301
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Fal K, Asnacios A, Chabouté ME, Hamant O. Nuclear envelope: a new frontier in plant mechanosensing? Biophys Rev 2017; 9:389-403. [PMID: 28801801 PMCID: PMC5578935 DOI: 10.1007/s12551-017-0302-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/28/2017] [Indexed: 02/07/2023] Open
Abstract
In animals, it is now well established that forces applied at the cell surface are propagated through the cytoskeleton to the nucleus, leading to deformations of the nuclear structure and, potentially, to modification of gene expression. Consistently, altered nuclear mechanics has been related to many genetic disorders, such as muscular dystrophy, cardiomyopathy and progeria. In plants, the integration of mechanical signals in cell and developmental biology has also made great progress. Yet, while the link between cell wall stresses and cytoskeleton is consolidated, such cortical mechanical cues have not been integrated with the nucleoskeleton. Here, we propose to take inspiration from studies on animal nuclei to identify relevant methods amenable to probing nucleus mechanics and deformation in plant cells, with a focus on microrheology. To identify potential molecular targets, we also compare the players at the nuclear envelope, namely lamina and LINC complex, in both plant and animal nuclei. Understanding how mechanical signals are transduced to the nucleus across kingdoms will likely have essential implications in development (e.g. how mechanical cues add robustness to gene expression patterns), in the nucleoskeleton-cytoskeleton nexus (e.g. how stress is propagated in turgid/walled cells), as well as in transcriptional control, chromatin biology and epigenetics.
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Affiliation(s)
- Kateryna Fal
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 69342, Lyon, France
| | - Atef Asnacios
- Laboratoire Matières et Systèmes Complexes, Université Paris-Diderot and CNRS, UMR 7057, Sorbonne Paris Cité, Paris, France
| | - Marie-Edith Chabouté
- Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Olivier Hamant
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 69342, Lyon, France.
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302
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Actomyosin and vimentin cytoskeletal networks regulate nuclear shape, mechanics and chromatin organization. Sci Rep 2017; 7:5219. [PMID: 28701767 PMCID: PMC5507932 DOI: 10.1038/s41598-017-05467-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 05/31/2017] [Indexed: 01/07/2023] Open
Abstract
The regulation of nuclear state by the cytoskeleton is an important part of cellular function. Actomyosin stress fibres, microtubules and intermediate filaments have distinct and complementary roles in integrating the nucleus into its environment and influencing its mechanical state. However, the interconnectedness of cytoskeletal networks makes it difficult to dissect their individual effects on the nucleus. We use simple image analysis approaches to characterize nuclear state, estimating nuclear volume, Poisson's ratio, apparent elastic modulus and chromatin condensation. By combining them with cytoskeletal quantification, we assess how cytoskeletal organization regulates nuclear state. We report for a number of cell types that nuclei display auxetic properties. Furthermore, stress fibres and intermediate filaments modulate the mechanical properties of the nucleus and also chromatin condensation. Conversely, nuclear volume and its gross morphology are regulated by intracellular outward pulling forces exerted by myosin. The modulation exerted by the cytoskeleton onto the nucleus results in changes that are of similar magnitude to those observed when the nucleus is altered intrinsically, inducing chromatin decondensation or cell differentiation. Our approach allows pinpointing the contribution of distinct cytoskeletal proteins to nuclear mechanical state in physio- and pathological conditions, furthering our understanding of a key aspect of cellular behaviour.
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303
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Schoen I, Aires L, Ries J, Vogel V. Nanoscale invaginations of the nuclear envelope: Shedding new light on wormholes with elusive function. Nucleus 2017; 8:506-514. [PMID: 28686487 DOI: 10.1080/19491034.2017.1337621] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Recent advances in fluorescence microscopy have opened up new possibilities to investigate chromosomal and nuclear 3D organization on the nanoscale. We here discuss their potential for elucidating topographical details of the nuclear lamina. Single molecule localization microscopy (SMLM) in combination with immunostainings of lamina proteins readily reveals tube-like invaginations with a diameter of 100-500 nm. Although these invaginations have been established as a frequent and general feature of interphase nuclei across different cell types, their formation mechanism and function have remained largely elusive. We critically review the current state of research, propose possible connections to lamina associated domains (LADs), and revisit the discussion about the potential role of these invaginations for accelerating mRNA nuclear export. Illustrative studies using 3D super-resolution imaging are shown and will be instrumental to decipher the physiological role of these nanoscale invaginations.
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Affiliation(s)
- Ingmar Schoen
- a ETH Zurich, Department of Health Sciences and Technology, Laboratory of Applied Mechanobiology , Zurich , Switzerland
| | - Lina Aires
- a ETH Zurich, Department of Health Sciences and Technology, Laboratory of Applied Mechanobiology , Zurich , Switzerland
| | - Jonas Ries
- b European Molecular Biology Laboratory, Cell Biology and Biophysics Unit , Heidelberg , Germany
| | - Viola Vogel
- a ETH Zurich, Department of Health Sciences and Technology, Laboratory of Applied Mechanobiology , Zurich , Switzerland
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304
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Inside the Cell: Integrins as New Governors of Nuclear Alterations? Cancers (Basel) 2017; 9:cancers9070082. [PMID: 28684679 PMCID: PMC5532618 DOI: 10.3390/cancers9070082] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 06/26/2017] [Accepted: 07/04/2017] [Indexed: 02/07/2023] Open
Abstract
Cancer cell migration is a complex process that requires coordinated structural changes and signals in multiple cellular compartments. The nucleus is the biggest and stiffest organelle of the cell and might alter its physical properties to allow cancer cell movement. Integrins are transmembrane receptors that mediate cell-cell and cell-extracellular matrix interactions, which regulate numerous intracellular signals and biological functions under physiological conditions. Moreover, integrins orchestrate changes in tumor cells and their microenvironment that lead to cancer growth, survival and invasiveness. Most of the research efforts have focused on targeting integrin-mediated adhesion and signaling. Recent exciting data suggest the crucial role of integrins in controlling internal cellular structures and nuclear alterations during cancer cell migration. Here we review the emerging role of integrins in nuclear biology. We highlight increasing evidence that integrins are critical for changes in multiple nuclear components, the positioning of the nucleus and its mechanical properties during cancer cell migration. Finally, we discuss how integrins are integral proteins linking the plasma membrane and the nucleus, and how they control cell migration to enable cancer invasion and infiltration. The functional connections between these cell receptors and the nucleus will serve to define new attractive therapeutic targets.
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305
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Chan CJ, Li W, Cojoc G, Guck J. Volume Transitions of Isolated Cell Nuclei Induced by Rapid Temperature Increase. Biophys J 2017; 112:1063-1076. [PMID: 28355535 PMCID: PMC5374986 DOI: 10.1016/j.bpj.2017.01.022] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 01/10/2017] [Accepted: 01/17/2017] [Indexed: 02/07/2023] Open
Abstract
Understanding the physical mechanisms governing nuclear mechanics is important as it can impact gene expression and development. However, how cell nuclei respond to external cues such as heat is not well understood. Here, we studied the material properties of isolated nuclei in suspension using an optical stretcher. We demonstrate that isolated nuclei regulate their volume in a highly temperature-sensitive manner. At constant temperature, isolated nuclei behaved like passive, elastic and incompressible objects, whose volume depended on the pH and ionic conditions. When the temperature was increased suddenly by even a few degrees Kelvin, nuclei displayed a repeatable and reversible temperature-induced volume transition, whose sign depended on the valency of the solvent. Such phenomenon is not observed for nuclei subjected to slow heating. The transition temperature could be shifted by adiabatic changes of the ambient temperature, and the magnitude of temperature-induced volume transition could be modulated by modifying the chromatin compaction state and remodeling processes. Our findings reveal that the cell nucleus can be viewed as a highly charged polymer gel with intriguing thermoresponsive properties, which might play a role in nuclear volume regulation and thermosensing in living cells.
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Affiliation(s)
- Chii J Chan
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
| | - Wenhong Li
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Gheorghe Cojoc
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Jochen Guck
- Cavendish Laboratory, Department of Physics, University of Cambridge, Cambridge, United Kingdom; Biotechnology Center, Technische Universität Dresden, Dresden, Germany.
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306
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Cartagena-Rivera AX, Logue JS, Waterman CM, Chadwick RS. Actomyosin Cortical Mechanical Properties in Nonadherent Cells Determined by Atomic Force Microscopy. Biophys J 2017; 110:2528-2539. [PMID: 27276270 PMCID: PMC4906360 DOI: 10.1016/j.bpj.2016.04.034] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 03/29/2016] [Accepted: 04/25/2016] [Indexed: 12/18/2022] Open
Abstract
The organization of filamentous actin and myosin II molecular motor contractility is known to modify the mechanical properties of the cell cortical actomyosin cytoskeleton. Here we describe a novel method, to our knowledge, for using force spectroscopy approach curves with tipless cantilevers to determine the actomyosin cortical tension, elastic modulus, and intracellular pressure of nonadherent cells. We validated the method by measuring the surface tension of water in oil microdrops deposited on a glass surface. We extracted an average tension of T ∼ 20.25 nN/μm, which agrees with macroscopic experimental methods. We then measured cortical mechanical properties in nonadherent human foreskin fibroblasts and THP-1 human monocytes before and after pharmacological perturbations of actomyosin activity. Our results show that myosin II activity and actin polymerization increase cortex tension and intracellular pressure, whereas branched actin networks decreased them. Interestingly, myosin II activity stiffens the cortex and branched actin networks soften it, but actin polymerization has no effect on cortex stiffness. Our method is capable of detecting changes in cell mechanical properties in response to perturbations of the cytoskeleton, allowing characterization with physically relevant parameters. Altogether, this simple method should be of broad application for deciphering the molecular regulation of cell cortical mechanical properties.
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Affiliation(s)
- Alexander X Cartagena-Rivera
- Laboratory of Cellular Biology, Section on Auditory Mechanics, National Institute on Deafness and Other Communication Disorders, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Jeremy S Logue
- Laboratory of Cellular Biology, Section on Auditory Mechanics, National Institute on Deafness and Other Communication Disorders, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland; Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Clare M Waterman
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Richard S Chadwick
- Laboratory of Cellular Biology, Section on Auditory Mechanics, National Institute on Deafness and Other Communication Disorders, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland.
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307
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Ultrasound induced strain cytoskeleton rearrangement: An experimental and simulation study. J Biomech 2017; 60:39-47. [DOI: 10.1016/j.jbiomech.2017.06.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 06/05/2017] [Accepted: 06/06/2017] [Indexed: 11/24/2022]
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308
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Jayo A, Malboubi M, Antoku S, Chang W, Ortiz-Zapater E, Groen C, Pfisterer K, Tootle T, Charras G, Gundersen GG, Parsons M. Fascin Regulates Nuclear Movement and Deformation in Migrating Cells. Dev Cell 2017; 38:371-83. [PMID: 27554857 PMCID: PMC4997957 DOI: 10.1016/j.devcel.2016.07.021] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 05/25/2016] [Accepted: 07/25/2016] [Indexed: 12/16/2022]
Abstract
Fascin is an F-actin-bundling protein shown to stabilize filopodia and regulate adhesion dynamics in migrating cells, and its expression is correlated with poor prognosis and increased metastatic potential in a number of cancers. Here, we identified the nuclear envelope protein nesprin-2 as a binding partner for fascin in a range of cell types in vitro and in vivo. Nesprin-2 interacts with fascin through a direct, F-actin-independent interaction, and this binding is distinct and separable from a role for fascin within filopodia at the cell periphery. Moreover, disrupting the interaction between fascin and nesprin-2 C-terminal domain leads to specific defects in F-actin coupling to the nuclear envelope, nuclear movement, and the ability of cells to deform their nucleus to invade through confined spaces. Together, our results uncover a role for fascin that operates independently of filopodia assembly to promote efficient cell migration and invasion. Fascin binds directly to nesprin-2 at the nuclear envelope Fascin-nesprin-2 binding occurs independently of fascin-actin bundling The fascin-nesprin-2 complex regulates nuclear movement in migration Uncoupling the fascin-nesprin complex reduces nuclear deformation and cell invasion
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Affiliation(s)
- Asier Jayo
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guys Campus, London SE1 1UL, UK
| | - Majid Malboubi
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK
| | - Susumu Antoku
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Wakam Chang
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Elena Ortiz-Zapater
- Division of Asthma, Allergy & Lung Biology, King's College London, 5th Floor Tower Wing, Guy's Hospital Campus, London SE1 1UL, UK
| | - Christopher Groen
- Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Karin Pfisterer
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guys Campus, London SE1 1UL, UK
| | - Tina Tootle
- Anatomy and Cell Biology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Guillaume Charras
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, Columbia University, New York, NY 10032, USA
| | - Maddy Parsons
- Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guys Campus, London SE1 1UL, UK.
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309
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Fenelon KD, Hopyan S. Structural components of nuclear integrity with gene regulatory potential. Curr Opin Cell Biol 2017. [PMID: 28641117 DOI: 10.1016/j.ceb.2017.06.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The nucleus is a mechanosensitive and load-bearing structure. Structural components of the nucleus interact to maintain nuclear integrity and have become subjects of exciting research that is relevant to cell and developmental biology. Here we outline the boundaries of what is known about key architectural elements within the nucleus and highlight their potential structural and transcriptional regulatory functions.
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Affiliation(s)
- Kelli D Fenelon
- Program in Developmental and Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada
| | - Sevan Hopyan
- Program in Developmental and Stem Cell Biology, Research Institute, The Hospital for Sick Children, Toronto, ON M5G 0A4, Canada; Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada; Division of Orthopaedic Surgery, Hospital for Sick Children and University of Toronto, M5G 1X8, Canada.
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310
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Balikov DA, Brady SK, Ko UH, Shin JH, de Pereda JM, Sonnenberg A, Sung HJ, Lang MJ. The nesprin-cytoskeleton interface probed directly on single nuclei is a mechanically rich system. Nucleus 2017. [PMID: 28640691 DOI: 10.1080/19491034.2017.1322237] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
The cytoskeleton provides structure and plays an important role in cellular function such as migration, resisting compression forces, and transport. The cytoskeleton also reacts to physical cues such as fluid shear stress or extracellular matrix remodeling by reorganizing filament associations, most commonly focal adhesions and cell-cell cadherin junctions. These mechanical stimuli can result in genome-level changes, and the physical connection of the cytoskeleton to the nucleus provides an optimal conduit for signal transduction by interfacing with nuclear envelope proteins, called nesprins, within the LINC (linker of the nucleus to the cytoskeleton) complex. Using single-molecule on single nuclei assays, we report that the interactions between the nucleus and the cytoskeleton, thought to be nesprin-cytoskeleton interactions, are highly sensitive to force magnitude and direction depending on whether cells are historically interfaced with the matrix or with cell aggregates. Application of ∼10-30 pN forces to these nesprin linkages yielded structural transitions, with a base transition size of 5-6 nm, which are speculated to be associated with partial unfoldings of the spectrin domains of the nesprins and/or structural changes of histones within the nucleus.
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Affiliation(s)
- Daniel A Balikov
- a Department of Biomedical Engineering , Vanderbilt University , Nashville , TN , USA
| | - Sonia K Brady
- b Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , TN , USA
| | - Ung Hyun Ko
- c Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology , Daejeon , Korea
| | - Jennifer H Shin
- c Department of Mechanical Engineering , Korea Advanced Institute of Science and Technology , Daejeon , Korea
| | - Jose M de Pereda
- d Instituto de Biologia Molecular y Celular del Cancer, Consejo Superior de Investigaciones Cientificas , University of Salamanca , Salamanca , Spain
| | | | - Hak-Joon Sung
- a Department of Biomedical Engineering , Vanderbilt University , Nashville , TN , USA.,f Division of Cardiovascular Medicine, Department of Medicine , Vanderbilt University Medical Center , Nashville , TN , USA.,g Severance Biomedical Science Institute, College of Medicine , Yonsei University , Seoul , Republic of Korea
| | - Matthew J Lang
- b Department of Chemical and Biomolecular Engineering , Vanderbilt University , Nashville , TN , USA.,h Department of Molecular Physiology and Biophysics , Vanderbilt University Medical Center , Nashville , TN , USA.,i SMART-BioSystems and Micromechanics , National University of Singapore , Singapore
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311
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Athirasala A, Hirsch N, Buxboim A. Nuclear mechanotransduction: sensing the force from within. Curr Opin Cell Biol 2017. [PMID: 28641092 DOI: 10.1016/j.ceb.2017.04.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The cell nucleus is a hallmark of eukaryotic evolution, where gene expression is regulated and the genome is replicated and repaired. Yet, in addition to complex molecular processes, the nucleus has also evolved to serve physical tasks that utilize its optical and mechanical properties. Nuclear mechanotransduction of externally applied forces and extracellular stiffness is facilitated by the physical connectivity of the extracellular environment, the cytoskeleton and the nucleoskeletal matrix of lamins and chromatin. Nuclear mechanosensor elements convert applied tension into biochemical cues that activate downstream signal transduction pathways. Mechanoregulatory networks stabilize a contractile cell state with feedback to matrix, cell adhesions and cytoskeletal elements. Recent advances have thus provided mechanistic insights into how forces are sensed from within, that is, in the nucleus where cell-fate decision-making is performed.
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Affiliation(s)
- Avathamsa Athirasala
- Alexander Grass Center for Bioengineering, School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Nivi Hirsch
- Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel
| | - Amnon Buxboim
- Alexander Grass Center for Bioengineering, School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel; Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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312
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Liu X, Liu R, Gu Y, Ding J. Nonmonotonic Self-Deformation of Cell Nuclei on Topological Surfaces with Micropillar Array. ACS APPLIED MATERIALS & INTERFACES 2017; 9:18521-18530. [PMID: 28514142 DOI: 10.1021/acsami.7b04027] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Cells respond to the mechanical signals from their surroundings and integrate physiochemical signals to initiate intricate mechanochemical processes. While many studies indicate that topological features of biomaterials impact cellular behaviors profoundly, little research has focused on the nuclear response to a mechanical force generated by a topological surface. Here, we fabricated a polymeric micropillar array with an appropriate dimension to induce a severe self-deformation of cell nuclei and investigated how the nuclear shape changed over time. Intriguingly, the nuclei of mesenchymal stem cells (MSCs) on the poly(lactide-co-glycolide) (PLGA) micropillars exhibited a significant initial deformation followed by a partial recovery, which led to an "overshoot" phenomenon. The treatment of cytochalasin D suppressed the recovery of nuclei, which indicated the involvement of actin cytoskeleton in regulating the recovery at the second stage of nuclear deformation. Additionally, we found that MSCs exhibited different overshoot extents from their differentiated lineage, osteoblasts. These findings enrich the understanding of the role of the cell nucleus in mechanotransduction. As the first quantitative report on nonmonotonic kinetic process of self-deformation of a cell organelle on biomaterials with unique topological surfaces, this study sheds new insight into cell-biomaterial interactions.
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Affiliation(s)
- Xiangnan Liu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University , Shanghai 200433, China
| | - Ruili Liu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University , Shanghai 200433, China
| | - Yexin Gu
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University , Shanghai 200433, China
| | - Jiandong Ding
- State Key Laboratory of Molecular Engineering of Polymers, Department of Macromolecular Science, Fudan University , Shanghai 200433, China
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313
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Willer MK, Carroll CW. Substrate stiffness-dependent regulation of the SRF-Mkl1 co-activator complex requires the inner nuclear membrane protein Emerin. J Cell Sci 2017; 130:2111-2118. [PMID: 28576971 DOI: 10.1242/jcs.197517] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 05/13/2017] [Indexed: 01/05/2023] Open
Abstract
The complex comprising serum response factor (SRF) and megakaryoblastic leukemia 1 protein (Mkl1) promotes myofibroblast differentiation during wound healing. SRF-Mkl1 is sensitive to the mechanical properties of the extracellular environment; but how cells sense and transduce mechanical cues to modulate SRF-Mkl1-dependent gene expression is not well understood. Here, we demonstrate that the nuclear lamina-associated inner nuclear membrane protein Emerin stimulates SRF-Mkl1-dependent gene activity in a substrate stiffness-dependent manner. Specifically, Emerin was required for Mkl1 nuclear accumulation and maximal SRF-Mkl1-dependent gene expression in response to serum stimulation of cells grown on stiff substrates but was dispensable on more compliant substrates. Focal adhesion area was also reduced in cells lacking Emerin, consistent with a role for Emerin in sensing substrate stiffness. Expression of a constitutively active form of Mkl1 bypassed the requirement for Emerin in SRF-Mkl1-dependent gene expression and reversed the focal adhesion defects evident in EmdKO fibroblasts. Together, these data indicate that Emerin, a conserved nuclear lamina protein, couples extracellular matrix mechanics and SRF-Mkl1-dependent transcription.
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Affiliation(s)
- Margaret K Willer
- Dept. Of Cell Biology, Yale School of Medicine, New Haven, CT 06520, USA
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314
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Moujaber O, Omran N, Kodiha M, Pié B, Cooper E, Presley JF, Stochaj U. Data on the association of the nuclear envelope protein Sun1 with nucleoli. Data Brief 2017; 13:115-123. [PMID: 28580408 PMCID: PMC5447391 DOI: 10.1016/j.dib.2017.05.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 11/01/2022] Open
Abstract
SUN proteins participate in diverse cellular activities, many of which are connected to the nuclear envelope. Recently, the family member SUN1 has been linked to novel biological activities. These include the regulation of nucleoli, intranuclear compartments that assemble ribosomal subunits. We show that SUN1 associates with nucleoli in several mammalian epithelial cell lines. This nucleolar localization is not shared by all cell types, as SUN1 concentrates at the nuclear envelope in ganglionic neurons and non-neuronal satellite cells. Database analyses and Western blotting emphasize the complexity of SUN1 protein profiles in different mammalian cells. We constructed a STRING network which identifies SUN1-related proteins as part of a larger network that includes several nucleolar proteins. Taken together, the current data highlight the diversity of SUN1 proteins and emphasize the possible links between SUN1 and nucleoli.
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Affiliation(s)
| | - Nawal Omran
- Physiology, McGill University, Montreal, Canada
| | | | | | | | - John F Presley
- Anatomy & Cell Biology, McGill University, Montreal, Canada
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315
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Maninova M, Caslavsky J, Vomastek T. The assembly and function of perinuclear actin cap in migrating cells. PROTOPLASMA 2017; 254:1207-1218. [PMID: 28101692 DOI: 10.1007/s00709-017-1077-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 01/09/2017] [Indexed: 05/24/2023]
Abstract
Stress fibers are actin bundles encompassing actin filaments, actin-crosslinking, and actin-associated proteins that represent the major contractile system in the cell. Different types of stress fibers assemble in adherent cells, and they are central to diverse cellular processes including establishment of the cell shape, morphogenesis, cell polarization, and migration. Stress fibers display specific cellular organization and localization, with ventral fibers present at the basal side, and dorsal fibers and transverse actin arcs rising at the cell front from the ventral to the dorsal side and toward the nucleus. Perinuclear actin cap fibers are a specific subtype of stress fibers that rise from the leading edge above the nucleus and terminate at the cell rear forming a dome-like structure. Perinuclear actin cap fibers are fixed at three points: both ends are anchored in focal adhesions, while the central part is physically attached to the nucleus and nuclear lamina through the linker of nucleoskeleton and cytoskeleton (LINC) complex. Here, we discuss recent work that provides new insights into the mechanism of assembly and the function of these actin stress fibers that directly link extracellular matrix and focal adhesions with the nuclear envelope.
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Affiliation(s)
- Miloslava Maninova
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic
| | - Josef Caslavsky
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic
| | - Tomas Vomastek
- Institute of Microbiology, Academy of Sciences of the Czech Republic, Videnska 1083, 142 00, Prague, Czech Republic.
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316
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Abstract
The eukaryotic nucleus is enclosed by the nuclear envelope, which is perforated by the nuclear pores, the gateways of macromolecular exchange between the nucleoplasm and cytoplasm. The nucleoplasm is organized in a complex three-dimensional fashion that changes over time and in response to stimuli. Within the cell, the nucleus must be viewed as an organelle (albeit a gigantic one) that is a recipient of cytoplasmic forces and capable of morphological and positional dynamics. The most dramatic reorganization of this organelle occurs during mitosis and meiosis. Although many of these aspects are less well understood for the nuclei of plants than for those of animals or fungi, several recent discoveries have begun to place our understanding of plant nuclei firmly into this broader cell-biological context.
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Affiliation(s)
- Iris Meier
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio 43210;
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
| | | | - David E Evans
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
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317
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Shimamoto Y, Tamura S, Masumoto H, Maeshima K. Nucleosome-nucleosome interactions via histone tails and linker DNA regulate nuclear rigidity. Mol Biol Cell 2017; 28:1580-1589. [PMID: 28428255 PMCID: PMC5449155 DOI: 10.1091/mbc.e16-11-0783] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/15/2017] [Accepted: 04/05/2017] [Indexed: 12/15/2022] Open
Abstract
A force-calibrated microneedle setup and controlled biochemical perturbation reveal that chromatin acts as a spring-like mechanical module that controls the rigidity of cell nuclei. The underlying molecular mechanism involves linker DNA and internucleosomal interaction via histone tails. Cells, as well as the nuclei inside them, experience significant mechanical stress in diverse biological processes, including contraction, migration, and adhesion. The structural stability of nuclei must therefore be maintained in order to protect genome integrity. Despite extensive knowledge on nuclear architecture and components, however, the underlying physical and molecular mechanisms remain largely unknown. We address this by subjecting isolated human cell nuclei to microneedle-based quantitative micromanipulation with a series of biochemical perturbations of the chromatin. We find that the mechanical rigidity of nuclei depends on the continuity of the nucleosomal fiber and interactions between nucleosomes. Disrupting these chromatin features by varying cation concentration, acetylating histone tails, or digesting linker DNA results in loss of nuclear rigidity. In contrast, the levels of key chromatin assembly factors, including cohesin, condensin II, and CTCF, and a major nuclear envelope protein, lamin, are unaffected. Together with in situ evidence using living cells and a simple mechanical model, our findings reveal a chromatin-based regulation of the nuclear mechanical response and provide insight into the significance of local and global chromatin structures, such as those associated with interdigitated or melted nucleosomal fibers.
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Affiliation(s)
- Yuta Shimamoto
- Quantitative Mechanobiology Laboratory, Center for Frontier Research, National Institute of Genetics, Mishima 411-8540, Japan .,Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima 411-8540, Japan.,PRIME, Japan Agency for Medical Research and Development, Tokyo 100-0004, Japan
| | - Sachiko Tamura
- Biological Macromolecules Laboratory, Structural Biology Center, National Institute of Genetics, Mishima 411-8540, Japan
| | - Hiroshi Masumoto
- Biomedical Research Support Center, Nagasaki University School of Medicine; Nagasaki 852-8523, Japan
| | - Kazuhiro Maeshima
- Department of Genetics, School of Life Science, Sokendai (Graduate University for Advanced Studies), Mishima 411-8540, Japan .,PRIME, Japan Agency for Medical Research and Development, Tokyo 100-0004, Japan
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318
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Sakamoto N, Ogawa M, Sadamoto K, Takeuchi M, Kataoka N. Mechanical Role of Nesprin-1-Mediated Nucleus-Actin Filament Binding in Cyclic Stretch-Induced Fibroblast Elongation. Cell Mol Bioeng 2017; 10:327-338. [PMID: 31719867 DOI: 10.1007/s12195-017-0487-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 04/07/2017] [Indexed: 11/26/2022] Open
Abstract
The intracellular mechanical link tethering the nucleus to the cytoskeleton has been suggested to be the linker of the nucleoskeleton and cytoskeleton (LINC) complex. Previous studies have reported that knockdown of nesprin-1, a component of the LINC complex that directly binds to actin filaments, suppresses cellular morphological response to mechanical stimuli. The relation between nesprin-1 knockdown and cellular morphological changes, however, remains unclear. In this study, we examined the mechanical role of nucleus-actin filament binding in morphological changes of fibroblasts exposed to cyclic stretching. After exposure to 10% cyclic stretching for 6 h, fibroblasts transfected with nesprin-1-specific small interfering RNA showed fewer elongated shapes compared with non-transfected cells. To further examine the mechanical role of the nucleus and nucleus-bound actin filaments, we applied cyclic stretching to fibroblasts treated with Trichostatin A (TSA), which decreases nuclear stiffness and thereby reduces nucleus-binding actin filament tension. TSA-treatment was found to induce more rounded cellular shapes than those of non-treated cells under both static and cyclic stretching conditions. These results suggest that the tension of nucleus-bound actin filaments plays an important role in the formation of elongated fibroblasts under cyclic stretching and that nesprin-1 knockdown causes a decrease of tension in nucleus-associated actin filaments.
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Affiliation(s)
- Naoya Sakamoto
- 1Department of Intelligent Mechanical Systems, Graduate School of System Design, Tokyo Metropolitan University, 6-6 Asahigaoka, Hino, Tokyo 191-0065 Japan
| | - Mai Ogawa
- 2Department of Medical Engineering, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193 Japan
| | - Kiyomi Sadamoto
- 2Department of Medical Engineering, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193 Japan
| | - Masaki Takeuchi
- 2Department of Medical Engineering, Faculty of Health Science and Technology, Kawasaki University of Medical Welfare, 288 Matsushima, Kurashiki, Okayama 701-0193 Japan
| | - Noriyuki Kataoka
- 3Department of Mechanical Engineering, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamuramachi, Koriyama, Fukushima 963-8642 Japan
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319
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Liu L, Luo Q, Sun J, Wang A, Shi Y, Ju Y, Morita Y, Song G. Decreased nuclear stiffness via FAK-ERK1/2 signaling is necessary for osteopontin-promoted migration of bone marrow-derived mesenchymal stem cells. Exp Cell Res 2017; 355:172-181. [PMID: 28392353 DOI: 10.1016/j.yexcr.2017.04.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Revised: 04/01/2017] [Accepted: 04/05/2017] [Indexed: 10/19/2022]
Abstract
Migration of bone marrow-derived mesenchymal stem cells (BMSCs) plays an important role in many physiological and pathological settings, including wound healing. During the migration of BMSCs through interstitial tissues, the movement of the nucleus must be coordinated with the cytoskeletal dynamics, which in turn affects the cell migration efficiency. Our previous study indicated that osteopontin (OPN) significantly promotes the migration of rat BMSCs. However, the nuclear behaviors and involved molecular mechanisms in OPN-mediated BMSC migration are largely unclear. In the present study, using an atomic force microscope (AFM), we found that OPN could decrease the nuclear stiffness of BMSCs and reduce the expression of lamin A/C, which is the main determinant of nuclear stiffness. Increased lamin A/C expression attenuates BMSC migration by increasing nuclear stiffness. Decreased lamin A/C expression promotes BMSC migration by decreasing nuclear stiffness. Furthermore, OPN promotes BMSC migration by diminishing lamin A/C expression and decreasing nuclear stiffness via the FAK-ERK1/2 signaling pathway. This study provides strong evidence for the role of nuclear mechanics in BMSC migration as well as new insight into the molecular mechanisms of OPN-promoted BMSC migration.
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Affiliation(s)
- Lingling Liu
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, People's Republic of China.
| | - Qing Luo
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, People's Republic of China.
| | - Jinghui Sun
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, People's Republic of China.
| | - Aoli Wang
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, People's Republic of China.
| | - Yisong Shi
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, People's Republic of China.
| | - Yang Ju
- Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603, Japan.
| | - Yasuyuki Morita
- Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603, Japan.
| | - Guanbin Song
- Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, People's Republic of China.
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320
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Millon-Frémillon A, Aureille J, Guilluy C. Analyzing Cell Surface Adhesion Remodeling in Response to Mechanical Tension Using Magnetic Beads. J Vis Exp 2017:55330. [PMID: 28362397 PMCID: PMC5408950 DOI: 10.3791/55330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mechanosensitive cell surface adhesion complexes allow cells to sense the mechanical properties of their surroundings. Recent studies have identified both force-sensing molecules at adhesion sites, and force-dependent transcription factors that regulate lineage-specific gene expression and drive phenotypic outputs. However, the signaling networks converting mechanical tension into biochemical pathways have remained elusive. To explore the signaling pathways engaged upon mechanical tension applied to cell surface receptor, superparamagnetic microbeads can be used. Here we present a protocol for using magnetic beads to apply forces to cell surface adhesion proteins. Using this approach, it is possible to investigate not only force-dependent cytoplasmic signaling pathways by various biochemical approaches, but also adhesion remodeling by magnetic isolation of adhesion complexes attached to the ligand-coated beads. This protocol includes the preparation of ligand-coated superparamagnetic beads, and the application of define tensile forces followed by biochemical analyses. Additionally, we provide a representative sample of data demonstrating that tension applied to integrin-based adhesion triggers adhesion remodeling and alters protein tyrosine phosphorylation.
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Affiliation(s)
| | - Julien Aureille
- Institute for Advanced Biosciences, Centre de recherche UGA - INSERM U1209 - CNRS UMR
| | - Christophe Guilluy
- Institute for Advanced Biosciences, Centre de recherche UGA - INSERM U1209 - CNRS UMR;
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321
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Chronopoulos A, Lieberthal TJ, del Río Hernández AE. Pancreatic cancer: a mechanobiology approach. CONVERGENT SCIENCE PHYSICAL ONCOLOGY 2017. [DOI: 10.1088/2057-1739/aa5d1b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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322
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Thorpe SD, Lee DA. Dynamic regulation of nuclear architecture and mechanics-a rheostatic role for the nucleus in tailoring cellular mechanosensitivity. Nucleus 2017; 8:287-300. [PMID: 28152338 PMCID: PMC5499908 DOI: 10.1080/19491034.2017.1285988] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Nuclear architecture, a function of both chromatin and nucleoskeleton structure, is known to change with stem cell differentiation and differs between various somatic cell types. These changes in nuclear architecture are associated with the regulation of gene expression and genome function in a cell-type specific manner. Biophysical stimuli are known effectors of differentiation and also elicit stimuli-specific changes in nuclear architecture. This occurs via the process of mechanotransduction whereby extracellular mechanical forces activate several well characterized signaling cascades of cytoplasmic origin, and potentially some recently elucidated signaling cascades originating in the nucleus. Recent work has demonstrated changes in nuclear mechanics both with pluripotency state in embryonic stem cells, and with differentiation progression in adult mesenchymal stem cells. This review explores the interplay between cytoplasmic and nuclear mechanosensitivity, highlighting a role for the nucleus as a rheostat in tuning the cellular mechano-response.
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Affiliation(s)
- Stephen D Thorpe
- a Institute of Bioengineering, School of Engineering and Materials Science , Queen Mary University of London , London , UK
| | - David A Lee
- a Institute of Bioengineering, School of Engineering and Materials Science , Queen Mary University of London , London , UK
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323
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Mechanotransduction via the nuclear envelope: a distant reflection of the cell surface. Curr Opin Cell Biol 2017; 44:59-67. [DOI: 10.1016/j.ceb.2016.10.003] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2016] [Revised: 10/11/2016] [Accepted: 10/12/2016] [Indexed: 01/08/2023]
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324
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Abstract
Time-lapse, deep-tissue imaging made possible by advances in intravital microscopy has demonstrated the importance of tumour cell migration through confining tracks in vivo. These tracks may either be endogenous features of tissues or be created by tumour or tumour-associated cells. Importantly, migration mechanisms through confining microenvironments are not predicted by 2D migration assays. Engineered in vitro models have been used to delineate the mechanisms of cell motility through confining spaces encountered in vivo. Understanding cancer cell locomotion through physiologically relevant confining tracks could be useful in developing therapeutic strategies to combat metastasis.
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Affiliation(s)
- Colin D Paul
- Department of Chemical and Biomolecular Engineering and the Institute for NanoBioTechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
| | - Panagiotis Mistriotis
- Department of Chemical and Biomolecular Engineering and the Institute for NanoBioTechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
| | - Konstantinos Konstantopoulos
- Department of Chemical and Biomolecular Engineering and the Institute for NanoBioTechnology, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
- Department of Biomedical Engineering, Johns Hopkins University, 3400 North Charles Street, Baltimore, Maryland 21218, USA
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325
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Abstract
As a compartment border, the nuclear envelope (NE) needs to serve as both a protective membrane shell for the genome and a versatile communication interface between the nucleus and the cytoplasm. Despite its important structural role in sheltering the genome, the NE is a dynamic and highly adaptable boundary that changes composition during differentiation, deforms in response to mechanical challenges, can be repaired upon rupture and even rapidly disassembles and reforms during open mitosis. NE remodelling is fundamentally involved in cell growth, division and differentiation, and if perturbed can lead to devastating diseases such as muscular dystrophies or premature ageing.
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326
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Cofilin Regulates Nuclear Architecture through a Myosin-II Dependent Mechanotransduction Module. Sci Rep 2017; 7:40953. [PMID: 28102353 PMCID: PMC5244421 DOI: 10.1038/srep40953] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 12/14/2016] [Indexed: 01/02/2023] Open
Abstract
Structural features of the nucleus including shape, size and deformability impact its function affecting normal cellular processes such as cell differentiation and pathological conditions such as tumor cell migration. Despite the fact that abnormal nuclear morphology has long been a defining characteristic for diseases such as cancer relatively little is known about the mechanisms that control normal nuclear architecture. Mounting evidence suggests close coupling between F-actin cytoskeletal organization and nuclear morphology however, mechanisms regulating this coupling are lacking. Here we identify that Cofilin/ADF-family F-actin remodeling proteins are essential for normal nuclear structure in different cell types. siRNA mediated silencing of Cofilin/ADF provokes striking nuclear defects including aberrant shapes, nuclear lamina disruption and reductions to peripheral heterochromatin. We provide evidence that these anomalies are primarily due to Rho kinase (ROCK) controlled excessive contractile myosin-II activity and not to elevated F-actin polymerization. Furthermore, we demonstrate a requirement for nuclear envelope LINC (linker of nucleoskeleton and cytoskeleton) complex proteins together with lamin A/C for nuclear aberrations induced by Cofilin/ADF loss. Our study elucidates a pivotal regulatory mechanism responsible for normal nuclear structure and which is expected to fundamentally influence nuclear function.
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327
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Samson C, Celli F, Hendriks K, Zinke M, Essawy N, Herrada I, Arteni AA, Theillet FX, Alpha-Bazin B, Armengaud J, Coirault C, Lange A, Zinn-Justin S. Emerin self-assembly mechanism: role of the LEM domain. FEBS J 2017; 284:338-352. [PMID: 27960036 DOI: 10.1111/febs.13983] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 11/18/2016] [Accepted: 12/05/2016] [Indexed: 01/01/2023]
Abstract
At the nuclear envelope, the inner nuclear membrane protein emerin contributes to the interface between the nucleoskeleton and the chromatin. Emerin is an essential actor of the nuclear response to a mechanical signal. Genetic defects in emerin cause Emery-Dreifuss muscular dystrophy. It was proposed that emerin oligomerization regulates nucleoskeleton binding, and impaired oligomerization contributes to the loss of function of emerin disease-causing mutants. We here report the first structural characterization of emerin oligomers. We identified an N-terminal emerin region from amino acid 1 to amino acid 132 that is necessary and sufficient for formation of long curvilinear filaments. In emerin monomer, this region contains a globular LEM domain and a fragment that is intrinsically disordered. Solid-state nuclear magnetic resonance analysis identifies the LEM β-fragment as part of the oligomeric structural core. However, the LEM domain alone does not self-assemble into filaments. Additional residues forming a β-structure are observed within the filaments that could correspond to the unstructured region in emerin monomer. We show that the delK37 mutation causing muscular dystrophy triggers LEM domain unfolding and increases emerin self-assembly rate. Similarly, inserting a disulfide bridge that stabilizes the LEM folded state impairs emerin N-terminal region self-assembly, whereas reducing this disulfide bridge triggers self-assembly. We conclude that the LEM domain, responsible for binding to the chromatin protein BAF, undergoes a conformational change during self-assembly of emerin N-terminal region. The consequences of these structural rearrangement and self-assembly events on emerin binding properties are discussed.
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Affiliation(s)
- Camille Samson
- Laboratory of Structural Biology and Radiobiology, Institute for Integrative Biology of the Cell (CEA, CNRS, University Paris South), University Paris-Saclay, Gif-sur-Yvette, France
| | - Florian Celli
- Laboratory of Structural Biology and Radiobiology, Institute for Integrative Biology of the Cell (CEA, CNRS, University Paris South), University Paris-Saclay, Gif-sur-Yvette, France
| | - Kitty Hendriks
- Department of Molecular Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
| | - Maximilian Zinke
- Department of Molecular Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
| | - Nada Essawy
- Center for Research in Myology (INSERM, CNRS), Université Pierre et Marie Curie Paris 06, Sorbonne Universités, France
| | - Isaline Herrada
- Laboratory of Structural Biology and Radiobiology, Institute for Integrative Biology of the Cell (CEA, CNRS, University Paris South), University Paris-Saclay, Gif-sur-Yvette, France
| | - Ana-Andreea Arteni
- Department of Structural Virology, Institute for Integrative Biology of the Cell (CEA, CNRS, University Paris South), University Paris-Saclay, Gif-sur-Yvette, France
| | - François-Xavier Theillet
- Laboratory of Structural Biology and Radiobiology, Institute for Integrative Biology of the Cell (CEA, CNRS, University Paris South), University Paris-Saclay, Gif-sur-Yvette, France
| | - Béatrice Alpha-Bazin
- Laboratory 'Innovative technologies for Detection and Diagnostics', Institute of Biology and Technology Saclay, CEA, Bagnols-sur-Cèze, France
| | - Jean Armengaud
- Laboratory 'Innovative technologies for Detection and Diagnostics', Institute of Biology and Technology Saclay, CEA, Bagnols-sur-Cèze, France
| | - Catherine Coirault
- Center for Research in Myology (INSERM, CNRS), Université Pierre et Marie Curie Paris 06, Sorbonne Universités, France
| | - Adam Lange
- Department of Molecular Biophysics, Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany.,Institut für Biologie, Humboldt-Universität zu Berlin, Germany
| | - Sophie Zinn-Justin
- Laboratory of Structural Biology and Radiobiology, Institute for Integrative Biology of the Cell (CEA, CNRS, University Paris South), University Paris-Saclay, Gif-sur-Yvette, France
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328
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Abstract
The regulation of nuclear shape and deformability is a key factor in controlling diverse events from embryonic development to cancer cell metastasis, but the mechanisms governing this process are still unclear. Our recent study demonstrated an unexpected role for the F-actin bundling protein fascin in controlling nuclear plasticity through a direct interaction with Nesprin-2. Nesprin-2 is a component of the LINC complex that is known to couple the F-actin cytoskeleton to the nuclear envelope. We demonstrated that fascin, which is predominantly associated with peripheral F-actin rich filopodia, binds directly to Nesprin-2 at the nuclear envelope in a range of cell types. Depleting fascin or specifically blocking the fascin-Nesprin-2 complex leads to defects in nuclear polarization, movement and cell invasion. These studies reveal a novel role for an F-actin bundling protein in control of nuclear plasticity and underline the importance of defining nuclear-associated roles for F-actin binding proteins in future.
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Affiliation(s)
- Karin Pfisterer
- a Randall Division of Cell and Molecular Biophysics , King's College London, New Hunts House , Guys Campus, London , UK
| | - Asier Jayo
- a Randall Division of Cell and Molecular Biophysics , King's College London, New Hunts House , Guys Campus, London , UK.,b Department of Basic Sciences , Physiology Unit, San Pablo CEU University , Monteprincipe Campus, Madrid , Spain
| | - Maddy Parsons
- a Randall Division of Cell and Molecular Biophysics , King's College London, New Hunts House , Guys Campus, London , UK
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329
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Stephens AD, Banigan EJ, Adam SA, Goldman RD, Marko JF. Chromatin and lamin A determine two different mechanical response regimes of the cell nucleus. Mol Biol Cell 2017; 28:1984-1996. [PMID: 28057760 PMCID: PMC5541848 DOI: 10.1091/mbc.e16-09-0653] [Citation(s) in RCA: 286] [Impact Index Per Article: 40.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 11/04/2016] [Accepted: 12/29/2016] [Indexed: 02/02/2023] Open
Abstract
The cell nucleus must continually resist and respond to intercellular and intracellular mechanical forces to transduce mechanical signals and maintain proper genome organization and expression. Altered nuclear mechanics is associated with many human diseases, including heart disease, progeria, and cancer. Chromatin and nuclear envelope A-type lamin proteins are known to be key nuclear mechanical components perturbed in these diseases, but their distinct mechanical contributions are not known. Here we directly establish the separate roles of chromatin and lamin A/C and show that they determine two distinct mechanical regimes via micromanipulation of single isolated nuclei. Chromatin governs response to small extensions (<3 μm), and euchromatin/heterochromatin levels modulate the stiffness. In contrast, lamin A/C levels control nuclear strain stiffening at large extensions. These results can be understood through simulations of a polymeric shell and cross-linked polymer interior. Our results provide a framework for understanding the differential effects of chromatin and lamin A/C in cell nuclear mechanics and their alterations in disease.
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Affiliation(s)
- Andrew D Stephens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Edward J Banigan
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
| | - Stephen A Adam
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
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330
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Cho S, Irianto J, Discher DE. Mechanosensing by the nucleus: From pathways to scaling relationships. J Cell Biol 2017; 216:305-315. [PMID: 28043971 PMCID: PMC5294790 DOI: 10.1083/jcb.201610042] [Citation(s) in RCA: 238] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 12/05/2016] [Accepted: 12/14/2016] [Indexed: 01/01/2023] Open
Abstract
Cho, Irianto, and Discher review emerging mechanisms of nuclear mechanosensing and propose through meta-analyses of published data the universality of mechanosensing pathways. The nucleus is linked mechanically to the extracellular matrix via multiple polymers that transmit forces to the nuclear envelope and into the nuclear interior. Here, we review some of the emerging mechanisms of nuclear mechanosensing, which range from changes in protein conformation and transcription factor localization to chromosome reorganization and membrane dilation up to rupture. Nuclear mechanosensing encompasses biophysically complex pathways that often converge on the main structural proteins of the nucleus, the lamins. We also perform meta-analyses of public transcriptomics and proteomics data, which indicate that some of the mechanosensing pathways relaying signals from the collagen matrix to the nucleus apply to a broad range of species, tissues, and diseases.
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Affiliation(s)
- Sangkyun Cho
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
| | - Jerome Irianto
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
| | - Dennis E Discher
- Molecular and Cell Biophysics Lab, University of Pennsylvania, Philadelphia, PA 19104
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331
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Kamm RD, Lammerding J, Mofrad MRK. Cellular Nanomechanics. SPRINGER HANDBOOK OF NANOTECHNOLOGY 2017. [DOI: 10.1007/978-3-662-54357-3_31] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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332
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Miroshnikova YA, Nava MM, Wickström SA. Emerging roles of mechanical forces in chromatin regulation. J Cell Sci 2017. [DOI: 10.1242/jcs.202192] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
ABSTRACT
Cells are constantly subjected to a spectrum of mechanical cues, such as shear stress, compression, differential tissue rigidity and strain, to which they adapt by engaging mechanisms of mechanotransduction. While the central role of cell adhesion receptors in this process is established, it has only recently been appreciated that mechanical cues reach far beyond the plasma membrane and the cytoskeleton, and are directly transmitted to the nucleus. Furthermore, changes in the mechanical properties of the perinuclear cytoskeleton, nuclear lamina and chromatin are critical for cellular responses and adaptation to external mechanical cues. In that respect, dynamic changes in the nuclear lamina and the surrounding cytoskeleton modify mechanical properties of the nucleus, thereby protecting genetic material from damage. The importance of this mechanism is highlighted by debilitating genetic diseases, termed laminopathies, that result from impaired mechanoresistance of the nuclear lamina. What has been less evident, and represents one of the exciting emerging concepts, is that chromatin itself is an active rheological element of the nucleus, which undergoes dynamic changes upon application of force, thereby facilitating cellular adaption to differential force environments. This Review aims to highlight these emerging concepts by discussing the latest literature in this area and by proposing an integrative model of cytoskeletal and chromatin-mediated responses to mechanical stress.
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Affiliation(s)
| | - Michele M. Nava
- Paul Gerson Unna Group ‘Skin Homeostasis and Ageing’, Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
| | - Sara A. Wickström
- Paul Gerson Unna Group ‘Skin Homeostasis and Ageing’, Max Planck Institute for Biology of Ageing, Cologne 50931, Germany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne 50931, Germany
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333
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Iyer SR, Shah SB, Valencia AP, Schneider MF, Hernández-Ochoa EO, Stains JP, Blemker SS, Lovering RM. Altered nuclear dynamics in MDX myofibers. J Appl Physiol (1985) 2016; 122:470-481. [PMID: 27979987 DOI: 10.1152/japplphysiol.00857.2016] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Revised: 12/02/2016] [Accepted: 12/06/2016] [Indexed: 01/17/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a genetic disorder in which the absence of dystrophin leads to progressive muscle degeneration and weakness. Although the genetic basis is known, the pathophysiology of dystrophic skeletal muscle remains unclear. We examined nuclear movement in wild-type (WT) and muscular dystrophy mouse model for DMD (MDX) (dystrophin-null) mouse myofibers. We also examined expression of proteins in the linkers of nucleoskeleton and cytoskeleton (LINC) complex, as well as nuclear transcriptional activity via histone H3 acetylation and polyadenylate-binding nuclear protein-1. Because movement of nuclei is not only LINC dependent but also microtubule dependent, we analyzed microtubule density and organization in WT and MDX myofibers, including the application of a unique 3D tool to assess microtubule core structure. Nuclei in MDX myofibers were more mobile than in WT myofibers for both distance traveled and velocity. MDX muscle shows reduced expression and labeling intensity of nesprin-1, a LINC protein that attaches the nucleus to the microtubule and actin cytoskeleton. MDX nuclei also showed altered transcriptional activity. Previous studies established that microtubule structure at the cortex is disrupted in MDX myofibers; our analyses extend these findings by showing that microtubule structure in the core is also disrupted. In addition, we studied malformed MDX myofibers to better understand the role of altered myofiber morphology vs. microtubule architecture in the underlying susceptibility to injury seen in dystrophic muscles. We incorporated morphological and microtubule architectural concepts into a simplified finite element mathematical model of myofiber mechanics, which suggests a greater contribution of myofiber morphology than microtubule structure to muscle biomechanical performance.NEW & NOTEWORTHY Microtubules provide the means for nuclear movement but show altered organization in the muscular dystrophy mouse model (MDX) (dystrophin-null) muscle. Here, MDX myofibers show increased nuclear movement, altered transcriptional activity, and altered linkers of nucleoskeleton and cytoskeleton complex expression compared with healthy myofibers. Microtubule architecture was incorporated in finite element modeling of passive stretch, revealing a role of fiber malformation, commonly found in MDX muscle. The results suggest that alterations in microtubule architecture in MDX muscle affect nuclear movement, which is essential for muscle function.
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Affiliation(s)
- Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Sameer B Shah
- Departments of Orthopaedic Surgery and Bioengineering, University of California San Diego, La Jolla, California
| | - Ana P Valencia
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Joseph P Stains
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Silvia S Blemker
- Department of Biomedical Engineering and Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia; and
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland; .,Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
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334
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Szczesny SE, Driscoll TP, Tseng HY, Liu PC, Heo SJ, Mauck RL, Chao PHG. Crimped Nanofibrous Biomaterials Mimic Microstructure and Mechanics of Native Tissue and Alter Strain Transfer to Cells. ACS Biomater Sci Eng 2016; 3:2869-2876. [PMID: 29147681 DOI: 10.1021/acsbiomaterials.6b00646] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
To fully recapitulate tissue microstructure and mechanics, fiber crimping must exist within biomaterials used for tendon/ligament engineering. Existing crimped nanofibrous scaffolds produced via electrospinning are dense materials that prevent cellular infiltration into the scaffold interior. In this study, we used a sacrificial fiber population to increase the scaffold porosity and evaluated the effect on fiber crimping. We found that increasing scaffold porosity increased fiber crimping and ensured that the fibers properly uncrimped as the scaffolds were stretched by minimizing fiber-fiber interactions. Constitutive modeling demonstrated that the fiber uncrimping produced a nonlinear mechanical behavior similar to that of native tendon and ligament. Interestingly, fiber crimping altered strain transmission to the nuclei of cells seeded on the scaffolds, which may account for previously observed changes in gene expression. These crimped biomaterials are useful for developing functional fiber-reinforced tissues and for studying the effects of altered fiber crimping due to damage or degeneration.
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Affiliation(s)
- Spencer E Szczesny
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States
| | - Tristan P Driscoll
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Hsiao-Yun Tseng
- Institute of Biomedical Engineering, School of Medicine and School of Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Pang-Ching Liu
- Institute of Biomedical Engineering, School of Medicine and School of Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Su-Jin Heo
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Robert L Mauck
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, Philadelphia, Pennsylvania 19104, United States.,Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Pen-Hsiu G Chao
- Institute of Biomedical Engineering, School of Medicine and School of Engineering, National Taiwan University, Taipei 10617, Taiwan
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335
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Tajik A, Zhang Y, Wei F, Sun J, Jia Q, Zhou W, Singh R, Khanna N, Belmont AS, Wang N. Transcription upregulation via force-induced direct stretching of chromatin. NATURE MATERIALS 2016; 15:1287-1296. [PMID: 27548707 PMCID: PMC5121013 DOI: 10.1038/nmat4729] [Citation(s) in RCA: 380] [Impact Index Per Article: 47.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 07/14/2016] [Indexed: 05/02/2023]
Abstract
Mechanical forces play critical roles in the function of living cells. However, the underlying mechanisms of how forces influence nuclear events remain elusive. Here, we show that chromatin deformation as well as force-induced transcription of a green fluorescent protein (GFP)-tagged bacterial-chromosome dihydrofolate reductase (DHFR) transgene can be visualized in a living cell by using three-dimensional magnetic twisting cytometry to apply local stresses on the cell surface via an Arg-Gly-Asp-coated magnetic bead. Chromatin stretching depended on loading direction. DHFR transcription upregulation was sensitive to load direction and proportional to the magnitude of chromatin stretching. Disrupting filamentous actin or inhibiting actomyosin contraction abrogated or attenuated force-induced DHFR transcription, whereas activating endogenous contraction upregulated force-induced DHFR transcription. Our findings suggest that local stresses applied to integrins propagate from the tensed actin cytoskeleton to the LINC complex and then through lamina-chromatin interactions to directly stretch chromatin and upregulate transcription.
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Affiliation(s)
- Arash Tajik
- Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 China
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - Yuejin Zhang
- Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 China
| | - Fuxiang Wei
- Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 China
| | - Jian Sun
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - Qiong Jia
- Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 China
| | - Wenwen Zhou
- Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 China
| | - Rishi Singh
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - Nimish Khanna
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
| | - Andrew S. Belmont
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
- Send correspondence to: Dr. Ning Wang at or Dr. Andrew Belmont at
| | - Ning Wang
- Department of Biomedical Engineering, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074 China
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801 USA
- Send correspondence to: Dr. Ning Wang at or Dr. Andrew Belmont at
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336
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The mammalian LINC complex regulates genome transcriptional responses to substrate rigidity. Sci Rep 2016; 6:38063. [PMID: 27905489 PMCID: PMC5131312 DOI: 10.1038/srep38063] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Accepted: 11/03/2016] [Indexed: 12/14/2022] Open
Abstract
Mechanical integration of the nucleus with the extracellular matrix (ECM) is established by linkage between the cytoskeleton and the nucleus. This integration is hypothesized to mediate sensing of ECM rigidity, but parsing the function of nucleus-cytoskeleton linkage from other mechanisms has remained a central challenge. Here we took advantage of the fact that the LINC (linker of nucleoskeleton and cytoskeleton) complex is a known molecular linker of the nucleus to the cytoskeleton, and asked how it regulates the sensitivity of genome-wide transcription to substratum rigidity. We show that gene mechanosensitivity is preserved after LINC disruption, but reversed in direction. Combined with myosin inhibition studies, we identify genes that depend on nuclear tension for their regulation. We also show that LINC disruption does not attenuate nuclear shape sensitivity to substrate rigidity. Our results show for the first time that the LINC complex facilitates mechano-regulation of expression across the genome.
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337
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Heo SJ, Driscoll TP, Thorpe SD, Nerurkar NL, Baker BM, Yang MT, Chen CS, Lee DA, Mauck RL. Differentiation alters stem cell nuclear architecture, mechanics, and mechano-sensitivity. eLife 2016; 5. [PMID: 27901466 PMCID: PMC5148611 DOI: 10.7554/elife.18207] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 11/29/2016] [Indexed: 12/13/2022] Open
Abstract
Mesenchymal stem cell (MSC) differentiation is mediated by soluble and physical cues. In this study, we investigated differentiation-induced transformations in MSC cellular and nuclear biophysical properties and queried their role in mechanosensation. Our data show that nuclei in differentiated bovine and human MSCs stiffen and become resistant to deformation. This attenuated nuclear deformation was governed by restructuring of Lamin A/C and increased heterochromatin content. This change in nuclear stiffness sensitized MSCs to mechanical-loading-induced calcium signaling and differentiated marker expression. This sensitization was reversed when the 'stiff' differentiated nucleus was softened and was enhanced when the 'soft' undifferentiated nucleus was stiffened through pharmacologic treatment. Interestingly, dynamic loading of undifferentiated MSCs, in the absence of soluble differentiation factors, stiffened and condensed the nucleus, and increased mechanosensitivity more rapidly than soluble factors. These data suggest that the nucleus acts as a mechanostat to modulate cellular mechanosensation during differentiation.
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Affiliation(s)
- Su-Jin Heo
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States.,Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Pennsylvania, United States
| | - Tristan P Driscoll
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States.,Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Pennsylvania, United States
| | - Stephen D Thorpe
- Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
| | - Nandan L Nerurkar
- Department of Genetics, Harvard Medical School, Harvard University, Boston, United States
| | - Brendon M Baker
- Department of Biomedical Engineering, College of Engineering, Boston University, Boston, United States.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, United States
| | - Michael T Yang
- Department of Biomedical Engineering, College of Engineering, Boston University, Boston, United States
| | - Christopher S Chen
- Department of Biomedical Engineering, College of Engineering, Boston University, Boston, United States.,Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, United States
| | - David A Lee
- Institute of Bioengineering, School of Engineering and Materials Science, Queen Mary University of London, London, United Kingdom
| | - Robert L Mauck
- McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, United States.,Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Pennsylvania, United States
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338
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Kirby TJ, Lammerding J. Cell mechanotransduction: Stretch to express. NATURE MATERIALS 2016; 15:1227-1229. [PMID: 27876751 DOI: 10.1038/nmat4809] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Affiliation(s)
- Tyler J Kirby
- Weill Institute for Cell and Molecular Biology and the Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
| | - Jan Lammerding
- Weill Institute for Cell and Molecular Biology and the Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York, USA
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339
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Porter LJ, Holt MR, Soong D, Shanahan CM, Warren DT. Prelamin A Accumulation Attenuates Rac1 Activity and Increases the Intrinsic Migrational Persistence of Aged Vascular Smooth Muscle Cells. Cells 2016; 5:E41. [PMID: 27854297 PMCID: PMC5187525 DOI: 10.3390/cells5040041] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 11/10/2016] [Accepted: 11/11/2016] [Indexed: 02/01/2023] Open
Abstract
Vascular smooth muscle cell (VSMC) motility is essential during both physiological and pathological vessel remodeling. Although ageing has emerged as a major risk factor in the development of cardiovascular disease, our understanding of the impact of ageing on VSMC motility remains limited. Prelamin A accumulation is known to drive VSMC ageing and we show that presenescent VSMCs, that have accumulated prelamin A, display increased focal adhesion dynamics, augmented migrational velocity/persistence and attenuated Rac1 activity. Importantly, prelamin A accumulation in proliferative VSMCs, induced by depletion of the prelamin A processing enzyme FACE1, recapitulated the focal adhesion, migrational persistence and Rac1 phenotypes observed in presenescent VSMCs. Moreover, lamin A/C-depleted VSMCs also display reduced Rac1 activity, suggesting that prelamin A influences Rac1 activity by interfering with lamin A/C function at the nuclear envelope. Taken together, these data demonstrate that lamin A/C maintains Rac1 activity in VSMCs and prelamin A disrupts lamin A/C function to reduce Rac1 activity and induce migrational persistence during VSMC ageing.
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Affiliation(s)
- Lauren J Porter
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College London, London SE5 9NU, UK.
| | - Mark R Holt
- Randall Division of Cell and Molecular Biophysics, New Hunt's House, King's College London, London SE1 1UL, UK.
| | - Daniel Soong
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College London, London SE5 9NU, UK.
- MRC Centre for Reproductive Health, Queen's Medical Research Institute, University of Edinburgh, Edinburgh EH16 4TJ, UK.
| | - Catherine M Shanahan
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College London, London SE5 9NU, UK.
| | - Derek T Warren
- British Heart Foundation Centre of Research Excellence, Cardiovascular Division, King's College London, London SE5 9NU, UK.
- School of Pharmacy, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
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340
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Kumar A, Shivashankar GV. Dynamic interaction between actin and nesprin2 maintain the cell nucleus in a prestressed state. Methods Appl Fluoresc 2016; 4:044008. [DOI: 10.1088/2050-6120/4/4/044008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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341
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The Cell Nucleus Serves as a Mechanotransducer of Tissue Damage-Induced Inflammation. Cell 2016; 165:1160-1170. [PMID: 27203112 DOI: 10.1016/j.cell.2016.04.016] [Citation(s) in RCA: 144] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 02/18/2016] [Accepted: 04/01/2016] [Indexed: 01/14/2023]
Abstract
Tissue damage activates cytosolic phospholipase A2 (cPLA2), releasing arachidonic acid (AA), which is oxidized to proinflammatory eicosanoids by 5-lipoxygenase (5-LOX) on the nuclear envelope. How tissue damage is sensed to activate cPLA2 is unknown. We investigated this by live imaging in wounded zebrafish larvae, where damage of the fin tissue causes osmotic cell swelling at the wound margin and the generation of a chemotactic eicosanoid signal. Osmotic swelling of cells and their nuclei activates cPla2 by translocating it from the nucleoplasm to the nuclear envelope. Elevated cytosolic Ca(2+) was necessary but not sufficient for cPla2 translocation, and nuclear swelling was required in parallel. cPla2 translocation upon nuclear swelling was reconstituted in isolated nuclei and appears to be a simple physical process mediated by tension in the nuclear envelope. Our data suggest that the nucleus plays a mechanosensory role in inflammation by transducing cell swelling and lysis into proinflammatory eicosanoid signaling.
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342
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Sun Z, Guo SS, Fässler R. Integrin-mediated mechanotransduction. J Cell Biol 2016; 215:445-456. [PMID: 27872252 PMCID: PMC5119943 DOI: 10.1083/jcb.201609037] [Citation(s) in RCA: 621] [Impact Index Per Article: 77.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Revised: 10/26/2016] [Accepted: 10/27/2016] [Indexed: 12/16/2022] Open
Abstract
Sun, Guo, and Fässler review the function and regulation of integrin-mediated mechanotransduction and discuss how its dysregulation impacts cancer progession. Cells can detect and react to the biophysical properties of the extracellular environment through integrin-based adhesion sites and adapt to the extracellular milieu in a process called mechanotransduction. At these adhesion sites, integrins connect the extracellular matrix (ECM) with the F-actin cytoskeleton and transduce mechanical forces generated by the actin retrograde flow and myosin II to the ECM through mechanosensitive focal adhesion proteins that are collectively termed the “molecular clutch.” The transmission of forces across integrin-based adhesions establishes a mechanical reciprocity between the viscoelasticity of the ECM and the cellular tension. During mechanotransduction, force allosterically alters the functions of mechanosensitive proteins within adhesions to elicit biochemical signals that regulate both rapid responses in cellular mechanics and long-term changes in gene expression. Integrin-mediated mechanotransduction plays important roles in development and tissue homeostasis, and its dysregulation is often associated with diseases.
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Affiliation(s)
- Zhiqi Sun
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Shengzhen S Guo
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Reinhard Fässler
- Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
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343
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Abstract
Eicosanoid signaling plays key pro-inflammatory roles during tissue damage. Now, Enyedi et al. show that swelling of nuclei in cell corpses activates eicosanoid signaling to recruit leukocytes to sites of tissue damage. The enhanced membrane tension in swollen nuclei directly promotes calcium-dependent translocation and activation of enzymes involved in eicosanoid biosynthesis.
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Affiliation(s)
- Wakam Chang
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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344
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Mak M, Spill F, Kamm RD, Zaman MH. Single-Cell Migration in Complex Microenvironments: Mechanics and Signaling Dynamics. J Biomech Eng 2016; 138:021004. [PMID: 26639083 DOI: 10.1115/1.4032188] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Indexed: 12/21/2022]
Abstract
Cells are highly dynamic and mechanical automata powered by molecular motors that respond to external cues. Intracellular signaling pathways, either chemical or mechanical, can be activated and spatially coordinated to induce polarized cell states and directional migration. Physiologically, cells navigate through complex microenvironments, typically in three-dimensional (3D) fibrillar networks. In diseases, such as metastatic cancer, they invade across physiological barriers and remodel their local environments through force, matrix degradation, synthesis, and reorganization. Important external factors such as dimensionality, confinement, topographical cues, stiffness, and flow impact the behavior of migrating cells and can each regulate motility. Here, we review recent progress in our understanding of single-cell migration in complex microenvironments.
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345
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Wagner AP, Chinnathambi S, Titze IR, Sander EA. Vibratory stimulation enhances thyroid epithelial cell function. Biochem Biophys Rep 2016; 8:376-381. [PMID: 28955979 PMCID: PMC5614476 DOI: 10.1016/j.bbrep.2016.10.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 10/11/2016] [Accepted: 10/13/2016] [Indexed: 02/06/2023] Open
Abstract
The tissues of the body are routinely subjected to various forms of mechanical vibration, the frequency, amplitude, and duration of which can contribute both positively and negatively to human health. The vocal cords, which are in close proximity to the thyroid, may also supply the thyroid with important mechanical signals that modulate hormone production via mechanical vibrations from phonation. In order to explore the possibility that vibrational stimulation from vocalization can enhance thyroid epithelial cell function, FRTL-5 rat thyroid cells were subjected to either chemical stimulation with thyroid stimulating hormone (TSH), mechanical stimulation with physiological vibrations, or a combination of the two, all in a well-characterized, torsional rheometer-bioreactor. The FRTL-5 cells responded to mechanical stimulation with significantly (p<0.05) increased metabolic activity, significantly (p<0.05) increased ROS production, and increased gene expression of thyroglobulin and sodium-iodide symporter compared to un-stimulated controls, and showed an equivalent or greater response than TSH only stimulated cells. Furthermore, the combination of TSH and oscillatory motion produced a greater response than mechanical or chemical stimulation alone. Taken together, these results suggest that mechanical vibrations could provide stimulatory cues that help maintain thyroid function. Thyroid epithelial cells responded to mechanical vibrations similar to those from vocalization. This response was equivalent or greater compared to chemical stimulation. The combination of mechanical and chemical stimulation was synergistic. It may be possible to influence thyroid function with mechanical vibrations.
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Affiliation(s)
- A P Wagner
- Department of Biomedical Engineering, University of Iowa, IA, USA
| | - S Chinnathambi
- Department of Biomedical Engineering, University of Iowa, IA, USA
| | - I R Titze
- Department of Communication Sciences and Disorders, University of Iowa, IA, USA.,National Center for Voice and Speech, University of Utah, Salt Lake City, UT, USA
| | - E A Sander
- Department of Biomedical Engineering, University of Iowa, IA, USA
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346
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Abstract
Lamins are major components of the nuclear lamina, a network of proteins that supports the nuclear envelope in metazoan cells. Over the past decade, biochemical studies have provided support for the view that lamins are not passive bystanders providing mechanical stability to the nucleus but play an active role in the organization of the genome and the function of fundamental nuclear processes. It has also become apparent that lamins are critical for human health, as a large number of mutations identified in the gene that encodes for A-type lamins are associated with tissue-specific and systemic genetic diseases, including the accelerated aging disorder known as Hutchinson-Gilford progeria syndrome. Recent years have witnessed great advances in our understanding of the role of lamins in the nucleus and the functional consequences of disease-associated A-type lamin mutations. Many of these findings have been presented in comprehensive reviews. In this mini-review, we discuss recent breakthroughs in the role of lamins in health and disease and what lies ahead in lamin research.
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Affiliation(s)
- Sita Reddy
- Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Lucio Comai
- Department of Biochemistry and Molecular Biology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA; Department of Molecular Microbiology and Immunology, Institute for Genetic Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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347
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Arsenovic PT, Ramachandran I, Bathula K, Zhu R, Narang JD, Noll NA, Lemmon CA, Gundersen GG, Conway DE. Nesprin-2G, a Component of the Nuclear LINC Complex, Is Subject to Myosin-Dependent Tension. Biophys J 2016; 110:34-43. [PMID: 26745407 DOI: 10.1016/j.bpj.2015.11.014] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 11/11/2015] [Accepted: 11/12/2015] [Indexed: 01/14/2023] Open
Abstract
The nucleus of a cell has long been considered to be subject to mechanical force. Despite the observation that mechanical forces affect nuclear geometry and movement, how forces are applied onto the nucleus is not well understood. The nuclear LINC (linker of nucleoskeleton and cytoskeleton) complex has been hypothesized to be the critical structure that mediates the transfer of mechanical forces from the cytoskeleton onto the nucleus. Previously used techniques for studying nuclear forces have been unable to resolve forces across individual proteins, making it difficult to clearly establish if the LINC complex experiences mechanical load. To directly measure forces across the LINC complex, we generated a fluorescence resonance energy transfer-based tension biosensor for nesprin-2G, a key structural protein in the LINC complex, which physically links this complex to the actin cytoskeleton. Using this sensor we show that nesprin-2G is subject to mechanical tension in adherent fibroblasts, with highest levels of force on the apical and equatorial planes of the nucleus. We also show that the forces across nesprin-2G are dependent on actomyosin contractility and cell elongation. Additionally, nesprin-2G tension is reduced in fibroblasts from Hutchinson-Gilford progeria syndrome patients. This report provides the first, to our knowledge, direct evidence that nesprin-2G, and by extension the LINC complex, is subject to mechanical force. We also present evidence that nesprin-2G localization to the nuclear membrane is altered under high-force conditions. Because forces across the LINC complex are altered by a variety of different conditions, mechanical forces across the LINC complex, as well as the nucleus in general, may represent an important mechanism for mediating mechanotransduction.
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Affiliation(s)
- Paul T Arsenovic
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Iswarya Ramachandran
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Kranthidhar Bathula
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Ruijun Zhu
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Jiten D Narang
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Natalie A Noll
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Christopher A Lemmon
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia
| | - Gregg G Gundersen
- Department of Pathology and Cell Biology, Columbia University, New York, New York
| | - Daniel E Conway
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, Virginia.
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348
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Wang S, Volk T. Composite biopolymer scaffolds shape muscle nucleus: Insights and perspectives from Drosophila. BIOARCHITECTURE 2016; 5:35-43. [PMID: 26605802 DOI: 10.1080/19490992.2015.1106061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Contractile muscle fibers produce enormous intrinsic forces during contraction/relaxation waves. These forces are directly applied to their cytoplasmic organelles including mitochondria, sarcoplasmic reticulum, and multiple nuclei. Data from our analysis of Drosophila larval somatic muscle fibers suggest that an intricate network of organized microtubules (MT) intermingled with Spectrin-Repeat-Containing Proteins (SRCPs) are major structural elements that protect muscle organelles and maintain their structure and position during muscle contraction. Whereas the perinuclear MT network provides structural rigidity to the myonucleus, the SRCPs Nesprin and Spectraplakin form semiflexible filamentous biopolymer networks, providing nuclei with the elasticity required to resist the contractile cytoplasmic forces produced by the muscle. Spectrin repeats are domains found in numerous structural proteins, which are able to unfold under tension and are subject to mechanical stresses in the cell. This unique composite scaffold combines rigidity and resilience in order to neutralize the oscillating cellular forces occurring during muscle contraction/relaxation waves and thereby protect myonuclei. We suggest that the elastic properties of SRCPs are critical for nuclear protection and proper function in muscle fibers.
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Affiliation(s)
- Shuoshuo Wang
- a Department of Molecular Genetics ; Weizmann Institute of Science ; Rehovot , Israel
| | - Talila Volk
- a Department of Molecular Genetics ; Weizmann Institute of Science ; Rehovot , Israel
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349
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Meier I. LINCing the eukaryotic tree of life - towards a broad evolutionary comparison of nucleocytoplasmic bridging complexes. J Cell Sci 2016; 129:3523-3531. [PMID: 27591260 DOI: 10.1242/jcs.186700] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The nuclear envelope is much more than a simple barrier between nucleoplasm and cytoplasm. Nuclear envelope bridging complexes are protein complexes spanning both the inner and outer nuclear envelope membranes, thus directly connecting the cytoplasm with the nucleoplasm. In metazoans, they are involved in connecting the cytoskeleton with the nucleoskeleton, and act as anchoring platforms at the nuclear envelope for the positioning and moving of both nuclei and chromosomes. Recently, nucleocytoplasmic bridging complexes have also been identified in more evolutionarily diverse organisms, including land plants. Here, I discuss similarities and differences among and between eukaryotic supergroups, specifically of the proteins forming the cytoplasmic surface of these complexes. I am proposing a structure and function for a hypothetical ancestral nucleocytoplasmic bridging complex in the last eukaryotic common ancestor, with the goal to stimulate research in more diverse emerging model organisms.
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Affiliation(s)
- Iris Meier
- Department of Molecular Genetics and Center for RNA Biology, The Ohio State University, 520 Aronoff Laboratory, 318 W 12th Avenue, Columbus, OH 43210, USA
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350
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Mino A, Troeger A, Brendel C, Cantor A, Harris C, Ciuculescu MF, Williams DA. RhoH participates in a multi-protein complex with the zinc finger protein kaiso that regulates both cytoskeletal structures and chemokine-induced T cells. Small GTPases 2016; 9:260-273. [PMID: 27574848 DOI: 10.1080/21541248.2016.1220780] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
RhoH is a haematopoietic -specific, GTPase-deficient Rho GTPase that plays an essential role in T lymphocyte development and haematopoietic cell migration. RhoH is known to interact with ZAP70 in T cell receptor (TCR) signaling and antagonize Rac GTPase activity. To further elucidate the molecular mechanisms of RhoH in T cell function, we carried out in vivo biotinylation and mass spectrometry analysis to identify new RhoH-interacting proteins in Jurkat T cells. We indentified Kaiso by streptavidin capture and confirmed the interaction with RhoH by co-immunoprecipitation. Kaiso is a 95 kDa dual-specific Broad complex, Trantrak, Bric-a-brac/Pox virus, Zinc finger (POZ-ZF) transcription factor that has been shown to regulate both gene expression and p120 catenin-associated cell-cell adhesions. We further showed that RhoH, Kaiso and p120 catenin all co-localize at chemokine-induced actin-containing cell protrusion sites. Using RhoH knockdown we demonstrated that Kaiso localization depends on RhoH function. Similar to the effect of RhoH deficiency, Kaiso down-regulation led to altered cell migration and actin-polymerization in chemokine stimulated Jurkat cells. Interestingly, RhoH and Kaiso also co-localized to the nucleus in a time-dependent fashion after chemokine stimulation and with T cell receptor activation where RhoH is required for Kaiso localization. Based on these results and previous studies, we propose that extracellular microenvironment signals regulate RhoH and Kaiso to modulate actin-cytoskeleton structure and transcriptional activity during T cell migration.
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Affiliation(s)
- Akihisa Mino
- a Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Harvard Medical School , Boston , MA , USA
| | - Anja Troeger
- b Department of Pediatric Hematology , Oncology and Stem Cell Transplantation, University Hospital Regensburg , Regensburg , Germany
| | - Christian Brendel
- a Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Harvard Medical School , Boston , MA , USA
| | - Alan Cantor
- a Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Harvard Medical School , Boston , MA , USA
| | - Chad Harris
- a Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Harvard Medical School , Boston , MA , USA
| | - Marioara F Ciuculescu
- a Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Harvard Medical School , Boston , MA , USA
| | - David A Williams
- a Division of Hematology/Oncology, Boston Children's Hospital and the Dana-Farber Cancer Institute, Harvard Medical School , Boston , MA , USA
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