, oppositely, we may speculate that Met6-increase could cause decreased protection against oxidative stress. LYS20 gene expression is also induced after H2O2 treatment. Besides, the proteins Adh1, alcohol dehydrogenase 1, and Aro4, phosphor-2-dehydro-3-deoxyheptonate aldolase, have been previously related to the oxidative stress response. In mammals it has been described that cisplatin treatment causes oxidative stress, which may even become the cause of cell-death. 2.6. Proteins Related to the Increased Resistance of Cisplatin in the sky1 Mutant Although a role of Sky1 in specific DNA repair pathways has been suggested, the mechanisms by which the sky1 mutant becomes more resistant to cisplatin, are unknown. A comparison of data reported in Int. J. Mol. Sci. 2014, 15 12580 2.7. Cisplatin Increases Apoptotic-Like Events in Yeast Cells and Sky1 Modulates this Response As discussed above, among the proteins which change their levels after cisplatin treatment of yeast cells, there are proteins previously related to the oxidative stress response and it is known that redox imbalance and mitochondrial dysfunction targets apoptosis and cell death. Several proteins that are differentially expressed 
in sky1 treated versus untreated cells have been previously related to apoptosis in yeast, like, Bmh2 and Mmi1. Bmh2, shows PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/19820119 strong similarity to the ubiquitous and highly conserved 14-3-3 proteins which likely play a role in signal transduction and protect against stress-induced apoptosis. Mmi1 has been related to apoptosis induced by oxidative stress. Cisplatin, like many other chemotherapeutic drugs, can induce apoptosis in mammals. In yeast a programmed cell-death related to cisplatin treatment has been recently reported. The changes, observed in the proteome analysis after cisplatin treatment and Sky1 depletion, suggest that Sky1 may modulate this cellular response. Int. J. Mol. Sci. 2014, 15 12581 We studied if mitophagy is implicated in the response to cisplatin in yeast and its dependence on Sky1 function. Mitophagy was optically visualized by the method previously described and we observed the presence of mitochondria into vacuole in all the tested strains, which indicates the correct performance of the fluorescent biosensor; one example is shown in Int. J. Mol. Sci. 2014, 15 12582 3. Experimental Section 3.1. UNC0642 chemical information strains and Culture Conditions S. cerevisiae haploid W303-1A and the isogenic sky1 mutant strains were used in this work. The construction of the sky1 strain has been previously described. The strains mmi1, bmh1, bmh2, and their isogenic parental strain BY4741 were obtained from EUROSCARF. Biological replicates of cultures and treatments were run in triplicate. The two yeast strains were pre-cultured overnight in 20 mL of synthetic medium prepared as previously described. The following day the cells were inoculated, at an initial OD600 of 0.05, in 500 mL SD and grown during 14 h at 30 C and with agitation at 250 rpm. Then, the cultures from each strain were split in two of 250 mL and cisplatin was added to the treated cultures at a final concentration of 600 M. The treatment was done at 30 C and with agitation at 250 rpm over four hours in darkness. The concentration of cisplatin and the time course of the treatment were previously established in trial experiments with the selected yeast strains. In the conditions used in these experiments cell survival in the treated cells was over 80% and an increase of 10%15% survival was observed in