1
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Ren C, Chang Z, Li K, Wang X, Wang D, Xu Y, Li X, Li Q. Impact of uniaxial cyclic stretching on matrix-associated endothelial cell responses. Mater Today Bio 2024; 27:101152. [PMID: 39104901 PMCID: PMC11298614 DOI: 10.1016/j.mtbio.2024.101152] [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: 04/09/2024] [Revised: 06/07/2024] [Accepted: 07/08/2024] [Indexed: 08/07/2024] Open
Abstract
Uniaxial cyclic stretching plays a pivotal role in the fields of tissue engineering and regenerative medicine, influencing cell behaviors and functionality based on physical properties, including matrix morphology and mechanical stimuli. This study delves into the response of endothelial cells to uniaxial cyclic strain within the geometric constraints of micro-nano fibers. Various structural scaffold forms of poly(l-lactide-co-caprolactone) (PLCL), such as flat membranes, randomly oriented fiber membranes, and aligned fiber membranes, were fabricated through solvent casting and electrospinning methods. Our investigation focuses on the morphological variation of endothelial cells under diverse geometric constraints and the mechanical-dependent release of nitric oxide (NO) on oriented fibrous membranes. Our results indicate that while uniaxial cyclic stretching promotes endothelial cell spreading, the anisotropy of the matrix morphology remains the primary driving factor for cell alignment. Additionally, uniaxial cyclic stretching significantly enhances NO release, with a notably stronger effect correlated to the increasing strain amplitude. Importantly, this study reveals that uniaxial cyclic stretching enhances the mRNA expression of key proteins, including talin, vinculin, rac, and nitric oxide synthase (eNOS).
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Affiliation(s)
- Cuihong Ren
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou, 450001, PR China
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
| | - Zhonghua Chang
- Institute of Laser Manufacturing, Henan Academy of Sciences, Zhengzhou, 450046, PR China
| | - Kecheng Li
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou, 450001, PR China
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
| | - Xiaofeng Wang
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou, 450001, PR China
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
| | - Dongfang Wang
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou, 450001, PR China
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
| | - Yiyang Xu
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
| | - Xiaomeng Li
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou, 450001, PR China
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
| | - Qian Li
- School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou, 450001, PR China
- National Center for International Research of Micro-Nano Molding Technology, Zhengzhou University, Zhengzhou, 450001, PR China
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2
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Nietmann P, Kaub K, Suchenko A, Stenz S, Warnecke C, Balasubramanian MK, Janshoff A. Cytosolic actin isoforms form networks with different rheological properties that indicate specific biological function. Nat Commun 2023; 14:7989. [PMID: 38042893 PMCID: PMC10693642 DOI: 10.1038/s41467-023-43653-w] [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: 05/03/2023] [Accepted: 11/15/2023] [Indexed: 12/04/2023] Open
Abstract
The implications of the existence of different actins expressed in epithelial cells for network mechanics and dynamics is investigated by microrheology and confocal imaging. γ-actin predominately found in the apical cortex forms stiffer networks compared to β-actin, which is preferentially organized in stress fibers. We attribute this to selective interactions with Mg2+-ions interconnecting the filaments' N-termini. Bundling propensity of the isoforms is different in the presence of Mg2+-ions, while crosslinkers such as α-actinin, fascin, and heavy meromyosin alter the mechanical response independent of the isoform. In the presence of myosin, β-actin networks show a large number of small contraction foci, while γ-actin displays larger but fewer foci indicative of a stronger interaction with myosin motors. We infer that subtle changes in the amino acid sequence of actin isoforms lead to alterations of the mechanical properties on the network level with potential implications for specific biological functions.
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Affiliation(s)
- Peter Nietmann
- Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, Göttingen, 37077, Germany
| | - Kevin Kaub
- Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, Göttingen, 37077, Germany
- Max Planck School Matter to Life, Max Planck Institute for Medical Research, Jahnstr. 29, Heidelberg, 69120, Germany
| | - Andrejus Suchenko
- Warwick Medical School, University of Warwick, Coventry, CV4 7AL, UK
| | - Susanne Stenz
- Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, Göttingen, 37077, Germany
| | - Claas Warnecke
- Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, Göttingen, 37077, Germany
| | | | - Andreas Janshoff
- Institute of Physical Chemistry, University of Goettingen, Tammannstr. 6, Göttingen, 37077, Germany.
- Max Planck School Matter to Life, Max Planck Institute for Medical Research, Jahnstr. 29, Heidelberg, 69120, Germany.
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3
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Li SH, Xu GK. Topological mechanism in the nonlinear power-law relaxation of cell cortex. Phys Rev E 2023; 108:064408. [PMID: 38243511 DOI: 10.1103/physreve.108.064408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 11/16/2023] [Indexed: 01/21/2024]
Abstract
Different types of cells exhibit a universal power-law rheology, but the mechanism underneath is still unclear. Based on the exponential distribution of actin filament length, we treat the cell cortex as a collection of chains of crosslinkers with exponentially distributed binding energy, and show that the power-law exponent of its stress relaxation should scale with the chain length. Through this model, we are able to explain how the exponent can be regulated by the crosslinker number and imposed strain during cortex relaxation. Network statistics show that the average length of filament-crosslinker chains decreases with the crosslinker number, which endows a denser network with lower exponent. Due to gradual molecular alignment with the stretch direction, the number of effectively stretched crosslinkers in the network is found to increase with the imposed strain. This effective growth in network density diminishes the exponent under large strain. By incorporating the inclined angle of crosslinkers into the model without in-series structure, we show that the exponent cannot be altered by crosslinker rotation directly, refining our previous conjectures. This work may help to understand cellular mechanics from the molecular perspective.
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Affiliation(s)
- Shao-Heng Li
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, State Key Laboratory for Strength and Vibration of Mechanical Structures, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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4
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Shivers JL, Sharma A, MacKintosh FC. Strain-Controlled Critical Slowing Down in the Rheology of Disordered Networks. PHYSICAL REVIEW LETTERS 2023; 131:178201. [PMID: 37955486 DOI: 10.1103/physrevlett.131.178201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/19/2023] [Accepted: 09/25/2023] [Indexed: 11/14/2023]
Abstract
Networks and dense suspensions frequently reside near a boundary between soft (or fluidlike) and rigid (or solidlike) regimes. Transitions between these regimes can be driven by changes in structure, density, or applied stress or strain. In general, near the onset or loss of rigidity in these systems, dissipation-limiting heterogeneous nonaffine rearrangements dominate the macroscopic viscoelastic response, giving rise to diverging relaxation times and power-law rheology. Here, we describe a simple quantitative relationship between nonaffinity and the excess viscosity. We test this nonaffinity-viscosity relationship computationally and demonstrate its rheological consequences in simulations of strained filament networks and dense suspensions. We also predict critical signatures in the rheology of semiflexible and stiff biopolymer networks near the strain stiffening transition.
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Affiliation(s)
- Jordan L Shivers
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
| | - Abhinav Sharma
- Institute of Physics, University of Augsburg, 86159 Augsburg, Germany
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Germany
| | - Fred C MacKintosh
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
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5
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Song J, Holten-Andersen N, McKinley GH. Non-Maxwellian viscoelastic stress relaxations in soft matter. SOFT MATTER 2023; 19:7885-7906. [PMID: 37846782 DOI: 10.1039/d3sm00736g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
Viscoelastic stress relaxation is a basic characteristic of soft matter systems such as colloids, gels, and biological networks. Although the Maxwell model of linear viscoelasticity provides a classical description of stress relaxation, it is often not sufficient for capturing the complex relaxation dynamics of soft matter. In this Tutorial, we introduce and discuss the physics of non-Maxwellian linear stress relaxation as observed in soft materials, the ascribed origins of this effect in different systems, and appropriate models that can be used to capture this relaxation behavior. We provide a basic toolkit that can assist the understanding and modeling of the mechanical relaxation of soft materials for diverse applications.
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Affiliation(s)
- Jake Song
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
- Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
| | - Niels Holten-Andersen
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Bioengineering, Lehigh University, Bethlehem, PA 18015, USA
- Department of Materials Science and Engineering, Lehigh University, Bethlehem, PA 18015, USA
| | - Gareth H McKinley
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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6
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Goldner AN, Fessehaye SM, Rodriguez N, Mapes KA, Osterfield M, Doubrovinski K. Evidence that tissue recoil in the early Drosophila embryo is a passive not active process. Mol Biol Cell 2023; 34:br16. [PMID: 37405768 PMCID: PMC10551697 DOI: 10.1091/mbc.e22-09-0409] [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: 09/08/2022] [Revised: 06/26/2023] [Accepted: 06/28/2023] [Indexed: 07/06/2023] Open
Abstract
Understanding tissue morphogenesis is impossible without knowing the mechanical properties of the tissue being shaped. Although techniques for measuring tissue material properties are continually being developed, methods for determining how individual proteins contribute to mechanical properties are very limited. Here, we developed two complementary techniques for the acute inactivation of spaghetti squash (the Drosophila myosin regulatory light chain), one based on the recently introduced (auxin-inducible degron 2 (AID2) system, and the other based on a novel method for conditional protein aggregation that results in nearly instantaneous protein inactivation. Combining these techniques with rheological measurements, we show that passive material properties of the cellularization-stage Drosophila embryo are essentially unaffected by myosin activity. These results suggest that this tissue is elastic, not predominantly viscous, on the developmentally relevant timescale.
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Affiliation(s)
- Amanda Nicole Goldner
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Salena M. Fessehaye
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Nataly Rodriguez
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kelly Ann Mapes
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Miriam Osterfield
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Konstantin Doubrovinski
- Department of Biophysics and Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390
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7
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Aufderhorst-Roberts A, Staykova M. Scratching beyond the surface - minimal actin assemblies as tools to elucidate mechanical reinforcement and shape change. Emerg Top Life Sci 2022; 6:ETLS20220052. [PMID: 36541184 PMCID: PMC9788373 DOI: 10.1042/etls20220052] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/08/2022] [Accepted: 12/09/2022] [Indexed: 12/24/2022]
Abstract
The interaction between the actin cytoskeleton and the plasma membrane in eukaryotic cells is integral to a large number of functions such as shape change, mechanical reinforcement and contraction. These phenomena are driven by the architectural regulation of a thin actin network, directly beneath the membrane through interactions with a variety of binding proteins, membrane anchoring proteins and molecular motors. An increasingly common approach to understanding the mechanisms that drive these processes is to build model systems from reconstituted lipids, actin filaments and associated actin-binding proteins. Here we review recent progress in this field, with a particular emphasis on how the actin cytoskeleton provides mechanical reinforcement, drives shape change and induces contraction. Finally, we discuss potential future developments in the field, which would allow the extension of these techniques to more complex cellular processes.
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Affiliation(s)
| | - Margarita Staykova
- Centre for Materials Physics, Department of Physics, Durham University, Durham DH1 3LE, U.K
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8
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Li SH, Gao H, Xu GK. Network dynamics of the nonlinear power-law relaxation of cell cortex. Biophys J 2022; 121:4091-4098. [PMID: 36171727 PMCID: PMC9675028 DOI: 10.1016/j.bpj.2022.09.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2022] [Revised: 09/09/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Living cells are known to exhibit universal power-law rheological behaviors, but their underlying biomechanical principles are still not fully understood. Here, we present a network dynamics picture to decipher the nonlinear power-law relaxation of cortical cytoskeleton. Under step strains, we present a scaling relation between instantaneous differential stiffness and external stress as a result of chain reorientation. Then, during the relaxation, we show how the scaling law theoretically originates from an exponential form of cortical disorder, with the scaling exponent decreased by the imposed strain or crosslinker density in the nonlinear regime. We attribute this exponent variation to the molecular realignment along the stretch direction or the transition of network structure from in-series to in-parallel modes, both solidifying the network toward our one-dimensional theoretical limit. In addition, the rebinding of crosslinkers is found to be crucial for moderating the relaxation speed under small strains. Together with the disorder nature, we demonstrate that the structural effects of networks provide a unified interpretation for the nonlinear power-law relaxation of cell cortex, and may help to understand cell mechanics from the molecular scale.
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Affiliation(s)
- Shao-Heng Li
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Huajian Gao
- School of Mechanical and Aerospace Engineering, College of Engineering, Nanyang Technological University, Singapore, Singapore; Institute of High Performance Computing, A(∗)STAR, Singapore, Singapore.
| | - Guang-Kui Xu
- Laboratory for Multiscale Mechanics and Medical Science, Department of Engineering Mechanics, SVL, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an, China.
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9
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Chandrasekaran A, Giniger E, Papoian GA. Nucleation causes an actin network to fragment into multiple high-density domains. Biophys J 2022; 121:3200-3212. [PMID: 35927959 PMCID: PMC9463697 DOI: 10.1016/j.bpj.2022.07.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/20/2021] [Accepted: 07/28/2022] [Indexed: 11/02/2022] Open
Abstract
Actin networks rely on nucleation mechanisms to generate new filaments because spontaneous nucleation is kinetically disfavored. Branching nucleation of actin filaments by actin-related protein (Arp2/3), in particular, is critical for actin self-organization. In this study, we use the simulation platform for active matter MEDYAN to generate 2000 s long stochastic trajectories of actin networks, under varying Arp2/3 concentrations, in reaction volumes of biologically meaningful size (>20 μm3). We find that the dynamics of Arp2/3 increase the abundance of short filaments and increases network treadmilling rate. By analyzing the density fields of F-actin, we find that at low Arp2/3 concentrations, F-actin is organized into a single connected and contractile domain, while at elevated Arp2/3 levels (10 nM and above), such high-density actin domains fragment into smaller domains spanning a wide range of volumes. These fragmented domains are extremely dynamic, continuously merging and splitting, owing to the high treadmilling rate of the underlying actin network. Treating the domain dynamics as a drift-diffusion process, we find that the fragmented state is stochastically favored, and the network state slowly drifts toward the fragmented state with considerable diffusion (variability) in the number of domains. We suggest that tuning the Arp2/3 concentration enables cells to transition from a globally coherent cytoskeleton, whose response involves the entire cytoplasmic network, to a fragmented cytoskeleton, where domains can respond independently to locally varying signals.
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Affiliation(s)
- Aravind Chandrasekaran
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland; National Institutes of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Edward Giniger
- National Institutes of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Garegin A Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland; Institute for Physical Science and Technology, University of Maryland, College Park, Maryland.
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10
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Mulla Y, Avellaneda MJ, Roland A, Baldauf L, Jung W, Kim T, Tans SJ, Koenderink GH. Weak catch bonds make strong networks. NATURE MATERIALS 2022; 21:1019-1023. [PMID: 36008604 PMCID: PMC7613626 DOI: 10.1038/s41563-022-01288-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 05/11/2022] [Indexed: 05/12/2023]
Abstract
Molecular catch bonds are ubiquitous in biology and essential for processes like leucocyte extravasion1 and cellular mechanosensing2. Unlike normal (slip) bonds, catch bonds strengthen under tension. The current paradigm is that this feature provides 'strength on demand3', thus enabling cells to increase rigidity under stress1,4-6. However, catch bonds are often weaker than slip bonds because they have cryptic binding sites that are usually buried7,8. Here we show that catch bonds render reconstituted cytoskeletal actin networks stronger than slip bonds, even though the individual bonds are weaker. Simulations show that slip bonds remain trapped in stress-free areas, whereas weak binding allows catch bonds to mitigate crack initiation by moving to high-tension areas. This 'dissociation on demand' explains how cells combine mechanical strength with the adaptability required for shape change, and is relevant to diseases where catch bonding is compromised7,9, including focal segmental glomerulosclerosis10 caused by the α-actinin-4 mutant studied here. We surmise that catch bonds are the key to create life-like materials.
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Affiliation(s)
- Yuval Mulla
- Living Matter Department, AMOLF, Amsterdam, The Netherlands
- Institute for Biological Physics, University of Cologne, Cologne, Germany
| | - Mario J Avellaneda
- Living Matter Department, AMOLF, Amsterdam, The Netherlands
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Antoine Roland
- Living Matter Department, AMOLF, Amsterdam, The Netherlands
| | - Lucia Baldauf
- Living Matter Department, AMOLF, Amsterdam, The Netherlands
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| | - Wonyeong Jung
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA
| | - Taeyoon Kim
- Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN, USA.
| | - Sander J Tans
- Living Matter Department, AMOLF, Amsterdam, The Netherlands.
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands.
| | - Gijsje H Koenderink
- Living Matter Department, AMOLF, Amsterdam, The Netherlands.
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands.
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11
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Mondal A, Morrison G. Compression-induced buckling of a semiflexible filament in two and three dimensions. J Chem Phys 2022; 157:104903. [DOI: 10.1063/5.0104910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The ability of biomolecules to exert forces on their surroundings or resist compression from the environment is essential in a variety of biologically relevant contexts. For filaments in the low-temperature limit and under a constant compressive force, Euler buckling theory predicts a sudden transition from a compressed to a bent state in these slender rods. In this paper, we use a mean-field theory to show that if a semiflexible chain is compressed at a finite temperature with a fixed end-to-end distance (permitting fluctuations in the compressive forces), it exhibits a continuous phase transition to a buckled state at a critical level of compression. We determine a quantitatively accurate prediction of the transverse position distribution function of the midpoint of the chain that indicates this transition. We find the mean compressive forces are non-monotonic as the extension of the filament varies, consistent with the observation that strongly buckled filaments are less able to bear an external load. We also find that for the fixed extension (isometric) ensemble, the buckling transition does not coincide with the local minimum of the mean force (in contrast to Euler buckling). We also show the theory is highly sensitive to fluctuations in length in two dimensions, and that the buckling transition can still be accurately recovered by accounting for those fluctuations. These predictions may be useful in understanding the behavior of filamentous biomolecules compressed by fluctuating forces, relevant in a variety of biological contexts.
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Affiliation(s)
- Ananya Mondal
- Physics, University of Houston, United States of America
| | - Greg Morrison
- Physics, University of Houston, United States of America
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12
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Abstract
Arrested soft materials such as gels and glasses exhibit a slow stress relaxation with a broad distribution of relaxation times in response to linear mechanical perturbations. Although this macroscopic stress relaxation is an essential feature in the application of arrested systems as structural materials, consumer products, foods, and biological materials, the microscopic origins of this relaxation remain poorly understood. Here, we elucidate the microscopic dynamics underlying the stress relaxation of such arrested soft materials under both quiescent and mechanically perturbed conditions through X-ray photon correlation spectroscopy. By studying the dynamics of a model associative gel system that undergoes dynamical arrest in the absence of aging effects, we show that the mean stress relaxation time measured from linear rheometry is directly correlated to the quiescent superdiffusive dynamics of the microscopic clusters, which are governed by a buildup of internal stresses during arrest. We also show that perturbing the system via small mechanical deformations can result in large intermittent fluctuations in the form of avalanches, which give rise to a broad non-Gaussian spectrum of relaxation modes at short times that is observed in stress relaxation measurements. These findings suggest that the linear viscoelastic stress relaxation in arrested soft materials may be governed by nonlinear phenomena involving an interplay of internal stress relaxations and perturbation-induced intermittent avalanches.
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13
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Head D. Viscoelastic Scaling Regimes for Marginally Rigid Fractal Spring Networks. PHYSICAL REVIEW LETTERS 2022; 129:018001. [PMID: 35841566 DOI: 10.1103/physrevlett.129.018001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 05/06/2022] [Accepted: 06/10/2022] [Indexed: 06/15/2023]
Abstract
A family of marginally rigid (isostatic) spring networks with fractal structure up to a controllable length was devised, and the viscoelastic spectra G^{*}(ω) calculated. Two nontrivial scaling regimes were observed, (i) G^{'}≈G^{''}∝ω^{Δ} at low frequencies, consistent with Δ=1/2, and (ii) G^{'}∝G^{''}∝ω^{Δ^{'}} for intermediate frequencies corresponding to fractal structure, consistent with a theoretical prediction Δ^{'}=(ln3-ln2)/(ln3+ln2). The crossover between these two regimes occurred at lower frequencies for larger fractals in a manner suggesting diffusivelike dispersion. Solid gels generated by introducing internal stresses exhibited similar behavior above a low-frequency cutoff, indicating the relevance of these findings to real-world applications.
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Affiliation(s)
- David Head
- School of Computing, University of Leeds, Leeds LS2 9JT, United Kingdom
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14
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Nietmann P, Bodenschatz JE, Cordes AM, Gottwald J, Rother-Nöding H, Oswald T, Janshoff A. Epithelial cells fluidize upon adhesion but display mechanical homeostasis in the adherent state. Biophys J 2022; 121:361-373. [PMID: 34998827 PMCID: PMC8822618 DOI: 10.1016/j.bpj.2021.12.042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/02/2021] [Accepted: 12/28/2021] [Indexed: 02/03/2023] Open
Abstract
Atomic force microscopy is used to study the viscoelastic properties of epithelial cells in three different states. Force relaxation data are acquired from cells in suspension, adhered but single cells, and polarized cells in a confluent monolayer using different indenter geometries comprising flat bars, pyramidal cones, and spheres. We found that the fluidity of cells increased substantially from the suspended to the adherent state. Along this line, the prestress of suspended cells generated by cortical contractility is also greater than that of cells adhering to a surface. Polarized cells that are part of a confluent monolayer form an apical cap that is soft and fluid enough to respond rapidly to mechanical challenges from wounding, changes in the extracellular matrix, osmotic stress, and external deformation. In contrast to adherent cells, cells in the suspended state show a pronounced dependence of fluidity on the external areal strain. With increasing areal strain, the suspended cells become softer and more fluid. We interpret the results in terms of cytoskeletal remodeling that softens cells in the adherent state to facilitate adhesion and spreading by relieving internal active stress. However, once the cells spread on the surface they maintain their mechanical phenotype displaying viscoelastic homeostasis.
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Affiliation(s)
- Peter Nietmann
- Georg-August Universität, Institute for Physical Chemistry, Göttingen, Germany
| | | | - Andrea M. Cordes
- Georg-August Universität, Institute for Physical Chemistry, Göttingen, Germany
| | - Jannis Gottwald
- Georg-August Universität, Institute for Physical Chemistry, Göttingen, Germany
| | - Helen Rother-Nöding
- Georg-August Universität, Institute for Physical Chemistry, Göttingen, Germany
| | - Tabea Oswald
- Georg-August Universität, Institute for Organic and Biomolecular Chemistry, Göttingen, Germany
| | - Andreas Janshoff
- Georg-August Universität, Institute for Physical Chemistry, Göttingen, Germany,Corresponding author
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15
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Viscoelastic properties of epithelial cells. Biochem Soc Trans 2021; 49:2687-2695. [PMID: 34854895 DOI: 10.1042/bst20210476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 09/16/2021] [Accepted: 10/08/2021] [Indexed: 11/17/2022]
Abstract
Epithelial cells form tight barriers that line both the outer and inner surfaces of organs and cavities and therefore face diverse environmental challenges. The response to these challenges relies on the cells' dynamic viscoelastic properties, playing a pivotal role in many biological processes such as adhesion, growth, differentiation, and motility. Therefore, the cells usually adapt their viscoelastic properties to mirror the environment that determines their fate and vitality. Albeit not a high-throughput method, atomic force microscopy is still among the dominating methods to study the mechanical properties of adherent cells since it offers a broad range of forces from Piconewtons to Micronewtons at biologically significant time scales. Here, some recent work of deformation studies on epithelial cells is reviewed with a focus on viscoelastic models suitable to describe force cycle measurements congruent with the architecture of the actin cytoskeleton. The prominent role of the cortex in the cell's response to external forces is discussed also in the context of isolated cortex extracts on porous surfaces.
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16
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Janshoff A. Viscoelasticity of basal plasma membranes and cortices derived from MDCK II cells. BIOPHYSICAL REPORTS 2021; 1:100024. [PMID: 36425463 PMCID: PMC9680774 DOI: 10.1016/j.bpr.2021.100024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 09/08/2021] [Indexed: 06/16/2023]
Abstract
The mechanical properties of cells are largely determined by the architecture and dynamics of their viscoelastic cortex, which consists of a contractile, cross-linked actin mesh attached to the plasma membrane via linker proteins. Measuring the mechanical properties of adherent, polarized epithelial cells is usually limited to the upper, i.e., apical side, of the cells because of their accessibility on culture dishes. Therefore, less is known about the viscoelastic properties of basal membranes. Here, I investigate the viscoelastic properties of basolateral membranes derived from polarized MDCK II epithelia in response to external deformation and compare them to living cells probed at the apical side. MDCK II cells were grown on porous surfaces to confluence, and the upper cell body was removed via a squirting-lysis protocol. The free-standing, defoliated basal membranes were subject to force indentation and relaxation experiments permitting a precise assessment of cortical viscoelasticity. A new theoretical framework to describe the force cycles is developed and applied to obtain the time-dependent area compressibility modulus of cell cortices from adherent cells. Compared with the viscoelastic response of living cells, the basolateral membranes are substantially less fluid and stiffer but obey to the same universal scaling law if excess area is taken correctly into account.
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Affiliation(s)
- Andreas Janshoff
- Department of Chemistry, Institute of Physical Chemistry, Göttingen
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17
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Maxian O, Peláez RP, Mogilner A, Donev A. Simulations of dynamically cross-linked actin networks: Morphology, rheology, and hydrodynamic interactions. PLoS Comput Biol 2021; 17:e1009240. [PMID: 34871298 PMCID: PMC8675935 DOI: 10.1371/journal.pcbi.1009240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 12/16/2021] [Accepted: 11/12/2021] [Indexed: 12/16/2022] Open
Abstract
Cross-linked actin networks are the primary component of the cell cytoskeleton and have been the subject of numerous experimental and modeling studies. While these studies have demonstrated that the networks are viscoelastic materials, evolving from elastic solids on short timescales to viscous fluids on long ones, questions remain about the duration of each asymptotic regime, the role of the surrounding fluid, and the behavior of the networks on intermediate timescales. Here we perform detailed simulations of passively cross-linked non-Brownian actin networks to quantify the principal timescales involved in the elastoviscous behavior, study the role of nonlocal hydrodynamic interactions, and parameterize continuum models from discrete stochastic simulations. To do this, we extend our recent computational framework for semiflexible filament suspensions, which is based on nonlocal slender body theory, to actin networks with dynamic cross linkers and finite filament lifetime. We introduce a model where the cross linkers are elastic springs with sticky ends stochastically binding to and unbinding from the elastic filaments, which randomly turn over at a characteristic rate. We show that, depending on the parameters, the network evolves to a steady state morphology that is either an isotropic actin mesh or a mesh with embedded actin bundles. For different degrees of bundling, we numerically apply small-amplitude oscillatory shear deformation to extract three timescales from networks of hundreds of filaments and cross linkers. We analyze the dependence of these timescales, which range from the order of hundredths of a second to the actin turnover time of several seconds, on the dynamic nature of the links, solvent viscosity, and filament bending stiffness. We show that the network is mostly elastic on the short time scale, with the elasticity coming mainly from the cross links, and viscous on the long time scale, with the effective viscosity originating primarily from stretching and breaking of the cross links. We show that the influence of nonlocal hydrodynamic interactions depends on the network morphology: for homogeneous meshworks, nonlocal hydrodynamics gives only a small correction to the viscous behavior, but for bundled networks it both hinders the formation of bundles and significantly lowers the resistance to shear once bundles are formed. We use our results to construct three-timescale generalized Maxwell models of the networks.
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Affiliation(s)
- Ondrej Maxian
- Courant Institute, New York University, New York, New York, United States of America
| | - Raúl P Peláez
- Department of Theoretical Condensed Matter Physics, Universidad Autónoma de Madrid, Madrid, Spain
| | - Alex Mogilner
- Courant Institute, New York University, New York, New York, United States of America.,Department of Biology, New York University, New York, New York, United States of America
| | - Aleksandar Donev
- Courant Institute, New York University, New York, New York, United States of America
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18
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Fraccia TP, Zanchetta G. Liquid–liquid crystalline phase separation in biomolecular solutions. Curr Opin Colloid Interface Sci 2021. [DOI: 10.1016/j.cocis.2021.101500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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19
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Chen S, Broedersz CP, Markovich T, MacKintosh FC. Nonlinear stress relaxation of transiently crosslinked biopolymer networks. Phys Rev E 2021; 104:034418. [PMID: 34654176 DOI: 10.1103/physreve.104.034418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 08/22/2021] [Indexed: 11/07/2022]
Abstract
A long-standing puzzle in the rheology of living cells is the origin of the experimentally observed long-time stress relaxation. The mechanics of the cell is largely dictated by the cytoskeleton, which is a biopolymer network consisting of transient crosslinkers, allowing for stress relaxation over time. Moreover, these networks are internally stressed due to the presence of molecular motors. In this work we propose a theoretical model that uses a mode-dependent mobility to describe the stress relaxation of such prestressed transient networks. Our theoretical predictions agree favorably with experimental data of reconstituted cytoskeletal networks and may provide an explanation for the slow stress relaxation observed in cells.
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Affiliation(s)
- Sihan Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
| | - Chase P Broedersz
- Department of Physics and Astronomy, Vrije Universiteit Amsterdam, 1081 HV Amsterdam, The Netherlands.,Arnold-Sommerfeld-Center for Theoretical Physics and Center for NanoScience, Ludwig-Maximilians-Universität München, D-80333 München, Germany
| | - Tomer Markovich
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
| | - Fred C MacKintosh
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA.,Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA.,Department of Chemistry, Rice University, Houston, Texas 77005, USA
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20
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Andreu I, Falcones B, Hurst S, Chahare N, Quiroga X, Le Roux AL, Kechagia Z, Beedle AEM, Elosegui-Artola A, Trepat X, Farré R, Betz T, Almendros I, Roca-Cusachs P. The force loading rate drives cell mechanosensing through both reinforcement and cytoskeletal softening. Nat Commun 2021; 12:4229. [PMID: 34244477 PMCID: PMC8270983 DOI: 10.1038/s41467-021-24383-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/15/2021] [Indexed: 01/08/2023] Open
Abstract
Cell response to force regulates essential processes in health and disease. However, the fundamental mechanical variables that cells sense and respond to remain unclear. Here we show that the rate of force application (loading rate) drives mechanosensing, as predicted by a molecular clutch model. By applying dynamic force regimes to cells through substrate stretching, optical tweezers, and atomic force microscopy, we find that increasing loading rates trigger talin-dependent mechanosensing, leading to adhesion growth and reinforcement, and YAP nuclear localization. However, above a given threshold the actin cytoskeleton softens, decreasing loading rates and preventing reinforcement. By stretching rat lungs in vivo, we show that a similar phenomenon may occur. Our results show that cell sensing of external forces and of passive mechanical parameters (like tissue stiffness) can be understood through the same mechanisms, driven by the properties under force of the mechanosensing molecules involved.
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Affiliation(s)
- Ion Andreu
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
| | | | - Sebastian Hurst
- Institute of Cell Biology, Center of Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Nimesh Chahare
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Universitat Politècnica de Catalunya (UPC), Campus Nord, Barcelona, Spain
| | - Xarxa Quiroga
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Universitat de Barcelona, Barcelona, Spain
| | - Anabel-Lise Le Roux
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
| | - Zanetta Kechagia
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
| | - Amy E M Beedle
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Department of Physics, King's College London, Strand, London, UK
| | - Alberto Elosegui-Artola
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Wyss Institute for Biologically Inspired Engineering, Boston, MA, USA
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain
- Universitat de Barcelona, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig de Lluís Companys, Barcelona, Spain
- CIBER en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Madrid, Spain
| | - Ramon Farré
- Universitat de Barcelona, Barcelona, Spain
- CIBER de Enfermedades Respiratorias, Madrid, Spain
- Institut d'Investigacions Biomèdiques August Pi Sunyer, Barcelona, Spain
| | - Timo Betz
- Institute of Cell Biology, Center of Molecular Biology of Inflammation (ZMBE), University of Münster, Münster, Germany
| | - Isaac Almendros
- Universitat de Barcelona, Barcelona, Spain.
- CIBER de Enfermedades Respiratorias, Madrid, Spain.
- Institut d'Investigacions Biomèdiques August Pi Sunyer, Barcelona, Spain.
| | - Pere Roca-Cusachs
- Institute for Bioengineering of Catalonia (IBEC), the Barcelona Institute of Technology (BIST), Barcelona, Spain.
- Universitat de Barcelona, Barcelona, Spain.
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21
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Bakshi S, M VV, Sarkar R, Majumdar S. Strain localization and yielding dynamics in disordered collagen networks. SOFT MATTER 2021; 17:6435-6444. [PMID: 34132288 DOI: 10.1039/d1sm00300c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Collagen is the most abundant extracellular-matrix protein found in mammals and the main structural and load-bearing element of connective tissues. Collagen networks show remarkable strain-stiffening, which tunes the mechanical functions of tissues and regulates cell behaviours. Linear and non-linear mechanics of in vitro disordered collagen networks have been widely studied using rheology for a range of self-assembly conditions in recent years. However, the correlation between the onset of macroscopic network failure and local deformations is not well understood in these systems. Here, using shear rheology and in situ high-resolution boundary imaging, we study the yielding dynamics of in vitro reconstituted networks of uncrosslinked type-I collagen. We find that in the non-linear regime, the differential shear modulus (K) of the network initially increases with applied strain and then begins to drop as the network starts to yield beyond a critical strain (yield strain). Measurement of the local velocity profile using colloidal tracer particles reveals that beyond the peak of K, strong strain-localization and slippage between the network and the rheometer plate sets in that eventually leads to a detachment. We generalize this observation for a range of collagen concentrations, applied strain ramp rates, as well as, different network architectures obtained by varying the polymerization temperature. Furthermore, using a continuum affine network model, we map out a state diagram showing the dependence of yield-stain and -stress on the microscopic network parameters. Our findings can have broad implications in tissue engineering and designing highly resilient biological scaffolds.
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Affiliation(s)
- Swarnadeep Bakshi
- Soft Condensed Matter Group, Raman Research Institute, Bengaluru 560080, India.
| | - Vaisakh V M
- Soft Condensed Matter Group, Raman Research Institute, Bengaluru 560080, India. and Department of Physics, HKUST, Clear Water Bay, Hong Kong
| | - Ritwick Sarkar
- Soft Condensed Matter Group, Raman Research Institute, Bengaluru 560080, India.
| | - Sayantan Majumdar
- Soft Condensed Matter Group, Raman Research Institute, Bengaluru 560080, India.
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22
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A hyperelastic model for simulating cells in flow. Biomech Model Mechanobiol 2020; 20:509-520. [PMID: 33219464 PMCID: PMC7979664 DOI: 10.1007/s10237-020-01397-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 10/14/2020] [Indexed: 12/24/2022]
Abstract
In the emerging field of 3D bioprinting, cell damage due to large deformations is considered a main cause for cell death and loss of functionality inside the printed construct. Those deformations, in turn, strongly depend on the mechano-elastic response of the cell to the hydrodynamic stresses experienced during printing. In this work, we present a numerical model to simulate the deformation of biological cells in arbitrary three-dimensional flows. We consider cells as an elastic continuum according to the hyperelastic Mooney-Rivlin model. We then employ force calculations on a tetrahedralized volume mesh. To calibrate our model, we perform a series of FluidFM[Formula: see text] compression experiments with REF52 cells demonstrating that all three parameters of the Mooney-Rivlin model are required for a good description of the experimental data at very large deformations up to 80%. In addition, we validate the model by comparing to previous AFM experiments on bovine endothelial cells and artificial hydrogel particles. To investigate cell deformation in flow, we incorporate our model into Lattice Boltzmann simulations via an Immersed-Boundary algorithm. In linear shear flows, our model shows excellent agreement with analytical calculations and previous simulation data.
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23
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Hubrich H, Mey IP, Brückner BR, Mühlenbrock P, Nehls S, Grabenhorst L, Oswald T, Steinem C, Janshoff A. Viscoelasticity of Native and Artificial Actin Cortices Assessed by Nanoindentation Experiments. NANO LETTERS 2020; 20:6329-6335. [PMID: 32786944 DOI: 10.1021/acs.nanolett.0c01769] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Cell cortices are responsible for the resilience and morphological dynamics of cells. Measuring their mechanical properties is impeded by contributions from other filament types, organelles, and the crowded cytoplasm. We established a versatile concept for the precise assessment of cortical viscoelasticity based on force cycle experiments paired with continuum mechanics. Apical cell membranes of confluent MDCK II cells were deposited on porous substrates and locally deformed. Force cycles could be described with a time-dependent area compressibility modulus obeying the same power law as employed for whole cells. The reduced fluidity of apical cell membranes compared to living cells could partially be restored by reactivating myosin motors. A comparison with artificial minimal actin cortices (MACs) reveals lower stiffness and higher fluidity attributed to missing cross-links in MACs.
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Affiliation(s)
- Hanna Hubrich
- Department of Chemistry, Institute of Physical Chemistry, Göttingen 37077, Germany
| | - Ingo P Mey
- Department of Chemistry, Institute of Organic and Biomolecular Chemistry, Göttingen 37077, Germany
| | - Bastian R Brückner
- Department of Chemistry, Institute of Physical Chemistry, Göttingen 37077, Germany
| | - Peter Mühlenbrock
- Department of Chemistry, Institute of Organic and Biomolecular Chemistry, Göttingen 37077, Germany
| | - Stefan Nehls
- Department of Chemistry, Institute of Physical Chemistry, Göttingen 37077, Germany
| | - Lennart Grabenhorst
- Department of Chemistry, Institute of Physical Chemistry, Göttingen 37077, Germany
| | - Tabea Oswald
- Department of Chemistry, Institute of Organic and Biomolecular Chemistry, Göttingen 37077, Germany
| | - Claudia Steinem
- Department of Chemistry, Institute of Organic and Biomolecular Chemistry, Göttingen 37077, Germany
| | - Andreas Janshoff
- Department of Chemistry, Institute of Physical Chemistry, Göttingen 37077, Germany
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24
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Cordes A, Witt H, Gallemí-Pérez A, Brückner B, Grimm F, Vache M, Oswald T, Bodenschatz J, Flormann D, Lautenschläger F, Tarantola M, Janshoff A. Prestress and Area Compressibility of Actin Cortices Determine the Viscoelastic Response of Living Cells. PHYSICAL REVIEW LETTERS 2020; 125:068101. [PMID: 32845697 DOI: 10.1103/physrevlett.125.068101] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
Shape, dynamics, and viscoelastic properties of eukaryotic cells are primarily governed by a thin, reversibly cross-linked actomyosin cortex located directly beneath the plasma membrane. We obtain time-dependent rheological responses of fibroblasts and MDCK II cells from deformation-relaxation curves using an atomic force microscope to access the dependence of cortex fluidity on prestress. We introduce a viscoelastic model that treats the cell as a composite shell and assumes that relaxation of the cortex follows a power law giving access to cortical prestress, area-compressibility modulus, and the power law exponent (fluidity). Cortex fluidity is modulated by interfering with myosin activity. We find that the power law exponent of the cell cortex decreases with increasing intrinsic prestress and area-compressibility modulus, in accordance with previous finding for isolated actin networks subject to external stress. Extrapolation to zero tension returns the theoretically predicted power law exponent for transiently cross-linked polymer networks. In contrast to the widely used Hertzian mechanics, our model provides viscoelastic parameters independent of indenter geometry and compression velocity.
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Affiliation(s)
- Andrea Cordes
- Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Hannes Witt
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Aina Gallemí-Pérez
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Bastian Brückner
- Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Florian Grimm
- Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
- Abberior GmbH, 37077 Göttingen, Germany
| | - Marian Vache
- Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Tabea Oswald
- Institute of Org. and Biomolecular Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Jonathan Bodenschatz
- Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
| | - Daniel Flormann
- Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
| | - Franziska Lautenschläger
- Leibniz Institute for New Materials, 66123 Saarbrücken, Germany
- NT faculty, Experimental Physics, Saarland University, 66123 Saarbrücken, Germany
| | - Marco Tarantola
- Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany
| | - Andreas Janshoff
- Institute of Physical Chemistry, Georg-August-Universität Göttingen, 37077 Göttingen, Germany
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25
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Hughes MDG, Cussons S, Mahmoudi N, Brockwell DJ, Dougan L. Single molecule protein stabilisation translates to macromolecular mechanics of a protein network. SOFT MATTER 2020; 16:6389-6399. [PMID: 32578583 DOI: 10.1039/c9sm02484k] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Folded globular proteins are attractive building blocks for biopolymer-based materials, as their mechanically resistant structures carry out diverse biological functionality. While much is now understood about the mechanical response of single folded proteins, a major challenge is to understand and predictably control how single protein mechanics translates to the collective response of a network of connected folded proteins. Here, by utilising the binding of maltose to hydrogels constructed from photo-chemically cross-linked maltose binding protein (MBP), we investigate the effects of protein stabilisation at the molecular level on the macroscopic mechanical and structural properties of a protein-based hydrogel. Rheological measurements show an enhancement in the mechanical strength and energy dissipation of MBP hydrogels in the presence of maltose. Circular dichroism spectroscopy and differential scanning calorimetry measurements show that MBP remains both folded and functional in situ. By coupling these mechanical measurements with mesoscopic structural information obtained by small angle scattering, we propose an occupation model in which higher proportions of stabilised, ligand occupied, protein building blocks translate their increased stability to the macroscopic properties of the hydrogel network. This provides powerful opportunities to exploit environmentally responsive folded protein-based biomaterials for many broad applications.
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Affiliation(s)
- Matt D G Hughes
- School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, UK.
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26
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Gong T, Hu Q, Nie X, Liu T, Wang H. Periodic Dynamic Regulation of MSCs Differentiation on Redox-Sensitive Elastic Switched Substrates. ACS APPLIED BIO MATERIALS 2020; 3:3612-3620. [DOI: 10.1021/acsabm.0c00245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Tao Gong
- College of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, P. R. China
| | - Qinghua Hu
- College of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, P. R. China
| | - Xiaobo Nie
- College of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, P. R. China
| | - Tao Liu
- Medical College of Acu-Moxi and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou 510006, P. R. China
| | - Hongqing Wang
- College of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, P. R. China
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27
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Oscillating shear stress mediates mesenchymal transdifferentiation of EPCs by the Kir2.1 channel. Heart Vessels 2020; 35:1473-1482. [PMID: 32449050 DOI: 10.1007/s00380-020-01625-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 05/15/2020] [Indexed: 12/16/2022]
Abstract
Although endothelial progenitor cells (EPCs) are considered to be an essential source of vascular endothelial repair, their bidirectional differentiation determines that they play a double-edged role in the restoration of endothelial injury. In this research, we investigated the effect of Kir2.1 ion channel on the transdifferentiation of endothelial progenitor cells (EPCs) under the oscillating shear stress (OSS) and the molecular mechanisms underlying the pathological vascular remodeling. EPCs were treated with OSS (± 3.5 dynes/cm2, 1 Hz) simulated with the parallel flow chamber system. The results have shown that OSS promoted the expression of α-SMA and SM22, markers of mesenchymal cells on EPCs. Moreover, OSS also increased expression of Kir2.1 in EPCs. The down-regulation of Kir2.1 reduced OSS-induced EPC mesenchymal transdifferentiation. The overexpression of Kir2.1 suppressed the angiogenic abilities of EPCs in vitro. In parallel, the overexpression of Kir2.1 on EPCs thickened the carotid tunica intima in rat carotid artery balloon injured model in vivo. Taken together, those data indicated that the OSS could facilitate the transdifferentiation of EPCs by increasing Kir2.1 expression. This study provides a novel insight into the pathogenesis of cardiovascular diseases and gives evidence for Kir2.1 as a potential therapeutic target.
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28
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Wu H, Shen Y, Wang D, Herrmann H, Goldman RD, Weitz DA. Effect of Divalent Cations on the Structure and Mechanics of Vimentin Intermediate Filaments. Biophys J 2020; 119:55-64. [PMID: 32521238 DOI: 10.1016/j.bpj.2020.05.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 05/11/2020] [Accepted: 05/13/2020] [Indexed: 12/30/2022] Open
Abstract
Divalent cations behave as effective cross-linkers of intermediate filaments (IFs) such as vimentin IF (VIF). These interactions have been mostly attributed to their multivalency. However, ion-protein interactions often depend on the ion species, and these effects have not been widely studied in IFs. Here, we investigate the effects of two biologically important divalent cations, Zn2+ and Ca2+, on VIF network structure and mechanics in vitro. We find that the network structure is unperturbed at micromolar Zn2+ concentrations, but strong bundle formation is observed at a concentration of 100 μM. Microrheological measurements show that network stiffness increases with cation concentration. However, bundling of filaments softens the network. This trend also holds for VIF networks formed in the presence of Ca2+, but remarkably, a concentration of Ca2+ that is two orders higher is needed to achieve the same effect as with Zn2+, which suggests the importance of salt-protein interactions as described by the Hofmeister effect. Furthermore, we find evidence of competitive binding between the two divalent ion species. Hence, specific interactions between VIFs and divalent cations are likely to be an important mechanism by which cells can control their cytoplasmic mechanics.
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Affiliation(s)
- Huayin Wu
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts
| | - Yinan Shen
- Department of Physics, Harvard University, Cambridge, Massachusetts
| | - Dianzhuo Wang
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois
| | - Harald Herrmann
- Division of Cell Biology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Institute of Neuropathology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Robert D Goldman
- Department of Cell and Developmental Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - David A Weitz
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts; Department of Physics, Harvard University, Cambridge, Massachusetts.
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29
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de Sousa JS, Freire RS, Sousa FD, Radmacher M, Silva AFB, Ramos MV, Monteiro-Moreira ACO, Mesquita FP, Moraes MEA, Montenegro RC, Oliveira CLN. Double power-law viscoelastic relaxation of living cells encodes motility trends. Sci Rep 2020; 10:4749. [PMID: 32179816 PMCID: PMC7075927 DOI: 10.1038/s41598-020-61631-w] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 02/26/2020] [Indexed: 02/08/2023] Open
Abstract
Living cells are constantly exchanging momentum with their surroundings. So far, there is no consensus regarding how cells respond to such external stimuli, although it reveals much about their internal structures, motility as well as the emergence of disorders. Here, we report that twelve cell lines, ranging from healthy fibroblasts to cancer cells, hold a ubiquitous double power-law viscoelastic relaxation compatible with the fractional Kelvin-Voigt viscoelastic model. Atomic Force Microscopy measurements in time domain were employed to determine the mechanical parameters, namely, the fast and slow relaxation exponents, the crossover timescale between power law regimes, and the cell stiffness. These cell-dependent quantities show strong correlation with their collective migration and invasiveness properties. Beyond that, the crossover timescale sets the fastest timescale for cells to perform their biological functions.
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Affiliation(s)
- J S de Sousa
- Departamento de Física, Universidade Federal do Ceará, 60455-970, Fortaleza, Ceará, Brazil.
| | - R S Freire
- Central Analítica, Universidade Federal do Ceará, 60455-970, Fortaleza, Ceará, Brazil
| | - F D Sousa
- Departamento de Física, Universidade Federal do Ceará, 60455-970, Fortaleza, Ceará, Brazil
| | - M Radmacher
- Institute of Biophysics, University of Bremen, Otto-Hahn Allee 1, 28359, Bremen, Germany
| | - A F B Silva
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, 60440-554, Fortaleza, Ceará, Brazil
| | - M V Ramos
- Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, 60440-554, Fortaleza, Ceará, Brazil
| | - A C O Monteiro-Moreira
- Centro de Biologia Experimental, Universidade de Fortaleza, 60811-905, Fortaleza, Ceará, Brazil
| | - F P Mesquita
- Núcleo de Pesquisa e Desenvolvimento de Medicamentos, Universidade Federal do Ceará, 60430-275, Fortaleza, Ceará, Brazil
| | - M E A Moraes
- Núcleo de Pesquisa e Desenvolvimento de Medicamentos, Universidade Federal do Ceará, 60430-275, Fortaleza, Ceará, Brazil
| | - R C Montenegro
- Núcleo de Pesquisa e Desenvolvimento de Medicamentos, Universidade Federal do Ceará, 60430-275, Fortaleza, Ceará, Brazil
| | - C L N Oliveira
- Departamento de Física, Universidade Federal do Ceará, 60455-970, Fortaleza, Ceará, Brazil
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