THE EXPRESSION OF INTEGRIN SUBUNITS ALPHA-6 AND BETA-4 BY CORNEAL EPITHELIAL-CELLS ON MODIFIED HYDROGEL SURFACES

Our goal was to quantitate the expression and localization of integrin subunits alpha 6 and beta 4 by corneal epithelial cells on defined sy nthetic substrates. Previously we demonstrated that the cytoplasmic pH and translocation of the alpha 6 integrin subunit to the cell membran e was modified by ionic interactions. These results suggest that chang es in the ionic interactions at the cell-substrate interface not only alter the intracellular milieu but ultimately affect the expression of adhesion proteins. To test this hypothesis, hydroxyethylmethacrylate (hema) hydrogels were modified by the addition of amines (N,N-dimethyl aminoethylmethacrylate) or carboxyl moieties (methacrylic acid). Chang es in the distribution of mRNA and protein were monitored using confoc al laser scanning microscopy. The steady state level of integrin mRNA was evaluated, and the results indicate that while the plating efficie ncy was identical on all surfaces, the expression and localization of integrin subunits was surface dependent. Alpha6 and beta 4 proteins we re localized along the basal surface of nonpermeabilized cells culture d on laminin, on surfaces with amine moieties, and on those with amine and carboxyl moieties. The level of diffuse cytoplasmic staining incr eased with the presence of carboxyl moieties. Alpha6 and beta 4 integr in subunits were negligible when the surfaces contained carboxyl moiet ies alone. The expression of alpha 6 and beta 4 mRNA was higher on sur faces containing amine moieties than on surfaces containing only carbo xyl moieties. These results indicate that the characteristics of the s ubstrate and the resulting cell-matrix interaction alter protein and m RNA expression of integrin subunits. (C) 1997 John Wiley & Sons, Inc.