Stress-Activated Degradation of Sphingolipids Regulates Mitochondrial Function and Cell Death in Yeast

Figure 1

Stress-induced expression of genes encoding outer mitochondrial membrane proteins. (a) Reverse transcriptase determination of mRNA induction of four outer mitochondrial membrane protein encoding genes upon salt shock (0.4 M NaCl) and oxidative stress (50 μM menadione) for the indicated times. The GRE2 gene was included as a positive marker for salt and oxidative stress. Data are presented as mean ± SD. Three biological replicates were analyzed. The mRNA level was normalized in all cases for the ACT1 control, and the uninduced level was arbitrarily set to 1. (b) Representation of consensus binding sites for stress-activated transcription factors in the promoter regions of OM14, RDL1, MCR1, and HFD1. (c) Reverse transcriptase determination of mRNA induction of the same genes in the indicated strain backgrounds upon salt shock (0.4 M NaCl) as described in (a). Significantly different mRNA levels as compared to wt are marked. ; (Student’s t-test). (d) Reactive oxygen species (ROS) production in mutants affected in specific mitochondrial outer membrane proteins. 2′,7′-dichlorodihydrofluorescein diacetate assay in the indicated yeast strains before or after salt (1 M NaCl, 2 h) or oxidative shock (50 μM menadione, 2 h). Data are presented as mean ± SD. Three biological replicates were analyzed. Significantly different ROS levels as compared to wt are marked. ; (Student’s t-test).

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