Mammalian polymerase θ promotes alternative NHEJ and suppresses recombination.
Mammalian polymerase θ promotes alternative NHEJ and suppresses recombination.
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DOI：
10.1038/nature14157
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发表时间：
2015-02-12
期刊：
影响因子：
64.8
通讯作者：
Sfeir A
中科院分区：
文献类型：
--
作者：
Mateos-Gomez PA;Gong F;Nair N;Miller KM;Lazzerini-Denchi E;Sfeir A
替代性非同源末端连接（alt-NHEJ）机制促进了许多基因组重排，其中一些可以导致细胞转化。这种易错修复途径在端粒去保护后被触发，以促进有害染色体端对端融合的形成。使用下一代测序技术，我们发现通过alt-NHEJ的修复在功能失调的端粒的融合断点处产生非TTAGGG核苷酸插入。研究负责随机插入的酶活性使我们能够鉴定聚合酶θ（Polθ;由PolQ编码）为哺乳动物细胞中的关键alt-NHEJ因子。PolQ抑制在功能失调的端粒处抑制alt-NHEJ，并且在非端粒基因座处阻碍染色体易位。此外，我们发现PolQ缺失导致同源定向修复（HDR）的速率增加，这通过功能失调的端粒的重组和Rad 51在双链断裂处的积累而明显。最后，我们表明，PolQ的耗竭对BRCA基因缺失的细胞存活具有协同作用，这表明抑制这种致突变聚合酶代表了一种有效的治疗途径，用于携带HDR基因突变的肿瘤。
The alternative nonhomologous end-joining (alt-NHEJ) machinery facilitates a number of genomic rearrangements, some of which can lead to cellular transformation. This error-prone repair pathway is triggered upon telomere de-protection to promote the formation of deleterious chromosome end-to-end fusions. Using next-generation sequencing technology, we found that repair by alt-NHEJ yields non-TTAGGG nucleotide insertions at fusion breakpoints of dysfunctional telomeres. Investigating the enzymatic activity responsible for the random insertions enabled us to identify Polymerase theta (Polθ; encoded by PolQ) as a critical alt-NHEJ factor in mammalian cells. PolQ inhibition suppresses alt-NHEJ at dysfunctional telomeres, and hinders chromosomal translocations at non-telomeric loci. In addition, we found that PolQ loss results in increased rates of homology directed repair (HDR), evident by recombination of dysfunctional telomeres and accumulation of Rad51 at double stranded breaks. Lastly, we show that depletion of PolQ has a synergistic impact on cell survival in the absence of BRCA genes, suggesting that the inhibition of this mutagenic polymerase represents a valid therapeutic avenue for tumors carrying mutations in HDR genes.