[The characteristics of actin cytoskeleton structure and its rearrangements by extracellular matrix proteins in normal, immortalized and transformed rat fibroblasts].

Comparative analysis of actin cytoskeleton structure in rat embryonic fibroblasts, E1A-immortalized and E1A + cHa-ras-transformed cells has been carried out. A decrease in adhesiveness and the rate of changes in actin cytoskeleton structures was shown to correlate with the level of morphological transformation of cells. E1A + cHa-ras-transformants show the lowest adhesiveness and complete disorganization of actin structures. Cultivation on serum-free media promoted disassembling of actin cytoskeleton structures in a small part of normal fibroblast population, only in a few immortalized cells, but exerted no influence on transformed cells. The influence of immobilized extracellular matrix proteins fibronectin, laminin and collagens type I and III on actin cytoskeleton structure in normal, immortalized and transformed fibroblasts was studied. Transformed cells spread on fibronectin completely restored highly organized actin structures, displayed a lot of stress fibers and focal contacts. The use of laminin revealed differences in locomotion between normal and transformed cells. Normal, immortalized and transformed fibroblasts spread on fibronectin and laminin demonstrate some peculiarities in actin cytoskeleton structures as a result of specificity of ligand-receptor interaction. Cells spread on fibronectin have polygonal shapes, many stress fibers and focal contacts, whereas cells spread on laminin are highly polarized and develop broad lamellae filled with actin microfilament meshwork. Collagens type I and III can affect adhesive properties and actin cytoskeleton structure in all cell lines studied only slightly, in comparison with fibronectin and laminin.