Hypergravity affects Cell Traction Forces of Fibroblasts

ABSTRACTCells sense and react on changes of the mechanical properties of their environment, and likewise respond to external mechanical stress applied to them. Whether the gravitational field, as overall body force, modulates cellular behavior is however unclear. Different studies demonstrated that micro- and hypergravity influences the shape and elasticity of cells, initiate cytoskeleton reorganization, and influence cell motility. All these cellular properties are interconnected, and contribute to forces that cells apply on their surrounding microenvironment. Yet, studies that investigated changes of cell traction forces under hypergravity conditions are scarce. Here we performed hypergravity experiments on 3T3 fibroblast cells using the Large Diameter Centrifuge at the European Space and Technology Centre (ESA-ESTEC). cells were exposed to hypergravity of up to 19.5g for 16 h in both the upright and the inverted orientation with respect to the g-force vector. We observed a decrease in cellular traction forces when the gravitational field was increased up to 5.4g, followed by an increase of traction forces for higher gravity fields up to 19.5g independent of the orientation of the gravity vector. We attribute the switch in cellular response to shear-thinning at low g-forces, followed by significant rearrangement and enforcement of the cytoskeleton at high g-forces.SIGNIFICANCEThe behavior of cells critically depend on the mechanical properties of their environment. For example external stresses and strains lead to decisions in cell differentiation as well as to collective-migration in metastasis. Gravity, as a permanently acting body force, is one of those externs stresses. We demonstrate the impact of gravitational challenges on forces that cells apply to their environment. We observed a switch in cellular response with a decrease in cell traction forces for low bypgrarayiv. conditions, followed by a significant increase in cell traction forces at higher g-level. This particular cellular response reflects a switch in croskeletal organization, similar to that observed for cells in fluids where shear forces act.

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Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146783 ◽

1993 ◽

Vol 51 ◽

pp. 188-189

Author(s):

Tim Oliver ◽

Michelle Leonard ◽

Juliet Lee ◽

Akira Ishihara ◽

Ken Jacobson

Keyword(s):

Silicone Rubber ◽

Molecular Motors ◽

Video Frame ◽

Traction Forces ◽

Cell Traction Forces ◽

Latex Beads ◽

Cell Traction ◽

Local Cell ◽

Microscopic Measurement ◽

Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

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Cell Traction Forces Direct Fibronectin Matrix Assembly

Biophysical Journal ◽

10.1016/j.bpj.2008.10.009 ◽

2009 ◽

Vol 96 (2) ◽

pp. 729-738 ◽

Cited By ~ 99

Author(s):

Christopher A. Lemmon ◽

Christopher S. Chen ◽

Lewis H. Romer

Keyword(s):

Matrix Assembly ◽

Traction Forces ◽

Cell Traction Forces ◽

Fibronectin Matrix ◽

Cell Traction

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Dissipation of contractile forces: the missing piece in cell mechanics

Molecular Biology of the Cell ◽

10.1091/mbc.e16-09-0672 ◽

2017 ◽

Vol 28 (14) ◽

pp. 1825-1832 ◽

Cited By ~ 12

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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