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The control of the yeast H2O2 response by the Msn2/4 transcription factors
Rukhsana Hasan1, Christophe Leroy, Anne-Dominique Isnard
1Laboratoire Information Génétique et Développement, Institut de Génétique et de Microbiologie, UMR C8621, Université Paris-Sud, Orsay, France.
Abstract:
We have analysed the contribution of the Msn2/4 transcription factors and the Ras-cAMP-protein kinase A (PKA) pathway to the control of the yeast H2O2 response. Strains deleted for MSN2 and MSN4 are hypersensitive to H2O2, although they can still adapt to this oxidant. They are also unable to induce 27 proteins of the H2O2 stimulon as shown by quantitative two-dimensional gel analysis. This peculiar H2O2 tolerance defect, the nature of the proteins of the Msn2/4 regulon, and the partial overlap of this regulon with the Yap1 H2O2-response regulon, suggest an independent and distinctive role of these two H2O2 stress response pathways. A strain lacking PDE2, and therefore carrying high intracellular cAMP levels, is also hypersensitive to H2O2. In the presence of exogenous cAMP, this strain does not induce the entire H2O2 Msn2/4 regulon and some other proteins. This, and the normal H2O2 induction of a gene reporter under control of the Yap1 regulator when intracellular cAMP level are high, demonstrate that the Ras-cAMP pathway negatively affects the H2O2 stress response through Msn2/4. However, the high H2O2 sensitivity of a strain lacking the PKA-negative regulatory subunit Bcy1, is not only the consequence of the inhibition of Msn2/4 but also of Yap1 through a yet undefined mechanism.
Insights
The Msn2/4 transcription factors are crucial for yeast
Area of Science:
- * Molecular biology
- * Yeast genetics
- * Stress response pathways
Background:
- * The yeast hydrogen peroxide (H2O2) response involves complex regulatory networks.
- * Transcription factors Msn2/4 and the Ras-cAMP-protein kinase A (PKA) pathway are implicated in cellular defense.
- * Understanding these pathways is key to deciphering oxidative stress tolerance in yeast.
Purpose of the Study:
- * To elucidate the distinct roles of Msn2/4 transcription factors and the Ras-cAMP-PKA pathway in the yeast H2O2 response.
- * To investigate the interplay between these two major oxidative stress response pathways.
- * To identify specific proteins regulated by Msn2/4 under H2O2 stress.
Main Methods:
- * Gene deletion analysis of MSN2 and MSN4.
- * Quantitative two-dimensional gel electrophoresis to analyze protein expression.
- * Assessment of H2O2 sensitivity and adaptation in various yeast strains.
- * Investigation of gene reporter induction under different cAMP conditions.
Main Results:
- * Strains lacking Msn2/4 exhibit hypersensitivity to H2O2 and fail to induce 27 H2O2-responsive proteins.
- * The Ras-cAMP pathway negatively regulates the H2O2 stress response via Msn2/4.
- * High intracellular cAMP levels inhibit Msn2/4-dependent gene induction but not Yap1-dependent induction.
- * Deletion of the PKA regulatory subunit Bcy1 leads to hypersensitivity, affecting both Msn2/4 and Yap1 pathways.
Conclusions:
- * Msn2/4 and the Ras-cAMP-PKA pathway represent distinct yet interconnected arms of the yeast H2O2 stress response.
- * The Ras-cAMP pathway acts as a negative regulator of the Msn2/4-mediated oxidative stress defense.
- * The PKA pathway influences both Msn2/4 and Yap1, suggesting a broader role in oxidative stress signaling.