PERTURBATION OF CELL-ADHESION AND MICROVILLI FORMATION BY ANTISENSE OLIGONUCLEOTIDES TO ERM FAMILY MEMBERS

To examine the functions of ERM family members (ezrin, radixin, and mo esin), mouse epithelial cells (MTD-1A cells) and thymoma cells (L5178Y ), which coexpress all of them, were cultured in the presence of antis ense phosphorothioate oligonucleotides (PONs) complementary to ERM seq uences. Immunoblotting revealed that the antisense PONs selectively su ppressed the expression of each member. Immunofluorescence microscopy of these ezrin, radixin, or moesin ''single-suppressed'' MTD-1A cells revealed that the ERM family members are colocalized at cell-cell adhe sion sites, microvilli, and cleavage furrows, where actin filaments ar e densely associated with plasma membranes. The ezrin/radixin/moesin a ntisense PONs mixture induced the destruction of both cell-cell and ce ll-substrate adhesion, as well as the disappearance of microvilli. Ezr in or radixin antisense PONs individually affected the initial step of the formation of both cell-cell and cell-substrate adhesion, but did not affect the microvilli structures. In sharp contrast, moesin antise nse PONs did not singly affect cell-cell and cell-substrate adhesion, whereas it partly affected the microvilli structures. These data indic ate that ezrin and radixin can be functionally substituted, that moesi n has some synergetic functional interaction with ezrin and radixin, a nd that these ERM family members are involved in cell-cell and cell-su bstrate adhesion, as well as microvilli formation.