Abstract
Actomyosin stress fibers, one of the main components of the cell’s cytoskeleton, provide mechanical stability to adherent cells by applying and transmitting tensile forces onto the extracellular matrix (ECM) at the sites of cell–ECM adhesion. While it is widely accepted that changes in spatial and temporal distribution of stress fibers affect the cell’s mechanical properties, there is no quantitative knowledge on how stress fiber amount and organization directly modulate cell stiffness. We address this key open question by combining atomic force microscopy with simultaneous fluorescence imaging of living cells, and combine for the first time reliable quantitative parameters obtained from both techniques. We show that the amount of myosin and (to a lesser extent) actin assembled in stress fibers directly modulates cell stiffness in adherent mouse fibroblasts (NIH3T3). In addition, the spatial distribution of stress fibers has a second-order modulatory effect. In particular, the presence of either fibers located in the cell periphery, aligned fibers or thicker fibers gives rise to reinforced cell stiffness. Our results provide basic and significant information that will help design optimal protocols to regulate the mechanical properties of adherent cells via pharmacological interventions that alter stress fiber assembly or via micropatterning techniques that restrict stress fiber spatial organization.Electronic supplementary materialThe online version of this article (doi:10.1007/s10237-015-0706-9) contains supplementary material, which is available to authorized users.
Highlights
A variety of cellular functions such as cell migration, proliferation, differentiation or metabolic activity require an exquisite dynamical tuning of the cell’s mechanical properties (Levental et al 2009; Fu et al 2010; Dupont et al 2011)
Mechanical stability is provided by its cytoskeleton (CSK), which is a hierarchical meshwork of polymeric proteins
We could quantify fiber alignment (FA), average fiber thickness (FT) and preferred radial location (RL) of the fibers for each cell, and we considered these three parameters to be independent from each other
Summary
A variety of cellular functions such as cell migration, proliferation, differentiation or metabolic activity require an exquisite dynamical tuning of the cell’s mechanical properties (Levental et al 2009; Fu et al 2010; Dupont et al 2011). Mechanical stability is provided by its cytoskeleton (CSK), which is a hierarchical meshwork of polymeric proteins. The CSK is actively involved in the application of forces onto cell–cell and cell– extracellular matrix (ECM) adhesions, having a crucial role in a plethora of cellular functions (Rodriguez et al 2003; Parsons et al 2010). Stress fibers are composed of antiparallel arrays of F-actin bundles (approximately 10–30 actin filaments) stabilized by actin-binding proteins and interleaved with the molecular motor nonmuscle myosin II (Thoresen et al 2011; Chang and Kumar 2013)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
