Rad52 competes with Ku70/Ku86 for binding to S-region DSB ends to modulate antibody class-switch DNA recombination.
Rad52 competes with Ku70/Ku86 for binding to S-region DSB ends to modulate antibody class-switch DNA recombination.
复制标题
DOI：
10.1038/ncomms14244
复制
发表时间：
2017-02-08
影响因子：
16.6
通讯作者：
Casali P
中科院分区：
文献类型：
--
作者：
Zan H;Tat C;Qiu Z;Taylor JR;Guerrero JA;Shen T;Casali P
抗体类别转换 DNA 重组 (CSR) 由 AID 引入的 DSB 在目标重组的转换 (S) 区域启动，并受到 Ku70/Ku86 介导的 NHEJ 的影响。然而，Ku 缺陷的 B 细胞通过替代的 (A)-NHEJ 途径经历（减少的）CSR，该途径在 S-S 连接中引入了微同源性。由于微同源介导的末端连接需要单链 DNA 末端的退火，因此我们讨论了单链退火因子 HR Rad52 和跨损伤 DNA 聚合酶 θ 对 CSR 的贡献。与显示正常 CSR 的 Rad52+/+ 对应细胞相比，Rad52−/− B 细胞显示出 CSR 增加、Sμ 区内重组减少、S-S 连接中无/极少的微同源性、c-Myc/IgH 易位减少以及 Ku70/Ku86 向 S 区 DSB 末端的募集增加。 Rad52 与 Ku70/Ku86 竞争结合 S 区 DSB 末端。它还促进独立于 Ku 的 DSB 修复，有利于 S 区域内重组并介导（特别是在 Ku 缺失的情况下）S-S 间重组，正如在 Ku86 敲低后 Rad52−/− 与 Rad52+/+ B 细胞相比，Rad52+/+ B 细胞的 CSR 显着降低所强调的那样。类别转换 DNA 重组 (CSR) 对于抗体反应的成熟至关重要，并且依赖于 IgH S 区域中 DSB 的 Ku 介导的 NHEJ 进行重组。这项研究表明，Rad52 通过一种独立于 Ku 的替代 NHEJ 来促进 CSR，该 NHEJ 在 S-S 连接中引入了微同源性。
Antibody class-switch DNA recombination (CSR) is initiated by AID-introduced DSBs in the switch (S) regions targeted for recombination, as effected by Ku70/Ku86-mediated NHEJ. Ku-deficient B cells, however, undergo (reduced) CSR through an alternative(A)-NHEJ pathway, which introduces microhomologies in S–S junctions. As microhomology-mediated end-joining requires annealing of single-strand DNA ends, we addressed the contribution of single-strand annealing factors HR Rad52 and translesion DNA polymerase θ to CSR. Compared with their Rad52+/+ counterparts, which display normal CSR, Rad52−/− B cells show increased CSR, fewer intra-Sμ region recombinations, no/minimal microhomologies in S–S junctions, decreased c-Myc/IgH translocations and increased Ku70/Ku86 recruitment to S-region DSB ends. Rad52 competes with Ku70/Ku86 for binding to S-region DSB ends. It also facilitates a Ku-independent DSB repair, which favours intra-S region recombination and mediates, particularly in Ku absence, inter-S–S recombination, as emphasized by the significantly greater CSR reduction in Rad52−/− versus Rad52+/+ B cells on Ku86 knockdown. Class switch DNA recombination (CSR) is critical for maturation of antibody response, and relies on Ku-mediated NHEJ of DSBs in the IgH S regions for recombination. This study shows Rad52 contributes to CSR through a Ku-independent alternative NHEJ that introduces microhomologies in S–S junctions.