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Nanomagnetic Actuation: Controlling Cell Behavior with Magnetic Nanoparticles
Published in Jeffrey N. Anker, O. Thompson Mefford, Biomedical Applications of Magnetic Particles, 2020
The precise methods by which the various cell types monitor and respond to mechanical stimuli are not fully understood. However, the methods by which cells attach and monitor their various extracellular matrices, share numerous commonalities. One such method is by attaching directly to the extracellular matrix via transmembrane glycoproteins known as cell surface integrins. These heterodimeric proteins consist of two distinct subunits known as α and β. There are currently 16α and 9β subunits known to exist, which can combine to form a variety of integrins with distinct binding specificities. The intracellular region of the α chain is physically connected to the cytoskeleton via interaction with talin, vinculin, and α-actinin. It is this connection that enables integrins to transduce mechanical stimuli from the extracellular matrix into the intracellular environment (Burridge et al. 1988).
Cell Adhesion in Animal Cell Culture: Physiological and Fluid-Mechanical Implications
Published in Martin A. Hjortso, Joseph W. Roos, Cell Adhesion, 2018
Manfred R. Koller, Eleftherios T. Papoutsakis
Close contacts are characterized by a 30–50-nm spacing between the cell surface and the substratum and are broad areas that are often found surrounding sites of focal adhesion. A meshwork of actin microfilaments that stains positively for α-actinin is often seen subtending the membrane at these sites. All close-contact sites stain moderately for fibronectin, but are negative for vinculin, suggesting that they are similar to the more predominant type of ECM contact discussed above. In early culture, close contacts were numerous in forming 50% of the cell-substratum contacts, but this number declined sharply to 10% in late culture. Close contacts were found to comprise 40% of the cell-cell contacts in late culture, making close contacts the most abundant type of cell-cell contact between fibroblasts.
Filament-motor protein system under loading: instability and limit cycle oscillations
Published in Soft Materials, 2021
Amir Shee, Subhadip Ghosh, Debasish Chaudhuri
In Figure 5, we show how the onset of stable limit cycle oscillations () depends on the number of MPs recruited for a given rigidity of the elastic loading. The plot uses parameter values corresponding to microtubule-kinesin MP assay, at an ATP concentration of mM. The minimum number of MPs required for the onset of spontaneous oscillations increases with the stiffness of the substrate. While the particular calculations are performed for microtubule-kinesin system, the physical mechanism is equally applicable for acto-myosin systems. Our simple setup has a parallel in the rigidity sensing by cells, where contractile acto-myosin system couples to the extra-cellular matrix (ECM) via an adhesion complex consisting of alpha-actinin and integrin .[26,27] The range of values used in Figure 5 belongs to the range of rigidities of sub-micron elastomeric pillars used in cell spreading experiments .[27] The cell may utilize an increase of processive myosin bundles, required for the onset of oscillations (tugging), as a strategy to sense the ECM stiffness .[27,28] In fact, larger multifilament assemblies of myosin is noted near more rigid substrate .[27]
The stiffness response of type IIa fibres after eccentric exercise-induced muscle damage is dependent on ACTN3 r577X polymorphism
Published in European Journal of Sport Science, 2019
Siacia Broos, Laurent Malisoux, Daniel Theisen, Ruud Van Thienen, Marc Francaux, Martine A. Thomis, Louise Deldicque
In addition, α-actinin-3 deficiency may influence susceptibility to exercise-induced muscle damage. The α-actinin proteins are the main building blocks of the Z-disc, which is the most vulnerable structure of the sarcomere for exercise-induced muscle damage (Cheung, Hume, & Maxwell, 2003). Normally, α-actinin-3 is expressed in fast twitch fibres, while α-actinin-2 is present in all fibre types (North & Beggs, 1996). As XX genotypes do not express α-actinin-3 in their muscles, the Z-discs of their fast muscle fibres are composed only of α-actinin-2. The different build-up of fast fibre Z-discs between RR and XX genotypes could influence the susceptibility for exercise-induced muscle damage.
Association between COMT Val158Met polymorphism and competition results of competitive swimmers
Published in Journal of Sports Sciences, 2018
Daisuke Abe, Hirokazu Doi, Taishi Asai, Mayuko Kimura, Tadashi Wada, Yuusuke Takahashi, Takaaki Matsumoto, Kazuyuki Shinohara
With regard to the factors that determine the competitive performance of individual athletes, recent studies have revealed association between the physiological characteristics of individual athletes and specific genetic polymorphisms. A well-known genetic polymorphism affecting physical ability is that in the ACTN3 gene, which encodes α-actinin-3, a protein found in the muscle that affects muscular contraction speed and endurance. Yang et al. (2003) reported that among athletes, those with the explosive power-type polymorphism of ACTN3 showed significantly higher physical performance in several sports, including swimming, water polo, and wrestling.