1
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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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Amiri S, Muresan C, Shang X, Huet-Calderwood C, Schwartz MA, Calderwood DA, Murrell M. Intracellular tension sensor reveals mechanical anisotropy of the actin cytoskeleton. Nat Commun 2023; 14:8011. [PMID: 38049429 PMCID: PMC10695988 DOI: 10.1038/s41467-023-43612-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 11/15/2023] [Indexed: 12/06/2023] Open
Abstract
The filamentous actin (F-actin) cytoskeleton is a composite material consisting of cortical actin and bundled F-actin stress fibers, which together mediate the mechanical behaviors of the cell, from cell division to cell migration. However, as mechanical forces are typically measured upon transmission to the extracellular matrix, the internal distribution of forces within the cytoskeleton is unknown. Likewise, how distinct F-actin architectures contribute to the generation and transmission of mechanical forces is unclear. Therefore, we have developed a molecular tension sensor that embeds into the F-actin cytoskeleton. Using this sensor, we measure tension within stress fibers and cortical actin, as the cell is subject to uniaxial stretch. We find that the mechanical response, as measured by FRET, depends on the direction of applied stretch relative to the cell's axis of alignment. When the cell is aligned parallel to the direction of the stretch, stress fibers and cortical actin both accumulate tension. By contrast, when aligned perpendicular to the direction of stretch, stress fibers relax tension while the cortex accumulates tension, indicating mechanical anisotropy within the cytoskeleton. We further show that myosin inhibition regulates this anisotropy. Thus, the mechanical anisotropy of the cell and the coordination between distinct F-actin architectures vary and depend upon applied load.
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Affiliation(s)
- Sorosh Amiri
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA
- Department of Mechanical Engineering and Material Science, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
| | - Camelia Muresan
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
| | - Xingbo Shang
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
| | | | - Martin A Schwartz
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA
- Department of Cell Biology, 333 Cedar St, Yale University, New Haven, CT, 06510, USA
- Yale Cardiovascular Research Center, 300 George St, New Haven, CT, 06511, USA
| | - David A Calderwood
- Department of Pharmacology, 333 Cedar St, Yale University, New Haven, CT, 06510, USA
- Department of Cell Biology, 333 Cedar St, Yale University, New Haven, CT, 06510, USA
| | - Michael Murrell
- Systems Biology Institute, 850 West Campus Drive, Yale University, West Haven, CT, 06516, USA.
- Department of Biomedical Engineering, 17 Hillhouse Ave, Yale University, New Haven, CT, 06511, USA.
- Department of Physics, 217 Prospect Street, Yale University, New Haven, CT, 06511, USA.
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3
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Mahutga RR, Barocas VH, Alford PW. The non-affine fiber network solver: A multiscale fiber network material model for finite-element analysis. J Mech Behav Biomed Mater 2023; 144:105967. [PMID: 37329673 PMCID: PMC10330778 DOI: 10.1016/j.jmbbm.2023.105967] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2023] [Revised: 06/01/2023] [Accepted: 06/06/2023] [Indexed: 06/19/2023]
Abstract
Multiscale mechanical models in biomaterials research have largely relied on simplifying the microstructure in order to make large-scale simulations tractable. The microscale simplifications often rely on approximations of the constituent distributions and assumptions on the deformation of the constituents. Of particular interest in biomechanics are fiber embedded materials, where simplified fiber distributions and assumed affinity in the fiber deformation greatly influence the mechanical behavior. The consequences of these assumptions are problematic when dealing with microscale mechanical phenomena such as cellular mechanotransduction in growth and remodeling, and fiber-level failure events during tissue failure. In this work, we propose a technique for coupling non-affine network models to finite element solvers, allowing for simulation of discrete microstructural phenomena within macroscopically complex geometries. The developed plugin is readily available as an open-source library for use with the bio-focused finite element software FEBio, and the description of the implementation allows for the adaptation to other finite element solvers.
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Affiliation(s)
- Ryan R Mahutga
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA.
| | - Victor H Barocas
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
| | - Patrick W Alford
- Department of Biomedical Engineering, University of Minnesota - Twin Cities, Minneapolis, MN, USA
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4
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Actin crosslinking by α-actinin averts viscous dissipation of myosin force transmission in stress fibers. iScience 2023; 26:106090. [PMID: 36852278 PMCID: PMC9958379 DOI: 10.1016/j.isci.2023.106090] [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: 06/06/2022] [Revised: 01/13/2023] [Accepted: 01/25/2023] [Indexed: 02/04/2023] Open
Abstract
Contractile force generated in actomyosin stress fibers (SFs) is transmitted along SFs to the extracellular matrix (ECM), which contributes to cell migration and sensing of ECM rigidity. In this study, we show that efficient force transmission along SFs relies on actin crosslinking by α-actinin. Upon reduction of α-actinin-mediated crosslinks, the myosin II activity induced flows of actin filaments and myosin II along SFs, leading to a decrease in traction force exertion to ECM. The fluidized SFs maintained their cable integrity probably through enhanced actin polymerization throughout SFs. A computational modeling analysis suggested that lowering the density of actin crosslinks caused viscous slippage of actin filaments in SFs and, thereby, dissipated myosin-generated force transmitting along SFs. As a cellular scale outcome, α-actinin depletion attenuated the ECM-rigidity-dependent difference in cell migration speed, which suggested that α-actinin-modulated SF mechanics is involved in the cellular response to ECM rigidity.
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5
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Hohmann U, von Widdern JC, Ghadban C, Giudice MCL, Lemahieu G, Cavalcanti-Adam EA, Dehghani F, Hohmann T. Jamming Transitions in Astrocytes and Glioblastoma Are Induced by Cell Density and Tension. Cells 2022; 12:cells12010029. [PMID: 36611824 PMCID: PMC9818602 DOI: 10.3390/cells12010029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/07/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022] Open
Abstract
Collective behavior of cells emerges from coordination of cell-cell-interactions and is important to wound healing, embryonic and tumor development. Depending on cell density and cell-cell interactions, a transition from a migratory, fluid-like unjammed state to a more static and solid-like jammed state or vice versa can occur. Here, we analyze collective migration dynamics of astrocytes and glioblastoma cells using live cell imaging. Furthermore, atomic force microscopy, traction force microscopy and spheroid generation assays were used to study cell adhesion, traction and mechanics. Perturbations of traction and adhesion were induced via ROCK or myosin II inhibition. Whereas astrocytes resided within a non-migratory, jammed state, glioblastoma were migratory and unjammed. Furthermore, we demonstrated that a switch from an unjammed to a jammed state was induced upon alteration of the equilibrium between cell-cell-adhesion and tension from adhesion to tension dominated, via inhibition of ROCK or myosin II. Such behavior has implications for understanding the infiltration of the brain by glioblastoma cells and may help to identify new strategies to develop anti-migratory drugs and strategies for glioblastoma-treatment.
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Affiliation(s)
- Urszula Hohmann
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, 06108 Halle (Saale), Germany
| | - Julian Cardinal von Widdern
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, 06108 Halle (Saale), Germany
| | - Chalid Ghadban
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, 06108 Halle (Saale), Germany
| | - Maria Cristina Lo Giudice
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | - Grégoire Lemahieu
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, 69120 Heidelberg, Germany
| | | | - Faramarz Dehghani
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, 06108 Halle (Saale), Germany
| | - Tim Hohmann
- Department of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, 06108 Halle (Saale), Germany
- Correspondence:
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6
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Liu G, Li J, Wu C. Reciprocal regulation of actin filaments and cellular metabolism. Eur J Cell Biol 2022; 101:151281. [PMID: 36343493 DOI: 10.1016/j.ejcb.2022.151281] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Revised: 09/23/2022] [Accepted: 10/25/2022] [Indexed: 12/14/2022] Open
Abstract
For cells to adhere, migrate and proliferate, remodeling of the actin cytoskeleton is required. This process consumes a large amount of ATP while having an intimate connection with cellular metabolism. Signaling pathways that regulate energy homeostasis can also affect actin dynamics, whereas a variety of actin binding proteins directly or indirectly interact with the anabolic and catabolic regulators in cells. Here, we discuss the inter-regulation between actin filaments and cellular metabolism, reviewing recent discoveries on key metabolic enzymes that respond to actin remodeling as well as historical findings on metabolic stress-induced cytoskeletal reorganization. We also address emerging techniques that would benefit the study of cytoskeletal dynamics and cellular metabolism in high spatial-temporal resolution.
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Affiliation(s)
- Geyao Liu
- Institute of Systems Biomedicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Jiayi Li
- Institute of Systems Biomedicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Congying Wu
- Institute of Systems Biomedicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China; International Cancer Institute, Peking University, Beijing 100191, China.
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7
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Nanoscale geometry determines mechanical biocompatibility of vertically aligned nanofibers. Acta Biomater 2022; 146:235-247. [PMID: 35487425 DOI: 10.1016/j.actbio.2022.04.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 04/11/2022] [Accepted: 04/20/2022] [Indexed: 11/24/2022]
Abstract
Vertically aligned carbon nanofibers (VACNFs) are promising material candidates for neural biosensors due to their ability to detect neurotransmitters in physiological concentrations. However, the expected high rigidity of CNFs could induce mechanical mismatch with the brain tissue, eliciting formation of a glial scar around the electrode and thus loss of functionality. We have evaluated mechanical biocompatibility of VACNFs by growing nickel-catalyzed carbon nanofibers of different lengths and inter-fiber distances. Long nanofibers with large inter-fiber distance prevented maturation of focal adhesions, thus constraining cells from obtaining a highly spread morphology that is observed when astrocytes are being contacted with stiff materials commonly used in neural implants. A silicon nanopillar array with 500 nm inter-pillar distance was used to reveal that this inhibition of focal adhesion maturation occurs due to the surface nanoscale geometry, more precisely the inter-fiber distance. Live cell atomic force microscopy was used to confirm astrocytes being significantly softer on the long Ni-CNFs compared to other surfaces, including a soft gelatin hydrogel. We also observed hippocampal neurons to mature and form synaptic contacts when being cultured on both long and short carbon nanofibers, without having to use any adhesive proteins or a glial monoculture, indicating high cytocompatibility of the material also with neuronal population. In contrast, neurons cultured on a planar tetrahedral amorphous carbon sample showed immature neurites and indications of early-stage apoptosis. Our results demonstrate that mechanical biocompatibility of biomaterials is greatly affected by their nanoscale surface geometry, which provides means for controlling how the materials and their mechanical properties are perceived by the cells. STATEMENT OF SIGNIFICANCE: Our research article shows, how nanoscale surface geometry determines mechanical biocompatibility of apparently stiff materials. Specifically, astrocytes were prevented from obtaining highly spread morphology when their adhesion site maturation was inhibited, showing similar morphology on nominally stiff vertically aligned carbon fiber (VACNF) substrates as when being cultured on ultrasoft surfaces. Furthermore, hippocampal neurons matured well and formed synapses on these carbon nanofibers, indicating high biocompatibility of the materials. Interestingly, the same VACNF materials that were used in this study have earlier also been proven to be capable for electrophysiological recordings and sensing neurotransmitters at physiological concentrations with ultra-high sensitivity and selectivity, thus providing a platform for future neural probes or smart culturing surfaces with superior sensing performance and biocompatibility.
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8
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Bhargav AG, Domino JS, Chamoun R, Thomas SM. Mechanical Properties in the Glioma Microenvironment: Emerging Insights and Theranostic Opportunities. Front Oncol 2022; 11:805628. [PMID: 35127517 PMCID: PMC8813748 DOI: 10.3389/fonc.2021.805628] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 12/29/2021] [Indexed: 12/30/2022] Open
Abstract
Gliomas represent the most common malignant primary brain tumors, and a high-grade subset of these tumors including glioblastoma are particularly refractory to current standard-of-care therapies including maximal surgical resection and chemoradiation. The prognosis of patients with these tumors continues to be poor with existing treatments and understanding treatment failure is required. The dynamic interplay between the tumor and its microenvironment has been increasingly recognized as a key mechanism by which cellular adaptation, tumor heterogeneity, and treatment resistance develops. Beyond ongoing lines of investigation into the peritumoral cellular milieu and microenvironmental architecture, recent studies have identified the growing role of mechanical properties of the microenvironment. Elucidating the impact of these biophysical factors on disease heterogeneity is crucial for designing durable therapies and may offer novel approaches for intervention and disease monitoring. Specifically, pharmacologic targeting of mechanical signal transduction substrates such as specific ion channels that have been implicated in glioma progression or the development of agents that alter the mechanical properties of the microenvironment to halt disease progression have the potential to be promising treatment strategies based on early studies. Similarly, the development of technology to measure mechanical properties of the microenvironment in vitro and in vivo and simulate these properties in bioengineered models may facilitate the use of mechanical properties as diagnostic or prognostic biomarkers that can guide treatment. Here, we review current perspectives on the influence of mechanical properties in glioma with a focus on biophysical features of tumor-adjacent tissue, the role of fluid mechanics, and mechanisms of mechanical signal transduction. We highlight the implications of recent discoveries for novel diagnostics, therapeutic targets, and accurate preclinical modeling of glioma.
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Affiliation(s)
- Adip G. Bhargav
- Department of Neurological Surgery, University of Kansas Medical Center, Kansas City, KS, United States
| | - Joseph S. Domino
- Department of Neurological Surgery, University of Kansas Medical Center, Kansas City, KS, United States
| | - Roukoz Chamoun
- Department of Neurological Surgery, University of Kansas Medical Center, Kansas City, KS, United States
| | - Sufi M. Thomas
- Department of Otolaryngology, University of Kansas Medical Center, Kansas City, KS, United States
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9
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Rimoli CV, Valades-Cruz CA, Curcio V, Mavrakis M, Brasselet S. 4polar-STORM polarized super-resolution imaging of actin filament organization in cells. Nat Commun 2022; 13:301. [PMID: 35027553 PMCID: PMC8758668 DOI: 10.1038/s41467-022-27966-w] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 12/20/2021] [Indexed: 11/18/2022] Open
Abstract
Single-molecule localization microscopy provides insights into the nanometer-scale spatial organization of proteins in cells, however it does not provide information on their conformation and orientation, which are key functional signatures. Detecting single molecules' orientation in addition to their localization in cells is still a challenging task, in particular in dense cell samples. Here, we present a polarization-splitting scheme which combines Stochastic Optical Reconstruction Microscopy (STORM) with single molecule 2D orientation and wobbling measurements, without requiring a strong deformation of the imaged point spread function. This method called 4polar-STORM allows, thanks to a control of its detection numerical aperture, to determine both single molecules' localization and orientation in 2D and to infer their 3D orientation. 4polar-STORM is compatible with relatively high densities of diffraction-limited spots in an image, and is thus ideally placed for the investigation of dense protein assemblies in cells. We demonstrate the potential of this method in dense actin filament organizations driving cell adhesion and motility.
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Affiliation(s)
- Caio Vaz Rimoli
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France
| | - Cesar Augusto Valades-Cruz
- Institut Curie, PSL Research University, UMR144 CNRS, Space-Time imaging of organelles and Endomembranes Dynamics Team, F-75005, Paris, France
- Inria Centre Rennes-Bretagne Atlantique, SERPICO Project Team, F-35042, Rennes, France
| | - Valentina Curcio
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France
| | - Manos Mavrakis
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France.
| | - Sophie Brasselet
- Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, F-13013, Marseille, France.
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10
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Sorensen DW, Injeti ER, Mejia-Aguilar L, Williams JM, Pearce WJ. Postnatal development alters functional compartmentalization of myosin light chain kinase in ovine carotid arteries. Am J Physiol Regul Integr Comp Physiol 2021; 321:R441-R453. [PMID: 34318702 PMCID: PMC8530762 DOI: 10.1152/ajpregu.00293.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The rate-limiting enzyme for vascular contraction, myosin light chain kinase (MLCK), phosphorylates regulatory myosin light chain (MLC20) at rates that appear faster despite lower MLCK abundance in fetal compared with adult arteries. This study explores the hypothesis that greater apparent tissue activity of MLCK in fetal arteries is due to age-dependent differences in intracellular distribution of MLCK in relation to MLC20. Under optimal conditions, common carotid artery homogenates from nonpregnant adult female sheep and near-term fetuses exhibited similar values of Vmax and Km for MLCK. A custom-designed, computer-controlled apparatus enabled electrical stimulation and high-speed freezing of arterial segments at exactly 0, 1, 2, and 3 s, calculation of in situ rates of MLC20 phosphorylation, and measurement of time-dependent colocalization between MLCK and MLC20. The in situ rate of MLC20 phosphorylation divided by total MLCK abundance averaged to values 147% greater in fetal (1.06 ± 0.28) than adult (0.43 ± 0.08) arteries, which corresponded, respectively, to 43 ± 10% and 31 ± 3% of the Vmax values measured in homogenates. Confocal colocalization analysis revealed in fetal and adult arteries that 33 ± 6% and 20 ± 5% of total MLCK colocalized with pMLC20, and that MLCK activation was greater in periluminal than periadventitial regions over the time course of electrical stimulation in both age groups. Together, these results demonstrate that the catalytic activity of MLCK is similar in fetal and adult arteries, but that the fraction of total MLCK in the functional compartment involved in contraction is significantly greater in fetal than adult arteries.
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Affiliation(s)
- Dane W Sorensen
- Division of Physiology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - Elisha R Injeti
- Department of Pharmaceutical Sciences, Cedarville University School of Pharmacy, Cedarville, Ohio
| | - Luisa Mejia-Aguilar
- Division of Physiology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - James M Williams
- Division of Physiology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
| | - William J Pearce
- Division of Physiology, Center for Perinatal Biology, Loma Linda University School of Medicine, Loma Linda, California
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11
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Müller D, Klamt T, Gentemann L, Heisterkamp A, Kalies SMK. Evaluation of laser induced sarcomere micro-damage: Role of damage extent and location in cardiomyocytes. PLoS One 2021; 16:e0252346. [PMID: 34086732 PMCID: PMC8177425 DOI: 10.1371/journal.pone.0252346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 05/12/2021] [Indexed: 11/18/2022] Open
Abstract
Whereas it is evident that a well aligned and regular sarcomeric structure in cardiomyocytes is vital for heart function, considerably less is known about the contribution of individual elements to the mechanics of the entire cell. For instance, it is unclear whether altered Z-disc elements are the reason or the outcome of related cardiomyopathies. Therefore, it is crucial to gain more insight into this cellular organization. This study utilizes femtosecond laser-based nanosurgery to better understand sarcomeres and their repair upon damage. We investigated the influence of the extent and the location of the Z-disc damage. A single, three, five or ten Z-disc ablations were performed in neonatal rat cardiomyocytes. We employed image-based analysis using a self-written software together with different already published algorithms. We observed that cardiomyocyte survival associated with the damage extent, but not with the cell area or the total number of Z-discs per cell. The cell survival is independent of the damage position and can be compensated. However, the sarcomere alignment/orientation is changing over time after ablation. The contraction time is also independent of the extent of damage for the tested parameters. Additionally, we observed shortening rates between 6–7% of the initial sarcomere length in laser treated cardiomyocytes. This rate is an important indicator for force generation in myocytes. In conclusion, femtosecond laser-based nanosurgery together with image-based sarcomere tracking is a powerful tool to better understand the Z-disc complex and its force propagation function and role in cellular mechanisms.
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Affiliation(s)
- Dominik Müller
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany
- REBIRTH Research Center for Translational Regenerative Medicine, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
- * E-mail:
| | - Thorben Klamt
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Lara Gentemann
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Alexander Heisterkamp
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany
- REBIRTH Research Center for Translational Regenerative Medicine, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Stefan Michael Klaus Kalies
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany
- REBIRTH Research Center for Translational Regenerative Medicine, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
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12
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Articular Chondrocyte Phenotype Regulation through the Cytoskeleton and the Signaling Processes That Originate from or Converge on the Cytoskeleton: Towards a Novel Understanding of the Intersection between Actin Dynamics and Chondrogenic Function. Int J Mol Sci 2021; 22:ijms22063279. [PMID: 33807043 PMCID: PMC8004672 DOI: 10.3390/ijms22063279] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 02/08/2023] Open
Abstract
Numerous studies have assembled a complex picture, in which extracellular stimuli and intracellular signaling pathways modulate the chondrocyte phenotype. Because many diseases are mechanobiology-related, this review asked to what extent phenotype regulators control chondrocyte function through the cytoskeleton and cytoskeleton-regulating signaling processes. Such information would generate leverage for advanced articular cartilage repair. Serial passaging, pro-inflammatory cytokine signaling (TNF-α, IL-1α, IL-1β, IL-6, and IL-8), growth factors (TGF-α), and osteoarthritis not only induce dedifferentiation but also converge on RhoA/ROCK/Rac1/mDia1/mDia2/Cdc42 to promote actin polymerization/crosslinking for stress fiber (SF) formation. SF formation takes center stage in phenotype control, as both SF formation and SOX9 phosphorylation for COL2 expression are ROCK activity-dependent. Explaining how it is molecularly possible that dedifferentiation induces low COL2 expression but high SF formation, this review theorized that, in chondrocyte SOX9, phosphorylation by ROCK might effectively be sidelined in favor of other SF-promoting ROCK substrates, based on a differential ROCK affinity. In turn, actin depolymerization for redifferentiation would “free-up” ROCK to increase COL2 expression. Moreover, the actin cytoskeleton regulates COL1 expression, modulates COL2/aggrecan fragment generation, and mediates a fibrogenic/catabolic expression profile, highlighting that actin dynamics-regulating processes decisively control the chondrocyte phenotype. This suggests modulating the balance between actin polymerization/depolymerization for therapeutically controlling the chondrocyte phenotype.
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13
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Vignaud T, Copos C, Leterrier C, Toro-Nahuelpan M, Tseng Q, Mahamid J, Blanchoin L, Mogilner A, Théry M, Kurzawa L. Stress fibres are embedded in a contractile cortical network. NATURE MATERIALS 2021; 20:410-420. [PMID: 33077951 PMCID: PMC7610471 DOI: 10.1038/s41563-020-00825-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 09/14/2020] [Indexed: 05/06/2023]
Abstract
Contractile actomyosin networks are responsible for the production of intracellular forces. There is increasing evidence that bundles of actin filaments form interconnected and interconvertible structures with the rest of the network. In this study, we explored the mechanical impact of these interconnections on the production and distribution of traction forces throughout the cell. By using a combination of hydrogel micropatterning, traction force microscopy and laser photoablation, we measured the relaxation of traction forces in response to local photoablations. Our experimental results and modelling of the mechanical response of the network revealed that bundles were fully embedded along their entire length in a continuous and contractile network of cortical filaments. Moreover, the propagation of the contraction of these bundles throughout the entire cell was dependent on this embedding. In addition, these bundles appeared to originate from the alignment and coalescence of thin and unattached cortical actin filaments from the surrounding mesh.
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Affiliation(s)
- Timothée Vignaud
- CytoMorpho Lab, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire et Végétale, Grenoble-Alpes University/CEA/CNRS/INRA, Grenoble, France
- CytoMorpho Lab, Hôpital Saint Louis, Institut Universitaire d'Hématologie, Université Paris Diderot/CEA/INSERM, Paris, France
- Clinique de Chirurgie Digestive et Endocrinienne, Hôtel Dieu, Nantes, France
| | - Calina Copos
- Courant Institute and Department of Biology, New York University, New York, NY, USA
| | - Christophe Leterrier
- NeuroCyto, Institute of NeuroPhysiopathology (INP), CNRS, Aix Marseille Université, Marseille, France
| | - Mauricio Toro-Nahuelpan
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Qingzong Tseng
- CytoMorpho Lab, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire et Végétale, Grenoble-Alpes University/CEA/CNRS/INRA, Grenoble, France
- CytoMorpho Lab, Hôpital Saint Louis, Institut Universitaire d'Hématologie, Université Paris Diderot/CEA/INSERM, Paris, France
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Laurent Blanchoin
- CytoMorpho Lab, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire et Végétale, Grenoble-Alpes University/CEA/CNRS/INRA, Grenoble, France
- CytoMorpho Lab, Hôpital Saint Louis, Institut Universitaire d'Hématologie, Université Paris Diderot/CEA/INSERM, Paris, France
| | - Alex Mogilner
- Courant Institute and Department of Biology, New York University, New York, NY, USA.
| | - Manuel Théry
- CytoMorpho Lab, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire et Végétale, Grenoble-Alpes University/CEA/CNRS/INRA, Grenoble, France.
- CytoMorpho Lab, Hôpital Saint Louis, Institut Universitaire d'Hématologie, Université Paris Diderot/CEA/INSERM, Paris, France.
| | - Laetitia Kurzawa
- CytoMorpho Lab, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire et Végétale, Grenoble-Alpes University/CEA/CNRS/INRA, Grenoble, France.
- CytoMorpho Lab, Hôpital Saint Louis, Institut Universitaire d'Hématologie, Université Paris Diderot/CEA/INSERM, Paris, France.
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14
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Abstract
Cancer cells accumulate iron to supplement their aberrant growth and metabolism. Depleting cells of iron by iron chelators has been shown to be selectively cytotoxic to cancer cells in vitro and in vivo. Iron chelators are effective at combating a range of cancers including those which are difficult to treat such as androgen insensitive prostate cancer and cancer stem cells. This review will evaluate the impact of iron chelation on cancer cell survival and the underlying mechanisms of action. A plethora of studies have shown iron chelators can reverse some of the major hallmarks and enabling characteristics of cancer. Iron chelators inhibit signalling pathways that drive proliferation, migration and metastasis as well as return tumour suppressive signalling. In addition to this, iron chelators stimulate apoptotic and ER stress signalling pathways inducing cell death even in cells lacking a functional p53 gene. Iron chelators can sensitise cancer cells to PARP inhibitors through mimicking BRCAness; a feature of cancers trademark genomic instability. Iron chelators target cancer cell metabolism, attenuating oxidative phosphorylation and glycolysis. Moreover, iron chelators may reverse the major characteristics of oncogenic transformation. Iron chelation therefore represent a promising selective mode of cancer therapy.
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15
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Tamashunas AC, Katiyar A, Zhang Q, Purkayastha P, Singh PK, Chukkapalli SS, Lele TP. Osteoprotegerin is sensitive to actomyosin tension in human periodontal ligament fibroblasts. J Cell Physiol 2021; 236:5715-5724. [PMID: 33400284 DOI: 10.1002/jcp.30256] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 11/28/2020] [Accepted: 12/22/2020] [Indexed: 12/11/2022]
Abstract
Periodontal ligament fibroblasts (PdLFs) are an elongated cell type in the periodontium with matrix and bone regulatory functions which become abnormal in periodontal disease (PD). Here we found that the normally elongated and oriented PdLF nucleus becomes rounded and loses orientation in a mouse model of PD. Using in vitro micropatterning of cultured primary PdLF cell shape, we show that PdLF elongation correlates with nuclear elongation and the presence of thicker, contractile F-actin fibers. The rounded nuclei in mouse PD models in vivo are, therefore, indicative of reduced actomyosin tension. Inhibiting actomyosin contractility by inhibiting myosin light chain kinase, Rho kinase or myosin ATPase activity, in cultured PdLFs each consistently reduced messenger RNA levels of bone regulatory protein osteoprotegerin (OPG). Infection of cultured PdLFs with two different types of periodontal bacteria (Porphyromonas gingivalis and Fusobacterium nucleatum) failed to recapitulate the observed nuclear rounding in vivo, upregulated nonmuscle myosin II phosphorylation and downregulated OPG. Collectively, our results add support to the hypothesis that PdLF contractility becomes decreased and contributes to disease progression in PD.
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Affiliation(s)
- Andrew C Tamashunas
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, USA
| | - Aditya Katiyar
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA
| | - Qiao Zhang
- Department of Chemical Engineering, University of Florida, Gainesville, Florida, USA
| | - Purboja Purkayastha
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA
| | - Pankaj K Singh
- GCC Center for Advanced Microscopy and Image Informatics, Houston, Texas, USA.,Center for Translational Cancer Research, Texas A&M University, Houston, Texas, USA
| | - Sasanka S Chukkapalli
- Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, Florida, USA.,Center for Molecular Microbiology, University of Florida, Gainesville, Florida, USA
| | - Tanmay P Lele
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, USA.,Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, USA.,Department of Translational Medical Sciences, Texas A&M University, College Station, Texas, USA
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16
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Horváth ÁI, Gyimesi M, Várkuti BH, Képiró M, Szegvári G, Lőrincz I, Hegyi G, Kovács M, Málnási-Csizmadia A. Effect of allosteric inhibition of non-muscle myosin 2 on its intracellular diffusion. Sci Rep 2020; 10:13341. [PMID: 32769996 PMCID: PMC7415145 DOI: 10.1038/s41598-020-69853-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Accepted: 07/03/2020] [Indexed: 12/12/2022] Open
Abstract
Subcellular dynamics of non-muscle myosin 2 (NM2) is crucial for a broad-array of cellular functions. To unveil mechanisms of NM2 pharmacological control, we determined how the dynamics of NM2 diffusion is affected by NM2′s allosteric inhibitors, i.e. blebbistatin derivatives, as compared to Y-27632 inhibiting ROCK, NM2′s upstream regulator. We found that NM2 diffusion is markedly faster in central fibers than in peripheral stress fibers. Y-27632 accelerated NM2 diffusion in both peripheral and central fibers, whereas in peripheral fibers blebbistatin derivatives slightly accelerated NM2 diffusion at low, but markedly slowed it at high inhibitor concentrations. In contrast, rapid NM2 diffusion in central fibers was unaffected by direct NM2 inhibition. Using our optopharmacological tool, Molecular Tattoo, sub-effective concentrations of a photo-crosslinkable blebbistatin derivative were increased to effective levels in a small, irradiated area of peripheral fibers. These findings suggest that direct allosteric inhibition affects the diffusion profile of NM2 in a markedly different manner compared to the disruption of the upstream control of NM2. The pharmacological action of myosin inhibitors is channeled through autonomous molecular processes and might be affected by the load acting on the NM2 proteins.
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Affiliation(s)
- Ádám I Horváth
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Máté Gyimesi
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Boglárka H Várkuti
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Miklós Képiró
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Gábor Szegvári
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - István Lőrincz
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - György Hegyi
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary
| | - Mihály Kovács
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary.
| | - András Málnási-Csizmadia
- MTA-ELTE Motor Pharmacology Research Group, Department of Biochemistry, Eötvös Loránd University, Pázmány Péter sétány 1/c, 1117, Budapest, Hungary.
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17
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Quantitative Phase Imaging of Spreading Fibroblasts Identifies the Role of Focal Adhesion Kinase in the Stabilization of the Cell Rear. Biomolecules 2020; 10:biom10081089. [PMID: 32707896 PMCID: PMC7463699 DOI: 10.3390/biom10081089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 07/14/2020] [Accepted: 07/20/2020] [Indexed: 12/11/2022] Open
Abstract
Cells attaching to the extracellular matrix spontaneously acquire front-rear polarity. This self-organization process comprises spatial activation of polarity signaling networks and the establishment of a protruding cell front and a non-protruding cell rear. Cell polarization also involves the reorganization of cell mass, notably the nucleus that is positioned at the cell rear. It remains unclear, however, how these processes are regulated. Here, using coherence-controlled holographic microscopy (CCHM) for non-invasive live-cell quantitative phase imaging (QPI), we examined the role of the focal adhesion kinase (FAK) and its interacting partner Rack1 in dry mass distribution in spreading Rat2 fibroblasts. We found that FAK-depleted cells adopt an elongated, bipolar phenotype with a high central body mass that gradually decreases toward the ends of the elongated processes. Further characterization of spreading cells showed that FAK-depleted cells are incapable of forming a stable rear; rather, they form two distally positioned protruding regions. Continuous protrusions at opposite sides results in an elongated cell shape. In contrast, Rack1-depleted cells are round and large with the cell mass sharply dropping from the nuclear area towards the basal side. We propose that FAK and Rack1 act differently yet coordinately to establish front-rear polarity in spreading cells.
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18
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Lee S, Kumar S. Cofilin is required for polarization of tension in stress fiber networks during migration. J Cell Sci 2020; 133:jcs243873. [PMID: 32501289 PMCID: PMC7358140 DOI: 10.1242/jcs.243873] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/11/2020] [Indexed: 01/04/2023] Open
Abstract
Cell migration is associated with the establishment of defined leading and trailing edges, which in turn requires polarization of contractile forces. While the actomyosin stress fiber (SF) network plays a critical role in enforcing this polarity, precisely how this asymmetry is established remains unclear. Here, we provide evidence for a model in which the actin-severing protein cofilin (specifically cofilin-1) participates in symmetry breakage by removing low-tension actomyosin filaments during transverse arc assembly. Cofilin knockdown (KD) produces a non-polarized SF architecture that cannot be rescued with chemokines or asymmetric matrix patterns. Whereas cofilin KD increases whole-cell prestress, it decreases prestress within single SFs, implying an accumulation of low-tension SFs. This notion is supported by time-lapse imaging, which reveals weakly contractile and incompletely fused transverse arcs. Confocal and super-resolution imaging further associate this failed fusion with the presence of crosslinker-rich, tropomyosin-devoid nodes at the junctions of multiple transverse arc fragments and dorsal SFs. These results support a model in which cofilin facilitates the formation of high-tension transverse arcs, thereby promoting mechanical asymmetry.
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Affiliation(s)
- Stacey Lee
- UC Berkeley-UCSF Graduate Program in Bioengineering, USA
- UC Berkeley Department of Bioengineering, UC Berkeley, CA, USA
| | - Sanjay Kumar
- UC Berkeley-UCSF Graduate Program in Bioengineering, USA
- UC Berkeley Department of Bioengineering, UC Berkeley, CA, USA
- UC Berkeley Department of Chemical and Biomolecular Engineering, 274A Stanley Hall #1762, UC Berkeley, Berkeley, CA 94720-1762, UC Berkeley, CA, USA
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19
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Intracellular nonequilibrium fluctuating stresses indicate how nonlinear cellular mechanical properties adapt to microenvironmental rigidity. Sci Rep 2020; 10:5902. [PMID: 32246074 PMCID: PMC7125211 DOI: 10.1038/s41598-020-62567-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 03/09/2020] [Indexed: 11/08/2022] Open
Abstract
Living cells are known to be in thermodynamically nonequilibrium, which is largely brought about by intracellular molecular motors. The motors consume chemical energies to generate stresses and reorganize the cytoskeleton for the cell to move and divide. However, since there has been a lack of direct measurements characterizing intracellular stresses, questions remained unanswered on the intricacies of how cells use such stresses to regulate their internal mechanical integrity in different microenvironments. This report describes a new experimental approach by which we reveal an environmental rigidity-dependent intracellular stiffness that increases with intracellular stress - a revelation obtained, surprisingly, from a correlation between the fluctuations in cellular stiffness and that of intracellular stresses. More surprisingly, by varying two distinct parameters, environmental rigidity and motor protein activities, we observe that the stiffness-stress relationship follows the same curve. This finding provides some insight into the intricacies by suggesting that cells can regulate their responses to their mechanical microenvironment by adjusting their intracellular stress.
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20
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Ellefsen KL, Holt JR, Chang AC, Nourse JL, Arulmoli J, Mekhdjian AH, Abuwarda H, Tombola F, Flanagan LA, Dunn AR, Parker I, Pathak MM. Myosin-II mediated traction forces evoke localized Piezo1-dependent Ca 2+ flickers. Commun Biol 2019; 2:298. [PMID: 31396578 PMCID: PMC6685976 DOI: 10.1038/s42003-019-0514-3] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 06/18/2019] [Indexed: 02/05/2023] Open
Abstract
Piezo channels transduce mechanical stimuli into electrical and chemical signals to powerfully influence development, tissue homeostasis, and regeneration. Studies on Piezo1 have largely focused on transduction of "outside-in" mechanical forces, and its response to internal, cell-generated forces remains poorly understood. Here, using measurements of endogenous Piezo1 activity and traction forces in native cellular conditions, we show that cellular traction forces generate spatially-restricted Piezo1-mediated Ca2+ flickers in the absence of externally-applied mechanical forces. Although Piezo1 channels diffuse readily in the plasma membrane and are widely distributed across the cell, their flicker activity is enriched near force-producing adhesions. The mechanical force that activates Piezo1 arises from Myosin II phosphorylation by Myosin Light Chain Kinase. We propose that Piezo1 Ca2+ flickers allow spatial segregation of mechanotransduction events, and that mobility allows Piezo1 channels to explore a large number of mechanical microdomains and thus respond to a greater diversity of mechanical cues.
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Affiliation(s)
- Kyle L. Ellefsen
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA 92697 USA
| | - Jesse R. Holt
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Center for Complex Biological Systems, UC Irvine, Irvine, CA 92697 USA
| | - Alice C. Chang
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Jamison L. Nourse
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
| | - Janahan Arulmoli
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Department of Biomedical Engineering, UC Irvine, Irvine, CA 92697 USA
| | - Armen H. Mekhdjian
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 USA
| | - Hamid Abuwarda
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
| | - Francesco Tombola
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
| | - Lisa A. Flanagan
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Department of Biomedical Engineering, UC Irvine, Irvine, CA 92697 USA
- Department of Neurology, UC Irvine, Irvine, CA 92697 USA
| | - Alexander R. Dunn
- Department of Chemical Engineering, Stanford University, Stanford, CA 94305 USA
- Stanford Cardiovascular Institute, Stanford School of Medicine, Stanford, CA 94305 USA
| | - Ian Parker
- Department of Neurobiology & Behavior, UC Irvine, Irvine, CA 92697 USA
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
| | - Medha M. Pathak
- Department of Physiology & Biophysics, UC Irvine, Irvine, CA 92697 USA
- Sue and Bill Gross Stem Cell Research Center, UC Irvine, Irvine, CA 92697 USA
- Center for Complex Biological Systems, UC Irvine, Irvine, CA 92697 USA
- Department of Biomedical Engineering, UC Irvine, Irvine, CA 92697 USA
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21
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Matsui TS, Deguchi S. Spatially selective myosin regulatory light chain regulation is absent in dedifferentiated vascular smooth muscle cells but is partially induced by fibronectin and Klf4. Am J Physiol Cell Physiol 2019; 316:C509-C521. [DOI: 10.1152/ajpcell.00251.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The phosphorylation state of myosin regulatory light chain (MRLC) is central to the regulation of contractility that impacts cellular homeostasis and fate decisions. Rho-kinase (ROCK) and myosin light chain kinase (MLCK) are major kinases for MRLC documented to selectively regulate MRLC in a subcellular position-specific manner; specifically, MLCK in some nonmuscle cell types works in the cell periphery to promote migration, while ROCK does so at the central region to sustain contractility. However, it remains unclear whether or not the spatially selective regulation of the MRLC kinases is universally present in other cell types, including dedifferentiated vascular smooth muscle cells (SMCs). Here, we demonstrate the absence of the spatial regulation in dedifferentiated SMCs using both cell lines and primary cells. Thus, our work is distinct from previous reports on cells with migratory potential. We also observed that the spatial regulation is partly induced upon fibronectin stimulation and Krüppel-like factor 4 overexpression. To find clues to the mechanism, we reveal how the phosphorylation state of MRLC is determined within dedifferentiated A7r5 SMCs under the enzymatic competition among three major regulators ROCK, MLCK, and MRLC phosphatase (MLCP). We show that ROCK, but not MLCK, predominantly regulates the MRLC phosphorylation in a manner distinct from previous in vitro-based and in silico-based reports. In this ROCK-dominating cellular system, the contractility at physiological conditions was regulated at the level of MRLC diphosphorylation, because its monophosphorylation is already saturated. Thus, the present study provides insights into the molecular basis underlying the absence of spatial MRLC regulation in dedifferentiated SMCs.
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Affiliation(s)
- Tsubasa S. Matsui
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Shinji Deguchi
- Division of Bioengineering, Graduate School of Engineering Science, Osaka University, Osaka, Japan
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22
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Müller D, Hagenah D, Biswanath S, Coffee M, Kampmann A, Zweigerdt R, Heisterkamp A, Kalies SMK. Femtosecond laser-based nanosurgery reveals the endogenous regeneration of single Z-discs including physiological consequences for cardiomyocytes. Sci Rep 2019; 9:3625. [PMID: 30842507 PMCID: PMC6403391 DOI: 10.1038/s41598-019-40308-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 02/13/2019] [Indexed: 11/24/2022] Open
Abstract
A highly organized cytoskeleton architecture is the basis for continuous and controlled contraction in cardiomyocytes (CMs). Abnormalities in cytoskeletal elements, like the Z-disc, are linked to several diseases. It is challenging to reveal the mechanisms of CM failure, endogenous repair, or mechanical homeostasis on the scale of single cytoskeletal elements. Here, we used a femtosecond (fs) laser to ablate single Z-discs in human pluripotent stem cells (hPSC) -derived CMs (hPSC-CM) and neonatal rat CMs. We show, that CM viability was unaffected by the loss of a single Z-disc. Furthermore, more than 40% of neonatal rat and 68% of hPSC-CMs recovered the Z-disc loss within 24 h. Significant differences to control cells, after the Z-disc loss, in terms of cell perimeter, x- and y-expansion and calcium homeostasis were not found. Only 14 days in vitro old hPSC-CMs reacted with a significant decrease in cell area, x- and y-expansion 24 h past nanosurgery. This demonstrates that CMs can compensate the loss of a single Z-disc and recover a regular sarcomeric pattern during spontaneous contraction. It also highlights the significant potential of fs laser-based nanosurgery to physically micro manipulate CMs to investigate cytoskeletal functions and organization of single elements.
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Affiliation(s)
- Dominik Müller
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany. .,REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany. .,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany.
| | - Dorian Hagenah
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany.,REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Santoshi Biswanath
- REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany.,Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiac, Thoracic, Transplantation and Vascular Surgery (HTTG), Hannover Medical, School, Hannover, Germany
| | - Michelle Coffee
- REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany.,Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiac, Thoracic, Transplantation and Vascular Surgery (HTTG), Hannover Medical, School, Hannover, Germany
| | - Andreas Kampmann
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany.,Clinic for Cranio-Maxillo-Facial Surgery, Hannover Medical School, Hannover, Germany
| | - Robert Zweigerdt
- REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany.,Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiac, Thoracic, Transplantation and Vascular Surgery (HTTG), Hannover Medical, School, Hannover, Germany
| | - Alexander Heisterkamp
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany.,REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Stefan M K Kalies
- Institute of Quantum Optics, Leibniz University Hannover, Hannover, Germany.,REBIRTH-Cluster of Excellence, Hannover Medical School, Hannover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
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23
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Wang P, Liang J, Shi LZ, Wang Y, Zhang P, Ouyang M, Preece D, Peng Q, Shao L, Fan J, Sun J, Li SS, Berns MW, Zhao H, Wang Y. Visualizing Spatiotemporal Dynamics of Intercellular Mechanotransmission upon Wounding. ACS PHOTONICS 2018; 5:3565-3574. [PMID: 31069245 PMCID: PMC6502247 DOI: 10.1021/acsphotonics.8b00383] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
During cell-to-cell communications, the interplay between physical and biochemical cues is essential for informational exchange and functional coordination, especially in multicellular organisms. However, it remains a challenge to visualize intercellular signaling dynamics in single live cells. Here, we report a photonic approach, based on laser microscissors and Förster resonance energy transfer (FRET) microscopy, to study intercellular signaling transmission. First, using our high-throughput screening platform, we developed a highly sensitive FRET-based biosensor (SCAGE) for Src kinase, a key regulator of intercellular interactions and signaling cascades. Notably, SCAGE showed a more than 40-fold sensitivity enhancement than the original biosensor in live mammalian cells. Next, upon local severance of physical intercellular connections by femtosecond laser pulses, SCAGE enabled the visualization of a transient Src activation across neighboring cells. Lastly, we found that this observed transient Src activation following the loss of cell-cell contacts depends on the passive structural support of cytoskeleton but not on the active actomyosin contractility. Hence, by precisely introducing local physical perturbations and directly visualizing spatiotemporal transmission of ensuing signaling events, our integrated approach could be broadly applied to mimic and investigate the wounding process at single-cell resolutions. This integrated approach with highly sensitive FRET-based biosensors provides a unique system to advance our in-depth understanding of molecular mechanisms underlying the physical-biochemical basis of intercellular coupling and wounding processes.
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Affiliation(s)
- Pengzhi Wang
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Jing Liang
- Department of Chemical and Biomolecular Engineering and Carl R. Woese Institute for Genomic Biology
| | - Linda Z. Shi
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Yi Wang
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Ping Zhang
- Institute of Mechanobiology and Biomedical Engineering, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Mingxing Ouyang
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Daryl Preece
- Department of NanoEngineering, University of California, San Diego, La Jolla, California 92093, United States
| | - Qin Peng
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Lunan Shao
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Jason Fan
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
| | - Jie Sun
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Shawn S. Li
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, Ontario Canada N6A 5C1
- Children’s Health Research Institute, 800 Commissioners Road East, London, Ontario Canada N6C 2 V5
| | - Michael W. Berns
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
- Beckman Laser Institute and Medical Clinic, University of California, Irvine, California 92612, United States
- Department of Developmental and Cell Biology, School of Biological Sciences, and Department of Biomedical Engineering, University of California, Irvine, Irvine, California 92617, United States
| | - Huimin Zhao
- Department of Chemical and Biomolecular Engineering and Carl R. Woese Institute for Genomic Biology
| | - Yingxiao Wang
- Department of Bioengineering, University of California, San Diego, La Jolla, California 92093, United States
- Institute of Engineering in Medicine, University of California, San Diego, La Jolla, California 92093, United States
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24
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Hagenah D, Heisterkamp A, Kalies S. Effects of cell state and staining on femtosecond laser nanosurgery. JOURNAL OF BIOPHOTONICS 2018; 11:e201700344. [PMID: 29460488 DOI: 10.1002/jbio.201700344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 02/16/2018] [Indexed: 06/08/2023]
Abstract
Femtosecond laser nanosurgery enables precise manipulation of subcellular elements to study regeneration. However, currently it is not frequently employed-probably because of its unknown consequences on the whole cell level. To better understand the associated biological response of the cell, especially in the context of different cell states and cell staining, we manipulated C2C12 myoblasts and myotubes, which were either unstained (nicotinamide adenine dinucleotide signal) or stained with MitoTracker Red. Both signals overlap well and stain similar areas in untreated cells. We chose 3 different cutting lengths and performed surgery in the cytosol along the major cell axis. The cuts resealed within several minutes independent of the cutting length. We analyzed cell area, perimeter, major and minor axis on long term. We observed significant changes in the cell area and perimeter, dependent on the staining and more pronounced in differentiated myotubes. We conclude, that laser parameters must be chosen carefully, depending on the staining of the cell, its (differentiation) state, and the extent of the cut region, such that unwanted cell responses can be avoided. Laser manipulation of C2C12 myotubes with small ablation (0.8 μm) and large ablation (3.0 μm). While small damages recover, larger damages lead to elimination from the syncytium. Scale bar: 20 μm.
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Affiliation(s)
- Dorian Hagenah
- Institute of Quantum Optics, Leibniz Universität Hannover, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Cluster of Excellence REBIRTH, Hannover, Germany
| | - Alexander Heisterkamp
- Institute of Quantum Optics, Leibniz Universität Hannover, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Cluster of Excellence REBIRTH, Hannover, Germany
| | - Stefan Kalies
- Institute of Quantum Optics, Leibniz Universität Hannover, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
- Cluster of Excellence REBIRTH, Hannover, Germany
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25
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Lee S, Kassianidou E, Kumar S. Actomyosin stress fiber subtypes have unique viscoelastic properties and roles in tension generation. Mol Biol Cell 2018; 29:1992-2004. [PMID: 29927349 PMCID: PMC6232976 DOI: 10.1091/mbc.e18-02-0106] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Actomyosin stress fibers (SFs) support cell shape and migration by directing intracellular tension to the extracellular matrix (ECM) via focal adhesions. Migrating cells exhibit three SF subtypes (dorsal SFs, transverse arcs, and ventral SFs), which differ in their origin, location, and ECM connectivity. While each subtype is hypothesized to play unique structural roles, this idea has not been directly tested at the single-SF level. Here, we interrogate the mechanical properties of single SFs of each subtype based on their retraction kinetics following laser incision. While each SF subtype bears distinct mechanical properties, these properties are highly interdependent, with incision of dorsal fibers producing centripetal recoil of adjacent transverse arcs and the retraction of incised transverse arcs being limited by attachment points to dorsal SFs. These observations hold whether cells are allowed to spread freely or are confined to crossbow ECM patterns. Consistent with this interdependence, subtype-specific knockdown of dorsal SFs (palladin) or transverse arcs (mDia2) influences ventral SF retraction. These altered mechanics are partially phenocopied in cells cultured on ECM microlines that preclude assembly of dorsal SFs and transverse arcs. Our findings directly demonstrate that different SF subtypes play distinct roles in generating tension and form a mechanically interdependent network.
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Affiliation(s)
- Stacey Lee
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762.,Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762
| | - Elena Kassianidou
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762.,Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762
| | - Sanjay Kumar
- UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762.,Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720-1762.,Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720-1762
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26
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Hughes AJ, Miyazaki H, Coyle MC, Zhang J, Laurie MT, Chu D, Vavrušová Z, Schneider RA, Klein OD, Gartner ZJ. Engineered Tissue Folding by Mechanical Compaction of the Mesenchyme. Dev Cell 2017; 44:165-178.e6. [PMID: 29290586 DOI: 10.1016/j.devcel.2017.12.004] [Citation(s) in RCA: 116] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Revised: 09/22/2017] [Accepted: 12/01/2017] [Indexed: 01/08/2023]
Abstract
Many tissues fold into complex shapes during development. Controlling this process in vitro would represent an important advance for tissue engineering. We use embryonic tissue explants, finite element modeling, and 3D cell-patterning techniques to show that mechanical compaction of the extracellular matrix during mesenchymal condensation is sufficient to drive tissue folding along programmed trajectories. The process requires cell contractility, generates strains at tissue interfaces, and causes patterns of collagen alignment around and between condensates. Aligned collagen fibers support elevated tensions that promote the folding of interfaces along paths that can be predicted by modeling. We demonstrate the robustness and versatility of this strategy for sculpting tissue interfaces by directing the morphogenesis of a variety of folded tissue forms from patterns of mesenchymal condensates. These studies provide insight into the active mechanical properties of the embryonic mesenchyme and establish engineering strategies for more robustly directing tissue morphogenesis ex vivo.
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Affiliation(s)
- Alex J Hughes
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA; Center for Cellular Construction, University of California, San Francisco, CA 94143, USA
| | - Hikaru Miyazaki
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA; Graduate Program in Bioengineering, University of California, Berkeley, CA, USA; Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA
| | - Maxwell C Coyle
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jesse Zhang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA; Graduate Program in Bioengineering, University of California, Berkeley, CA, USA; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94143, USA
| | - Matthew T Laurie
- Department of Biochemistry and Molecular Biology, University of California, San Francisco, CA 94143, USA
| | - Daniel Chu
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143, USA
| | - Zuzana Vavrušová
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143, USA
| | - Richard A Schneider
- Department of Orthopaedic Surgery, University of California, San Francisco, CA 94143, USA
| | - Ophir D Klein
- Program in Craniofacial Biology and Department of Orofacial Sciences, University of California, San Francisco, CA 94143, USA; Department of Pediatrics and Institute for Human Genetics, University of California, San Francisco, CA 94143, USA
| | - Zev J Gartner
- Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143, USA; Center for Cellular Construction, University of California, San Francisco, CA 94143, USA; Graduate Program in Bioengineering, University of California, Berkeley, CA, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
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27
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Kassianidou E, Hughes JH, Kumar S. Activation of ROCK and MLCK tunes regional stress fiber formation and mechanics via preferential myosin light chain phosphorylation. Mol Biol Cell 2017; 28:3832-3843. [PMID: 29046396 PMCID: PMC5739298 DOI: 10.1091/mbc.e17-06-0401] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 10/10/2017] [Accepted: 10/12/2017] [Indexed: 01/21/2023] Open
Abstract
Graded induction of regulatory light chain (RLC) activators MLCK and ROCK were used to explore the relationship between RLC phosphorylation and actin-myosin stress fiber viscoelasticity. MLCK controls peripheral stress fiber mechanics by monophosphorylation of RLC, whereas ROCK acts on central stress fibers via diphosphorylation. The assembly and mechanics of actomyosin stress fibers (SFs) depend on myosin regulatory light chain (RLC) phosphorylation, which is driven by myosin light chain kinase (MLCK) and Rho-associated kinase (ROCK). Although previous work suggests that MLCK and ROCK control distinct pools of cellular SFs, it remains unclear how these kinases differ in their regulation of RLC phosphorylation or how phosphorylation influences individual SF mechanics. Here, we combine genetic approaches with biophysical tools to explore relationships between kinase activity, RLC phosphorylation, SF localization, and SF mechanics. We show that graded MLCK overexpression increases RLC monophosphorylation (p-RLC) in a graded manner and that this p-RLC localizes to peripheral SFs. Conversely, graded ROCK overexpression preferentially increases RLC diphosphorylation (pp-RLC), with pp-RLC localizing to central SFs. Interrogation of single SFs with subcellular laser ablation reveals that MLCK and ROCK quantitatively regulate the viscoelastic properties of peripheral and central SFs, respectively. The effects of MLCK and ROCK on single-SF mechanics may be correspondingly phenocopied by overexpression of mono- and diphosphomimetic RLC mutants. Our results point to a model in which MLCK and ROCK regulate peripheral and central SF viscoelastic properties through mono- and diphosphorylation of RLC, offering new quantitative connections between kinase activity, RLC phosphorylation, and SF viscoelasticity.
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Affiliation(s)
- Elena Kassianidou
- Department of Bioengineering.,UC Berkeley-UCSF Graduate Program in Bioengineering, and
| | - Jasmine H Hughes
- Department of Bioengineering.,UC Berkeley-UCSF Graduate Program in Bioengineering, and
| | - Sanjay Kumar
- Department of Bioengineering .,UC Berkeley-UCSF Graduate Program in Bioengineering, and.,Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720
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28
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Geometry and network connectivity govern the mechanics of stress fibers. Proc Natl Acad Sci U S A 2017; 114:2622-2627. [PMID: 28213499 DOI: 10.1073/pnas.1606649114] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Actomyosin stress fibers (SFs) play key roles in driving polarized motility and generating traction forces, yet little is known about how tension borne by an individual SF is governed by SF geometry and its connectivity to other cytoskeletal elements. We now address this question by combining single-cell micropatterning with subcellular laser ablation to probe the mechanics of single, geometrically defined SFs. The retraction length of geometrically isolated SFs after cutting depends strongly on SF length, demonstrating that longer SFs dissipate more energy upon incision. Furthermore, when cell geometry and adhesive spacing are fixed, cell-to-cell heterogeneities in SF dissipated elastic energy can be predicted from varying degrees of physical integration with the surrounding network. We apply genetic, pharmacological, and computational approaches to demonstrate a causal and quantitative relationship between SF connectivity and mechanics for patterned cells and show that similar relationships hold for nonpatterned cells allowed to form cell-cell contacts in monolayer culture. Remarkably, dissipation of a single SF within a monolayer induces cytoskeletal rearrangements in cells long distances away. Finally, stimulation of cell migration leads to characteristic changes in network connectivity that promote SF bundling at the cell rear. Our findings demonstrate that SFs influence and are influenced by the networks in which they reside. Such higher order network interactions contribute in unexpected ways to cell mechanics and motility.
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29
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Abstract
Mechanotransduction is the process through which cells survey the mechanical properties of their environment, convert these mechanical inputs into biochemical signals, and modulate their phenotype in response. These mechanical inputs, which may be encoded in the form of extracellular matrix stiffness, dimensionality, and adhesion, all strongly influence cell morphology, migration, and fate decisions. One mechanism through which cells on planar or pseudo-planar matrices exert tensile forces and interrogate microenvironmental mechanics is through stress fibers, which are bundles composed of actin filaments and, in most cases, non-muscle myosin II filaments. Stress fibers form a continuous structural network that is mechanically coupled to the extracellular matrix through focal adhesions. Furthermore, myosin-driven contractility plays a central role in the ability of stress fibers to sense matrix mechanics and generate tension. Here, we review the distinct roles that non-muscle myosin II plays in driving mechanosensing and focus specifically on motility. In a closely related discussion, we also describe stress fiber classification schemes and the differing roles of various myosin isoforms in each category. Finally, we briefly highlight recent studies exploring mechanosensing in three-dimensional environments, in which matrix content, structure, and mechanics are often tightly interrelated. Stress fibers and the myosin motors therein represent an intriguing and functionally important biological system in which mechanics, biochemistry, and architecture all converge.
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Affiliation(s)
- Stacey Lee
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA
| | - Sanjay Kumar
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA; UC Berkeley-UCSF Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA, 94720, USA
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30
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Katta S, Krieg M, Goodman MB. Feeling force: physical and physiological principles enabling sensory mechanotransduction. Annu Rev Cell Dev Biol 2016; 31:347-71. [PMID: 26566115 DOI: 10.1146/annurev-cellbio-100913-013426] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Organisms as diverse as microbes, roundworms, insects, and mammals detect and respond to applied force. In animals, this ability depends on ionotropic force receptors, known as mechanoelectrical transduction (MeT) channels, that are expressed by specialized mechanoreceptor cells embedded in diverse tissues and distributed throughout the body. These cells mediate hearing, touch, and proprioception and play a crucial role in regulating organ function. Here, we attempt to integrate knowledge about the architecture of mechanoreceptor cells and their sensory organs with principles of cell mechanics, and we consider how engulfing tissues contribute to mechanical filtering. We address progress in the quest to identify the proteins that form MeT channels and to understand how these channels are gated. For clarity and convenience, we focus on sensory mechanobiology in nematodes, fruit flies, and mice. These themes are emphasized: asymmetric responses to applied forces, which may reflect anisotropy of the structure and mechanics of sensory mechanoreceptor cells, and proteins that function as MeT channels, which appear to have emerged many times through evolution.
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Affiliation(s)
- Samata Katta
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305;
| | - Michael Krieg
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305;
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305;
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31
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Liu AP. Biophysical Tools for Cellular and Subcellular Mechanical Actuation of Cell Signaling. Biophys J 2016; 111:1112-1118. [PMID: 27456131 DOI: 10.1016/j.bpj.2016.02.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/17/2016] [Accepted: 02/01/2016] [Indexed: 10/24/2022] Open
Abstract
The ability to spatially control cell signaling can help resolve fundamental biological questions. Optogenetic and chemical dimerization techniques along with fluorescent biosensors to report cell signaling activities have enabled researchers to both visualize and perturb biochemistry in living cells. A number of approaches based on mechanical actuation using force-field gradients have emerged as complementary technologies to manipulate cell signaling in real time. This review covers several technologies, including optical, magnetic, and acoustic control of cell signaling and behavior and highlights some studies that have led to novel insights. I will also discuss some future direction on repurposing mechanosensitive channel for mechanical actuation of spatial cell signaling.
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Affiliation(s)
- Allen P Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan; Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan; Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, Michigan; Biophysics Program, University of Michigan, Ann Arbor, Michigan.
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32
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Labouesse C, Gabella C, Meister JJ, Vianay B, Verkhovsky AB. Microsurgery-aided in-situ force probing reveals extensibility and viscoelastic properties of individual stress fibers. Sci Rep 2016; 6:23722. [PMID: 27025817 PMCID: PMC4812326 DOI: 10.1038/srep23722] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Accepted: 03/11/2016] [Indexed: 11/10/2022] Open
Abstract
Actin-myosin filament bundles (stress fibers) are critical for tension generation and cell shape, but their mechanical properties are difficult to access. Here we propose a novel approach to probe individual peripheral stress fibers in living cells through a microsurgically generated opening in the cytoplasm. By applying large deformations with a soft cantilever we were able to fully characterize the mechanical response of the fibers and evaluate their tension, extensibility, elastic and viscous properties.
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Affiliation(s)
- Céline Labouesse
- Laboratory of Cell Biophysics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Chiara Gabella
- Laboratory of Cell Biophysics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Jean-Jacques Meister
- Laboratory of Cell Biophysics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Benoît Vianay
- Laboratory of Cell Biophysics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Alexander B Verkhovsky
- Laboratory of Cell Biophysics, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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33
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Afasizheva A, Devine A, Tillman H, Fung KL, Vieira WD, Blehm BH, Kotobuki Y, Busby B, Chen EI, Tanner K. Mitogen-activated protein kinase signaling causes malignant melanoma cells to differentially alter extracellular matrix biosynthesis to promote cell survival. BMC Cancer 2016; 16:186. [PMID: 26944546 PMCID: PMC4779217 DOI: 10.1186/s12885-016-2211-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 02/22/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Intrinsic and acquired resistance to drug therapies remains a challenge for malignant melanoma patients. Intratumoral heterogeneities within the tumor microenvironment contribute additional complexity to the determinants of drug efficacy and acquired resistance. METHODS We use 3D biomimetic platforms to understand dynamics in extracellular matrix (ECM) biogenesis following pharmaceutical intervention against mitogen-activated protein kinases (MAPK) signaling. We further determined temporal evolution of secreted ECM components by isogenic melanoma cell clones. RESULTS We found that the cell clones differentially secrete and assemble a myriad of ECM molecules into dense fibrillar and globular networks. We show that cells can modulate their ECM biosynthesis in response to external insults. Fibronectin (FN) is one of the key architectural components, modulating the efficacy of a broad spectrum of drug therapies. Stable cell lines engineered to secrete minimal levels of FN showed a concomitant increase in secretion of Tenascin-C and became sensitive to BRAF(V600E) and ERK inhibition as clonally- derived 3D tumor aggregates. These cells failed to assemble exogenous FN despite maintaining the integrin machinery to facilitate cell- ECM cross-talk. We determined that only clones that increased FN production via p38 MAPK and β1 integrin survived drug treatment. CONCLUSIONS These data suggest that tumor cells engineer drug resistance by altering their ECM biosynthesis. Therefore, drug treatment may induce ECM biosynthesis, contributing to de novo resistance.
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Affiliation(s)
- Anna Afasizheva
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
| | - Alexus Devine
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
| | - Heather Tillman
- Laboratories of Genitourinary Cancer Pathogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, 20892, MD, USA.
| | - King Leung Fung
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
| | - Wilfred D Vieira
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
| | - Benjamin H Blehm
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
| | - Yorihisa Kotobuki
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
| | - Ben Busby
- National Centers for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, 20892, MD, USA.
| | - Emily I Chen
- Proteomics Shared Resource at the Herbert Irving Comprehensive Cancer Center & Department of Pharmacology, Columbia University Medical Center, New York, 10032, NY, USA.
| | - Kandice Tanner
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 37 Convent Dr., Bethesda, MD, 20892, USA.
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34
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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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35
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Vigliotti A, McMeeking RM, Deshpande VS. Simulation of the cytoskeletal response of cells on grooved or patterned substrates. J R Soc Interface 2015; 12:rsif.2014.1320. [PMID: 25762648 DOI: 10.1098/rsif.2014.1320] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
We analyse the response of osteoblasts on grooved substrates via a model that accounts for the cooperative feedback between intracellular signalling, focal adhesion development and stress fibre contractility. The grooved substrate is modelled as a pattern of alternating strips on which the cell can adhere and strips on which adhesion is inhibited. The coupled modelling scheme is shown to capture some key experimental observations including (i) the observation that osteoblasts orient themselves randomly on substrates with groove pitches less than about 150 nm but they align themselves with the direction of the grooves on substrates with larger pitches and (ii) actin fibres bridge over the grooves on substrates with groove pitches less than about 150 nm but form a network of fibres aligned with the ridges, with nearly no fibres across the grooves, for substrates with groove pitches greater than about 300 nm. Using the model, we demonstrate that the degree of bridging of the stress fibres across the grooves, and consequently the cell orientation, is governed by the diffusion of signalling proteins activated at the focal adhesion sites on the ridges. For large groove pitches, the signalling proteins are dephosphorylated before they can reach the regions of the cell above the grooves and hence stress fibres cannot form in those parts of the cell. On the other hand, the stress fibre activation signal diffuses to a reasonably spatially homogeneous level on substrates with small groove pitches and hence stable stress fibres develop across the grooves in these cases. The model thus rationalizes the responsiveness of osteoblasts to the topography of substrates based on the complex feedback involving focal adhesion formation on the ridges, the triggering of signalling pathways by these adhesions and the activation of stress fibre networks by these signals.
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Affiliation(s)
- A Vigliotti
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
| | - R M McMeeking
- Department of Mechanical and Environmental Engineering, University of California, Santa Barbara, CA 93106, USA School of Engineering, University of Aberdeen, King's College, Aberdeen AB24 3UE, UK
| | - V S Deshpande
- Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, UK
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36
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Rolando M, Stefani C, Doye A, Acosta MI, Visvikis O, Yevick HG, Buchrieser C, Mettouchi A, Bassereau P, Lemichez E. Contractile actin cables induced by Bacillus anthracis lethal toxin depend on the histone acetylation machinery. Cytoskeleton (Hoboken) 2015; 72:542-56. [PMID: 26403219 DOI: 10.1002/cm.21256] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 09/18/2015] [Accepted: 09/22/2015] [Indexed: 12/25/2022]
Abstract
It remains a challenge to decode the molecular basis of the long-term actin cytoskeleton rearrangements that are governed by the reprogramming of gene expression. Bacillus anthracis lethal toxin (LT) inhibits mitogen-activated protein kinase (MAPK) signaling, thereby modulating gene expression, with major consequences for actin cytoskeleton organization and the loss of endothelial barrier function. Using a laser ablation approach, we characterized the contractile and tensile mechanical properties of LT-induced stress fibers. These actin cables resist pulling forces that are transmitted at cell-matrix interfaces and at cell-cell discontinuous adherens junctions. We report that treating the cells with trichostatin A (TSA), a broad range inhibitor of histone deacetylases (HDACs), or with MS-275, which targets HDAC1, 2 and 3, induces stress fibers. LT decreased the cellular levels of HDAC1, 2 and 3 and reduced the global HDAC activity in the nucleus. Both the LT and TSA treatments induced Rnd3 expression, which is required for the LT-mediated induction of actin stress fibers. Furthermore, we reveal that treating the LT-intoxicated cells with garcinol, an inhibitor of histone acetyl-transferases (HATs), disrupts the stress fibers and limits the monolayer barrier dysfunctions. These data demonstrate the importance of modulating the flux of protein acetylation in order to control actin cytoskeleton organization and the endothelial cell monolayer barrier.
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Affiliation(s)
- Monica Rolando
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France.,Biologie Des Bactéries Intracellulaires, Institut Pasteur, Paris, France.,UMR 3525, CNRS, Paris, France
| | - Caroline Stefani
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France.,Immunology Program, Benaroya Research Institute at Virginia Mason, Seattle, WA 98101, USA
| | - Anne Doye
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France
| | - Maria I Acosta
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France
| | - Orane Visvikis
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France
| | - Hannah G Yevick
- Institut Curie-Centre de Recherche, Membrane and Cell Functions Group; CNRS UMR 168, Physico-Chimie Curie, Université Pierre et Marie Curie, 26 Rue d'ulm, Paris Cedex 05, 75248, France
| | - Carmen Buchrieser
- Biologie Des Bactéries Intracellulaires, Institut Pasteur, Paris, France.,UMR 3525, CNRS, Paris, France
| | - Amel Mettouchi
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France
| | - Patricia Bassereau
- Institut Curie-Centre de Recherche, Membrane and Cell Functions Group; CNRS UMR 168, Physico-Chimie Curie, Université Pierre et Marie Curie, 26 Rue d'ulm, Paris Cedex 05, 75248, France
| | - Emmanuel Lemichez
- Microbial Toxins in Host-Pathogen Interactions, Equipe Labellisée La Ligue Contre Le Cancer, INSERM, U1065, Centre Méditerranéen De Médecine Moléculaire (C3M), 151 Route St Antoine de Ginestière, BP 2 3194, 06204 Nice Cedex, France.,UFR Médecine, IFR50, Faculté De Médecine, Université De Nice-Sophia Antipolis, Nice, France
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Ma Z, Wu YS, Mak AF. Rheological behavior of actin stress fibers in myoblasts after nanodissection: Effects of oxidative stress. Biorheology 2015; 52:225-34. [DOI: 10.3233/bir-14041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Affiliation(s)
- Zili Ma
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Yiqian Shirley Wu
- Biomedical Engineering Programme, The Chinese University of Hong Kong, Hong Kong, China
| | - Arthur F.T. Mak
- Department of Electronic Engineering, The Chinese University of Hong Kong, Hong Kong, China
- Biomedical Engineering Programme, The Chinese University of Hong Kong, Hong Kong, China
- Division of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong, China
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38
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Differential Contributions of Nonmuscle Myosin II Isoforms and Functional Domains to Stress Fiber Mechanics. Sci Rep 2015; 5:13736. [PMID: 26336830 PMCID: PMC4559901 DOI: 10.1038/srep13736] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2015] [Accepted: 08/04/2015] [Indexed: 01/14/2023] Open
Abstract
While is widely acknowledged that nonmuscle myosin II (NMMII) enables stress fibers (SFs) to generate traction forces against the extracellular matrix, little is known about how specific NMMII isoforms and functional domains contribute to SF mechanics. Here we combine biophotonic and genetic approaches to address these open questions. First, we suppress the NMMII isoforms MIIA and MIIB and apply femtosecond laser nanosurgery to ablate and investigate the viscoelastic retraction of individual SFs. SF retraction dynamics associated with MIIA and MIIB suppression qualitatively phenocopy our earlier measurements in the setting of Rho kinase (ROCK) and myosin light chain kinase (MLCK) inhibition, respectively. Furthermore, fluorescence imaging and photobleaching recovery reveal that MIIA and MIIB are enriched in and more stably localize to ROCK- and MLCK-controlled central and peripheral SFs, respectively. Additional domain-mapping studies surprisingly reveal that deletion of the head domain speeds SF retraction, which we ascribe to reduced drag from actomyosin crosslinking and frictional losses. We propose a model in which ROCK/MIIA and MLCK/MIIB functionally regulate common pools of SFs, with MIIA crosslinking and motor functions jointly contributing to SF retraction dynamics and cellular traction forces.
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39
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Gavara N, Chadwick RS. Relationship between cell stiffness and stress fiber amount, assessed by simultaneous atomic force microscopy and live-cell fluorescence imaging. Biomech Model Mechanobiol 2015. [PMID: 26206449 PMCID: PMC4869747 DOI: 10.1007/s10237-015-0706-9] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Actomyosin stress fibers, one of the main components of the cell’s cytoskeleton, provide mechanical stability to adherent cells by applying and transmitting tensile forces onto the extracellular matrix (ECM) at the sites of cell–ECM adhesion. While it is widely accepted that changes in spatial and temporal distribution of stress fibers affect the cell’s mechanical properties, there is no quantitative knowledge on how stress fiber amount and organization directly modulate cell stiffness. We address this key open question by combining atomic force microscopy with simultaneous fluorescence imaging of living cells, and combine for the first time reliable quantitative parameters obtained from both techniques. We show that the amount of myosin and (to a lesser extent) actin assembled in stress fibers directly modulates cell stiffness in adherent mouse fibroblasts (NIH3T3). In addition, the spatial distribution of stress fibers has a second-order modulatory effect. In particular, the presence of either fibers located in the cell periphery, aligned fibers or thicker fibers gives rise to reinforced cell stiffness. Our results provide basic and significant information that will help design optimal protocols to regulate the mechanical properties of adherent cells via pharmacological interventions that alter stress fiber assembly or via micropatterning techniques that restrict stress fiber spatial organization.
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Affiliation(s)
- Núria Gavara
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 3NS, UK.
| | - Richard S Chadwick
- Auditory Mechanics Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Building 10 Rm. 5D49, 10 Center Drive, MSC-1417, Bethesda, MD, 20892, USA
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40
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Kassianidou E, Kumar S. A biomechanical perspective on stress fiber structure and function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:3065-74. [PMID: 25896524 DOI: 10.1016/j.bbamcr.2015.04.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 04/05/2015] [Accepted: 04/08/2015] [Indexed: 01/11/2023]
Abstract
Stress fibers are actomyosin-based bundles whose structural and contractile properties underlie numerous cellular processes including adhesion, motility and mechanosensing. Recent advances in high-resolution live-cell imaging and single-cell force measurement have dramatically sharpened our understanding of the assembly, connectivity, and evolution of various specialized stress fiber subpopulations. This in turn has motivated interest in understanding how individual stress fibers generate tension and support cellular structure and force generation. In this review, we discuss approaches for measuring the mechanical properties of single stress fibers. We begin by discussing studies conducted in cell-free settings, including strategies based on isolation of intact stress fibers and reconstitution of stress fiber-like structures from purified components. We then discuss measurements obtained in living cells based both on inference of stress fiber properties from whole-cell mechanical measurements (e.g., atomic force microscopy) and on direct interrogation of single stress fibers (e.g., subcellular laser nanosurgery). We conclude by reviewing various mathematical models of stress fiber function that have been developed based on these experimental measurements. An important future challenge in this area will be the integration of these sophisticated biophysical measurements with the field's increasingly detailed molecular understanding of stress fiber assembly, dynamics, and signal transduction. This article is part of a Special Issue entitled: Mechanobiology.
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Affiliation(s)
- Elena Kassianidou
- Department of Bioengineering, University of California, Berkeley, United States
| | - Sanjay Kumar
- Department of Bioengineering, University of California, Berkeley, United States.
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41
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Soiné JRD, Brand CA, Stricker J, Oakes PW, Gardel ML, Schwarz US. Model-based traction force microscopy reveals differential tension in cellular actin bundles. PLoS Comput Biol 2015; 11:e1004076. [PMID: 25748431 PMCID: PMC4352062 DOI: 10.1371/journal.pcbi.1004076] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/08/2014] [Indexed: 01/02/2023] Open
Abstract
Adherent cells use forces at the cell-substrate interface to sense and respond to the physical properties of their environment. These cell forces can be measured with traction force microscopy which inverts the equations of elasticity theory to calculate them from the deformations of soft polymer substrates. We introduce a new type of traction force microscopy that in contrast to traditional methods uses additional image data for cytoskeleton and adhesion structures and a biophysical model to improve the robustness of the inverse procedure and abolishes the need for regularization. We use this method to demonstrate that ventral stress fibers of U2OS-cells are typically under higher mechanical tension than dorsal stress fibers or transverse arcs. Adherent cells respond very sensitively not only to biochemical, but also to physical properties of their environment. For example, it has been shown that stem cell differentiation can be guided by substrate rigidity, which is sensed by cells by actively pulling on their environment with actomyosin-generated forces. A commonly used method to measure cell forces during essential biological processes is traction force microscopy, which uses the deformations of a soft elastic substrate to calculate cell forces. However, the standard setup for traction force microscopy suffers from mathematical limitations in calculating forces from displacements. In order to improve this method, we combine image data and biophysical modelling to arrive at a procedure which is more robust and in addition allows us to make statements about the force distribution not only at the cell-substrate interface, but also inside the cell. Here we demonstrate this approach for the contractility of actin stress fibers, which we investigate experimentally with U2OS-cells and theoretically with an active cable network model.
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Affiliation(s)
- Jérôme R. D. Soiné
- Institute for Theoretical Physics and BioQuant, Heidelberg University, Heidelberg, Germany
| | - Christoph A. Brand
- Institute for Theoretical Physics and BioQuant, Heidelberg University, Heidelberg, Germany
| | - Jonathan Stricker
- Institute for Biophysical Dynamics, Department of Physics, and The James Franck Institute, University of Chicago, Chicago, United States of America
| | - Patrick W. Oakes
- Institute for Biophysical Dynamics, Department of Physics, and The James Franck Institute, University of Chicago, Chicago, United States of America
| | - Margaret L. Gardel
- Institute for Biophysical Dynamics, Department of Physics, and The James Franck Institute, University of Chicago, Chicago, United States of America
| | - Ulrich S. Schwarz
- Institute for Theoretical Physics and BioQuant, Heidelberg University, Heidelberg, Germany
- * E-mail:
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42
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Nie W, Wei MT, Ou-Yang HD, Jedlicka SS, Vavylonis D. Formation of contractile networks and fibers in the medial cell cortex through myosin-II turnover, contraction, and stress-stabilization. Cytoskeleton (Hoboken) 2015; 72:29-46. [PMID: 25641802 DOI: 10.1002/cm.21207] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 12/31/2014] [Indexed: 12/24/2022]
Abstract
The morphology of adhered cells depends crucially on the formation of a contractile meshwork of parallel and cross-linked fibers along the contacting surface. The motor activity and minifilament assembly of non-muscle myosin-II is an important component of cortical cytoskeletal remodeling during mechanosensing. We used experiments and computational modeling to study cortical myosin-II dynamics in adhered cells. Confocal microscopy was used to image the medial cell cortex of HeLa cells stably expressing myosin regulatory light chain tagged with GFP (MRLC-GFP). The distribution of MRLC-GFP fibers and focal adhesions was classified into three types of network morphologies. Time-lapse movies show: myosin foci appearance and disappearance; aligning and contraction; stabilization upon alignment. Addition of blebbistatin, which perturbs myosin motor activity, leads to a reorganization of the cortical networks and to a reduction of contractile motions. We quantified the kinetics of contraction, disassembly and reassembly of myosin networks using spatio-temporal image correlation spectroscopy (STICS). Coarse-grained numerical simulations include bipolar minifilaments that contract and align through specified interactions as basic elements. After assuming that minifilament turnover decreases with increasing contractile stress, the simulations reproduce stress-dependent fiber formation in between focal adhesions above a threshold myosin concentration. The STICS correlation function in simulations matches the function measured in experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness.
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Affiliation(s)
- Wei Nie
- Department of Physics, Lehigh University, Bethlehem, Pennsylvania
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43
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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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44
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Hirata H, Gupta M, Vedula SRK, Lim CT, Ladoux B, Sokabe M. Actomyosin bundles serve as a tension sensor and a platform for ERK activation. EMBO Rep 2014; 16:250-7. [PMID: 25550404 DOI: 10.15252/embr.201439140] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Tensile forces generated by stress fibers drive signal transduction events at focal adhesions. Here, we report that stress fibers per se act as a platform for tension-induced activation of biochemical signals. The MAP kinase, ERK is activated on stress fibers in a myosin II-dependent manner. In myosin II-inhibited cells, uniaxial stretching of cell adhesion substrates restores ERK activation on stress fibers. By quantifying myosin II- or mechanical stretch-mediated tensile forces in individual stress fibers, we show that ERK activation on stress fibers correlates positively with tensile forces acting on the fibers, indicating stress fibers as a tension sensor in ERK activation. Myosin II-dependent ERK activation is also observed on actomyosin bundles connecting E-cadherin clusters, thus suggesting that actomyosin bundles, in general, work as a platform for tension-dependent ERK activation.
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Affiliation(s)
- Hiroaki Hirata
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | - Mukund Gupta
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore
| | | | - Chwee Teck Lim
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore Department of Biomedical Engineering, National University of Singapore, Singapore, Singapore Department of Mechanical Engineering, National University of Singapore, Singapore, Singapore
| | - Benoit Ladoux
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore Institut Jacques Monod (IJM), CNRS UMR 7592 Université Paris Diderot, Paris, France
| | - Masahiro Sokabe
- Mechanobiology Institute, National University of Singapore, Singapore, Singapore Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, Nagoya, Japan
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45
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Cell rigidity and shape override CD47's "self"-signaling in phagocytosis by hyperactivating myosin-II. Blood 2014; 125:542-52. [PMID: 25411427 DOI: 10.1182/blood-2014-06-585299] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A macrophage engulfs another cell or foreign particle in an adhesive process that often activates myosin-II, unless the macrophage also engages "marker of self" CD47 that inhibits myosin. For many cell types, adhesion-induced activation of myosin-II is maximized by adhesion to a rigid rather than a flexible substrate. Here we demonstrate that rigidity of a phagocytosed cell also hyperactivates myosin-II, which locally overwhelms self-signaling at a phagocytic synapse. Cell stiffness is one among many factors including shape that changes in erythropoiesis, in senescence and in diseases ranging from inherited anemias and malaria to cancer. Controlled stiffening of normal human red blood cells (RBCs) in different shapes does not compromise CD47's interaction with the macrophage self-recognition receptor signal regulatory protein alpha (SIRPA). Uptake of antibody-opsonized RBCs is always fastest with rigid RBC discocytes, which also show that maximal active myosin-II at the synapse can dominate self-signaling by CD47. Rigid but rounded RBC stomatocytes signal self better than rigid RBC discocytes, highlighting the effects of shape on CD47 inhibition. Physical properties of phagocytic targets thus regulate self signaling, as is relevant to erythropoiesis, to clearance of rigid RBCs after blood storage, clearance of rigid pathological cells such as thalassemic or sickle cells, and even to interactions of soft/stiff cancer cells with macrophages.
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46
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Elosegui-Artola A, Jorge-Peñas A, Moreno-Arotzena O, Oregi A, Lasa M, García-Aznar JM, De Juan-Pardo EM, Aldabe R. Image analysis for the quantitative comparison of stress fibers and focal adhesions. PLoS One 2014; 9:e107393. [PMID: 25269086 PMCID: PMC4182299 DOI: 10.1371/journal.pone.0107393] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 08/15/2014] [Indexed: 01/08/2023] Open
Abstract
Actin stress fibers (SFs) detect and transmit forces to the extracellular matrix through focal adhesions (FAs), and molecules in this pathway determine cellular behavior. Here, we designed two different computational tools to quantify actin SFs and the distribution of actin cytoskeletal proteins within a normalized cellular morphology. Moreover, a systematic cell response comparison between the control cells and those with impaired actin cytoskeleton polymerization was performed to demonstrate the reliability of the tools. Indeed, a variety of proteins that were present within the string beginning at the focal adhesions (vinculin) up to the actin SFs contraction (non-muscle myosin II (NMMII)) were analyzed. Finally, the software used allows for the quantification of the SFs based on the relative positions of FAs. Therefore, it provides a better insight into the cell mechanics and broadens the knowledge of the nature of SFs.
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Affiliation(s)
- Alberto Elosegui-Artola
- Tissue Engineering and Biomaterials Unit, Centro de Estudios e Investigaciones Técnicas and Tecnun, University of Navarra, San Sebastian, Spain
| | - Alvaro Jorge-Peñas
- Tissue Engineering and Biomaterials Unit, Centro de Estudios e Investigaciones Técnicas and Tecnun, University of Navarra, San Sebastian, Spain
| | - Oihana Moreno-Arotzena
- Multiscale in Mechanical and Biological Engineering, Aragón Institute of Engineering Research, Universidad de Zaragoza, Zaragoza, Spain
| | - Amaia Oregi
- Tissue Engineering and Biomaterials Unit, Centro de Estudios e Investigaciones Técnicas and Tecnun, University of Navarra, San Sebastian, Spain
| | - Marta Lasa
- Gene Therapy and Hepatology Area, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
| | - José Manuel García-Aznar
- Multiscale in Mechanical and Biological Engineering, Aragón Institute of Engineering Research, Universidad de Zaragoza, Zaragoza, Spain
| | - Elena M. De Juan-Pardo
- Tissue Engineering and Biomaterials Unit, Centro de Estudios e Investigaciones Técnicas and Tecnun, University of Navarra, San Sebastian, Spain
- * E-mail: (RA); (EMDJ)
| | - Rafael Aldabe
- Gene Therapy and Hepatology Area, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain
- * E-mail: (RA); (EMDJ)
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47
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Tondon A, Kaunas R. The direction of stretch-induced cell and stress fiber orientation depends on collagen matrix stress. PLoS One 2014; 9:e89592. [PMID: 24586898 PMCID: PMC3933569 DOI: 10.1371/journal.pone.0089592] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 01/21/2014] [Indexed: 01/04/2023] Open
Abstract
Cell structure depends on both matrix strain and stiffness, but their interactive effects are poorly understood. We investigated the interactive roles of matrix properties and stretching patterns on cell structure by uniaxially stretching U2OS cells expressing GFP-actin on silicone rubber sheets supporting either a surface-adsorbed coating or thick hydrogel of type-I collagen. Cells and their actin stress fibers oriented perpendicular to the direction of cyclic stretch on collagen-coated sheets, but oriented parallel to the stretch direction on collagen gels. There was significant alignment parallel to the direction of a steady increase in stretch for cells on collagen gels, while cells on collagen-coated sheets did not align in any direction. The extent of alignment was dependent on both strain rate and duration. Stretch-induced alignment on collagen gels was blocked by the myosin light-chain kinase inhibitor ML7, but not by the Rho-kinase inhibitor Y27632. We propose that active orientation of the actin cytoskeleton perpendicular and parallel to direction of stretch on stiff and soft substrates, respectively, are responses that tend to maintain intracellular tension at an optimal level. Further, our results indicate that cells can align along directions of matrix stress without collagen fibril alignment, indicating that matrix stress can directly regulate cell morphology.
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Affiliation(s)
- Abhishek Tondon
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America
| | - Roland Kaunas
- Department of Biomedical Engineering, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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48
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Structure and biomechanics of the endothelial transcellular circumferential invasion array in tumor invasion. PLoS One 2014; 9:e89758. [PMID: 24587014 PMCID: PMC3933692 DOI: 10.1371/journal.pone.0089758] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Accepted: 01/24/2014] [Indexed: 11/19/2022] Open
Abstract
Cancer cells breach the endothelium not only through cell-cell junctions but also via individual endothelial cells (ECs), or transcellular invasion. The underlying EC forms a circular structure around the transcellular invasion pore that is dependent on myosin light chain kinase (MLCK) and myosin II regulatory light chain (RLC) phosphorylation. Here we offer mechanistic insights into transcellular invasive array formation amid persistent tensile force from activated EC myosin. Fluorescence recovery after photobleaching (FRAP) experiments, sarcomeric distance measurements using super-resolution microscopy and electron microscopy provide details about the nature of the myosin II invasion array. To probe the relationship between biomechanical forces and the tension required to maintain the curvature of contractile filaments, we targeted individual actin-myosin fibers at the invasion site for photoablation. We showed that adjacent filaments rapidly replace the ablat11ed structures. We propose that the transcellular circumferential invasion array (TCIA) provides the necessary constraint within the EC to blunt the radial compression from the invading cancer cell.
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49
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Nagayama K, Yamazaki S, Yahiro Y, Matsumoto T. Estimation of the mechanical connection between apical stress fibers and the nucleus in vascular smooth muscle cells cultured on a substrate. J Biomech 2014; 47:1422-9. [PMID: 24548337 DOI: 10.1016/j.jbiomech.2014.01.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/17/2014] [Accepted: 01/18/2014] [Indexed: 11/26/2022]
Abstract
Actin stress fibers (SFs) generate intercellular tension and play important roles in cellular mechanotransduction processes and the regulation of various cellular functions. We recently found, in vascular smooth muscle cells (SMCs) cultured on a substrate, that the apical SFs running across the top surface of the nucleus have a mechanical connection with the cell nucleus and that their internal tension is transmitted directly to the nucleus. However, the effects of the connecting conditions and binding forces between SFs and the nucleus on force transmission processes are unclear at this stage. Here, we estimated the mechanical connection between apical SFs and the nucleus in SMCs, taking into account differences in the contractility of individual SFs, using experimental and numerical approaches. First, we classified apical SFs in SMCs according to their morphological characteristics: one subset appeared pressed onto the apical surface of the nucleus (pressed SFs), and the other appeared to be smoothly attached to the nuclear surface (attached SFs). We then dissected these SFs by laser irradiation to release the pretension, observed the dynamic behavior of the dissected SFs and the nucleus, and estimated the pretension of the SFs and the connection strength between the SFs and the nucleus by using a simple viscoelastic model. We found that pressed SFs generated greater contractile force and were more firmly connected to the nuclear surface than were attached SFs. We also observed line-like concentration of the nuclear membrane protein nesprin 1 and perinuclear DNA that was significantly located along the pressed SFs. These results indicate that the internal tension of pressed SFs is transmitted to the nucleus more efficiently than that of attached SFs, and that pressed SFs have significant roles in the regulation of the nuclear morphology and rearrangement of intranuclear DNA.
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Affiliation(s)
- Kazuaki Nagayama
- Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Omohi College, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
| | - Sho Yamazaki
- Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Omohi College, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Yuki Yahiro
- Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Omohi College, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan
| | - Takeo Matsumoto
- Biomechanics Laboratory, Department of Mechanical Engineering, Nagoya Institute of Technology, Omohi College, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
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50
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14-3-3σ stabilizes a complex of soluble actin and intermediate filament to enable breast tumor invasion. Proc Natl Acad Sci U S A 2013; 110:E3937-44. [PMID: 24067649 DOI: 10.1073/pnas.1315022110] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The protein 14-3-3σ (stratifin) is frequently described as a tumor suppressor silenced in about 80% of breast tumors. Intriguingly, we show that 14-3-3σ expression, which in normal breast is localized to the myoepithelial cells, tracks with malignant phenotype in two models of basal-like breast cancer progression, and in patients, it is associated with basal-like subtype and poor clinical outcome. We characterized a mechanism by which 14-3-3σ guides breast tumor invasion by integrating cytoskeletal dynamics: it stabilizes a complex of solubilized actin and intermediate filaments to maintain a pool of "bioavailable" complexes for polarized assembly during migration. We show that formation of the actin/cytokeratin/14-3-3σ complex and cellular migration are regulated by PKCζ-dependent phosphorylation, a finding that could form the basis for intervention in aggressive breast carcinomas expressing 14-3-3σ. Our data suggest that the biology of this protein is important in cellular movement and is contingent on breast cancer subtype.
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