Design principles for intracellular road networks

Intracellular transport of vesicles and organelles is typically carried out by a combination of diffusion and active, motor-driven transport along networks of actin and microtubule cytoskeletal filaments. Perturbations to transport can significantly impact cellular viability and can result in disease at the organismal scale. While much work in the past has focused on how motor properties affect transport, there has been growing interest in how the architecture and properties of the cytoskeletal network influence transport. Network features, characterized by the density, lengths, locations, orientations, and connectivity of filaments, as well as defects and blockades along them likely influences intracellular transport in much the same way that road connectivity and conditions are critical determinants of vehicular traffic. In this talk, I shall focus on some recent work that highlights the importance of these features. At the level of a single filament, I shall discuss how defects and obstacles along the filament can manifest themselves in anomalous transport properties. At the network scale, I will argue that that the actual architecture of the network is critical. I will discuss how, for example, particular filament arrangements can result in “traps” near the nucleus that result in highly variable transport times, while other architectures result in rapid directed transport. In all cases, I shall highlight some potential strategies that cells can exploit to promote efficient and robust transport.