The Schizosaccharomyces pombe checkpoint kinases Chk1 and Cds1 are important for cell survival in response to cisplatin.
BACKGROUND
DNA damage checkpoints insure that the integrity of genomic DNA is faithfully maintained throughout the eukaryotic cell cycle. In the presence of damaged DNA, checkpoints are triggered to delay cell cycle progression to allow for DNA repair. In fission yeast, the kinases Chk1 and Cds1 are major components of these DNA damage checkpoint pathways. Both Chk1 and Cds1 are important for viability in the presence of several DNA damaging agents. In this study we hypothesized that Chk1 and Cds1 play a vital role in fission yeast cells ability to survive exposure to the DNA damaging agent cisplatin. Cisplatin is a potent chemotherapeutic drug that interacts with DNA and causes both inter- and intra-strand DNA cross-links.


RESULTS
Here, we demonstrated that treatment with cisplatin in fission yeast causes a Chk1-dependent DNA damage signal. chk1(-) cells were sensitive to cisplatin and Chk1 was phosphorylated in response to cisplatin treatment. We also showed that a Chk1-dependent DNA damage checkpoint pathway is activated in a dose-dependent fashion in cells challenged with cisplatin. Furthermore the Cds1 checkpoint kinase was also important for viability in cisplatin challenged cells. In cds1(-) cells, cisplatin treatment reduced cell viability and this phenotype was exacerbated in a chk1(-)/cds1(-) background.


CONCLUSIONS
Thus, we conclude that the concerted effort of both major checkpoint kinases in fission yeast, Chk1 and Cds1, protect cells from cisplatin induced DNA damage. These observations are significant because they suggest that various classes of inter-strand crosslinking agents may generate slightly different lesions as work by others did not observe loss of viability in cds1(-) cells treated with other crosslinking agents like nitrogen mustard.
Paparatto
Domenica
D
Department of Biology, Drew University, Madison, New Jersey, USA.
Fletcher
Dane
D
Piwowar
Karen
K
Baldino
Kimberly
K
Morel
Charlotte
C
Dunaway
Stephen
S
D000970:Antineoplastic Agents / Q000494:pharmacology*; D015153:Blotting, Western; D002470:Cell Survival / Q000187:drug effects*; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D002945:Cisplatin / Q000494:pharmacology*; D004249:DNA Damage; D004591:Electrophoresis, Polyacrylamide Gel; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism / Q000502:physiology*; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism / Q000502:physiology*
D000970:Antineoplastic Agents; D029702:Schizosaccharomyces pombe Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C578636:Cds1 protein, S pombe; D000071877:Checkpoint Kinase 1; C000605873:Chk1 protein, S pombe; D017346:Protein Serine-Threonine Kinases; D002945:Cisplatin