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D.W. Li, J.–P. Liu, P.C. Schmid, R. Schlosser, H. Feng; Protein Phosphatase–1 Promotes Survival of Lens Epithelial Cells through Dephosphorylation of the Tumor Suppressor, p53. . Invest. Ophthalmol. Vis. Sci. 2004;45(13):401.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Our previous studies have revealed that protein phosphatase–1 is important for survival of lens epithelial cells. With differential sensitivity of PP–1 and PP–2A to okadaic acid, we have previously shown that inhibition of protein phosphatase–1 but not –2A induces apoptosis of both rat and rabbit lens epithelial cells. In the present study, we have explored the mechanism by which PP–1 promotes survival of lens epithelial cells. Methods: The function of p53 in mediating apoptosis was analyzed with RNAi. The phosphorylation status of p53 was analyzed with Western blot analysis. The dephosphorylation of p53 by protein phosphatase–1 was explored with co–immunoprecipitation, and in vitro and in vivo dephosphorylation assays. Results: Knockout of p53 expression in human lens epithelial cells by RNAi led to substantial inhibition of okadaic acid and calyculin A–induced apoptosis. PP–1 is involved in dephosphorylation of multiple sites of p53. Dephosphorylation of p53 by PP–1 attenuates the apoptotic function of p53. Conclusions: Part of the mechanism by which Protein phosphatase–1 promotes survival of lens epithelial cells is derived from its dephosphorylation of p53. Supported by the Hormel Foundation, University of Minnesota Graduate School and Lotus Scholar Professorship funds from Hunan Normal University.None.
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