PT - JOURNAL ARTICLE AU - Liao, Chunyan AU - Hu, Bin AU - Arno, Matthew J. AU - Panaretou, Barry TI - Genomic Screening in Vivo Reveals the Role Played by Vacuolar H<sup>+</sup> ATPase and Cytosolic Acidification in Sensitivity to DNA-Damaging Agents Such as Cisplatin AID - 10.1124/mol.106.030494 DP - 2007 Feb 01 TA - Molecular Pharmacology PG - 416--425 VI - 71 IP - 2 4099 - http://molpharm.aspetjournals.org/content/71/2/416.short 4100 - http://molpharm.aspetjournals.org/content/71/2/416.full SO - Mol Pharmacol2007 Feb 01; 71 AB - Screening the Saccharomyces cerevisiae homozygous diploid deletion library against a sublethal concentration of cisplatin revealed 76 strains sensitive to the drug. As expected, the largest category of deletions, representing 40% of the sensitive strains, was composed of strains lacking genes involved in DNA replication and damage repair. Deletions lacking function of the highly conserved vacuolar H+ translocating ATPase (V-ATPase) composed the category representing the second largest number of sensitive strains. The effect on cell death exhibited by V-ATPase mutants was found to be a general response to various DNA damaging agents as opposed to being specific to cisplatin, as evidenced by sensitivity of the mutants to hydroxyurea (a DNA-alkylating agent) and UV irradiation. Loss of V-ATPase does not affect DNA repair, because double mutants defective for V-ATPase function and DNA repair pathways were more sensitive to cisplatin than the single mutants. V-ATPase mutants are more prone to DNA damage than wild-type cells, indicated by enhanced activation of the DNA damage checkpoint. Vacuole function per se is not cisplatin-sensitive, because vacuolar morphology and vacuolar acidification were unaffected by cisplatin in wild-type cells. V-ATPase also controls cytoplasmic pH, so the enhanced sensitivity to DNA damage may be associated with the drop in pHi associated with V-ATPase mutants. The increased loss in cell viability induced by cisplatin at lower pH in V-ATPase mutants supports this hypothesis. The loss in viability seen in wild-type cells under the same conditions was far less dramatic. The American Society for Pharmacology and Experimental Therapeutics