Modeling and Predicting the Behaviors of Cytoskeletal Networks

Cytoskeletal networks drive many cellular and morphological processes such as spindle organization and apical constriction. Although cytoskeletal components and their properties are known, we still lack an intuitive understanding of how cytoskeletal networks behave. Here, I describe an analytical theory that predicts whether a network will contract, expand, or conserve its dimensions. This analytical theory correctly predicts the behavior of simulated networks, consisting of filaments with varying combinations of connectors and motors. We find that contraction is the dominant behavior of networks with semi-flexible filaments, such as F-actin. By contrast, networks of rigid filaments, such as microtubules, can be either contractile or extensile, and the theory reveals unexpected modes for network expansions that do not depend on de novo assembly of filaments. Our results suggest that pulsatility is an intrinsic behavior of contractile networks if the filaments are not stable but turn over. The theory offers a unifying framework to think about mechanisms of contractions or expansion and allows for a qualitative prediction of their time-evolution. It provides the foundation for studying a broad range of processes involving cytoskeletal networks and a basis for designing synthetic networks.