Hierarchical self-organization of cytoskeletal active networks

TL;DR

This study combines experiments and simulations to explore how actin filaments and myosin motor clusters self-organize into complex structures like bundles and asters, revealing hierarchical processes underlying cellular organization.

Contribution

It introduces a combined experimental-computational approach to elucidate the hierarchical self-organization of cytoskeletal networks involving motor protein clusters.

Findings

Large-scale patterns include bundles, asters, and networks.

Motor oligoclusters facilitate high-connectivity junctions.

Self-organization proceeds hierarchically from microscopic to macroscopic scales.

Abstract

The structural reorganization of the actin cytoskeleton is facilitated through the action of motor proteins that crosslink the actin filaments and transport them relative to each other. Here, we present a combined experimental-computational study that probes the dynamic evolution of mixtures of actin filaments and clusters of myosin motors. While on small spatial and temporal scales the system behaves in a very noisy manner, on larger scales it evolves into several well distinct patterns such as bundles, asters, and networks. These patterns are characterized by junctions with high connectivity, whose formation is possible due to the organization of the motors in "oligoclusters" (intermediate-size aggregates). The simulations reveal that the self-organization process proceeds through a series of hierarchical steps, starting from local microscopic moves and ranging up to the macroscopic large scales where the steady-state structures are formed. Our results shed light into the mechanisms involved in processes like cytokinesis and cellular contractility, where myosin motors organized in clusters operate cooperatively to induce structural organization of cytoskeletal networks.