Wnt-7a up-regulates matrix metalloproteinase-12 expression and promotes cell proliferation in corneal epithelial cells during wound healing

Corneal wound repair involves the rapid coverage of a denuded area by residual epithelial cells. During wound healing, there are different cell behaviors in different regions of the epithelium: cell proliferation in the peripheral epithelium and cell migration in the central epithelium. We found that Wnt-7a was rapidly induced in the wounded cornea, promoted the proliferation of corneal epithelial cells, and enhanced wound closure. Matrix metalloproteinase-12 (MMP-12) was detected in the peripheral epithelium, where cell proliferation was enhanced, but was diminished in the migrating central epithelium. Wnt-7a induced the accumulation of b-catenin and the activation of Rac and b-catenin, and Rac synergistically induced the transcription of MMP-12. Blocking the function of MMP-12 delayed wound closure induced by Wnt-7a. Our results also suggest that, in addition to the b-catenin pathway, Wnt-7a might induce a b-catenin-independent pathway. By regulating the proliferation of corneal epithelial cells, Wnt-7a and MMP-12 appear to contribute to corneal wound healing.