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Shoyer TC, Collins KL, Ham TR, Blanchard AT, Malavade JN, Johns BA, West JL, Hoffman BD. Detection of fluorescent protein mechanical switching in cellulo. CELL REPORTS METHODS 2024:100815. [PMID: 38986612 DOI: 10.1016/j.crmeth.2024.100815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 05/03/2024] [Accepted: 06/17/2024] [Indexed: 07/12/2024]
Abstract
The ability of cells to sense and respond to mechanical forces is critical in many physiological and pathological processes. However, determining the mechanisms by which forces affect protein function inside cells remains challenging. Motivated by in vitro demonstrations of fluorescent proteins (FPs) undergoing reversible mechanical switching of fluorescence, we investigated whether force-sensitive changes in FP function could be visualized in cells. Guided by a computational model of FP mechanical switching, we develop a formalism for its detection in Förster resonance energy transfer (FRET)-based biosensors and demonstrate its occurrence in cellulo within a synthetic actin crosslinker and the mechanical linker protein vinculin. We find that in cellulo mechanical switching is reversible and altered by manipulation of cell force generation, external stiffness, and force-sensitive bond dynamics of the biosensor. This work describes a framework for assessing FP mechanical stability and provides a means of probing force-sensitive protein function inside cells.
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Affiliation(s)
- T Curtis Shoyer
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA
| | - Kasie L Collins
- Department of Chemistry, Duke University, Durham NC 27708, USA
| | - Trevor R Ham
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA
| | - Aaron T Blanchard
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA
| | - Juilee N Malavade
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA
| | - Benjamin A Johns
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA
| | - Jennifer L West
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA; Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham NC 27708, USA.
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2
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Shoyer TC, Collins KL, Ham TR, Blanchard AT, Malavade JN, West JL, Hoffman BD. Detection of Fluorescent Protein Mechanical Switching in Cellulo. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.10.575065. [PMID: 38260589 PMCID: PMC10802509 DOI: 10.1101/2024.01.10.575065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
The ability of cells to sense and respond to mechanical forces is critical in many physiological and pathological processes. However, the mechanisms by which forces affect protein function inside cells remain unclear. Motivated by in vitro demonstrations of fluorescent proteins (FPs) undergoing reversible mechanical switching of fluorescence, we investigated if force-sensitive changes in FP function could be visualized in cells. Guided by a computational model of FP mechanical switching, we develop a formalism for its detection in Förster resonance energy transfer (FRET)-based biosensors and demonstrate its occurrence in cellulo in a synthetic actin-crosslinker and the mechanical linker protein vinculin. We find that in cellulo mechanical switching is reversible and altered by manipulation of cellular force generation as well as force-sensitive bond dynamics of the biosensor. Together, this work describes a new framework for assessing FP mechanical stability and provides a means of probing force-sensitive protein function inside cells. MOTIVATION The ability of cells to sense mechanical forces is critical in developmental, physiological, and pathological processes. Cells sense mechanical cues via force-induced alterations in protein structure and function, but elucidation of the molecular mechanisms is hindered by the lack of approaches to directly probe the effect of forces on protein structure and function inside cells. Motivated by in vitro observations of reversible fluorescent protein mechanical switching, we developed an approach for detecting fluorescent protein mechanical switching in cellulo . This enables the visualization of force-sensitive protein function inside living cells.
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3
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Chirasani VR, Khan MAI, Malavade JN, Dokholyan NV, Hoffman BD, Campbell SL. Molecular basis and cellular functions of vinculin-actin directional catch bonding. Nat Commun 2023; 14:8300. [PMID: 38097542 PMCID: PMC10721916 DOI: 10.1038/s41467-023-43779-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 11/20/2023] [Indexed: 12/17/2023] Open
Abstract
The ability of cells and tissues to respond differentially to mechanical forces applied in distinct directions is mediated by the ability of load-bearing proteins to preferentially maintain physical linkages in certain directions. However, the molecular basis and biological consequences of directional force-sensitive binding remain unclear. Vinculin (Vcn) is a load-bearing linker protein that exhibits directional catch bonding due to interactions between the Vcn tail domain (Vt) and filamentous (F)-actin. We developed a computational approach to predict Vcn residues involved in directional catch bonding and produced a set of associated Vcn variants with unaltered Vt structure, actin binding, or phospholipid interactions. Incorporation of the variants did not affect Vcn activation but reduced Vcn loading and altered exchange dynamics, consistent with the loss of directional catch bonding. Expression of Vcn variants perturbed the coordination of subcellular structures and cell migration, establishing key cellular functions for Vcn directional catch bonding.
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Affiliation(s)
- Venkat R Chirasani
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mohammad Ashhar I Khan
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Juilee N Malavade
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
| | - Nikolay V Dokholyan
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, USA.
- Department of Biochemistry & Molecular Biology, Penn State College of Medicine, Hershey, PA, USA.
- Department of Chemistry, Penn State College of Medicine, Hershey, PA, USA.
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC, USA.
- Department of Cell Biology, Duke University, Durham, NC, USA.
| | - Sharon L Campbell
- Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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4
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Amiri S, Muresan C, Shang X, Huet-Calderwood C, Schwartz MA, Calderwood DA, Murrell M. Intracellular tension sensor reveals mechanical anisotropy of the actin cytoskeleton. Nat Commun 2023; 14:8011. [PMID: 38049429 PMCID: PMC10695988 DOI: 10.1038/s41467-023-43612-5] [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: 01/12/2023] [Accepted: 11/15/2023] [Indexed: 12/06/2023] Open
Abstract
The filamentous actin (F-actin) cytoskeleton is a composite material consisting of cortical actin and bundled F-actin stress fibers, which together mediate the mechanical behaviors of the cell, from cell division to cell migration. However, as mechanical forces are typically measured upon transmission to the extracellular matrix, the internal distribution of forces within the cytoskeleton is unknown. Likewise, how distinct F-actin architectures contribute to the generation and transmission of mechanical forces is unclear. Therefore, we have developed a molecular tension sensor that embeds into the F-actin cytoskeleton. Using this sensor, we measure tension within stress fibers and cortical actin, as the cell is subject to uniaxial stretch. We find that the mechanical response, as measured by FRET, depends on the direction of applied stretch relative to the cell's axis of alignment. When the cell is aligned parallel to the direction of the stretch, stress fibers and cortical actin both accumulate tension. By contrast, when aligned perpendicular to the direction of stretch, stress fibers relax tension while the cortex accumulates tension, indicating mechanical anisotropy within the cytoskeleton. We further show that myosin inhibition regulates this anisotropy. Thus, the mechanical anisotropy of the cell and the coordination between distinct F-actin architectures vary and depend upon applied load.
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Affiliation(s)
- Sorosh Amiri
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA
- Department of Mechanical Engineering and Material Science, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
| | - Camelia Muresan
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
| | - Xingbo Shang
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
| | | | - Martin A Schwartz
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
- Department of Cell Biology, 333 Cedar St, Yale University, New Haven, CT, 06510, USA
- Yale Cardiovascular Research Center, 300 George St, New Haven, CT, 06511, USA
| | - David A Calderwood
- Department of Pharmacology, 333 Cedar St, Yale University, New Haven, CT, 06510, USA
- Department of Cell Biology, 333 Cedar St, Yale University, New Haven, CT, 06510, USA
| | - Michael Murrell
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA.
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA.
- Department of Physics, 217 Prospect Street, Yale University, New Haven, CT, 06511, USA.
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Liu K, He X, Zhang Z, Sun T, Chen J, Chen C, Wen W, Ding S, Liu M, Zhou C, Luo B. Highly anisotropic and elastic cellulosic scaffold guiding cell orientation and osteogenic differentiation via topological and mechanical cues. Carbohydr Polym 2023; 321:121292. [PMID: 37739527 DOI: 10.1016/j.carbpol.2023.121292] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 08/01/2023] [Accepted: 08/10/2023] [Indexed: 09/24/2023]
Abstract
Inspired by the similarity of anisotropic channels in wood to the canals of bone, the elastic wood-derived (EW) scaffolds with anisotropic channels were prepared via simple delignification treatment of natural wood (NW). We hypothesize that the degree of delignification will lead to differences in mechanical properties of scaffolds, which in turn directly affect the behaviors and fate of stem cells. The delignification process did not destroy the anisotropic channel structure of the scaffolds, but endowed the scaffolds with good elasticity and rapid stress relaxation. Interestingly, the micron-scale anisotropic channels of the scaffolds can highly promote the polarization of cells along the direction of channels. We also found that the alkaline phosphatase of EW scaffold can reach to about 13.1 U/gprot, which was about double that of NW scaffold. Moreover, the longer the delignification time, the better the osteogenic activity of the EW scaffolds. We further hypothesize that the osteogenic activity of scaffolds is related to the stress relaxation properties. The immunofluorescence staining showed that when the stress relaxation time of scaffold was shortened to about 10 s, the nuclear ratio of YAP of scaffold increased to 0.22, which well supports our hypothesis.
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Affiliation(s)
- Kun Liu
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China
| | - Xiangheng He
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China
| | - Zhaoyu Zhang
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China
| | - Tianyi Sun
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China
| | - Jiaqing Chen
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China
| | - Chunhua Chen
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China
| | - Wei Wen
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China; Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632, PR China
| | - Shan Ding
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China; Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632, PR China
| | - Mingxian Liu
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China; Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632, PR China
| | - Changren Zhou
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China; Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632, PR China
| | - Binghong Luo
- Biomaterial Research Laboratory, Department of Material Science and Engineering, College of Chemistry and Materials, Jinan University, Guangzhou 510632, PR China; Engineering Research Center of Artificial Organs and Materials, Ministry of Education, Guangzhou 510632, PR China.
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Dubois C, Houel-Renault L, Erard M, Boustany NN, Westbrook N. Förster resonance energy transfer efficiency measurements on vinculin tension sensors at focal adhesions using a simple and cost-effective setup. JOURNAL OF BIOMEDICAL OPTICS 2023; 28:082808. [PMID: 37441563 PMCID: PMC10335361 DOI: 10.1117/1.jbo.28.8.082808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 05/20/2023] [Accepted: 05/23/2023] [Indexed: 07/15/2023]
Abstract
Significance Forces inside cells play a fundamental role in tissue growth, affecting important processes such as cancer cell migration or tissue repair after injury. Förster resonance energy transfer (FRET)-based tension sensors are a remarkable tool for studying these forces and should be made easier to use. Aim We prove that absolute FRET efficiency can be measured on a simple setup, an order of magnitude more cost-effective than a standard FRET microscopy setup, by applying it to vinculin tension sensors (VinTS) at the focal adhesions of live CHO-K1 cells. Approach Our setup located at Université Paris-Saclay acquires donor and acceptor fluorescence in parallel on two low-cost CMOS cameras and uses two LEDs for rapid switching of the excitation wavelength at a reduced cost. The calibration required to extract FRET efficiency was achieved using a single construct (TSMod). FRET efficiencies were measured for VinTS and the tail-less control VinTL, lacking the actin-binding domain of vinculin. Measurements were confirmed on the same cell type using a more standard intensity-based setup located at Rutgers University. Results The average FRET efficiency of VinTS (22.0 % ± 4 % ) over more than 10,000 focal adhesions is significantly lower (p < 10 - 6 ) than that of VinTL (30.4 % ± 5 % ), our control that is insensitive to force, in agreement with the force exerted on vinculin at focal adhesions. Attachment of the CHO-K1 cells on fibronectin decreases FRET efficiency, thus increasing the force, compared with poly-lysine. FRET efficiency for the VinTL control is consistent with all measurements currently available in the literature, confirming the validity of our measurements and hence of our simpler setup. Conclusions Force measurements, resolved spatially inside a cell, can be achieved using FRET-based tension sensors with a cost effective intensity-based setup. This will facilitate combining FRET with techniques for applying controlled forces such as optical tweezers.
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Affiliation(s)
- Camille Dubois
- Université Paris-Saclay, Institut d’Optique Graduate School, CNRS, Laboratoire Charles Fabry, Palaiseau, France
| | - Ludivine Houel-Renault
- Université Paris-Saclay, Institut des Sciences Moléculaires d’Orsay, CNRS, Centre de Photonique pour la Biologie et les Matériaux, Orsay, France
| | - Marie Erard
- Université Paris-Saclay, Institut de Chimie Physique, CNRS, Orsay, France
| | - Nada N. Boustany
- Rutgers University, Department of Biomedical Engineering, Piscataway, New Jersey, United States
| | - Nathalie Westbrook
- Université Paris-Saclay, Institut d’Optique Graduate School, CNRS, Laboratoire Charles Fabry, Palaiseau, France
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7
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Tao A, LaCroix AS, Shoyer TC, Venkatraman V, Xu KL, Feiger B, Hoffman BD. Identifying constitutive and context-specific molecular-tension-sensitive protein recruitment within focal adhesions. Dev Cell 2023; 58:522-534.e7. [PMID: 36924770 PMCID: PMC10080727 DOI: 10.1016/j.devcel.2023.02.015] [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: 05/06/2022] [Revised: 09/28/2022] [Accepted: 02/20/2023] [Indexed: 03/17/2023]
Abstract
Mechanosensitive processes often rely on adhesion structures to strengthen, or mature, in response to applied loads. However, a limited understanding of how the molecular tensions that are experienced by a particular protein affect the recruitment of other proteins represents a major obstacle in the way of deciphering molecular mechanisms that underlie mechanosensitive processes. Here, we describe an imaging-based technique, termed fluorescence-tension co-localization (FTC), for studying molecular-tension-sensitive protein recruitment inside cells. Guided by discrete time Markov chain simulations of protein recruitment, we integrate immunofluorescence labeling, molecular tension sensors, and machine learning to determine the sensitivity, specificity, and context dependence of molecular-tension-sensitive protein recruitment. The application of FTC to the mechanical linker protein vinculin in mouse embryonic fibroblasts reveals constitutive and context-specific molecular-tension-sensitive protein recruitment that varies with adhesion maturation. FTC overcomes limitations associated with the alteration of numerous proteins during the manipulation of cell contractility, providing molecularly specific insights into tension-sensitive protein recruitment.
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Affiliation(s)
- Arnold Tao
- Biomedical Engineering, Duke University, Durham, NC, USA
| | | | | | | | - Karen L Xu
- Biomedical Engineering, Duke University, Durham, NC, USA
| | - Bradley Feiger
- Biomedical Engineering, Duke University, Durham, NC, USA
| | - Brenton D Hoffman
- Biomedical Engineering, Duke University, Durham, NC, USA; Cell Biology, Duke University, Durham, NC, USA.
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8
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Shoyer TC, Gates EM, Cabe JI, Conway DE, Hoffman BD. Coupling During Collective Cell Migration is Controlled by a Vinculin Mechanochemical Switch. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.13.523997. [PMID: 36711698 PMCID: PMC9882183 DOI: 10.1101/2023.01.13.523997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Collective cell migration (CCM) plays important roles in development, physiological, and pathological processes. A key feature of CCM is the dynamic mechanical coupling between cells, which enables both long-range coordination and local rearrangements. This coupling requires the ability of cell adhesions to adapt to forces. Recent efforts have identified key proteins and implicated cellular-scale mechanical properties, but how key proteins give rise to these larger-scale mechanical processes is unclear. Using force-sensitive biosensors, cell migration assays, and molecular clutch models, we sought a molecular understanding of adhesion strengthening that could bridge this gap. We found that the mechanical linker protein vinculin bears substantial loads at AJs, FAs, and in the cytoplasm during epithelial sheet migration, and we identified a switch-like residue on vinculin that regulates its conformation and loading at the AJs during CCM. In vinculin KO-rescue, this switch jointly controlled the speed and coupling length-scale of CCM, which suggested changes in adhesion-based friction. To test this, we developed molecularly detailed friction clutch models of the FA and AJ. They show that open, loaded vinculin increases friction in adhesive structures, with larger affects observed in AJs. Thus, this work elucidates how load-bearing linker proteins can be regulated to alter mechanical properties of cells and enable rapid tuning of mechanical coupling in CCM.
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9
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Mierke CT. Viscoelasticity, Like Forces, Plays a Role in Mechanotransduction. Front Cell Dev Biol 2022; 10:789841. [PMID: 35223831 PMCID: PMC8864183 DOI: 10.3389/fcell.2022.789841] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/11/2022] [Indexed: 12/13/2022] Open
Abstract
Viscoelasticity and its alteration in time and space has turned out to act as a key element in fundamental biological processes in living systems, such as morphogenesis and motility. Based on experimental and theoretical findings it can be proposed that viscoelasticity of cells, spheroids and tissues seems to be a collective characteristic that demands macromolecular, intracellular component and intercellular interactions. A major challenge is to couple the alterations in the macroscopic structural or material characteristics of cells, spheroids and tissues, such as cell and tissue phase transitions, to the microscopic interferences of their elements. Therefore, the biophysical technologies need to be improved, advanced and connected to classical biological assays. In this review, the viscoelastic nature of cytoskeletal, extracellular and cellular networks is presented and discussed. Viscoelasticity is conceptualized as a major contributor to cell migration and invasion and it is discussed whether it can serve as a biomarker for the cells’ migratory capacity in several biological contexts. It can be hypothesized that the statistical mechanics of intra- and extracellular networks may be applied in the future as a powerful tool to explore quantitatively the biomechanical foundation of viscoelasticity over a broad range of time and length scales. Finally, the importance of the cellular viscoelasticity is illustrated in identifying and characterizing multiple disorders, such as cancer, tissue injuries, acute or chronic inflammations or fibrotic diseases.
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10
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Lavrenyuk K, Conway D, Dahl KN. Imaging methods in mechanosensing: a historical perspective and visions for the future. Mol Biol Cell 2021; 32:842-854. [PMID: 33788578 PMCID: PMC8108522 DOI: 10.1091/mbc.e20-10-0671] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Over the past three decades, as mechanobiology has become a distinct area of study, researchers have developed novel imaging tools to discover the pathways of biomechanical signaling. Early work with substrate engineering and particle tracking demonstrated the importance of cell–extracellular matrix interactions on the cell cycle as well as the mechanical flux of the intracellular environment. Most recently, tension sensor approaches allowed directly measuring tension in cell–cell and cell–substrate interactions. We retrospectively analyze how these various optical techniques progressed the field and suggest our vision forward for a unified theory of cell mechanics, mapping cellular mechanosensing, and novel biomedical applications for mechanobiology.
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Affiliation(s)
- Kirill Lavrenyuk
- Carnegie Mellon University, College of Engineering, Pittsburgh, PA 15213
| | - Daniel Conway
- Virginia Commonwealth University, College of Engineering, Richmond, VA 23284
| | - Kris Noel Dahl
- Carnegie Mellon University, College of Engineering, Pittsburgh, PA 15213
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11
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Déjardin T, Carollo PS, Sipieter F, Davidson PM, Seiler C, Cuvelier D, Cadot B, Sykes C, Gomes ER, Borghi N. Nesprins are mechanotransducers that discriminate epithelial-mesenchymal transition programs. J Cell Biol 2021; 219:152020. [PMID: 32790861 PMCID: PMC7659719 DOI: 10.1083/jcb.201908036] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Revised: 04/23/2020] [Accepted: 07/21/2020] [Indexed: 01/15/2023] Open
Abstract
LINC complexes are transmembrane protein assemblies that physically connect the nucleoskeleton and cytoskeleton through the nuclear envelope. Dysfunctions of LINC complexes are associated with pathologies such as cancer and muscular disorders. The mechanical roles of LINC complexes are poorly understood. To address this, we used genetically encoded FRET biosensors of molecular tension in a nesprin protein of the LINC complex of fibroblastic and epithelial cells in culture. We exposed cells to mechanical, genetic, and pharmacological perturbations, mimicking a range of physiological and pathological situations. We show that nesprin experiences tension generated by the cytoskeleton and acts as a mechanical sensor of cell packing. Moreover, nesprin discriminates between inductions of partial and complete epithelial–mesenchymal transitions. We identify the implicated mechanisms, which involve α-catenin capture at the nuclear envelope by nesprin upon its relaxation, thereby regulating β-catenin transcription. Our data thus implicate LINC complex proteins as mechanotransducers that fine-tune β-catenin signaling in a manner dependent on the epithelial–mesenchymal transition program.
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Affiliation(s)
- Théophile Déjardin
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Pietro Salvatore Carollo
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - François Sipieter
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Patricia M Davidson
- Laboratoire Physico-Chimie Curie, Institut Curie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 168, Sorbonne Universités, Université Paris Sciences et Lettres, Paris, France
| | - Cynthia Seiler
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
| | - Damien Cuvelier
- Institut Curie and Institut Pierre Gilles de Gennes, Université Paris Sciences et Lettres, Centre National de la Recherche Scientifique Unité Mixte de Rercherche 144, Paris, France
| | - Bruno Cadot
- Center for Research in Myology, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 974, Sorbonne Universités, Paris, France
| | - Cecile Sykes
- Laboratoire Physico-Chimie Curie, Institut Curie, Centre National de la Recherche Scientifique Unité Mixte de Recherche 168, Sorbonne Universités, Université Paris Sciences et Lettres, Paris, France
| | - Edgar R Gomes
- Center for Research in Myology, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche 974, Sorbonne Universités, Paris, France.,Instituto de Medecina Molecular, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal.,Instituto de Histologia e Biologia do Desenvolvimento, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Nicolas Borghi
- Université de Paris, Centre National de la Recherche Scientifique, Institut Jacques Monod, Paris, France
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12
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Allahyari Z, Gholizadeh S, Chung HH, Delgadillo LF, Gaborski TR. Micropatterned Poly(ethylene glycol) Islands Disrupt Endothelial Cell-Substrate Interactions Differently from Microporous Membranes. ACS Biomater Sci Eng 2019; 6:959-968. [PMID: 32582838 DOI: 10.1021/acsbiomaterials.9b01584] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Porous membranes are ubiquitous in cell co-culture and tissue-on-a-chip studies. These materials are predominantly chosen for their semi-permeable and size exclusion properties to restrict or permit transmigration and cell-cell communication. However, previous studies have shown pore size, spacing and orientation affect cell behavior including extracellular matrix production and migration. The mechanism behind this behavior is not fully understood. In this study, we fabricated micropatterned non-fouling polyethylene glycol (PEG) islands to mimic pore openings in order to decouple the effect of surface discontinuity from potential grip on the vertical contact area provided by pore wall edges. Similar to previous findings on porous membranes, we found that the PEG islands hindered fibronectin fibrillogenesis with cells on patterned substrates producing shorter fibrils. Additionally, cell migration speed over micropatterned PEG islands was greater than unpatterned controls, suggesting that disruption of cell-substrate interactions by PEG islands promoted a more dynamic and migratory behavior, similarly to enhanced cell migration on microporous membranes. Preferred cellular directionality during migration was nearly indistinguishable between substrates with identically patterned PEG islands and previously reported behavior over micropores of the same geometry, further confirming disruption of cell-substrate interactions as a common mechanism behind the cellular responses on these substrates. Interestingly, compared to respective controls, there were differences in cell spreading and a lower increase in migration speed over PEG islands compared prior results on micropores with identical feature size and spacing. This suggests that membrane pores not only disrupt cell-substrate interactions, but also provide additional physical factors that affect cellular response.
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Affiliation(s)
- Zahra Allahyari
- Department of Microsystems Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA.,Department of Biomedical Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA
| | - Shayan Gholizadeh
- Department of Microsystems Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA.,Department of Biomedical Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA
| | - Henry H Chung
- Department of Biomedical Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA
| | - Luis F Delgadillo
- Department of Biomedical Engineering, University of Rochester, 201 Robert B. Goergen Hall, Rochester, NY 14627, USA
| | - Thomas R Gaborski
- Department of Microsystems Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA.,Department of Biomedical Engineering, Rochester Institute of Technology, 160 Lomb Memorial Drive, Rochester, NY 14623, USA.,Department of Biomedical Engineering, University of Rochester, 201 Robert B. Goergen Hall, Rochester, NY 14627, USA
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13
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Ham TR, Collins KL, Hoffman BD. Molecular Tension Sensors: Moving Beyond Force. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2019; 12:83-94. [PMID: 32864525 DOI: 10.1016/j.cobme.2019.10.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Nearly all cellular processes are sensitive to mechanical inputs, and this plays a major role in diverse physiological processes. Mechanical stimuli are thought to be primarily detected through force-induced changes in protein structure. Approximately a decade ago, molecular tension sensors were created to measure forces across proteins within cells. Since then, an impressive assortment of sensors has been created and provided key insights into mechanotransduction, but comparisons of measurements between various sensors are challenging. In this review, we discuss the different types of molecular tension sensors, provide a system of classification based on their molecular-scale mechanical properties, and highlight how new applications of these sensors are enabling measurements beyond the magnitude of tensile load. We suggest that an expanded understanding of the functionality of these sensors, as well as integration with other techniques, will lead to consensus amongst measurements as well as critical insights into the underlying mechanisms of mechanotransduction.
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Affiliation(s)
- Trevor R Ham
- Duke University, Room 1379 CIEMAS, 101 Science Drive, 27710, United States
| | - Kasie L Collins
- Duke University, Room 1379 CIEMAS, 101 Science Drive, 27710, United States
| | - Brenton D Hoffman
- Duke University, Room 1379 CIEMAS, 101 Science Drive, 27710, United States
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14
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Sengupta S, Rothenberg KE, Li H, Hoffman BD, Bursac N. Altering integrin engagement regulates membrane localization of K ir2.1 channels. J Cell Sci 2019; 132:jcs.225383. [PMID: 31391240 DOI: 10.1242/jcs.225383] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 07/31/2019] [Indexed: 12/26/2022] Open
Abstract
How ion channels localize and distribute on the cell membrane remains incompletely understood. We show that interventions that vary cell adhesion proteins and cell size also affect the membrane current density of inward-rectifier K+ channels (Kir2.1; encoded by KCNJ2) and profoundly alter the action potential shape of excitable cells. By using micropatterning to manipulate the localization and size of focal adhesions (FAs) in single HEK293 cells engineered to stably express Kir2.1 channels or in neonatal rat cardiomyocytes, we establish a robust linear correlation between FA coverage and the amplitude of Kir2.1 current at both the local and whole-cell levels. Confocal microscopy showed that Kir2.1 channels accumulate in membrane proximal to FAs. Selective pharmacological inhibition of key mediators of protein trafficking and the spatially dependent alterations in the dynamics of Kir2.1 fluorescent recovery after photobleaching revealed that the Kir2.1 channels are transported to the cell membrane uniformly, but are preferentially internalized by endocytosis at sites that are distal from FAs. Based on these results, we propose adhesion-regulated membrane localization of ion channels as a fundamental mechanism of controlling cellular electrophysiology via mechanochemical signals, independent of the direct ion channel mechanogating.
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Affiliation(s)
- Swarnali Sengupta
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | | | - Hanjun Li
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Nenad Bursac
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
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15
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Shams H, Hoffman BD, Mofrad MRK. The "Stressful" Life of Cell Adhesion Molecules: On the Mechanosensitivity of Integrin Adhesome. J Biomech Eng 2019; 140:2667887. [PMID: 29272321 DOI: 10.1115/1.4038812] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Indexed: 02/06/2023]
Abstract
Cells have evolved into complex sensory machines that communicate with their microenvironment via mechanochemical signaling. Extracellular mechanical cues trigger complex biochemical pathways in the cell, which regulate various cellular processes. Integrin-mediated focal adhesions (FAs) are large multiprotein complexes, also known as the integrin adhesome, that link the extracellular matrix (ECM) to the actin cytoskeleton, and are part of powerful intracellular machinery orchestrating mechanotransduction pathways. As forces are transmitted across FAs, individual proteins undergo structural and functional changes that involve a conversion of chemical to mechanical energy. The local composition of early adhesions likely defines the regional stress levels and determines the type of newly recruited proteins, which in turn modify the local stress distribution. Various approaches have been used for detecting and exploring molecular mechanisms through which FAs are spatiotemporally regulated, however, many aspects are yet to be understood. Current knowledge on the molecular mechanisms of mechanosensitivity in adhesion proteins is discussed herein along with important questions yet to be addressed, are discussed.
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Affiliation(s)
- Hengameh Shams
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, Berkeley, CA 94720-1762
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, NC 27708
| | - Mohammad R K Mofrad
- Molecular Cell Biomechanics Laboratory, Departments of Bioengineering and Mechanical Engineering, University of California, 208A Stanley Hall #1762, Berkeley, CA 94720-1762.,Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Lab, Berkeley, CA 94720 e-mail:
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16
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Banda OA, Sabanayagam CR, Slater JH. Reference-Free Traction Force Microscopy Platform Fabricated via Two-Photon Laser Scanning Lithography Enables Facile Measurement of Cell-Generated Forces. ACS APPLIED MATERIALS & INTERFACES 2019; 11:18233-18241. [PMID: 31045355 PMCID: PMC8725169 DOI: 10.1021/acsami.9b04362] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Cells sense and respond to the physical nature of their microenvironment by mechanically probing their surroundings via cytoskeletal contractions. The material response to these stresses can be measured via traction force microscopy (TFM). Traditional TFM platforms present several limitations including variable spatial resolution, difficulty in attaining the full three-dimensional (3D) deformation/stress profile, and the requirement to remove or relax the cells being measured to determine the zero-stress state. To overcome these limitations, we developed a two-photon, photochemical coupling approach to fabricate a new TFM platform that provides high-resolution control over the 3D placement of fluorescent fiducial markers for facile measurement of cell-generated shear and normal components of traction forces. The highly controlled placement of the 3D marker array provides a built-in, zero stress state eliminating the need to perturb the cells being measured while also providing increased throughput. Using this platform, we discovered that the magnitude of cell-generated shear and normal force components are linked both spatially and temporally. The facile nature and increased throughput of measuring cell-generated forces afforded by this new platform will be useful to the mechanotransduction community and others.
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Affiliation(s)
- Omar A Banda
- Department of Biomedical Engineering , University of Delaware , 5 Innovation Way , Newark , Delaware 19711 , United States
| | - Chandran R Sabanayagam
- Delaware Biotechnology Institute , University of Delaware , 15 Innovation Way , Newark , Delaware 19711 , United States
| | - John H Slater
- Department of Biomedical Engineering , University of Delaware , 5 Innovation Way , Newark , Delaware 19711 , United States
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17
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Rothenberg KE, Scott DW, Christoforou N, Hoffman BD. Vinculin Force-Sensitive Dynamics at Focal Adhesions Enable Effective Directed Cell Migration. Biophys J 2019; 114:1680-1694. [PMID: 29642037 DOI: 10.1016/j.bpj.2018.02.019] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 02/08/2018] [Accepted: 02/12/2018] [Indexed: 01/03/2023] Open
Abstract
Cell migration is a complex process, requiring coordination of many subcellular processes including membrane protrusion, adhesion, and contractility. For efficient cell migration, cells must concurrently control both transmission of large forces through adhesion structures and translocation of the cell body via adhesion turnover. Although mechanical regulation of protein dynamics has been proposed to play a major role in force transmission during cell migration, the key proteins and their exact roles are not completely understood. Vinculin is an adhesion protein that mediates force-sensitive processes, such as adhesion assembly under cytoskeletal load. Here, we elucidate the mechanical regulation of vinculin dynamics. Specifically, we paired measurements of vinculin loads using a Förster resonance energy transfer-based tension sensor and vinculin dynamics using fluorescence recovery after photobleaching to measure force-sensitive protein dynamics in living cells. We find that vinculin adopts a variety of mechanical states at adhesions, and the relationship between vinculin load and vinculin dynamics can be altered by the inhibition of vinculin binding to talin or actin or reduction of cytoskeletal contractility. Furthermore, the force-stabilized state of vinculin required for the stabilization of membrane protrusions is unnecessary for random migration, but is required for directional migration along a substrate-bound cue. These data show that the force-sensitive dynamics of vinculin impact force transmission and enable the mechanical integration of subcellular processes. These results suggest that the regulation of force-sensitive protein dynamics may have an underappreciated role in many cellular processes.
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Affiliation(s)
| | - David W Scott
- Lineberger Comprehensive Cancer Center, UNC Chapel, Chapel Hill, North Carolina
| | | | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, North Carolina.
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18
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TRPV4-mediated calcium signaling in mesenchymal stem cells regulates aligned collagen matrix formation and vinculin tension. Proc Natl Acad Sci U S A 2019; 116:1992-1997. [PMID: 30674675 DOI: 10.1073/pnas.1811095116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Microarchitectural cues drive aligned fibrillar collagen deposition in vivo and in biomaterial scaffolds, but the cell-signaling events that underlie this process are not well understood. Utilizing a multicellular patterning model system that allows for observation of intracellular signaling events during collagen matrix assembly, we investigated the role of calcium (Ca2+) signaling in human mesenchymal stem cells (MSCs) during this process. We observed spontaneous Ca2+ oscillations in MSCs during fibrillar collagen assembly, and hypothesized that the transient receptor potential vanilloid 4 (TRPV4) ion channel, a mechanosensitive Ca2+-permeable channel, may regulate this signaling. Inhibition of TRPV4 nearly abolished Ca2+ signaling at initial stages of collagen matrix assembly, while at later times had reduced but significant effects. Importantly, blocking TRPV4 activity dramatically reduced aligned collagen fibril assembly; conversely, activating TRPV4 accelerated aligned collagen formation. TRPV4-dependent Ca2+ oscillations were found to be independent of pattern shape or subpattern cell location, suggesting this signaling mechanism is necessary for aligned collagen formation but not sufficient in the absence of physical (microarchitectural) cues that force multicellular alignment. As cell-generated mechanical forces are known to be critical to the matrix assembly process, we examined the role of TRPV4-mediated Ca2+ signaling in force generated across the load-bearing focal adhesion protein vinculin within MSCs using an FRET-based tension sensor. Inhibiting TRPV4 decreased tensile force across vinculin, whereas TRPV4 activation caused a dynamic unloading and reloading of vinculin. Together, these findings suggest TRPV4 activity regulates forces at cell-matrix adhesions and is critical to aligned collagen matrix assembly by MSCs.
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19
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Mechanical loading of desmosomes depends on the magnitude and orientation of external stress. Nat Commun 2018; 9:5284. [PMID: 30538252 PMCID: PMC6290003 DOI: 10.1038/s41467-018-07523-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Accepted: 11/08/2018] [Indexed: 01/19/2023] Open
Abstract
Desmosomes are intercellular adhesion complexes that connect the intermediate filament cytoskeletons of neighboring cells, and are essential for the mechanical integrity of mammalian tissues. Mutations in desmosomal proteins cause severe human pathologies including epithelial blistering and heart muscle dysfunction. However, direct evidence for their load-bearing nature is lacking. Here we develop Förster resonance energy transfer (FRET)-based tension sensors to measure the forces experienced by desmoplakin, an obligate desmosomal protein that links the desmosomal plaque to intermediate filaments. Our experiments reveal that desmoplakin does not experience significant tension under most conditions, but instead becomes mechanically loaded when cells are exposed to external mechanical stresses. Stress-induced loading of desmoplakin is transient and sensitive to the magnitude and orientation of the applied tissue deformation, consistent with a stress absorbing function for desmosomes that is distinct from previously analyzed cell adhesion complexes. Desmosomes are intercellular adhesion complexes that connect the intermediate filament cytoskeletons of neighboring cells but direct evidence for their load-bearing nature is lacking. Here the authors develop FRET-based tension sensors to measure the forces experienced by desmoplakin and infer that desmosomes become mechanically loaded when cells are exposed to external mechanical stresses.
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20
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Gates EM, LaCroix AS, Rothenberg KE, Hoffman BD. Improving Quality, Reproducibility, and Usability of FRET-Based Tension Sensors. Cytometry A 2018; 95:201-213. [PMID: 30523675 DOI: 10.1002/cyto.a.23688] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 10/30/2018] [Accepted: 11/05/2018] [Indexed: 02/07/2023]
Abstract
Mechanobiology, the study of how mechanical forces affect cellular behavior, is an emerging field of study that has garnered broad and significant interest. Researchers are currently seeking to better understand how mechanical signals are transmitted, detected, and integrated at a subcellular level. One tool for addressing these questions is a Förster resonance energy transfer (FRET)-based tension sensor, which enables the measurement of molecular-scale forces across proteins based on changes in emitted light. However, the reliability and reproducibility of measurements made with these sensors has not been thoroughly examined. To address these concerns, we developed numerical methods that improve the accuracy of measurements made using sensitized emission-based imaging. To establish that FRET-based tension sensors are versatile tools that provide consistent measurements, we used these methods, and demonstrated that a vinculin tension sensor is unperturbed by cell fixation, permeabilization, and immunolabeling. This suggests FRET-based tension sensors could be coupled with a variety of immuno-fluorescent labeling techniques. Additionally, as tension sensors are frequently employed in complex biological samples where large experimental repeats may be challenging, we examined how sample size affects the uncertainty of FRET measurements. In total, this work establishes guidelines to improve FRET-based tension sensor measurements, validate novel implementations of these sensors, and ensure that results are precise and reproducible. © 2018 International Society for Advancement of Cytometry.
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Affiliation(s)
- Evan M Gates
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, 27708
| | - Andrew S LaCroix
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, 27708
| | - Katheryn E Rothenberg
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, 27708
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, North Carolina, 27708
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21
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Eldridge WJ, Hoballah J, Wax A. Molecular and biophysical analysis of apoptosis using a combined quantitative phase imaging and fluorescence resonance energy transfer microscope. JOURNAL OF BIOPHOTONICS 2018; 11:e201800126. [PMID: 29896886 DOI: 10.1002/jbio.201800126] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 06/05/2016] [Accepted: 06/06/2018] [Indexed: 05/19/2023]
Abstract
Apoptotic mechanisms are often dysregulated in cancerous phenotypes. Additionally, many anticancer treatments induce apoptosis and necrosis, and the monitoring of this apoptotic activity can allow researchers to identify therapeutic efficiency. Here, we introduce a microscope which combines quantitative phase imaging (QPI) with the ability to detect molecular events via fluorescence (or Förster) resonance energy transfer (FRET). The system was applied to study cells undergoing apoptosis to correlate the onset of apoptotic enzyme activity as observed using a FRET-based apoptosis sensor with whole cell morphological changes analyzed via QPI. The QPI data showed changes in cell disorder strength during the initiation of apoptotic enzymatic activity.
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Affiliation(s)
- Will J Eldridge
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Jawad Hoballah
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
| | - Adam Wax
- Department of Biomedical Engineering, Duke University, Durham, North Carolina
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22
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LaCroix AS, Lynch AD, Berginski ME, Hoffman BD. Tunable molecular tension sensors reveal extension-based control of vinculin loading. eLife 2018; 7:33927. [PMID: 30024378 PMCID: PMC6053308 DOI: 10.7554/elife.33927] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Accepted: 06/03/2018] [Indexed: 01/03/2023] Open
Abstract
Molecular tension sensors have contributed to a growing understanding of mechanobiology. However, the limited dynamic range and inability to specify the mechanical sensitivity of these sensors has hindered their widespread use in diverse contexts. Here, we systematically examine the components of tension sensors that can be altered to improve their functionality. Guided by the development of a first principles model describing the mechanical behavior of these sensors, we create a collection of sensors that exhibit predictable sensitivities and significantly improved performance in cellulo. Utilized in the context of vinculin mechanobiology, a trio of these new biosensors with distinct force- and extension-sensitivities reveal that an extension-based control paradigm regulates vinculin loading in a variety of mechanical contexts. To enable the rational design of molecular tension sensors appropriate for diverse applications, we predict the mechanical behavior, in terms of force and extension, of additional 1020 distinct designs. Cells must sense signals from their surroundings to play their roles within the body. These signals can be biochemical, such as growth-promoting substances, or mechanical, for example the stiffness or softness of the environment. Mechanical signals can be detected by load-bearing proteins, which stretch like tiny springs in response to forces. In animals, these proteins span the membrane separating the interior of the cell from the exterior. Externally, the proteins attach to structures around the cell; internally, they connect to the machinery that both generates forces and allows cells to respond to signals from outside. As such, load-bearing proteins form a direct mechanical link between cell and environment. Scientists use tools called molecular tension sensors to measure how much a load-bearing protein stretches in response to changes, and the force that is being applied to it. However, just like any other type of scale, these sensors only work over a certain range, which happens to be limited. This means that, for example, they cannot measure forces in tissues that are too soft (like the brain), or too stiff (such as bones). New sensors that can assess forces in these contexts are therefore needed, but so far research in this area has been slow due to a reliance on ‘trial-and-error’ approaches. Here, LaCroix et al. developed a new method to predict the sensitivity of molecular tension sensors inside cells. This was accomplished by examining several existing sensors, and identifying which components could be altered to change the properties of the sensors. Then, this information was used to create a computer model that could predict how new sensors would behave, and which range of forces they could measure. Finally, the sensors designed following this method were tested in mouse cells grown in the laboratory, and they worked better than their predecessors. The next step was for LaCroix et al. to use a trio of new sensors with different sensitivities to study the load-bearing protein vinculin in mouse cells. The goal was to figure out exactly how cells manage their load-bearing proteins. Indeed, it was widely assumed that a cell acts on a load-bearing protein by applying a force on it. In response, the protein would stretch by a certain amount, which can change depending on its properties – a ‘stiffer’ protein would stretch less. Unexpectedly, the new sensors showed that cells instead manipulate how much vinculin stretches, applying varying forces to achieve the same length of the protein in different environments. Improved molecular tension sensors will give scientists a better insight into how cells respond to their mechanical environment, which could help to direct cell behavior in tissues engineered in the laboratory. This knowledge is also directly relevant to human health, as the mechanical properties of many tissues change during disease, such as tumors stiffening during cancer.
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Affiliation(s)
- Andrew S LaCroix
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Andrew D Lynch
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Matthew E Berginski
- Department of Biomedical Engineering, Duke University, Durham, United States
| | - Brenton D Hoffman
- Department of Biomedical Engineering, Duke University, Durham, United States
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23
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Baddam SR, Arsenovic PT, Narayanan V, Duggan NR, Mayer CR, Newman ST, Abutaleb DA, Mohan A, Kowalczyk AP, Conway DE. The Desmosomal Cadherin Desmoglein-2 Experiences Mechanical Tension as Demonstrated by a FRET-Based Tension Biosensor Expressed in Living Cells. Cells 2018; 7:cells7070066. [PMID: 29949915 PMCID: PMC6070948 DOI: 10.3390/cells7070066] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Revised: 06/21/2018] [Accepted: 06/22/2018] [Indexed: 11/16/2022] Open
Abstract
Cell-cell junctions are critical structures in a number of tissues for mechanically coupling cells together, cell-to-cell signaling, and establishing a barrier. In many tissues, desmosomes are an important component of cell-cell junctions. Loss or impairment of desmosomes presents with clinical phenotypes in the heart and skin as cardiac arrhythmias and skin blistering, respectively. Because heart and skin are tissues that are subject to large mechanical stresses, we hypothesized that desmosomes, similar to adherens junctions, would also experience significant tensile loading. To directly measure mechanical forces across desmosomes, we developed and validated a desmoglein-2 (DSG-2) force sensor, using the existing TSmod Förster resonance energy transfer (FRET) force biosensor. When expressed in human cardiomyocytes, the force sensor reported high tensile loading of DSG-2 during contraction. Additionally, when expressed in Madin-Darby canine kidney (MDCK) epithelial or epidermal (A431) monolayers, the sensor also reported tensile loading. Finally, we observed higher DSG-2 forces in 3D MDCK acini when compared to 2D monolayers. Taken together, our results show that desmosomes experience low levels of mechanical tension in resting cells, with significantly higher forces during active loading.
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Affiliation(s)
- Sindora R Baddam
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Paul T Arsenovic
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Vani Narayanan
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Nicole R Duggan
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Carl R Mayer
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Shaston T Newman
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Dahlia A Abutaleb
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | - Abhinav Mohan
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
| | | | - Daniel E Conway
- Department of Biomedical Engineering, Virginia Commonwealth University, Richmond, VA 23284, USA.
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24
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Oakes PW. Balancing forces in migration. Curr Opin Cell Biol 2018; 54:43-49. [PMID: 29723736 DOI: 10.1016/j.ceb.2018.04.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 04/06/2018] [Accepted: 04/12/2018] [Indexed: 01/13/2023]
Abstract
The integrated molecular interactions of proteins can create active biological networks whose material properties and actions can impact a variety of physiological processes. Chief among these is the ability to generate and respond to physical forces. The cytoskeleton plays a key role in this behavior, characterized by active self-reorganization to control a cell's shape and mediate its physical interactions. This review discusses our current understanding of how the material properties of the cytoskeleton and its physical interactions with the extracellular environment impact cell migration.
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Affiliation(s)
- Patrick W Oakes
- Department of Physics & Astronomy, University of Rochester, Rochester, NY 14627, United States; Department of Biology, University of Rochester, Rochester, NY 14627, United States.
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25
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Win Z, Buksa JM, Steucke KE, Gant Luxton GW, Barocas VH, Alford PW. Cellular Microbiaxial Stretching to Measure a Single-Cell Strain Energy Density Function. J Biomech Eng 2018; 139:2618751. [PMID: 28397957 DOI: 10.1115/1.4036440] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Indexed: 01/02/2023]
Abstract
The stress in a cell due to extracellular mechanical stimulus is determined by its mechanical properties, and the structural organization of many adherent cells suggests that their properties are anisotropic. This anisotropy may significantly influence the cells' mechanotransductive response to complex loads, and has important implications for development of accurate models of tissue biomechanics. Standard methods for measuring cellular mechanics report linear moduli that cannot capture large-deformation anisotropic properties, which in a continuum mechanics framework are best described by a strain energy density function (SED). In tissues, the SED is most robustly measured using biaxial testing. Here, we describe a cellular microbiaxial stretching (CμBS) method that modifies this tissue-scale approach to measure the anisotropic elastic behavior of individual vascular smooth muscle cells (VSMCs) with nativelike cytoarchitecture. Using CμBS, we reveal that VSMCs are highly anisotropic under large deformations. We then characterize a Holzapfel-Gasser-Ogden type SED for individual VSMCs and find that architecture-dependent properties of the cells can be robustly described using a formulation solely based on the organization of their actin cytoskeleton. These results suggest that cellular anisotropy should be considered when developing biomechanical models, and could play an important role in cellular mechano-adaptation.
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Affiliation(s)
- Zaw Win
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail:
| | - Justin M Buksa
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail:
| | - Kerianne E Steucke
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail:
| | - G W Gant Luxton
- Department of Genetics, Cell Biology, and Development, University of Minnesota-Twin Cities, 420 Washington Avenue SE MCB 4-128, Minneapolis, MN 55455 e-mail:
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail:
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota-Twin Cities, 312 Church Street SE NHH 7-105, Minneapolis, MN 55455 e-mail:
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26
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Abstract
Mechanotransduction, or the process by which mechanical forces regulate cellular functions, is increasingly studied in a variety of different physiological and pathological contexts. Although these forces are most often studied at cell-matrix and cell-cell adhesions, recent work has shown that the nuclear LINC complex is also subject to mechanical forces. Here we describe how to use a FRET-based biosensor, known as TSmod, in the LINC complex protein nesprin-2G. This approach allows for measurement of LINC complex forces in living cells with spatial-temporal resolution.
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27
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Lunova M, Zablotskii V, Dempsey NM, Devillers T, Jirsa M, Syková E, Kubinová Š, Lunov O, Dejneka A. Modulation of collective cell behaviour by geometrical constraints. Integr Biol (Camb) 2017; 8:1099-1110. [PMID: 27738682 DOI: 10.1039/c6ib00125d] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intracellular and extracellular mechanical forces play a crucial role during tissue growth, modulating nuclear shape and function and resulting in complex collective cell behaviour. However, the mechanistic understanding of how the orientation, shape, symmetry and homogeneity of cells are affected by environmental geometry is still lacking. Here we investigate cooperative cell behaviour and patterns under geometric constraints created by topographically patterned substrates. We show how cells cooperatively adopt their geometry, shape, positioning of the nucleus and subsequent proliferation activity. Our findings indicate that geometric constraints induce significant squeezing of cells and nuclei, cytoskeleton reorganization, drastic condensation of chromatin resulting in a change in the cell proliferation rate and the anisotropic growth of cultures. Altogether, this work not only demonstrates complex non-trivial collective cellular responses to geometrical constraints but also provides a tentative explanation of the observed cell culture patterns grown on different topographically patterned substrates. These findings provide important fundamental knowledge, which could serve as a basis for better controlled tissue growth and cell-engineering applications.
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Affiliation(s)
- Mariia Lunova
- Institute for Clinical & Experimental Medicine (IKEM), Prague, Czech Republic
| | - Vitalii Zablotskii
- Institute of Physics of the Academy of Sciences of the Czech Republic, Prague, 18221, Czech Republic.
| | - Nora M Dempsey
- Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France and CNRS, Inst NEEL, F-38042 Grenoble, France
| | - Thibaut Devillers
- Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France and CNRS, Inst NEEL, F-38042 Grenoble, France
| | - Milan Jirsa
- Institute for Clinical & Experimental Medicine (IKEM), Prague, Czech Republic
| | - Eva Syková
- Institute of Experimental Medicine AS CR, Prague, Czech Republic
| | - Šárka Kubinová
- Institute of Physics of the Academy of Sciences of the Czech Republic, Prague, 18221, Czech Republic. and Institute of Experimental Medicine AS CR, Prague, Czech Republic
| | - Oleg Lunov
- Institute of Physics of the Academy of Sciences of the Czech Republic, Prague, 18221, Czech Republic.
| | - Alexandr Dejneka
- Institute of Physics of the Academy of Sciences of the Czech Republic, Prague, 18221, Czech Republic.
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28
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Nanoscale mechanobiology of cell adhesions. Semin Cell Dev Biol 2017; 71:53-67. [PMID: 28754443 DOI: 10.1016/j.semcdb.2017.07.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/17/2017] [Accepted: 07/19/2017] [Indexed: 12/16/2022]
Abstract
Proper physiological functions of cells and tissues depend upon their abilities to sense, transduce, integrate, and generate mechanical and biochemical signals. Although such mechanobiological phenomena are widely observed, the molecular mechanisms driving these outcomes are still not fully understood. Cell adhesions formed by integrins and cadherins receptors are key structures that process diverse sources of signals to elicit complex mechanobiological responses. Since the nanoscale is the length scale at which molecules interact to relay force and information, the understanding of cell adhesions at the nanoscale level is important for grasping the inner logics of cellular decision making. Until recently, the study of the biological nanoscale has been restricted by available molecular and imaging tools. Fortunately, rapid technological advances have increasingly opened up the nanoscale realm to systematic investigations. In this review, we discuss current insights and key open questions regarding the nanoscale structure and function relationship of cell adhesions, focusing on recent progresses in characterizing their composition, spatial organization, and cytomechanical operation.
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29
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Sarangi BR, Gupta M, Doss BL, Tissot N, Lam F, Mège RM, Borghi N, Ladoux B. Coordination between Intra- and Extracellular Forces Regulates Focal Adhesion Dynamics. NANO LETTERS 2017; 17:399-406. [PMID: 27990827 PMCID: PMC5423523 DOI: 10.1021/acs.nanolett.6b04364] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Focal adhesions (FAs) are important mediators of cell-substrate interactions. One of their key functions is the transmission of forces between the intracellular acto-myosin network and the substrate. However, the relationships between cell traction forces, FA architecture, and molecular forces within FAs are poorly understood. Here, by combining Förster resonance energy transfer (FRET)-based molecular force biosensors with micropillar-based traction force sensors and high-resolution fluorescence microscopy, we simultaneously map molecular tension across vinculin, a key protein in FAs, and traction forces at FAs. Our results reveal strong spatiotemporal correlations between vinculin tension and cell traction forces at FAs throughout a wide range of substrate stiffnesses. Furthermore, we find that molecular tension within individual FAs follows a biphasic distribution from the proximal (toward the cell nucleus) to distal end (toward the cell edge). Using super-resolution imaging, we show that such a distribution relates to that of FA proteins. On the basis of our experimental data, we propose a model in which FA dynamics results from tension changes along the FAs.
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Affiliation(s)
- Bibhu Ranjan Sarangi
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
- SRM Research Institute and Department of Physics & Nanotechnology, SRM University, Kattankulathur, India
| | - Mukund Gupta
- Mechanobiology Institute (MBI), National University of Singapore, Singapore
| | - Bryant L. Doss
- Mechanobiology Institute (MBI), National University of Singapore, Singapore
| | - Nicolas Tissot
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
| | - France Lam
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
| | - René-Marc Mège
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
| | - Nicolas Borghi
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
| | - Benoît Ladoux
- Institut Jacques Monod (IJM), CNRS UMR 7592 & University Paris Diderot, Paris, France
- Mechanobiology Institute (MBI), National University of Singapore, Singapore
- Corresponding Author
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30
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Freikamp A, Cost AL, Grashoff C. The Piconewton Force Awakens: Quantifying Mechanics in Cells. Trends Cell Biol 2016; 26:838-847. [DOI: 10.1016/j.tcb.2016.07.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 07/20/2016] [Accepted: 07/26/2016] [Indexed: 02/07/2023]
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31
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Freikamp A, Mehlich A, Klingner C, Grashoff C. Investigating piconewton forces in cells by FRET-based molecular force microscopy. J Struct Biol 2016; 197:37-42. [PMID: 26980477 DOI: 10.1016/j.jsb.2016.03.011] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 03/11/2016] [Accepted: 03/12/2016] [Indexed: 11/16/2022]
Abstract
The ability of cells to sense and respond to mechanical forces is crucial for a wide range of developmental and pathophysiological processes. The molecular mechanisms underlying cellular mechanotransduction, however, are largely unknown because suitable techniques to measure mechanical forces across individual molecules in cells have been missing. In this article, we highlight advances in the development of molecular force sensing techniques and discuss our recently expanded set of FRET-based tension sensors that allows the analysis of mechanical forces with piconewton sensitivity in cells. In addition, we provide a theoretical framework for the design of additional tension sensor modules with adjusted force sensitivity.
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Affiliation(s)
- Andrea Freikamp
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Alexander Mehlich
- Technical University of Munich, Physics Department E22, Garching D-85748, Germany
| | - Christoph Klingner
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany
| | - Carsten Grashoff
- Max Planck Institute of Biochemistry, Group of Molecular Mechanotransduction, Martinsried D-82152, Germany.
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