6th Annual Symposium
Physics of Cancer
Leipzig, Germany
September 7-9, 2015
Contributed Talk
Rheology of the active cell cortex in mitosis
Elisabeth Fischer-Friedrich1,2, Yusuke Toyoda2,3, Daniel Müller4, Anthony Hyman2, Frank Jülicher1
1Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
2Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
3Institute of Life Science, Kurume University, Kurume, Japan
4D-BSSE, Eidgenössische Technische Hochschule Zürich, Mattenstr. 26, 4058 Basel, Switzerland
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The cell cortex is a key structure for the regulation of cell shape and tissue organization. However, as the cell consists of several components, it is challenging to probe the mechanical response of the cortex exclusively. To reach a better understanding of the mechanics and dynamics of the cortex, we study here HeLa cells in mitotic arrest as a simple model system. In our assay, cells are dynamically compressed between two parallel plates. Investigating the mechanical response of cells at different equilibrium cell shapes, we find strong indications that the cortical layer is the dominant mechanical element as opposed to the cytoplasmic interior. To characterize the time-dependent rheological response, we perform oscillatory cell compressions. We extract a two-dimensional complex elastic modulus which characterizes the resistance of the cortex against area dilation. In this way, we present a rheological characterization of the cortical actomyosin network in live cells in the linear regime. Furthermore, we investigate the influence of actin cross-linkers and the impact of active prestress on rheological behavior. Notably, we find that cell mechanics in mitosis is captured by a simple rheological model characterized by a single time scale on the order of ten seconds which marks the onset of fluidity in the system.
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