1
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Kechagia Z, Eibauer M, Medalia O. Structural determinants of intermediate filament mechanics. Curr Opin Cell Biol 2024; 89:102375. [PMID: 38850681 DOI: 10.1016/j.ceb.2024.102375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Revised: 04/26/2024] [Accepted: 05/03/2024] [Indexed: 06/10/2024]
Abstract
Intermediate filaments (IFs) are integral to the cell cytoskeleton, supporting cellular mechanical stability. Unlike other cytoskeletal components, the detailed structure of assembled IFs has yet to be resolved. This review highlights new insights, linking the complex IF hierarchical assembly to their mechanical properties and impact on cellular functions. While we focus on vimentin IFs, we draw comparisons to keratins, showcasing the distinctive structural and mechanical features that underlie their unique mechanical responses.
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Affiliation(s)
- Zanetta Kechagia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
| | - Matthias Eibauer
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Ohad Medalia
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland.
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2
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Jakob R, Britt BR, Giampietro C, Mazza E, Ehret AE. Discrete network models of endothelial cells and their interactions with the substrate. Biomech Model Mechanobiol 2024; 23:941-957. [PMID: 38351427 PMCID: PMC11101350 DOI: 10.1007/s10237-023-01815-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 12/30/2023] [Indexed: 05/18/2024]
Abstract
Endothelial cell monolayers line the inner surfaces of blood and lymphatic vessels. They are continuously exposed to different mechanical loads, which may trigger mechanobiological signals and hence play a role in both physiological and pathological processes. Computer-based mechanical models of cells contribute to a better understanding of the relation between cell-scale loads and cues and the mechanical state of the hosting tissue. However, the confluency of the endothelial monolayer complicates these approaches since the intercellular cross-talk needs to be accounted for in addition to the cytoskeletal mechanics of the individual cells themselves. As a consequence, the computational approach must be able to efficiently model a large number of cells and their interaction. Here, we simulate cytoskeletal mechanics by means of molecular dynamics software, generally suitable to deal with large, locally interacting systems. Methods were developed to generate models of single cells and large monolayers with hundreds of cells. The single-cell model was considered for a comparison with experimental data. To this end, we simulated cell interactions with a continuous, deformable substrate, and computationally replicated multistep traction force microscopy experiments on endothelial cells. The results indicate that cell discrete network models are able to capture relevant features of the mechanical behaviour and are thus well-suited to investigate the mechanics of the large cytoskeletal network of individual cells and cell monolayers.
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Affiliation(s)
- Raphael Jakob
- Institute for Mechanical Systems, ETH Zurich, CH-8092, Zürich, Switzerland
| | - Ben R Britt
- Institute for Mechanical Systems, ETH Zurich, CH-8092, Zürich, Switzerland
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland
| | - Costanza Giampietro
- Institute for Mechanical Systems, ETH Zurich, CH-8092, Zürich, Switzerland
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland
| | - Edoardo Mazza
- Institute for Mechanical Systems, ETH Zurich, CH-8092, Zürich, Switzerland
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland
| | - Alexander E Ehret
- Institute for Mechanical Systems, ETH Zurich, CH-8092, Zürich, Switzerland.
- Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600, Dübendorf, Switzerland.
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3
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Pensalfini M, Golde T, Trepat X, Arroyo M. Nonaffine Mechanics of Entangled Networks Inspired by Intermediate Filaments. PHYSICAL REVIEW LETTERS 2023; 131:058101. [PMID: 37595243 DOI: 10.1103/physrevlett.131.058101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 05/04/2023] [Accepted: 06/02/2023] [Indexed: 08/20/2023]
Abstract
Inspired by massive intermediate filament (IF) reorganization in superstretched epithelia, we examine computationally the principles controlling the mechanics of a set of entangled filaments whose ends slide on the cell boundary. We identify an entanglement metric and threshold beyond which random loose networks respond nonaffinely and nonlinearly to stretch by self-organizing into structurally optimal star-shaped configurations. A simple model connecting cellular and filament strains links emergent mechanics to cell geometry, network topology, and filament mechanics. We identify a safety net mechanism in IF networks and provide a framework to harness entanglement in soft fibrous materials.
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Affiliation(s)
- Marco Pensalfini
- Laboratori de Càlcul Numeric (LaCàN), Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain
| | - Tom Golde
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
- Departament de Biomedicina, Facultat de Medicina, Universitat de Barcelona, 08036 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010 Barcelona, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), 08028 Barcelona, Spain
| | - Marino Arroyo
- Laboratori de Càlcul Numeric (LaCàN), Universitat Politècnica de Catalunya-BarcelonaTech, 08034 Barcelona, Spain
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
- Centre Internacional de Mètodes Numèrics en Enginyeria (CIMNE), 08034 Barcelona, Spain
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4
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Kraxner J, Köster S. Influence of phosphorylation on intermediate filaments. Biol Chem 2023; 404:821-827. [PMID: 37074314 PMCID: PMC10506380 DOI: 10.1515/hsz-2023-0140] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 03/31/2023] [Indexed: 04/20/2023]
Abstract
The cytoskeleton of eukaryotes consists of actin filaments, microtubules and intermediate filaments (IF). IFs, in particular, are prone to pronounced phosphorylation, leading to additional charges on the affected amino acids. In recent years, a variety of experiments employing either reconstituted protein systems or living cells have revealed that these altered charge patterns form the basis for a number of very diverse cellular functions and processes, including reversible filament assembly, filament softening, network remodeling, cell migration, interactions with other protein structures, and biochemical signaling.
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Affiliation(s)
- Julia Kraxner
- Max Delbrück Center for Molecular Medicine, Robert-Rössle-Straße 10, D-13125 Berlin, Germany
- German Centre for Cardiovascular Research (DZHK), Partner Site Berlin, D-10785 Berlin, Germany
| | - Sarah Köster
- University of Göttingen, Institute for X-Ray Physics, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), Partner Site Göttingen, D-37075 Göttingen, Germany
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5
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Lorenz C, Forsting J, Style RW, Klumpp S, Köster S. Keratin filament mechanics and energy dissipation are determined by metal-like plasticity. MATTER 2023; 6:2019-2033. [PMID: 37332398 PMCID: PMC10273143 DOI: 10.1016/j.matt.2023.04.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 03/22/2023] [Accepted: 04/24/2023] [Indexed: 06/20/2023]
Abstract
Cell mechanics are determined by an intracellular biopolymer network, including intermediate filaments that are expressed in a cell-type-specific manner. A prominent pair of intermediate filaments are keratin and vimentin, as they are expressed by non-motile and motile cells, respectively. Therefore, the differential expression of these proteins coincides with a change in cellular mechanics and dynamic properties of the cells. This observation raises the question of how the mechanical properties already differ on the single filament level. Here, we use optical tweezers and a computational model to compare the stretching and dissipation behavior of the two filament types. We find that keratin and vimentin filaments behave in opposite ways: keratin filaments elongate but retain their stiffness, whereas vimentin filaments soften but retain their length. This finding is explained by fundamentally different ways to dissipate energy: viscous sliding of subunits within keratin filaments and non-equilibrium α helix unfolding in vimentin filaments.
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Affiliation(s)
- Charlotta Lorenz
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Johanna Forsting
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Robert W. Style
- Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 1-5/10, 8093 Zürich, Switzerland
| | - Stefan Klumpp
- Institute for the Dynamics of Complex Systems, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Max Planck School “Matter to Life”, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Max Planck School “Matter to Life”, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
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6
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Rübsam M, Püllen R, Tellkamp F, Bianco A, Peskoller M, Bloch W, Green KJ, Merkel R, Hoffmann B, Wickström SA, Niessen CM. Polarity signaling balances epithelial contractility and mechanical resistance. Sci Rep 2023; 13:7743. [PMID: 37173371 PMCID: PMC10182030 DOI: 10.1038/s41598-023-33485-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Accepted: 04/13/2023] [Indexed: 05/15/2023] Open
Abstract
Epithelia maintain a functional barrier during tissue turnover while facing varying mechanical stress. This maintenance requires both dynamic cell rearrangements driven by actomyosin-linked intercellular adherens junctions and ability to adapt to and resist extrinsic mechanical forces enabled by keratin filament-linked desmosomes. How these two systems crosstalk to coordinate cellular movement and mechanical resilience is not known. Here we show that in stratifying epithelia the polarity protein aPKCλ controls the reorganization from stress fibers to cortical actomyosin during differentiation and upward movement of cells. Without aPKC, stress fibers are retained resulting in increased contractile prestress. This aberrant stress is counterbalanced by reorganization and bundling of keratins, thereby increasing mechanical resilience. Inhibiting contractility in aPKCλ-/- cells restores normal cortical keratin networks but also normalizes resilience. Consistently, increasing contractile stress is sufficient to induce keratin bundling and enhance resilience, mimicking aPKC loss. In conclusion, our data indicate that keratins sense the contractile stress state of stratified epithelia and balance increased contractility by mounting a protective response to maintain tissue integrity.
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Affiliation(s)
- Matthias Rübsam
- Department Cell Biology of the Skin, University Hospital Cologne, University of Cologne, Cologne, Germany.
- Cologne Excellence Cluster for Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University Hospital Cologne, University of Cologne, Cologne, Germany.
- Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany.
| | - Robin Püllen
- Forschungszentrum Jülich, Institute of Biological Information Processing, IBI-2: Mechanobiology, 52428, Jülich, Germany
| | - Frederik Tellkamp
- Department Cell Biology of the Skin, University Hospital Cologne, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster for Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Alessandra Bianco
- Department Cell Biology of the Skin, University Hospital Cologne, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster for Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
| | - Marc Peskoller
- Department Cell Biology of the Skin, University Hospital Cologne, University of Cologne, Cologne, Germany
- Cologne Excellence Cluster for Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Center for Molecular Medicine Cologne (CMMC), University Hospital Cologne, University of Cologne, Cologne, Germany
| | - Wilhelm Bloch
- Department of Molecular and Cellular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University of Cologne, Cologne, Germany
| | - Kathleen J Green
- Departments of Pathology and Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Rudolf Merkel
- Forschungszentrum Jülich, Institute of Biological Information Processing, IBI-2: Mechanobiology, 52428, Jülich, Germany
| | - Bernd Hoffmann
- Forschungszentrum Jülich, Institute of Biological Information Processing, IBI-2: Mechanobiology, 52428, Jülich, Germany
| | - Sara A Wickström
- Cologne Excellence Cluster for Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
- Max Planck Institute for Biology of Ageing, 50931, Cologne, Germany
- Stem Cells and Metabolism Research Program, Faculty of Medicine, University of Helsinki, 00290, Helsinki, Finland
| | - Carien M Niessen
- Department Cell Biology of the Skin, University Hospital Cologne, University of Cologne, Cologne, Germany.
- Cologne Excellence Cluster for Stress Responses in Ageing-Associated Diseases (CECAD), University of Cologne, Cologne, Germany.
- Center for Molecular Medicine Cologne (CMMC), University Hospital Cologne, University of Cologne, Cologne, Germany.
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7
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Liu S, Li Y, Hong Y, Wang M, Zhang H, Ma J, Qu K, Huang G, Lu TJ. Mechanotherapy in oncology: Targeting nuclear mechanics and mechanotransduction. Adv Drug Deliv Rev 2023; 194:114722. [PMID: 36738968 DOI: 10.1016/j.addr.2023.114722] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 12/23/2022] [Accepted: 01/28/2023] [Indexed: 02/05/2023]
Abstract
Mechanotherapy is proposed as a new option for cancer treatment. Increasing evidence suggests that characteristic differences are present in the nuclear mechanics and mechanotransduction of cancer cells compared with those of normal cells. Recent advances in understanding nuclear mechanics and mechanotransduction provide not only further insights into the process of malignant transformation but also useful references for developing new therapeutic approaches. Herein, we present an overview of the alterations of nuclear mechanics and mechanotransduction in cancer cells and highlight their implications in cancer mechanotherapy.
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Affiliation(s)
- Shaobao Liu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China; MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures, Nanjing University of Aeronautics, Nanjing 210016, PR China
| | - Yuan Li
- MOE Key Laboratory of Biomedical Information Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Yuan Hong
- MOE Key Laboratory of Biomedical Information Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China; National Science Foundation Science and Technology Center for Engineering Mechanobiology, Washington University, St. Louis, MO 63130, USA
| | - Ming Wang
- MOE Key Laboratory of Biomedical Information Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Hao Zhang
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China; MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures, Nanjing University of Aeronautics, Nanjing 210016, PR China
| | - Jinlu Ma
- Department of Radiation Oncology, the First Affiliated Hospital, Xian Jiaotong University, Xi'an 710061, PR China
| | - Kai Qu
- Department of Hepatobiliary Surgery, the First Affiliated Hospital, Xian Jiaotong University, Xi'an 710061, PR China
| | - Guoyou Huang
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072, PR China.
| | - Tian Jian Lu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China; MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures, Nanjing University of Aeronautics, Nanjing 210016, PR China.
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8
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Haghizadeh A, Iftikhar M, Dandpat SS, Simpson T. Looking at Biomolecular Interactions through the Lens of Correlated Fluorescence Microscopy and Optical Tweezers. Int J Mol Sci 2023; 24:2668. [PMID: 36768987 PMCID: PMC9916863 DOI: 10.3390/ijms24032668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/19/2022] [Accepted: 01/26/2023] [Indexed: 02/01/2023] Open
Abstract
Understanding complex biological events at the molecular level paves the path to determine mechanistic processes across the timescale necessary for breakthrough discoveries. While various conventional biophysical methods provide some information for understanding biological systems, they often lack a complete picture of the molecular-level details of such dynamic processes. Studies at the single-molecule level have emerged to provide crucial missing links to understanding complex and dynamic pathways in biological systems, which are often superseded by bulk biophysical and biochemical studies. Latest developments in techniques combining single-molecule manipulation tools such as optical tweezers and visualization tools such as fluorescence or label-free microscopy have enabled the investigation of complex and dynamic biomolecular interactions at the single-molecule level. In this review, we present recent advances using correlated single-molecule manipulation and visualization-based approaches to obtain a more advanced understanding of the pathways for fundamental biological processes, and how this combination technique is facilitating research in the dynamic single-molecule (DSM), cell biology, and nanomaterials fields.
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9
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Nunes Vicente F, Lelek M, Tinevez JY, Tran QD, Pehau-Arnaudet G, Zimmer C, Etienne-Manneville S, Giannone G, Leduc C. Molecular organization and mechanics of single vimentin filaments revealed by super-resolution imaging. SCIENCE ADVANCES 2022; 8:eabm2696. [PMID: 35213220 PMCID: PMC8880768 DOI: 10.1126/sciadv.abm2696] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 01/11/2022] [Indexed: 05/30/2023]
Abstract
Intermediate filaments (IFs) are involved in key cellular functions including polarization, migration, and protection against large deformations. These functions are related to their remarkable ability to extend without breaking, a capacity that should be determined by the molecular organization of subunits within filaments. However, this structure-mechanics relationship remains poorly understood at the molecular level. Here, using super-resolution microscopy (SRM), we show that vimentin filaments exhibit a ~49-nanometer axial repeat both in cells and in vitro. As unit-length filaments (ULFs) were measured at ~59 nanometers, this demonstrates a partial overlap of ULFs during filament assembly. Using an SRM-compatible stretching device, we also provide evidence that the extensibility of vimentin is due to the unfolding of its subunits and not to their sliding, thus establishing a direct link between the structural organization and its mechanical properties. Overall, our results pave the way for future studies of IF assembly, mechanical, and structural properties in cells.
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Affiliation(s)
- Filipe Nunes Vicente
- Institut Interdisciplinaire des Neurosciences, CNRS UMR 5297, Université de Bordeaux, Bordeaux F-33000, France
| | - Mickael Lelek
- Imaging and Modeling Unit, Institut Pasteur, CNRS UMR 3691, Paris F-75015, France
| | - Jean-Yves Tinevez
- Image Analysis Hub, 2RT / DTPS, Institut Pasteur, Paris F-75015 , France
| | - Quang D. Tran
- Cell Polarity, Migration and Cancer Unit, Institut Pasteur, CNRS UMR 3691, équipe labellisée Ligue contre le cancer, Paris F-75015, France
- CNRS UMR 7592, Institut Jacques Monod, Université de Paris, Paris F-75013, France
| | - Gerard Pehau-Arnaudet
- CNRS UMR 3528, Institut Pasteur, Paris F-75015, France
- Ultrastructural BioImaging Platform, Institut Pasteur, Paris F-75015, France
| | - Christophe Zimmer
- Imaging and Modeling Unit, Institut Pasteur, CNRS UMR 3691, Paris F-75015, France
| | - Sandrine Etienne-Manneville
- Cell Polarity, Migration and Cancer Unit, Institut Pasteur, CNRS UMR 3691, équipe labellisée Ligue contre le cancer, Paris F-75015, France
| | - Gregory Giannone
- Institut Interdisciplinaire des Neurosciences, CNRS UMR 5297, Université de Bordeaux, Bordeaux F-33000, France
| | - Cécile Leduc
- Cell Polarity, Migration and Cancer Unit, Institut Pasteur, CNRS UMR 3691, équipe labellisée Ligue contre le cancer, Paris F-75015, France
- CNRS UMR 7592, Institut Jacques Monod, Université de Paris, Paris F-75013, France
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10
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Schepers AV, Kraxner J, Lorenz C, Köster S. Mechanics of Single Vimentin Intermediate Filaments Under Load. Methods Mol Biol 2022; 2478:677-700. [PMID: 36063338 DOI: 10.1007/978-1-0716-2229-2_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The eukaryotic cytoskeleton consists of three different types of biopolymers - microtubules, actin filaments, and intermediate filaments - and provides cells with versatile mechanical properties, combining stability and flexibility. The unique molecular structure of intermediate filaments leads to high extensibility and stability under load. With high laser power dual optical tweezers, the mechanical properties of intermediate filaments may be investigated, while monitoring the extension with fluorescence microscopy. Here, we provide detailed protocols for the preparation of single vimentin intermediate filaments and general measurement protocols for (i) stretching experiments, (ii) repeated loading and relaxation cycles, and (iii) force-clamp experiments. We describe methods for the analysis of the experimental data in combination with computational modeling approaches.
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Affiliation(s)
- Anna V Schepers
- University of Göttingen, Institute for X-Ray Physics, Göttingen, Germany
| | - Julia Kraxner
- University of Göttingen, Institute for X-Ray Physics, Göttingen, Germany
| | - Charlotta Lorenz
- University of Göttingen, Institute for X-Ray Physics, Göttingen, Germany
| | - Sarah Köster
- University of Göttingen, Institute for X-Ray Physics, Göttingen, Germany.
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11
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Wiche G. Plectin-Mediated Intermediate Filament Functions: Why Isoforms Matter. Cells 2021; 10:cells10082154. [PMID: 34440923 PMCID: PMC8391331 DOI: 10.3390/cells10082154] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/13/2021] [Accepted: 08/17/2021] [Indexed: 11/26/2022] Open
Abstract
This essay focuses on the role of plectin and its various isoforms in mediating intermediate filament (IF) network functions. It is based on previous studies that provided comprehensive evidence for a concept where plectin acts as an IF recruiter, and plectin-mediated IF networking and anchoring are key elements in IF function execution. Here, plectin’s global role as modulator of IF functionality is viewed from different perspectives, including the mechanical stabilization of IF networks and their docking platforms, contribution to cellular viscoelasticity and mechanotransduction, compartmentalization and control of the actomyosin machinery, connections to the microtubule system, and mechanisms and specificity of isoform targeting. Arguments for IF networks and plectin acting as mutually dependent partners are also given. Lastly, a working model is presented that describes a unifying mechanism underlying how plectin–IF networks mechanically control and propagate actomyosin-generated forces, affect microtubule dynamics, and contribute to mechanotransduction.
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Affiliation(s)
- Gerhard Wiche
- Max Perutz Laboratories, Department of Biochemistry and Cell Biology, University of Vienna, 1030 Vienna, Austria
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12
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Bend, Push, Stretch: Remarkable Structure and Mechanics of Single Intermediate Filaments and Meshworks. Cells 2021; 10:cells10081960. [PMID: 34440729 PMCID: PMC8394331 DOI: 10.3390/cells10081960] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/22/2021] [Accepted: 07/28/2021] [Indexed: 12/11/2022] Open
Abstract
The cytoskeleton of the eukaryotic cell provides a structural and functional scaffold enabling biochemical and cellular functions. While actin and microtubules form the main framework of the cell, intermediate filament networks provide unique mechanical properties that increase the resilience of both the cytoplasm and the nucleus, thereby maintaining cellular function while under mechanical pressure. Intermediate filaments (IFs) are imperative to a plethora of regulatory and signaling functions in mechanotransduction. Mutations in all types of IF proteins are known to affect the architectural integrity and function of cellular processes, leading to debilitating diseases. The basic building block of all IFs are elongated α-helical coiled-coils that assemble hierarchically into complex meshworks. A remarkable mechanical feature of IFs is the capability of coiled-coils to metamorphize into β-sheets under stress, making them one of the strongest and most resilient mechanical entities in nature. Here, we discuss structural and mechanical aspects of IFs with a focus on nuclear lamins and vimentin.
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13
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Intermediate Filaments from Tissue Integrity to Single Molecule Mechanics. Cells 2021; 10:cells10081905. [PMID: 34440673 PMCID: PMC8392029 DOI: 10.3390/cells10081905] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 12/22/2022] Open
Abstract
Cytoplasmic intermediate filaments (IFs), which together with actin and microtubules form the cytoskeleton, are composed of a large and diverse family of proteins. Efforts to elucidate the molecular mechanisms responsible for IF-associated diseases increasingly point towards a major contribution of IFs to the cell’s ability to adapt, resist and respond to mechanical challenges. From these observations, which echo the impressive resilience of IFs in vitro, we here discuss the role of IFs as master integrators of cell and tissue mechanics. In this review, we summarize our current understanding of the contribution of IFs to cell and tissue mechanics and explain these results in light of recent in vitro studies that have investigated physical properties of single IFs and IF networks. Finally, we highlight how changes in IF gene expression, network assembly dynamics, and post-translational modifications can tune IF properties to adapt cell and tissue mechanics to changing environments.
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Multiscale mechanics and temporal evolution of vimentin intermediate filament networks. Proc Natl Acad Sci U S A 2021; 118:2102026118. [PMID: 34187892 DOI: 10.1073/pnas.2102026118] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The cytoskeleton, an intricate network of protein filaments, motor proteins, and cross-linkers, largely determines the mechanical properties of cells. Among the three filamentous components, F-actin, microtubules, and intermediate filaments (IFs), the IF network is by far the most extensible and resilient to stress. We present a multiscale approach to disentangle the three main contributions to vimentin IF network mechanics-single-filament mechanics, filament length, and interactions between filaments-including their temporal evolution. Combining particle tracking, quadruple optical trapping, and computational modeling, we derive quantitative information on the strength and kinetics of filament interactions. Specifically, we find that hydrophobic contributions to network mechanics enter mostly via filament-elongation kinetics, whereas electrostatics have a direct influence on filament-filament interactions.
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15
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Elbalasy I, Mollenkopf P, Tutmarc C, Herrmann H, Schnauß J. Keratins determine network stress responsiveness in reconstituted actin-keratin filament systems. SOFT MATTER 2021; 17:3954-3962. [PMID: 33724291 DOI: 10.1039/d0sm02261f] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The cytoskeleton is a major determinant of cell mechanics, and alterations in the central mechanical aspects of cells are observed during many pathological situations. Therefore, it is essential to investigate the interplay between the main filament systems of the cytoskeleton in the form of composite networks. Here, we investigate the role of keratin intermediate filaments (IFs) in network strength by studying in vitro reconstituted actin and keratin 8/18 composite filament networks via bulk shear rheology. We co-polymerized these structural proteins in varying ratios and recorded how their relative content affects the overall mechanical response of the various composites. For relatively small deformations, we found that all composites exhibited an intermediate linear viscoelastic behaviour compared to that of the pure networks. In stark contrast, when larger deformations were imposed the composites displayed increasing strain stiffening behaviour with increasing keratin content. The extent of strain stiffening is much more pronounced than in corresponding experiments performed with vimentin IF as a composite network partner for actin. Our results provide new insights into the mechanical interplay between actin and keratin filaments in which keratin provides reinforcement to actin. This interplay may contribute to the overall integrity of cells. Hence, the high keratin 8/18 content of mechanically stressed simple epithelial cell layers, as found in the lung and the intestine, provides an explanation for their exceptional stability.
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Affiliation(s)
- Iman Elbalasy
- Peter-Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
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Jabre S, Hleihel W, Coirault C. Nuclear Mechanotransduction in Skeletal Muscle. Cells 2021; 10:cells10020318. [PMID: 33557157 PMCID: PMC7913907 DOI: 10.3390/cells10020318] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 12/11/2022] Open
Abstract
Skeletal muscle is composed of multinucleated, mature muscle cells (myofibers) responsible for contraction, and a resident pool of mononucleated muscle cell precursors (MCPs), that are maintained in a quiescent state in homeostatic conditions. Skeletal muscle is remarkable in its ability to adapt to mechanical constraints, a property referred as muscle plasticity and mediated by both MCPs and myofibers. An emerging body of literature supports the notion that muscle plasticity is critically dependent upon nuclear mechanotransduction, which is transduction of exterior physical forces into the nucleus to generate a biological response. Mechanical loading induces nuclear deformation, changes in the nuclear lamina organization, chromatin condensation state, and cell signaling, which ultimately impacts myogenic cell fate decisions. This review summarizes contemporary insights into the mechanisms underlying nuclear force transmission in MCPs and myofibers. We discuss how the cytoskeleton and nuclear reorganizations during myogenic differentiation may affect force transmission and nuclear mechanotransduction. We also discuss how to apply these findings in the context of muscular disorders. Finally, we highlight current gaps in knowledge and opportunities for further research in the field.
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Affiliation(s)
- Saline Jabre
- Sorbonne Université, INSERM UMRS-974 and Institut de Myologie, 75013 Paris, France;
- Department of Biology, Faculty of Arts and Sciences, Holy Spirit University of Kasik (USEK), Jounieh 446, Lebanon;
| | - Walid Hleihel
- Department of Biology, Faculty of Arts and Sciences, Holy Spirit University of Kasik (USEK), Jounieh 446, Lebanon;
- Department of Basic Health Sciences, Faculty of Medicine, Holy Spirit University of Kaslik (USEK), Jounieh 446, Lebanon
| | - Catherine Coirault
- Sorbonne Université, INSERM UMRS-974 and Institut de Myologie, 75013 Paris, France;
- Correspondence:
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Kraxner J, Lorenz C, Menzel J, Parfentev I, Silbern I, Denz M, Urlaub H, Schwappach B, Köster S. Post-translational modifications soften vimentin intermediate filaments. NANOSCALE 2021; 13:380-387. [PMID: 33351020 DOI: 10.1039/d0nr07322a] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The mechanical properties of biological cells are determined by the cytoskeleton, a composite biopolymer network consisting of microtubules, actin filaments and intermediate filaments (IFs). By differential expression of cytoskeletal proteins, modulation of the network architecture and interactions between the filaments, cell mechanics may be adapted to varying requirements on the cell. Here, we focus on the intermediate filament protein vimentin and introduce post-translational modifications as an additional, much faster mechanism for mechanical modulation. We study the impact of phosphorylation on filament mechanics by recording force-strain curves using optical traps. Partial phosphorylation softens the filaments. We show that binding of the protein 14-3-3 to phosphorylated vimentin IFs further enhances this effect and speculate that in the cell 14-3-3 may serve to preserve the softening and thereby the altered cell mechanics. We explain our observation by the additional charges introduced during phosphorylation.
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Affiliation(s)
- Julia Kraxner
- Institute for X-Ray Physics, University of Göttingen, 37077 Göttingen, Germany.
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Schepers AV, Lorenz C, Köster S. Tuning intermediate filament mechanics by variation of pH and ion charges. NANOSCALE 2020; 12:15236-15245. [PMID: 32642745 DOI: 10.1039/d0nr02778b] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The cytoskeleton is formed by three types of filamentous proteins - microtubules, actin filaments, and intermediate filaments (IFs) - and enables cells to withstand external and internal forces. Vimentin is the most abundant IF protein in humans and assembles into 10 nm diameter filaments with remarkable mechanical properties, such as high extensibility and stability. It is, however, unclear to which extent these properties are influenced by the electrostatic environment. Here, we study the mechanical properties of single vimentin filaments by employing optical trapping combined with microfluidics. Force-strain curves, recorded at varying ion concentrations and pH values, reveal that the mechanical properties of single vimentin IFs are influenced by pH and ion concentration. By combination with Monte Carlo simulations, we relate these altered mechanics to electrostatic interactions of subunits within the filaments. We thus suggest possible mechanisms that allow cells to locally tune their stiffness without remodeling the entire cytoskeleton.
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Affiliation(s)
- Anna V Schepers
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
| | - Charlotta Lorenz
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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van Bodegraven EJ, Etienne-Manneville S. Intermediate filaments against actomyosin: the david and goliath of cell migration. Curr Opin Cell Biol 2020; 66:79-88. [PMID: 32623234 DOI: 10.1016/j.ceb.2020.05.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 03/29/2020] [Accepted: 05/05/2020] [Indexed: 01/09/2023]
Abstract
Intermediate filaments (IFs), together with actin and microtubules, constitute the cytoskeleton and regulate essential biological processes including cell migration. Despite the well-described changes in the composition of IFs in migrating cells, the mechanism by which these changes may contribute to cell migration remains elusive. Recent studies show that IFs control cell migration by impacting the actomyosin machinery. This review discusses how the unique physical properties of IFs, the interplay between IFs and the actomyosin network, and the connection of IFs with cell adhesive structures participate in cell migration. We highlight the biochemical and mechanical mechanisms by which IFs control actomyosin-generated forces to influence migration speed and contribute to nuclear integrity and cell resilience to compressive forces in 2D, as well as in confined 3D migration.
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Affiliation(s)
- Emma J van Bodegraven
- Cell Polarity, Migration and Cancer Unit, Institut Pasteur, UMR3691 CNRS, Equipe Labellisée Ligue Contre le Cancer, F-75015, Paris, France
| | - Sandrine Etienne-Manneville
- Cell Polarity, Migration and Cancer Unit, Institut Pasteur, UMR3691 CNRS, Equipe Labellisée Ligue Contre le Cancer, F-75015, Paris, France.
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