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L. Estlack, M. L. Denton, M. S. Foltz, K. J. Schuster, R. J. Thomas; Adaptive Response of RPE Cells to Superoxide Dismutase 2 Deficiency Protects Against Photochemical Lethality. Invest. Ophthalmol. Vis. Sci. 2008;49(13):5911.
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© ARVO (1962-2015); The Authors (2016-present)
Identify possible roles for superoxide dismutase 1 (SOD1) and SOD2 in photooxidative damage mechanisms at 413 nm.
Using cultured RPE cells isolated from a wild type mouse, an SOD1 deficient or an SOD2 deficient mouse, threshold irradiances for photochemical damage from a laser were determined and compared with our hTERT-RPE1 model. The cultured cells were artificially pigmented using isolated bovine melanosomes as described elsewhere (ref) and exposed to a range of laser (413 nm, 0.3 mm, 100 s, flat-top profile) irradiances and assayed for cytotoxicity (fluorescent staining with calcein AM and ethidium homodimer1). Western blot and immunohistochemistry were used to ensure SOD deficiency.
Western blot analysis showed that the SOD deficient cells had 40-60 % reductions in their respective proteins. Immunohistochemistry showed that the cells of each group had the appropriate intracellular localization of SOD1 and SOD2, however this method could not distinguish a significant difference in SOD protein levels. The wild type and SOD1 deficient cells were found to have identical laser damage thresholds as the human cells. In contrast, the SOD2 deficient cells had a 2-fold increase in threshold value over the other sample types, indicating a reduced sensitivity to photochemical (413 nm) damage.
Neither SOD1 and SOD2 play a direct role in the photochemical damage mechanism at 413 nm. In the process of adapting to the SOD2 deficiency, RPE cells can have a metabolic shift, which in turn provides protection against significant photo-oxidative damage.
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