Differential effects of transforming growth factors on localization of adhesion complex proteins following corneal epithelial cell wounding

Abstract

PURPOSE. The differential effects of transforming growth factor (TGF) alpha, beta1 and beta2 on the de novo localization of heparan sulfate proteoglycan, collagen type VII and laminin-1 to the adhesion complex were analyzed using an in vitro model of corneal epithelial cell wound healing. METHODS. Bovine corneal explants were maintained in culture media containing either no growth factor or 1, 5, or 10 ng/ml TGFalpha, TGFbeta1 or TGFbeta2. After 24 or 48 hours in culture, cryostat sections of explants were processed for immuno-fluorescence microscopy using antibodies directed against heparan sulfate proteoglycan, collagen type VII or laminin-1. RESULTS. A comparison of antibody labeling patterns and relative fluorescence intensity of antibody labeling to controls suggested that TGFalpha inhibits the spatial polarization of proteins into the reforming adhesion complex during early stages of wound healing. Both TGFbeta1 and beta2 enhanced the linear localization of the three proteins to the site of the reforming adhesion complex. However, in our model TGFbeta isoforms did not have identical functions. TGFbeta2 accelerated the temporal localization of collagen type VII to the adhesion complex, an effect which was not observed with TGFbeta1. CONCLUSIONS. TGFbeta, but not TGFalpha, may play an important role in corneal epithelial cell wound healing by accelerating the reformation of the adhesion complex and subsequent epithelial cell-extracellular matrix adhesion.