Orientation and shear mechanisms of finite deformation of the cell cytoskeleton

Abstract

This study presents a novel statistical-thermodynamic framework to model the finite deformation of the eukaryotic cell cytoskeleton, emphasizing the roles of actin filament orientation and bundle sliding. By introducing internal variables, such as an orientation order parameter and a microshear strain, the model captures the nonlinear mechanical response of the cytoskeleton under shear stress, including finite strain and critical damage dynamics. The free energy of the system is derived as a function of these variables, temperature, and a structural parameter that acts as an "effective temperature," reflecting the cytoskeleton's susceptibility to mechanical reorganization. Numerical simulations reveal distinct deformation regimes, from orientation ordering stage to failure, governed by the structural parameters. The results provide insights into the mechanobiology of cells, with potential applications in understanding pathological conditions and designing tissue engineering scaffolds.