Defects in XRCC4 and KU80 differentially affect the joining of distal nonhomologous ends
Defects in XRCC4 and KU80 differentially affect the joining of distal nonhomologous ends
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DOI：
10.1073/pnas.0708541104
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发表时间：
2007-12-26
影响因子：
11.1
通讯作者：
Lopez, Bernard S.
中科院分区：
文献类型：
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作者：
Guirouilh-Barbat, Jose;Rass, Emilie;Lopez, Bernard S.
XRCC4缺失的小鼠比KU80缺失的小鼠有更严重的表型。在这里，我们讨论这种表型差异是否与非同源末端连接(NHEJ)有关。我们使用染色体内底物来监测活细胞中I-SCEL靶向的两个末端双链断裂(DSB)的NHEJ。在xrcc4缺陷的XR-1细胞中，存在残留但显著的末端连接过程，主要使用DSB远端的微同源。然而，与KU缺陷的Xrs6细胞相比，Xrcc4缺陷的XR-1细胞的NHEJ效率显著降低，其末端连接水平与补充细胞相似。然而，修复连接的序列分析表明，在xrcc4缺陷和KU缺陷的细胞中，末端连接的准确性都受到强烈的影响。更具体地说，这些数据表明KU80/XRCC4途径是保守的，本质上不容易出错，但可以容纳非完全互补的末端，但代价是有限的突变。
XRCC4-null mice have a more severe phenotype than KU80-null mice. Here, we address whether this difference in phenotype is connected to nonhomologous end-joining (NHEJ). We used intrachromosomal substrates to monitor NHEJ of two distal double-strand breaks (DSBs) targeted by I-Scel, in living cells. In xrcc4-defective XR-1 cells, a residual but significant end-joining process exists, which primarily uses microhomologies distal from the DSB. However, NHEJ efficiency was strongly reduced in xrcc4-defective XR-1 cells versus complemented cells, contrasting with KU-deficient xrs6 cells, which showed levels of end-joining similar to those of complemented cells. Nevertheless, sequence analysis of the repair junctions indicated that the accuracy of end-joining was strongly affected in both xrcc4-deficient and KU-deficient cells. More specifically, these data showed that the KU80/XRCC4 pathway is conservative and not intrinsically error-prone but can accommodate non-fully complementary ends at the cost of limited mutagenesis.