accepted: 11/15/2021] [Indexed: 01/07/2023] Open
Abstract
The ability of cells to regulate their shape and volume is critical for many cell functions. How endocytosis and exocytosis, as important ways of membrane trafficking, affect cellular volume regulation is still unclear. Here, we develop a theoretical framework to study the dynamics of cell volume, endocytosis, and exocytosis in response to osmotic shocks and mechanical loadings. This model can not only explain observed dynamics of endocytosis and exocytosis during osmotic shocks but also predict the dynamics of endocytosis and exocytosis during cell compressions. We find that a hypotonic shock stimulates exocytosis, while a hypertonic shock stimulates endocytosis; and exocytosis in turn allows cells to have a dramatic change in cell volume but a small change in membrane tension during hyposmotic swelling, protecting cells from rupture under high tension. In addition, we find that cell compressions with various loading speeds induce three distinct dynamic modes of endocytosis and exocytosis. Finally, we show that increasing endocytosis and exocytosis rates reduce the changes in cell volume and membrane tension under fast cell compression, whereas they enhance the changes in cell volume and membrane tension under slow cell compression. Together, our findings reveal critical roles of endocytosis and exocytosis in regulating cell volume and membrane tension.
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Affiliation(s)
- Fangtao Mao
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Complex System Mechanics, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui, China
| | - Yuehua Yang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Complex System Mechanics, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui, China.
| | - Hongyuan Jiang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Hefei National Laboratory for Physical Science at the Microscale, CAS Center for Excellence in Complex System Mechanics, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui, China.
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Motz CT, Kabat V, Saxena T, Bellamkonda RV, Zhu C. Neuromechanobiology: An Expanding Field Driven by the Force of Greater Focus. Adv Healthc Mater 2021; 10:e2100102. [PMID: 34342167 PMCID: PMC8497434 DOI: 10.1002/adhm.202100102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 07/06/2021] [Indexed: 12/14/2022]
Abstract
The brain processes information by transmitting signals through highly connected and dynamic networks of neurons. Neurons use specific cellular structures, including axons, dendrites and synapses, and specific molecules, including cell adhesion molecules, ion channels and chemical receptors to form, maintain and communicate among cells in the networks. These cellular and molecular processes take place in environments rich of mechanical cues, thus offering ample opportunities for mechanical regulation of neural development and function. Recent studies have suggested the importance of mechanical cues and their potential regulatory roles in the development and maintenance of these neuronal structures. Also suggested are the importance of mechanical cues and their potential regulatory roles in the interaction and function of molecules mediating the interneuronal communications. In this review, the current understanding is integrated and promising future directions of neuromechanobiology are suggested at the cellular and molecular levels. Several neuronal processes where mechanics likely plays a role are examined and how forces affect ligand binding, conformational change, and signal induction of molecules key to these neuronal processes are indicated, especially at the synapse. The disease relevance of neuromechanobiology as well as therapies and engineering solutions to neurological disorders stemmed from this emergent field of study are also discussed.
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Affiliation(s)
- Cara T Motz
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
| | - Victoria Kabat
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
| | - Tarun Saxena
- Department of Biomedical Engineering, Duke University, Durham, NC, 27709, USA
| | - Ravi V Bellamkonda
- Department of Biomedical Engineering, Pratt School of Engineering, Duke University, Durham, NC, 27708, USA
| | - Cheng Zhu
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- Parker H. Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332-0363, USA
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15
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Manipulation of Axonal Outgrowth via Exogenous Low Forces. Int J Mol Sci 2020; 21:ijms21218009. [PMID: 33126477 PMCID: PMC7663625 DOI: 10.3390/ijms21218009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 12/24/2022] Open
Abstract
Neurons are mechanosensitive cells. The role of mechanical force in the process of neurite initiation, elongation and sprouting; nerve fasciculation; and neuron maturation continues to attract considerable interest among scientists. Force is an endogenous signal that stimulates all these processes in vivo. The axon is able to sense force, generate force and, ultimately, transduce the force in a signal for growth. This opens up fascinating scenarios. How are forces generated and sensed in vivo? Which molecular mechanisms are responsible for this mechanotransduction signal? Can we exploit exogenously applied forces to mimic and control this process? How can these extremely low forces be generated in vivo in a non-invasive manner? Can these methodologies for force generation be used in regenerative therapies? This review addresses these questions, providing a general overview of current knowledge on the applications of exogenous forces to manipulate axonal outgrowth, with a special focus on forces whose magnitude is similar to those generated in vivo. We also review the principal methodologies for applying these forces, providing new inspiration and insights into the potential of this approach for future regenerative therapies.
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16
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Potekhina Y, Filatova A, Tregubova E, Mokhov D. Mechanosensitivity of Cells and Its Role in the Regulation of Physiological Functions and the Implementation of Physiotherapeutic Effects (Review). Sovrem Tekhnologii Med 2020; 12:77-89. [PMID: 34795996 PMCID: PMC8596276 DOI: 10.17691/stm2020.12.4.10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Indexed: 01/11/2023] Open
Abstract
Regulatory signals in the body are not limited to chemical and electrical ones. There is another type of important signals for cells: those are mechanical signals (coming from the environment or arising from within the body), which have been less known in the literature. The review summarizes new information on the mechanosensitivity of various cells of connective tissue and nervous system. Participation of mechanical stimuli in the regulation of growth, development, differentiation, and functioning of tissues is described. The data focus on bone remodeling, wound healing, neurite growth, and the formation of neural networks. Mechanotransduction, cellular organelles, and mechanosensitive molecules involved in these processes are discussed as well as the role of the extracellular matrix. The importance of mechanical characteristics of cells in the pathogenesis of diseases is highlighted. Finally, the possible role of mechanosensitivity in mediating the physiotherapeutic effects is addressed.
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Affiliation(s)
- Yu.P. Potekhina
- Professor, Department of Normal Physiology named after N.Y. Belenkov; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia
| | - A.I. Filatova
- Student, Faculty of Pediatrics; Privolzhsky Research Medical University, 10/1 Minin and Pozharsky Square, Nizhny Novgorod, 603005, Russia
| | - E.S. Tregubova
- Professor, Department of Osteopathy; North-Western State Medical University named after I.I. Mechnikov, 41 Kirochnaya St., Saint Petersburg, 191015, Russia; Associate Professor, Institute of Osteopathy; Saint Petersburg State University, 7/9 Universitetskaya naberezhnaya, Saint Petersburg, 199034, Russia
| | - D.E. Mokhov
- Head of the Department of Osteopathy; North-Western State Medical University named after I.I. Mechnikov, 41 Kirochnaya St., Saint Petersburg, 191015, Russia; Director of the Institute of Osteopathy Saint Petersburg State University, 7/9 Universitetskaya naberezhnaya, Saint Petersburg, 199034, Russia
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17
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18
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Sabharwal V, Koushika SP. Crowd Control: Effects of Physical Crowding on Cargo Movement in Healthy and Diseased Neurons. Front Cell Neurosci 2019; 13:470. [PMID: 31708745 PMCID: PMC6823667 DOI: 10.3389/fncel.2019.00470] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2019] [Accepted: 10/02/2019] [Indexed: 01/22/2023] Open
Abstract
High concentration of cytoskeletal filaments, organelles, and proteins along with the space constraints due to the axon's narrow geometry lead inevitably to intracellular physical crowding along the axon of a neuron. Local cargo movement is essential for maintaining steady cargo transport in the axon, and this may be impeded by physical crowding. Molecular motors that mediate active transport share movement mechanisms that allow them to bypass physical crowding present on microtubule tracks. Many neurodegenerative diseases, irrespective of how they are initiated, show increased physical crowding owing to the greater number of stalled organelles and structural changes associated with the cytoskeleton. Increased physical crowding may be a significant factor in slowing cargo transport to synapses, contributing to disease progression and culminating in the dying back of the neuronal process. This review explores the idea that physical crowding can impede cargo movement along the neuronal process. We examine the sources of physical crowding and strategies used by molecular motors that might enable cargo to circumvent physically crowded locations. Finally, we describe sub-cellular changes in neurodegenerative diseases that may alter physical crowding and discuss the implications of such changes on cargo movement.
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Affiliation(s)
| | - Sandhya P. Koushika
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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19
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Fan A, Joy MSH, Saif T. A connected cytoskeleton network generates axonal tension in embryonic Drosophila. LAB ON A CHIP 2019; 19:3133-3139. [PMID: 31435630 DOI: 10.1039/c9lc00243j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Axons of neurons are contractile, i.e., they actively maintain a rest tension. However, the spatial origin of this contractility along the axon and the role of the cytoskeleton in generating tension and sustaining rigidity are unknown. Here, using a microfluidic platform, we exposed a small segment of the axons of embryonic Drosophila motor neurons to specific cytoskeletal disruption drugs. We observed that a local actomyosin disruption led to a total loss in axonal tension, with the stiffness of the axon remaining unchanged. A local disruption of microtubules led to a local reduction in bending stiffness, while tension remained unchanged. These observations demonstrated that contractile forces are generated and transferred along the entire length of the axon in a serial fashion. Thus, a local force disruption results in a collapse of tension of the entire axon. This mechanism potentially provides a pathway for rapid tension regulation to facilitate physiological processes that are influenced by axonal tension.
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Affiliation(s)
- Anthony Fan
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
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20
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Gárate F, Pertusa M, Arana Y, Bernal R. Non-invasive Neurite Mechanics in Differentiated PC12 Cells. Front Cell Neurosci 2018; 12:194. [PMID: 30052690 PMCID: PMC6043779 DOI: 10.3389/fncel.2018.00194] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/17/2018] [Indexed: 01/04/2023] Open
Abstract
Thermal Fluctuations Spectroscopy (TFS) in combination with novel optical-based instrumentation was used to study mechanical properties of cell-cultured neurites with a spatial resolution limited only by the light diffraction. The analysis of thermal fluctuations together with a physical model of cellular elasticity allow us to determine relevant mechanical properties of neurite as axial tension σ, flexural rigidity B, plasma membrane tension γ, membrane bending rigidity K, and cytoskeleton to membrane-coupling ρbk, whose values are consistent with previously reported values measured using invasive approaches. The value obtained for the membrane-coupling parameter was used to estimate the average number of coupling elements between the plasma membrane and the cytoskeleton that fell in the range of 30 elements per area of the laser spot used to record the fluctuations. Furthermore, to expand the TFS analysis, we investigate the correlation between F-actin linear density and the mechanical features of PC12 neurites. Using a hybrid instrument that combines TFS and a simple fluorescent technique, our results show that the fluctuations are related with the F-actin concentration. These measurements have an advantage of not requiring the application of an external force, allowing as to directly establish a correlation between changes in the mechanical parameters and cytoskeleton-protein concentrations. The sensibility of our method was also tested by the application of TFS technique to PC12 neurite under Paraformaldehyde and Latrunculin-A effect. These results show a dramatic modification in the fluctuations that are consistent with the reported effect of these drugs, confirming the high sensitivity of this technique. Finally, the thermal fluctuation approach was applied to DRG axons to show that its utility is not limited to studies of PC12 neurites, but it is suitable to measure the general characteristic of various neuron-like cells.
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Affiliation(s)
- Fernanda Gárate
- Cellular Mechanics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile.,Biophysics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile
| | - María Pertusa
- Department of Biology, Millennium Nucleus of Ion Channels-Associated Diseases (MiNICAD), University of Santiago de Chile, Santiago, Chile
| | - Yahaira Arana
- Cellular Mechanics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile
| | - Roberto Bernal
- Cellular Mechanics Laboratory, Physics Department, SMAT-C, University of Santiago, Santiago, Chile
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21
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Gahl TJ, Kunze A. Force-Mediating Magnetic Nanoparticles to Engineer Neuronal Cell Function. Front Neurosci 2018; 12:299. [PMID: 29867315 PMCID: PMC5962660 DOI: 10.3389/fnins.2018.00299] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 04/18/2018] [Indexed: 12/12/2022] Open
Abstract
Cellular processes like membrane deformation, cell migration, and transport of organelles are sensitive to mechanical forces. Technically, these cellular processes can be manipulated through operating forces at a spatial precision in the range of nanometers up to a few micrometers through chaperoning force-mediating nanoparticles in electrical, magnetic, or optical field gradients. But which force-mediating tool is more suitable to manipulate cell migration, and which, to manipulate cell signaling? We review here the differences in forces sensation to control and engineer cellular processes inside and outside the cell, with a special focus on neuronal cells. In addition, we discuss technical details and limitations of different force-mediating approaches and highlight recent advancements of nanomagnetics in cell organization, communication, signaling, and intracellular trafficking. Finally, we give suggestions about how force-mediating nanoparticles can be used to our advantage in next-generation neurotherapeutic devices.
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Affiliation(s)
| | - Anja Kunze
- Department of Electrical and Computer Engineering, Montana State University, Bozeman, MT, United States
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22
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Michali-Stolarska M, Bladowska J, Stolarski M, Sąsiadek MJ. Diagnostic Imaging and Clinical Features of Intracranial Hypotension - Review of Literature. Pol J Radiol 2017; 82:842-849. [PMID: 29657653 PMCID: PMC5894032 DOI: 10.12659/pjr.904433] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2016] [Accepted: 03/24/2017] [Indexed: 12/02/2022] Open
Abstract
Intracranial hypotension (IH) is an uncommon, benign, and usually self-limiting condition caused by low cerebrospinal fluid (CSF) pressure, usually due to CSF leakage. The dominant clinical finding is an orthostatic headache. Other common clinical features include fever, nausea, vomiting, and tinnitus. Magnetic resonance imaging (MRI) plays an important role in the diagnosis and follow-up of patients with IH. Specific MRI findings include intracranial pachymeningeal enhancement, sagging of the brain, pituitary enlargement, and subdural fluid collections. Intracranial hypotension can mimic other conditions such as aseptic meningitis or pituitary adenomas. Differential diagnosis is important, because misdiagnosis may lead to unnecessary procedures and prolonged morbidity.
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Affiliation(s)
- Marta Michali-Stolarska
- Department of General and Interventional Radiology and Neuroradiology, Wrocław Medical University, Wrocław, Poland
| | - Joanna Bladowska
- Department of General and Interventional Radiology and Neuroradiology, Wrocław Medical University, Wrocław, Poland
| | - Mateusz Stolarski
- Department of Trauma Surgery, Knappschaftskrankenhaus Bochum-Langendreer, University Hospital Bochum, Bochum, Germany
| | - Marek J Sąsiadek
- Department of General and Interventional Radiology and Neuroradiology, Wrocław Medical University, Wrocław, Poland
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23
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Coupled circumferential and axial tension driven by actin and myosin influences in vivo axon diameter. Sci Rep 2017; 7:14188. [PMID: 29079766 PMCID: PMC5660205 DOI: 10.1038/s41598-017-13830-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 09/29/2017] [Indexed: 01/07/2023] Open
Abstract
It has long been known that neuronal axons are contractile. They actively maintain rest tension along the longitudinal direction both in vitro and in vivo. Here we show evidence that embryonic drosophila axons also actively maintain contractility/tension along the circumferential direction. We used confocal microscopy and spatial light interference microscopy to monitor axonal diameter along their length. We observed a decrease in diameter when microtubules are disrupted and an increase in diameter when actin filaments or myosin II are disrupted. Interestingly, active diameter reduction occurred consistently when axons were subjected to manipulations known to increase axial tension, suggesting that tension can be coupled in the axial and circumferential direction. This is further supported by the remarkably similar time constants for diameter reduction and rest tension increase of slackened axons. We infer that the actomyosin-driven circumferential contraction/hoop tension applies a squeezing force on the microtubule bundle of the axons. This hoop tension is balanced by the restoring force of the microtubule bundle. Therefore, axonal diameter increased when actin/myosin disrupting drugs relaxed the hoop tension and decreased when microtubule disrupting drug relaxed the restoring force. Circumferential tension thus can regulate axonal diameter and volume, as well as potentially microtubules alignment, inter-tubular spacing, and, by extension, axonal transport.
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24
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Smith JR, Lee J, Winkelstein BA. Nerve Root Compression Increases Spinal Astrocytic Vimentin in Parallel With Sustained Pain and Endothelial Vimentin in Association With Spinal Vascular Reestablishment. Spine (Phila Pa 1976) 2017; 42:1434-1439. [PMID: 28169954 PMCID: PMC5545166 DOI: 10.1097/brs.0000000000002103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Temporal immunohistochemistry analysis of spinal cord tissue from a rat model of cervical radiculopathy. OBJECTIVE The goal was to measure spinal endothelial and astrocytic vimentin expression after a painful nerve root compression to define spinal cellular expression of vimentin in the context of pain. SUMMARY OF BACKGROUND DATA The intermediate filament, vimentin, is expressed in a variety of cell types in the spinal cord and is modulated in response to neural pathologies. Early after nerve root compression spinal astrocytes become activated and blood-spinal cord barrier (BSCB) breakdown occurs in parallel with development of pain-related behaviors; these spinal responses remain activated as does the presence of pain. In addition to vimentin, glial fibrillary acidic protein (GFAP) expression is a hallmark of astrocyte activation. In contrast, vascular endothelial cells down-regulate vimentin expression in parallel with vascular breakdown. It is not known whether spinal astrocytes and endothelial cells modulate their expression of vimentin in response to a painful neural injury. METHODS Mechanical hyperalgesia was measured and spinal cord tissue was harvested at days 1 and 7 after a unilateral nerve root compression in rats. Vimentin was coimmunolabeled with GFAP to label astrocytes and von Willebrand factor (VWF) for endothelial cells in the spinal cord on the side of injury. RESULTS Spinal astrocytic vimentin increases by day 7 after nerve root compression, corresponding to when mechanical hyperalgesia is maintained. Spinal endothelial vimentin increases as early as day 1 after a painful compression and is even more robust at day 7. CONCLUSION The delayed elevation in spinal astrocytic vimentin corresponding to sustained mechanical hyperalgesia supports its having a relationship with pain maintenance. Further, since BSCB integrity has been shown to be reestablished by day 7 after a painful compression, endothelial expressed vimentin may help to fortify spinal vasculature contributing to BSCB stability. LEVEL OF EVIDENCE N/A.
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Affiliation(s)
- Jenell R. Smith
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jasmine Lee
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Beth A. Winkelstein
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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25
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Mechanism of Axonal Contractility in Embryonic Drosophila Motor Neurons In Vivo. Biophys J 2017; 111:1519-1527. [PMID: 27705774 PMCID: PMC5052456 DOI: 10.1016/j.bpj.2016.08.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 11/24/2022] Open
Abstract
Several in vitro and limited in vivo experiments have shown that neurons maintain a rest tension along their axons intrinsically. They grow in response to stretch but contract in response to loss of tension. This contraction eventually leads to the restoration of the rest tension in axons. However, the mechanism by which axons maintain tension in vivo remains elusive. The objective of this work is to elucidate the key cytoskeletal components responsible for generating tension in axons. Toward this goal, in vivo experiments were conducted on single axons of embryonic Drosophila motor neurons in the presence of various drugs. Each axon was slackened mechanically by bringing the neuromuscular junction toward the central nervous system multiple times. In the absence of any drug, axons shortened and restored the straight configuration within 2–4 min of slackening. The total shortening was ∼40% of the original length. The recovery rate in each cycle, but not the recovery magnitude, was dependent on the axon’s prior contraction history. For example, the contraction time of a previously slackened axon may be twice its first-time contraction. This recovery was significantly hampered with the depletion of ATP, inhibition of myosin motors, and disruption of actin filaments. The disruption of microtubules did not affect the recovery magnitude, but, on the contrary, led to an enhanced recovery rate compared to control cases. These results suggest that the actomyosin machinery is the major active element in axonal contraction, whereas microtubules contribute as resistive/dissipative elements.
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26
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Guillaud L, Dimitrov D, Takahashi T. Presynaptic morphology and vesicular composition determine vesicle dynamics in mouse central synapses. eLife 2017; 6. [PMID: 28432787 PMCID: PMC5423771 DOI: 10.7554/elife.24845] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 04/18/2017] [Indexed: 11/13/2022] Open
Abstract
Transport of synaptic vesicles (SVs) in nerve terminals is thought to play essential roles in maintenance of neurotransmission. To identify factors modulating SV movements, we performed real-time imaging analysis of fluorescently labeled SVs in giant calyceal and conventional hippocampal terminals. Compared with small hippocampal terminals, SV movements in giant calyceal terminals were faster, longer and kinetically more heterogeneous. Morphological maturation of giant calyceal terminals was associated with an overall reduction in SV mobility and displacement heterogeneity. At the molecular level, SVs over-expressing vesicular glutamate transporter 1 (VGLUT1) showed higher mobility than VGLUT2-expressing SVs. Pharmacological disruption of the presynaptic microtubule network preferentially reduced long directional movements of SVs between release sites. Functionally, synaptic stimulation appeared to recruit SVs to active zones without significantly altering their mobility. Hence, the morphological features of nerve terminals and the molecular signature of vesicles are key elements determining vesicular dynamics and movements in central synapses.
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Affiliation(s)
- Laurent Guillaud
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Dimitar Dimitrov
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Tomoyuki Takahashi
- Cellular and Molecular Synaptic Function Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
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27
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Kunze A, Murray CT, Godzich C, Lin J, Owsley K, Tay A, Di Carlo D. Modulating motility of intracellular vesicles in cortical neurons with nanomagnetic forces on-chip. LAB ON A CHIP 2017; 17:842-854. [PMID: 28164203 PMCID: PMC5400667 DOI: 10.1039/c6lc01349j] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Vesicle transport is a major underlying mechanism of cell communication. Inhibiting vesicle transport in brain cells results in blockage of neuronal signals, even in intact neuronal networks. Modulating intracellular vesicle transport can have a huge impact on the development of new neurotherapeutic concepts, but only if we can specifically interfere with intracellular transport patterns. Here, we propose to modulate motion of intracellular lipid vesicles in rat cortical neurons based on exogenously bioconjugated and cell internalized superparamagnetic iron oxide nanoparticles (SPIONs) within microengineered magnetic gradients on-chip. Upon application of 6-126 pN on intracellular vesicles in neuronal cells, we explored how the magnetic force stimulus impacts the motion pattern of vesicles at various intracellular locations without modulating the entire cell morphology. Altering vesicle dynamics was quantified using, mean square displacement, a caging diameter and the total traveled distance. We observed a de-acceleration of intercellular vesicle motility, while applying nanomagnetic forces to cultured neurons with SPIONs, which can be explained by a decrease in motility due to opposing magnetic force direction. Ultimately, using nanomagnetic forces inside neurons may permit us to stop the mis-sorting of intracellular organelles, proteins and cell signals, which have been associated with cellular dysfunction. Furthermore, nanomagnetic force applications will allow us to wirelessly guide axons and dendrites by exogenously using permanent magnetic field gradients.
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Affiliation(s)
- Anja Kunze
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA. and Department of Electrical and Computer Engineering, Montana State University, Bozeman, Montana 59717, USA.
| | - Coleman Tylor Murray
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA.
| | - Chanya Godzich
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA.
| | - Jonathan Lin
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA.
| | - Keegan Owsley
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA.
| | - Andy Tay
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA.
| | - Dino Di Carlo
- Department of Bioengineering, University of California, Los Angeles, California 90095, USA. and California NanoSystems Institute, University of California, Los Angeles, California 90095, USA and Jonsson Comprehensive Cancer Research Center, University of California, Los Angeles, California 90095, USA
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28
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A neuron-in-capillary platform for facile collection and mass spectrometric characterization of a secreted neuropeptide. Sci Rep 2016; 6:26940. [PMID: 27245782 PMCID: PMC4887886 DOI: 10.1038/srep26940] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/10/2016] [Indexed: 12/21/2022] Open
Abstract
The integration of microfluidic devices—which efficiently handle small liquid volumes—with separations/mass spectrometry (MS) is an effective approach for profiling the neurochemistry occurring in selected neurons. Interfacing the microfluidic cell culture to the mass spectrometer is challenging because of geometric and scaling issues. Here we demonstrate the hyphenation of a neuron-in-capillary platform to a solid phase extraction device and off-line MS. A primary neuronal culture of Aplysia californica neurons was established directly inside a cylindrical polyimide capillary. The approach also uses a particle-embedded monolith to condition neuropeptide releasates collected from several Aplysia neurons cultured in the capillary, with the subsequent characterization of released peptides via MS. This system presents a number of advances compared to more traditional microfluidic devices fabricated with polydimethylsiloxane. These include low cost, easy access to cell culture, rigidity, ease of transport, and minimal fluid handling. The cylindrical geometry of the platform allows convenient interface with a wide range of analytical tools that utilize capillary columns.
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29
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Gárate F, Betz T, Pertusa M, Bernal R. Time-resolved neurite mechanics by thermal fluctuation assessments. Phys Biol 2015; 12:066020. [PMID: 26717293 DOI: 10.1088/1478-3975/12/6/066020] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the absence of simple noninvasive measurements, the knowledge of temporal and spatial variations of axons mechanics remains scarce. By extending thermal fluctuation spectroscopy (TFS) to long protrusions, we determine the transverse amplitude thermal fluctuation spectra that allow direct and simultaneous access to three key mechanics parameters: axial tension, bending flexural rigidity and plasma membrane tension. To test our model, we use PC12 cell protrusions-a well-know biophysical model of axons-in order to simplify the biological system under scope. For instance, axial and plasma membrane tension are found in the range of nano Newton and tens of pico Newtons per micron respectively. Furthermore, our results shows that the TFS technique is capable to distinguish quasi-identical protrusions. Another advantage of our approach is the time resolved nature of the measurements. Indeed, in the case of long term experiments on PC12 protrusions, TFS has revealed large temporal, correlated variations of the protrusion mechanics, displaying extraordinary feedback control over the axial tension in order to maintain a constant tension value.
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Affiliation(s)
- Fernanda Gárate
- Departamento de Física and SMAT-C, Universidad de Santiago de Chile, 9170124 Santiago, Chile
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30
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Fan A, Stebbings KA, Llano DA, Saif T. Stretch induced hyperexcitability of mice callosal pathway. Front Cell Neurosci 2015; 9:292. [PMID: 26300729 PMCID: PMC4525056 DOI: 10.3389/fncel.2015.00292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/15/2015] [Indexed: 01/09/2023] Open
Abstract
Memory and learning are thought to result from changes in synaptic strength. Previous studies on synaptic physiology in brain slices have traditionally been focused on biochemical processes. Here, we demonstrate with experiments on mouse brain slices that central nervous system plasticity is also sensitive to mechanical stretch. This is important, given the host of clinical conditions involving changes in mechanical tension on the brain, and the normal role that mechanical tension plays in brain development. A novel platform is developed to investigate neural responses to mechanical stretching. Flavoprotein autofluoresence (FA) imaging was employed for measuring neural activity. We observed that synaptic excitability substantially increases after a small (2.5%) stretch was held for 10 min and released. The increase is accumulative, i.e., multiple stretch cycles further increase the excitability. We also developed analytical tools to quantify the spatial spread and response strength. Results show that the spatial spread is less stable in slices undergoing the stretch-unstretch cycle. FA amplitude and activation rate decrease as excitability increases in stretch cases but not in electrically enhanced cases. These results collectively demonstrate that a small stretch in physiological range can modulate neural activities significantly, suggesting that mechanical events can be employed as a novel tool for the modulation of neural plasticity.
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Affiliation(s)
- Anthony Fan
- Department of Mechanical Science and Engineering, University of Illinois Urbana, IL, USA
| | | | - Daniel A Llano
- Neuroscience Program, University of Illinois Urbana, IL, USA ; Department of Molecular and Integrative Physiology, University of Illinois Urbana, IL, USA ; Beckman Institute, University of Illinois Urbana, IL, USA ; College of Medicine, University of Illinois Urbana, IL, USA
| | - Taher Saif
- Department of Mechanical Science and Engineering, University of Illinois Urbana, IL, USA
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Mosca TJ. On the Teneurin track: a new synaptic organization molecule emerges. Front Cell Neurosci 2015; 9:204. [PMID: 26074772 PMCID: PMC4444827 DOI: 10.3389/fncel.2015.00204] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2015] [Accepted: 05/11/2015] [Indexed: 11/16/2022] Open
Abstract
To achieve proper synaptic development and function, coordinated signals must pass between the pre- and postsynaptic membranes. Such transsynaptic signals can be comprised of receptors and secreted ligands, membrane associated receptors, and also pairs of synaptic cell adhesion molecules. A critical open question bridging neuroscience, developmental biology, and cell biology involves identifying those signals and elucidating how they function. Recent work in Drosophila and vertebrate systems has implicated a family of proteins, the Teneurins, as a new transsynaptic signal in both the peripheral and central nervous systems. The Teneurins have established roles in neuronal wiring, but studies now show their involvement in regulating synaptic connections between neurons and bridging the synaptic membrane and the cytoskeleton. This review will examine the Teneurins as synaptic cell adhesion molecules, explore how they regulate synaptic organization, and consider how some consequences of human Teneurin mutations may have synaptopathic origins.
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Affiliation(s)
- Timothy J Mosca
- Department of Biology, Stanford University Stanford, CA, USA
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Schievink WI, Nuño M, Rozen TD, Maya MM, Mamelak AN, Carmichael J, Bonert VS. Hyperprolactinemia due to spontaneous intracranial hypotension. J Neurosurg 2015; 122:1020-5. [DOI: 10.3171/2014.9.jns132687] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECT
Spontaneous intracranial hypotension is an increasingly recognized cause of headaches. Pituitary enlargement and brain sagging are common findings on MRI in patients with this disorder. The authors therefore investigated pituitary function in patients with spontaneous intracranial hypotension.
METHODS
Pituitary hormones were measured in a group of 42 consecutive patients with spontaneous intracranial hypotension. For patients with hyperprolactinemia, prolactin levels also were measured following treatment. Magnetic resonance imaging was performed prior to and following treatment.
RESULTS
The study group consisted of 27 women and 15 men with a mean age at onset of symptoms of 52.2 ± 10.7 years (mean ± SD; range 17–72 years). Hyperprolactinemia was detected in 10 patients (24%), ranging from 16 ng/ml to 96.6 ng/ml in men (normal range 3–14.7 ng/ml) and from 31.3 ng/ml to 102.5 ng/ml in women (normal range 3.8–23.2 ng/ml). In a multivariate analysis, only brain sagging on MRI was associated with hyperprolactinemia. Brain sagging was present in 60% of patients with hyperprolactinemia and in 19% of patients with normal prolactin levels (p = 0.02). Following successful treatment of the spontaneous intracranial hypotension, hyperprolactinemia resolved, along with normalization of brain MRI findings in all 10 patients.
CONCLUSIONS
Spontaneous intracranial hypotension is a previously undescribed cause of hyperprolactinemia. Brain sagging causing distortion of the pituitary stalk (stalk effect) may be responsible for the hyperprolactinemia.
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Affiliation(s)
| | | | - Todd D. Rozen
- 2Department of Neurology, Geisinger Wyoming Valley Medical Center, Wilkes-Barre, Pennsylvania
| | | | | | - John Carmichael
- 4Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, California; and
| | - Vivien S. Bonert
- 4Pituitary Center, Cedars-Sinai Medical Center, Los Angeles, California; and
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Mueller JK, Tyler WJ. A quantitative overview of biophysical forces impinging on neural function. Phys Biol 2014; 11:051001. [DOI: 10.1088/1478-3975/11/5/051001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Ahmed WW, Saif TA. Active transport of vesicles in neurons is modulated by mechanical tension. Sci Rep 2014; 4:4481. [PMID: 24670781 PMCID: PMC3967286 DOI: 10.1038/srep04481] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 02/24/2014] [Indexed: 11/19/2022] Open
Abstract
Effective intracellular transport of proteins and organelles is critical in cells, and is especially important for ensuring proper neuron functionality. In neurons, most proteins are synthesized in the cell body and must be transported through thin structures over long distances where normal diffusion is insufficient. Neurons transport subcellular cargo along axons and neurites through a stochastic interplay of active and passive transport. Mechanical tension is critical in maintaining proper function in neurons, but its role in transport is not well understood. To this end, we investigate the active and passive transport of vesicles in Aplysia neurons while changing neurite tension via applied strain, and quantify the resulting dynamics. We found that tension in neurons modulates active transport of vesicles by increasing the probability of active motion, effective diffusivity, and induces a retrograde bias. We show that mechanical tension modulates active transport processes in neurons and that external forces can couple to internal (subcellular) forces and change the overall transport dynamics.
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Affiliation(s)
- Wylie W Ahmed
- 1] Department of Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801 [2]
| | - Taher A Saif
- Department of Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801
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Abstract
The development of the nervous system has so far, to a large extent, been considered in the context of biochemistry, molecular biology and genetics. However, there is growing evidence that many biological systems also integrate mechanical information when making decisions during differentiation, growth, proliferation, migration and general function. Based on recent findings, I hypothesize that several steps during nervous system development, including neural progenitor cell differentiation, neuronal migration, axon extension and the folding of the brain, rely on or are even driven by mechanical cues and forces.
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Affiliation(s)
- Kristian Franze
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.
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Lee CY, Romanova EV, Sweedler JV. Laminar stream of detergents for subcellular neurite damage in a microfluidic device: a simple tool for the study of neuroregeneration. J Neural Eng 2013; 10:036020. [PMID: 23656702 DOI: 10.1088/1741-2560/10/3/036020] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
OBJECTIVE The regeneration and repair of damaged neuronal networks is a difficult process to study in vivo, leading to the development of multiple in vitro models and techniques for studying nerve injury. Here we describe an approach for generating a well-defined subcellular neurite injury in a microfluidic device. APPROACH A defined laminar stream of sodium dodecyl sulfate (SDS) was used to damage selected portions of neurites of individual neurons. The somata and neurites unaffected by the SDS stream remained viable, thereby enabling the study of neuronal regeneration. MAIN RESULTS By using well-characterized neurons from Aplysia californica cultured in vitro, we demonstrate that our approach is useful in creating neurite damage, investigating neurotrophic factors, and monitoring somata migration during regeneration. Supplementing the culture medium with acetylcholinesterase (AChE) or Aplysia hemolymph facilitated the regeneration of the peptidergic Aplysia neurons within 72 h, with longer (p < 0.05) and more branched (p < 0.05) neurites than in the control medium. After the neurons were transected, their somata migrated; intriguingly, for the control cultures, the migration direction was always away from the injury site (7/7). In the supplemented cultures, the number decreased to 6/8 in AChE and 4/8 in hemolymph, with reduced migration distances in both cases. SIGNIFICANCE The SDS transection approach is simple and inexpensive, yet provides flexibility in studying neuroregeneration, particularly when it is important to make sure there are no retrograde signals from the distal segments affecting regeneration. Neurons are known to not only be under tension but also balanced in terms of force, and the balance is obviously disrupted by transection. Our experimental platform, verified with Aplysia, can be extended to mammalian systems, and help us gain insight into the role that neurotrophic factors and mechanical tension play during neuronal regeneration.
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Affiliation(s)
- Chang Young Lee
- School of Nano-Bioscience and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea
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Ahmed WW, Williams BJ, Silver AM, Saif TA. Measuring nonequilibrium vesicle dynamics in neurons under tension. LAB ON A CHIP 2013; 13:570-578. [PMID: 23303380 DOI: 10.1039/c2lc41109a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Vesicle transport in neurons is a highly complex nonequilibrium process. Their subcellular environment is undergoing constant fluctuations from thermal energy and molecular motors. Vesicle transport is an interplay between random motion (passive) and directed motion (active) driven by molecular motors along cytoskeletal filaments. It has been shown that growth, guidance, and vesicle dynamics of neurons is affected by mechanical tension. Here we present a method to analyze vesicle transport via a temporal Mean Square Displacement (tMSD) analysis while applying mechanical strain to neurons. The tMSD analysis allows characterization of active and passive vesicle motion as well as many other parameters including: power law scaling, velocity, direction, and flux. Our results suggest: (1) The tMSD analysis is able to capture vesicle motion alternating between passive and active states, and indicates that vesicle motion in Aplysia neurons is primarily passive (exhibiting active motion for ~8% of the time). (2) Under mechanical stretch (increased neurite tension), active transport of vesicles increases to ~13%, while vesicle velocity remains unchanged. (3) Upon unstretching (decreased tension), the level of active transport returns to normal but vesicle velocity decreases. These results suggest that vesicle transport in neurons is highly sensitive to mechanical stimulation. Our method allows precise characterization of vesicle dynamics in response to applied mechanical strain.
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Affiliation(s)
- Wylie W Ahmed
- Department of Mechanical Science and Engineering, University of Illinois, Urbana, IL 61801, USA
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