Regensburg 2010 – scientific programme

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BP: Fachverband Biologische Physik

BP 32: Posters: Physics of Cells

BP 32.23: Poster

Thursday, March 25, 2010, 17:15–20:00, Poster B1

Vinculin regulates cell mechanical properties through src phosphorylation on its lipid anchor — •Nadine Lang, Gerold Diez, Wofgang Goldmann, and Ben Fabry — Biophysics Group, FAU Erlangen-Nürnberg, Germany

The focal adhesion protein vinculin links the actin cytoskeleton to integrin adhesion receptors.It has been reported that vinculin also binds to the lipid bilayer of the cell membrane.Vinculin with mutated or missing lipid binding regions leads to reduced focal adhesion turnover and decreased cell motility.We investigated whether this effect is directly caused by impaired lipid binding,or indirectly by mutations of residues on the lipid binding regions that are important for signaling.Vinculin has two lipid binding regions on its tail:one located on helix 3 has no phosphorylation sites,and another at the C-terminal(lipid anchor) which harbors a src-kinase regulated phosphorylation site at residue Y1065.Cells with mutations on helix 3 showed no change in stiffness (demonstrated by magnetic tweezer),in tractions(measured by traction microscopy)and in adhesion strength(determined by FN-coated bead detachment from the integrin receptor).In contrast,cells with missing lipid anchor or impaired lipid binding by mutating residues R1060 and K1061 showed strongly reduced stiffness,tractions and adhesion strength.Nearly identical behavior was observed if only the src phosphorylation site on the lipid anchor was mutated.These data show that lipid binding of vinculin's anchor is required for vinculin's mechano-coupling function, which in turn is regulated via src phosphorylation.Thus, vinculin is an important signaling protein in the FAC.