Dissipation of Stress in the Cytoskeleton VIA Alpha-Actinin Dynamic Crosslinking

Other conference contribution, 2016

The actin cytoskeleton is known to be a main structural and mechanical component of many eukaryotic cells. Dynamic crosslinking of actin filaments by proteins such as alpha-actinin, can change these mechanics, however, the effect of dynamic crosslinking on cell mechanics has not been previously reported. Here we quantify the viscoelastic moduli of cells with alpha-actinin isoforms that have varied binding affinity.
We apply several techniques, including passive and active micro-rheology and AFM measurements to measure cellular moduli with alpha-actinin isoforms. The experiments are also performed after myosin inhibition and ATP depletion to study the contribution of active contractility to the viscoelastic properties of these cells. AFM-based stress relaxation and dynamic indentation tests are used to calculate the mechanical properties of the cellular cortex, while active micro-rheology using optical tweezers allows us to calculate the storage and loss moduli of the cytoplasm.
Furthermore, the overall energy dissipation is estimated at cellular level, and these results are compared with cell work on the elastic substrates, using traction force microscopy data. Energy dissipation via dynamic crosslinkers in the cytoskeleton can regulate cellular viscoelasticity and basic biological functions such as spreading, force-generation, and migration.