Dresden 2017 – wissenschaftliches Programm

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BP: Fachverband Biologische Physik

BP 6: Cell Mechanics (Joint Session BP/DY)

BP 6.5: Vortrag

Montag, 20. März 2017, 16:15–16:30, SCH A251

Building up and force probing the microtubule cytoskeleton from scratch — •Matthias Koch^{1, 2} and Alexander Rohrbach¹ — ¹IMTEK, University of Freiburg, Germany — ²Lewis-Sigler Institute, Princeton University, USA

Eukaryotic cells are exposed to and driven by a large variety of forces or mechanical stimuli on a brought range of times scales. Due to their mechanical rigidity, microtubules are able to transport such stimuli enabling instantaneous mechanical integration of distant regions of a cell. However, only equilibrium mechanical properties of single microtubules have been characterized so far. We fill this void by using an in vitro bottom-up approach to determine the frequency response of single microtubules and small networks thereof that mimic the basic cytoskeletal structure. We combine a new scanned darkfield imaging technique with multiple time-shared optical tweezers to flexibly construct and force probe such networks with a well-defined, user-selected geometry over a broad frequency range. We report on a length dependent stiffening of individual microtubules above a physiologically relevant transition frequency between 1-30Hz due to the excitation of higher order bending modes which displays a mechanical high-pass filter with a tunable cutoff frequency. Furthermore, we identify and relate different mechanical responses of different network geometries to different functions inside the cell. The mechanistic comparison of basic network geometries to the known cytoskeletal topologies and the general function of different cell lines will substantially strengthen our understanding of the function and structure of the cytoskeleton.