Synthesis-dependent microhomology-mediated end joining accounts for multiple types of repair junctions.
Synthesis-dependent microhomology-mediated end joining accounts for multiple types of repair junctions.
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DOI：
10.1093/nar/gkq379
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发表时间：
2010-09
影响因子：
14.9
通讯作者：
McVey M
中科院分区：
文献类型：
--
作者：
Yu AM;McVey M
KU或DNA连接酶4非依赖的末端连接(ALT-EJ)修复DNA双链断裂(DSB)经常与连接微同源性增加相关。然而，ALT-EJ也产生没有微同源性的连接(明显的钝性连接)，微同源性在ALT-EJ和经典的非同源末端连接(NHEJ)中的确切作用尚不清楚。为了更好地了解ALT-EJ对现有微同源的退火程度，我们研究了果蝇中缺乏附近大于四个核苷酸的微同源的I-SCEI DSB的不准确修复。Lig4缺失对连接微同源性的频率和长度都没有影响，但显著增加了插入频率。许多插页似乎都是模板化的。基于修复连接的序列分析，我们提出了一种合成依赖的微同源介导的末端连接(SD-MMEJ)模型，在该模型中，精确的非进行性DNA聚合酶从头合成产生微同源。修复连接具有明显的钝性连接、连接微同源和短插入(缺失和插入)通常被认为反映了不同的修复机制。然而，每种类型的大多数都具有与我们的SD-MMEJ模型预测一致的结构。这表明，一个单一的潜在机制可能负责所有三种维修产品类型。遗传分析表明，SD-MMEJ不依赖于Ku70、Lig4和RAD51，但在Mus308(POLQ)突变体中受损。
Ku or DNA ligase 4-independent alternative end joining (alt-EJ) repair of DNA double-strand breaks (DSBs) frequently correlates with increased junctional microhomology. However, alt-EJ also produces junctions without microhomology (apparent blunt joins), and the exact role of microhomology in both alt-EJ and classical non-homologous end joining (NHEJ) remains unclear. To better understand the degree to which alt-EJ depends on annealing at pre-existing microhomologies, we examined inaccurate repair of an I-SceI DSB lacking nearby microhomologies of greater than four nucleotides in Drosophila. Lig4 deficiency affected neither frequency nor length of junctional microhomology, but significantly increased insertion frequency. Many insertions appeared to be templated. Based on sequence analysis of repair junctions, we propose a model of synthesis-dependent microhomology-mediated end joining (SD-MMEJ), in which de novo synthesis by an accurate non-processive DNA polymerase creates microhomology. Repair junctions with apparent blunt joins, junctional microhomologies and short indels (deletion with insertion) are often considered to reflect different repair mechanisms. However, a majority of each type had structures consistent with the predictions of our SD-MMEJ model. This suggests that a single underlying mechanism could be responsible for all three repair product types. Genetic analysis indicates that SD-MMEJ is Ku70, Lig4 and Rad51-independent but impaired in mus308 (POLQ) mutants.
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DOI：
10.1073/pnas.0915067107
发表时间：
2010-02-16
影响因子：
11.1
作者：
Boboila, Cristian;Jankovic, Mila;Alt, Frederick W.
通讯作者：
Alt, Frederick W.
影响因子：
4.8
作者：
Liang, F;Jasin, M
通讯作者：
Jasin, M
影响因子：
14.9
作者：
Gorbunova, V;Levy, AA
通讯作者：
Levy, AA
影响因子：
3.3
作者：
Koundakjian, EJ;Cowan, DM;Becker, AH
通讯作者：
Becker, AH
影响因子：
5.6
作者：
Feschenko, VV;Lovett, ST
通讯作者：
Lovett, ST