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Abstract：
Break-induced replication (BIR) is essential for the repair of DNA double-strand breaks (DSBs) with single ends. DSBs-induced microhomology-mediated BIR (mmBIR) and template-switching can increase the risk of complex genome rearrangement. In addition, DSBs can also induce the multi-invasion-mediated DSB amplification. The mmBIR-induced genomic rearrangement has been identified in cancer cells and patients with rare diseases. However, when and how mmBIR is initiated have not been fully and deeply studied. Furthermore, it is not well understood about the conditions for initiation of multi-invasion-mediated DSB amplification. In the G2 phase oocyte of mouse, we identified a type of short-scale BIR (ssBIR) using the DNA replication indicator 5-ethynyl-2\'-deoxyuridine (EdU). These ssBIRs could only be induced in the fully grown oocytes but not the growing oocytes. If the DSB oocytes were treated with Rad51 or Chek1/2 inhibitors, both EdU signals and DSB marker γH2A.X foci would decrease. In addition, the DNA polymerase inhibitor Aphidicolin could inhibit the ssBIR and another inhibitor ddATP could reduce the number of γH2A.X foci in the DSB oocytes. In conclusion, our results showed that DNA DSBs in the fully grown oocytes can initiate ssBIR and be amplified by Rad51 or DNA replication.
摘要：
断裂诱导的复制（BIR）对于修复具有单末端的DNA双链断裂（DSB）至关重要。DSB诱导的微同源介导的BIR（mmBIR）和模板转换可以增加复杂基因组重排的风险。此外,DSB还可以诱导多侵袭介导的DSB扩增。已经在癌细胞和罕见疾病患者中鉴定了mmBIR诱导的基因组重排。然而,何时以及如何启动MMBIR尚未得到充分和深入的研究。此外，关于多次侵袭介导的DSB扩增的起始条件尚不清楚。在小鼠的G2期卵母细胞中，我们使用DNA复制指标5-乙炔基-2'-脱氧尿苷（EdU）鉴定了一种短期BIR（ssBIR）。这些ssBIR只能在完全生长的卵母细胞中诱导，而不能在生长的卵母细胞中诱导。如果用Rad51或Chek1/2抑制剂处理DSB卵母细胞，EdU信号和DSB标记γH2A。X焦点会减少。此外,DNA聚合酶抑制剂Aphidicolin可以抑制ssBIR，另一种抑制剂ddATP可以减少γH2A的数量。DSB卵母细胞中的X灶。总之,我们的结果表明，完全生长的卵母细胞中的DNADSB可以启动ssBIR并通过Rad51或DNA复制进行扩增。
