[Differences in the character of interaction of normal and transformed human keratinocytes with laminin isoforms]. / Razlichiia v kharaktere vzaimodeistviia normal'nykh i transformirovannykh keratinotsitov cheloveka s izoformami laminina.

Laminins constitute a family of heterotrimeric glycoproteins of basement membranes. Laminins promote cell adhesion, migration, growth, and differentiation. So far, at least 12 different isoforms of laminin have been known. However, no sufficient knowledge is available on the nature of cell response on different laminins. The study was aimed to compare adhesive properties of two laminin isoforms, laminin-1 and laminin-2/4, with respect to normal (freshly isolated keratinocytes) and transformed (A-431) human skin cells. We have used the following assays: cell adhesion to the substrate covered with laminin isoformes, interaction of latex beads (D = 1 micron) coated with the same proteins with cells in suspension, and a comparative study of the cytoskeleton structure of cells spread on the immobilized laminins. It was demonstrated that laminin-2/4 is a more effective potent promotor of adhesion for both normal keratinocytes and transformed A-431 cells, compared with laminin-1. A comparison of many attached protein-covered beads allowed to estimate a relative quantity of cell surface receptors to laminin isoforms in different cell types. The relative number of receptors to laminin-2/4 on the keratinocyte surface is 7 times higher than that to laminin-1 after a 30 min incubation with cells, and is 6 times higher after 1 hour. As for A-431 cells, their attachment to laminin-2/4 beads is 5 times higher than that to laminin-1-beads after a 1 min incubation, but as early as after 5 min this distinction disappeared, owing to bead internalization. The presence of a specific receptor to laminin-2/4 but not to laminin-1 on the keratinocyte surface has been suggested. Keratin differences in cytoskeleton organization in normal and transformed skin cells spread on the substrates covered with laminin-1 and laminin-2/4 were demonstrated.

[Various effects of laminin-1 and laminin-2/4 on adhesion and migration of cultured human keratinocytes]. / Razlichnoe vliianie laminina-1 i laminina-2/4 na adgeziiu i migratsiiu kul'tiviruemykh keratinotsitov cheloveka.

The cell-matrix interaction is one of the factors defining the cell behavior in normal and wounded tissues. To determine the function of laminin-2/4, one of components of the skin basement membrane in the process of reepithelization, we studied its interaction with human keratinocytes. The adhesive properties of laminin-2/4 and its effect on keratinocytes migration in vitro were analysed. For comparison with our present investigation, we used the earlier studied laminin-1 from EHS mouse sarcoma. Laminin-2/4 appeared to be a good substrate for human keratinocytes, and this correlates with a greater number of cell surface receptors compared with laminin-1. Laminin-2/4 alone does not stimulate keratinocyte migration, but, in contrast to laminin-1, supports EGF-mediated migration. The obtained results give an insight into the function of laminin-2/4 in normal skin and during wound healing.

[Effects of extracellular matrix elements on pseudopodial activity of rat keratinocytes]. / Vliianie élementov vnekletochnogo matriksa na psevdopodial'nuiu aktivnost' keratinotsitov krys.

Effects of extracellular matrix elements on the migration activity of keratinocytes have been studied in the primary culture obtained from newborn rats. Collagen of type I, matrigel, its fractions and the matrix produced by fibroblasts were used as substrata for cultivation. A method of migration activity estimation using latex spheres 0.8 mkm in diameter was first used. We have revealed that keratinocytes from the primary culture do not migrate on matrigel and fibroblast matrix, though displaying some pseudopodial activity. This activity dramatically increases on type I collagen, and a weak migration ability appears correlating with a particular structure of the actin cytoskeleton, i.e. with the appearance of special lamellopodia-connected filopodia.

[The stripping of cultures of rat keratinocytes]. / Stripping kul'tur keratinotsitov krys.

To develop a stripping model for newborn rat keratinocytes we chose appropriate culture conditions. As it has been shown for human keratinocytes, this model allows to separate the suprabasal cells from the basal cell layer, to obtain a pure population of basal-like cells. One of possible applications of this method was demonstrated in the study on the influence of extracellular matrix components on keratinocyte proliferation. A fraction of basal membrane gel, "the matrigel", was shown to decrease the uptake of 3H-thymidine by keratinocytes in the stripping model.

[The effect of the components of the extracellular matrix on the spreading of rat keratinocytes in the substrate during cultivation in a low-calcium medium]. / Vliianie komponentov vnekletochnogo matriksa na rasplastyvanie keratinotsitov krysy na substrate pri kul'tivirovanii v nizkokal'tsievoi srede.

Two-day-old newborn rat keratinocytes were plated in serum-free low-Ca medium on different substrates. The culture conditions prevented from keratinocyte aggregation, and therefore allowed to observe the interaction between a single cell and the substrate without interference of cell-cell contacts. It is shown that separate cells spread on type I collagen, whereas cell colonies developed on fibronectin and non-treated glasses. Cellular actin distribution, revealed by rhodamine-phalloidin staining, suggested that on type I collagen cell-substrate interactions differed from those on other substrates. While cells on type I collagen had large radial phillopodia with rich actin staining, they had marginal actin rings and small phillopodia plated on fibronectin or glass. Taking together differences in cytoskeletal actin distribution and shapes of colonies type I collagen is supposed to be more powerful than fibronectin and glass in binding the corresponding cell receptors, thus preventing from colony formation.