Paparatto Domenica, Fletcher Dane, Piwowar Karen, Baldino Kimberly, Morel Charlotte, Dunaway Stephen
Department of Biology, Drew University, Madison, New Jersey, USA.
PLoS One. 2009 Jul 9;4(7):e6181. doi: 10.1371/journal.pone.0006181.
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.
METHODOLOGY/PRINCIPAL FINDINGS: 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/SIGNIFICANCE: 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.
DNA损伤检查点确保在整个真核细胞周期中基因组DNA的完整性得到忠实维持。在存在受损DNA的情况下，检查点被触发以延迟细胞周期进程，以便进行DNA修复。在裂殖酵母中，激酶Chk1和Cds1是这些DNA损伤检查点途径的主要组成部分。Chk1和Cds1在存在几种DNA损伤剂时对细胞活力都很重要。在本研究中，我们假设Chk1和Cds1在裂殖酵母细胞暴露于DNA损伤剂顺铂后的存活能力中起着至关重要的作用。顺铂是一种强效化疗药物，它与DNA相互作用并导致链间和链内DNA交联。
方法/主要发现：在此，我们证明在裂殖酵母中用顺铂处理会引起Chk1依赖性DNA损伤信号。chk1(-)细胞对顺铂敏感，并且Chk1在顺铂处理后被磷酸化。我们还表明，在用顺铂挑战的细胞中，Chk1依赖性DNA损伤检查点途径以剂量依赖性方式被激活。此外，Cds1检查点激酶对顺铂挑战细胞的活力也很重要。在cds1(-)细胞中，顺铂处理降低了细胞活力，并且在chk1(-)/cds1(-)背景下这种表型会加剧。
结论/意义：因此，我们得出结论，裂殖酵母中两种主要检查点激酶Chk1和Cds1的协同作用可保护细胞免受顺铂诱导的DNA损伤。这些观察结果具有重要意义，因为它们表明各类链间交联剂可能产生略有不同的损伤，因为其他人的研究未观察到用氮芥等其他交联剂处理的cds1(-)细胞中活力丧失的情况。
