Effects of camptothecin or TOP1 overexpression on genetic stability in Saccharomyces cerevisiae.
Effects of camptothecin or TOP1 overexpression on genetic stability in Saccharomyces cerevisiae.
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DOI：
10.1016/j.dnarep.2017.09.004
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发表时间：
2017-11
期刊：
影响因子：
3.8
通讯作者：
Jinks-Robertson S
中科院分区：
文献类型：
--
作者：
Sloan R;Huang SN;Pommier Y;Jinks-Robertson S
拓扑异构酶I(Top1)通过切割和重新密封DNA的一条链来消除DNA扭转应力，在高等真核生物中是必不可少的。这种酶经常在肿瘤中过度生产，是化疗药物喜树碱(CPT)及其临床衍生物的唯一靶点。CPT稳定共价Top1-DNA切割中间体，当被复制叉子遇到时，这会导致有毒的双链断裂(DSB)。在目前的研究中，我们研究了与CPT处理或Top1在酿酒酵母中过表达有关的遗传不稳定性。监测到两种类型的不稳定性：单倍体菌株中Top1依赖的缺失，不需要加工成DSB；二倍体菌株中重复核糖体DNA(RDNA)基因座的不稳定性，反映DSB的形成。当野生型菌株被CPT处理或TOP1过表达时，检测到三个2-碱基缺失热点，每个热点上的突变都增加，突变频率与TOP1过表达水平相关。在这两种情况下，新位置的缺失都得到了丰富。通过测量杂合性损失来检测rDNA的稳定性，正如先前在CPT处理野生型菌株Top1过表达不稳定的rDNA时所观察到的那样。我们的结论是，Top1过多和过少对真核基因组都是有害的，CPT的不稳定作用超出了与DSB形成相关的影响。
Topoisomerase I (Top1) removes DNA torsional stress by nicking and resealing one strand of DNA, and is essential in higher eukaryotes. The enzyme is frequently overproduced in tumors and is the sole target of the chemotherapeutic drug camptothecin (CPT) and its clinical derivatives. CPT stabilizes the covalent Top1-DNA cleavage intermediate, which leads to toxic double-strand breaks (DSBs) when encountered by a replication fork. In the current study, we examined genetic instability associated with CPT treatment or with Top1 overexpression in the yeast Saccharomyces cerevisiae. Two types of instability were monitored: Top1-dependent deletions in haploid strains, which do not require processing into a DSB, and instability at the repetitive ribosomal DNA (rDNA) locus in diploid strains, which reflects DSB formation. Three 2-bp deletion hotspots were examined and mutations at each were elevated either when a wild-type strain was treated with CPT or when TOP1 was overexpressed, with the mutation frequency correlating with the level of TOP1 overexpression. Under both conditions, deletions at novel positions were enriched. rDNA stability was examined by measuring loss-of-heterozygosity and as was observed previously upon CPT treatment of a wild-type strain, Top1 overexpression destabilized rDNA. We conclude that too much, as well as too little of Top1 is detrimental to eukaryotic genomes, and that CPT has destabilizing effects that extend beyond those associated with DSB formation.
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影响因子：
112.7
作者：
Pommier, Yves;Sung, Yilun;Huang, Shar-yin N.;Nitiss, John L.
通讯作者：
Nitiss, John L.
影响因子：
3.8
作者：
Myung, K;Kolodner, RD
通讯作者：
Kolodner, RD
DOI：
10.1073/pnas.85.20.7501
发表时间：
1988-10-01
影响因子：
11.1
作者：
NITISS, J;WANG, JC
通讯作者：
WANG, JC
影响因子：
7
作者：
Reid, Robert J. D.;Gonzalez-Barrera, Sergio;Rothstein, Rodney
通讯作者：
Rothstein, Rodney
DOI：
10.1073/pnas.74.11.5091
发表时间：
1977-01-01
影响因子：
11.1
作者：
PETES, TD;BOTSTEIN, D
通讯作者：
BOTSTEIN, D