[Changes in the VASP expression feature of endothelial cells under steady laminar flow]

To investigate the effects of physiological shear stress on the vasodilator-stimulated phosphoprotein (VASP) location and expression changes associated with actin remodeling, we isolated and cultured human umbilical endothelial cells(HUVECs) with trypsin digestion. A parallel-plated flow chamber device was used to create laminar shear stress in vitro. The distributions of VASP and microfilaments in cells were observed by double staining with Alexa488 and rhodamine-phalloidin. Changes of VASP expression and phosphorylation were analyzed quantitatively with Western blot before and after exposure to shear flow for different times. We found that, under a shear stress of 10 dyn/cm2, HUVECs were elongated and oriented gradually to the flow direction. Microfilaments were recruited and oriented also to the flow direction with thicker VASP, specially targeted to their extremities. Western blotting data showed a rapid phosphorylation of VASP, and an increase of total VASP expression which peaked at 2 h (2 folds), then recovered until 8 h, followed by a slow increase again. These results suggest that VASP is a potential component which participates in the regulation of cell actin remodelling induced by shear flow.