Coordinated Reassembly of the Basement Membrane and Junctional Proteins during Corneal Epithelial Wound Healing

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. 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. 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. 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.