Figure 2.

VEC expression modifies actin and vinculin organization in EC. VEC null and VEC positive cells formed morphologically different monolayers as observed at phase contrast (a and b). The organization of actin stress fibers was deeply modified by the expression of VEC (c and d). Actin stress fibers were thick and short in VEC positive cells (d) in comparison with the thin and elongated fibers in VEC null cells (c). Distribution of vinculin positive adhesion plaques (e and f) at the end of the actin stress fibers reflected the different setting of actin microfilaments. Vinculin positive plaques were numerous and marked the cell margins in VEC positive cells (f). They were few, thin, and mostly polar in VEC null cells (e). EC isolated from 9.0-d-postcoitum embyros with wild-type (h and l) or homozygous null mutation of VEC gene (g and i) showed differences in thickness and organization of actin stress fibers and vinculin positive adhesion plaques comparable with EC differentiated from embryonic stem (ES) cells. Cells in c–l were double stained for vinculin and actin. Black bar, 100 μm; white bar, 20 μm.