Dresden 2006 – scientific programme

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AKB: Biologische Physik

AKB 11: Cell Adhesion I

AKB 11.3: Talk

Tuesday, March 28, 2006, 12:30–12:45, ZEU 260

Theoretical and experimental studies of force induced growth of focal adhesions — •Achim Besser¹, Patrick Heil², Joachim P. Spatz², and Samuel A. Safran³ — ¹Center for Modelling and Simulation in the Biosciences, University of Heidelberg, INF 293, 69120 Heidelberg, Germany — ²Dept. Biophysical Chemistry, University of Heidelberg, INF 253, 69120 Heidelberg, Germany — ³Dept. Materials and Interfaces, The Weizmann Institute of Science, 76100 Rehovot, Israel

Focal adhesions are µ m-sized protein aggregates that connect the actin cytoskeleton to the extracellular matrix, a network of macro-molecules surrounding tissue cells. Experiments show that as the force acting through the actin cytoskeleton is increased, focal adhesions grow in size and in the direction of the force. We consider a model for the adsorption of adhesion proteins from the cytoplasm to the adhesion site and the resulting force-sensitive anisotropic growth. The theory couples the mechanical forces to the adsorption dynamics. We derive the velocity of both the front and back of the adhesion as a function of the applied force. In addition, our results show that the relative motion of the front and back of the adhesion is asymmetric and in different ranges of forces, the adhesion shrinks or grows in the direction of the force.

These force-induced shape adaptations of focal adhesions are visualized in our experiments by means of fluorescence microscopy. The application of a micro-mechanical device allows the exertion of forces in the nN regime on the cell and thereby controlled stimulation of adhesion growth. The obtained experimental data is in line with the qualitative predictions of our model.