Differentiated intestinal epithelial cells exhibit increased migration through polyamines and myosin II

Early mucosal restitution is a rapid process by which differentiated intest inal epithelial cells migrate to reseal superficial wounds. However, most o f the in vitro studies for restitution employ undifferentiated intestinal c rypt cells as a model. The transcription factor, Cdx2, plays an important r ole in the regulation of intestinal epithelial differentiation. Forced expr ession of the Cdx2 gene in undifferentiated intestinal crypt cells induces the development of a differentiated phenotype. The current study was design ed to determine changes in differentiated intestinal epithelial cell migrat ion after wounding in the stable Cdx2-transfected IEC-B cells and then to e xamine involvement of polyamines and nonmuscle myosin Il in the process of cell motility. Cdx2-transfected IEC-B cells were associated with a highly d ifferentiated phenotype and exhibited increased cell migration after woundi ng. Migration of Cdx2-transfected IEC-6 cells were approximately four times that of nontransfected IEC-6 cells. Migration after wounding was associate d with significant increases in polyamine synthesis. Depletion of cellular polyamines by 5 mM alpha-difluoromethylornithine (DFMO), a specific inhibit or of polyamine biosynthesis, inhibited cell migration without affecting th e differentiated phenotype. DFMO also decreased levels of nonmuscle myosin II mRNA and protein and resulted in reorganization of myosin II, along with a marked reduction in stress fibers. Exogenous spermidine given together w ith DFMO not only returned nonmuscle myosin II levels and cellular distribu tion toward normal but also restored cell migration to control levels. Thes e results indicate that 1) Cdx2-transfected IEC-B cells exhibit increased c ell migration after wounding and 2) cellular polyamines are absolutely requ ired for stimulation of cell migration in association with their ability to modulate the structural organization of nonmuscle myosin Ii.