Theoretical estimates of mechanical properties of the endothelial cell cytoskeleton

Satcher, Robert L.; Dewey, C. Forbes

doi:10.1016/s0006-3495(96)79206-8

Cited by 242 publications

(184 citation statements)

References 38 publications

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“…(1) as being the stiffness at the glass transition, and the parameter F 0 as being the frequency at which elements attempt to escape their energy wells. If so, then G 0 represents an upper limit of stiffness and might correspond to the stiffness defined by the purely elastic cytoskeletal model of Satcher and Dewey [25].…”

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confidence: 99%

Scaling the Microrheology of Living Cells

et al. 2001

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We report a scaling law that governs both the elastic and frictional properties of a wide variety of living cell types, over a wide range of time scales and under a variety of biological interventions. This scaling identifies these cells as soft glassy materials existing close to a glass transition, and implies that cytoskeletal proteins may regulate cell mechanical properties mainly by modulating the effective noise temperature of the matrix. The practical implications are that the effective noise temperature is an easily quantified measure of the ability of the cytoskeleton to deform, flow, and reorganize.

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confidence: 99%

Scaling the Microrheology of Living Cells

et al. 2001

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“…Because of this large aspect ratio, actin filaments form semidilute solutions at extremely low volume fractions w ϳ ͑d͞l p ͒ 2 , with an elastic modulus orders of magnitude larger than that of flexible polymers at the same volume fraction. A theoretical understanding of this elasticity is still controversial; very different results are predicted using effective medium models [6], models based on mechanical networks [7,8], networks of semiflexible molecules with effectively permanent cross-links [9], and models which consider the unique properties of networks, at different concentrations, of semiflexible polymers [6,[10][11][12][13]. Experimental measures of the modulus also suffer from wide variations, with reported values of the frequency dependent elastic modulus, G 0 ͑v͒, varying by as much as 2 orders of magnitude for apparently identical samples [14].…”

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confidence: 99%

Scaling of the Microrheology of Semidilute F-Actin Solutions

1999

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The viscoelasticity of actin networks is probed over an extended range of frequencies using microrheology techniques, where the thermal motion of small beads in the network is measured using diffusing-wave spectroscopy. Despite large sample-to-sample variations, the data exhibit an unexpected scaling behavior and can all be collapsed onto a single master curve, indicative of a surprising universality in the elastic properties. The scaled data provide a precise measure of the average behavior of the actin networks and indicate that at high frequencies v, the shear modulus, increases as v 3͞4 . [ S0031-9007(99) PACS numbers: 87.19.Tt, 61.25.Hq, 83.10.Nn, 83.50.Fc Eukaryotic cells owe their mechanical strength mainly to the cytoskeleton, an intricate network of filamentous proteins such as tubulin, vimentin, spectrin, and actin [1]. Filamentous or F-actin, the most abundant of these cytoskeletal proteins, forms by the polymerization of actin monomers in the presence of K 1 or Mg 21 , resulting in a semiflexible polymer that can be many microns long. Its persistence length, l p , has been measured to be about 10 20 mm [2-4], about 3 orders of magnitude larger than the filament diameter, d7 nm [5]. Because of this large aspect ratio, actin filaments form semidilute solutions at extremely low volume fractions w ϳ ͑d͞l p ͒ 2 , with an elastic modulus orders of magnitude larger than that of flexible polymers at the same volume fraction. A theoretical understanding of this elasticity is still controversial; very different results are predicted using effective medium models [6], models based on mechanical networks [7,8], networks of semiflexible molecules with effectively permanent cross-links [9], and models which consider the unique properties of networks, at different concentrations, of semiflexible polymers [6,[10][11][12][13]. Experimental measures of the modulus also suffer from wide variations, with reported values of the frequency dependent elastic modulus, G 0 ͑v͒, varying by as much as 2 orders of magnitude for apparently identical samples [14]. While the origin of this variation is not fully resolved, it is likely a combined effect caused by the variation in the filament length distribution and by the presence of small quantities of proteins which can act as chemical cross-links, leading to dramatic, but random, changes in the modulus. A definitive test of the proposed theoretical models requires a highly purified sample with carefully controlled filament length distribution [15]. However, it is perhaps even more crucial to develop a better understanding of the behavior of the actin networks more typically produced, both to better comprehend their properties and to determine the origin of the variability.One feature of the elastic response of actin networks that should transcend the difficulty in obtaining reproducible shear moduli is the behavior at high frequencies.When the wavelength of elastic excitation is shorter than the average spacing between entanglements, the modulus should be sensitive only to p...

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“…However, SFs are not attached to the nucleus upon initial exposure to shear stress [4,5,14,18,24,39,54,57,70]. Nevertheless, mechanical linkage between the apical surface and the nucleus exists through the effective elastic constant used for the cytoplasm.…”

Section: Geometric Modelmentioning

confidence: 99%

“…Moreover, several models of the cytoskeleton have been constructed to investigate the hypothesis that this interconnected filamentous structure can act as a mechano-signal transmitter [44][45][46][47][48][49][50][51][52][53][54][55][56]. Shafrir & [46] proposed a two-dimensional model of the cytoskeleton as a random network of rigid rods representing the actin laments and linear Hookean springs representing the actin cross-linkers.…”

Section: Introductionmentioning

confidence: 99%

Shear-induced force transmission in a multicomponent, multicell model of the endothelium

Dabagh

Jalali

Butler

et al. 2014

J. R. Soc. Interface.

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Haemodynamic forces applied at the apical surface of vascular endothelial cells (ECs) provide the mechanical signals at intracellular organelles and through the inter-connected cellular network. The objective of this study is to quantify the intracellular and intercellular stresses in a confluent vascular EC monolayer. A novel three-dimensional, multiscale and multicomponent model of focally adhered ECs is developed to account for the role of potential mechanosensors (glycocalyx layer, actin cortical layer, nucleus, cytoskeleton, focal adhesions (FAs) and adherens junctions (ADJs)) in mechanotransmission and EC deformation. The overriding issue addressed is the stress amplification in these regions, which may play a role in subcellular localization of mechanotransmission. The model predicts that the stresses are amplified 250-600-fold over apical values at ADJs and 175-200-fold at FAs for ECs exposed to a mean shear stress of 10 dyne cm 22 . Estimates of forces per molecule in the cell attachment points to the external cellular matrix and cell-cell adhesion points are of the order of 8 pN at FAs and as high as 3 pN at ADJs, suggesting that direct force-induced mechanotransmission by single molecules is possible in both. The maximum deformation of an EC in the monolayer is calculated as 400 nm in response to a mean shear stress of 1 Pa applied over the EC surface which is in accord with measurements. The model also predicts that the magnitude of the cell-cell junction inclination angle is independent of the cytoskeleton and glycocalyx. The inclination angle of the cell-cell junction is calculated to be 6.68 in an EC monolayer, which is somewhat below the measured value (9.98) reported previously for ECs subjected to 1.6 Pa shear stress for 30 min. The present model is able, for the first time, to cross the boundaries between different length scales in order to provide a global view of potential locations of mechanotransmission.

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Theoretical estimates of mechanical properties of the endothelial cell cytoskeleton

Cited by 242 publications

References 38 publications

Scaling the Microrheology of Living Cells

Scaling the Microrheology of Living Cells

Scaling of the Microrheology of Semidilute F-Actin Solutions

Shear-induced force transmission in a multicomponent, multicell model of the endothelium

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