Tyrosine Phosphorylation of Vinculin at Position 1065 Modifies Focal Adhesion Dynamics and Cell Tractions

Focal adhesions (FAs) connect the cellular actin cytoskeleton via integrin with the extracellular matrix. They comprise of many structural and signaling proteins which are highly dynamic, well regulated, and responsible for the sensing of physical properties from the environment. Vinculin is a protein that incorporates all these functions. Here, we investigated the phosphorylation of Y1065 in the activation/regulation of vinculin. We used different vinculin mutants mimicking either a permanently activated or inhibited phosphorylation site at position 1065. Using these mutants, we determined their influence on the exchange dynamics and cell forces using fluorescence recovery after photobleaching and traction microscopy. The results indicate that phosphorylation at Y1065 significantly increases the amount of freely exchanging vinculin within FAs whereas inhibition of this phosphorylation site leads to an uncontrolled exchange of vinculin and reduced adhesive cell forces. In conclusion, we show that phosphorylation on position Y1065 is essential for accurate incorporation of vinculin into FAs and mechanical behavior of cells.