It is well known that stress fibers of endothelial cells orient in a direction perpendicular to the stretch axis when subjected to cyclic stretch. However, little is known about the mechanism of this response. The main purpose of this study is to clarify the process of stress fiber's orientation and its relation to the focal adhesion. We grew HUVECs on deformable silicone membrane and subjected them to 22.5% uni-axial cyclic stretch for 30 to 140 minutes. Images of GFP-actin and Dsred-zyxin were taken every 30 seconds or 1 minutes. Though stress fiber's oriented in diverse ways, we were able to classify them into three types, rotation type, appear/disappear type, and recombination type. High resolution time-lapse imaging revealed the dynamic process of stress fiber orientation.
