Protein phosphorylation and dephosphorylation play important roles in regulating cell signalling, proliferation, differentiation and apoptosis. In our previous studies, we have demonstrated that stress-induced lens epithelial cell apoptosis is a very important early event during stressinduced non-congenital cataract formation by various stress factors. In the present study, we have examined the distribution of the activity of protein phosphatase-1 and 2A in human, bovine and rat lenses and their function in regulating cell death in rabbit lens epithelial cells. Our results reveal that majority of the phosphatase activity (both PP-1 and PP-2A) is localized in the epithelial cells of all three different lenses. In the lens fiber cells, only cortex fibers immediately underlying the lens epithelial cell layer have some PP-1 and PP-2A activity. Other fiber sections essentially display no phosphatase activity. In the rabbit lens epithelial cells, inhibition of PP-2A has no effect on cell viability. In contrast, inhibition of PP-1 induces rapid lens epithelial cell apoptosis. This induced cell death is associated with up-regulation of p53 and box and can be inhibited by blocking protein synthesis. Our results suggest that PP-1 is an important signalling component regulating apoptosis in lens system. (Supported by a NIH grant EY 11372 to D. W-C. Li and Research to Prevent Blindness).
|Original language||English (US)|
|State||Published - Dec 1 1998|
ASJC Scopus subject areas
- Molecular Biology