Focal adhesion proteins link cell surface integrins and intracellular actin 
stress fibers and therefore play an important role in mechanotransduction and 
cell motility. When endothelial cells are subjected to cyclic mechanical strain, 
time-lapse imaging revealed that cells underwent significant morphological 
changes with their resultant long axes aligned away from the strain direction. 
To explore how this response is regulated by focal adhesion-associated proteins 
the expression levels of paxillin, focal adhesion kinase (FAK), and zyxin were 
knocked down using gene silencing techniques. In addition, rescue of endogenous 
and two mutant zyxins were used to investigate the specific role of zyxin 
interactions. Cells with decreased zyxin expression levels and rescue with the 
mutant lacking zyxin/alpha-actinin binding exhibited lower orientation angles 
after comparable times of stretching as compared to normal and control cells. 
However, knockdown of the expression levels of paxillin and FAK and rescue with 
the mutant lacking zyxin/VASP (vasodilator-stimulated phosphoprotein) binding 
did not significantly affect the degree of cell orientation. In addition, wound 
closure speed and cell-substratum adhesive strength were observed to be 
significantly reduced only for cells with zyxin depletion and the mutation 
lacking zyxin/alpha-actinin binding. These results suggest that zyxin and its 
interaction with alpha-actinin are important in the regulation of endothelial 
cell adhesive strength, motility and orientation response to mechanical 
stretching.