Extracellular matrix proteins in small-intestinal cell cultures.

Intestinal cell cultures offer unique possibilities to study the effect of extracellular matrix components on epithelial proliferation and differentiation. We have investigated the specific affinity for distinct matrix proteins, including laminin, collagen types I, III, and IV, and fibronectin, versus neutral control proteins in various small-intestine epithelial cell cultures. Both primary cells and intestinal epithelial cell lines display enhanced affinity for basement membrane constituents compared with interstitial collagens. Only the very undifferentiated, proliferative intestinal epithelial cells also synthesize these proteins, as determined by immunofluorescence and radioimmunoassay. On polarization and maturation, biosynthesis of basement membrane proteins is markedly reduced. Differentiation of intestinal epithelial cells is promoted only by laminin. Fibronectin and collagen type IV have no effect. Putative cell membrane receptors for individual basement membrane proteins are discussed.