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C. Hutnik, H. Liu, A. Mao, T. Peng; Regulation Of Retinal Pigment Epithelial Cell Death Induced By Oxidative Stress . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2074.
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To investigate the regulation of RPE cell death induced by oxidative stress. Specifically, the role of p38 Mitogen–Activated Protein Kinase (MAPK) in oxidative stress–induced RPE cell death was examined.
Oxidative stress was induced by the chemical oxidant tert–butylhydroperoxide (t–BOOH) in the human RPE cell line ARPE–19. Cell viability was assessed by both the MTT assay and the trypan blue assay. The phosphorylation of p38 MAPK was measured by Western blot using a specific antibody against phospho–p38 MAPK. Knockdown and activation of p38 MAPK were carried out by siRNA and over–expression of MAPK kinase–6E (MKK6E), respectively.
t–BOOH induced RPE cell death in a dose– and time–dependent manner. t–BOOH increased phosphorylation of p38 MAPK. Both inhibition of p38 MAPK with a selective inhibitor SB203580 and knockdown of p38 MAPK with siRNA enhanced t–BOOH induced RPE cell death. Over–expression of a dominant active mutant of MKK6 (MKK6E), a kinase upstream of p38 MAPK, increased phosphorylation of p38 MAPK and attenuated t–BOOH–induced RPE cell death. Additionally, preconditioning with a low dose of t–BOOH, which increased p38 MAPK activation but did not induce appreciable cell death, decreased the RPE cell death induced by a higher dose of t–BOOH. This protective effect was absent when the RPE cells were pre–treated with SB203580 for 30 minutes prior to preconditioning.
Activation of p38 MAPK protects human RPE cells against oxidative–induced injury. Since RPE cells play a key role in the homeostasis of the retina, this finding may have significant implications of retinal ganglion cell and photoreceptor health.
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