TY - JOUR T1 - 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 JF - Molecular Pharmacology JO - Mol Pharmacol SP - 416 LP - 425 DO - 10.1124/mol.106.030494 VL - 71 IS - 2 AU - Chunyan Liao AU - Bin Hu AU - Matthew J. Arno AU - Barry Panaretou Y1 - 2007/02/01 UR - http://molpharm.aspetjournals.org/content/71/2/416.abstract N2 - 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 ER -