Force-Velocity Relationship in Branched Actin Networks: Consequences of Entanglement, Drag and Stall Force

TL;DR

This study combines simulations and theory to analyze how branched actin networks grow under load, revealing two regimes of velocity behavior influenced by entanglement, drag, and filament stall forces.

Contribution

It introduces a theoretical model linking network elasticity and filament entanglement to explain load-dependent velocity decay and identifies a critical stall force threshold for network growth.

Findings

Network velocity exhibits two regimes: finite at low stress and power-law decay at high stress.

Finite maximum velocity is governed by network drag.

Transition from stalled to growing network occurs when filament stall force exceeds a critical value.

Abstract

We investigate the growth of a branched actin network under load. Using a combination of simulations and theory, we show that the network adapts to the load and exhibits two regimes: a finite velocity at low stress, followed by a power-law decay of the velocity as a function of stress. This decay is explained by a theoretical model relating branched network elasticity to filament entanglement. The finite maximum velocity is attributed to network drag, which dictates dynamics at low stress. Additionally, analysis of filament stall force contribution reveals a transition from a stalled network to a growing network, when the filament stall force exceeds a critical value controlled by the applied stress.