Role of the small GTP-binding protein rho in epithelial cell migration in the rabbit cornea.

PURPOSE To determine the role of the small guanosine triphosphate (GTP)-binding protein Rho in the migration of corneal epithelial cells. METHODS The presence of the Rho target proteins Rho-associated coiled coil-containing protein kinase (ROCK)-1 and ROCK-2 in rabbit cornea was examined by immunohistochemical analysis, and that of the corresponding mRNAs in rabbit corneal epithelial cells was determined by reverse transcription-polymerase chain reaction analysis. The effects of various agents on epithelial cell migration were investigated by measuring the length of the migration path in rabbit corneal blocks in culture. RESULTS Both ROCK-1 and ROCK-2 were detected in the rabbit corneal epithelium at both protein and mRNA levels. The Rho activator lysophosphatidic acid (LPA) stimulated corneal epithelial migration in a dose-dependent manner, whereas exoenzyme C3, a Rho inhibitor, inhibited epithelial migration also in a dose-dependent manner. The stimulatory effect of LPA on corneal epithelial migration was prevented by exoenzyme C3. Both cytochalasin B, an inhibitor of actin filament assembly, and ML-7, an inhibitor of myosin light chain kinase, also prevented LPA stimulation of epithelial migration. CONCLUSIONS These results suggest that Rho mediates corneal epithelial migration in response to external stimuli by regulating the organization of the actin cytoskeleton.