External seminar - Matsubayashi Hideaki (Tohoku University)

Abstract:

Actin polymerization and the associated force generation are central to diverse cellular processes, including motility, division, and membrane trafficking. A bottom-up reconstitution approach in giant unilamellar vesicles (GUVs) represents a particularly powerful strategy for investigating these processes, as it captures essential membrane–cytoskeleton interactions under well-defined conditions and offers a valuable testbed for theoretical models. However, achieving precise spatiotemporal control of actin dynamics within GUVs remains challenging, in part due to the barriers posed by the lipid membrane. To address this issue, we developed a molecular tool that provides spatiotemporal control of actin nucleators at target locations in response to external signals. First tested in mammalian cells, we show that our system can drive local morphological changes in targeted organelles. In GUVs, we leveraged external chemical cues to trigger symmetry breaking and membrane deformation. Furthermore, using light-induced actin polymerization, we found that directing actin activation toward specific regions of the vesicle led to unidirectional movement of GUV. Notably, our findings suggest a synergistic interplay between branched and linear actin filaments in those vesicle movements, highlighting the cooperative nature of two distinct actin nucleators. Our approach offers a powerful platform for investigating cytoskeletal dynamics from a bottom-up perspective, as well as designing synthetic cells with self-propelled properties.