Identification and distribution of 14.3.3sigma (stratifin) in the human cornea.

We demonstrate for the first time the expression of 14.3.3sigma, an epithelial cell differentiation marker, in human corneal epithelium. 14.3.3sigma appeared at 30 kDa, pI 4-5, in 2D gels of corneal extracts. We found no significant differences in 14.3.3sigma levels between healthy corneas and corneas from keratoconus, corneal dystrophy, and corneal edema patients. 14.3.3sigma immunofluorescence was observed in the cytoplasm and nucleus of epithelial cells and colocalized with cyclin-B1. 14.3.3sigma was secreted by HCE-2 cells; HCE-2-conditioned medium induced matrix metalloproteinase-1 in cultured keratocytes. In summary, our work presents evidence of 14.3.3sigma expression in corneal epithelium and elaborates over its possible implications in corneal pathologic conditions.