Affiliations: Group Mechanics and Cell and Tissue Engineering, LEMTA‐UMR 7563 CNRS/INPL/UHP and IFR 111 Bioengineering, 54500 Vandoeuvre‐lès‐Nancy, France | Department of Pathophysiology, Medical College of Wuhan University, Wuhan, 430071, China
Note: [] Corresponding author: Dr. Xiong Wang, LEMTA‐UMR 7563 CNRS/INPL/UHP, 2 avenue de la Foret de Haye, 54500 Vandoeuvre‐lès‐Nancy, France. Tel: + 33 3 83 59 57 36; Fax: +33 3 83 59 55 51; E‐mail: Xiong.Wang@ensem.inpl‐nancy.fr.
Abstract: Vasodilator‐stimulated phosphoprotein (VASP), an actin filaments‐associated protein expressed mainly in focal adhesions and dynamic membrane regions of endothelial cells (ECs), serves as a substrate for cAMP and cGMP‐dependent protein kinases. In this work, we studied the effect of laminar shear stress in vitro on the location and expression of the VASP as well as its phosphorylation associated with actin reorganisation in human umbilical endothelial cells (HUVECs). The distributions of VASP and microfilaments were observed by a fluorescent double staining. The level of VASP expression in cells was quantified by western blot. Experiments showed that, after exposure to a shear stress of 10 dyn/cm2 for 24 h, besides the elongation and orientation of the cells, and spots of VASP were found along thick stress fibres, particularly at their two extremities. Western blot data showed conversions up to 11.4% and 8.9% of the 46 kD non‐phosphorylated form VASP to its 50 kD phosphorylated form after exposures of 1 h and 4 h respectively to the same shear stress. The shear stress of 15 dyn/cm2 had qualitatively the same effect as that of 10 dyn/cm2, but with a lower magnitude. However, the shear stress of 2 dyn/cm2 had much slower and weaker effects on the same tendency. These results suggest that a laminar shear stress can induce VASP translocation and phosphorylation that proceed actin filaments rearrangement along with the flow direction in HUVECs.
