Abstract
Abstract: :
Purpose: Cells adapt to stress through changes in gene expression, protein expression and protein modification. The purpose of this study was to elucidate mechanisms of adaptation to peroxide stress. Protein expression was analyzed in the murine immortal lens epithelial cell line, alpha TN4–1, and the cells were conditioned to grow on high concentrations of hydrogen peroxide (HP) or t–butyl hydroperoxide (TBHP). Methods: Protein expression patterns were compared among control cells and cells conditioned to grow in the presence of 125 uM hydrogen peroxide or 130 uM TBHP (Spector et al, (2000) IOVS 41, 832). Proteins were separated by 2D electrophoresis. The resulting protein patterns were quantified using Progenesis image analysis software. Differentially expressed proteins were identified using mass spectrometry. Results: Cells conditioned to grow in TBHP survive growth in HP; the reverse is not true. The expression of at least 30 proteins was increased more than 4 fold in cells conditioned to grow in either peroxide relative to control cells. The expression of about 20 proteins varied more than 4 fold between HP and TBHP conditioned cells. As expected, peroxide conditioned cells expressed a high concentration of catalase. Concentrations reached were comparable with both peroxides and when peroxide stress was removed the concentrations of the protein remained. A major difference between HP and TBHP conditioned cells was a large increase in the concentration of a 47 kD protein in TBHP conditioned cells. Glutathione S–transferase, classes pi and alpha, GRP78, peroxiredoxin, aldolase, ferritin light chain and HSP60 are among the proteins with increased expression in peroxide conditioned cells. Conclusions: Adaptation of cells to grow in the presence of high concentrations of peroxides involves increased expression of stress, detoxification, antioxidant and metabolic proteins. p47 may be the major protein in adaptation of cells to TBHP relative to HP and may have a role in protecting cells against lipid peroxides.
Keywords: proteomics • stress response • protein modifications–post translational