REGULATION OF THE CELL-DIFFERENTIATION AT THE BASEMENT-MEMBRANE LEVEL- THE INTESTINAL EPITHELIUM AS AN EXAMPLE

The basement membrane (BM) separates tissue compartments from each oth er, e,g, epithelial elements from the surrounding stroma, Recently, th e dynamic role of BM in regulation of epithelial cell differentiation as well as their organization into three-dimensional tissues has becom e better understood, The molecular constituents of BM are produced by the interplay of epithelial and mesenchymal cells, BM molecules includ e type IV collagen, laminin (Ln), nidogen, proteoglycans and various o ther proteins. Both type IV collagen and Ln are important in forming a core filament network, whereas the function of different Ln isoforms is additionally directed to epithelial cell polarization and different iation. Un isoforms are differentially distributed, accompanying the e pithelial cell differentiation and function as is well exemplified in the intestinal epithelium. The role of Ln in enterocyte differentiatio n has also been shown in experimental cell culture studies.