1
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Singh RK, Burov S. Universal to nonuniversal transition of the statistics of rare events during the spread of random walks. Phys Rev E 2023; 108:L052102. [PMID: 38115504 DOI: 10.1103/physreve.108.l052102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 09/11/2023] [Indexed: 12/21/2023]
Abstract
Through numerous experiments that analyzed rare event statistics in heterogeneous media, it was discovered that in many cases the probability density function for particle position, P(X,t), exhibits a slower decay rate than the Gaussian function. Typically, the decay behavior is exponential, referred to as Laplace tails. However, many systems exhibit an even slower decay rate, such as power-law, log-normal, or stretched exponential. In this study, we utilize the continuous-time random walk method to investigate the rare events in particle hopping dynamics and find that the properties of the hop size distribution induce a critical transition between the Laplace universality of rare events and a more specific, slower decay of P(X,t). Specifically, when the hop size distribution decays slower than exponential, such as e^{-|x|^{β}} (β>1), the Laplace universality no longer applies, and the decay is specific, influenced by a few large events, rather than by the accumulation of many smaller events that give rise to Laplace tails.
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Affiliation(s)
- R K Singh
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Stanislav Burov
- Department of Physics, Bar-Ilan University, Ramat-Gan 5290002, Israel
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2
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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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3
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Shi Y, Sivarajan S, Crocker JC, Reich DH. Measuring Cytoskeletal Mechanical Fluctuations and Rheology with Active Micropost Arrays. Curr Protoc 2022; 2:e433. [PMID: 35612274 PMCID: PMC9321978 DOI: 10.1002/cpz1.433] [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] [Indexed: 11/07/2022]
Abstract
The dynamics of the cellular actomyosin cytoskeleton are crucial to many aspects of cellular function. Here, we describe techniques that employ active micropost array detectors (AMPADs) to measure cytoskeletal rheology and mechanical force fluctuations. The AMPADS are arrays of flexible poly(dimethylsiloxane) (PDMS) microposts with magnetic nanowires embedded in a subset of microposts to enable actuation of those posts via an externally applied magnetic field. Techniques are described to track the magnetic microposts' motion with nanometer precision at up to 100 video frames per second to measure the local cellular rheology at well-defined positions. Application of these high-precision tracking techniques to the full array of microposts in contact with a cell also enables mapping of the cytoskeletal mechanical fluctuation dynamics with high spatial and temporal resolution. This article describes (1) the fabrication of magnetic micropost arrays, (2) measurement protocols for both local rheology and cytoskeletal force fluctuation mapping, and (3) special-purpose software routines to reduce and analyze these data. © 2022 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Fabrication of magnetic micropost arrays Basic Protocol 2: Data acquisition for cellular force fluctuations on non-magnetic micropost arrays Basic Protocol 3: Data acquisition for local cellular rheology measurements with magnetic microposts Basic Protocol 4: Data reduction: determining microposts' motion Basic Protocol 5: Data analysis: determining local rheology from magnetic microposts Basic Protocol 6: Data analysis for force fluctuation measurements Support Protocol 1: Fabrication of magnetic Ni nanowires by electrodeposition Support Protocol 2: Configuring Streampix for magnetic rheology measurements.
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Affiliation(s)
- Yu Shi
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland.,Current address: Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina
| | - Shankar Sivarajan
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland
| | - John C Crocker
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Daniel H Reich
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland
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4
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A generalized Flory-Stockmayer kinetic theory of connectivity percolation and rigidity percolation of cytoskeletal networks. PLoS Comput Biol 2022; 18:e1010105. [PMID: 35533192 PMCID: PMC9119625 DOI: 10.1371/journal.pcbi.1010105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 05/19/2022] [Accepted: 04/14/2022] [Indexed: 01/07/2023] Open
Abstract
Actin networks are essential for living cells to move, reproduce, and sense their environments. The dynamic and rheological behavior of actin networks is modulated by actin-binding proteins such as α-actinin, Arp2/3, and myosin. There is experimental evidence that actin-binding proteins modulate the cooperation of myosin motors by connecting the actin network. In this work, we present an analytical mean field model, using the Flory-Stockmayer theory of gelation, to understand how different actin-binding proteins change the connectivity of the actin filaments as the networks are formed. We follow the kinetics of the networks and estimate the concentrations of actin-binding proteins that are needed to reach connectivity percolation as well as to reach rigidity percolation. We find that Arp2/3 increases the actomyosin connectivity in the network in a non-monotonic way. We also describe how changing the connectivity of actomyosin networks modulates the ability of motors to exert forces, leading to three possible phases of the networks with distinctive dynamical characteristics: a sol phase, a gel phase, and an active phase. Thus, changes in the concentration and activity of actin-binding proteins in cells lead to a phase transition of the actin network, allowing the cells to perform active contraction and change their rheological properties. The actin cytoskeleton is a complex dynamic system, regulated by multiple proteins that bind to actin filaments. Some actin-binding proteins are crosslinkers, which can bind pairs of actin filaments, forming actin networks. Actin crosslinkers can be passive linkers, providing only structural integrity, or can be active linkers such as myosin motors, which exert forces on the network. Experiments have shown that crosslinked actin networks can behave viscously when the number of passive crosslinkers is low, but become elastic, when there are many crosslinkers. Motors can only lead to contraction of the network when there is an intermediate concentration of passive crosslinkers. The behavior of networks in the cell depends on the concentration and activity of several distinct crosslinkers, which have different binding sites, geometries, affinities, and concentrations. In this work we propose a simple analytical model based on chemical kinetics and the Flory-Stockmayer theory that gives us insight into how different crosslinkers interact with the actin filaments so as to give rise to the emergent mechanical behavior. This theory also allows us to compute analytically several crucial aspects of the development of the mechanical properties during network assembly.
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5
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Barreto YB, Alencar AM. Random-walk model of the sodium-glucose transporter SGLT2 with stochastic steps and inhibition. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:184004. [PMID: 35090150 DOI: 10.1088/1361-648x/ac4fea] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/28/2022] [Indexed: 06/14/2023]
Abstract
Random-walk models are frequently used to model distinct natural phenomena such as diffusion processes, stock-market fluctuations, and biological systems. Here, we present a random-walk model to describe the dynamics of glucose uptake by the sodium-glucose transporter of type 2, SGLT2. Our starting point is the canonical alternating-access model, which suggests the existence of six states for the transport cycle. We propose the inclusion of two new states to this canonical model. The first state is added to implement the recent discovery that the Na+ion can exit before the sugar is released into the proximal tubule epithelial cells. The resulting model is a seven-state mechanism with stochastic steps. Then we determined the transition probabilities between these seven states and used them to write a set of master equations to describe the time evolution of the system. We showed that our model converges to the expected equilibrium configuration and that the binding of Na+and glucose to SGLT2 in the inward-facing conformation must be necessarily unordered. After that, we added another state to implement inhibition in the model. Our results reproduce the experimental dependence of glucose uptake on the inhibitor concentration and they reveal that the inhibitors act by decreasing the number of available SGLT2s, which increases the chances of glucose escaping reabsorption.
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Affiliation(s)
- Yan B Barreto
- Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, São Paulo, Brazil
| | - Adriano M Alencar
- Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, São Paulo, Brazil
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6
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Shi Y, Sivarajan S, Xiang KM, Kostecki GM, Tung L, Crocker JC, Reich DH. Pervasive cytoquakes in the actomyosin cortex across cell types and substrate stiffness. Integr Biol (Camb) 2021; 13:246-257. [PMID: 34875067 DOI: 10.1093/intbio/zyab017] [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: 04/05/2021] [Revised: 10/25/2021] [Accepted: 11/02/2021] [Indexed: 11/14/2022]
Abstract
The actomyosin cytoskeleton enables cells to resist deformation, crawl, change their shape and sense their surroundings. Despite decades of study, how its molecular constituents can assemble together to form a network with the observed mechanics of cells remains poorly understood. Recently, it has been shown that the actomyosin cortex of quiescent cells can undergo frequent, abrupt reconfigurations and displacements, called cytoquakes. Notably, such fluctuations are not predicted by current physical models of actomyosin networks, and their prevalence across cell types and mechanical environments has not previously been studied. Using micropost array detectors, we have performed high-resolution measurements of the dynamic mechanical fluctuations of cells' actomyosin cortex and stress fiber networks. This reveals cortical dynamics dominated by cytoquakes-intermittent events with a fat-tailed distribution of displacements, sometimes spanning microposts separated by 4 μm, in all cell types studied. These included 3T3 fibroblasts, where cytoquakes persisted over substrate stiffnesses spanning the tissue-relevant range of 4.3 kPa-17 kPa, and primary neonatal rat cardiac fibroblasts and myofibroblasts, human embryonic kidney cells and human bone osteosarcoma epithelial (U2OS) cells, where cytoquakes were observed on substrates in the same stiffness range. Overall, these findings suggest that the cortex self-organizes into a marginally stable mechanical state whose physics may contribute to cell mechanical properties, active behavior and mechanosensing.
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Affiliation(s)
- Yu Shi
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shankar Sivarajan
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Katherine M Xiang
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Geran M Kostecki
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - Leslie Tung
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD 21205, USA
| | - John C Crocker
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel H Reich
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
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7
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Abstract
The eukaryotic cell's cytoskeleton is a prototypical example of an active material: objects embedded within it are driven by molecular motors acting on the cytoskeleton, leading to anomalous diffusive behavior. Experiments tracking the behavior of cell-attached objects have observed anomalous diffusion with a distribution of displacements that is non-Gaussian, with heavy tails. This has been attributed to "cytoquakes" or other spatially extended collective effects. We show, using simulations and analytical theory, that a simple continuum active gel model driven by fluctuating force dipoles naturally creates heavy power-law tails in cytoskeletal displacements. We predict that this power law exponent should depend on the geometry and dimensionality of where force dipoles are distributed through the cell; we find qualitatively different results for force dipoles in a 3D cytoskeleton and a quasi-two-dimensional cortex. We then discuss potential applications of this model both in cells and in synthetic active gels.
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Affiliation(s)
- Daniel W Swartz
- Department of Physics and Astronomy, Johns Hopkins University, USA
- Department of Physics, Massachusetts Institute of Technology, USA
| | - Brian A Camley
- Department of Physics and Astronomy, Johns Hopkins University, USA
- Department of Biophysics, Johns Hopkins University, USA
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8
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Li C, Liman J, Eliaz Y, Cheung MS. Forecasting Avalanches in Branched Actomyosin Networks with Network Science and Machine Learning. J Phys Chem B 2021; 125:11591-11605. [PMID: 34664964 DOI: 10.1021/acs.jpcb.1c04792] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We explored the dynamic and structural effects of actin-related proteins 2/3 (Arp2/3) on actomyosin networks using mechanochemical simulations of active matter networks. On the nanoscale, the Arp2/3 complex alters the topology of actomyosin by nucleating a daughter filament at an angle with respect to a mother filament. At a subcellular scale, they orchestrate the formation of a branched actomyosin network. Using a coarse-grained approach, we sought to understand how an actomyosin network temporally and spatially reorganizes itself by varying the concentration of the Arp2/3 complexes. Driven by motor dynamics, the network stalls at a high concentration of Arp2/3 and contracts at a low Arp2/3 concentration. At an intermediate Arp2/3 concentration, however, the actomyosin network is formed by loosely connected clusters that may collapse suddenly when driven by motors. This physical phenomenon is called an "avalanche" largely due to the marginal instability inherent to the morphology of a branched actomyosin network when the Arp2/3 complex is present. While embracing the data science approaches, we unveiled the higher-order patterns in the branched actomyosin networks and discovered a sudden change in the "social" network topology of actomyosin, which is a new type of avalanche in addition to the two types of avalanches associated with a sudden change in the size or shape of the whole actomyosin network, as shown in a previous investigation. Our new finding promotes the importance of using network theory and machine learning models to forecast avalanches in actomyosin networks. The mechanisms of the Arp2/3 complexes in shaping the architecture of branched actomyosin networks obtained in this paper will help us better understand the emergent reorganization of the topology in dense actomyosin networks that are difficult to detect in experiments.
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Affiliation(s)
- Chengxuan Li
- Department of Physics, University of Houston, Houston, Texas 77204, United States.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - James Liman
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States.,Department of Bioengineering, Rice University, Houston, Texas 77030, United States
| | - Yossi Eliaz
- Department of Physics, University of Houston, Houston, Texas 77204, United States.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Margaret S Cheung
- Department of Physics, University of Houston, Houston, Texas 77204, United States.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States.,Department of Bioengineering, Rice University, Houston, Texas 77030, United States.,Pacific Northwest National Laboratory, Seattle, Washington 98109, United States
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9
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Floyd C, Levine H, Jarzynski C, Papoian GA. Understanding cytoskeletal avalanches using mechanical stability analysis. Proc Natl Acad Sci U S A 2021; 118:e2110239118. [PMID: 34611021 PMCID: PMC8521716 DOI: 10.1073/pnas.2110239118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2021] [Indexed: 12/28/2022] Open
Abstract
Eukaryotic cells are mechanically supported by a polymer network called the cytoskeleton, which consumes chemical energy to dynamically remodel its structure. Recent experiments in vivo have revealed that this remodeling occasionally happens through anomalously large displacements, reminiscent of earthquakes or avalanches. These cytoskeletal avalanches might indicate that the cytoskeleton's structural response to a changing cellular environment is highly sensitive, and they are therefore of significant biological interest. However, the physics underlying "cytoquakes" is poorly understood. Here, we use agent-based simulations of cytoskeletal self-organization to study fluctuations in the network's mechanical energy. We robustly observe non-Gaussian statistics and asymmetrically large rates of energy release compared to accumulation in a minimal cytoskeletal model. The large events of energy release are found to correlate with large, collective displacements of the cytoskeletal filaments. We also find that the changes in the localization of tension and the projections of the network motion onto the vibrational normal modes are asymmetrically distributed for energy release and accumulation. These results imply an avalanche-like process of slow energy storage punctuated by fast, large events of energy release involving a collective network rearrangement. We further show that mechanical instability precedes cytoquake occurrence through a machine-learning model that dynamically forecasts cytoquakes using the vibrational spectrum as input. Our results provide a connection between the cytoquake phenomenon and the network's mechanical energy and can help guide future investigations of the cytoskeleton's structural susceptibility.
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Affiliation(s)
- Carlos Floyd
- Biophysics Program, University of Maryland, College Park, MD 20742
| | - Herbert Levine
- Center for Theoretical Biological Physics, Northeastern University, Boston, MA 02115
- Department of Physics, Northeastern University, Boston, MA 02115
- Department of Bioengineering, Northeastern University, Boston, MA 02115
| | - Christopher Jarzynski
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742;
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742
- Department of Physics, University of Maryland, College Park, MD 20742
| | - Garegin A Papoian
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742;
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742
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10
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Barreto YB, Suki B, Alencar AM. Random-walk model of cotransport. Phys Rev E 2020; 102:022403. [PMID: 32942367 DOI: 10.1103/physreve.102.022403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 07/15/2020] [Indexed: 06/11/2023]
Abstract
We present a statistical mechanical model to describe the dynamics of an arbitrary cotransport system. Our starting point was the alternating access mechanism, which suggests the existence of six states for the cotransport cycle. Then we determined the 14 transition probabilities between these states, including a leak pathway, and used them to write a set of Master Equations for describing the time evolution of the system. The agreement between the asymptotic behavior of this set of equations and the result obtained from thermodynamics is a confirmation that leakage is compatible with the static head equilibrium condition and that our model has captured the essential physics of cotransport. In addition, the model correctly reproduced the transport dynamics found in the literature.
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Affiliation(s)
- Yan B Barreto
- Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, São Paulo, Brazil
| | - Béla Suki
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts 02215, USA
| | - Adriano M Alencar
- Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, São Paulo, Brazil
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11
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The role of the Arp2/3 complex in shaping the dynamics and structures of branched actomyosin networks. Proc Natl Acad Sci U S A 2020; 117:10825-10831. [PMID: 32354995 DOI: 10.1073/pnas.1922494117] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Actomyosin networks give cells the ability to move and divide. These networks contract and expand while being driven by active energy-consuming processes such as motor protein walking and actin polymerization. Actin dynamics is also regulated by actin-binding proteins, such as the actin-related protein 2/3 (Arp2/3) complex. This complex generates branched filaments, thereby changing the overall organization of the network. In this work, the spatiotemporal patterns of dynamical actin assembly accompanying the branching-induced reorganization caused by Arp2/3 were studied using a computational model (mechanochemical dynamics of active networks [MEDYAN]); this model simulates actomyosin network dynamics as a result of chemical reactions whose rates are modulated by rapid mechanical equilibration. We show that branched actomyosin networks relax significantly more slowly than do unbranched networks. Also, branched networks undergo rare convulsive movements, "avalanches," that release strain in the network. These avalanches are associated with the more heterogeneous distribution of mechanically linked filaments displayed by branched networks. These far-from-equilibrium events arising from the marginal stability of growing actomyosin networks provide a possible mechanism of the "cytoquakes" recently seen in experiments.
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12
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Shi Y, Porter CL, Crocker JC, Reich DH. Dissecting fat-tailed fluctuations in the cytoskeleton with active micropost arrays. Proc Natl Acad Sci U S A 2019; 116:13839-13846. [PMID: 31239336 PMCID: PMC6628664 DOI: 10.1073/pnas.1900963116] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of animal cells to crawl, change their shape, and respond to applied force is due to their cytoskeleton: A dynamic, cross-linked network of actin protein filaments and myosin motors. How these building blocks assemble to give rise to cells' mechanics and behavior remains poorly understood. Using active micropost array detectors containing magnetic actuators, we have characterized the mechanics and fluctuations of cells' actomyosin cortex and stress fiber network in detail. Here, we find that both structures display remarkably consistent power law viscoelastic behavior along with highly intermittent fluctuations with fat-tailed distributions of amplitudes. Notably, this motion in the cortex is dominated by occasional large, step-like displacement events, with a spatial extent of several micrometers. Overall, our findings for the cortex appear contrary to the predictions of a recent active gel model, while suggesting that different actomyosin contractile units act in a highly collective and cooperative manner. We hypothesize that cells' actomyosin components robustly self-organize into marginally stable, plastic networks that give cells' their unique biomechanical properties.
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Affiliation(s)
- Yu Shi
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218
| | - Christopher L Porter
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
| | - John C Crocker
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104
| | - Daniel H Reich
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218;
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13
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do Amaral JB, Bloise AC, França CN, Perez-Novo C, Machado-Santelli GM, Alencar AM, Pezato R. Alterations in cellular force parameters and cell projections in Nasal polyps-derived fibroblasts. Auris Nasus Larynx 2019; 47:98-104. [PMID: 31272842 DOI: 10.1016/j.anl.2019.06.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 06/07/2019] [Accepted: 06/20/2019] [Indexed: 02/03/2023]
Abstract
OBJECTIVE Chronic Rhinosinusitis with Nasal Polyps (CRSwNP) is a disease that features a mechanical dysfunction involving chronic inflammation and altered tissue remodeling. In this study, we aim to evaluate the fibroblast morphology and its cellular traction force in primary fibroblasts cell cultures obtained from both healthy individuals (n=7) and patients with CRSwNP (n=8). METHODS Using a Traction-force Microscopy we analyzed parameters of Force/Tension in fibroblasts cultures in both experimental groups. RESULTS The analysis of the Projected Area of Cell revealed that fibroblasts derived from nasal mucosa of healthy individuals have an area on average 39.24% larger than the fibroblasts obtained from the nasal polyp tissue. We also observed that the parameters directly related to the force of the cell, Max Cumulative Force and Net Contractile Moment, presented a high Force/Tension per unit of area in the fibroblasts derived from the healthy nasal mucosa (on average 41% and 52.54% higher than the fibroblasts of the nasal polyp respectively). CONCLUSION Our results demonstrate a cellular mechanism that may be associated with the mechanical dysfunction found in the Nasal Polyp tissue. The weak traction force of nasal polyp-derived fibroblast may, in lower dimensions, impact on the remodeling of nasal mucosa in CRSwNP.
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Affiliation(s)
- Jônatas Bussador do Amaral
- ENT Research Lab., Department of Otorhinolaryngology - Head and Neck Surgery, Federal University of Sao Paulo, Rua Coronel Lisboa, 958, Vila Clementino, São Paulo, SP, 04020-041, Brazil.
| | - Antonio Carlos Bloise
- Institute of Physics, University of Sao Paulo, Rua do Matão, Travessa R Número 187, Cidade Universitária, São Paulo, SP 05508-090, Brazil
| | - Carolina Nunes França
- Universidade Santo Amaro, Pós Graduação em Ciências da Saúde, Rua Enéas de Siqueira Neto, 340 Jardim das Imbuias, São Paulo, SP 04829-300, Brazil
| | - Claudina Perez-Novo
- Laboratory of Proteinchemistry, Proteomics and Epigenetic Signalling Department of Biomedical Sciences, Campus Drie Eiken, building T, first floor Universiteitsplein 1 2610 Wilrijk University of Antwerp, Belgium
| | - Gláucia Maria Machado-Santelli
- Department of Cell and Developmental Biology, Institute of Biomedical Sciences, University of Sao Paulo, Avenida Prof Lineu Prestes, 1524, dade Universitária, Sao Paulo, SP 05508-900, Brazil
| | - Adriano Mesquita Alencar
- Institute of Physics, University of Sao Paulo, Rua do Matão, Travessa R Número 187, Cidade Universitária, São Paulo, SP 05508-090, Brazil
| | - Rogério Pezato
- ENT Research Lab., Department of Otorhinolaryngology - Head and Neck Surgery, Federal University of Sao Paulo, Rua Coronel Lisboa, 958, Vila Clementino, São Paulo, SP, 04020-041, Brazil
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14
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Pezato R, Voegels RL, Pignatari S, Gregório LC, Pinto Bezerra TF, Gregorio L, Balsalobre L, Tepedino MS, Coronel N, Pinna FDR, Mendes Neto J, Oliveira P, Macoto E, Stefanini R, Figueiredo C, Haddad F, Pilan R, Bezerra Soter A, Melo NA, Candido DA, Amaral JD, Santos RDP, Van Zele T, Fujita R, Dreyfuss JL, Chamon W, Alencar AM, Perez-Novo C, Stamm AC. Nasal Polyposis: More than a Chronic Inflammatory Disorder-A Disease of Mechanical Dysfunction-The São Paulo Position. Int Arch Otorhinolaryngol 2019; 23:241-249. [PMID: 30956711 PMCID: PMC6449132 DOI: 10.1055/s-0038-1676659] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/21/2018] [Indexed: 01/02/2023] Open
Abstract
Introduction The importance of our study lies in the fact that we have demonstrated the occurrence of mechanical dysfunction within polypoid tissues, which promotes the development of polyps in the nasal cavity. Objective To change the paradigm of nasal polyposis (NP). In this new conception, the chronic nasal inflammatory process that occurs in response to allergies, to pollution, to changes in the epithelial barrier, or to other factors is merely the trigger of the development of the disease in individuals with a genetic predisposition to an abnormal tissue remodeling process, which leads to a derangement of the mechanical properties of the nasal mucosa and, consequently, allows it to grow unchecked. Data Synthesis We propose a fundamentally new approach to intervening in the pathological process of NP, addressing biomechanical properties, fluid dynamics, and the concept of surface tension. Conclusion The incorporation of biomechanical knowledge into our understanding of NP provides a new perspective to help elucidate the physiology and the pathology of nasal polyps, and new avenues for the treatment and cure of NP.
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Affiliation(s)
- Rogerio Pezato
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Shirley Pignatari
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Luiz Carlos Gregório
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Luciano Gregorio
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Leonardo Balsalobre
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Nathália Coronel
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - José Mendes Neto
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Pedro Oliveira
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Eduardo Macoto
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Renato Stefanini
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Claudia Figueiredo
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Fernanda Haddad
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | - Renata Pilan
- Department of Otolaryngology, USP, São Paulo, SP, Brazil
| | | | | | | | - Jonatas do Amaral
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Thibaut Van Zele
- Ear, Nose and Throat Department,, University of Ghent, Ghent, Belgium
| | - Reginaldo Fujita
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
| | | | - Wallace Chamon
- Department of Ophthalmology and Visual Sciences, Unifesp, São Paulo, SP, Brazil
- Department of Ophthalmology and Visual Sciences, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States
| | - Adriano Mesquita Alencar
- Laboratory of Microrheology and Molecular Physiology, Institute of Physics, USP, São Paulo, SP, Brazil
| | - Claudina Perez-Novo
- Proteinscience, Proteomics and Epigenetic Signaling, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Aldo Cassol Stamm
- Department of Otolaryngology – Head and Neck Surgery, Unifesp, São Paulo, SP, Brazil
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15
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Anghelina M, Butt O, Moldovan L, Petrache HI, Moldovan NI. Solvent isotope effect on leukocytes disintegration after large mechanical deformations. Biomed Phys Eng Express 2019. [DOI: 10.1088/2057-1976/aafd0f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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16
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Dorta MP, de Brito IV, Pereira AC, Alencar AM. Quantification of alignment of vascular smooth muscle cells. Cytometry A 2018; 93:533-539. [DOI: 10.1002/cyto.a.23355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 02/05/2018] [Accepted: 02/13/2018] [Indexed: 12/18/2022]
Affiliation(s)
- Marcel P. Dorta
- Laboratory of Microrheology and Molecular Physiology, Department of General Physics, Physics InstituteUniversity of São PauloSão Paulo Brazil
| | - Isis V. de Brito
- Laboratory of Microrheology and Molecular Physiology, Department of General Physics, Physics InstituteUniversity of São PauloSão Paulo Brazil
| | - Alexandre C. Pereira
- Laboratory of Genetics and Molecular Cardiology, Department of Cardiology, Heart Institute, Medical SchoolUniversity of São PauloSão Paulo Brazil
| | - Adriano M. Alencar
- Laboratory of Microrheology and Molecular Physiology, Department of General Physics, Physics InstituteUniversity of São PauloSão Paulo Brazil
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