CYTOKERATIN EXPRESSION IN EPITHELIAL-CELLS ISOLATED FROM THE CRYPT AND VILLUS REGIONS OF THE RODENT SMALL-INTESTINE

Many physiological and structural features of epithelium in the Small intestine are regulated during their transit from the crypt base to th e villus tip. This crypt-villus axis is an important model for the stu dy of the regulation of cell proliferation and differentiation. We hav e investigated the expression of cytokeratins in purified epithelial c ells from the proliferative (crypt) and differentiated (villus) region s of this tissue. Three polypeptides were identified (cytokeratins 8, 18 and 19) as well as a fourth, 46 kDa polypeptide with similar electr ophoretic characteristics to the recently identified cytokeratin 20. T he distribution of these molecules was found to vary along the crypt-v illus axis, with cytokeratin 18 being restricted to the proliferative crypt and cytokeratins 8 and 19 demonstrating more uniform distributio ns. The 46 kDa component was found to be expressed predominantly withi n the villus epithelium. Although there is no substantial evidence of a direct role for cytokeratins in the process of epithelial differenti ation, these data suggest that differential expression of cytokeratins is associated with changes in intestinal epithelial differentiation.