Hasan Rukhsana, Leroy Christophe, Isnard Anne-Dominique, Labarre Jean, Boy-Marcotte Emmanuelle, Toledano Michel B
Laboratoire Information Génétique et Développement, Institut de Génétique et de Microbiologie, UMR C8621, Université Paris-Sud, Orsay, France.
Mol Microbiol. 2002 Jul;45(1):233-41. doi: 10.1046/j.1365-2958.2002.03011.x.
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.
我们分析了Msn2/4转录因子和Ras - cAMP - 蛋白激酶A（PKA）信号通路在调控酵母对过氧化氢（H2O2）应答中的作用。缺失MSN2和MSN4的菌株对H2O2高度敏感，尽管它们仍能适应这种氧化剂。二维凝胶定量分析表明，它们也无法诱导H2O2刺激子中的27种蛋白质。这种特殊的H2O2耐受性缺陷、Msn2/4调控子中蛋白质的性质以及该调控子与Yap1 H2O2应答调控子的部分重叠，表明这两条H2O2应激反应通路具有独立且独特的作用。缺乏PDE2因而细胞内cAMP水平较高的菌株，对H2O2也高度敏感。在外源cAMP存在的情况下，该菌株不会诱导整个H2O2 Msn2/4调控子及其他一些蛋白质。此外，当细胞内cAMP水平较高时，Yap1调控下的基因报告基因对H2O2的诱导正常，这表明Ras - cAMP信号通路通过Msn2/4对H2O2应激反应产生负面影响。然而，缺乏PKA负调控亚基Bcy1的菌株对H2O2的高敏感性，不仅是由于Msn2/4受到抑制，还通过一种尚未明确的机制影响了Yap1。
