The Interplay of Nonlinearity and Architecture in Equilibrium Cytoskeletal Mechanics

TL;DR

This study models cytoskeletal networks as nonlinear elastic structures to explore how architecture and nonlinearity influence cellular mechanical stability and phase behavior.

Contribution

It introduces a minimal amorphous network model combining simulations and theoretical analysis to reveal diverse stable phases and glass transition conditions.

Findings

Identification of multiple thermodynamic phases depending on network parameters

Network connectivity influences phase boundaries and glass transition density

Estimation of kinetic glass transition densities in cytoskeletal models

Abstract

The interplay between cytoskeletal architecture and the nonlinearity of the interactions due to bucklable filaments plays a key role in modulating the cell's mechanical stability and affecting its structural rearrangements. We study a model of cytoskeletal structure treating it as an amorphous network of hard centers rigidly cross-linked by nonlinear elastic strings, neglecting the effects of motorization. Using simulations along with a self-consistent phonon method, we show that this minimal model exhibits diverse thermodynamically stable mechanical phases that depend on excluded volume, crosslink concentration, filament length and stiffness. Within the framework set by the free energy functional formulation and making use of the random first order transition theory of structural glasses, we further estimate the characteristic densities for a kinetic glass transition to occur in this model system. Network connectivity strongly modulates the transition boundaries between various equilibrium phases, as well as the kinetic glass transition density.