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L. Gong, J. Liu, M. Deng, D. Yuan, Q. Yan, H.-G. Chen, D. W. Li; Oxidative Stress Regulates Both Protein Kinases and Protein Phosphatase to Initiate Apoptosis of Retinal Pigment Epithelial Cells. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5927.
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© ARVO (1962-2015); The Authors (2016-present)
Oxidative stress is one of the major stress factors causing different human diseases including retinal diseases. In the present study, we have explored the effects of the oxidative stress on both kinases and phosphatases in retinal pigment epithelial cells (ARPE-19) with the goal to understand the possible signaling pathways mediating retinal diseases.
ARPE-19 cells were cultured in MEM in the presence of 10% serum. Stable hydrogen peroxide system was developed and maintained in the culture media. After treatment by physiological level of hydrogen peroxide, the mock and treated cells were harvested for analysis of kinase and phosphatase expression and activation. Apoptosis induced by oxidative stress was examined with electron microscopy and hoechst staining.
Under treatment of a constant level of 90 uM hydrogen peroxide, the three types of MAPKs are activated very quickly in the ARPE-19 cells. In contrast, the protein serine/threonine phosphtases-1 and -2A are downregulated and inactivated gradually. Associated with activation of MAPKs and inactivation of PP-1 and PP-2A, p53, the master regulator of apoptosis, becomes hyperphosphorylated at Ser-15 residue and its transactivity becomes enhanced. As a result, the intrinsic apoptotic death pathway is activated to mediate apoptosis. In addition, caspase-8 and caspase-2 mediated death pathways seem to be activated, too.
Oxidative stress regulates multiple signaling pathways to initiate apoptosis of RPE cells, which likely contributes to the pathological processes of retinal degradation.
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