[The reorganization of actin cytoskeleton and microtubule system of human endothelial vein in the intercellular contacts formation].

ABSTRACT

Endothelial cells are tightly fitted to each other and lining the interior surface of all vessels of living organism to provide vascular permeability regulation and interchange between the blood circulating in vessels and tissue fluids of those organs in which these vessels are located. In vitro endothelial monolayer conserve it's basic barrier function which is native for vessels endothelium. Based on this fact we used endothelial cells growing in vitro as a model system in experimental studies of cytoskeletal and adhesion cell components interaction. In current paper, cultured human vein endothelial cells monolayer was used to quantify cytoskeleton alterations in the of endothelial cells from spreading and formation of the first cell-cell contacts to confluent monolayer formation. The system of actin filaments formed two different cytoskeletal structures in the cells of venous endothelium 1) cortical actin network; 2) actin stress fibers (bundles) arranged parallel to the substrate. Two actin isoforms, ß- and γ-cytoplasmic (non-muscle) actins, are expressed in endothelial cells. The bundles of actin stress fibers were detected by immunofluorescent staining with antibody against ß-actin, whereas antibodies against γ-actin identified cortical and lamellar networks. For assessment of the actin cytoskeleton organization it's fluorescence intensity on the area of 10 µM2 located (1) near the free edge, and (2) in the zone of cell-cell contacts were analyzed. Fluorescence intensity of ß-actin structures was higher in the areas of cell-cell contact. The fluorescence of γ-actin structures was more intensive at the leading edges of the lamellae, and was the lowest on the stable edges of the cells with formed cell-cell contacts. The endothelial monolayer formation was accompanied by microtubule system alteration the number of microtubules increased at the cell edge, and besides the microtubules quantity in the area of already formed cell-cell contact was always higher than in free lamella region.