Role of cytoskeleton network in anisosmotic volume changes of intact and permeabilized A549 cells

Abstract

Recently we found that cytoplasm of permeabilized mammalian cells behaves as a hydrogel displaying intrinsic osmosensitivity. This study examined the role of microfilaments and microtubules in the regulation of hydrogel osmosensitivity, volume-sensitive ion transporters, and their contribution to volume modulation of intact cells. We found that intact and digitonin-permeabilized A549 cells displayed similar rate of shrinkage triggered by hyperosmotic medium. It was significantly slowed-down in both cell preparations after disruption of actin microfilaments by cytochalasin B, suggesting that rapid water release by intact cytoplasmic hydrogel contributes to hyperosmotic shrinkage. In hyposmotic swelling experiments, disruption of microtubules by vinblastine attenuated the maximal amplitude of swelling in intact cells and completely abolished it in permeabilized cells. The swelling of intact cells also triggered ~10-fold elevation of furosemide-resistant (86)Rb+ (K+) permeability and the regulatory volume decrease (RVD), both of which were abolished by Ba2+. Interestingly, RVD and K+ permeability remained unaffected in cytocholasin/vinblastine treated cells demonstrating that cytoskeleton disruption has no direct impact on Ba2+-sensitive K+-channels involved in RVD. Our results show, for the first time, that the cytoskeleton network contributes directly to passive cell volume adjustments in anisosmotic media via the modulation of the water retained by the cytoplasmic hydrogel.

In vitroovicidal and larvicidal activities of some saponins and flavonoids against parasitic nematodes of goats

“…These alterations can be related with an increase of in-cell membrane permeability, yet without the presence of membrane rupture (Platonova et al . 2015). Gilabert-Oriol et al .…”

“…The apparent reduction of the cell, volume increase and the spherical shape might be an indicator of apoptotic cell death (Paris et al 2011). These alterations can be related with an increase of in-cell membrane permeability, yet without the presence of membrane rupture (Platonova et al 2015). Gilabert-Oriol et al (2013) related membrane permeabilising effects of digitonin on human urinary bladder carcinoma cell line (ECV-304).…”

Viscoelasticity and Volume of Cortical Neurons under Glutamate Excitotoxicity and Osmotic Challenges

“…The actin cortex, a thin, reversibly cross-linked actomyosin layer located directly beneath the plasma membrane (15), is known to play a major role in cell mechanics and morphology and is thought to oppose the intracellular osmotic pressure (16,17) (herein, the terms ''cortex'' and ''cortical'' are reserved for the intracellular actin layer unless noted otherwise). The contribution of the actin cytoskeleton to the cell volume regulation has previously been shown (14,18), but the precise mechanisms have yet to be elucidated. Changes in the cell volume, intracellular water content, and cytoplasmic viscosity also affect many internal physiological processes such as protein folding and binding kinetics, structural rearrangements, and transport phenomena that can be related to the phenomenon of the intracellular molecular crowding (11,12).…”

Channels and Volume Changes in the Life and Death of the Cell

“…This is modified only under pathologic conditions leading to hyponatremia or in other pathologies that alter the distribution of osmolytes in the extra-intracellular compartments (Song and Yu, 2014;Pedersen et al, 2016). The intracellular osmolarity also endures continuous variations owing to transient and local osmotic microgradients generated during physiologic processes, such as uptake and release of metabolites, cytoskeletal remodeling, synthesis and degradation of macromolecules, exocytosis and secretion (Pedersen et al, 2001;Strbák, 2011;Platonova et al, 2015). Even these localized changes in cell volume should be regulated to prevent changes in the concentration of molecules free in the cytosol, protein misfolding, or alterations in cell and organelle architecture.…”