Vinculin E29R mutation changes cellular mechanics

We investigated the effect of the point mutation E29R on vinculin under cell mechanical aspects. MEFvcl KO cells were transfected with intact eGFP-vinculin (rescue) or mutant E29R vinculin. Cellular stiffness and adhesion strength of mutant E29R vinculin were considerably higher compared to rescue and MEFvcl KO cells. 2D traction microscopy also indicated markedly higher strain energy in E29R mutant cells compared to rescue and MEFvcl KO cells. Fluorescence recovery after photobleaching showed that the recovery time for mutant E29R cells was drastically slower than for MEFvcl rescue cells and that the mobile fraction was larger for rescue compared to E29R mutant cells. These results indicate that E29R mutation might prime the vinculin head for F-actin binding, which results in higher cell stiffness, contractile force, and strengthening of focal adhesions.