Dresden 2009 – scientific programme

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BP: Fachverband Biologische Physik

BP 19: Cell Adhesion

BP 19.5: Talk

Thursday, March 26, 2009, 12:00–12:15, ZEU 260

Vinculin lipid anchorage influences focal adhesion strength and turnover — •Lang Nadine, Gerold Diez, Thorsten Bloem, Philip Kollmannsberger, Ben Fabry, and Wolfgang Goldmann — Biophysics Group,Departmet of Physics, University of Erlangen-Nuremberg

The focal adhesion protein vinculin links the actin cytoskeleton to other proteins within the focal adhesion complex and plays an important role in cell adhesion and migration. To function properly vinculin needs to bind to the cell lipid membrane but the mechanism is currently not well understood.A lipid-membrane binding site,called lipid anchor, is located at the C-terminus of the vinculin tail. We measured the mechanical behavior of vinculin knock-out mouse embryonic fibroblast cells transfected with EGFP-linked-vinculin deficient of the lipid anchor (vinDeltaC).A magnetic tweezer was used to determine cell stiffness and binding strength.Compared to wildtype and rescue both were reduced in vinDeltaC cells suggesting that lipid binding of vinculin is important for the stability of the focal adhesion complex.Vinculin dynamics in focal adhesions measured with FRAP showed decreased turnover rates of vinDeltaC compared to wild-type vinculin. Because the lipid anchor also contains a c-SRC phosphorylation site we repeated these measurements in cells transfected with full length vinuclin in which either the c-SRC phosphorylation site or the lipid binding sites were scrambled.In both cases we found decreased adhesion strength, suggesting that lipid binding of vinculin and phosphorylation by c-SRC are important for mechanical stability of focal adhesions.