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Figure 5. SI-mediated oxidative stress in iPSC-RPE after 72 h treatment. iPSC-RPE cell lines were treated daily with fresh 0.125 or 0.25 mM SI for a total of 72 h, cells incubated in medium without SI served as a control. mRNA expression of HMOX1 (A) and NQO1 (B) was determined via quantitative reverse transcriptase polymerase chain reaction after normalization to HPRT1 and calibration against the control (ctrl). While SI treatment significantly upregulated both NQO1 and HMOX1 expression, no differences in the NRF2 mediated stress response could be observed between HR and LR lines. Western blot analyses using antibodies against HMOX1 and NQO1 (C, D). Signal intensities were normalized against ACTB as a loading control and calibrated against the untreated control. Data are presented as means + SD [n = 3 for (A, B) and n = 4 for (C, D)] for left panels showing individual cell lines, while n = 4 for comparison between HR and LR; *P < 0.05, Mann-Whitney U-test. SI: Sodium iodate; iPSC: induced pluripotent stem cell; RPE: retinal pigment epithelium; HR: high-risk; LR: low-risk.