Mechanical mismatch between Ras transformed and untransformed epithelial cells

ABSTRACTThe organization of the actin cytoskeleton plays a key role in regulating cell mechanics. It is fundamentally altered during transformation, affecting how cells interact with their environment. We investigated mechanical properties of cells expressing constitutively active, oncogenic Ras (RasV12) in adherent and suspended states. To do this, we utilized atomic force microscopy and a microfluidic optical stretcher. We found that adherent cells stiffen and suspended cells soften with the expression of constitutively active Ras. The effect on adherent cells was reversed when contractility was inhibited with the ROCK inhibitor Y-27632, resulting in softer RasV12 cells. Our findings suggest that increased ROCK activity as a result of Ras has opposite effects on suspended and adhered cells. Our results also establish the importance of the activation of ROCK by Ras and its effect on cell mechanics.

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Nanomechanical properties of enucleated cells: contribution of the nucleus to the passive cell mechanics

Journal of Nanobiotechnology ◽

10.1186/s12951-020-00696-1 ◽

2020 ◽

Vol 18 (1) ◽

Cited By ~ 1

Author(s):

Yuri M. Efremov ◽

Svetlana L. Kotova ◽

Anastasia A. Akovantseva ◽

Peter S. Timashev

Keyword(s):

Mechanical Properties ◽

Cell Mechanics ◽

Normal Cells ◽

Force Microscopy ◽

Nanomechanical Properties ◽

Atomic Force ◽

Fibrosarcoma Cells ◽

Actomyosin Cytoskeleton ◽

Small Deformations

Abstract Background The nucleus, besides its functions in the gene maintenance and regulation, plays a significant role in the cell mechanosensitivity and mechanotransduction. It is the largest cellular organelle that is often considered as the stiffest cell part as well. Interestingly, the previous studies have revealed that the nucleus might be dispensable for some of the cell properties, like polarization and 1D and 2D migration. Here, we studied how the nanomechanical properties of cells, as measured using nanomechanical mapping by atomic force microscopy (AFM), were affected by the removal of the nucleus. Methods The mass enucleation procedure was employed to obtain cytoplasts (enucleated cells) and nucleoplasts (nuclei surrounded by plasma membrane) of two cell lines, REF52 fibroblasts and HT1080 fibrosarcoma cells. High-resolution viscoelastic mapping by AFM was performed to compare the mechanical properties of normal cells, cytoplasts, and nucleoplast. The absence or presence of the nucleus was confirmed with fluorescence microscopy, and the actin cytoskeleton structure was assessed with confocal microscopy. Results Surprisingly, we did not find the softening of cytoplasts relative to normal cells, and even some degree of stiffening was discovered. Nucleoplasts, as well as the nuclei isolated from cells using a detergent, were substantially softer than both the cytoplasts and normal cells. Conclusions The cell can maintain its mechanical properties without the nucleus. Together, the obtained data indicate the dominating role of the actomyosin cytoskeleton over the nucleus in the cell mechanics at small deformations inflicted by AFM.

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Quantitative mechanical analysis of indentations on layered, soft elastic materials

Soft Matter ◽

10.1039/c8sm02121j ◽

2019 ◽

Vol 15 (8) ◽

pp. 1776-1784 ◽

Cited By ~ 7

Author(s):

Bryant L. Doss ◽

Kiarash Rahmani Eliato ◽

Keng-hui Lin ◽

Robert Ros

Keyword(s):

Atomic Force Microscopy ◽

Elastic Modulus ◽

Cell Mechanics ◽

Biological Samples ◽

Mechanical Analysis ◽

Elastic Materials ◽

Mechanical Heterogeneity ◽

Popular Method ◽

Force Microscopy ◽

Atomic Force

Atomic force microscopy (AFM) is becoming an increasingly popular method for studying cell mechanics, however the existing analysis tools for determining the elastic modulus from indentation experiments are unable to quantitatively account for mechanical heterogeneity commonly found in biological samples.

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Looking at cell mechanics with atomic force microscopy: Experiment and theory

Microscopy Research and Technique ◽

10.1002/jemt.22419 ◽

2014 ◽

Vol 77 (11) ◽

pp. 947-958 ◽

Cited By ~ 19

Author(s):

Rafael Benitez ◽

José. L. Toca-herrera

Keyword(s):

Atomic Force Microscopy ◽

Cell Mechanics ◽

Force Microscopy ◽

Atomic Force ◽

Atomic Force Microscopy Experiment

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Investigating cell mechanics with atomic force microscopy

Journal of The Royal Society Interface ◽

10.1098/rsif.2014.0970 ◽

2015 ◽

Vol 12 (104) ◽

pp. 20140970 ◽

Cited By ~ 177

Author(s):

Kristina Haase ◽

Andrew E. Pelling

Keyword(s):

Atomic Force Microscopy ◽

Cell Mechanics ◽

Normal Cell ◽

Mechanical Characterization ◽

Nonlinear Models ◽

Single Cells ◽

Mechanistic Models ◽

Force Microscopy ◽

Atomic Force ◽

Inelastic Responses

Transmission of mechanical force is crucial for normal cell development and functioning. However, the process of mechanotransduction cannot be studied in isolation from cell mechanics. Thus, in order to understand how cells ‘feel’, we must first understand how they deform and recover from physical perturbations. Owing to its versatility, atomic force microscopy (AFM) has become a popular tool to study intrinsic cellular mechanical properties. Used to directly manipulate and examine whole and subcellular reactions, AFM allows for top-down and reconstitutive approaches to mechanical characterization. These studies show that the responses of cells and their components are complex, and largely depend on the magnitude and time scale of loading. In this review, we generally describe the mechanotransductive process through discussion of well-known mechanosensors. We then focus on discussion of recent examples where AFM is used to specifically probe the elastic and inelastic responses of single cells undergoing deformation. We present a brief overview of classical and current models often used to characterize observed cellular phenomena in response to force. Both simple mechanistic models and complex nonlinear models have been used to describe the observed cellular behaviours, however a unifying description of cell mechanics has not yet been resolved.

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