ABSTRACT

When biological cells migrate or tissues develop, they experience high strains and stresses. The cytoskeleton, a composite biopolymer network composed of three filament systems - intermediate filaments, actin filaments and microtubules - ensures that the cell is not damaged as a result of these strong deformations. While actin filaments and microtubules break easily under stain, as do their networks, intermediate filaments such as vimentin and keratin have been shown to be remarkably energy dissipating and extensible, up to several times their original length. At the single filament level, this behavior can be precisely characterized by optical tweezer experiments and can be traced back to a very distinct hierarchical molecular architecture consisting of alpha-helical coils in a massively parallel arrangement. While these results suggest that intermediate filaments serve as "safety belts" and "shock absorbers" for the cell, it is not yet entirely clear whether the intriguing single filament behavior is relevant at the cellular level. Therefore, we complement our single filament measurements with active microrheology on filament networks and with cell stretching studies. Through this work we hope to elucidate the role of intermediate filaments within the composite cytoskeletal network and the complex environment of a biological cell.

BIOSKETCH

Sarah Köster is a Professor of Experimental Physics at the University of Göttingen in Germany. She graduated from the University of Ulm with a Master’s in Physics in 2003 and earned a PhD in Physics from the University of Göttingen in 2006 after conducting her research work at the University of Ulm, Boston University and the Max Planck Institute for Dynamics and Self-Organization, Göttingen. In 2006 she joined the gropup of David Weitz at Harvard University as a postdoctoral fellow. In 2008 she became an assistant professor at the University of Göttingen. In 2011 she was tenured and promoted to associate professor, and in 2017 she was promoted to full professor. She is currently the spokesperson of the Condensed Matter Section of the German Physical Society and an elected member of the Review Board for Biological and Statistical Physics of the German Research Foundation. The Köster group studies the mechanical properties of cells, with a focus on the cytoskeleton, using both in vitro ("bottom-up") approaches and cell ("top-down") studies. They combine the different length scales from single proteins, to supramolecular assemblies and networks and to whole living cells, and are particularly interested in the intriguing material properties of biopolymers and how these properties are encoded in the molecular architecture.