Mitochondrial DNA protects against salt stress-induced cytochrome c-mediated apoptosis in yeast.

Here we report that budding yeast mitochondrial DNA protects against salt stress-induced apoptosis. Yeast cells lacking mitochondrial DNA (ρ(0)) are hypersensitive to salt stress-induced apoptosis, which is mediated by mitochondrial cytochrome c release. In addition, cytochrome c expression is downregulated upon salt stress, suggesting a transcriptionally regulated, homeostatic protection mechanism. The repression of cytochrome c transcription is mediated by transcription factor Mig1. Consistently, deletion of MIG1 induces cytochrome C transcription and yields ρ(0) cells that are more sensitive to salt stress. In summary, deletion of mitochondrial function leads to salt stress-induced transcriptional deregulation of cytochrome C, causing apoptosis in yeast.