Alkylation damage causes MMR-dependent chromosomal instability in vertebrate embryos.
Alkylation damage causes MMR-dependent chromosomal instability in vertebrate embryos.
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DOI：
10.1093/nar/gkn341
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发表时间：
2008-07
影响因子：
14.9
通讯作者：
Cuppen E
中科院分区：
文献类型：
--
作者：
Feitsma H;Akay A;Cuppen E
SN 1型烷化剂，如N-甲基-N-亚硝基脲（MNU）和N-乙基-N-亚硝基脲（ENU），是有效的诱变剂。暴露于烷化剂会产生O 6-烷基鸟嘌呤，这是一种被DNA错配修复（MMR）蛋白识别但不可修复的修饰碱基，导致复制叉停滞和细胞死亡。我们使用体细胞突变检测试验来研究体内烷基化损伤对发育中的斑马鱼胚胎的致死率和突变频率的影响。与MMR系统的损伤感应作用一致，缺乏MMR酶MSH 6的突变胚胎在暴露于ENU和MNU后显示出比野生型胚胎更低的致死率。与此一致，烷基化诱导的体细胞突变频率被发现在野生型胚胎中比在msh 6功能丧失突变体中更高。这些突变被发现是染色体畸变，可能是由停滞的复制叉引起的染色体断裂引起的。由于这些染色体断裂在复制时出现，因此预期它们不会通过非同源末端连接来修复。事实上，Ku 70功能丧失突变体被发现与野生型胚胎一样对ENU敏感。两者合计，我们的研究结果表明，在体内烷基化损伤的结果染色体不稳定性和细胞死亡，由于异常处理的MMR诱导停滞复制叉。
SN1-type alkylating agents, like N-methyl-N-nitrosourea (MNU) and N-ethyl-N-nitrosourea (ENU), are potent mutagens. Exposure to alkylating agents gives rise to O6-alkylguanine, a modified base that is recognized by DNA mismatch repair (MMR) proteins but is not repairable, resulting in replication fork stalling and cell death. We used a somatic mutation detection assay to study the in vivo effects of alkylation damage on lethality and mutation frequency in developing zebrafish embryos. Consistent with the damage-sensing role of the MMR system, mutant embryos lacking the MMR enzyme MSH6 displayed lower lethality than wild-type embryos after exposure to ENU and MNU. In line with this, alkylation-induced somatic mutation frequencies were found to be higher in wild-type embryos than in the msh6 loss-of-function mutants. These mutations were found to be chromosomal aberrations that may be caused by chromosomal breaks that arise from stalled replication forks. As these chromosomal breaks arise at replication, they are not expected to be repaired by non-homologous end joining. Indeed, Ku70 loss-of-function mutants were found to be equally sensitive to ENU as wild-type embryos. Taken together, our results suggest that in vivo alkylation damage results in chromosomal instability and cell death due to aberrantly processed MMR-induced stalled replication forks.
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影响因子：
9.2
作者：
Cejka, P;Mojas, N;Jiricny, J
通讯作者：
Jiricny, J
影响因子：
2.8
作者：
KAINA, B;FRITZ, G;COQUERELLE, T
通讯作者：
COQUERELLE, T
影响因子：
2.5
作者：
Bladen, Catherine L.;Navarre, Sammy;Kozlowski, David J.
通讯作者：
Kozlowski, David J.
影响因子：
10.5
作者：
Mojas, Nina;Lopes, Massimo;Jiricny, Josef
通讯作者：
Jiricny, Josef
DOI：
10.1016/j.mrfmmm.2006.11.003
发表时间：
2007-03-01
影响因子：
2.3
作者：
Russell, Liane B.;Hunsicker, Patricia R.;Russell, William L.
通讯作者：
Russell, William L.