Pre-stress of actin cortices is important for the viscoelastic response of living cells

Cordes, Andrea; Witt, Hannes; Gallemí-Pérez, Aina; Brueckner, Bastian Rouven; Grimm, Florian; Vache, Marian; Oswald, Tabea A.; Floormann, Daniel; Lautenschlaeger, Franziska; Tarantola, Marco; Janshoff, Andreas

doi:10.1101/783613

Cited by 2 publications

(19 citation statements)

References 30 publications

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“…However, we were able to partly restore fluidity by adding exogenous ATP (adenosine triphosphate) to activate myosin II. Depolymerization of actin filaments also increases fluidity of the cortex as expected from experiments with living cells. , Apical cell membranes revived with exogenous ATP reveal the same universal scaling behavior as found for living cells, confirming that the cortex is likely to be a major source of viscoelasticity measured in whole cell experiments. , …”

Section: Introductionsupporting

confidence: 70%

“…Assuming power law rheology of the thin apical cell membranes provides us with access to apparent elastic modules, prestress, and the power law exponent (fluidity). Compared to the viscoelastic properties of living cells, isolated cortices show lower area compressibility modules and lower power law exponents indicative of less transient networks . However, we were able to partly restore fluidity by adding exogenous ATP (adenosine triphosphate) to activate myosin II.…”

Section: Introductionmentioning

confidence: 75%

“…While a typical power law exponent of 0.5 is observed at low frequencies, single filament mechanics prevails at higher frequencies when cross-linkers are permanently closed . Recently, it was found that the power law coefficient depends on external and internal prestress. , …”

Section: Introductionmentioning

confidence: 99%

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Viscoelasticity of Native and Artificial Actin Cortices Assessed by Nanoindentation Experiments

Hubrich

Mey²,

Brückner

et al. 2020

Nano Lett.

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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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Section: Introductionsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 75%

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Viscoelasticity of Native and Artificial Actin Cortices Assessed by Nanoindentation Experiments

Hubrich

Mey²,

Brückner

et al. 2020

Nano Lett.

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“…The prefactor J 0 is the creep compliance of the cell and is a measure for its stiffness. That is, J 0 is proportional to the inverse of the stiffness 15 , 33 , 49 . The dimensionless parameter β characterizes the viscoelastic state of the cell.…”

Section: Methodsmentioning

confidence: 99%

“…At β = 0 the cell behaves as an ideal elastic solid following Hooke’s law, whereas at β = 1 it behaves as a Newtonian liquid. Therefore β is a measure for the fluidity of the cells 15 , 38 , 49 .…”

Section: Methodsmentioning

confidence: 99%

Cell mechanical properties of human breast carcinoma cells depend on temperature

Aermes

Hayn

Fischer

et al. 2021

Sci Rep

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The knowledge of cell mechanics is required to understand cellular processes and functions, such as the movement of cells, and the development of tissue engineering in cancer therapy. Cell mechanical properties depend on a variety of factors, such as cellular environments, and may also rely on external factors, such as the ambient temperature. The impact of temperature on cell mechanics is not clearly understood. To explore the effect of temperature on cell mechanics, we employed magnetic tweezers to apply a force of 1 nN to 4.5 µm superparamagnetic beads. The beads were coated with fibronectin and coupled to human epithelial breast cancer cells, in particular MCF-7 and MDA-MB-231 cells. Cells were measured in a temperature range between 25 and 45 °C. The creep response of both cell types followed a weak power law. At all temperatures, the MDA-MB-231 cells were pronouncedly softer compared to the MCF-7 cells, whereas their fluidity was increased. However, with increasing temperature, the cells became significantly softer and more fluid. Since mechanical properties are manifested in the cell’s cytoskeletal structure and the paramagnetic beads are coupled through cell surface receptors linked to cytoskeletal structures, such as actin and myosin filaments as well as microtubules, the cells were probed with pharmacological drugs impacting the actin filament polymerization, such as Latrunculin A, the myosin filaments, such as Blebbistatin, and the microtubules, such as Demecolcine, during the magnetic tweezer measurements in the specific temperature range. Irrespective of pharmacological interventions, the creep response of cells followed a weak power law at all temperatures. Inhibition of the actin polymerization resulted in increased softness in both cell types and decreased fluidity exclusively in MDA-MB-231 cells. Blebbistatin had an effect on the compliance of MDA-MB-231 cells at lower temperatures, which was minor on the compliance MCF-7 cells. Microtubule inhibition affected the fluidity of MCF-7 cells but did not have a significant effect on the compliance of MCF-7 and MDA-MB-231 cells. In summary, with increasing temperature, the cells became significant softer with specific differences between the investigated drugs and cell lines.

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Pre-stress of actin cortices is important for the viscoelastic response of living cells

Cited by 2 publications

References 30 publications

Viscoelasticity of Native and Artificial Actin Cortices Assessed by Nanoindentation Experiments

Viscoelasticity of Native and Artificial Actin Cortices Assessed by Nanoindentation Experiments

Cell mechanical properties of human breast carcinoma cells depend on temperature

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