Force generation at microtubule ends : An in vitro approach to cortical interactions.

Abstract

Biopolymers are essential for cellular organization. They bridge the cell interior forming a framework that is used as a reference frame for different cellular organelles. Interestingly this framework, called the cytoskeleton, is not static but constantly reorganizes. The dynamics of the cytoskeleton allow the cell to rearrange its interior for various processes, such as cell division. This dynamic reorganization relies, at least partly, on forces that arise from assembly and disassembly of cytoskeletal biopolymers. The work presented in this thesis focuses on microtubules, a particular biopolymer. In vivo microtubules regularly grow into physical boundaries, like the cell cortex or cellular organelles, where assembly and disassembly forces are generated. We study different mechanisms of microtubule force generation and the regulation of microtubule dynamics by these generated forces. The interactions with physical boundaries are assessed in minimal in vitro experiments that allow for systematic analysis of isolated mechanisms. In addition, simple computer simulations and mathematical modeling are performed to explain the experimental findings and to investigate the consequences of the findings for other in vitro and in vivo systems.