OB-III-2High-pressure microscopy for controlling the dynamics of microtubule cytoskeleton

Abstract

Microtubule (MT) is the cytoskeleton formed by the polymerization of tubulin, and cytoskeletal systems consisting of MTs are very dynamic and play many important roles in living cells, such as the morphogenesis of nerve cells and formation of the spindle apparatus during mitosis. Here, we focused on hydrostatic pressure to control the polymerization state of MTs within cell-sized giant liposomes (diameters ∼10 µm). Using real-time imaging with a high-pressure microscope (Fig. 1) [1–2], we examined the effects of hydrostatic pressure on the morphology of tubulin-encapsulating giant liposomes [3]. At ambient pressure (0.1 MPa), many liposomes formed protrusions due to tubulin polymerization within them. When high pressure (60 MPa) was applied, the protrusions shrank within several tens of seconds. This process was repeatedly inducible (around three times), and after the pressure was released, the protrusions regenerated within several minutes. These deformation rates of the liposomes are close to the velocities of migrating or shape-changing living cells rather than the shortening and elongation rates of the single MTs, which have been previously measured. These results demonstrate that the elongation and shortening of protrusions of giant liposomes is repeatedly controllable by regulating the polymerization state of MTs within them by applying and releasing hydrostatic pressure. !!...!!