Figure 2.

The constitutive UPR in a trr1 mutant generates ROS and induces the Yap1 response. A, the Yap1 response was assayed in WT, trr1, trx1 trx2, trr1 trx1 trx2, hac1, and trr1 hac1 mutant strains containing a YRE::lacZ fusion construct. β-Gal activity data are shown for exponential-phase calls grown in minimal SD medium and are the means of three independent biological repeat experiments ± S.D. B, hydrogen peroxide levels were measured using a peroxiredoxin-based roGFP2-Tsa2ΔCR H₂O₂ probe in the indicated strains. The degree of sensor OxD is shown with OxD = 1 for the fully oxidized probe and OxD = 0 for the fully reduced probe. Data shown are the means of three independent biological repeat experiments ± S.D. C, ROS generation was measured in the indicated strains using DHR123. D, cytosolic GSH redox potentials were measured in strains using a roGFP2 fluorescent probe that equilibrates with the local GSH pool. Data shown are the means of at least three independent biological repeat experiments ± S.D. E, the Yap1 response is induced in response to ER stress. YRE::lacZ activity was measured in the WT and yap1 mutant strains treated with 1 μg/ml Tm for 2 h. Data shown are the means of three independent biological repeat experiments ± S.D. F, mutants deleted for YAP1 are sensitive to ER stress induced by Tm exposure. Strains were grown to stationary phase, and the A₆₀₀ was adjusted to 1, 0.1, 0.01, or 0.001 before spotting onto SD plates in the presence or absence of 0.4 μg/ml tunicamycin under aerobic or anaerobic growth conditions. Significance is shown compared with the WT strain: *, p < 0.05; **, p < 0.01; ***, p < 0.001.