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BP: Fachverband Biologische Physik

BP 4: Cell Mechanics

BP 4.8: Vortrag

Montag, 23. März 2009, 16:30–16:45, HÜL 186

Contribution of cytoskeletal components to the nonlinear rheology of cells — •Navid Bonakdar¹, Philip Kollmannsberger¹, Karen Kasza², and Ben Fabry¹ — ¹Center for Medical Physics and Technology, Biophysics Group, Dept. of Physics, University of Erlangen-Nuremberg, Erlangen, Germany — ²School of Engineering and Applied Sciences, Harvard University, Cambridge, Mass., USA

The rheology of cells is governed by a creep or stress relaxation response that follows a weak power law over several decades in time, and a highly nonlinear stress-strain relationship, in particular a pronounced stress stiffening. In model cytoskeletal networks, stress stiffening is strongly increased in the presence of filamin A (FLNa), an F-actin crosslinker with the ability to unfold under force. The role of FLNa for the nonlinear rheology of living cells has so far not been characterized. We compared the stiffening response of a FLNa-deficient melanoma cell line (M2) and a variant stably transfected with FLNa (A7). Cell deformations in response to stepwise increasing forces applied to membrane-bound magnetic beads were analyzed using a non-linear superposition model to dissect stress relaxation from stress-stiffening responses. While stiffness and bead binding was reduced in FLNa-deficient cells, there was no difference in the degree of stress stiffening, indicating that contributions from other cytoskeletal components mask the effect of FLNa. The role of actin filaments, microtubules, intermediate filaments and myosin-generated cellular prestress in FLNa expressing and deficient cells was examined by pharmacological interventions.