BP Seminar 15

Sponsored by:The Biophysical Society of Japan & Acaric.co.ltd.

Reconstitution of actin cytoskeletal dynamics and functions

The actin cytoskeleton regulates various essential functions of the cell, including cell division, motility, and polarity establishment. Ultrastructural and molecular biological studies have revealed, step by step, the nanoscale structures, molecular components, and signaling cascades that regulate the cytoskeletal assembly/disassembly process. However, it remains a mystery how these tiny molecules self-organize into cell-scale structures and work together to drive biological functions. To uncover the physical principles that govern the cytoskeletal assembly, we have adopted an in vitro reconstitution approach. We developed a minimal cell model by encapsulating purified cytoskeletal proteins or the cytoplasmic extracts of living cells into cell-sized capsules surrounded by a lipid membrane. We also developed a method to reconstitute the actin cytoskeleton on a patterned array of lipid membranes. This bottom-up approach allows for precise and independent control of biochemical and physical parameters such as molecular components, their activities, and the size and shape of the boundary. Using these in vitro systems, we are seeking biochemical and physical conditions under which structures and functions seen in living cells are reconstituted. In this seminar, I will present our recent efforts in reconstituting the actin cytoskeletal dynamics and cell functions including cell motility. I will also discuss the impacts of high-resolution live imaging for data analysis.