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Demosthene B, Kravchuk P, Harmon CL, Kalae A, Kang EH. Small organic osmolytes accelerate actin filament assembly and stiffen filaments. Cytoskeleton (Hoboken) 2024. [PMID: 39276026 DOI: 10.1002/cm.21927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 08/27/2024] [Accepted: 09/03/2024] [Indexed: 09/16/2024]
Abstract
Actin filament assembly and mechanics are crucial for maintenance of cell structure, motility, and division. Actin filament assembly occurs in a crowded intracellular environment consisting of various types of molecules, including small organic molecules known as osmolytes. Ample evidence highlights the protective functions of osmolytes such as trimethylamine-N-oxide (TMAO), including their effects on protein stability and their ability to counteract cellular osmotic stress. Yet, how TMAO affects individual actin filament assembly dynamics and mechanics is not well understood. We hypothesize that, owing to its protective nature, TMAO will enhance filament dynamics and stiffen actin filaments due to increased stability. In this study, we investigate osmolyte-dependent actin filament assembly and bending mechanics by measuring filament elongation rates, steady-state filament lengths, and bending persistence lengths in the presence of TMAO using total internal reflection fluorescence microscopy and pyrene assays. Our results demonstrate that TMAO increases filament elongation rates as well as steady-state average filament lengths, and enhances filament bending stiffness. Together, these results will help us understand how small organic osmolytes modulate cytoskeletal protein assembly and mechanics in living cells.
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Affiliation(s)
- Bryan Demosthene
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
- Burnett School of Biomedical Sciences, University of Central Florida, Orlando, Florida, USA
| | - Pavlo Kravchuk
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
| | - Connor L Harmon
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
| | - Abdulrazak Kalae
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
| | - Ellen H Kang
- NanoScience Technology Center, University of Central Florida, Orlando, Florida, USA
- Department of Physics, University of Central Florida, Orlando, Florida, USA
- Department of Materials Science and Engineering, University of Central Florida, Orlando, Florida, USA
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2
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Carl AG, Reynolds MJ, Gurel PS, Phua DY, Sun X, Mei L, Hamilton K, Takagi Y, Noble AJ, Sellers JR, Alushin GM. Myosin forces elicit an F-actin structural landscape that mediates mechanosensitive protein recognition. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.15.608188. [PMID: 39185238 PMCID: PMC11343212 DOI: 10.1101/2024.08.15.608188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/27/2024]
Abstract
Cells mechanically interface with their surroundings through cytoskeleton-linked adhesions, allowing them to sense physical cues that instruct development and drive diseases such as cancer. Contractile forces generated by myosin motor proteins mediate these mechanical signal transduction processes through unclear protein structural mechanisms. Here, we show that myosin forces elicit structural changes in actin filaments (F-actin) that modulate binding by the mechanosensitive adhesion protein α-catenin. Using correlative cryo-fluorescence microscopy and cryo-electron tomography, we identify F-actin featuring domains of nanoscale oscillating curvature at cytoskeleton-adhesion interfaces enriched in zyxin, a marker of actin-myosin generated traction forces. We next introduce a reconstitution system for visualizing F-actin in the presence of myosin forces with cryo-electron microscopy, which reveals morphologically similar superhelical F-actin spirals. In simulations, transient forces mimicking tugging and release of filaments by motors produce spirals, supporting a mechanistic link to myosin's ATPase mechanochemical cycle. Three-dimensional reconstruction of spirals uncovers extensive asymmetric remodeling of F-actin's helical lattice. This is recognized by α-catenin, which cooperatively binds along individual strands, preferentially engaging interfaces featuring extended inter-subunit distances while simultaneously suppressing rotational deviations to regularize the lattice. Collectively, we find that myosin forces can deform F-actin, generating a conformational landscape that is detected and reciprocally modulated by a mechanosensitive protein, providing a direct structural glimpse at active force transduction through the cytoskeleton.
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Affiliation(s)
- Ayala G. Carl
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
- Tri-Institutional Program in Chemical Biology, The Rockefeller University, New York, NY, USA
| | - Matthew J. Reynolds
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Pinar S. Gurel
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Donovan Y.Z. Phua
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Xiaoyu Sun
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Lin Mei
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
- Tri-Institutional Program in Chemical Biology, The Rockefeller University, New York, NY, USA
| | - Keith Hamilton
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
| | - Yasuharu Takagi
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Alex J. Noble
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, USA
| | - James R. Sellers
- Laboratory of Molecular Physiology, Cell and Developmental Biology Center, National Heart, Lung, and Blood Institute, NIH, Bethesda, MD, USA
| | - Gregory M. Alushin
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, New York, NY, USA
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3
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Mukadum F, Ccoa WJP, Hocky GM. Molecular simulation approaches to probing the effects of mechanical forces in the actin cytoskeleton. Cytoskeleton (Hoboken) 2024; 81:318-327. [PMID: 38334204 PMCID: PMC11310368 DOI: 10.1002/cm.21837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 02/10/2024]
Abstract
In this article we give our perspective on the successes and promise of various molecular and coarse-grained simulation approaches to probing the effect of mechanical forces in the actin cytoskeleton.
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Affiliation(s)
- Fatemah Mukadum
- Department of Chemistry, New York University, New York, NY 10003, USA
| | | | - Glen M. Hocky
- Department of Chemistry, New York University, New York, NY 10003, USA
- Simons Center for Computational Physical Chemistry, New York, NY 10003, USA
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4
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Xu XP, Cao W, Swift MF, Pandit NG, Huehn AE, Sindelar CV, De La Cruz EM, Hanein D, Volkmann N. High-resolution yeast actin structures indicate the molecular mechanism of actin filament stiffening by cations. Commun Chem 2024; 7:164. [PMID: 39079963 PMCID: PMC11289367 DOI: 10.1038/s42004-024-01243-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Accepted: 07/10/2024] [Indexed: 08/02/2024] Open
Abstract
Actin filament assembly and the regulation of its mechanical properties are fundamental processes essential for eukaryotic cell function. Residue E167 in vertebrate actins forms an inter-subunit salt bridge with residue K61 of the adjacent subunit. Saccharomyces cerevisiae actin filaments are more flexible than vertebrate filaments and have an alanine at this position (A167). Substitution of this alanine for a glutamic acid (A167E) confers Saccharomyces cerevisiae actin filaments with salt-dependent stiffness similar to vertebrate actins. We developed an optimized cryogenic electron microscopy workflow refining sample preparation and vitrification to obtain near-atomic resolution structures of wild-type and A167E mutant Saccharomyces cerevisiae actin filaments. The difference between these structures allowed us to pinpoint the potential binding site of a filament-associated cation that controls the stiffness of the filaments in vertebrate and A167E Saccharomyces cerevisiae actins. Through an analysis of previously published high-resolution reconstructions of vertebrate actin filaments, along with a newly determined high-resolution vertebrate actin structure in the absence of potassium, we identified a unique peak near residue 167 consistent with the binding of a magnesium ion. Our findings show how magnesium can contribute to filament stiffening by directly bridging actin subunits and allosterically affecting the orientation of the DNase-I binding loop of actin, which plays a regulatory role in modulating actin filament stiffness and interactions with regulatory proteins.
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Affiliation(s)
- Xiao-Ping Xu
- Scintillon Institute, 6868 Nancy Ridge Drive, San Diego, CA, 92121, USA
| | - Wenxiang Cao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Mark F Swift
- Scintillon Institute, 6868 Nancy Ridge Drive, San Diego, CA, 92121, USA
| | - Nandan G Pandit
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Andrew E Huehn
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Charles V Sindelar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Dorit Hanein
- Department of Chemistry and Biochemistry and Department of Biological Engineering, University of California, Santa Barbara, CA, 93106, USA.
| | - Niels Volkmann
- Department of Biological Engineering, Department of Electrical and Computer Engineering, Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, 93106, USA.
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5
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Conboy JP, Istúriz Petitjean I, van der Net A, Koenderink GH. How cytoskeletal crosstalk makes cells move: Bridging cell-free and cell studies. BIOPHYSICS REVIEWS 2024; 5:021307. [PMID: 38840976 PMCID: PMC11151447 DOI: 10.1063/5.0198119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 05/13/2024] [Indexed: 06/07/2024]
Abstract
Cell migration is a fundamental process for life and is highly dependent on the dynamical and mechanical properties of the cytoskeleton. Intensive physical and biochemical crosstalk among actin, microtubules, and intermediate filaments ensures their coordination to facilitate and enable migration. In this review, we discuss the different mechanical aspects that govern cell migration and provide, for each mechanical aspect, a novel perspective by juxtaposing two complementary approaches to the biophysical study of cytoskeletal crosstalk: live-cell studies (often referred to as top-down studies) and cell-free studies (often referred to as bottom-up studies). We summarize the main findings from both experimental approaches, and we provide our perspective on bridging the two perspectives to address the open questions of how cytoskeletal crosstalk governs cell migration and makes cells move.
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Affiliation(s)
- James P. Conboy
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Irene Istúriz Petitjean
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Anouk van der Net
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Gijsje H. Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
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6
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Alisafaei F, Mandal K, Saldanha R, Swoger M, Yang H, Shi X, Guo M, Hehnly H, Castañeda CA, Janmey PA, Patteson AE, Shenoy VB. Vimentin is a key regulator of cell mechanosensing through opposite actions on actomyosin and microtubule networks. Commun Biol 2024; 7:658. [PMID: 38811770 PMCID: PMC11137025 DOI: 10.1038/s42003-024-06366-4] [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: 11/14/2022] [Accepted: 05/21/2024] [Indexed: 05/31/2024] Open
Abstract
The cytoskeleton is a complex network of interconnected biopolymers consisting of actin filaments, microtubules, and intermediate filaments. These biopolymers work in concert to transmit cell-generated forces to the extracellular matrix required for cell motility, wound healing, and tissue maintenance. While we know cell-generated forces are driven by actomyosin contractility and balanced by microtubule network resistance, the effect of intermediate filaments on cellular forces is unclear. Using a combination of theoretical modeling and experiments, we show that vimentin intermediate filaments tune cell stress by assisting in both actomyosin-based force transmission and reinforcement of microtubule networks under compression. We show that the competition between these two opposing effects of vimentin is regulated by the microenvironment stiffness. These results reconcile seemingly contradictory results in the literature and provide a unified description of vimentin's effects on the transmission of cell contractile forces to the extracellular matrix.
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Affiliation(s)
- Farid Alisafaei
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Department of Mechanical and Industrial Engineering, New Jersey Institute of Technology, Newark, NJ, 07102, USA
| | - Kalpana Mandal
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA, 19104, USA
| | - Renita Saldanha
- Physics Department, Syracuse University, Syracuse, NY, 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA
| | - Maxx Swoger
- Physics Department, Syracuse University, Syracuse, NY, 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA
| | - Haiqian Yang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Xuechen Shi
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA, 19104, USA
| | - Ming Guo
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Heidi Hehnly
- Department of Biology, Syracuse University, Syracuse, NY, 13244, USA
| | - Carlos A Castañeda
- Departments of Biology and Chemistry, Syracuse University, Syracuse, NY, 13244, USA
- Interdisciplinary Neuroscience Program, Syracuse University, Syracuse, NY, 13244, USA
| | - Paul A Janmey
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA
- Institute for Medicine and Engineering, University of Pennsylvania, 3340 Smith Walk, Philadelphia, PA, 19104, USA
- Departments of Physiology, and Physics & Astronomy, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Alison E Patteson
- Physics Department, Syracuse University, Syracuse, NY, 13244, USA
- BioInspired Institute, Syracuse University, Syracuse, NY, 13244, USA
| | - Vivek B Shenoy
- Center for Engineering Mechanobiology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
- Department of Materials Science and Engineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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7
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Heyn JCJ, Rädler JO, Falcke M. Mesenchymal cell migration on one-dimensional micropatterns. Front Cell Dev Biol 2024; 12:1352279. [PMID: 38694822 PMCID: PMC11062138 DOI: 10.3389/fcell.2024.1352279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 03/29/2024] [Indexed: 05/04/2024] Open
Abstract
Quantitative studies of mesenchymal cell motion are important to elucidate cytoskeleton function and mechanisms of cell migration. To this end, confinement of cell motion to one dimension (1D) significantly simplifies the problem of cell shape in experimental and theoretical investigations. Here we review 1D migration assays employing micro-fabricated lanes and reflect on the advantages of such platforms. Data are analyzed using biophysical models of cell migration that reproduce the rich scenario of morphodynamic behavior found in 1D. We describe basic model assumptions and model behavior. It appears that mechanical models explain the occurrence of universal relations conserved across different cell lines such as the adhesion-velocity relation and the universal correlation between speed and persistence (UCSP). We highlight the unique opportunity of reproducible and standardized 1D assays to validate theory based on statistical measures from large data of trajectories and discuss the potential of experimental settings embedding controlled perturbations to probe response in migratory behavior.
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Affiliation(s)
- Johannes C. J. Heyn
- Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Joachim O. Rädler
- Fakultät für Physik, Ludwig-Maximilians-Universität München (LMU), Munich, Germany
| | - Martin Falcke
- Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- Department of Physics, Humboldt University, Berlin, Germany
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8
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Chavali SS, Chou SZ, Cao W, Pollard TD, De La Cruz EM, Sindelar CV. Cryo-EM structures reveal how phosphate release from Arp3 weakens actin filament branches formed by Arp2/3 complex. Nat Commun 2024; 15:2059. [PMID: 38448439 PMCID: PMC10918085 DOI: 10.1038/s41467-024-46179-x] [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: 07/11/2023] [Accepted: 02/16/2024] [Indexed: 03/08/2024] Open
Abstract
Arp2/3 complex nucleates branched actin filaments for cell and organelle movements. Here we report a 2.7 Å resolution cryo-EM structure of the mature branch junction formed by S. pombe Arp2/3 complex that provides details about interactions with both mother and daughter filaments. We determine a second structure at 3.2 Å resolution with the phosphate analog BeFx bound with ADP to Arp3 and ATP bound to Arp2. In this ADP-BeFx transition state the outer domain of Arp3 is rotated 2° toward the mother filament compared with the ADP state and makes slightly broader contacts with actin in both the mother and daughter filaments. Thus, dissociation of Pi from the ADP-Pi transition state reduces the interactions of Arp2/3 complex with the actin filaments and may contribute to the lower mechanical stability of mature branch junctions with ADP bound to the Arps. Our structures also reveal that the mother filament in contact with Arp2/3 complex is slightly bent and twisted, consistent with the preference of Arp2/3 complex binding curved actin filaments. The small degree of twisting constrains models of actin filament mechanics.
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Affiliation(s)
- Sai Shashank Chavali
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA
| | - Steven Z Chou
- Department of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center, Farmington, CT, 06030, USA
| | - Wenxiang Cao
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA
| | - Thomas D Pollard
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
- Department of Molecular Cellular and Developmental Biology, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
- Department of Cell Biology, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
- Department of Molecular and Cell Biology, University of California, 638 Barker Hall, Berkeley, CA, 94720-3200, USA.
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
| | - Charles V Sindelar
- Department of Molecular Biophysics and Biochemistry, Yale University, PO Box 208103, New Haven, CT, 06520-8103, USA.
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9
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Maxian O, Mogilner A. Helical motors and formins synergize to compact chiral filopodial bundles: A theoretical perspective. Eur J Cell Biol 2024; 103:151383. [PMID: 38237507 DOI: 10.1016/j.ejcb.2023.151383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 12/19/2023] [Accepted: 12/30/2023] [Indexed: 01/28/2024] Open
Abstract
Chiral actin bundles have been shown to play an important role in cell dynamics, but our understanding of the molecular mechanisms which combine to generate chirality remains incomplete. To address this, we numerically simulate a crosslinked filopodial bundle under the actions of helical myosin motors and/or formins and examine the collective buckling and twisting of the actin bundle. We first show that a number of proposed mechanisms to buckle polymerizing actin bundles without motor activity fail under biologically-realistic parameters. We then demonstrate that a simplified model of myosin spinning action at the bundle base effectively "braids" the bundle, but cannot control compaction at the fiber tips. Finally, we show that formin-mediated polymerization and motor activity can act synergitically to compact filopodium bundles, as motor activity bends filaments into shapes that activate twist forces induced by formins. Stochastic fluctuations of actin polymerization rates and slower cross linking dynamics both increase buckling and decrease compaction. We discuss implications of our findings for mechanisms of cytoskeletal chirality.
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Affiliation(s)
- Ondrej Maxian
- Courant Institute, New York University, New York, NY 10012, USA; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, IL 60615, USA; Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60615, USA
| | - Alex Mogilner
- Courant Institute, New York University, New York, NY 10012, USA; Department of Biology, New York University, New York, NY 10012, USA.
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10
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Sun ZG, Yadav V, Amiri S, Cao W, De La Cruz EM, Murrell M. Cofilin-mediated actin filament network flexibility facilitates 2D to 3D actomyosin shape change. Eur J Cell Biol 2024; 103:151379. [PMID: 38168598 DOI: 10.1016/j.ejcb.2023.151379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 12/06/2023] [Accepted: 12/16/2023] [Indexed: 01/05/2024] Open
Abstract
The organization of actin filaments (F-actin) into crosslinked networks determines the transmission of mechanical stresses within the cytoskeleton and subsequent changes in cell and tissue shape. Principally mediated by proteins such as α-actinin, F-actin crosslinking increases both network connectivity and rigidity, thereby facilitating stress transmission at low crosslinking yet attenuating transmission at high crosslinker concentration. Here, we engineer a two-dimensional model of the actomyosin cytoskeleton, in which myosin-induced mechanical stresses are controlled by light. We alter the extent of F-actin crosslinking by the introduction of oligomerized cofilin. At pH 6.5, F-actin severing by cofilin is weak, but cofilin bundles and crosslinks filaments. Given its effect of lowering the F-actin bending stiffness, cofilin- crosslinked networks are significantly more flexible and softer in bending than networks crosslinked by α-actinin. Thus, upon local activation of myosin-induced contractile stress, the network bends out-of-plane in contrast to the in-plane compression as observed with networks crosslinked by α-actinin. Here, we demonstrate that local effects on filament mechanics by cofilin introduces novel large-scale network material properties that enable the sculpting of complex shapes in the cell cytoskeleton.
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Affiliation(s)
- Zachary Gao Sun
- Systems Biology Institute, Yale University, West Haven, CT 06516, USA; Department of Physics, Yale University, 217 Prospect Street, New Haven, CT 06511, USA; Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06520, USA
| | - Vikrant Yadav
- Systems Biology Institute, Yale University, West Haven, CT 06516, USA; Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA
| | - Sorosh Amiri
- Systems Biology Institute, Yale University, West Haven, CT 06516, USA; Department of Mechanical Engineering and Material Science, Yale University, New Haven, CT 06511, USA
| | - Wenxiang Cao
- Department of Molecular Biology & Biophysics, Yale University, New Haven, CT 06511, USA
| | - Enrique M De La Cruz
- Department of Molecular Biology & Biophysics, Yale University, New Haven, CT 06511, USA
| | - Michael Murrell
- Systems Biology Institute, Yale University, West Haven, CT 06516, USA; Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA; Department of Physics, Yale University, 217 Prospect Street, New Haven, CT 06511, USA; Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, CT 06520, USA.
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11
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Goode BL, Eskin J, Shekhar S. Mechanisms of actin disassembly and turnover. J Cell Biol 2023; 222:e202309021. [PMID: 37948068 PMCID: PMC10638096 DOI: 10.1083/jcb.202309021] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 10/21/2023] [Accepted: 10/23/2023] [Indexed: 11/12/2023] Open
Abstract
Cellular actin networks exhibit a wide range of sizes, shapes, and architectures tailored to their biological roles. Once assembled, these filamentous networks are either maintained in a state of polarized turnover or induced to undergo net disassembly. Further, the rates at which the networks are turned over and/or dismantled can vary greatly, from seconds to minutes to hours or even days. Here, we review the molecular machinery and mechanisms employed in cells to drive the disassembly and turnover of actin networks. In particular, we highlight recent discoveries showing that specific combinations of conserved actin disassembly-promoting proteins (cofilin, GMF, twinfilin, Srv2/CAP, coronin, AIP1, capping protein, and profilin) work in concert to debranch, sever, cap, and depolymerize actin filaments, and to recharge actin monomers for new rounds of assembly.
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Affiliation(s)
- Bruce L. Goode
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Julian Eskin
- Department of Biology, Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA, USA
| | - Shashank Shekhar
- Departments of Physics, Cell Biology and Biochemistry, Emory University, Atlanta, GA, USA
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12
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Okura K, Matsumoto T, Narita A, Tatsumi H. Mechanical Stress Decreases the Amplitude of Twisting and Bending Fluctuations of Actin Filaments. J Mol Biol 2023; 435:168295. [PMID: 37783285 DOI: 10.1016/j.jmb.2023.168295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 09/08/2023] [Accepted: 09/26/2023] [Indexed: 10/04/2023]
Abstract
A variety of biological roles of mechanical forces have been proposed in cell biology, such as cell signaling pathways for survival, development, growth, and differentiation. Mechanical forces alter the mechanical conditions within cells and their environment, which strongly influences the reorganization of the actin cytoskeleton. Single-molecule imaging studies of actin filaments have led to the hypothesis that the actin filament acts as a mechanosensor; e.g., increases in actin filament tension alter their conformation and affinity for regulatory proteins. However, our understanding of the molecular mechanisms underlying how tension modulates the mechanical behavior of a single actin filament is still incomplete. In this study, a direct measurement of the twisting and bending of a fluorescently labeled single actin filament under different tension levels by force application (0.8-3.4 pN) was performed using single-molecule fluorescence polarization (SMFP) microscopy. The results showed that the amplitude of twisting and bending fluctuations of a single actin filament decreased with increasing tension. Electron micrograph analysis of tensed filaments also revealed that the fluctuations in the crossover length of actin filaments decreased with increasing filament tension. Possible molecular mechanisms underlying these results involving the binding of actin-binding proteins, such as cofilin, to the filament are discussed.
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Affiliation(s)
- Kaoru Okura
- Department of Applied Bioscience, Kanazawa Institute of Technology, Ishikawa, Japan
| | - Tomoharu Matsumoto
- Department of Biological Science, Graduate School of Sciences, Nagoya University, 464-8601 Nagoya, Japan
| | - Akihiro Narita
- Department of Biological Science, Graduate School of Sciences, Nagoya University, 464-8601 Nagoya, Japan
| | - Hitoshi Tatsumi
- Department of Applied Bioscience, Kanazawa Institute of Technology, Ishikawa, Japan.
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Lu C, Zheng J, Yoshitomi T, Kawazoe N, Yang Y, Chen G. How Hydrogel Stiffness Affects Adipogenic Differentiation of Mesenchymal Stem Cells under Controlled Morphology. ACS APPLIED BIO MATERIALS 2023; 6:3441-3450. [PMID: 37061939 DOI: 10.1021/acsabm.3c00159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
Matrix stiffness has been disclosed as an essential regulator of cell fate. However, it is barely studied how the matrix stiffness affects stem cell functions when cell morphology changes. Thus, in this study, the effect of hydrogel stiffness on adipogenic differentiation of human bone-marrow-derived mesenchymal stem cells (hMSCs) with controlled morphology was investigated. Micropatterns of different size and elongation were prepared by a photolithographical micropatterning technique. The hMSCs were cultured on the micropatterns and showed a different spreading area and elongation following the geometry of the underlying micropatterns. The cells with controlled morphology were embedded in agarose hydrogels of different stiffnesses. The cells showed a different level of adipogenic differentiation that was dependent on both hydrogel stiffness and cell morphology. Adipogenic differentiation became strong when the cell spreading area decreased and hydrogel stiffness increased. Adipogenic differentiation did not change with cell elongation. Therefore, cell spreading area and hydrogel stiffness could synergistically affect adipogenic differentiation of hMSCs, while cell elongation did not affect adipogenic differentiation. A change of cell morphology and hydrogel stiffness was accompanied by actin filament alignment that was strongly related to adipogenic differentiation. The results indicated that cell morphology could affect cellular sensitivity to hydrogel stiffness. The results will provide useful information for the elucidation of the interaction of stem cells and their microenvironmental biomechanical cues.
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Affiliation(s)
- Chengyu Lu
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Department of Materials Science and Engineering, Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
| | - Jing Zheng
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Toru Yoshitomi
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Naoki Kawazoe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
| | - Yingnan Yang
- Graduate School of Life and Environment Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Guoping Chen
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
- Department of Materials Science and Engineering, Graduate School of Pure and Applied Science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577, Japan
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