Telomeric repeat mutagenicity in human somatic cells is modulated by repeat orientation and G-quadruplex stability.
Telomeric repeat mutagenicity in human somatic cells is modulated by repeat orientation and G-quadruplex stability.
复制标题
DOI：
10.1016/j.dnarep.2010.07.014
复制
发表时间：
2010-11-10
期刊：
影响因子：
3.8
通讯作者：
Opresko PL
中科院分区：
文献类型：
--
作者：
Damerla RR;Knickelbein KE;Kepchia D;Jackson A;Armitage BA;Eckert KA;Opresko PL
由富含鸟嘌呤的串联重复序列组成的端粒可以形成称为 G-四链体的二级 DNA 结构，代表 DNA 修复酶的潜在靶标。虽然 G-四链体在体外干扰 DNA 合成，但 G-四链体形成对人类细胞中端粒重复复制的影响尚不清楚。我们使用穿梭载体诱变试验研究了端粒重复序列的致突变性作为 G-四链体折叠机会和热稳定性的函数。由于滞后链复制过程中的单链 DNA 增加了 G 四链体折叠的机会，因此我们测试了滞后链与前导链上具有富含 G 序列的载体。与我们的预测相反，在正常人细胞中复制后，含有富含 G 的滞后链的人 [TTAGGG]10 重复序列的载体的诱变性明显低于含有富含 G 的前导链的载体。我们通过 UV 熔化实验表明，与人类 [TTAGGG]4 相比，来自纤毛虫 [TTGGGG]4 和 [TTTTGGGG]4 的 G-四链体具有更热稳定性。与此一致的是，与人类 [TTAGGG]10 载体相比，具有纤毛虫 [TTGGGG]10 重复序列的载体的复制产生了 3 倍高的突变率。此外，与人类重复序列相比，我们在纤毛虫重复序列中观察到明显更多的诱变事件。我们的数据表明，人端粒重复中增加的 G-四链体机会（重复方向）降低了致突变性，而端粒 G-四链体的热稳定性增加与致突变性增加相关。
Telomeres consisting of tandem guanine-rich repeats can form secondary DNA structures called G-quadruplexes that represent potential targets for DNA repair enzymes. While G-quadruplexes interfere with DNA synthesis in vitro, the impact of G-quadruplex formation on telomeric repeat replication in human cells is not clear. We investigated the mutagenicity of telomeric repeats as a function of G-quadruplex folding opportunity and thermal stability using a shuttle vector mutagenesis assay. Since single stranded DNA during lagging strand replication increases the opportunity for G-quadruplex folding, we tested vectors with G-rich sequences on the lagging versus the leading strand. Contrary to our prediction, vectors containing human [TTAGGG]10 repeats with a G-rich lagging strand were significantly less mutagenic than vectors with a G-rich leading strand, after replication in normal human cells. We show by UV melting experiments that G-quadruplexes from ciliates [TTGGGG]4 and [TTTTGGGG]4 are thermally more stable compared to human [TTAGGG]4. Consistent with this, replication of vectors with ciliate [TTGGGG]10 repeats yielded a 3-fold higher mutant rate compared to the human [TTAGGG]10 vectors. Furthermore, we observed significantly more mutagenic events in the ciliate repeats compared to the human repeats. Our data demonstrate that increased G-quadruplex opportunity (repeat orientation) in human telomeric repeats decreased mutagenicity, while increased thermal stability of telomeric G-qaudruplexes was associated with increased mutagenicity.
登录
查看更多内容
影响因子：
64.8
作者：
Cheng, MY;Bullock, CM;Zhou, QY
通讯作者：
Zhou, QY
影响因子：
4.8
作者：
Aiyar A;Aras S;Washington A;Singh G;Luftig RB
通讯作者：
Luftig RB
影响因子：
56.9
作者：
Courcelle, J;Donaldson, JR;Courcelle, CT
通讯作者：
Courcelle, CT
影响因子：
10.5
作者：
Duquette, ML;Handa, P;Maizels, N
通讯作者：
Maizels, N
影响因子：
30.8
作者：
Broccoli, D;Smogorzewska, A;deLange, T
通讯作者：
deLange, T