REGULATION OF CELL-CELL ADHESION OF MDCK CELLS BY CDC42 AND RAC1 SMALL GTPASES

Rad, a member of the Rho small GTPases family, has recently been shown to be involved in the regulation of cell-cell adhesion mediated by ca dherin. Here we showed that Cdc42, another member of Rho family, accum ulated at cell-cell contact sites. Microinjection of Rho GDI, a negati ve regulator of the Rho family members, into Madin-Darby canine kidney (MDCK) cells resulted in perturbation of epithelial cell. morphology and of cell-cell and cell-substratum adhesions, and comicroinjection o f dominant active Cdc42 or Rad reversed the action of Rho GDI, suggest ing that the active form of Cdc42 or Rad is required for maintaining t he cell-cell and cell-substratum adhesions. These observations suggest that Cdc42, in addition to Rad, can regulate the cell-cell adhesion. (C) 1997 Academic Press.