Coordinated reassembly of the basement membrane and junctional proteins during corneal epithelial wound healing.

PURPOSE: To characterize changes in the localizations of the basement membrane protein laminin-1 and of adhesion proteins of intercellular junctions during wound healing after epithelial ablation in the rat cornea.
METHODS: Epithelial ablation was performed with an excimer laser. Rats were killed immediately, 12 hours, 24 hours, 3 days, or 4 weeks after ablation, and corneal cryosections were subjected to two-color immunofluorescence staining with antibodies to laminin-1 and antibodies to connexin43 for gap junctions, desmoglein 1 or 2 (desmoglein 1 + 2) for desmosomes, or E-cadherin for adherens junctions. Sections were also stained with antibodies to occludin for examination of tight junctions.
RESULTS: Laminin-1 was detected in the basement membrane, connexin43 in the basal cell layer, desmoglein 1 + 2 in the wing cell layer, E-cadherin in all cell layers, and occludin in the wing and superficial cell layers of the intact corneal epithelium. Laminin-1 immunostaining was not detected at the leading edge of migrating epithelial cells until 24 hours after ablation. Expression of connexin43 and desmoglein 1 + 2 coincided with the reappearance of laminin-1, whereas that of E-cadherin and occludin was apparent regardless of the absence or presence of laminin-1. Epithelial remodeling was complete after 4 weeks. The basement membrane was re-established, and the expression patterns for all the adhesion proteins were identical with those characteristic of the intact cornea.
CONCLUSIONS: Actively migrating epithelial cells no longer manifested gap junctions and desmosomes in the wounded area with no basement membrane. Re-establishment of the basement membrane coincided with reassembly of these intercellular junctions, suggesting that the presence of the basement membrane may be required for their reformation in the rat cornea.