Menadione And Hydrogen Peroxide Trigger Specific Alterations In Rna Polymerases Profiles In Quiescent Saccharomyces Cerevisiae Cells

Yeasts Saccharomyces cerevisiae, like other microbes in nature, respond to the unavailability of nutrients with entrance in quiescent/G(0) state. These cells exist in non-dividing, latent form by maintaining the cellular metabolism at a low level but still able to sense and adapt to environmental stresses. Their quiescent status characteristics are likely close to those of tissues and organs in mammals and humans. This fact makes them an appropriate model system for investigation of the basic mechanisms underlying the toxicity of different chemical compounds. In this study, the toxic effect of H2O2 and menadione on quiescent S. cerevisiae cells was evaluated through the analysis of RNA polymerases transcription profile and ribosomal RNA content. Distinct RNA polymerases subunits were expressed in G(0) yeast cells after short exposure to 0.1 mmol/L menadione and 5 mmol/L hydrogen peroxide. Significant transcription repression of RNA polymerases genes was observed as a response to menadione. Both stress agents induced changes in the 25S and 18S rRNA profile in quiescent and proliferating yeast cells. These results strongly suggest that the toxicological response of eukaryotic cells involves rapid alterations in RNA polymerases gene expression and changes in RNA transcriptome profiles, and depends on the specific mechanism of toxic action.