EZRIN IS AN EFFECTOR OF HEPATOCYTE GROWTH FACTOR-MEDIATED MIGRATION AND MORPHOGENESIS IN EPITHELIAL-CELLS

The dissociation, migration, and remodeling of epithelial monolayers i nduced by hepatocyte growth factor (HGF) entail modifications in cell adhesion and in the actin cytoskeleton through unknown mechanisms. Her e we report that ezrin, a membrane-cytoskeleton linker, is crucial to HGF-mediated morphogenesis in a polarized kidney-derived epithelial ce ll line, LLC-PK1. Ezrin is a substrate for the tyrosine kinase HGF rec eptor both in vitro and in vivo. HGF stimulation causes enrichment of ezrin recovered in the detergent-insoluble cytoskeleton fraction. Over production of wild-type ezrin, by stable transfection in LLC-PK1 cells : enhances cell migration and tubulogenesis induced by HGF stimulation . Overproduction of a truncated variant of ezrin causes mislocalizatio n of endogenous ezrin from microvilli into lateral surfaces. This is c oncomitant with altered cell shape, characterized by loss of microvill i and cell flattening. Moreover, the truncated variant of ezrin impair s the morphogenic and motogenic response to HGF, thus suggesting a dom inant-negative mechanism of action. Site-directed mutagenesis of ezrin codons Y145 and Y353 to phenylalanine does not affect the localizatio n of ezrin at microvilli, but perturbs the motogenic and morphogenic r esponses to HGF, These results provide evidence that ezrin displays ac tivities that can control cell shape and signaling.