Figure 4. Cataract-related apoptosis is blocked if Src kinase activation is suppressed

Lenses were grown in cataract culture conditions in the presence (PP1) and absence (vehicle, DMSO) of the Src kinase inhibitor PP1 and analyzed for DEVDase activity (A). A greater than three-fold increase in activation of caspase 3-like proteases was induced in the epithelium of lenses grown in cataract culture. Activation of the mitochondrial death pathway was blocked by suppressing the Src kinase activity in the cataract cultures. TUNEL staining (B) was performed to analyze the extent of apoptosis in the epithelium of lenses grown for 10 days in cataract culture in the presence (bottom panels) and absence (top panels) of the Src kinase inhibitor PP1. The panels on the left provide low power DAPI stained (nuclei) images of the sections examined on the right by TUNEL assay with the area imaged indicated by a white box. Co-localization of nuclei (DAPI, blue) and TUNEL staining (green) are presented side-by-side on the right. These studies show extensive apoptosis of cells in the lens epithelia of cataractous lenses at culture day 10 and that lens epithelial cell survival is protected by suppression of Src kinase activity.