Mechanically induced deformation and strain dynamics in actin stress fibers

Abstract

It is becoming evident that physical forces in the microenvironment play a key role in regulating many important aspects of cell biology. However, although mechanical cues are known to have clear effects over the long-term (days), the short-term (seconds to minutes) cellular responses to mechanical stimuli are less well characterized. In our recent study, we exposed committed fibroblast cells to well controlled nanoscale forces while simultaneously imaging force transduction through the actin cytoskeleton. One of the earliest responses of a cell to physical force is rapid deformation of the cytoskeleton, taking place over the course of seconds. We were able to directly visualize deformation, force-propagation and strain dynamics in actin stress fibers in response to a relatively simple mechanical stimulus. Moreover, these dynamics were also dependent on myosin-driven contractility and the presence of an intact microtubule cytoskeleton. Interestingly, although stem cells are sensitive to mechanical cues, they do not display the same degree of stress fiber organization as observed in committed cells indicating the possibility of alternative sensing and mechanotransduction mechanisms.

Mechanical force induces mitochondrial fission

“…Although the force application can be precisely measured at the AFM tip, it is virtually impossible to know what fraction of the force was transduced to underlying mitochondria because the cortical actin meshwork likely buffered a large fraction. Of note, forces in the nanonewton range are typically needed to induce deformation of the actin cytoskeleton ( Hadjiantoniou et al, 2012 ).…”

Methods for Studying Endometrial Pathology and the Potential of Atomic Force Microscopy in the Research of Endometrium

“…Locating the AFM tip above the point of interest of the cell, e.g., the nucleus, allows the cell to be pressed with a well-defined nanonewton force, thus enabling observation of the mechanical response of the cytoskeleton. Such an approach enabled Hadjiantoniou et al to determine that the reaction to local force is not homogeneous in the whole cell [ 27 ]. It was confirmed that a highly localized deformation occurs far from the point of force application.…”

“…Micropipette aspiration Determination of bovine aortic endothelial cells adhesion [24] Optical tweezers Intercellular adhesion of the early embryo epithelial cells determined by cell displacement [25] Assessment of the influence of neighboring cells on the stiffness of breast cancer cells [26] Atomic force microscopy Detecting fibroblast cell inhomogeneities based on point cell pressing [27] Force mapping: Young's modulus maps e.g., of mammary gland cancer [28], primary human pulmonary artery endothelial cells [29][30][31], epithelial-like breast carcinoma cells [32] and elasticity maps e.g., of human aortic endothelial cells [33] Elasticity measurements of human umbilical vein endothelial cells, chondrocytes, fibroblasts, fibrosarcoma and hepatocellular carcinoma cells […”

Dexamethasone and transdehydroandrosterone significantly reduce pulmonary epithelial cell injuries associated with mechanical ventilation

“…Two types of fibers shape the cytoskeleton, namely, solid-like elastic fibers ( 45 ) and fluid-like viscous fibers ( 46 – 48 ). For a given mechanical load, a compliant cell will undergo more deformation than a stiff cell, and more fluid-like cells will dampen the force and will deform slower compared with highly elastic solid-like cells ( 49 ).…”