Optimal cytoskeletal filament dynamics for intracellular transport

The transport of cargo within cells is typically caried out by a combination of active motor-driven motion on cytoskeletal filaments and diffusion in the cytoplasm. It is known that the morpholgy of the cytoskeletal network differs between cell types and plays a significant role in determining transport. However, the network is not static but can turnover on the same time scale as the transport of cargo on the network. Here, we study the transport of cargo carried by myosin motors on a dynamic actin network. We use a stochastic simulation model that accounts for both active transport along filaments as well as passive diffusion in the cytoplasm and incorporates the dynamics of the explicitly represented actin network. We show how filament treadmilling rates affect cargo transport along with filament lengths, densities and motor attachment/detachment rates. In particular, using simulations and simple analytics, we show that the turnover rates of the network can be optimized for fast transport and that the optimal dynamics regime is consistent with in vivo conditions. Additionally the optimal regime can be tuned by both cargo properties and filament densities and lengths suggesting new ways for cells to regulate transport.