Molecular Basis of Mechanotransduction in Living Cells

Abstract

The simplest cell-like structure, the lipid bilayer vesicle, can respond to mechanical deformation by elastic membrane dilation/thinning and curvature changes. When a protein is inserted in the lipid bilayer, an energetic cost may arise because of hydrophobic mismatch between the protein and bilayer. Localized changes in bilayer thickness and curvature may compensate for this mismatch. The peptides alamethicin and gramicidin and the bacterial membrane protein MscL form mechanically gated (MG) channels when inserted in lipid bilayers. Their mechanosensitivity may arise because channel opening is associated with a change in the protein's membrane-occupied area, its hydrophobic mismatch with the bilayer, excluded water volume, or a combination of these effects. As a consequence, bilayer dilation/thinning or changes in local membrane curvature may shift the equilibrium between channel conformations. Recent evidence indicates that MG channels in specific animal cell types (e.g., Xenopus oocytes) are also gated directly by bilayer tension. However, animal cells lack the rigid cell wall that protects bacteria and plants cells from excessive expansion of their bilayer. Instead, a cortical cytoskeleton (CSK) provides a structural framework that allows the animal cell to maintain a stable excess membrane area (i.e., for its volume occupied by a sphere) in the form of membrane folds, ruffles, and microvilli. This excess membrane provides an immediate membrane reserve that may protect the bilayer from sudden changes in bilayer tension. Contractile elements within the CSK may locally slacken or tighten bilayer tension to regulate mechanosensitivity, whereas membrane blebbing and tight seal patch formation, by using up membrane reserves, may increase membrane mechanosensitivity. In specific cases, extracellular and/or CSK proteins (i.e., tethers) may transmit mechanical forces to the process (e.g., hair cell MG channels, MS intracellular Ca(2+) release, and transmitter release) without increasing tension in the lipid bilayer.

Cytoskeletal Tension Regulates Both Expression and Degradation of h2-Calponin in Lung Alveolar Cells

“…Therefore, the isometric tension, other than tension dynamics, determines the expression of h2-calponin. The tension regulation of h2-calponin synthesis and degradation demonstrate a novel mechanical regulation of cellular biochemistry.Living cells respond to mechanical forces by changes in cellular structure and function through gene regulation and posttranslational protein modification (1)(2)(3)(4)(5). Reorganization of the cytoskeleton is a key component of the cellular response to mechanical stimuli (3,6).…”

Imprinting, latchment and displacement: a mini review of early instinctual behaviour in newborn infants influencing breastfeeding success

“…Their main function is as a mechanoreceptor of tactile stimuli. Mechanotransduction as part of our evolutionary process dates back to single cell organisms 1.7 billion years ago 23.…”

Détecter la pression ?

“…Ces courants, définis par leurs proprié-tés d'adaptation, sont responsables de l'activation des neurones impliqués dans le toucher, la proprioception ou la douleur. Un certain nombre de canaux ioniques activés mécaniquement ont été décrits à ce jour [3,4] Figure 1. Courants activés par la stimulation mécanique des corps cellulaires de cellules exprimant Piezo1 ou Piezo2.…”

“…De ce fait, ces cellules souches sont devenues, au cours des dernières années, un modèle cellulaire passionnant au coeur de nombreuses études sur la régénération tissulaire. Identifier, isoler et apprendre à utiliser des cellules souches adultes pour la médecine régéné-ratrice est ainsi devenu un enjeu majeur de la recherche biomédicale [3,4].…”

“…La douleur, la proprioception, le contrôle du tonus vasculaire ou du flux rénal, l'homéostasie musculaire et osseuse ainsi que l'embryogenèse sont autant d'exemples de processus contrôlés par des forces mécaniques [3,4].…”