Regensburg 2007 – scientific programme

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BP: Fachverband Biologische Physik

BP 5: Cell Adhesion

BP 5.7: Talk

Monday, March 26, 2007, 12:30–12:45, H44

Vinculin head and tail fragments control adhesion forces and cell mechanics — •Claudia Tanja Mierke, Philip Kollmannsberger, Gerold Diez, Daniel Paranhos Zitterbart, Ben Fabry, and Wolfgang Goldmann — Biophysics, University of Erlangen, Germany

The focal adhesion protein vinculin consists of a head-domain and a tail-domain. Our aim was to quantify cell mechanics and the strength of cytoskeleton, focal adhesion complex and integrin receptor bonds in F9wt mouse embryonic carcinoma cells, vinculin knock-out, vinculin re-transfected and two vinculin-mutants: vinculin-knock-out cells transfected with head-fragment (vin-head) and tail-fragment (vin-tail). We measured rupture forces and creep responses by applying a staircase-like sequence of step forces between 0.5-10 nN to fibronectin-coated magnetic beads attached to the cells. All cells displayed power-law creep responses, J(t)=J0 (t/t0)b, and in most cases linear stress stiffening. The power-law exponent b was taken as a measure of molecular bond stability, with lower values corresponding to more stable bonds. The inverse creep modulus 1/J0 was taken as a measure of cell stiffness. Our results show a significant reduction in bond strength and bond number in vinculin knock-out cells and vin-tail cells. Cell stiffness was reduced in vinculin knock-out cells and vin-head cells. The effect of vin knock-out is more prominently in MEF than in F9 cells indicating cell-type specific differences. Our results show that the head-domain of vinculin is involved in adhesion strength and tail-domain in whole cell mechanics.