Agenda de l'ENS de Lyon

As matter of fact, cell mechanical properties play an essential role in many cell biological processes, such as migration, differentiation, function, response to external stimuli and pathogenesis of several diseases. The mechanical properties of cells rely on dynamical organization of the cytoskeleton (CSK) and its interaction with the extracellular environment. Although remarkable advances have been made in cell mechanics in the last decades, a realistic mechanical model of living single cells is still missing.

 The aim of this interdisciplinary project was to study and quantify the mechanical properties of muscle cells, and to verify their possible alterations in CSK-perturbed and pathological conditions. Firstly, we combined experimental, modeling and analytical methods to decipher the normal mechanical behaviors of living C2C12 myoblasts (precursors of muscle cells) and myotubes (differentiated muscle cells) when probed with Atomic Force Microscopy (AFM) nanoindentation technique. The analytical method developed from these findings was then used in combination with morpho-structural analysis and pharmacological treatments to evaluate the role of both actomyosin dynamics and other active (ATP-depend) processes on myoblast mechanics.  Finally, the same AFM-based approach was applied to probe the deformability of primary human myoblasts from patient affected by Duchenne muscular dystrophy.

 We report that the mechanical response of normal living muscle cells to local deformation involves not only linear and non-linear elastic mechanisms, but also plastic events and viscous damping. The myoblast mechanical behavior is an active process, which deeply depends on CSK dynamics.