THE REORGANIZATION OF ACTIN CYTOSKELETON AND MICROTUBULE SYSTEM
OF HUMAN ENDOTHELIAL VEIN IN THE INTERCELLULAR CONTACTS FORMATION
A.S. Shahov, V.B. Dugina, I.B. Alieva 1
Electron Microscopy Department, A.N. Belozersky Institute of Physical and Chemical Biology,
Moscow State University;
1 e-mail: irina_alieva@belozersky.msu.ru
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, β- 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 β-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 β-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.
Key words:
endothelium, the cytoskeleton of endothelial cells, γ-actin, β-actin, microtubules
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