Department of Developmental Biology, Erasmus MC - University Medical Center, Rotterdam, The Netherlands.
Erasmus Optical Imaging Centre, Department of Pathology, Erasmus MC - University Medical Center, Rotterdam, The Netherlands.
DNA Repair (Amst). 2018 Mar;63:25-38. doi: 10.1016/j.dnarep.2018.01.007. Epub 2018 Jan 31.
Repair of SPO11-dependent DNA double-strand breaks (DSBs) via homologous recombination (HR) is essential for stable homologous chromosome pairing and synapsis during meiotic prophase. Here, we induced radiation-induced DSBs to study meiotic recombination and homologous chromosome pairing in mouse meiocytes in the absence of SPO11 activity (Spo11 model), and in the absence of both SPO11 and HORMAD1 (Spo11/Hormad1 dko). Within 30 min after 5 Gy irradiation of Spo11 mice, 140-160 DSB repair foci were detected, which specifically localized to the synaptonemal complex axes. Repair of radiation-induced DSBs was incomplete in Spo11 compared to Spo11 meiocytes. Still, repair of exogenous DSBs promoted partial recovery of chromosome pairing and synapsis in Spo11 meiocytes. This indicates that at least part of the exogenous DSBs can be processed in an interhomolog recombination repair pathway. Interestingly, in a seperate experiment, using 3 Gy of irradiation, we observed that Spo11/Hormad1 dko spermatocytes contained fewer remaining DSB repair foci at 48 h after irradiation compared to irradiated Spo11 knockout spermatocytes. Together, these results show that recruitment of exogenous DSBs to the synaptonemal complex, in conjunction with repair of exogenous DSBs via the homologous chromosome, contributes to homology recognition. In addition, the data suggest a role for HORMAD1 in DNA repair pathway choice in mouse meiocytes.
SPO11 依赖性 DNA 双链断裂 (DSBs) 的修复通过同源重组 (HR) 对于减数分裂前期稳定的同源染色体配对和联会至关重要。在这里，我们通过诱导辐射诱导的 DSBs 来研究减数分裂重组和同源染色体配对，在缺乏 SPO11 活性的情况下（Spo11 模型），以及在缺乏 SPO11 和 HORMAD1 的情况下（Spo11/Hormad1 dko）。在 Spo11 小鼠接受 5Gy 辐射后的 30 分钟内，检测到 140-160 个 DSB 修复焦点，这些焦点特异性定位于联会复合体轴上。与 Spo11 减数分裂细胞相比，Spo11 中辐射诱导的 DSBs 修复不完全。尽管如此，外源 DSBs 的修复促进了 Spo11 减数分裂细胞中染色体配对和联会的部分恢复。这表明至少部分外源 DSBs 可以通过同源重组修复途径进行处理。有趣的是，在一个独立的实验中，使用 3Gy 的辐射，我们观察到 Spo11/Hormad1 dko 精母细胞在辐射后 48 小时内的剩余 DSB 修复焦点比受照射的 Spo11 敲除精母细胞少。总之，这些结果表明，外源 DSBs 向联会复合体的募集，与通过同源染色体修复外源 DSBs 相结合，有助于同源性识别。此外，数据表明 HORMAD1 在小鼠减数分裂细胞中 DNA 修复途径选择中发挥作用。
