Self-organization in systems of treadmilling filaments.

The cytoskeleton is an important substructure of living cells, playing essential roles in cell division, cell locomotion, and the internal organization of subcellular components. Physically, the cytoskeleton is an active polar gel, that is, a system of polar filamentous polymers, which is intrinsically out of thermodynamic equilibrium. Active processes are notably involved in filament growth and can lead to net filament assembly at one end and disassembly at the other, a phenomenon called treadmilling. Here, we develop a framework for describing collective effects in systems of treadmilling filaments in the presence of agents regulating filament assembly. We find that such systems can self-organize into asters and moving filament blobs. We discuss possible implications of our findings for subcellular processes.