Dynamic remodeling biopolymer networks achieve mechanical homeostasis*

The actin cortex is a biopolymer network consisting of actin filaments and actin binding proteins, along with molecular motors that actively stress the network. This network is known to undergo rapid turnover, where filaments are disassembled and polymerized dynamically while maintaining rigid mechanical properties. The fundamental processes that regulate the remodeling process (such as polymerization and depolymerization) are known, but the precise mechanisms that connect the physics of remodeling to the maintenance of mechanical properties during turnover remain elusive. Here, we perform simulations of prestressed disordered central-force spring networks that undergo successive edge pruning and insertion events that alter the network topology while preserving certain characteristics such as total filament mass and filament length distribution. The networks undergo substantial remodeling and achieve mechanical homeostasis for reasonable values of prestress when pruning is performed with a tension-based criterion. Our work offers important insight into how the interplay between polymerization and depolymerization during turnover contributes to the rigidity of the cytoskeleton.