Cdx1 promotes differentiation in a rat intestinal epithelial cell line

Background & Aims: Homeobox genes are involved in establishing and maintain ing differentiated patterns in adult tissues, Cdx1 might carry out that fun ction in the intestinal epithelium because its expression is specific to th at tissue and increases during development. Methods: Cdx1 expression was in duced in IEC-6 intestinal epithelial cells by stable transfection, and subs equent changes in cell growth, resistance to apoptosis, migration, and diff erentiation were monitored. Results: Compared with control, IEC-6/Cdx1 cell s proliferated more rapidly, were more resistant to apoptosis, and migrated 3-4 times faster, as shown by an in vitro wound assay, IEC-6/Cdx1 cells in culture formed multilayers. Morphology of the top layer was similar to tha t of columnar epithelium, with cells showing typical features of differenti ated enterocytes, including complex junctions and well-developed microvilli with glycocalix, Expression of 2 markers of enterocyte differentiation, am inopeptidase N and villin, was induced in IEC-6/Cdx1 cells, Aminopeptidase N was targeted to the basolateral membrane, and villin was localized to the cytoplasm, Actin filaments, which were mostly present in transcytoplasmic stress fibers in control cells, were redistributed to the cortex in Cdx1-tr ansfected cells, Conclusions: Cdx1 expression in IEC-6 cells induces phenot ypic changes characteristic of differentiating enterocytes, suggesting an i mportant role for Cdx1 in the transition from stem cells to proliferating/t ransit cells.