Matrix metalloproteinase secretion is stimulated by TGF-β in cultured lens epithelial cells

Purpose. To determine if TGF-β regulates the expression of metalloproteinases in chick lens annular pad cells. Methods. The activity of secreted matrix metalloproteinases was examined with gelatin zymography in primary cultures exposed to TGF-β. Results. Metalloproteinases with electrophoretic mobilities corresponding to MMP2 and MMP9 were tentatively identified. Activated, processed forms of the two metalloproteinases were also observed. Plasminogen activators potentially capable of initiating metalloproteinase cascades were concomitantly elicited. Metalloproteinase secretion was shown to be specific for TGF-β stimulation and independent of substrate composition. Conclusions. These results indicate that TGF-β-mediated processes could be responsible for localized lens capsular heterogeneity, establishing a substrate suitable for cell migration or the release of matrix-bound factors which influence the terminal differentiation of lens cells.