title: Signaling of chloroquine-induced stress in the yeast Saccharomyces cerevisiae requires the Hog1 and Slt2 mitogen-activated protein kinase pathways.
abstract: Chloroquine (CQ) has been under clinical use for several decades, and yet little is known about CQ sensing and signaling mechanisms or about their impact on various biological pathways. We employed the budding yeast Saccharomyces cerevisiae as a model organism to study the pathways targeted by CQ. Our screening with yeast mutants revealed that it targets histone proteins and histone deacetylases (HDACs). Here, we also describe the novel role of mitogen-activated protein kinases Hog1 and Slt2, which aid in survival in the presence of CQ. Cells deficient in Hog1 or Slt2 are found to be CQ hypersensitive, and both proteins were phosphorylated in response to CQ exposure. CQ-activated Hog1p is translocated to the nucleus and facilitates the expression of GPD1 (glycerol-3-phosphate dehydrogenase), which is required for the synthesis of glycerol (one of the major osmolytes). Moreover, cells treated with CQ exhibited an increase in intracellular reactive oxygen species (ROS) levels and the effects were rescued by addition of reduced glutathione to the medium. The deletion of SOD1, the superoxide dismutase in yeast, resulted in hypersensitivity to CQ. We have also observed P38 as well as P42/44 phosphorylation in HEK293T human cells upon exposure to CQ, indicating that the kinds of responses generated in yeast and human cells are similar. In summary, our findings define the multiple biological pathways targeted by CQ that might be useful for understanding the toxicity modulated by this pharmacologically important molecule.
authors.affiliation: Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India.
authors.forename: Shivani
authors.initials: S
authors.lastname: Baranwal
authors.affiliation: Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India.
authors.forename: Gajendra Kumar
authors.initials: GK
authors.lastname: Azad
authors.affiliation: Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India.
authors.forename: Vikash
authors.initials: V
authors.lastname: Singh
authors.affiliation: Laboratory of Chromatin Biology, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, India rst@iiserb.ac.in.
authors.forename: Raghuvir S
authors.initials: RS
authors.lastname: Tomar
mesh_terms: D021581:Active Transport, Cell Nucleus; D000962:Antimalarials / Q000494:pharmacology*; D002460:Cell Line; D002738:Chloroquine / Q000494:pharmacology*; D025141:Drug Resistance, Fungal / Q000235:genetics; D005978:Glutathione / Q000737:chemistry; D005993:Glycerolphosphate Dehydrogenase / Q000096:biosynthesis; D057809:HEK293 Cells; D006801:Humans; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013312:Stress, Physiological / Q000187:drug effects; D013482:Superoxide Dismutase / Q000235:genetics; D000072105:Superoxide Dismutase-1; D014157:Transcription Factors / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D000962:Antimalarials; D017382:Reactive Oxygen Species; C000606290:SOD1 protein, human; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C478359:WDR77 protein, human; D002738:Chloroquine; D005993:Glycerolphosphate Dehydrogenase; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; C088589:HOG1 protein, S cerevisiae; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D020928:Mitogen-Activated Protein Kinases; C072724:SLT2 protein, S cerevisiae; D048051:p38 Mitogen-Activated Protein Kinases; D005978:Glutathione