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Katsuta H, Sokabe M, Hirata H. From stress fiber to focal adhesion: a role of actin crosslinkers in force transmission. Front Cell Dev Biol 2024; 12:1444827. [PMID: 39193363 PMCID: PMC11347286 DOI: 10.3389/fcell.2024.1444827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Accepted: 08/01/2024] [Indexed: 08/29/2024] Open
Abstract
The contractile apparatus, stress fiber (SF), is connected to the cell adhesion machinery, focal adhesion (FA), at the termini of SF. The SF-FA complex is essential for various mechanical activities of cells, including cell adhesion to the extracellular matrix (ECM), ECM rigidity sensing, and cell migration. This mini-review highlights the importance of SF mechanics in these cellular activities. Actin-crosslinking proteins solidify SFs by attenuating myosin-driven flows of actin and myosin filaments within the SF. In the solidified SFs, viscous slippage between actin filaments in SFs and between the filaments and the surrounding cytosol is reduced, leading to efficient transmission of myosin-generated contractile force along the SFs. Hence, SF solidification via actin crosslinking ensures exertion of a large force to FAs, enabling FA maturation, ECM rigidity sensing and cell migration. We further discuss intracellular mechanisms for tuning crosslinker-modulated SF mechanics and the potential relationship between the aberrance of SF mechanics and pathology including cancer.
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Affiliation(s)
- Hiroki Katsuta
- Department of Cardiovascular Physiology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan
| | - Masahiro Sokabe
- Human Information Systems Laboratories, Kanazawa Institute of Technology, Hakusan, Japan
| | - Hiroaki Hirata
- Department of Applied Bioscience, Kanazawa Institute of Technology, Hakusan, Japan
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2
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Ghisleni A, Bonilla-Quintana M, Crestani M, Lavagnino Z, Galli C, Rangamani P, Gauthier NC. Mechanically induced topological transition of spectrin regulates its distribution in the mammalian cell cortex. Nat Commun 2024; 15:5711. [PMID: 38977673 PMCID: PMC11231315 DOI: 10.1038/s41467-024-49906-6] [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: 01/24/2024] [Accepted: 06/24/2024] [Indexed: 07/10/2024] Open
Abstract
The cell cortex is a dynamic assembly formed by the plasma membrane and underlying cytoskeleton. As the main determinant of cell shape, the cortex ensures its integrity during passive and active deformations by adapting cytoskeleton topologies through yet poorly understood mechanisms. The spectrin meshwork ensures such adaptation in erythrocytes and neurons by adopting different organizations. Erythrocytes rely on triangular-like lattices of spectrin tetramers, whereas in neurons they are organized in parallel, periodic arrays. Since spectrin is ubiquitously expressed, we exploited Expansion Microscopy to discover that, in fibroblasts, distinct meshwork densities co-exist. Through biophysical measurements and computational modeling, we show that the non-polarized spectrin meshwork, with the intervention of actomyosin, can dynamically transition into polarized clusters fenced by actin stress fibers that resemble periodic arrays as found in neurons. Clusters experience lower mechanical stress and turnover, despite displaying an extension close to the tetramer contour length. Our study sheds light on the adaptive properties of spectrin, which participates in the protection of the cell cortex by varying its densities in response to key mechanical features.
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Affiliation(s)
- Andrea Ghisleni
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Mayte Bonilla-Quintana
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA
| | - Michele Crestani
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy
- Laboratory of Applied Mechanobiology, Department for Health Sciences and Technology, ETH Zürich, Zürich, Switzerland
| | - Zeno Lavagnino
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy
| | - Camilla Galli
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy
- Humanitas Cardio Center, IRCCS Humanitas Research Hospital, Rozzano (Milan, Italy
| | - Padmini Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, CA, USA.
| | - Nils C Gauthier
- IFOM ETS, The AIRC Institute of Molecular Oncology, Milan, Italy.
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3
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Bonilla-Quintana M, Ghisleni A, Gauthier N, Rangamani P. Dynamic mechanisms for membrane skeleton transitions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.29.591779. [PMID: 38746295 PMCID: PMC11092671 DOI: 10.1101/2024.04.29.591779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The plasma membrane and the underlying skeleton form a protective barrier for eukaryotic cells. The molecules forming this complex composite material constantly rearrange under mechanical stress to confer this protective capacity. One of those molecules, spectrin, is ubiquitous in the membrane skeleton and primarily located proximal to the inner leaflet of the plasma membrane and engages in protein-lipid interactions via a set of membrane-anchoring domains. Spectrin is linked by short actin filaments and its conformation varies in different types of cells. In this work, we developed a generalized network model for the membrane skeleton integrated with myosin contractility and membrane mechanics to investigate the response of the spectrin meshwork to mechanical loading. We observed that the force generated by membrane bending is important to maintain a smooth skeletal structure. This suggests that the membrane is not just supported by the skeleton, but has an active contribution to the stability of the cell structure. We found that spectrin and myosin turnover are necessary for the transition between stress and rest states in the skeleton. Our model reveals that the actin-spectrin meshwork dynamics are balanced by the membrane forces with area constraint and volume restriction promoting the stability of the membrane skeleton. Furthermore, we showed that cell attachment to the substrate promotes shape stabilization. Thus, our proposed model gives insight into the shared mechanisms of the membrane skeleton associated with myosin and membrane that can be tested in different types of cells.
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Affiliation(s)
- M. Bonilla-Quintana
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla CA 92093, USA
| | - A. Ghisleni
- Institute FIRC of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy
| | - N. Gauthier
- Institute FIRC of Molecular Oncology (IFOM), Via Adamello 16, 20139, Milan, Italy
| | - P. Rangamani
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla CA 92093, USA
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4
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Elhamshari A, Elkhodary K. Proposing a Caputo-Land System for active tension. Capturing variable viscoelasticity. Heliyon 2024; 10:e26143. [PMID: 38390177 PMCID: PMC10881374 DOI: 10.1016/j.heliyon.2024.e26143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 02/08/2024] [Accepted: 02/08/2024] [Indexed: 02/24/2024] Open
Abstract
Accurate cell-level active tension modeling for cardiomyocytes is critical to understanding cardiac functionality on a subject-specific basis. However, cell-level models in the literature fail to account for viscoelasticity and inter-subject variations in active tension, which are relevant to disease diagnostics and drug screening, e.g., for cardiotoxicity. Thus, we propose a fractional order system to model cell-level active tension by extending Land's state-of-the-art model of cardiac contraction. Our approach features the (left) Caputo derivative of six state variables that identify the mechanistic origins of viscoelasticity in a myocardial cell in terms of the thin filament, thick filament, and length-dependent interactions. This proposed CLS is the first of its kind for active tension modeling in cells and demonstrates notable subject-specificity, with smaller mean square errors than the reference model relative to cell-level experiments across subjects, promising greater clinical relevance than its counterparts in the literature by highlighting the contribution of different cellular mechanisms to apparent viscoelastic cell behavior, and how it could vary with disease.
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Affiliation(s)
- Afnan Elhamshari
- The Robotics, Control, and Smart Systems Program, The American University in Cairo, 11835, New Cairo, Egypt
| | - Khalil Elkhodary
- The Department of Mechanical Engineering, The American University in Cairo, 11835, New Cairo, Egypt
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5
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Ghisleni A, Bonilla-Quintana M, Crestani M, Fukuzawa A, Rangamani P, Gauthier N. Mechanically induced topological transition of spectrin regulates its distribution in the mammalian cortex. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.02.522381. [PMID: 36712133 PMCID: PMC9881866 DOI: 10.1101/2023.01.02.522381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The cell cortex is a dynamic assembly that ensures cell integrity during passive deformation or active response by adapting cytoskeleton topologies with poorly understood mechanisms. The spectrin meshwork ensures such adaptation in erythrocytes and neurons. Erythrocytes rely on triangular-like lattices of spectrin tetramers, which in neurons are organized in periodic arrays. We exploited Expansion Microscopy to discover that these two distinct topologies can co-exist in other mammalian cells such as fibroblasts. We show through biophysical measurements and computational modeling that spectrin provides coverage of the cortex and, with the intervention of actomyosin, erythroid-like lattices can dynamically transition into condensates resembling neuron-like periodic arrays fenced by actin stress fibers. Spectrin condensates experience lower mechanical stress and turnover despite displaying an extension close to the contour length of the tetramer. Our study sheds light on the adaptive properties of spectrin, which ensures protection of the cortex by undergoing mechanically induced topological transitions.
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6
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The role of the dystrophin glycoprotein complex in muscle cell mechanotransduction. Commun Biol 2022; 5:1022. [PMID: 36168044 PMCID: PMC9515174 DOI: 10.1038/s42003-022-03980-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 09/12/2022] [Indexed: 11/09/2022] Open
Abstract
Dystrophin is the central protein of the dystrophin-glycoprotein complex (DGC) in skeletal and heart muscle cells. Dystrophin connects the actin cytoskeleton to the extracellular matrix (ECM). Severing the link between the ECM and the intracellular cytoskeleton has a devastating impact on the homeostasis of skeletal muscle cells, leading to a range of muscular dystrophies. In addition, the loss of a functional DGC leads to progressive dilated cardiomyopathy and premature death. Dystrophin functions as a molecular spring and the DGC plays a critical role in maintaining the integrity of the sarcolemma. Additionally, evidence is accumulating, linking the DGC to mechanosignalling, albeit this role is still less understood. This review article aims at providing an up-to-date perspective on the DGC and its role in mechanotransduction. We first discuss the intricate relationship between muscle cell mechanics and function, before examining the recent research for a role of the dystrophin glycoprotein complex in mechanotransduction and maintaining the biomechanical integrity of muscle cells. Finally, we review the current literature to map out how DGC signalling intersects with mechanical signalling pathways to highlight potential future points of intervention, especially with a focus on cardiomyopathies. A review of the function of the Dystrophic Glycoprotein Complex (DGC) in mechanosignaling provides an overview of the various components of DGC and potential mechanopathogenic mechanisms, particularly as they relate to muscular dystrophy.
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7
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Jasnin M, Hervy J, Balor S, Bouissou A, Proag A, Voituriez R, Schneider J, Mangeat T, Maridonneau-Parini I, Baumeister W, Dmitrieff S, Poincloux R. Elasticity of podosome actin networks produces nanonewton protrusive forces. Nat Commun 2022; 13:3842. [PMID: 35789161 PMCID: PMC9253342 DOI: 10.1038/s41467-022-30652-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/10/2022] [Indexed: 11/26/2022] Open
Abstract
Actin filaments assemble into force-generating systems involved in diverse cellular functions, including cell motility, adhesion, contractility and division. It remains unclear how networks of actin filaments, which individually generate piconewton forces, can produce forces reaching tens of nanonewtons. Here we use in situ cryo-electron tomography to unveil how the nanoscale architecture of macrophage podosomes enables basal membrane protrusion. We show that the sum of the actin polymerization forces at the membrane is not sufficient to explain podosome protrusive forces. Quantitative analysis of podosome organization demonstrates that the core is composed of a dense network of bent actin filaments storing elastic energy. Theoretical modelling of the network as a spring-loaded elastic material reveals that it exerts forces of a few tens of nanonewtons, in a range similar to that evaluated experimentally. Thus, taking into account not only the interface with the membrane but also the bulk of the network, is crucial to understand force generation by actin machineries. Our integrative approach sheds light on the elastic behavior of dense actin networks and opens new avenues to understand force production inside cells.
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Affiliation(s)
- Marion Jasnin
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | - Jordan Hervy
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France
| | - Stéphanie Balor
- Plateforme de Microscopie Électronique Intégrative, Centre de Biologie Intégrative, CNRS, UPS, Toulouse, France
| | - Anaïs Bouissou
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Amsha Proag
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France
| | | | - Jonathan Schneider
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Thomas Mangeat
- LITC Core Facility, Centre de Biologie Integrative, Université de Toulouse, CNRS, UPS, 31062, Toulouse, France
| | | | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Serge Dmitrieff
- Université de Paris, CNRS, Institut Jacques Monod, Paris, France.
| | - Renaud Poincloux
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Toulouse, France.
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8
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Abstract
The brain harbors a unique ability to, figuratively speaking, shift its gears. During wakefulness, the brain is geared fully toward processing information and behaving, while homeostatic functions predominate during sleep. The blood-brain barrier establishes a stable environment that is optimal for neuronal function, yet the barrier imposes a physiological problem; transcapillary filtration that forms extracellular fluid in other organs is reduced to a minimum in brain. Consequently, the brain depends on a special fluid [the cerebrospinal fluid (CSF)] that is flushed into brain along the unique perivascular spaces created by astrocytic vascular endfeet. We describe this pathway, coined the term glymphatic system, based on its dependency on astrocytic vascular endfeet and their adluminal expression of aquaporin-4 water channels facing toward CSF-filled perivascular spaces. Glymphatic clearance of potentially harmful metabolic or protein waste products, such as amyloid-β, is primarily active during sleep, when its physiological drivers, the cardiac cycle, respiration, and slow vasomotion, together efficiently propel CSF inflow along periarterial spaces. The brain's extracellular space contains an abundance of proteoglycans and hyaluronan, which provide a low-resistance hydraulic conduit that rapidly can expand and shrink during the sleep-wake cycle. We describe this unique fluid system of the brain, which meets the brain's requisites to maintain homeostasis similar to peripheral organs, considering the blood-brain-barrier and the paths for formation and egress of the CSF.
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Affiliation(s)
- Martin Kaag Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
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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: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 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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Affiliation(s)
- Claudia Tanja Mierke
- Faculty of Physics and Earth Science, Peter Debye Institute of Soft Matter Physics, Biological Physics Division, University of Leipzig, Leipzig, Germany
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10
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Zhou L, Feng S, Li L, Lü S, Zhang Y, Long M. Two Complementary Signaling Pathways Depict Eukaryotic Chemotaxis: A Mechanochemical Coupling Model. Front Cell Dev Biol 2021; 9:786254. [PMID: 34869388 PMCID: PMC8635958 DOI: 10.3389/fcell.2021.786254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 10/21/2021] [Indexed: 01/16/2023] Open
Abstract
Many eukaryotic cells, including neutrophils and Dictyostelium cells, are able to undergo correlated random migration in the absence of directional cues while reacting to shallow gradients of chemoattractants with exquisite precision. Although progress has been made with regard to molecular identities, it remains elusive how molecular mechanics are integrated with cell mechanics to initiate and manipulate cell motility. Here, we propose a two dimensional (2D) cell migration model wherein a multilayered dynamic seesaw mechanism is accompanied by a mechanical strain-based inhibition mechanism. In biology, these two mechanisms can be mapped onto the biochemical feedback between phosphoinositides (PIs) and Rho GTPase and the mechanical interplay between filamin A (FLNa) and FilGAP. Cell migration and the accompanying morphological changes are demonstrated in numerical simulations using a particle-spring model, and the diffusion in the cell membrane are simulations using a one dimensional (1D) finite differences method (FDM). The fine balance established between endogenous signaling and a mechanically governed inactivation scheme ensures the endogenous cycle of self-organizing pseudopods, accounting for the correlated random migration. Furthermore, this model cell manifests directional and adaptable responses to shallow graded signaling, depending on the overwhelming effect of the graded stimuli guidance on strain-based inhibition. Finally, the model cell becomes trapped within an obstacle-ridden spatial region, manifesting a shuttle run for local explorations and can chemotactically “escape”, illustrating again the balance required in the complementary signaling pathways.
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Affiliation(s)
- Lüwen Zhou
- Smart Materials and Advanced Structure Laboratory, School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo Zhejiang, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Center for Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
| | - Shiliang Feng
- Smart Materials and Advanced Structure Laboratory, School of Mechanical Engineering and Mechanics, Ningbo University, Ningbo Zhejiang, China.,Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Center for Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
| | - Long Li
- State Key Laboratory of Nonlinear Mechanics (LNM) and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China
| | - Shouqin Lü
- Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Center for Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Yan Zhang
- Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Center for Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
| | - Mian Long
- Key Laboratory of Microgravity (National Microgravity Laboratory), and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Center for Biomechanics and Bioengineering, Institute of Mechanics, Chinese Academy of Sciences, Beijing, China.,School of Engineering Science, University of Chinese Academy of Sciences, Beijing, China
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11
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Metsiou DN, Kozaniti FK, Deligianni DD. Engineering Breast Cancer Cells and hUMSCs Microenvironment in 2D and 3D Scaffolds: A Mechanical Study Approach of Stem Cells in Anticancer Therapy. Bioengineering (Basel) 2021; 8:bioengineering8110189. [PMID: 34821755 PMCID: PMC8615245 DOI: 10.3390/bioengineering8110189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 11/12/2021] [Accepted: 11/17/2021] [Indexed: 12/26/2022] Open
Abstract
Cell biomechanics plays a major role as a promising biomarker for early cancer diagnosis and prognosis. In the present study, alterations in modulus of elasticity, cell membrane roughness, and migratory potential of MCF-7 (ER+) and SKBR-3 (HER2+) cancer cells were elucidated prior to and post treatment with conditioned medium from human umbilical mesenchymal stem cells (hUMSCs-CM) during static and dynamic cell culture. Moreover, the therapeutic potency of hUMSCs-CM on cancer cell’s viability, migratory potential, and F-actin quantified intensity was addressed in 2D surfaces and 3D scaffolds. Interestingly, alterations in ER+ cancer cells showed a positive effect of treatment upon limiting cell viability, motility, and potential for migration. Moreover, increased post treatment cell stiffness indicated rigid cancer cells with confined cell movement and cytoskeletal alterations with restricted lamellipodia formation, which enhanced these results. On the contrary, the cell viability and the migratory potential were not confined post treatment with hUMSCs-CM on HER2+ cells, possibly due to their intrinsic aggressiveness. The increased post treatment cell viability and the decreased cell stiffness indicated an increased potency for cell movement. Hence, the therapy had no efficacy on HER2+ cells.
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12
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Quantifying force transmission through fibroblasts: changes of traction forces under external shearing. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 51:157-169. [PMID: 34713316 PMCID: PMC8964583 DOI: 10.1007/s00249-021-01576-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 10/06/2021] [Accepted: 10/10/2021] [Indexed: 11/17/2022]
Abstract
Mammalian cells have evolved complex mechanical connections to their microenvironment, including focal adhesion clusters that physically connect the cytoskeleton and the extracellular matrix. This mechanical link is also part of the cellular machinery to transduce, sense and respond to external forces. Although methods to measure cell attachment and cellular traction forces are well established, these are not capable of quantifying force transmission through the cell body to adhesion sites. We here present a novel approach to quantify intracellular force transmission by combining microneedle shearing at the apical cell surface with traction force microscopy at the basal cell surface. The change of traction forces exerted by fibroblasts to underlying polyacrylamide substrates as a response to a known shear force exerted with a calibrated microneedle reveals that cells redistribute forces dynamically under external shearing and during sequential rupture of their adhesion sites. Our quantitative results demonstrate a transition from dipolar to monopolar traction patterns, an inhomogeneous distribution of the external shear force to the adhesion sites as well as dynamical changes in force loading prior to and after the rupture of single adhesion sites. Our strategy of combining traction force microscopy with external force application opens new perspectives for future studies of force transmission and mechanotransduction in cells.
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13
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Shatkin G, Yeoman B, Birmingham K, Katira P, Engler AJ. Computational models of migration modes improve our understanding of metastasis. APL Bioeng 2020; 4:041505. [PMID: 33195959 PMCID: PMC7647620 DOI: 10.1063/5.0023748] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/23/2020] [Indexed: 01/07/2023] Open
Abstract
Tumor cells migrate through changing microenvironments of diseased and healthy tissue, making their migration particularly challenging to describe. To better understand this process, computational models have been developed for both the ameboid and mesenchymal modes of cell migration. Here, we review various approaches that have been used to account for the physical environment's effect on cell migration in computational models, with a focus on their application to understanding cancer metastasis and the related phenomenon of durotaxis. We then discuss how mesenchymal migration models typically simulate complex cell–extracellular matrix (ECM) interactions, while ameboid migration models use a cell-focused approach that largely ignores ECM when not acting as a physical barrier. This approach greatly simplifies or ignores the mechanosensing ability of ameboid migrating cells and should be reevaluated in future models. We conclude by describing future model elements that have not been included to date but would enhance model accuracy.
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Affiliation(s)
- Gabriel Shatkin
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA
| | | | - Katherine Birmingham
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, USA
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14
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A Stochastic Modelling Framework for Single Cell Migration: Coupling Contractility and Focal Adhesions. Symmetry (Basel) 2020. [DOI: 10.3390/sym12081348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The interaction of the actin cytoskeleton with cell–substrate adhesions is necessary for cell migration. While the trajectories of motile cells have a stochastic character, investigations of cell motility mechanisms rarely elaborate on the origins of the observed randomness. Here, guided by a few fundamental attributes of cell motility, I construct a minimal stochastic cell migration model from ground-up. The resulting model couples a deterministic actomyosin contractility mechanism with stochastic cell–substrate adhesion kinetics, and yields a well-defined piecewise deterministic process. Numerical simulations reproduce several experimentally observed results, including anomalous diffusion, tactic migration and contact guidance. This work provides a basis for the development of cell–cell collision and population migration models.
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15
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Barriga EH, Mayor R. Adjustable viscoelasticity allows for efficient collective cell migration. Semin Cell Dev Biol 2019; 93:55-68. [PMID: 29859995 PMCID: PMC6854469 DOI: 10.1016/j.semcdb.2018.05.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 05/29/2018] [Accepted: 05/30/2018] [Indexed: 12/22/2022]
Abstract
Cell migration is essential for a wide range of biological processes such as embryo morphogenesis, wound healing, regeneration, and also in pathological conditions, such as cancer. In such contexts, cells are required to migrate as individual entities or as highly coordinated collectives, both of which requiring cells to respond to molecular and mechanical cues from their environment. However, whilst the function of chemical cues in cell migration is comparatively well understood, the role of tissue mechanics on cell migration is just starting to be studied. Recent studies suggest that the dynamic tuning of the viscoelasticity within a migratory cluster of cells, and the adequate elastic properties of its surrounding tissues, are essential to allow efficient collective cell migration in vivo. In this review we focus on the role of viscoelasticity in the control of collective cell migration in various cellular systems, mentioning briefly some aspects of single cell migration. We aim to provide details on how viscoelasticity of collectively migrating groups of cells and their surroundings is adjusted to ensure correct morphogenesis, wound healing, and metastasis. Finally, we attempt to show that environmental viscoelasticity triggers molecular changes within migrating clusters and that these new molecular setups modify clusters' viscoelasticity, ultimately allowing them to migrate across the challenging geometries of their microenvironment.
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Affiliation(s)
- Elias H Barriga
- Department of Cell and Developmental Biology, University College London, WC1E 6BT, London, UK
| | - Roberto Mayor
- Department of Cell and Developmental Biology, University College London, WC1E 6BT, London, UK.
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16
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Rezaee N, Tafazzoli-Shadpour M, Haghighipour N. Effect of equiaxial cyclic strain on cardiomyogenic induction in mesenchymal stem cells. Prog Biomater 2018; 7:279-288. [PMID: 30367393 PMCID: PMC6304178 DOI: 10.1007/s40204-018-0102-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 10/18/2018] [Indexed: 10/28/2022] Open
Abstract
Differentiation of stem cells and functionality of target cells are regulated by microenvironmental stimuli to which the cells are exposed. Chemical agents such as growth factors and physical parameters including mechanical loadings are among major stimuli. In this study, equiaxial cyclic strain with two amplitudes was applied on rat adipose-derived mesenchymal stem cells (rAMSCs) with or without 5-azacytidine. The mRNA expression of cardiac-related genes was investigated through RT-PCR (polymerase chain reaction) method. Moreover, morphological features and the actin structure of the cells were studied. Results were indications of significant increase in mRNA expression among four target genes, which marked the increase in two principal cardiac markers of GATA4 and α-cardiac actin, and lesser increase in two other genes (NKX2-5, βMHC) in all experimental groups treated chemically and/or mechanically. Such effect was maximal when both treatments were applied describing the synergistic effect of combined stimuli. All treatments caused significant increase in cell area and cell shape index. The well spreading of cells was accompanied by enhanced actin structure, especially among samples subjected to mechanical stimulus. Both effects were among required features for functional muscle cells such as cardiac cells. It was concluded that the cyclic equiaxial strain enhanced cardiomyogenic induction among rat adipose-derived mesenchymal stem cells and such effect was strengthened when it was accompanied by application of chemical factor. Results can be considered among strategies for cardiomyogenic differentiation and can be employed in cardiac tissue engineering for production of functional cardiomyocytes to repair of damaged myocardium.
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Affiliation(s)
- Nasim Rezaee
- Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran, Iran
| | - Mohammad Tafazzoli-Shadpour
- Cardiovascular Engineering Lab, Faculty of Biomedical Engineering, Amirkabir University of Technology, 424 Hafez Ave, Tehran, Iran
| | - Nooshin Haghighipour
- National Cell Bank of Iran, Pasteur Institute of Iran, 69 Pasteur Ave, P.O. Box: 1316943551, Tehran, Iran
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17
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Papadopoulos P, Pinchasik BE, Tress M, Vollmer D, Kappl M, Butt HJ. Wetting of soft superhydrophobic micropillar arrays. SOFT MATTER 2018; 14:7429-7434. [PMID: 30183043 PMCID: PMC6192145 DOI: 10.1039/c8sm01333k] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Accepted: 08/24/2018] [Indexed: 05/26/2023]
Abstract
Superhydrophobic surfaces are usually assumed to be rigid so that liquids do not deform them. Here we analyze how the relation between microstructure and wetting changes when the surface is flexible. Therefore we deposited liquid drops on arrays of flexible micropillars. We imaged the drop's surface and the bending of micropillars with confocal microscopy and analyzed the deflection of micropillars while the contact line advanced and receded. The deflection is directly proportional to the horizontal component of the capillary force acting on that particular micropillar. In the Cassie or "fakir" state, drops advance by touching down on the next top faces of micropillars, much like on rigid arrays. In contrast, on the receding side the micropillars deform. The main force hindering the slide of a drop is due to pinning at the receding side, while the force on the advancing side is negligible. In the Wenzel state, micropillars were deflected in both receding and advancing states.
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Affiliation(s)
| | | | - Martin Tress
- Department of Chemistry, University of Tennessee, Knoxville, TN, USA
| | - Doris Vollmer
- Max Planck Institute for Polymer Research, Mainz, Germany.
| | - Michael Kappl
- Max Planck Institute for Polymer Research, Mainz, Germany.
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18
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Basu S, Sutradhar S, Paul R. Substrate stiffness and mechanical stress due to intercellular cooperativity guides tissue structure. J Theor Biol 2018; 457:124-136. [PMID: 30144408 DOI: 10.1016/j.jtbi.2018.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 07/30/2018] [Accepted: 08/01/2018] [Indexed: 12/31/2022]
Abstract
A key challenge in cell and tissue morphogenesis is to understand how a crucial balance between cell proliferation and apoptosis maintains an evolving tissue structure. These processes are mutually non-exclusive and require stiffness monitoring of the host substrate. Adhered cells actively mechanosense the tension in the extracellular matrix (ECM). They collectively alter self-organization and generate a host of tissue patterns. Using an in silico elastic fiber-network in two dimensions, we simulate cell-ECM composite structures and characterize features of the emerging tissue patterns during successive cell proliferation and apoptosis. Our data reveals that, in general, cell viability is a function of the cell-induced effective ECM stiffness supported by intercellular cooperativity. Translating this into a remodeling tissue, we find that average cell cycle duration in concert with the locally stressed regions of the ECM promote heterogeneous proliferation and apoptosis inducing finger-like protrusions along the tissue periphery - a feature normally observed during tumorigenesis. Further, we find that recovery of a scratch wound is delayed for cells harbored on a compliant or (and) in a highly collagen depleted ECM.
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Affiliation(s)
- S Basu
- Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, West Bengal 700032, India.
| | - S Sutradhar
- Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, West Bengal 700032, India; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA.
| | - R Paul
- Department of Solid State Physics, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Kolkata, West Bengal 700032, India.
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19
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Zhou Y, Li H, Zhang W, Xu J, Li X, Ji B. Automatic directional analysis of cell fluorescence images and morphological modeling of microfilaments. Med Biol Eng Comput 2018; 57:325-337. [PMID: 30117068 DOI: 10.1007/s11517-018-1871-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2017] [Accepted: 06/15/2018] [Indexed: 11/25/2022]
Abstract
Cytoskeleton and nucleus are two important anatomic components in eukaryotic cells. Cell fluorescence images are employed to study their realignment and deformation during cell extrusion. Quantitative analysis and modeling of cell orientation are investigated in this paper. For orientation measurement, alignment orientation of microfilaments is calculated using structure tensor method. Nuclei is segmented and fitted to ellipses in nuclei images. Based on the fitted ellipse, orientation and aspect ratio of each nucleus are computed. A morphological model is proposed to describe the movement of microfilaments quantitatively. The parameters of the model are determined by in-plane stresses obtained by numerical simulation. The proposed automatic orientation measurement algorithms can help to analyze the relationship between cell orientation and stress qualitatively. The proposed morphological model is the first model to quantitatively describe the relationship of microfilament movement with stress. Experimental results show that cell and nucleus tend to align along in-plane maximum shear stress and the proposed morphological model is a reasonable model for cell movement. The modeling of cell behavior under different stress can facilitate biomedical research such as tissue engineering and cancer analysis. Graphical abstract ᅟ.
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Affiliation(s)
- Yue Zhou
- School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081, China
| | - Huiqi Li
- School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081, China.
| | - Wanjun Zhang
- School of Information and Electronics, Beijing Institute of Technology, Beijing, 100081, China
| | - Jiayi Xu
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Xiaojun Li
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Baohua Ji
- School of Aerospace Engineering, Beijing Institute of Technology, Beijing, 100081, China
- Department of Engineering Mechanics, Zhejiang University, Zhejiang, 310027, China
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20
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TARFULEA NICOLETA. A DISCRETE MATHEMATICAL MODEL FOR SINGLE AND COLLECTIVE MOVEMENT IN AMOEBOID CELLS. J BIOL SYST 2018. [DOI: 10.1142/s0218339018500134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper, we develop a new discrete mathematical model for individual and collective cell motility. We introduce a mechanical model for the movement of a cell on a two-dimensional rigid surface to describe and investigate the cell–cell and cell–substrate interactions. The cell cytoskeleton is modeled as a series of springs and dashpots connected in parallel. The cell–substrate attachments and the cell protrusions are also included. In particular, this model is used to describe the directed movement of endothelial cells on a Matrigel plate. We compare the results from our model with experimental data. We show that cell density and substrate rigidity play an important role in network formation.
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Affiliation(s)
- NICOLETA TARFULEA
- Department of Mathematics, Purdue University Northwest, 2200 169th Street, Hammond, Indiana 46323, USA
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21
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Random Motion of Chromatin Is Influenced by Lamin A Interconnections. Biophys J 2018; 114:2465-2472. [PMID: 29759373 DOI: 10.1016/j.bpj.2018.04.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/11/2018] [Accepted: 04/19/2018] [Indexed: 01/30/2023] Open
Abstract
Using fluorescence correlation spectroscopy in single-plane illumination microscopy, we investigated the dynamics of chromatin in interphase mouse adult fibroblast cell nuclei under the influence of the intermediate filament protein lamin A. We find that 1) lamin A-eGFP and histone H2A-mRFP show significant comobility, indicating that their motions are clearly interconnected in the nucleus, and 2) that the random motion of histones H2A within the chromatin network is subdiffusive, i.e., the effective diffusion coefficient decreases for slow timescales. Knocking out lamin A changes the diffusion back to normal. Thus, lamin A influences the dynamics of the entire chromatin network. Our conclusion is that lamin A plays a central role in determining the viscoelasticity of the chromatin network and helping to maintain local ordering of interphase chromosomes.
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22
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Cheng B, Lin M, Huang G, Li Y, Ji B, Genin GM, Deshpande VS, Lu TJ, Xu F. Cellular mechanosensing of the biophysical microenvironment: A review of mathematical models of biophysical regulation of cell responses. Phys Life Rev 2017; 22-23:88-119. [PMID: 28688729 PMCID: PMC5712490 DOI: 10.1016/j.plrev.2017.06.016] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 06/14/2017] [Indexed: 12/11/2022]
Abstract
Cells in vivo reside within complex microenvironments composed of both biochemical and biophysical cues. The dynamic feedback between cells and their microenvironments hinges upon biophysical cues that regulate critical cellular behaviors. Understanding this regulation from sensing to reaction to feedback is therefore critical, and a large effort is afoot to identify and mathematically model the fundamental mechanobiological mechanisms underlying this regulation. This review provides a critical perspective on recent progress in mathematical models for the responses of cells to the biophysical cues in their microenvironments, including dynamic strain, osmotic shock, fluid shear stress, mechanical force, matrix rigidity, porosity, and matrix shape. The review highlights key successes and failings of existing models, and discusses future opportunities and challenges in the field.
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Affiliation(s)
- Bo Cheng
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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
| | - Min Lin
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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
| | - Guoyou Huang
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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
| | - Yuhui Li
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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
| | - Baohua Ji
- Biomechanics and Biomaterials Laboratory, Department of Applied Mechanics, Beijing Institute of Technology, Beijing, China
| | - Guy M Genin
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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; Department of Mechanical Engineering & Materials Science, and NSF Science and Technology Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis 63130, MO, USA
| | - Vikram S Deshpande
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom
| | - Tian Jian Lu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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
| | - Feng Xu
- The Key Laboratory of Biomedical Information Engineering of Ministry of Education, 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.
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23
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Jiang N, Bailey ME, Burke J, Ross JL, Dima RI. Modeling the effects of lattice defects on microtubule breaking and healing. Cytoskeleton (Hoboken) 2017; 74:3-17. [PMID: 27935245 DOI: 10.1002/cm.21346] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 11/29/2016] [Accepted: 11/29/2016] [Indexed: 12/19/2022]
Abstract
Microtubule reorganization often results from the loss of polymer induced through breakage or active destruction by energy-using enzymes. Pre-existing defects in the microtubule lattice likely lower structural integrity and aid filament destruction. Using large-scale molecular simulations, we model diverse microtubule fragments under forces generated at specific positions to locally crush the filament. We show that lattices with 2% defects are crushed and severed by forces three times smaller than defect-free ones. We validate our results with direct comparisons of microtubule kinking angles during severing. We find a high statistical correlation between the angle distributions from experiments and simulations indicating that they sample the same population of structures. Our simulations also indicate that the mechanical environment of the filament affects breaking: local mechanical support inhibits healing after severing, especially in the case of filaments with defects. These results recall reports of microtubule healing after flow-induced bending and corroborate prior experimental studies that show severing is more likely at locations where microtubules crossover in networks. Our results shed new light on mechanisms underlying the ability of microtubules to be destroyed and healed in the cell, either by external forces or by severing enzymes wedging dimers apart. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Nan Jiang
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, 45221
| | - Megan E Bailey
- Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst, Amherst, Massachusetts, 01003
| | - Jessica Burke
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, 45221
| | - Jennifer L Ross
- Molecular and Cellular Biology Graduate Program, University of Massachusetts Amherst, Amherst, Massachusetts, 01003.,Department of Physics, University of Massachusetts Amherst, Amherst, Massachusetts, 01003
| | - Ruxandra I Dima
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio, 45221
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24
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Zhang Y, Liao K, Li C, Lai ACK, Foo JJ, Chan V. Progress in Integrative Biomaterial Systems to Approach Three-Dimensional Cell Mechanotransduction. Bioengineering (Basel) 2017; 4:E72. [PMID: 28952551 PMCID: PMC5615318 DOI: 10.3390/bioengineering4030072] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 08/19/2017] [Accepted: 08/22/2017] [Indexed: 11/16/2022] Open
Abstract
Mechanotransduction between cells and the extracellular matrix regulates major cellular functions in physiological and pathological situations. The effect of mechanical cues on biochemical signaling triggered by cell-matrix and cell-cell interactions on model biomimetic surfaces has been extensively investigated by a combination of fabrication, biophysical, and biological methods. To simulate the in vivo physiological microenvironment in vitro, three dimensional (3D) microstructures with tailored bio-functionality have been fabricated on substrates of various materials. However, less attention has been paid to the design of 3D biomaterial systems with geometric variances, such as the possession of precise micro-features and/or bio-sensing elements for probing the mechanical responses of cells to the external microenvironment. Such precisely engineered 3D model experimental platforms pave the way for studying the mechanotransduction of multicellular aggregates under controlled geometric and mechanical parameters. Concurrently with the progress in 3D biomaterial fabrication, cell traction force microscopy (CTFM) developed in the field of cell biophysics has emerged as a highly sensitive technique for probing the mechanical stresses exerted by cells onto the opposing deformable surface. In the current work, we first review the recent advances in the fabrication of 3D micropatterned biomaterials which enable the seamless integration with experimental cell mechanics in a controlled 3D microenvironment. Then, we discuss the role of collective cell-cell interactions in the mechanotransduction of engineered tissue equivalents determined by such integrative biomaterial systems under simulated physiological conditions.
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Affiliation(s)
- Ying Zhang
- Department of Chemical Engineering, Khalifa University, Abu Dhabi 127788, UAE.
| | - Kin Liao
- Department of Aerospace Engineering, Khalifa University, Abu Dhabi 127788, UAE.
| | - Chuan Li
- Department of Biomedical Engineering, National Yang Ming University, Taipei 11221, Taiwan.
| | - Alvin C K Lai
- Department of Architecture and Civil Engineering, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
| | - Ji-Jinn Foo
- School of Engineering, Monash University Malaysia, Jalan Lagoon Selatan, 46150 Bandar Sunway, Selangor, Malaysia.
| | - Vincent Chan
- Department of Chemical Engineering, Khalifa University, Abu Dhabi 127788, UAE.
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25
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Albert PJ, Schwarz US. Modeling cell shape and dynamics on micropatterns. Cell Adh Migr 2016; 10:516-528. [PMID: 26838278 PMCID: PMC5079397 DOI: 10.1080/19336918.2016.1148864] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 01/26/2016] [Indexed: 12/29/2022] Open
Abstract
Adhesive micropatterns have become a standard tool to study cells under defined conditions. Applications range from controlling the differentiation and fate of single cells to guiding the collective migration of cell sheets. In long-term experiments, single cell normalization is challenged by cell division. For all of these setups, mathematical models predicting cell shape and dynamics can guide pattern design. Here we review recent advances in predicting and explaining cell shape, traction forces and dynamics on micropatterns. Starting with contour models as the simplest approach to explain concave cell shapes, we move on to network and continuum descriptions as examples for static models. To describe dynamic processes, cellular Potts, vertex and phase field models can be used. Different types of model are appropriate to address different biological questions and together, they provide a versatile tool box to predict cell behavior on micropatterns.
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Affiliation(s)
- Philipp J. Albert
- Institute for Theoretical Physics and BioQuant, Heidelberg University, Heidelberg, Germany
| | - Ulrich S. Schwarz
- Institute for Theoretical Physics and BioQuant, Heidelberg University, Heidelberg, Germany
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26
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Cell shape dynamics reveal balance of elasticity and contractility in peripheral arcs. Biophys J 2016; 108:2437-2447. [PMID: 25992722 DOI: 10.1016/j.bpj.2015.04.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Revised: 02/11/2015] [Accepted: 04/01/2015] [Indexed: 01/04/2023] Open
Abstract
The mechanical interaction between adherent cells and their substrate relies on the formation of adhesion sites and on the stabilization of contractile acto-myosin bundles, or stress fibers. The shape of the cell and the orientation of these fibers can be controlled by adhesive patterning. On nonadhesive gaps, fibroblasts develop thick peripheral stress fibers, with a concave curvature. The radius of curvature of these arcs results from the balance of the line tension in the arc and of the surface tension in the cell bulk. However, the nature of these forces, and in particular the contribution of myosin-dependent contractility, is not clear. To get insight into the force balance, we inhibit myosin activity and simultaneously monitor the dynamics of peripheral arc radii and traction forces. We use these measurements to estimate line and surface tension. We found that myosin inhibition led to a decrease in the traction forces and an increase in arc radius, indicating that both line tension and surface tension dropped, but the line tension decreased to a lesser extent than surface tension. These results suggest that myosin-independent force contributes to tension in the peripheral arcs. We propose a simple physical model in which the peripheral arc line tension is due to the combination of myosin II contractility and a passive elastic component, while surface tension is largely due to active contractility. Numerical solutions of this model reproduce well the experimental data and allow estimation of the contributions of elasticity and contractility to the arc line tension.
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27
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Banerjee N, Park J. Modeling and simulation of biopolymer networks: Classification of the cytoskeleton models according to multiple scales. KOREAN J CHEM ENG 2015. [DOI: 10.1007/s11814-015-0071-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Oakes PW, Banerjee S, Marchetti MC, Gardel ML. Geometry regulates traction stresses in adherent cells. Biophys J 2015; 107:825-33. [PMID: 25140417 DOI: 10.1016/j.bpj.2014.06.045] [Citation(s) in RCA: 161] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 06/10/2014] [Accepted: 06/18/2014] [Indexed: 01/08/2023] Open
Abstract
Cells generate mechanical stresses via the action of myosin motors on the actin cytoskeleton. Although the molecular origin of force generation is well understood, we currently lack an understanding of the regulation of force transmission at cellular length scales. Here, using 3T3 fibroblasts, we experimentally decouple the effects of substrate stiffness, focal adhesion density, and cell morphology to show that the total amount of work a cell does against the substrate to which it is adhered is regulated by the cell spread area alone. Surprisingly, the number of focal adhesions and the substrate stiffness have little effect on regulating the work done on the substrate by the cell. For a given spread area, the local curvature along the cell edge regulates the distribution and magnitude of traction stresses to maintain a constant strain energy. A physical model of the adherent cell as a contractile gel under a uniform boundary tension and mechanically coupled to an elastic substrate quantitatively captures the spatial distribution and magnitude of traction stresses. With a single choice of parameters, this model accurately predicts the cell's mechanical output over a wide range of cell geometries.
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Affiliation(s)
- Patrick W Oakes
- Institute for Biophysical Dynamics, James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois
| | - Shiladitya Banerjee
- Institute for Biophysical Dynamics, James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois; Department of Physics, Syracuse University, Syracuse, New York
| | - M Cristina Marchetti
- Department of Physics, Syracuse University, Syracuse, New York; Syracuse Biomaterials Institute, Syracuse University, Syracuse, New York
| | - Margaret L Gardel
- Institute for Biophysical Dynamics, James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois.
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29
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Stauch T, Dreuw A. A quantitative quantum-chemical analysis tool for the distribution of mechanical force in molecules. J Chem Phys 2015; 140:134107. [PMID: 24712780 DOI: 10.1063/1.4870334] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The promising field of mechanochemistry suffers from a general lack of understanding of the distribution and propagation of force in a stretched molecule, which limits its applicability up to the present day. In this article, we introduce the JEDI (Judgement of Energy DIstribution) analysis, which is the first quantum chemical method that provides a quantitative understanding of the distribution of mechanical stress energy among all degrees of freedom in a molecule. The method is carried out on the basis of static or dynamic calculations under the influence of an external force and makes use of a Hessian matrix in redundant internal coordinates (bond lengths, bond angles, and dihedral angles), so that all relevant degrees of freedom of a molecule are included and mechanochemical processes can be interpreted in a chemically intuitive way. The JEDI method is characterized by its modest computational effort, with the calculation of the Hessian being the rate-determining step, and delivers, except for the harmonic approximation, exact ab initio results. We apply the JEDI analysis to several example molecules in both static quantum chemical calculations and Born-Oppenheimer Molecular Dynamics simulations in which molecules are subject to an external force, thus studying not only the distribution and the propagation of strain in mechanically deformed systems, but also gaining valuable insights into the mechanochemically induced isomerization of trans-3,4-dimethylcyclobutene to trans,trans-2,4-hexadiene. The JEDI analysis can potentially be used in the discussion of sonochemical reactions, molecular motors, mechanophores, and photoswitches as well as in the development of molecular force probes.
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Affiliation(s)
- Tim Stauch
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany
| | - Andreas Dreuw
- Interdisciplinary Center for Scientific Computing, University of Heidelberg, Im Neuenheimer Feld 368, 69120 Heidelberg, Germany
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30
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Dynamics of cell shape and forces on micropatterned substrates predicted by a cellular Potts model. Biophys J 2015; 106:2340-52. [PMID: 24896113 DOI: 10.1016/j.bpj.2014.04.036] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Revised: 04/23/2014] [Accepted: 04/25/2014] [Indexed: 11/23/2022] Open
Abstract
Micropatterned substrates are often used to standardize cell experiments and to quantitatively study the relation between cell shape and function. Moreover, they are increasingly used in combination with traction force microscopy on soft elastic substrates. To predict the dynamics and steady states of cell shape and forces without any a priori knowledge of how the cell will spread on a given micropattern, here we extend earlier formulations of the two-dimensional cellular Potts model. The third dimension is treated as an area reservoir for spreading. To account for local contour reinforcement by peripheral bundles, we augment the cellular Potts model by elements of the tension-elasticity model. We first parameterize our model and show that it accounts for momentum conservation. We then demonstrate that it is in good agreement with experimental data for shape, spreading dynamics, and traction force patterns of cells on micropatterned substrates. We finally predict shapes and forces for micropatterns that have not yet been experimentally studied.
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31
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Dingal PCDP, Discher DE. Systems mechanobiology: tension-inhibited protein turnover is sufficient to physically control gene circuits. Biophys J 2014; 107:2734-43. [PMID: 25468352 DOI: 10.1016/j.bpj.2014.10.042] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 10/17/2014] [Accepted: 10/27/2014] [Indexed: 11/16/2022] Open
Abstract
Mechanotransduction pathways convert forces that stress and strain structures within cells into gene expression levels that impact development, homeostasis, and disease. The levels of some key structural proteins in the nucleus, cytoskeleton, or extracellular matrix have been recently reported to scale with tissue- and cell-level forces or mechanical properties such as stiffness, and so the mathematics of mechanotransduction becomes important to understand. Here, we show that if a given structural protein positively regulates its own gene expression, then stresses need only inhibit degradation of that protein to achieve stable, mechanosensitive gene expression. This basic use-it-or-lose-it module is illustrated by application to meshworks of nuclear lamin A, minifilaments of myosin II, and extracellular matrix collagen fibers—all of which possess filamentous coiled-coil/supercoiled structures. Past experiments not only suggest that tension suppresses protein degradation mediated and/or initiated by various enzymes but also that transcript levels vary with protein levels because key transcription factors are regulated by these structural proteins. Coupling between modules occurs within single cells and between cells in tissue, as illustrated during embryonic heart development where cardiac fibroblasts make collagen that cardiomyocytes contract. With few additional assumptions, the basic module has sufficient physics to control key structural genes in both development and disease.
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Affiliation(s)
- P C Dave P Dingal
- Molecular and Cell Biophysics Laboratory, Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Dennis E Discher
- Molecular and Cell Biophysics Laboratory, Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania; Graduate Groups in Physics and Cell & Molecular Biology, University of Pennsylvania, Philadelphia, Pennsylvania.
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32
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Pok S, Jacot JG. Work and tension: new evidence that adherent cells of the same area do the same work independent of stiffness and focal adhesions. Biophys J 2014; 107:798-9. [PMID: 25140413 DOI: 10.1016/j.bpj.2014.07.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/01/2014] [Indexed: 11/26/2022] Open
Affiliation(s)
- Seokwon Pok
- Department of Bioengineering, Rice University, Houston, Texas
| | - Jeffrey G Jacot
- Department of Bioengineering, Rice University, Houston, Texas; Division of Congenital Heart Surgery, Texas Children's Hospital, Houston, Texas.
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Theisen KE, Desai NJ, Volski AM, Dima RI. Mechanics of severing for large microtubule complexes revealed by coarse-grained simulations. J Chem Phys 2014; 139:121926. [PMID: 24089738 DOI: 10.1063/1.4819817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
We investigate the mechanical behavior of microtubule (MT) protofilaments under the action of bending forces, ramped up linearly in time, to provide insight into the severing of MTs by microtubule associated proteins (MAPs). We used the self-organized polymer model which employs a coarse-grained description of the protein chain and ran Brownian dynamics simulations accelerated on graphics processing units that allow us to follow the dynamics of a MT system on experimental timescales. Our study focused on the role played in the MT depolymerization dynamics by the inter-tubulin contacts a protofilament experiences when embedded in the MT lattice, and the number of binding sites of MAPs on MTs. We found that proteins inducing breaking of MTs must have at least three attachment points on any tubulin dimer from an isolated protofilament. In contrast, two points of contact would suffice when dimers are located in an intact MT lattice, in accord with experimental findings on MT severing proteins. Our results show that confinement of a protofilament in the MT lattice leads to a drastic reduction in the energy required for the removal of tubulin dimers, due to the drastic reduction in entropy. We further showed that there are differences in the energetic requirements based on the location of the dimer to be removed by severing. Comparing the energy of tubulin dimers removal revealed by our simulations with the amount of energy resulting from one ATP hydrolysis, which is the source of energy for all MAPs, we provided strong evidence for the experimental finding that severing proteins do not bind uniformly along the MT wall.
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Affiliation(s)
- Kelly E Theisen
- Department of Chemistry, University of Cincinnati, Cincinnati, Ohio 45221, USA
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34
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Nisenholz N, Botton M, Zemel A. Early-time dynamics of actomyosin polarization in cells of confined shape in elastic matrices. SOFT MATTER 2014; 10:2453-2462. [PMID: 24623163 DOI: 10.1039/c3sm52524d] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The cell shape and the rigidity of the extracellular matrix have been shown to play an important role in the regulation of cytoskeleton structure and force generation. Elastic stresses that develop by actomyosin contraction feedback on myosin activity and govern the anisotropic polarization of stress fibers in the cell. We theoretically study the consequences that the cell shape and matrix rigidity may have on the dynamics and steady state polarization of actomyosin forces in the cell. Actomyosin forces are assumed to polarize in accordance with the stresses that develop in the cytoskeleton. The theory examines this self-polarization process as a relaxation response determined by two distinct susceptibility factors and two characteristic times. These reveal two canonical polarization responses to local variations in the elastic stress: an isotropic response, in which actomyosin dipolar stress isotropically changes in magnitude, and an orientational response, in which actomyosin forces orient with no net change in magnitude. Actual polarization may show up as a superimposition of the two mechanisms yielding different phases in the polarization response as observed experimentally. The cell shape and elastic moduli of the surroundings are shown to govern both the dynamics of the process as well as the steady-state. We predict that in the steady-state, beyond a critical matrix rigidity, spherical cells exert maximal force, and below that rigidity, elongated or flattened cells exert more force. Similar behaviors are reflected in the rate of the polarization process. The theory is also applicable to study the elastic response of whole cell aggregates in a gel.
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Affiliation(s)
- Noam Nisenholz
- Institute of Dental Sciences and the Fritz Haber Center for Molecular Dynamics, The Hebrew University-Hadassah Medical Center, Jerusalem, 91120, Israel.
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35
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WU PEIJUNG, LIN CHOUCHINGK, JU MINGSHAUNG. ONE-DIMENSIONAL MODELING AND SIMULATIONS OF MIGRATION OF CULTURED FIBROBLASTS. J MECH MED BIOL 2014. [DOI: 10.1142/s0219519414500274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Cell migration is crucial for many physiological functions such as wound healing, immuno-response and carcinogenesis. In this study an one-dimensional model of migration of fibroblasts was developed by modeling and integrating five subcellular processes, namely, actin protrusion, focal adhesion formation, stress fiber formation, polarization and retraction. The direction of migration was determined by polarization, which was related to direction of the stiffness gradient of the substrate. By controlling intensity of ultraviolet exposure on type-I collagen, a substrate with a stiffness gradient could be fabricated. Kinematic analyses of positions of the cell front, the nucleus and the cell rear, were utilized as inputs to the model. Simulation results of five live NIH 3T3 fibroblasts showed that the model was capable of simulating fast moving, slow moving and back-and-forth moving of the cells on the substrate.
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Affiliation(s)
- PEI-JUNG WU
- Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan 701, Taiwan
| | - CHOU-CHING K. LIN
- Department of Neurology, National Cheng Kung University Hospital, College of Medicine, Tainan, Taiwan 701, Taiwan
- Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan 701, Taiwan
| | - MING-SHAUNG JU
- Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan 701, Taiwan
- Medical Device Innovation Center, National Cheng Kung University, Tainan, Taiwan 701, Taiwan
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36
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Pritchard RH, Huang YYS, Terentjev EM. Mechanics of biological networks: from the cell cytoskeleton to connective tissue. SOFT MATTER 2014; 10:1864-84. [PMID: 24652375 DOI: 10.1039/c3sm52769g] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
From the cell cytoskeleton to connective tissues, fibrous networks are ubiquitous in metazoan life as the key promoters of mechanical strength, support and integrity. In recent decades, the application of physics to biological systems has made substantial strides in elucidating the striking mechanical phenomena observed in such networks, explaining strain stiffening, power law rheology and cytoskeletal fluidisation - all key to the biological function of individual cells and tissues. In this review we focus on the current progress in the field, with a primer into the basic physics of individual filaments and the networks they form. This is followed by a discussion of biological networks in the context of a broad spread of recent in vitro and in vivo experiments.
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Affiliation(s)
- Robyn H Pritchard
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
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37
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Nava MM, Raimondi MT, Pietrabissa R. Bio-chemo-mechanical models for nuclear deformation in adherent eukaryotic cells. Biomech Model Mechanobiol 2014; 13:929-43. [DOI: 10.1007/s10237-014-0558-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 01/30/2014] [Indexed: 12/12/2022]
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Wang L, Chen T, Zhou X, Huang Q, Jin C. Atomic force microscopy observation of lipopolysaccharide-induced cardiomyocyte cytoskeleton reorganization. Micron 2013; 51:48-53. [PMID: 23906659 DOI: 10.1016/j.micron.2013.06.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Revised: 06/24/2013] [Accepted: 06/25/2013] [Indexed: 12/01/2022]
Abstract
We applied atomic force microscopy (AFM) to observe lipopolysaccharide (LPS)-induced intracellular cytoskeleton reorganization in primary cardiomyocytes from neonatal mouse. The nonionic detergent Triton X-100 was used to remove the membrane, soluble proteins, and organelles from the cell. The remaining cytoskeleton can then be directly visualized by AFM. Using three-dimensional technique of AFM, we were able to quantify the changes of cytoskeleton by the "density" and total "volume" of the cytoskeleton fibers. Compared to the control group, the density of cytoskeleton was remarkably decreased and the volume of cytoskeleton was significantly increased after LPS treatment, which suggests that LPS may induce the cytoskeleton reorganization and change the cardiomyocyte morphology.
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Affiliation(s)
- Liqun Wang
- Key Lab for Shock and Microcirculation Research, Department of Pathophysiology, Southern Medical University, Guangzhou 510515, PR China
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39
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Peschetola V, Laurent VM, Duperray A, Michel R, Ambrosi D, Preziosi L, Verdier C. Time-dependent traction force microscopy for cancer cells as a measure of invasiveness. Cytoskeleton (Hoboken) 2013; 70:201-14. [PMID: 23444002 DOI: 10.1002/cm.21100] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2012] [Revised: 01/08/2013] [Accepted: 02/05/2013] [Indexed: 12/18/2022]
Abstract
The migration of tumor cells of different degrees of invasivity is studied, on the basis of the traction forces exerted in time on soft substrates (Young modulus∼10 kPa). It is found that the outliers of the traction stresses can be an effective indicator to distinguish cancer cell lines of different invasiveness. Here, we test two different epithelial bladder cancer cell lines, one invasive (T24), and a less invasive one (RT112). Invasive cancer cells move in a nearly periodic motion, with peaks in velocity corresponding to higher traction forces exerted on the substrate, whereas less invasive cells develop traction stresses almost constant in time. The dynamics of focal adhesions (FAs) as well as cytoskeleton features reveals that different mechanisms are activated to migrate: T24 cells show an interconnected cytoskeleton linked to mature adhesion sites, leading to small traction stresses, whereas less invasive cells (RT112) show a less-structured cytoskeleton and unmature adhesions corresponding to higher traction stresses. Migration velocities are smaller in the case of less invasive cells. The mean squared displacement shows super-diffusive motion in both cases with higher exponent for the more invasive cancer cells. Further correlations between traction forces and the actin cytoskeleton reveal an unexpected pattern of a large actin rim at the RT112 cell edge where higher forces are colocalized, whereas a more usual cytoskeleton structure with stress fibers and FAs are found for T24 cancer cells. We conjecture that this kind of analysis can be useful to classify cancer cell invasiveness.
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40
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Mechanical models of the cellular cytoskeletal network for the analysis of intracellular mechanical properties and force distributions: A review. Med Eng Phys 2012; 34:1375-86. [DOI: 10.1016/j.medengphy.2012.08.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 07/31/2012] [Accepted: 08/09/2012] [Indexed: 11/24/2022]
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41
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Ladoux B, Nicolas A. Physically based principles of cell adhesion mechanosensitivity in tissues. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2012; 75:116601. [PMID: 23085962 DOI: 10.1088/0034-4885/75/11/116601] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The minimal structural unit that defines living organisms is a single cell. By proliferating and mechanically interacting with each other, cells can build complex organization such as tissues that ultimately organize into even more complex multicellular living organisms, such as mammals, composed of billions of single cells interacting with each other. As opposed to passive materials, living cells actively respond to the mechanical perturbations occurring in their environment. Tissue cell adhesion to its surrounding extracellular matrix or to neighbors is an example of a biological process that adapts to physical cues. The adhesion of tissue cells to their surrounding medium induces the generation of intracellular contraction forces whose amplitude adapts to the mechanical properties of the environment. In turn, solicitation of adhering cells with physical forces, such as blood flow shearing the layer of endothelial cells in the lumen of arteries, reinforces cell adhesion and impacts cell contractility. In biological terms, the sensing of physical signals is transduced into biochemical signaling events that guide cellular responses such as cell differentiation, cell growth and cell death. Regarding the biological and developmental consequences of cell adaptation to mechanical perturbations, understanding mechanotransduction in tissue cell adhesion appears as an important step in numerous fields of biology, such as cancer, regenerative medicine or tissue bioengineering for instance. Physicists were first tempted to view cell adhesion as the wetting transition of a soft bag having a complex, adhesive interaction with the surface. But surprising responses of tissue cell adhesion to mechanical cues challenged this view. This, however, did not exclude that cell adhesion could be understood in physical terms. It meant that new models and descriptions had to be created specifically for these biological issues, and could not straightforwardly be adapted from dead matter. In this review, we present physical concepts of tissue cell adhesion and the unexpected cellular responses to mechanical cues such as external forces and stiffness sensing. We show how biophysical approaches, both experimentally and theoretically, have contributed to our understanding of the regulation of cellular functions through physical force sensing mechanisms. Finally, we discuss the different physical models that could explain how tissue cell adhesion and force sensing can be coupled to internal mechanosensitive processes within the cell body.
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Affiliation(s)
- Benoit Ladoux
- Laboratoire Matière et Systèmes Complexes (MSC), CNRS UMR 7057 & Université Paris Diderot, Paris, France.
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42
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Milner JS, Grol MW, Beaucage KL, Dixon SJ, Holdsworth DW. Finite-element modeling of viscoelastic cells during high-frequency cyclic strain. J Funct Biomater 2012; 3:209-24. [PMID: 24956525 PMCID: PMC4031015 DOI: 10.3390/jfb3010209] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2012] [Revised: 03/06/2012] [Accepted: 03/13/2012] [Indexed: 12/20/2022] Open
Abstract
Mechanotransduction refers to the mechanisms by which cells sense and respond to local loads and forces. The process of mechanotransduction plays an important role both in maintaining tissue viability and in remodeling to repair damage; moreover, it may be involved in the initiation and progression of diseases such as osteoarthritis and osteoporosis. An understanding of the mechanisms by which cells respond to surrounding tissue matrices or artificial biomaterials is crucial in regenerative medicine and in influencing cellular differentiation. Recent studies have shown that some cells may be most sensitive to low-amplitude, high-frequency (i.e., 1-100 Hz) mechanical stimulation. Advances in finite-element modeling have made it possible to simulate high-frequency mechanical loading of cells. We have developed a viscoelastic finite-element model of an osteoblastic cell (including cytoskeletal actin stress fibers), attached to an elastomeric membrane undergoing cyclic isotropic radial strain with a peak value of 1,000 µstrain. The results indicate that cells experience significant stress and strain amplification when undergoing high-frequency strain, with peak values of cytoplasmic strain five times higher at 45 Hz than at 1 Hz, and peak Von Mises stress in the nucleus increased by a factor of two. Focal stress and strain amplification in cells undergoing high-frequency mechanical stimulation may play an important role in mechanotransduction.
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Affiliation(s)
- Jaques S Milner
- Imaging Research Laboratory, Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5K8, Canada.
| | - Matthew W Grol
- Department of Anatomy and Cell Biology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - Kim L Beaucage
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - S Jeffrey Dixon
- Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5C1, Canada.
| | - David W Holdsworth
- Imaging Research Laboratory, Robarts Research Institute, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON N6A 5K8, Canada.
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43
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Deguchi S, Matsui TS, Sato M. Simultaneous contraction and buckling of stress fibers in individual cells. J Cell Biochem 2012; 113:824-32. [DOI: 10.1002/jcb.23410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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44
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Möhl C, Kirchgessner N, Schäfer C, Hoffmann B, Merkel R. Quantitative mapping of averaged focal adhesion dynamics in migrating cells by shape normalization. J Cell Sci 2012; 125:155-65. [PMID: 22250204 DOI: 10.1242/jcs.090746] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The spatially ordered formation and disassembly of focal adhesions is a basic requirement for effective cell locomotion. Because focal adhesions couple the contractile actin-myosin network to the substrate, their distribution determines the pattern of traction forces propelling the cell in a certain direction. In the present study, we quantitatively analyzed the spatial patterning of cell-substrate adhesion in migrating cells by mapping averaged focal adhesion growth dynamics to a standardized cell coordinate system. These maps revealed distinct zones of focal adhesion assembly, disassembly and stability and were strongly interrelated with corresponding actin flow and traction force patterns. Moreover, the mapping technique enables precise detection of even minute responses of adhesion dynamics upon targeted signaling perturbations. For example, the partial inhibition of vinculin phosphorylation was followed by the reduced number of newly formed adhesions, whereas growth dynamics of existing adhesions remained unaffected.
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Affiliation(s)
- Christoph Möhl
- Institute of Complex Systems, ICS7: Biomechanics, Forschungszentrum Jülich GmbH, Jülich, Germany
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45
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Guthardt Torres P, Bischofs IB, Schwarz US. Contractile network models for adherent cells. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:011913. [PMID: 22400597 DOI: 10.1103/physreve.85.011913] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 12/07/2011] [Indexed: 05/31/2023]
Abstract
Cells sense the geometry and stiffness of their adhesive environment by active contractility. For strong adhesion to flat substrates, two-dimensional contractile network models can be used to understand how force is distributed throughout the cell. Here we compare the shape and force distribution for different variants of such network models. In contrast to Hookean networks, cable networks reflect the asymmetric response of biopolymers to tension versus compression. For passive networks, contractility is modeled by a reduced resting length of the mechanical links. In actively contracting networks, a constant force couple is introduced into each link in order to model contraction by molecular motors. If combined with fixed adhesion sites, all network models lead to invaginated cell shapes, but only actively contracting cable networks lead to the circular arc morphology typical for strongly adhering cells. In this case, shape and force distribution are determined by local rather than global determinants and thus are suited to endow the cell with a robust sense of its environment. We also discuss nonlinear and adaptive linker mechanics as well as the relation to tissue shape.
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Affiliation(s)
- P Guthardt Torres
- Heidelberg University, Institute for Theoretical Physics, Philosophenweg 19, D-69120 Heidelberg, Germany
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46
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Dado D, Sagi M, Levenberg S, Zemel A. Mechanical control of stem cell differentiation. Regen Med 2012; 7:101-16. [DOI: 10.2217/rme.11.99] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Numerous studies have focused on identifying the chemical and biological factors that govern the differentiation of stem cells; however, recent research has shown that mechanical cues may play an equally important role. Mechanical forces such as shear stresses and tensile loads, as well as the rigidity and topography of the extracellular matrix were shown to induce significant changes in the morphology and fate of stem cells. We survey experimental studies that focused on the response of stem cells to mechanical and geometrical properties of their environment and discuss the mechanical mechanisms that accompany their response including the remodeling of the cytoskeleton and determination of cell and nucleus size and shape.
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Affiliation(s)
- Dekel Dado
- Biomedical Engineering, Technion, Haifa, 32000, Israel
| | - Maayan Sagi
- Institute of Dental Sciences & the Fritz Haber Research Center, Hebrew-University, Hadassah Medical Center, Jerusalem, 91120, Israel
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47
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Frequency-Dependent Focal Adhesion Instability and Cell Reorientation Under Cyclic Substrate Stretching. Cell Mol Bioeng 2011. [DOI: 10.1007/s12195-011-0187-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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48
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Advances in Experiments and Modeling in Micro- and Nano-Biomechanics: A Mini Review. Cell Mol Bioeng 2011. [DOI: 10.1007/s12195-011-0183-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
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49
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Besser A, Colombelli J, Stelzer EHK, Schwarz US. Viscoelastic response of contractile filament bundles. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 83:051902. [PMID: 21728567 DOI: 10.1103/physreve.83.051902] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 02/18/2011] [Indexed: 05/31/2023]
Abstract
The actin cytoskeleton of adherent tissue cells often condenses into filament bundles contracted by myosin motors, so-called stress fibers, which play a crucial role in the mechanical interaction of cells with their environment. Stress fibers are usually attached to their environment at the endpoints, but possibly also along their whole length. We introduce a theoretical model for such contractile filament bundles which combines passive viscoelasticity with active contractility. The model equations are solved analytically for two different types of boundary conditions. A free boundary corresponds to stress fiber contraction dynamics after laser surgery and results in good agreement with experimental data. Imposing cyclic varying boundary forces allows us to calculate the complex modulus of a single stress fiber.
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Affiliation(s)
- Achim Besser
- University of Heidelberg, Bioquant, Im Neuenheimer Feld 267, Heidelberg
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50
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Modeling myosin-dependent rearrangement and force generation in an actomyosin network. J Theor Biol 2011; 281:65-73. [PMID: 21514305 DOI: 10.1016/j.jtbi.2011.04.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Revised: 03/21/2011] [Accepted: 04/07/2011] [Indexed: 11/21/2022]
Abstract
Actomyosin contractility is a major force-generating mechanism that drives rearrangement of actomyosin networks; it is fundamental to cellular functions such as cellular reshaping and movement. Thus, to clarify the mechanochemical foundation of the emergence of cellular functions, understanding the relationship between actomyosin contractility and rearrangement of actomyosin networks is crucial. For this purpose, in this study, we present a new particulate-based model for simulating the motions of actin, non-muscle myosin II, and α-actinin. To confirm the model's validity, we successfully simulated sliding and bending motions of actomyosin filaments, which are observed as fundamental behaviors in dynamic rearrangement of actomyosin networks in migrating keratocytes. Next, we simulated the dynamic rearrangement of actomyosin networks. Our simulation results indicate that an increase in the density fraction of myosin induces a higher-order structural transition of actomyosin filaments from networks to bundles, in addition to increasing the force generated by actomyosin filaments in the network. We compare our simulation results with experimental results and confirm that actomyosin bundles bridging focal adhesions and the characteristics of myosin-dependent rearrangement of actomyosin networks agree qualitatively with those observed experimentally.
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