Gene expression analysis of an H2O2-resistant lens epithelial cell line

Gene expression patterns were examined in lens epithelial cells conditioned to grow in 125 μM hydrogen peroxide in order to define the protective mechanisms that may be involved in survival during oxidative stress. RNA was extracted from normal and hydrogen peroxide-resistant αTN4 mouse lens epithelial cells. Gene expression was evaluated using Differential Display (DD) and RT-PCR. Upregulation of mRNAs for antioxidant and cellular defense enzymes was observed. The highest elevation detected was a 14-fold increase in catalase in the hydrogen peroxide-resistant cells. Glutathione peroxidase, ferritin, and αB-crystallin were upregulated 2-fold, and reticulocalbin was upregulated 6-fold in the resistant cells. αA-crystallin was downregulated 5-fold, while aldose reductase and mitochondrial gene products were unchanged. Thus, in the αTN4 mouse lens cell line, long-term exposure to high levels of hydrogen peroxide elicited an upregulation of transcripts for enzymes involved in hydrogen peroxide degradation, metal binding, and chaperone function. Since mitochondrial gene transcription is sensitive to hydrogen peroxide, the presence of normal levels of mitochondrial transcripts, in this study, demonstrates the effectiveness of the antioxidant defense systems.