Cell stretching is amplified by active actin remodelling to deform and recruit proteins in mechanosensitive structures

Abstract

Detection and conversion of mechanical forces into biochemical signals control cell functions during physiological and pathological processes. Mechano-sensing is based on protein deformations and reorganizations, yet the molecular mechanisms in cells are still unclear. Using a cell stretching device compatible with super-resolution microscopy (SRM) and single protein tracking (SPT), we explored the nanoscale deformations and reorganizations of individual proteins inside mechano-sensitive structures. We achieved SRM after live stretching on intermediate filaments, microtubules and integrin adhesions. Simultaneous SPT and stretching showed that while integrins follow the elastic deformation of the substrate, actin filaments and talin also displayed lagged and transient inelastic responses associated with active acto-myosin remodeling and talin deformations. Capturing acute reorganizations of single-molecule during stretching showed that force-dependent vinculin recruitment is delayed and depends on the maturation state of integrin adhesions. Thus, cells respond to external forces by amplifying transiently and locally cytoskeleton displacements enabling protein deformation and recruitment in mechano-sensitive structures.

Recent Advances and Prospects in the Research of Nascent Adhesions

“…Recent experiments revealed that upon mechanical stretching (2 to 5%) FA integrin β3 displacements closely followed the substrate's elastic displacements (Massou et al, 2020). Such behavior revealed that most stationary integrins inside and outside of FAs remained connected to fibronectin.…”

“…Such behavior revealed that most stationary integrins inside and outside of FAs remained connected to fibronectin. Moreover, the same platform allowed to investigate whether proteins mediating a dynamic mechanical coupling of integrins to F-actin follow or deviate from integrins' elastic behavior (Massou et al, 2020). Massou et al concluded that the spatiotemporal force fluctuation in FAs probably emerges from the heterogeneous tensional/connective states of proteins at the nanoscale (Massou et al, 2020).…”

Molecular organization and mechanics of single vimentin filaments revealed by super-resolution imaging

“…The recent development of a cell-stretching device compatible with SRM methods, including SMLM, enables the exploration of protein deformation or reorganization upon mechanical strain. This technique also enables the study of the molecular mechanisms involved in mechano-sensitivity directly inside cellular structures (27). In this manuscript, we used SRM techniques to reveal the organization of vimentin filaments at the molecular scale directly inside cells and in vitro, providing us with important insights into the IF assembly mechanism.…”

“…The recent development of a cell-stretching device compatible with SRM methods, including SMLM, enables the exploration of protein deformation or reorganization upon mechanical strain. This technique also enables the study of the molecular mechanisms involved in mechano-sensitivity directly inside cellular structures (27).…”

Mechanical stretch scales centriole number to apical area via Piezo1 in multiciliated cells

“…However, their role in the regulation of centriole number and apical area remains unexplored. Finally, filamentous (F)-actin plays a critical role in mechanotransduction in all cells ( Massou et al, 2020 ; Wang, 2017 ). At the apical membrane, MCCs are enriched in F-actin and the apparent loss of apical F-actin in Piezo1-depleted cells may lead to defective mechanotransduction resulting in the defects in centriole amplification and apical area.…”