Abstract
Abstract: :
Purpose: Recently, this laboratory has reported on the antioxidative defenses (AODs) of an immortal murine cell line (αTN4-1) conditioned to survive H2O2 (H), tertiary butylhydroperoxide (TBHP) (T) and both H2O2 and TBHP (HT). Such analyses were based on the assumption that both classical and atypical AODs would be recognized on the basis of available information. However, unknown AODs may also be of importance. Therefore, we have initiated an examination of global gene expression in an attempt to uncover new AOD genes and examine previous results. Methods: The expression of 12,422 genes and ESTs were analyzed with Affymetrix murine microarrays. The data was examined by a variety of statistical techniques including one way ANOVA, Tukey test for contrasts and two tailed T test assuming unequal variance as well as Affymetrix and Microsoft software programs. H/C, T/C and HT/C log ratios were then compared with each other. Results: Based on the analyses of gene expression utilizing the statistical methodology indicated above, the following results were obtained. In the T/C versus HT/C comparison, a remarkably close fit was found and examination of H/C versus T/C, while being rather similar, showed somewhat greater scatter. 149 genes were found with increased expression in all three comparisons, H/C, T/C and HT/C, and 311 with decreased expression in all three comparisons. Either H2O2 or TBHP initiated gene expression in 16 genes and shut off 29 genes. H2O2 did not exclusively initiate or shut off gene expression of any of the 12,422 genes while TBHP exclusively initiated expression of 6 genes but did not turn off expression of any gene. Certain genes were found to be exquisitely responsive to a given peroxide. TBHP caused increased expression of 10 genes in both T and HT lines but these genes were found to be essentially unaffected or have decreased expression in the H cell line. Conversely, 12 genes were found with essentially no change or increased expression in the H line but decreased expression when TBHP was present as illustrated with the T and HT lines. The genes found by this analysis will be discussed. Conclusions: Global gene analysis of conditioned cell lines has revealed a relatively small number of previously undetected genes whose expression is significantly affected by H2O2, TBHP or both peroxides
Keywords: gene/expression • oxidation/oxidative or free radical damage • stress response