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van Tartwijk FW, Wunderlich LCS, Mela I, Makarchuk S, Jakobs MAH, Qamar S, Franze K, Kaminski Schierle GS, St George-Hyslop PH, Lin JQ, Holt CE, Kaminski CF. Mutation of the ALS-/FTD-Associated RNA-Binding Protein FUS Affects Axonal Development. J Neurosci 2024; 44:e2148232024. [PMID: 38692734 PMCID: PMC7616130 DOI: 10.1523/jneurosci.2148-23.2024] [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: 11/14/2023] [Revised: 02/23/2024] [Accepted: 03/29/2024] [Indexed: 05/03/2024] Open
Abstract
Aberrant condensation and localization of the RNA-binding protein (RBP) fused in sarcoma (FUS) occur in variants of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Changes in RBP function are commonly associated with changes in axonal cytoskeletal organization and branching in neurodevelopmental disorders. Here, we asked whether branching defects also occur in vivo in a model of FUS-associated disease. We use two reported Xenopus models of ALS/FTD (of either sex), the ALS-associated mutant FUS(P525L) and a mimic of hypomethylated FUS, FUS(16R). Both mutants strongly reduced axonal complexity in vivo. We also observed an axon looping defect for FUS(P525L) in the target area, which presumably arises due to errors in stop cue signaling. To assess whether the loss of axon complexity also had a cue-independent component, we assessed axonal cytoskeletal integrity in vitro. Using a novel combination of fluorescence and atomic force microscopy, we found that mutant FUS reduced actin density in the growth cone, altering its mechanical properties. Therefore, FUS mutants may induce defects during early axonal development.
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Affiliation(s)
- Francesca W van Tartwijk
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
| | - Lucia C S Wunderlich
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
| | - Ioanna Mela
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
| | - Stanislaw Makarchuk
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge CB2 OAH, United Kingdom
| | - Maximilian A H Jakobs
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Seema Qamar
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
| | - Kristian Franze
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Gabriele S Kaminski Schierle
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
| | - Peter H St George-Hyslop
- Department of Clinical Neurosciences, Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, United Kingdom
- Department of Medicine, University of Toronto and University Health Network and Tanz Centre for Research in Neurodegenerative Diseases University of Toronto, Toronto, Ontario M5T 0S8, Canada
- Department of Neurology, Taub Institute For Research on Alzheimer's Disease and the Aging Brain, Columbia University Irvine Medical Center, New York, New York 10032
| | - Julie Qiaojin Lin
- Department of Clinical Neurosciences, UK Dementia Research Institute, University of Cambridge, Cambridge CB2 OAH, United Kingdom
- UK Dementia Research Institute Centre and Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London SE5 9NU, United Kingdom
| | - Christine E Holt
- Department of Physiology, Development, and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
| | - Clemens F Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, United Kingdom
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2
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Kasuba KC, Buccino AP, Bartram J, Gaub BM, Fauser FJ, Ronchi S, Kumar SS, Geissler S, Nava MM, Hierlemann A, Müller DJ. Mechanical stimulation and electrophysiological monitoring at subcellular resolution reveals differential mechanosensation of neurons within networks. NATURE NANOTECHNOLOGY 2024; 19:825-833. [PMID: 38378885 PMCID: PMC11186759 DOI: 10.1038/s41565-024-01609-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Accepted: 01/12/2024] [Indexed: 02/22/2024]
Abstract
A growing consensus that the brain is a mechanosensitive organ is driving the need for tools that mechanically stimulate and simultaneously record the electrophysiological response of neurons within neuronal networks. Here we introduce a synchronized combination of atomic force microscopy, high-density microelectrode array and fluorescence microscopy to monitor neuronal networks and to mechanically characterize and stimulate individual neurons at piconewton force sensitivity and nanometre precision while monitoring their electrophysiological activity at subcellular spatial and millisecond temporal resolution. No correlation is found between mechanical stiffness and electrophysiological activity of neuronal compartments. Furthermore, spontaneously active neurons show exceptional functional resilience to static mechanical compression of their soma. However, application of fast transient (∼500 ms) mechanical stimuli to the neuronal soma can evoke action potentials, which depend on the anchoring of neuronal membrane and actin cytoskeleton. Neurons show higher responsivity, including bursts of action potentials, to slower transient mechanical stimuli (∼60 s). Moreover, transient and repetitive application of the same compression modulates the neuronal firing rate. Seemingly, neuronal networks can differentiate and respond to specific characteristics of mechanical stimulation. Ultimately, the developed multiparametric tool opens the door to explore manifold nanomechanobiological responses of neuronal systems and new ways of mechanical control.
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Affiliation(s)
| | | | - Julian Bartram
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | - Benjamin M Gaub
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | - Felix J Fauser
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | | | | | - Sydney Geissler
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | - Michele M Nava
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | - Andreas Hierlemann
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland.
| | - Daniel J Müller
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland.
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3
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Ding EA, Kumar S. Neurofilament Biophysics: From Structure to Biomechanics. Mol Biol Cell 2024; 35:re1. [PMID: 38598299 PMCID: PMC11151108 DOI: 10.1091/mbc.e23-11-0438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 03/25/2024] [Accepted: 04/04/2024] [Indexed: 04/12/2024] Open
Abstract
Neurofilaments (NFs) are multisubunit, neuron-specific intermediate filaments consisting of a 10-nm diameter filament "core" surrounded by a layer of long intrinsically disordered protein (IDP) "tails." NFs are thought to regulate axonal caliber during development and then stabilize the mature axon, with NF subunit misregulation, mutation, and aggregation featuring prominently in multiple neurological diseases. The field's understanding of NF structure, mechanics, and function has been deeply informed by a rich variety of biochemical, cell biological, and mouse genetic studies spanning more than four decades. These studies have contributed much to our collective understanding of NF function in axonal physiology and disease. In recent years, however, there has been a resurgence of interest in NF subunit proteins in two new contexts: as potential blood- and cerebrospinal fluid-based biomarkers of neuronal damage, and as model IDPs with intriguing properties. Here, we review established principles and more recent discoveries in NF structure and function. Where possible, we place these findings in the context of biophysics of NF assembly, interaction, and contributions to axonal mechanics.
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Affiliation(s)
- Erika A. Ding
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
| | - Sanjay Kumar
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA 94158
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4
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Procès A, Alpizar YA, Halliez S, Brône B, Saudou F, Ris L, Gabriele S. Stretch-injury promotes microglia activation with enhanced phagocytic and synaptic stripping activities. Biomaterials 2024; 305:122426. [PMID: 38134473 DOI: 10.1016/j.biomaterials.2023.122426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 11/29/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023]
Abstract
Microglial cells, as the primary defense line in the central nervous system, play a crucial role in responding to various mechanical signals that can trigger their activation. Despite extensive research on the impact of chemical signaling on brain cells, the understanding of mechanical signaling in microglia remains limited. To bridge this gap, we subjected microglial cells to a singular mechanical stretch and compared their responses with those induced by lipopolysaccharide treatment, a well-established chemical activator. Here we show that stretching microglial cells leads to their activation, highlighting their significant mechanosensitivity. Stretched microglial cells exhibited distinct features, including elevated levels of Iba1 protein, a denser actin cytoskeleton, and increased persistence in migration. Unlike LPS-treated microglial cells, the secretory profile of chemokines and cytokines remained largely unchanged in response to stretching, except for TNF-α. Intriguingly, a single stretch injury resulted in more compacted chromatin and DNA damage, suggesting potential long-term genomic instabilities in stretched microglia. Using compartmentalized microfluidic chambers with neuronal networks, we observed that stretched microglial cells exhibited enhanced phagocytic and synaptic stripping activities. These findings collectively suggest that stretching events can unlock the immune potential of microglial cells, contributing to the maintenance of brain tissue homeostasis following mechanical injury.
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Affiliation(s)
- Anthony Procès
- Mechanobiology & Biomaterials Group, CIRMAP, Research Institute for Biosciences, University of Mons, B-7000, Mons, Belgium; Neuroscience Laboratory, Neuroscience Department, Research Institute for Biosciences, University of Mons, B-7000, Mons, Belgium
| | - Yeranddy A Alpizar
- Neurophysiology Laboratory, BIOMED Research Institute, UHasselt, B-3500, Hasselt, Belgium
| | - Sophie Halliez
- Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, F-59000, Lille, France
| | - Bert Brône
- Neurophysiology Laboratory, BIOMED Research Institute, UHasselt, B-3500, Hasselt, Belgium
| | - Frédéric Saudou
- Univ. Grenoble Alpes, Inserm, U1216, CHU Grenoble Alpes, Grenoble Institut Neuroscience, F-38000, Grenoble, France
| | - Laurence Ris
- Neuroscience Laboratory, Neuroscience Department, Research Institute for Biosciences, University of Mons, B-7000, Mons, Belgium
| | - Sylvain Gabriele
- Mechanobiology & Biomaterials Group, CIRMAP, Research Institute for Biosciences, University of Mons, B-7000, Mons, Belgium.
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5
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Wasnik K, Gupta PS, Mukherjee S, Oviya A, Prakash R, Pareek D, Patra S, Maity S, Rai V, Singh M, Singh G, Yadav DD, Das S, Maiti P, Paik P. Poly( N-acryloylglycine-acrylamide) Hydrogel Mimics the Cellular Microenvironment and Promotes Neurite Growth with Protection from Oxidative Stress. ACS APPLIED BIO MATERIALS 2023; 6:5644-5661. [PMID: 37993284 DOI: 10.1021/acsabm.3c00807] [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: 11/24/2023]
Abstract
In this work, the glycine-based acryloyl monomer is polymerized to obtain a neurogenic polymeric hydrogel for regenerative applications. The synthesized poly(N-acryloylglycine-acrylamide) [poly(NAG-b-A)] nanohydrogel exhibits high swelling (∼1500%) and is mechanically very stable, biocompatible, and proliferative in nature. The poly(NAG-b-A) nanohydrogel provides a stable 3D extracellular mimetic environment and promotes healthy neurite growth for primary cortical neurons by facilitating cellular adhesion, proliferation, actin filament stabilization, and neuronal differentiation. Furthermore, the protective role of the poly(NAG-b-A) hydrogel for the neurons in oxidative stress conditions is revealed and it is found that it is a clinically relevant material for neuronal regenerative applications, such as for promoting nerve regeneration via GSK3β inhibition. This hydrogel additionally plays an important role in modulating the biological microenvironment, either as an agonist and antagonist or as an antioxidant. Furthermore, it favors the physiological responses and eases the neurite growth efficiency. Additionally, we found out that the conversion of glycine-based acryloyl monomers into their corresponding polymer modulates the mechanical performance, mimics the cellular microenvironment, and accelerates the self-healing capability due to the responsive behavior towards reactive oxygen species (ROS). Thus, the p(NAG-b-A) hydrogel could be a potential candidate to induce neuronal regeneration since it provides a physical cue and significantly boosts neurite outgrowth and also maintains the microtubule integrity in neuronal cells.
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Affiliation(s)
- Kirti Wasnik
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Prem Shankar Gupta
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Sudip Mukherjee
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Alagu Oviya
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Ravi Prakash
- School of Material Science, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Divya Pareek
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Sukanya Patra
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Somedutta Maity
- School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad, Telangana State 500 046, India
| | - Vipin Rai
- Department of Biochemistry, Institute of Sciences, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Monika Singh
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Gurmeet Singh
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Desh Deepak Yadav
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Santanu Das
- Department of Ceramic Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Pralay Maiti
- School of Material Science, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
| | - Pradip Paik
- School of Biomedical Engineering, Indian Institute of Technology, Banaras Hindu University (BHU), Varanasi, Uttar Pradesh 221 005, India
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6
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Schneider SE, Scott AK, Seelbinder B, Elzen CVD, Wilson RL, Miller EY, Beato QI, Ghosh S, Barthold JE, Bilyeu J, Emery NC, Pierce DM, Neu CP. Dynamic biophysical responses of neuronal cell nuclei and cytoskeletal structure following high impulse loading. Acta Biomater 2023; 163:339-350. [PMID: 35811070 PMCID: PMC10019187 DOI: 10.1016/j.actbio.2022.07.002] [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: 12/15/2021] [Revised: 06/11/2022] [Accepted: 07/01/2022] [Indexed: 12/28/2022]
Abstract
Cells are continuously exposed to dynamic environmental cues that influence their behavior. Mechanical cues can influence cellular and genomic architecture, gene expression, and intranuclear mechanics, providing evidence of mechanosensing by the nucleus, and a mechanoreciprocity between the nucleus and environment. Force disruption at the tissue level through aging, disease, or trauma, propagates to the nucleus and can have lasting consequences on proper functioning of the cell and nucleus. While the influence of mechanical cues leading to axonal damage has been well studied in neuronal cells, the mechanics of the nucleus following high impulse loading is still largely unexplored. Using an in vitro model of traumatic neural injury, we show a dynamic nuclear behavioral response to impulse stretch (up to 170% strain per second) through quantitative measures of nuclear movement, including tracking of rotation and internal motion. Differences in nuclear movement were observed between low and high strain magnitudes. Increased exposure to impulse stretch exaggerated the decrease in internal motion, assessed by particle tracking microrheology, and intranuclear displacements, assessed through high-resolution deformable image registration. An increase in F-actin puncta surrounding nuclei exposed to impulse stretch additionally demonstrated a corresponding disruption of the cytoskeletal network. Our results show direct biophysical nuclear responsiveness in neuronal cells through force propagation from the substrate to the nucleus. Understanding how mechanical forces perturb the morphological and behavioral response can lead to a greater understanding of how mechanical strain drives changes within the cell and nucleus, and may inform fundamental nuclear behavior after traumatic axonal injury. STATEMENT OF SIGNIFICANCE: The nucleus of the cell has been implicated as a mechano-sensitive organelle, courting molecular sensors and transmitting physical cues in order to maintain cellular and tissue homeostasis. Disruption of this network due to disease or high velocity forces (e.g., trauma) can not only result in orchestrated biochemical cascades, but also biophysical perturbations. Using an in vitro model of traumatic neural injury, we aimed to provide insight into the neuronal nuclear mechanics and biophysical responses at a continuum of strain magnitudes and after repetitive loads. Our image-based methods demonstrate mechanically-induced changes in cellular and nuclear behavior after high intensity loading and have the potential to further define mechanical thresholds of neuronal cell injury.
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Affiliation(s)
- Stephanie E Schneider
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Adrienne K Scott
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Benjamin Seelbinder
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Courtney Van Den Elzen
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Robert L Wilson
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Emily Y Miller
- Biomedical Engineering Program, University of Colorado Boulder, Boulder, CO, USA
| | - Quinn I Beato
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Soham Ghosh
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA; Department of Mechanical Engineering, Colorado State University, Fort Collins, CO, USA; School of Biomedical Engineering, Colorado State University, Fort Collins, CO, USA
| | - Jeanne E Barthold
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Jason Bilyeu
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA
| | - Nancy C Emery
- Department of Ecology and Evolutionary Biology, University of Colorado Boulder, Boulder, CO, USA
| | - David M Pierce
- Department of Mechanical Engineering, University of Connecticut, Storrs, CT, USA; Department of Biomedical Engineering, University of Connecticut, Storrs, CT, USA
| | - Corey P Neu
- Paul M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, CO, USA; Biomedical Engineering Program, University of Colorado Boulder, Boulder, CO, USA; BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.
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7
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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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8
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Eskandari F, Shafieian M, Aghdam MM, Laksari K. Morphological changes in glial cells arrangement under mechanical loading: A quantitative study. Injury 2022; 53:3617-3623. [PMID: 36089556 DOI: 10.1016/j.injury.2022.08.062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 08/26/2022] [Indexed: 02/02/2023]
Abstract
The mechanical properties and microstructure of brain tissue, as its two main physical parameters, could be affected by mechanical stimuli. In previous studies, microstructural alterations due to mechanical loading have received less attention than the mechanical properties of the tissue. Therefore, the current study aimed to investigate the effect of ex-vivo mechanical forces on the micro-architecture of brain tissue including axons and glial cells. A three-step loading protocol (i.e., loading-recovery-loading) including eight strain levels from 5% to 40% was applied to bovine brain samples with axons aligned in one preferred direction (each sample experienced only one level of strain). After either the first or secondary loading step, the samples were fixed, cut in planes parallel and perpendicular to the loading direction, and stained for histology. The histological images were analyzed to measure the end-to-end length of axons and glial cell-cell distances. The results showed that after both loading steps, as the strain increased, the changes in the cell nuclei arrangement in the direction parallel to axons were more significant compared to the other two perpendicular directions. Based on this evidence, we hypothesized that the spatial pattern of glial cells is highly affected by the orientation of axonal fibers. Moreover, the results revealed that in both loading steps, the maximum cell-cell distance occurred at 15% strain, and this distance decreased for higher strains. Since 15% strain is close to the previously reported brain injury threshold, this evidence could suggest that at higher strains, the axons start to rupture, causing a reduction in the displacement of glial cells. Accordingly, it was concluded that more attention to glial cells' architecture during mechanical loading may lead to introduce a new biomarker for brain injury.
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Affiliation(s)
- Faezeh Eskandari
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Mehdi Shafieian
- Department of Biomedical Engineering, Amirkabir University of Technology, Tehran, Iran.
| | - Mohammad M Aghdam
- Department of Mechanical Engineering, Amirkabir University of Technology, Tehran, Iran
| | - Kaveh Laksari
- Department of Biomedical Engineering, University of Arizona, Tucson, AZ, USA; Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ, USA
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9
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Shao X, Liu Z, Mao S, Han L. Unraveling the Mechanobiology Underlying Traumatic Brain Injury with Advanced Technologies and Biomaterials. Adv Healthc Mater 2022; 11:e2200760. [PMID: 35841392 DOI: 10.1002/adhm.202200760] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/27/2022] [Indexed: 01/27/2023]
Abstract
Traumatic brain injury (TBI) is a worldwide health and socioeconomic problem, associated with prolonged and complex neurological aftermaths, including a variety of functional deficits and neurodegenerative disorders. Research on the long-term effects has highlighted that TBI shall be regarded as a chronic health condition. The initiation and exacerbation of TBI involve a series of mechanical stimulations and perturbations, accompanied by mechanotransduction events within the brain tissues. Mechanobiology thus offers a unique perspective and likely promising approach to unravel the underlying molecular and biochemical mechanisms leading to neural cells dysfunction after TBI, which may contribute to the discovery of novel targets for future clinical treatment. This article investigates TBI and the subsequent brain dysfunction from a lens of neuromechanobiology. Following an introduction, the mechanobiological insights are examined into the molecular pathology of TBI, and then an overview is given of the latest research technologies to explore neuromechanobiology, with particular focus on microfluidics and biomaterials. Challenges and prospects in the current field are also discussed. Through this article, it is hoped that extensive technical innovation in biomedical devices and materials can be encouraged to advance the field of neuromechanobiology, paving potential ways for the research and rehabilitation of neurotrauma and neurological diseases.
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Affiliation(s)
- Xiaowei Shao
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China.,Suzhou Research Institute, Shandong University, Suzhou, Jiangsu, 215123, China
| | - Zhongqian Liu
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China
| | - Shijie Mao
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China
| | - Lin Han
- Institute of Marine Science and Technology, Shandong University, Qingdao, Shandong, 266237, China
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10
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Kalukula Y, Stephens AD, Lammerding J, Gabriele S. Mechanics and functional consequences of nuclear deformations. Nat Rev Mol Cell Biol 2022; 23:583-602. [PMID: 35513718 PMCID: PMC9902167 DOI: 10.1038/s41580-022-00480-z] [Citation(s) in RCA: 108] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2022] [Indexed: 02/08/2023]
Abstract
As the home of cellular genetic information, the nucleus has a critical role in determining cell fate and function in response to various signals and stimuli. In addition to biochemical inputs, the nucleus is constantly exposed to intrinsic and extrinsic mechanical forces that trigger dynamic changes in nuclear structure and morphology. Emerging data suggest that the physical deformation of the nucleus modulates many cellular and nuclear functions. These functions have long been considered to be downstream of cytoplasmic signalling pathways and dictated by gene expression. In this Review, we discuss an emerging perspective on the mechanoregulation of the nucleus that considers the physical connections from chromatin to nuclear lamina and cytoskeletal filaments as a single mechanical unit. We describe key mechanisms of nuclear deformations in time and space and provide a critical review of the structural and functional adaptive responses of the nucleus to deformations. We then consider the contribution of nuclear deformations to the regulation of important cellular functions, including muscle contraction, cell migration and human disease pathogenesis. Collectively, these emerging insights shed new light on the dynamics of nuclear deformations and their roles in cellular mechanobiology.
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Affiliation(s)
- Yohalie Kalukula
- University of Mons, Soft Matter and Biomaterials group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, CIRMAP, Place du Parc, 20 B-7000 Mons, Belgium
| | - Andrew D. Stephens
- Biology Department, University of Massachusetts Amherst, Amherst, MA, USA
| | - Jan Lammerding
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA,Nancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, NY 14853, USA
| | - Sylvain Gabriele
- University of Mons, Soft Matter and Biomaterials group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, CIRMAP, Place du Parc, 20 B-7000 Mons, Belgium
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11
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Mao Y, Nielsen P, Ali J. Passive and Active Microrheology for Biomedical Systems. Front Bioeng Biotechnol 2022; 10:916354. [PMID: 35866030 PMCID: PMC9294381 DOI: 10.3389/fbioe.2022.916354] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 06/08/2022] [Indexed: 12/12/2022] Open
Abstract
Microrheology encompasses a range of methods to measure the mechanical properties of soft materials. By characterizing the motion of embedded microscopic particles, microrheology extends the probing length scale and frequency range of conventional bulk rheology. Microrheology can be characterized into either passive or active methods based on the driving force exerted on probe particles. Tracer particles are driven by thermal energy in passive methods, applying minimal deformation to the assessed medium. In active techniques, particles are manipulated by an external force, most commonly produced through optical and magnetic fields. Small-scale rheology holds significant advantages over conventional bulk rheology, such as eliminating the need for large sample sizes, the ability to probe fragile materials non-destructively, and a wider probing frequency range. More importantly, some microrheological techniques can obtain spatiotemporal information of local microenvironments and accurately describe the heterogeneity of structurally complex fluids. Recently, there has been significant growth in using these minimally invasive techniques to investigate a wide range of biomedical systems both in vitro and in vivo. Here, we review the latest applications and advancements of microrheology in mammalian cells, tissues, and biofluids and discuss the current challenges and potential future advances on the horizon.
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Affiliation(s)
- Yating Mao
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Paige Nielsen
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Jamel Ali
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, United States
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
- *Correspondence: Jamel Ali,
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12
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Stability Analysis for a Fractional-Order Coupled FitzHugh–Nagumo-Type Neuronal Model. FRACTAL AND FRACTIONAL 2022. [DOI: 10.3390/fractalfract6050257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
The aim of this work is to describe the dynamics of a fractional-order coupled FitzHugh–Nagumo neuronal model. The equilibrium states are analyzed in terms of their stability properties, both dependently and independently of the fractional orders of the Caputo derivatives, based on recently established theoretical results. Numerical simulations are shown to clarify and exemplify the theoretical results.
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13
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Procès A, Luciano M, Kalukula Y, Ris L, Gabriele S. Multiscale Mechanobiology in Brain Physiology and Diseases. Front Cell Dev Biol 2022; 10:823857. [PMID: 35419366 PMCID: PMC8996382 DOI: 10.3389/fcell.2022.823857] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 03/08/2022] [Indexed: 12/11/2022] Open
Abstract
Increasing evidence suggests that mechanics play a critical role in regulating brain function at different scales. Downstream integration of mechanical inputs into biochemical signals and genomic pathways causes observable and measurable effects on brain cell fate and can also lead to important pathological consequences. Despite recent advances, the mechanical forces that influence neuronal processes remain largely unexplored, and how endogenous mechanical forces are detected and transduced by brain cells into biochemical and genetic programs have received less attention. In this review, we described the composition of brain tissues and their pronounced microstructural heterogeneity. We discuss the individual role of neuronal and glial cell mechanics in brain homeostasis and diseases. We highlight how changes in the composition and mechanical properties of the extracellular matrix can modulate brain cell functions and describe key mechanisms of the mechanosensing process. We then consider the contribution of mechanobiology in the emergence of brain diseases by providing a critical review on traumatic brain injury, neurodegenerative diseases, and neuroblastoma. We show that a better understanding of the mechanobiology of brain tissues will require to manipulate the physico-chemical parameters of the cell microenvironment, and to develop three-dimensional models that can recapitulate the complexity and spatial diversity of brain tissues in a reproducible and predictable manner. Collectively, these emerging insights shed new light on the importance of mechanobiology and its implication in brain and nerve diseases.
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Affiliation(s)
- Anthony Procès
- Mechanobiology and Biomaterials group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium.,Neurosciences Department, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Marine Luciano
- Mechanobiology and Biomaterials group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Yohalie Kalukula
- Mechanobiology and Biomaterials group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Laurence Ris
- Neurosciences Department, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Sylvain Gabriele
- Mechanobiology and Biomaterials group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
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14
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Sainio MT, Rasila T, Molchanova SM, Järvilehto J, Torregrosa-Muñumer R, Harjuhaahto S, Pennonen J, Huber N, Herukka SK, Haapasalo A, Zetterberg H, Taira T, Palmio J, Ylikallio E, Tyynismaa H. Neurofilament Light Regulates Axon Caliber, Synaptic Activity, and Organelle Trafficking in Cultured Human Motor Neurons. Front Cell Dev Biol 2022; 9:820105. [PMID: 35237613 PMCID: PMC8883324 DOI: 10.3389/fcell.2021.820105] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 12/28/2021] [Indexed: 11/27/2022] Open
Abstract
Neurofilament light (NFL) is one of the proteins forming multimeric neuron-specific intermediate filaments, neurofilaments, which fill the axonal cytoplasm, establish caliber growth, and provide structural support. Dominant missense mutations and recessive nonsense mutations in the neurofilament light gene (NEFL) are among the causes of Charcot–Marie–Tooth (CMT) neuropathy, which affects the peripheral nerves with the longest axons. We previously demonstrated that a neuropathy-causing homozygous nonsense mutation in NEFL led to the absence of NFL in patient-specific neurons. To understand the disease-causing mechanisms, we investigate here the functional effects of NFL loss in human motor neurons differentiated from induced pluripotent stem cells (iPSC). We used genome editing to generate NEFL knockouts and compared them to patient-specific nonsense mutants and isogenic controls. iPSC lacking NFL differentiated efficiently into motor neurons with normal axon growth and regrowth after mechanical axotomy and contained neurofilaments. Electrophysiological analysis revealed that motor neurons without NFL fired spontaneous and evoked action potentials with similar characteristics as controls. However, we found that, in the absence of NFL, human motor neurons 1) had reduced axonal caliber, 2) the amplitude of miniature excitatory postsynaptic currents (mEPSC) was decreased, 3) neurofilament heavy (NFH) levels were reduced and no compensatory increases in other filament subunits were observed, and 4) the movement of mitochondria and to a lesser extent lysosomes was increased. Our findings elaborate the functional roles of NFL in human motor neurons. NFL is not only a structural protein forming neurofilaments and filling the axonal cytoplasm, but our study supports the role of NFL in the regulation of synaptic transmission and organelle trafficking. To rescue the NFL deficiency in the patient-specific nonsense mutant motor neurons, we used three drugs, amlexanox, ataluren (PTC-124), and gentamicin to induce translational read-through or inhibit nonsense-mediated decay. However, the drugs failed to increase the amount of NFL protein to detectable levels and were toxic to iPSC-derived motor neurons.
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Affiliation(s)
- Markus T Sainio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Tiina Rasila
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Svetlana M Molchanova
- Molecular and Integrative Biosciences Research Program, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Julius Järvilehto
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Rubén Torregrosa-Muñumer
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Sandra Harjuhaahto
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Jana Pennonen
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland
| | - Nadine Huber
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Sanna-Kaisa Herukka
- Department of Neurology, Kuopio University Hospital, Kuopio, Finland.,Neurology, Institute of Clinical Medicine, University of Eastern Finland, Kuopio, Finland
| | - Annakaisa Haapasalo
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Henrik Zetterberg
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, Mölndal, Sweden.,Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at the University of Gothenburg, Mölndal, Sweden.,Department of Neurodegenerative Disease, UCL Institute of Neurology, London, United Kingdom.,UK Dementia Research Institute at UCL, London, United Kingdom.,Hong Kong Center for Neurodegenerative Diseases, Hong Kong, Hong Kong SAR, China
| | - Tomi Taira
- Department of Veterinary Biosciences, Faculty of Veterinary Medicine, Department of Veterinary Biosciences for Electrophysiology, University of Helsinki, Helsinki, Finland.,Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Johanna Palmio
- Neuromuscular Research Center, Tampere University Hospital and Tampere University, Tampere, Finland
| | - Emil Ylikallio
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Clinical Neurosciences, Neurology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
| | - Henna Tyynismaa
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Neuroscience Center, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.,Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
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15
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Magnetically-actuated microposts stimulate axon growth. Biophys J 2022; 121:374-382. [PMID: 34979131 PMCID: PMC8822606 DOI: 10.1016/j.bpj.2021.12.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Revised: 07/10/2021] [Accepted: 12/28/2021] [Indexed: 02/03/2023] Open
Abstract
New strategies to promote neuronal regeneration should aim to increase the speed of axonal elongation. Biochemical signaling is a key factor in axon growth, but recent discoveries have shown that mechanical force, through a process referred to as stretch growth, can significantly influence the elongation rate. Here, we develop a method to apply forces to primary hippocampal neurons from mice using magnetic microposts that actuate in response to an external magnetic field. Neurons are cultured onto these microposts and subjected to an average displacement of 0.2 μm at a frequency of 5 Hz. We find that the mechanical stimulation promotes an increase in the length of the axons compared to control conditions. In addition, there is an increase in the density of microtubules and in the amount of cisternae of the endoplasmic reticulum, providing evidence that stretch growth is accompanied by a mass addition to the neurite. Together, these results indicate that magnetically-actuated microposts can accelerate the rate of axon growth, paving the way for future applications in neuronal regeneration. VIDEO ABSTRACT.
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16
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Lantoine J, Procès A, Villers A, Halliez S, Buée L, Ris L, Gabriele S. Inflammatory Molecules Released by Mechanically Injured Astrocytes Trigger Presynaptic Loss in Cortical Neuronal Networks. ACS Chem Neurosci 2021; 12:3885-3897. [PMID: 34614352 DOI: 10.1021/acschemneuro.1c00488] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Deformation, compression, or stretching of brain tissues cause diffuse axonal injury (DAI) and induce structural and functional alterations of astrocytes, the most abundant cell type in the brain. To gain further insight into the role of mechanically activated astrocytes on neuronal networks, this study was designed to investigate whether cytokines released by mechanically activated astrocytes can affect the growth and synaptic connections of cortical neuronal networks. Astrocytes were cultivated on elastic membranes and subjected to repetitive mechanical insults, whereas well-defined protein micropatterns were used to form standardized neuronal networks. GFAP staining showed that astrocytes were mechanically activated after two cycles of stretch and mesoscale discovery assays indicated that injured astrocytes released four major cytokines. To understand the role of these cytokines, neuronal networks were cultured with the supernatant of healthy or mechanically activated astrocytes, and the individual contribution of the proinflammatory cytokine tumor necrosis factor-α (TNF-α) was studied. We found that the supernatant of two-cycle stretched astrocytes decreased presynaptic terminals and indicated that TNF-α must be considered a key player of the synaptic loss. Furthermore, our results indicate that cytokines released by injured astrocytes significantly modulate the balance between TNFR1 and TNFR2 receptors by enhancing R2 receptors. We demonstrated that TNF-α is not involved in this process, suggesting a predominant role of other secreted cytokines. Together, these results contribute to a better understanding of the consequences of repetitive astrocyte deformations and highlight the role of inflammatory signaling pathways in synaptic plasticity and modulation of TNFR1 and TNFR2 receptors.
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Affiliation(s)
- Joséphine Lantoine
- Mechanobiology & Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium
| | - Anthony Procès
- Mechanobiology & Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium
- Laboratory of Neuroscience, Research Institute for Biosciences, Faculty of Medicine and Pharmacy, University of Mons, 7000 Mons, Belgium
| | - Agnès Villers
- Laboratory of Neuroscience, Research Institute for Biosciences, Faculty of Medicine and Pharmacy, University of Mons, 7000 Mons, Belgium
| | - Sophie Halliez
- Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, LabEx DISTALZ, F-59000 Lille, France
| | - Luc Buée
- Univ. Lille, Inserm, CHU Lille, U1172 - LilNCog - Lille Neuroscience & Cognition, LabEx DISTALZ, F-59000 Lille, France
| | - Laurence Ris
- Laboratory of Neuroscience, Research Institute for Biosciences, Faculty of Medicine and Pharmacy, University of Mons, 7000 Mons, Belgium
| | - Sylvain Gabriele
- Mechanobiology & Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, 7000 Mons, Belgium
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17
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Braun NJ, Liao D, Alford PW. Orientation of neurites influences severity of mechanically induced tau pathology. Biophys J 2021; 120:3272-3282. [PMID: 34293301 PMCID: PMC8392125 DOI: 10.1016/j.bpj.2021.07.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 06/11/2021] [Accepted: 07/13/2021] [Indexed: 01/03/2023] Open
Abstract
Chronic traumatic encephalopathy is a neurodegenerative disease associated with repeated traumatic brain injury (TBI). Chronic traumatic encephalopathy is a tauopathy, in which cognitive decline is accompanied by the accumulation of neurofibrillary tangles of the protein tau in patients' brains. We recently found that mechanical force alone can induce tau mislocalization to dendritic spines and loss of synaptic function in in vitro neuronal cultures with random cell organization. However, in the brain, neurons are highly aligned, so here we aimed to determine how neuronal organization influences early-stage tauopathy caused by mechanical injury. Using microfabricated cell culture constructs to control the growth of neurites and an in vitro simulated TBI device to apply controlled mechanical deformation, we found that neuronal orientation with respect to the direction of a uniaxial high-strain-rate stretch injury influences the degree of tau pathology in injured neurons. We found that a mechanical stretch applied parallel to the neurite alignment induces greater mislocalization of tau proteins to dendritic spines than does a stretch with the same strain applied perpendicular to the neurites. Synaptic function, characterized by the amplitude of miniature excitatory postsynaptic currents, was similarly decreased in neurons with neurites aligned parallel to stretch, whereas in neurons aligned perpendicular to stretch, it had little to no functional loss. Experimental injury parameters (strain, strain rate, direction of stretch) were combined with a standard viscoelastic solid model to show that in our in vitro model, neurite work density during stretch correlates with tau mislocalization. These findings suggest that in a TBI, the magnitude of brain deformation is not wholly predictive of neurodegenerative consequences of TBI but that deformation relative to local neuronal architecture and the neurite mechanical energy during injury are better metrics for predicting trauma-induced tauopathy.
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Affiliation(s)
| | - Dezhi Liao
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota.
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18
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Shao X, Sørensen MH, Fang C, Chang RCC, Chu Z, Lin Y. Maturation of Neural Cells Leads to Enhanced Axon-Extracellular Matrix Adhesion and Altered Injury Response. Front Bioeng Biotechnol 2021; 8:621777. [PMID: 33490057 PMCID: PMC7815929 DOI: 10.3389/fbioe.2020.621777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/08/2020] [Indexed: 11/20/2022] Open
Abstract
Although it is known that stronger cell-extracellular matrix interactions will be developed as neurons mature, how such change influences their response against traumatic injury remains largely unknown. In this report, by transecting axons with a sharp atomic force microscope tip, we showed that the injury-induced retracting motion of axon can be temporarily arrested by tight NCAM (neural cell adhesion molecule) mediated adhesion patches, leading to a retraction curve decorated with sudden bursts. Interestingly, although the size of adhesion clusters (~0.5–1 μm) was found to be more or less the same in mature and immature neurons (after 7- and 3-days of culturing, respectively), the areal density of such clusters is three times higher in mature axons resulting in a much reduced retraction in response to injury. A physical model was also adopted to explain the observed retraction trajectories which suggested that apparent adhesion energy between axon and the substrate increases from ~0.12 to 0.39 mJ/m2 as neural cell matures, in good agreement with our experiments.
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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, China.,Department of Electrical and Electronic Engineering, Joint Appointment With School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Maja Højvang Sørensen
- Laboratory of Neurodegenerative Diseases, Li Ka Shing (LKS) Faculty of Medicine, School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Chao Fang
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.,HKU-Shenzhen Institute of Research and Innovation, Shenzhen, China
| | - Raymond Chuen Chung Chang
- Laboratory of Neurodegenerative Diseases, Li Ka Shing (LKS) Faculty of Medicine, School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Zhiqin Chu
- Department of Electrical and Electronic Engineering, Joint Appointment With School of Biomedical Sciences, The University of Hong Kong, Hong Kong, China
| | - Yuan Lin
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.,HKU-Shenzhen Institute of Research and Innovation, Shenzhen, China
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19
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Keating CE, Cullen DK. Mechanosensation in traumatic brain injury. Neurobiol Dis 2020; 148:105210. [PMID: 33259894 DOI: 10.1016/j.nbd.2020.105210] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/10/2020] [Accepted: 11/24/2020] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) is distinct from other neurological disorders because it is induced by a discrete event that applies extreme mechanical forces to the brain. This review describes how the brain senses, integrates, and responds to forces under both normal conditions and during injury. The response to forces is influenced by the unique mechanical properties of brain tissue, which differ by region, cell type, and sub-cellular structure. Elements such as the extracellular matrix, plasma membrane, transmembrane receptors, and cytoskeleton influence its properties. These same components also act as force-sensors, allowing neurons and glia to respond to their physical environment and maintain homeostasis. However, when applied forces become too large, as in TBI, these components may respond in an aberrant manner or structurally fail, resulting in unique pathological sequelae. This so-called "pathological mechanosensation" represents a spectrum of cellular responses, which vary depending on the overall biomechanical parameters of the injury and may be compounded by repetitive injuries. Such aberrant physical responses and/or damage to cells along with the resulting secondary injury cascades can ultimately lead to long-term cellular dysfunction and degeneration, often resulting in persistent deficits. Indeed, pathological mechanosensation not only directly initiates secondary injury cascades, but this post-physical damage environment provides the context in which these cascades unfold. Collectively, these points underscore the need to use experimental models that accurately replicate the biomechanics of TBI in humans. Understanding cellular responses in context with injury biomechanics may uncover therapeutic targets addressing various facets of trauma-specific sequelae.
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Affiliation(s)
- Carolyn E Keating
- Department of Neurosurgery, Center for Brain Injury and Repair, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz VA Medical Center, USA
| | - D Kacy Cullen
- Department of Neurosurgery, Center for Brain Injury and Repair, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, USA; Center for Neurotrauma, Neurodegeneration, and Restoration, Corporal Michael J. Crescenz VA Medical Center, USA.
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20
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Braun NJ, Yao KR, Alford PW, Liao D. Mechanical injuries of neurons induce tau mislocalization to dendritic spines and tau-dependent synaptic dysfunction. Proc Natl Acad Sci U S A 2020; 117:29069-29079. [PMID: 33139536 PMCID: PMC7682580 DOI: 10.1073/pnas.2008306117] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Chronic traumatic encephalopathy (CTE) is associated with repeated traumatic brain injuries (TBI) and is characterized by cognitive decline and the presence of neurofibrillary tangles (NFTs) of the protein tau in patients' brains. Here we provide direct evidence that cell-scale mechanical deformation can elicit tau abnormalities and synaptic deficits in neurons. Using computational modeling, we find that the early pathological loci of NFTs in CTE brains are regions of high deformation during injury. The mechanical energy associated with high-strain rate deformation alone can induce tau mislocalization to dendritic spines and synaptic deficits in cultured rat hippocampal neurons. These cellular changes are mediated by tau hyperphosphorylation and can be reversed through inhibition of GSK3β and CDK5 or genetic deletion of tau. Together, these findings identify a mechanistic pathway that directly relates mechanical deformation of neurons to tau-mediated synaptic impairments and provide a possibly exploitable therapeutic pathway to combat CTE.
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Affiliation(s)
- Nicholas J Braun
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455
| | - Katherine R Yao
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455;
| | - Dezhi Liao
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455
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21
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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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22
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Jung W, Li J, Chaudhuri O, Kim T. Nonlinear Elastic and Inelastic Properties of Cells. J Biomech Eng 2020; 142:100806. [PMID: 32253428 PMCID: PMC7477719 DOI: 10.1115/1.4046863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 03/27/2020] [Indexed: 12/15/2022]
Abstract
Mechanical forces play an important role in various physiological processes, such as morphogenesis, cytokinesis, and migration. Thus, in order to illuminate mechanisms underlying these physiological processes, it is crucial to understand how cells deform and respond to external mechanical stimuli. During recent decades, the mechanical properties of cells have been studied extensively using diverse measurement techniques. A number of experimental studies have shown that cells are far from linear elastic materials. Cells exhibit a wide variety of nonlinear elastic and inelastic properties. Such complicated properties of cells are known to emerge from unique mechanical characteristics of cellular components. In this review, we introduce major cellular components that largely govern cell mechanical properties and provide brief explanations of several experimental techniques used for rheological measurements of cell mechanics. Then, we discuss the representative nonlinear elastic and inelastic properties of cells. Finally, continuum and discrete computational models of cell mechanics, which model both nonlinear elastic and inelastic properties of cells, will be described.
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Affiliation(s)
- Wonyeong Jung
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907
| | - Jing Li
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907
| | - Ovijit Chaudhuri
- Department of Mechanical Engineering, Stanford University, 440 Escondido Mall, Stanford, CA 94305
| | - Taeyoon Kim
- Weldon School of Biomedical Engineering, Purdue University, 206 S. Martin Jischke Drive, West Lafayette, IN 47907
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23
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Aermes C, Hayn A, Fischer T, Mierke CT. Environmentally controlled magnetic nano-tweezer for living cells and extracellular matrices. Sci Rep 2020; 10:13453. [PMID: 32778758 PMCID: PMC7417586 DOI: 10.1038/s41598-020-70428-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 07/16/2020] [Indexed: 01/08/2023] Open
Abstract
The magnetic tweezer technique has become a versatile tool for unfolding or folding of individual molecules, mainly DNA. In addition to single molecule analysis, the magnetic tweezer can be used to analyze the mechanical properties of cells and extracellular matrices. We have established a magnetic tweezer that is capable of measuring the linear and non-linear viscoelastic behavior of a wide range of soft matter in precisely controlled environmental conditions, such as temperature, CO2 and humidity. The magnetic tweezer presented in this study is suitable to detect specific differences in the mechanical properties of different cell lines, such as human breast cancer cells and mouse embryonic fibroblasts, as well as collagen matrices of distinct concentrations in the presence and absence of fibronectin crosslinks. The precise calibration and control mechanism employed in the presented magnetic tweezer setup provides the ability to apply physiological force up to 5 nN on 4.5 µm superparamagnetic beads coated with fibronectin and coupled to the cells or collagen matrices. These measurements reveal specific local linear and non-linear viscoelastic behavior of the investigated samples. The viscoelastic response of cells and collagen matrices to the force application is best described by a weak power law behavior. Our results demonstrate that the stress stiffening response and the fluidization of cells is cell type specific and varies largely between differently invasive and aggressive cancer cells. Finally, we showed that the viscoelastic behavior of collagen matrices with and without fibronectin crosslinks measured by the magnetic tweezer can be related to the microstructure of these matrices.
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Affiliation(s)
- Christian Aermes
- Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
| | - Alexander Hayn
- Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
| | - Tony Fischer
- Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany
| | - Claudia Tanja Mierke
- Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, University of Leipzig, Linnéstr. 5, 04103, Leipzig, Germany.
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24
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Espinosa-Hoyos D, Burstein SR, Cha J, Jain T, Nijsure M, Jagielska A, Fossati V, Van Vliet KJ. Mechanosensitivity of Human Oligodendrocytes. Front Cell Neurosci 2020; 14:222. [PMID: 32848617 PMCID: PMC7420028 DOI: 10.3389/fncel.2020.00222] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 06/22/2020] [Indexed: 12/28/2022] Open
Abstract
Oligodendrocytes produce and repair myelin, which is critical for the integrity and function of the central nervous system (CNS). Oligodendrocyte and oligodendrocyte progenitor cell (OPC) biology is modulated in vitro by mechanical cues within the magnitudes observed in vivo. In some cases, these cues are sufficient to accelerate or inhibit terminal differentiation of murine oligodendrocyte progenitors. However, our understanding of oligodendrocyte lineage mechanobiology has been restricted primarily to animal models to date, due to the inaccessibility and challenges of human oligodendrocyte cell culture. Here, we probe the mechanosensitivity of human oligodendrocyte lineage cells derived from human induced pluripotent stem cells. We target phenotypically distinct stages of the human oligodendrocyte lineage and quantify the effect of substratum stiffness on cell migration and differentiation, within the range documented in vivo. We find that human oligodendrocyte lineage cells exhibit mechanosensitive migration and differentiation. Further, we identify two patterns of human donor line-dependent mechanosensitive differentiation. Our findings illustrate the variation among human oligodendrocyte responses, otherwise not captured by animal models, that are important for translational research. Moreover, these findings highlight the importance of studying glia under conditions that better approximate in vivo mechanical cues. Despite significant progress in human oligodendrocyte derivation methodology, the extended duration, low yield, and low selectivity of human-induced pluripotent stem cell-derived oligodendrocyte protocols significantly limit the scale-up and implementation of these cells and protocols for in vivo and in vitro applications. We propose that mechanical modulation, in combination with traditional soluble and insoluble factors, provides a key avenue to address these challenges in cell production and in vitro analysis.
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Affiliation(s)
- Daniela Espinosa-Hoyos
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Suzanne R. Burstein
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - Jaaram Cha
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Tanya Jain
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - Madhura Nijsure
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - Anna Jagielska
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
- Critical Analytics for Manufacturing Personalized-Medicine (CAMP) Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology (SMART) CREATE, Singapore, Singapore
| | - Valentina Fossati
- The New York Stem Cell Foundation Research Institute, New York, NY, United States
| | - Krystyn J. Van Vliet
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
- Critical Analytics for Manufacturing Personalized-Medicine (CAMP) Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology (SMART) CREATE, Singapore, Singapore
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, United States
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25
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Iendaltseva O, Orlova VV, Mummery CL, Danen EHJ, Schmidt T. Fibronectin Patches as Anchoring Points for Force Sensing and Transmission in Human Induced Pluripotent Stem Cell-Derived Pericytes. Stem Cell Reports 2020; 14:1107-1122. [PMID: 32470326 PMCID: PMC7355144 DOI: 10.1016/j.stemcr.2020.05.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 04/30/2020] [Accepted: 05/01/2020] [Indexed: 12/24/2022] Open
Abstract
Pericytes (PCs) have been reported to contribute to the mechanoregulation of the capillary diameter and blood flow in health and disease. How this is realized remains poorly understood. We designed several models representing basement membrane (BM) in between PCs and endothelial cells (ECs). These models captured a unique protein organization with micron-sized FN patches surrounded by laminin (LM) and allowed to obtain quantitative information on PC morphology and contractility. Using human induced pluripotent stem cell-derived PCs, we could address mechanical aspects of mid-capillary PC behavior in vitro. Our results showed that PCs strongly prefer FN patches over LM for adhesion formation, have an optimal stiffness for spreading in the range of EC rigidity, and react in a non-canonical way with increased traction forces and reduced spreading on other stiffness then the optimal. Our approach opens possibilities to further study PC force regulation under well-controlled conditions.
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Affiliation(s)
- Olga Iendaltseva
- Physics of Life Processes, Leiden Institute of Physics, Leiden University, Einsteinweg 55, Leiden, South Holland 2333 CC, the Netherlands; Division of Drug Discovery and Safety, Leiden Academic Center for Drug Research, Leiden University, Einsteinweg 55, Leiden, South Holland 2333 CC, the Netherlands
| | - Valeria V Orlova
- Department of Anatomy and Embryology, Leiden University Medical Center (LUMC), Leiden, South Holland, the Netherlands
| | - Christine L Mummery
- Department of Anatomy and Embryology, Leiden University Medical Center (LUMC), Leiden, South Holland, the Netherlands
| | - Erik H J Danen
- Division of Drug Discovery and Safety, Leiden Academic Center for Drug Research, Leiden University, Einsteinweg 55, Leiden, South Holland 2333 CC, the Netherlands.
| | - Thomas Schmidt
- Physics of Life Processes, Leiden Institute of Physics, Leiden University, Einsteinweg 55, Leiden, South Holland 2333 CC, the Netherlands.
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26
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Ling T, Boyle KC, Zuckerman V, Flores T, Ramakrishnan C, Deisseroth K, Palanker D. High-speed interferometric imaging reveals dynamics of neuronal deformation during the action potential. Proc Natl Acad Sci U S A 2020; 117:10278-10285. [PMID: 32341158 PMCID: PMC7229674 DOI: 10.1073/pnas.1920039117] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Neurons undergo nanometer-scale deformations during action potentials, and the underlying mechanism has been actively debated for decades. Previous observations were limited to a single spot or the cell boundary, while movement across the entire neuron during the action potential remained unclear. Here we report full-field imaging of cellular deformations accompanying the action potential in mammalian neuron somas (-1.8 to 1.4 nm) and neurites (-0.7 to 0.9 nm), using high-speed quantitative phase imaging with a temporal resolution of 0.1 ms and an optical path length sensitivity of <4 pm per pixel. The spike-triggered average, synchronized to electrical recording, demonstrates that the time course of the optical phase changes closely matches the dynamics of the electrical signal. Utilizing the spatial and temporal correlations of the phase signals across the cell, we enhance the detection and segmentation of spiking cells compared to the shot-noise-limited performance of single pixels. Using three-dimensional (3D) cellular morphology extracted via confocal microscopy, we demonstrate that the voltage-dependent changes in the membrane tension induced by ionic repulsion can explain the magnitude, time course, and spatial features of the phase imaging. Our full-field observations of the spike-induced deformations shed light upon the electromechanical coupling mechanism in electrogenic cells and open the door to noninvasive label-free imaging of neural signaling.
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Affiliation(s)
- Tong Ling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305;
- Department of Ophthalmology, Stanford University, Stanford, CA 94305
| | - Kevin C Boyle
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305;
| | - Valentina Zuckerman
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305
| | - Thomas Flores
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305
| | | | - Karl Deisseroth
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305;
- Department of Ophthalmology, Stanford University, Stanford, CA 94305
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27
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28
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Abalymov A, Van der Meeren L, Saveleva M, Prikhozhdenko E, Dewettinck K, Parakhonskiy B, Skirtach AG. Cells-Grab-on Particles: A Novel Approach to Control Cell Focal Adhesion on Hybrid Thermally Annealed Hydrogels. ACS Biomater Sci Eng 2020; 6:3933-3944. [DOI: 10.1021/acsbiomaterials.0c00119] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Anatolii Abalymov
- Department of Biotechnology, University of Ghent, Ghent 9000, Belgium
- Remote Controlled Theranostic Systems Lab, Educational Research Institute of Nanostructures and Biosystems, Saratov State University, Saratov 410012, Russia
| | | | - Mariia Saveleva
- Department of Biotechnology, University of Ghent, Ghent 9000, Belgium
- Remote Controlled Theranostic Systems Lab, Educational Research Institute of Nanostructures and Biosystems, Saratov State University, Saratov 410012, Russia
| | - Ekaterina Prikhozhdenko
- Faculty of Nano- and Biomedical Technologies, Saratov State University, Saratov 410012, Russia
| | - Koen Dewettinck
- Department of Food Technology, Safety & Health, University of Gent, Ghent 9000, Belgium
| | | | - Andre G. Skirtach
- Department of Biotechnology, University of Ghent, Ghent 9000, Belgium
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29
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Dubey S, Bhembre N, Bodas S, Veer S, Ghose A, Callan-Jones A, Pullarkat P. The axonal actin-spectrin lattice acts as a tension buffering shock absorber. eLife 2020; 9:51772. [PMID: 32267230 PMCID: PMC7190353 DOI: 10.7554/elife.51772] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 04/06/2020] [Indexed: 12/11/2022] Open
Abstract
Axons span extreme distances and are subject to significant stretch deformations during limb movements or sudden head movements, especially during impacts. Yet, axon biomechanics, and its relation to the ultrastructure that allows axons to withstand mechanical stress, is poorly understood. Using a custom developed force apparatus, we demonstrate that chick dorsal root ganglion axons exhibit a tension buffering or strain-softening response, where its steady state elastic modulus decreases with increasing strain. We then explore the contributions from the various cytoskeletal components of the axon to show that the recently discovered membrane-associated actin-spectrin scaffold plays a prominent mechanical role. Finally, using a theoretical model, we argue that the actin-spectrin skeleton acts as an axonal tension buffer by reversibly unfolding repeat domains of the spectrin tetramers to release excess mechanical stress. Our results revise the current viewpoint that microtubules and their associated proteins are the only significant load-bearing elements in axons.
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Affiliation(s)
| | | | - Shivani Bodas
- Indian Institute of Science Education and Research, Pune, India
| | - Sukh Veer
- Raman Research Institute, Bangalore, India
| | - Aurnab Ghose
- Indian Institute of Science Education and Research, Pune, India
| | - Andrew Callan-Jones
- Laboratory of Complex Materials Systems, Paris Diderot University, Paris, France
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30
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Song Y, Soto J, Chen B, Yang L, Li S. Cell engineering: Biophysical regulation of the nucleus. Biomaterials 2020; 234:119743. [PMID: 31962231 DOI: 10.1016/j.biomaterials.2019.119743] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 12/02/2019] [Accepted: 12/25/2019] [Indexed: 12/12/2022]
Abstract
Cells live in a complex and dynamic microenvironment, and a variety of microenvironmental cues can regulate cell behavior. In addition to biochemical signals, biophysical cues can induce not only immediate intracellular responses, but also long-term effects on phenotypic changes such as stem cell differentiation, immune cell activation and somatic cell reprogramming. Cells respond to mechanical stimuli via an outside-in and inside-out feedback loop, and the cell nucleus plays an important role in this process. The mechanical properties of the nucleus can directly or indirectly modulate mechanotransduction, and the physical coupling of the cell nucleus with the cytoskeleton can affect chromatin structure and regulate the epigenetic state, gene expression and cell function. In this review, we will highlight the recent progress in nuclear biomechanics and mechanobiology in the context of cell engineering, tissue remodeling and disease development.
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Affiliation(s)
- Yang Song
- Department of Bioengineering, University of California, Los Angeles, CA, USA; School of Bioengineering, Chongqing University, Chongqing, 400044, China
| | - Jennifer Soto
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Binru Chen
- Department of Bioengineering, University of California, Los Angeles, CA, USA
| | - Li Yang
- School of Bioengineering, Chongqing University, Chongqing, 400044, China
| | - Song Li
- Department of Bioengineering, University of California, Los Angeles, CA, USA; Department of Medicine, University of California, Los Angeles, CA, USA.
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31
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Makhija EP, Espinosa-Hoyos D, Jagielska A, Van Vliet KJ. Mechanical regulation of oligodendrocyte biology. Neurosci Lett 2019; 717:134673. [PMID: 31838017 DOI: 10.1016/j.neulet.2019.134673] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 11/25/2019] [Accepted: 12/01/2019] [Indexed: 12/27/2022]
Abstract
Oligodendrocytes (OL) are a subset of glial cells in the central nervous system (CNS) comprising the brain and spinal cord. The CNS environment is defined by complex biochemical and biophysical cues during development and response to injury or disease. In the last decade, significant progress has been made in understanding some of the key biophysical factors in the CNS that modulate OL biology, including their key role in myelination of neurons. Taken together, those studies offer translational implications for remyelination therapies, pharmacological research, identification of novel drug targets, and improvements in methods to generate human oligodendrocyte progenitor cells (OPCs) and OLs from donor stem cells in vitro. This review summarizes current knowledge of how various physical and mechanical cues affect OL biology and its implications for disease, therapeutic approaches, and generation of human OPCs and OLs.
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Affiliation(s)
- Ekta P Makhija
- BioSystems & Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research & Technology (SMART) CREATE, Singapore 138602; Critical Analytics for Manufacturing Personalized-Medicine (CAMP) Interdisciplinary Research Group, Singapore-MIT Alliance for Research & Technology (SMART) CREATE, 138602, Singapore
| | - Daniela Espinosa-Hoyos
- BioSystems & Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research & Technology (SMART) CREATE, Singapore 138602; Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA
| | - Anna Jagielska
- BioSystems & Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research & Technology (SMART) CREATE, Singapore 138602; Department of Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
| | - Krystyn J Van Vliet
- BioSystems & Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research & Technology (SMART) CREATE, Singapore 138602; Critical Analytics for Manufacturing Personalized-Medicine (CAMP) Interdisciplinary Research Group, Singapore-MIT Alliance for Research & Technology (SMART) CREATE, 138602, Singapore; Department of Materials Science & Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 USA.
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32
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Chighizola M, Dini T, Lenardi C, Milani P, Podestà A, Schulte C. Mechanotransduction in neuronal cell development and functioning. Biophys Rev 2019; 11:701-720. [PMID: 31617079 PMCID: PMC6815321 DOI: 10.1007/s12551-019-00587-2] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 08/29/2019] [Indexed: 12/21/2022] Open
Abstract
Although many details remain still elusive, it became increasingly evident in recent years that mechanosensing of microenvironmental biophysical cues and subsequent mechanotransduction are strongly involved in the regulation of neuronal cell development and functioning. This review gives an overview about the current understanding of brain and neuronal cell mechanobiology and how it impacts on neurogenesis, neuronal migration, differentiation, and maturation. We will focus particularly on the events in the cell/microenvironment interface and the decisive extracellular matrix (ECM) parameters (i.e. rigidity and nanometric spatial organisation of adhesion sites) that modulate integrin adhesion complex-based mechanosensing and mechanotransductive signalling. It will also be outlined how biomaterial approaches mimicking essential ECM features help to understand these processes and how they can be used to control and guide neuronal cell behaviour by providing appropriate biophysical cues. In addition, principal biophysical methods will be highlighted that have been crucial for the study of neuronal mechanobiology.
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Affiliation(s)
- Matteo Chighizola
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (C.I.Ma.I.Na.) and Department of Physics ``Aldo Pontremoli'', Università degli Studi di Milano, via Celoria 16, 20133, Milan, Italy
| | - Tania Dini
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (C.I.Ma.I.Na.) and Department of Physics ``Aldo Pontremoli'', Università degli Studi di Milano, via Celoria 16, 20133, Milan, Italy
| | - Cristina Lenardi
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (C.I.Ma.I.Na.) and Department of Physics ``Aldo Pontremoli'', Università degli Studi di Milano, via Celoria 16, 20133, Milan, Italy
| | - Paolo Milani
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (C.I.Ma.I.Na.) and Department of Physics ``Aldo Pontremoli'', Università degli Studi di Milano, via Celoria 16, 20133, Milan, Italy
| | - Alessandro Podestà
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (C.I.Ma.I.Na.) and Department of Physics ``Aldo Pontremoli'', Università degli Studi di Milano, via Celoria 16, 20133, Milan, Italy
| | - Carsten Schulte
- Interdisciplinary Centre for Nanostructured Materials and Interfaces (C.I.Ma.I.Na.) and Department of Physics ``Aldo Pontremoli'', Università degli Studi di Milano, via Celoria 16, 20133, Milan, Italy.
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33
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Dagro A, Rajbhandari L, Orrego S, Kang SH, Venkatesan A, Ramesh KT. Quantifying the Local Mechanical Properties of Cells in a Fibrous Three-Dimensional Microenvironment. Biophys J 2019; 117:817-828. [PMID: 31421835 DOI: 10.1016/j.bpj.2019.07.042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 06/28/2019] [Accepted: 07/26/2019] [Indexed: 12/27/2022] Open
Abstract
Measurements of the mechanical response of biological cells are critical for understanding injury and disease, for developing diagnostic tools, and for computational models in mechanobiology. Although it is well known that cells are sensitive to the topography of their microenvironment, the current paradigm in mechanical testing of adherent cells is mostly limited to specimens grown on flat two-dimensional substrates. In this study, we introduce a technique in which cellular indentation via optical trapping is performed on cells at a high spatial resolution to obtain their regional mechanical properties while they exist in a more favorable three-dimensional microenvironment. We combine our approach with nonlinear contact mechanics theory to consider the effects of a large deformation. This allows us to probe length scales that are relevant for obtaining overall cell stiffness values. The experimental results herein provide the hyperelastic material properties at both high (∼100 s-1) and low (∼1-10 s-1) strain rates of murine central nervous system glial cells. The limitations due to possible misalignment of the indenter in the three-dimensional space are examined using a computational model.
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Affiliation(s)
- Amy Dagro
- U.S. Army Research Laboratory, Aberdeen Proving Ground, Maryland.
| | | | - Santiago Orrego
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland
| | - Sung Hoon Kang
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland; Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, Maryland
| | - Arun Venkatesan
- Department of Neurology, Johns Hopkins University, Baltimore, Maryland
| | - Kaliat T Ramesh
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland; Hopkins Extreme Materials Institute, Johns Hopkins University, Baltimore, Maryland
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34
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Mohammed D, Versaevel M, Bruyère C, Alaimo L, Luciano M, Vercruysse E, Procès A, Gabriele S. Innovative Tools for Mechanobiology: Unraveling Outside-In and Inside-Out Mechanotransduction. Front Bioeng Biotechnol 2019; 7:162. [PMID: 31380357 PMCID: PMC6646473 DOI: 10.3389/fbioe.2019.00162] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/20/2019] [Indexed: 12/26/2022] Open
Abstract
Cells and tissues can sense and react to the modifications of the physico-chemical properties of the extracellular environment (ECM) through integrin-based adhesion sites and adapt their physiological response in a process called mechanotransduction. Due to their critical localization at the cell-ECM interface, transmembrane integrins are mediators of bidirectional signaling, playing a key role in “outside-in” and “inside-out” signal transduction. After presenting the basic conceptual fundamentals related to cell mechanobiology, we review the current state-of-the-art technologies that facilitate the understanding of mechanotransduction signaling pathways. Finally, we highlight innovative technological developments that can help to advance our understanding of the mechanisms underlying nuclear mechanotransduction.
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Affiliation(s)
- Danahe Mohammed
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Marie Versaevel
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Céline Bruyère
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Laura Alaimo
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Marine Luciano
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Eléonore Vercruysse
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Anthony Procès
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium.,Department of Neurosciences, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Sylvain Gabriele
- Mechanobiology and Soft Matter Group, Interfaces and Complex Fluids Laboratory, Research Institute for Biosciences, University of Mons, Mons, Belgium
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35
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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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36
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A mechanoelectrical coupling model of neurons under stretching. J Mech Behav Biomed Mater 2019; 93:213-221. [DOI: 10.1016/j.jmbbm.2019.02.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 02/04/2019] [Accepted: 02/04/2019] [Indexed: 12/20/2022]
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37
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Hlavac N, VandeVord PJ. Astrocyte Mechano-Activation by High-Rate Overpressure Involves Alterations in Structural and Junctional Proteins. Front Neurol 2019; 10:99. [PMID: 30853931 PMCID: PMC6395392 DOI: 10.3389/fneur.2019.00099] [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: 09/10/2018] [Accepted: 01/24/2019] [Indexed: 11/13/2022] Open
Abstract
Primary blast neurotrauma represents a unique injury paradigm characterized by high-rate overpressure effects on brain tissue. One major hallmark of blast neurotrauma is glial reactivity, notably prolonged astrocyte activation. This cellular response has been mainly defined in primary blast neurotrauma by increased intermediate filament expression. Because the intermediate filament networks physically interface with transmembrane proteins for junctional support, it was hypothesized that cell junction regulation is altered in the reactive phenotype as well. This would have implications for downstream transcriptional regulation via signal transduction pathways like nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). Therefore, a custom high-rate overpressure simulator was built for in vitro testing using mechanical conditions based on intracranial pressure measurements in a rat model of blast neurotrauma. Primary rat astrocytes were exposed to isolated high-rate mechanical stimulation to study cell junction dynamics in relation to their mechano-activation. First, a time course for "classical" features of reactivity was devised by evaluation of glial fibrillary acidic protein (GFAP) and proliferating cell nuclear antigen (PCNA) expression. This was followed by gene and protein expression for both gap junction (connexins) and anchoring junction proteins (integrins and cadherins). Signal transduction analysis was carried out by nuclear localization of two molecules, NF-κB p65 and mitogen-activated protein kinase (MAPK) p38. Results indicated significant increases in connexin-43 expression and PCNA first at 24 h post-overpressure (p < 0.05), followed by structural reactivity (via increased GFAP, p < 0.05) corresponding to increased anchoring junction dynamics at 48 h post-overpressure (p < 0.05). Moreover, increased phosphorylation of focal adhesion kinase (FAK) was observed in addition to increased nuclear localization of both p65 and p38 (p < 0.05) during the period of structural reactivity. To evaluate the transcriptional activity of p65 in the nucleus, electrophoretic mobility shift assay was conducted for a binding site on the promoter region for intracellular adhesion molecule-1 (ICAM-1), an antagonist of tight junctions. A significant increase in the interaction of nuclear proteins with the NF-κB site on the ICAM-1 corresponded to increased gene and protein expression of ICAM-1 (p < 0.05). Altogether, these results indicate multiple targets and corresponding signaling pathways which involve cell junction dynamics in the mechano-activation of astrocytes following high-rate overpressure.
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Affiliation(s)
- Nora Hlavac
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute, Blacksburg, VA, United States
| | - Pamela J VandeVord
- Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute, Blacksburg, VA, United States.,Department of Research, Salem Veterans Affairs Medical Center, Salem, VA, United States
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38
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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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39
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Micheva KD, Chang EF, Nana AL, Seeley WW, Ting JT, Cobbs C, Lein E, Smith SJ, Weinberg RJ, Madison DV. Distinctive Structural and Molecular Features of Myelinated Inhibitory Axons in Human Neocortex. eNeuro 2018; 5:ENEURO.0297-18.2018. [PMID: 30406183 PMCID: PMC6220577 DOI: 10.1523/eneuro.0297-18.2018] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 09/02/2018] [Accepted: 09/10/2018] [Indexed: 11/21/2022] Open
Abstract
Numerous types of inhibitory neurons sculpt the performance of human neocortical circuits, with each type exhibiting a constellation of subcellular phenotypic features in support of its specialized functions. Axonal myelination has been absent among the characteristics used to distinguish inhibitory neuron types; in fact, very little is known about myelinated inhibitory axons in human neocortex. Here, using array tomography to analyze samples of neurosurgically excised human neocortex, we show that inhibitory myelinated axons originate predominantly from parvalbumin-containing interneurons. Compared to myelinated excitatory axons, they have higher neurofilament and lower microtubule content, shorter nodes of Ranvier, and more myelin basic protein (MBP) in their myelin sheath. Furthermore, these inhibitory axons have more mitochondria, likely to sustain the high energy demands of parvalbumin interneurons, as well as more 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), a protein enriched in the myelin cytoplasmic channels that are thought to facilitate the delivery of nutrients from ensheathing oligodendrocytes. Our results demonstrate that myelinated axons of parvalbumin inhibitory interneurons exhibit distinctive features that may support the specialized functions of this neuron type in human neocortical circuits.
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Affiliation(s)
- Kristina D. Micheva
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305
| | - Edward F. Chang
- Department of Neurological Surgery, University of California San Francisco, San Francisco, CA, 94143
| | - Alissa L. Nana
- Memory and Aging Center, Department of Neurology, University of California San Francisco, San Francisco, CA, 94143
| | - William W. Seeley
- Memory and Aging Center, Department of Neurology, University of California San Francisco, San Francisco, CA, 94143
- Department of Pathology, University of California San Francisco, San Francisco, CA, 94143
| | - Jonathan T. Ting
- Cell Types Program, Allen Institute for Brain Science, Seattle, WA, 98109
| | - Charles Cobbs
- The Ben and Catherine Ivy Center for Advanced Brain Tumor Treatment, Swedish Neuroscience Institute, Seattle, WA, 98122
| | - Ed Lein
- Cell Types Program, Allen Institute for Brain Science, Seattle, WA, 98109
| | - Stephen J Smith
- Cell Types Program, Allen Institute for Brain Science, Seattle, WA, 98109
| | - Richard J. Weinberg
- Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599
| | - Daniel V. Madison
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, 94305
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40
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Regional variations in stiffness in live mouse brain tissue determined by depth-controlled indentation mapping. Sci Rep 2018; 8:12517. [PMID: 30131608 PMCID: PMC6104037 DOI: 10.1038/s41598-018-31035-y] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 08/10/2018] [Indexed: 11/08/2022] Open
Abstract
The mechanical properties of brain tissue play a pivotal role in neurodevelopment and neurological disorders. Yet, at present, there is no consensus on how the different structural parts of the tissue contribute to its stiffness variations. Here, we have gathered depth-controlled indentation viscoelasticity maps of the hippocampus of acute horizontal live mouse brain slices. Our results confirm the highly viscoelestic nature of brain tissue. We further show that the mechanical properties are non-uniform and at least related to differences in morphological composition. Interestingly, areas with higher nuclear density appear to be softer than areas with lower nuclear density.
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41
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Montanino A, Kleiven S. Utilizing a Structural Mechanics Approach to Assess the Primary Effects of Injury Loads Onto the Axon and Its Components. Front Neurol 2018; 9:643. [PMID: 30127763 PMCID: PMC6087765 DOI: 10.3389/fneur.2018.00643] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 07/17/2018] [Indexed: 12/03/2022] Open
Abstract
Diffuse axonal injury (DAI) occurs as a result of the transmission of rapid dynamic loads from the head to the brain and specifically to its neurons. Despite being one of the most common and most deleterious types of traumatic brain injury (TBI), the inherent cell injury mechanism is yet to be understood. Experimental observations have led to the formulation of different hypotheses, such as mechanoporation of the axolemma and microtubules (MTs) breakage. With the goal of singling out the mechanical aspect of DAI and to resolve the ambiguity behind its injury mechanism, a composite finite element (FE) model of a representative volume of an axon was developed. Once calibrated and validated against published experimental data, the axonal model was used to simulate injury scenarios. The resulting strain distributions along its components were then studied in dependence of strain rate and of typical modeling choices such as the applied MT constraints and tau proteins failure. Results show that oversimplifying the MT bundle kinematic entails a systematic attenuation (cf = 2.33) of the computed maximum MT strain. Nevertheless, altogether, results support the hypothesis of axolemma mechanoporation as a cell-injury trigger. Moreover, for the first time the interconnection between the axolemma and the MT bundle is shown to play a role in damage localization. The proposed FE axonal model is a valuable tool to understand the axonal injury mechanism from a mechanical perspective and could be used in turn for the definition of well-informed injury criteria at the tissue and organ level.
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Affiliation(s)
- Annaclaudia Montanino
- Division of Neuronic Engineering, Royal Institute of Technology (KTH), Huddinge, Sweden
| | - Svein Kleiven
- Division of Neuronic Engineering, Royal Institute of Technology (KTH), Huddinge, Sweden
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42
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Abstract
Intermediate filaments (IFs) are one of the three major elements of the cytoskeleton. Their stability, intrinsic mechanical properties, and cell type-specific expression patterns distinguish them from actin and microtubules. By providing mechanical support, IFs protect cells from external forces and participate in cell adhesion and tissue integrity. IFs form an extensive and elaborate network that connects the cell cortex to intracellular organelles. They act as a molecular scaffold that controls intracellular organization. However, IFs have been revealed as much more than just rigid structures. Their dynamics is regulated by multiple signaling cascades and appears to contribute to signaling events in response to cell stress and to dynamic cellular functions such as mitosis, apoptosis, and migration.
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Affiliation(s)
- Sandrine Etienne-Manneville
- Institut Pasteur Paris, CNRS UMR 3691, Cell Polarity, Migration and Cancer Unit, Equipe Labellisée Ligue Contre le Cancer, Paris Cedex 15, France;
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43
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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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44
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Mechanics, Structure and Function of Biopolymer Condensates. J Mol Biol 2018; 430:4754-4761. [PMID: 29913159 DOI: 10.1016/j.jmb.2018.06.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 06/08/2018] [Accepted: 06/11/2018] [Indexed: 11/22/2022]
Abstract
The spontaneous nature of biopolymer phase separation in cells entails that the resulting condensates can be thermodynamic machines, which, in the process of condensing, can take on distinct forms themselves and deform neighboring cellular structures. We introduce here general notions of material and mechanical properties of protein condensates with an emphasis on how molecular arrangements and intermolecular interaction within condensates determine their ability to do work on their surroundings. We further propose functional implications of these concepts to cellular and subcellular morphology and biogenesis.
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45
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Somayaji MR, Przekwas AJ, Gupta RK. Combination Therapy for Multi-Target Manipulation of Secondary Brain Injury Mechanisms. Curr Neuropharmacol 2018; 16:484-504. [PMID: 28847295 PMCID: PMC6018188 DOI: 10.2174/1570159x15666170828165711] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 02/10/2017] [Accepted: 03/28/2017] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) is a major healthcare problem that affects millions of people worldwide. Despite advances in understanding and developing preventative and treatment strategies using preclinical animal models, clinical trials to date have failed, and a 'magic bullet' for effectively treating TBI-induced damage does not exist. Thus, novel pharmacological strategies to effectively manipulate the complex and heterogeneous pathophysiology of secondary injury mechanisms are needed. Given that goal, this paper discusses the relevance and advantages of combination therapies (COMTs) for 'multi-target manipulation' of the secondary injury cascade by administering multiple drugs to achieve an optimal therapeutic window of opportunity (e.g., temporally broad window) and compares these regimens to monotherapies that manipulate a single target with a single drug at a given time. Furthermore, we posit that integrated mechanistic multiscale models that combine primary injury biomechanics, secondary injury mechanobiology/neurobiology, physiology, pharmacology and mathematical programming techniques could account for vast differences in the biological space and time scales and help to accelerate drug development, to optimize pharmacological COMT protocols and to improve treatment outcomes.
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Affiliation(s)
| | | | - Raj K. Gupta
- Department of Defense Blast Injury Research Program Coordinating Office, U.S. Army Medical Research and Materiel Command, Fort Detrick, MD, USA
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46
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Gu Y, Jukkola P, Wang Q, Esparza T, Zhao Y, Brody D, Gu C. Polarity of varicosity initiation in central neuron mechanosensation. J Cell Biol 2017; 216:2179-2199. [PMID: 28606925 PMCID: PMC5496611 DOI: 10.1083/jcb.201606065] [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: 06/13/2016] [Revised: 01/17/2017] [Accepted: 04/20/2017] [Indexed: 12/22/2022] Open
Abstract
Little is known about mechanical regulation of morphological and functional polarity of central neurons. In this study, we report that mechanical stress specifically induces varicosities in the axons but not the dendrites of central neurons by activating TRPV4, a Ca2+/Na+-permeable mechanosensitive channel. This process is unexpectedly rapid and reversible, consistent with the formation of axonal varicosities in vivo induced by mechanical impact in a mouse model of mild traumatic brain injury. In contrast, prolonged stimulation of glutamate receptors induces varicosities in dendrites but not in axons. We further show that axonal varicosities are induced by persistent Ca2+ increase, disassembled microtubules (MTs), and subsequently reversible disruption of axonal transport, and are regulated by stable tubulin-only polypeptide, an MT-associated protein. Finally, axonal varicosity initiation can trigger action potentials to antidromically propagate to the soma in retrograde signaling. Therefore, our study demonstrates a new feature of neuronal polarity: axons and dendrites preferentially respond to physical and chemical stresses, respectively.
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Affiliation(s)
- Yuanzheng Gu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH
| | - Peter Jukkola
- Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH
| | - Qian Wang
- Biomedical Engineering Department, The Ohio State University, Columbus, OH
| | - Thomas Esparza
- Department of Neurology, Washington University, St. Louis, MO
| | - Yi Zhao
- Biomedical Engineering Department, The Ohio State University, Columbus, OH
| | - David Brody
- Department of Neurology, Washington University, St. Louis, MO
| | - Chen Gu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH .,Biomedical Sciences Graduate Program, The Ohio State University, Columbus, OH
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47
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Persistence of fan-shaped keratocytes is a matrix-rigidity-dependent mechanism that requires α 5β 1 integrin engagement. Sci Rep 2016; 6:34141. [PMID: 27678055 PMCID: PMC5039689 DOI: 10.1038/srep34141] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Accepted: 09/05/2016] [Indexed: 12/27/2022] Open
Abstract
Despite the importance of matrix rigidity on cell functions, many aspects of the mechanosensing process in highly migratory cells remain elusive. Here, we studied the migration of highly motile keratocytes on culture substrates with similar biochemical properties and rigidities spanning the range between soft tissues (~kPa) and stiff culture substrates (~GPa). We show that morphology, polarization and persistence of motile keratocytes are regulated by the matrix stiffness over seven orders of magnitude, without changing the cell spreading area. Increasing the matrix rigidity leads to more F-actin in the lamellipodia and to the formation of mature contractile actomyosin fibers that control the cell rear retraction. Keratocytes remain rounded and form nascent adhesions on compliant substrates, whereas large and uniformly distributed focal adhesions are formed on fan-shaped keratocytes migrating on rigid surfaces. By combining poly-L-lysine, fibronectin and vitronectin coatings with selective blocking of αvβ3 or α5β1 integrins, we show that αVβ3 integrins permit the spreading of keratocytes but are not sufficient for polarization and rigidity sensing that require the engagement of α5β1 integrins. Our study demonstrates a matrix rigidity-dependent regulation of the directional persistence in motile keratocytes and refines the role of αvβ3 and α5β1 integrins in the molecular clutch model.
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48
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In silico synchronization reveals regulators of nuclear ruptures in lamin A/C deficient model cells. Sci Rep 2016; 6:30325. [PMID: 27461848 PMCID: PMC4962089 DOI: 10.1038/srep30325] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 07/04/2016] [Indexed: 11/23/2022] Open
Abstract
The nuclear lamina is a critical regulator of nuclear structure and function. Nuclei from laminopathy patient cells experience repetitive disruptions of the nuclear envelope, causing transient intermingling of nuclear and cytoplasmic components. The exact causes and consequences of these events are not fully understood, but their stochastic occurrence complicates in-depth analyses. To resolve this, we have established a method that enables quantitative investigation of spontaneous nuclear ruptures, based on co-expression of a firmly bound nuclear reference marker and a fluorescent protein that shuttles between the nucleus and cytoplasm during ruptures. Minimally invasive imaging of both reporters, combined with automated tracking and in silico synchronization of individual rupture events, allowed extracting information on rupture frequency and recovery kinetics. Using this approach, we found that rupture frequency correlates inversely with lamin A/C levels, and can be reduced in genome-edited LMNA knockout cells by blocking actomyosin contractility or inhibiting the acetyl-transferase protein NAT10. Nuclear signal recovery followed a kinetic that is co-determined by the severity of the rupture event, and could be prolonged by knockdown of the ESCRT-III complex component CHMP4B. In conclusion, our approach reveals regulators of nuclear rupture induction and repair, which may have critical roles in disease development.
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49
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Ayala YA, Pontes B, Ether DS, Pires LB, Araujo GR, Frases S, Romão LF, Farina M, Moura-Neto V, Viana NB, Nussenzveig HM. Rheological properties of cells measured by optical tweezers. BMC BIOPHYSICS 2016; 9:5. [PMID: 27340552 PMCID: PMC4917937 DOI: 10.1186/s13628-016-0031-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 06/10/2016] [Indexed: 11/10/2022]
Abstract
BACKGROUND The viscoelastic properties of cells have been investigated by a variety of techniques. However, the experimental data reported in literature for viscoelastic moduli differ by up to three orders of magnitude. This has been attributed to differences in techniques and models for cell response as well as to the natural variability of cells. RESULTS In this work we develop and apply a new methodology based on optical tweezers to investigate the rheological behavior of fibroblasts, neurons and astrocytes in the frequency range from 1Hz to 35Hz, determining the storage and loss moduli of their membrane-cortex complex. To avoid distortions associated with cell probing techniques, we use a previously developed method that takes into account the influence of under bead cell thickness and bead immersion. These two parameters were carefully measured for the three cell types used. Employing the soft glass rheology model, we obtain the scaling exponent and the Young's modulus for each cell type. The obtained viscoelastic moduli are in the order of Pa. Among the three cell types, astrocytes have the lowest elastic modulus, while neurons and fibroblasts exhibit a more solid-like behavior. CONCLUSIONS Although some discrepancies with previous results remain and may be inevitable in view of natural variability, the methodology developed in this work allows us to explore the viscoelastic behavior of the membrane-cortex complex of different cell types as well as to compare their viscous and elastic moduli, obtained under identical and well-defined experimental conditions, relating them to the cell functions.
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Affiliation(s)
- Yareni A Ayala
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 Brazil
| | - Bruno Pontes
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil
| | - Diney S Ether
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 Brazil
| | - Luis B Pires
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 Brazil
| | - Glauber R Araujo
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil
| | - Susana Frases
- Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil
| | - Luciana F Romão
- Universidade Federal do Rio de Janeiro - Pólo de Xerém, Duque de Caxias, Rio de Janeiro 25245-390 Brazil
| | - Marcos Farina
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil
| | - Vivaldo Moura-Neto
- Instituto Estadual do Cérebro Paulo Niemeyer, Rio de Janeiro, Rio de Janeiro 20231-092 Brazil
| | - Nathan B Viana
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 Brazil
| | - H Moysés Nussenzveig
- LPO-COPEA, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-902 Brazil.,Instituto de Física, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro 21941-972 Brazil
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50
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Lantoine J, Grevesse T, Villers A, Delhaye G, Mestdagh C, Versaevel M, Mohammed D, Bruyère C, Alaimo L, Lacour SP, Ris L, Gabriele S. Matrix stiffness modulates formation and activity of neuronal networks of controlled architectures. Biomaterials 2016; 89:14-24. [DOI: 10.1016/j.biomaterials.2016.02.041] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Revised: 02/14/2016] [Accepted: 02/23/2016] [Indexed: 11/16/2022]
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