Protein kinase C activation during corneal endothelial wound repair.

In previous studies, the authors have shown that the two forms of cell translocation that occur during corneal endothelial monolayer wound repair can be pharmacologically separated. Epidermal growth factor (EGF) enhanced the breaking of cell-cell contacts and movement of individual cells from the wound edge, while indomethacin, an inhibitor of PGE2 synthesis, promoted cell enlargement and spreading of the confluent monolayer sheet into the wound defect. From these findings, the authors hypothesized that the two forms of cell translocation were stimulated by different but coordinately regulated second messenger systems. The current studies used selected protein kinase C (PKC) stimulators and inhibitors, Rh-phalloidin staining of actin filaments, and immunofluorescent localization of PKC to show that: (1) PKC acts as a mediator of the EGF-induced enhancement of the migratory response; (2) the enhanced migratory response results, at least in part, from short-term EGF stimulation of PKC; (3) PKC is a mediator of the EGF-induced alterations in the actin cytoskeleton; and (4) PKC becomes activated in cells at the wound edge during normal, endogenously stimulated wound repair. The results of these studies provide suggestive evidence that wounding of the corneal endothelial monolayer must produce an endogenous, EGF-like stimulation of PKC activity in cells at the wound edge. One effect of PKC activation that must contribute to stimulation of individual cell migration is the induction of cytoplasmic changes that lead to alterations in actin filament organization.