CHANGES IN BETA-4 INTEGRIN EXPRESSION AND LOCALIZATION IN-VIVO IN RESPONSE TO CORNEAL EPITHELIAL INJURY

Purpose. To determine whether production and localization of beta(4) i ntegrin is altered during in vivo corneal epithelial cell migration in response to debridement wounding. Methods. Rat corneas were wounded a nd animals were killed at times ranging from 3 hours to 14 days. At va rious time points, corneal epithelial integrins were quantitated by ge l electrophoresis and immunoblotting of epithelial extracts and then w ere localized by immunohistochemistry. Results. As early as 6 hours af ter wounding, an increase in the amount of the beta(4) integrin subuni t expressed per microgram of total protein was observed. The level of beta(4) continued to increase until wound closure. By 14 days after wo unding, beta(4) expression returned to control levels. The level of ex pression of beta(1) and alpha(v) integrins were found not to change si gnificantly throughout migration. Immunohistochemical analyses using a ntibodies against either the beta(4) integrin subunit or HD1, a hemide smosomal plaque component, showed that in control sections, beta(4) in tegrin and HD1 codistributed in a linear staining pattern above the ba sement membrane. As early as 4 hours after wounding, beta(4) was prese nt in both basal and suprabasal epithelial cells, and HD1 was retained at the basal aspect of the epithelial basal cells. Conclusions. These data show that changes in expression and localization of beta(4) inte grin occur in the corneal epithelium in response to debridement woundi ng in vivo. Previously, we had shown that quantitative changes in beta (4) integrin expression do not occur in an in vitro organ culture mode l used for the study of corneal epithelial cell migration. Increased b eta(4) expression may not be required for migration per se, but it may be play a role in either stabilizing cell:cell or cell:substrate adhe sion in vivo or in preparing cells to undergo mitosis during restratif ication.