Selective changes in protein kinase C (PKC) isoform expression in rabbit corneal epithelium during wound healing. Inhibition of corneal epithelial repair by PKC alpha antisense

Protein kinase C (PKC) isoforms display different sensitivities to modulato rs, tissue specificities and subcellular localizations. PKC alpha increases during rabbit corneal epithelial wound healing. Here we report differentia l expression of PKC isoforms in the cornea of rabbits at 1, 2, 4 and 8 days during reepithelization. Cytosolic, membrane and detergent-insoluble fract ions from epithelium were analysed by Western blot using monoclonal antibod ies against the different PKC isoforms. We have identified PKCa, gamma, eps ilon, mu and iota. PKC alpha and gamma were expressed only in the cytosolic fraction, with the expression of PKCa markedly increasing 4 days after inj ury. Corneas cultured in the presence of rabbit-specific PKC alpha antisens e showed a greater than 50% inhibition of wound closure, compared to contro ls. The PKC epsilon and mu were expressed in the soluble, as well as in the membrane fraction. Additionally, 12% of PKC mu was found attached to the d etergent insoluble fraction. The expression of the membrane-bound PKC epsil on and mu isoforms decreased between 1 and 2 days following injury. Only 10 % of the PKC iota expressed in corneal epithelium was membrane bound, but b etween 4 and 8 days after de-epithelization, the expression in this fractio n increased three-fold. Our results suggest that changes in the expression and distribution within the various fractions of selective isoforms of PKC after injury could be involved in events leading to wound healing and that PKCa is a key modulator in rabbit corneal wound repair. (C) 1998 Academic P ress.