The formation of filopodia bridge and intercellular nanotube : A Critical rule of torque and restorative force.*

In mammalian cells, a network of intercellular membrane nanotubes enables long-distance communication which is an intercellular transfer of cytoplasmic molecules and even organelles and viruses. The main component in filopodia which constitutes membrane intercellular nanotubes is consists of bundled actin filamentous. Also, several studies have confirmed the dynamic behavior of the filopodia which are undergoing restorative force by myosin II and torque by myosin V. Using a fluorescence imaging method, we have found that filopodia grown from two adjacent cells form the helical structure resulting. To understand the mechanism of forming the intercellular nanotube, we model a filopodium as a bundle of wormlike chains whose net persistence length is consistent with the value measured by our optical tweezers experiment. In this study, we quantitatively investigate the conformation, stability, and dynamics of the filopodia in comparison with the experiment by using the Langevin dynamics simulation. From the simulation results, we propose a region of a magnitude of tension and torque applied to the filopodia to form the nanotube