The effect of fibronectin on cytoskeleton structure and transepithelial resistance of alveolar type II cells in primary culture.
The cytoskeleton of alveolar type II cells on different matrices has been examined, and the bioelectric properties of these cells grown as monolayers in primary culture has be measured using Ussing-type chambers, to determine whether the extracellular matrix affects the cytoskeletal organization of alveolar type II cells and whether any such interactions influence their physiological functions. Alveolar type II cells cultured on a fibronectin substratum spread slowly over a 6-day period to produce cells of extremely large diameter. The cytoskeletal structure of these cells was characterized by a more marked accumulation of large bundles of actin and a finer network of keratin than cells grown on a collagen substratum. The transepithelial resistances of monolayers grown on a fibronectin substratum were much higher than those on a collagen substratum. These results indicate that alveolar type II cells cultured on fibronectin can form tighter, better organized and more polarized monolayers in primary culture, which suggests that fibronectin may have a physiologically important role in the maintenance of the alveolar wall.