Role of turn-over in active stress generation in a filament network

TL;DR

This study investigates how turnover of crosslinkers, motors, and filaments affects contractile stress in filament networks, revealing that turnover dynamics can prevent clustering and sustain steady-state contractility.

Contribution

It demonstrates that filament and crosslinker turnover can prevent clustering and maintain a dynamic contractile steady-state in filament networks.

Findings

Molecular motors generate contractile stress above a critical crosslinker number.

Passive crosslinker turnover leads to stress vanishing due to clustering.

Combined filament and crosslinker turnover prevents clustering and sustains contractility.

Abstract

We study the effect of turnover of cross linkers, motors and filaments on the generation of a contractile stress in a network of filaments connected by passive crosslinkers and subjected to the forces exerted by molecular motors. We perform numerical simulations where filaments are treated as rigid rods and molecular motors move fast compared to the timescale of exchange of crosslinkers. We show that molecular motors create a contractile stress above a critical number of crosslinkers. When passive crosslinkers are allowed to turn over, the stress exerted by the network vanishes, due to the formation of clusters. When both filaments and passive crosslinkers turn over, clustering is prevented and the network reaches a dynamic contractile steady-state. A maximum stress is reached for an optimum ratio of the filament and crosslinker turnover rates.