Regensburg 2010 – wissenschaftliches Programm

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SYDI: Symposium SKM Dissertation Prize 2010

SYDI 1: SKM Dissertation Prize 2010

SYDI 1.1: Hauptvortrag

Dienstag, 23. März 2010, 13:30–14:00, H10

Modeling the coupling of mechanics and biochemistry in cell adhesion — •Achim Besser — Harvard Medical School, Department of Cell Biology, 240 Longwood Ave, Boston MA 02115, USA.

To probe the mechanical properties of their environment, adherent cells actively generate forces which are converted into biochemical signals at sites of adhesion. These biochemical signals diffuse into the cell and modify force generation, thus leading to a closed mechano-chemical feedback cycle. A dynamical systems analysis has been performed which demonstrates that this feedback cycle acts as a bistable switch that allows cells to discriminate between soft and stiff environments. We first present an analytically solvable mechanical model for the main force-generating element in adherent cells, so-called stress fibers, which are actin filament bundles contracted by myosin motors. Our model combines passive viscoelasticity with active contractility and shows excellent agreement with experimental data on stress fiber contraction dynamics after laser surgery. Next the stress fiber model is coupled to a reaction diffusion system describing the signaling pathway that is initiated at sites of adhesion. A bifurcation analysis reveals that the coupled system is bistable as a function of environmental stiffness. This should give rise to hysteresis in the cellular traction forces when cells are exposed to substrates of time-dependent stiffness.