Hepatic transcriptome and proteome responses against diethyl maleate-induced glutathione depletion in the rat

Hepatic transcriptome and proteome responses against glutathione depletion were investigated by Affymetrix GeneChip Microarray and 2-dimensional gel electrophoresis (2D-DIGE), followed by MALDI-TOF–MS analysis and utilizing a glutathione-depleted rat model treated with diethyl maleate (DEM). Hepatic glutathione content decreased to 1.29 μmol/g liver (25.5% compared to control) after DEM treatment, and there were no apparent hepatotoxic signs estimated by blood chemistry examinations. A total of 247 and 213 annotated gene probe sets exhibited greater than twofold up- and down-regulation compared with controls, respectively. The up-regulated gene list contained a number of glutathione depletion–responsive genes reported previously, such as Trib3, Srxn1, Myc, Asns, Igfbp1, Txnrd1, or Hmox1, suggesting that these genes are robust mRNA biomarkers for evaluating hepatic glutathione depletion. In the 2D-DIGE analysis, proteins for a total of 361 spots were identified by MALDI-TOF–MS analysis. Of the identified proteins, 5 and 14 proteins showed up- and down-regulation, respectively. Some proteins exhibited differential expression in the protein level but not in the mRNA level, including L-FABP, MAWDBP, aldo–keto reductase family 1 member A1, catalase and ATP synthase subunit beta, suggesting that these proteins would be potential protein biomarkers for evaluating glutathione depletion. Moreover, up-regulation of FABP1 protein along with up-regulation of PPARα-regulated gene transcripts (i.e., Acot2 and Acot4) is indicative of PPARα activation, which may contribute to hepatocellular protection against glutathione depletion–induced oxidative stress. The up-regulation of L-FABP1 was detected by proteome data but not by transcriptome data, demonstrating the advantage of utilizing transcriptomics and proteomics combination to investigate glutathione depletion–induced molecular dynamics.