scholarly journals Substrate Resistance to Traction Forces Controls Fibroblast Polarization

2020 ◽  
Author(s):  
D. Missirlis ◽  
T. Haraszti ◽  
L. Heckmann ◽  
J. P. Spatz
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Focal Adhesion ◽  
Human Fibroblasts ◽  
Traction Force ◽  
Cell Polarization ◽  
Cell Physiology ◽  
Traction Forces ◽  
Cellular Processes ◽  
Cell Mechanosensing

AbstractThe mechanics of fibronectin-rich extracellular matrix regulate cell physiology in a number of diseases, prompting efforts to elucidate cell mechanosensing mechanisms at the molecular and cellular scale. Here, the use of fibronectin-functionalized silicone elastomers that exhibit considerable frequency-dependence in viscoelastic properties unveiled the presence of two cellular processes that respond discreetly to substrate mechanical properties. Soft elastomers supported efficient focal adhesion maturation and fibroblast spreading due to an apparent stiff surface layer. However, soft elastomers did not enable cytoskeletal and fibroblast polarization; elastomers with high cross-linking and low deformability were required for polarization. The underlying reason for this behavior was the inability of soft elastomeric substrates to resist traction forces, rather than a lack of sufficient traction force generation; accordingly, mild inhibition of actomyosin contractility rescued fibroblast polarization even on the softer elastomers. Our findings help reconcile previously proposed local and global models of cell mechanosensing by demonstrating the differential dependence of substrate mechanics on distinct cellular processes.Statement of SignificanceThe mechanisms cells employ to sense and respond to the mechanical properties of their surroundings remain incompletely understood. In this study we used a commercial silicone elastomer formulation to prepare compliant, fibronectin-coated substrates and investigate the adhesion and polarization of human fibroblasts. Our results suggest the existence of at least two discrete mechanosensing processes regulated at different time and length (force) scales. Focal adhesion assembly and cell spreading were promoted by a stiff surface layer independent from bulk viscoelasticity, whereas effective cell polarization required elevated elastomer stiffness, sufficient to resist applied cell traction. The results presented here have implications on the use of elastomeric substrates as biomaterials for mechanosensing studies or clinical applications.

Study of Cellular Adhesion by Means of Micropillar Surface Topologies

2011 ◽  
Vol 409 ◽  
pp. 105-110 ◽  
Author(s):  
Francesca Boccafoschi ◽  
Marco Rasponi ◽  
Cecilia Mosca ◽  
Erica Bocchi ◽  
Simone Vesentini
Keyword(s):  
Focal Adhesion ◽  
Vascular Tissue ◽  
Focal Adhesions ◽  
Traction Force ◽  
Cellular Adhesion ◽  
Research Field ◽  
Traction Forces ◽  
Adhesion Sites ◽  
Substrate Rigidity ◽  
Open Question

It is well-known that cellular behavior can be guided by chemical signals and physical interactions at the cell-substrate interface. The patterns that cells encounter in their natural environment include nanometer-to-micrometer-sized topographies comprising extracellular matrix, proteins, and adjacent cells. Whether cells transduce substrate rigidity at the microscopic scale (for example, sensing the rigidity between adhesion sites) or the nanoscopic scale remains an open question. Here we report that micromolded elastomeric micropost arrays can decouple substrate rigidity from adhesive and surface properties. Arrays of poly (dimethylsiloxane) (PDMS) microposts from microfabricated silicon masters have been fabricated. To control substrate rigidity they present the same post heights but different surface area and spacing between posts. The main advantage of micropost arrays over other surface modification solutions (i.e. hydrogels) is that measured subcellular traction forces could be attributed directly to focal adhesions. This would allow to map traction forces to individual focal adhesions and spatially quantify subcellular distributions of focal-adhesion area, traction force and focal-adhesion stress. Moreover, different adhesion intracellular pathways could be used by the cells to differentiate toward a proliferative or a contractile cellular phenotype, for instance. This particular application is advantageous for vascular tissue engineering applications, where mimicking as close as possible the vessels dynamics should be a step forward in this research field.

scholarly journals Force-independent interactions of talin and vinculin govern integrin-mediated mechanotransduction

2019 ◽  
Author(s):  
Paul Atherton ◽  
Franziska Lausecker ◽  
Alexandre Carisey ◽  
Andrew Gilmore ◽  
David Critchley ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Critical Role ◽  
Traction Force ◽  
Full Length ◽  
Mitochondrial Targeting ◽  
Integrin Activation ◽  
Traction Forces ◽  
The Matrix ◽  
Core Components ◽  
Dynamic Link

Talin, vinculin and paxillin are core components of the dynamic link between integrins and actomyosin. Here we study the mechanisms that mediate their activation and association using a mitochondrial-targeting assay, structure-based mutants, and advanced microscopy. As expected, full-length vinculin and talin are auto-inhibited and do not interact with each other in this state. Contrary to previous models that propose a critical role for forces driving talin-vinculin association, our data show that force-independent relief of auto-inhibition is sufficient to mediate their tight interaction. Interestingly, paxillin can bind to both talin and vinculin when either is inactive. Further experiments demonstrate that adhesions containing paxillin and vinculin can form without talin following integrin activation. However, these are largely deficient in exerting traction forces to the matrix. Our observations lead to a model whereby paxillin contributes to talin and vinculin recruitment into nascent adhesions. Activation of the talin-vinculin axis subsequently leads to the engagement with the traction force-machinery and focal adhesion maturation.

scholarly journals The biochemical composition of the actomyosin network sets the magnitude of cellular traction forces

2021 ◽  
Vol 32 (18) ◽  
pp. 1737-1748
Author(s):  
Somanna Kollimada ◽  
Fabrice Senger ◽  
Timothée Vignaud ◽  
Manuel Théry ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Focal Adhesion ◽  
Biochemical Composition ◽  
Force Production ◽  
Traction Force ◽  
Traction Force Microscopy ◽  
Traction Forces ◽  
Force Microscopy ◽  
Cell Force

The endogenous content of proteins associated with force production and the resultant traction forces were quantified in the same cells using a new traction force-microscopy assay. Focal adhesion size correlated with force in stationary cells. Relative numbers of motors and cross-linkers per actin required an optimum to maximize cell force production.

scholarly journals Correlation of cellular traction forces and dissociation kinetics of adhesive protein zyxin revealed by multi-parametric live cell microscopy

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251411
Author(s):  
Lorena Sigaut ◽  
Micaela Bianchi ◽  
Catalina von Bilderling ◽  
Lía Isabel Pietrasanta
Keyword(s):  
Extracellular Matrix ◽  
Residence Time ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Traction Force ◽  
Correlation Spectroscopy ◽  
Substrate Stiffness ◽  
Dissociation Kinetics ◽  
Traction Forces ◽  
Cellular Division

Cells exert traction forces on the extracellular matrix to which they are adhered through the formation of focal adhesions. Spatial-temporal regulation of traction forces is crucial in cell adhesion, migration, cellular division, and remodeling of the extracellular matrix. By cultivating cells on polyacrylamide hydrogels of different stiffness we were able to investigate the effects of substrate stiffness on the generation of cellular traction forces by Traction Force Microscopy (TFM), and characterize the molecular dynamics of the focal adhesion protein zyxin by Fluorescence Correlation Spectroscopy (FCS) and Fluorescence Recovery After Photobleaching (FRAP). As the rigidity of the substrate increases, we observed an increment of both, cellular traction generation and zyxin residence time at the focal adhesions, while its diffusion would not be altered. Moreover, we found a positive correlation between the traction forces exerted by cells and the residence time of zyxin at the substrate elasticities studied. We found that this correlation persists at the subcellular level, even if there is no variation in substrate stiffness, revealing that focal adhesions that exert greater traction present longer residence time for zyxin, i.e., zyxin protein has less probability to dissociate from the focal adhesion.

scholarly journals Analysis of Different Complex Multilayer PACVD Coatings on Nanostructured WC-Co Cemented Carbide

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 823
Author(s):  
Danko Ćorić ◽  
Mateja Šnajdar Musa ◽  
Matija Sakoman ◽  
Željko Alar
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Base Material ◽  
Single Layer ◽  
Production Costs ◽  
Structural Defects ◽  
Cemented Carbides ◽  
Material System ◽  
Tin Coating ◽  
Ticn Coating

The development of cemented carbides nowadays is aimed at the application and sintering of ultrafine and nano-sized powders for the production of a variety of components where excellent mechanical properties and high wear resistance are required for use in high temperature and corrosive environment conditions. The most efficient way of increasing the tribological properties along with achieving high corrosion resistance is coating. Using surface processes (modification and/or coating), it is possible to form a surface layer/base material system with properties that can meet modern expectations with acceptable production costs. Three coating systems were developed on WC cemented carbides substrate with the addition of 10 wt.% Co using the plasma-assisted chemical vapor deposition (PACVD) method: single-layer TiN coating, harder multilayer gradient TiCN coating composed of TiN and TiCN layers, and the hardest multilayer TiBN coating composed of TiN and TiB2. Physical and mechanical properties of coated and uncoated samples were investigated by means of quantitative depth profile (QDP) analysis, nanoindentation, surface layer characterization (XRD analysis), and coating adhesion evaluation using the scratch test. The results confirm the possibility of obtaining nanostructured cemented carbides of homogeneous structure without structural defects such as eta phase or unbound carbon providing increase in hardness and fracture toughness. The lowest adhesion was detected for the single-layer TiN coating, while coatings with a complex architecture (TiCN, TiBN) showed improved adhesion.

High-throughput microfluidic compressibility cytometry using multi-tilted-angle surface acoustic wave

Lab on a Chip ◽  
2021 ◽  
Author(s):  
Yanqi Wu ◽  
Alastair Stewart ◽  
Peter Vee-Sin Lee
Keyword(s):  
Mechanical Properties ◽  
Acoustic Wave ◽  
Surface Acoustic Wave ◽  
High Throughput ◽  
Mechanical Measurement ◽  
Cellular Processes ◽  
Tilted Angle

Cellular mechanical properties (e.g. compressibility) are important biophysical markers in relation to cellular processes and functionality. Among the methods for cell mechanical measurement, acoustofluidic methods appear to be advantageous due...

The Effect of Cross-Linking on Nano-Mechanical Properties of Polyamide

2016 ◽  
Vol 699 ◽  
pp. 37-42 ◽  
Author(s):  
Martin Ovsik ◽  
David Manas ◽  
Miroslav Manas ◽  
Michal Stanek ◽  
Martin Reznicek
Keyword(s):  
Mechanical Properties ◽  
Surface Layer ◽  
Material Properties ◽  
Basic Material ◽  
Nanoindentation Test ◽  
Cross Linking ◽  
Indentation Hardness ◽  
Depth Sensing ◽  
Nanomechanical Properties ◽  
Radiation Crosslinking

Radiation crosslinking of polyamidu 6 (PA 6) is a well-recognized modification of improving basic material characteristics. Radiation, which penetrated through specimens and reacted with the cross-linking agent, gradually formed cross-linking (3D net), first in the surface layer and then in the total volume, which resulted in considerable changes in specimen behaviour. This research paper deals with the possible utilization of irradiated PA6. The material already contained a special cross-linking agent TAIC (5 volume %), which should enable subsequent cross-linking by ionizing β – radiation (15, 30 and 45 kGy). The effect of the irradiation on mechanical behavior of the tested PA 6 was investigated. Material properties created by β – radiation are measured by nanoindentation test using the DSI method (Depth Sensing Indentation). Hardness increased with increasing dose of irradiation at everything samples; however results of nanoindentation test shows increasing in nanomechanical properties of surface layer. The highest values of nanomechanical properties were reached radiation dose of 45 kGy, when the nanomechanical values increased by about 95%. These results indicate advantage cross-linking of the improved mechanical properties.

scholarly journals Dissipation of contractile forces: the missing piece in cell mechanics

2017 ◽  
Vol 28 (14) ◽  
pp. 1825-1832 ◽  
Author(s):  
Laetitia Kurzawa ◽  
Benoit Vianay ◽  
Fabrice Senger ◽  
Timothée Vignaud ◽  
Laurent Blanchoin ◽  
...  
Keyword(s):  
Cell Mechanics ◽  
Force Production ◽  
Traction Force ◽  
Structural Rearrangements ◽  
Force Transmission ◽  
Traction Forces ◽  
Cell Traction Forces ◽  
Cell Traction ◽  
Contractile Forces ◽  
Fiber Contraction

Mechanical forces are key regulators of cell and tissue physiology. The basic molecular mechanism of fiber contraction by the sliding of actin filament upon myosin leading to conformational change has been known for decades. The regulation of force generation at the level of the cell, however, is still far from elucidated. Indeed, the magnitude of cell traction forces on the underlying extracellular matrix in culture is almost impossible to predict or experimentally control. The considerable variability in measurements of cell-traction forces indicates that they may not be the optimal readout to properly characterize cell contractile state and that a significant part of the contractile energy is not transferred to cell anchorage but instead is involved in actin network dynamics. Here we discuss the experimental, numerical, and biological parameters that may be responsible for the variability in traction force production. We argue that limiting these sources of variability and investigating the dissipation of mechanical work that occurs with structural rearrangements and the disengagement of force transmission is key for further understanding of cell mechanics.

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