Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, China.
University of Science and Technology of China, Hefei, China.
Commun Biol. 2024 Aug 3;7(1):936. doi: 10.1038/s42003-024-06640-5.
The repair of DNA double-strand breaks (DSBs) through alternative non-homologous end-joining (alt-NHEJ) pathway significantly contributes to genetic instability. However, the mechanism governing alt-NHEJ pathway choice, particularly its association with DSB complexity, remains elusive due to the absence of a suitable reporter system. In this study, we established a unique Escherichia coli reporter system for detecting complex DSB-initiated alternative end-joining (A-EJ), an alt-NHEJ-like pathway. By utilizing various types of ionizing radiation to generate DSBs with varying degrees of complexity, we discovered that high complexity of DSBs might be a determinant for A-EJ choice. To facilitate efficient repair of high-complexity DSBs, A-EJ employs distinct molecular patterns such as longer micro-homologous junctions and non-templated nucleotide addition. Furthermore, the A-EJ choice is modulated by the degree of homology near DSB loci, competing with homologous recombination machinery. These findings further enhance the understanding of A-EJ/alt-NHEJ pathway choice.
通过非同源末端连接（NHEJ）途径修复 DNA 双链断裂（DSBs）会显著导致遗传不稳定性。然而，由于缺乏合适的报告系统，控制非同源末端连接途径选择的机制，特别是其与 DSB 复杂性的关联，仍然难以捉摸。在这项研究中，我们建立了一种独特的大肠杆菌报告系统，用于检测复杂的 DSB 起始的替代末端连接（A-EJ），这是一种类似非同源末端连接（NHEJ）的途径。通过利用各种类型的电离辐射产生具有不同复杂程度的 DSB，我们发现 DSB 复杂性高可能是 A-EJ 选择的决定因素。为了促进高效修复高复杂性的 DSB，A-EJ 采用了不同的分子模式，如更长的微同源连接和无模板核苷酸添加。此外，A-EJ 的选择受到 DSB 位置附近同源性程度的调节，与同源重组机制竞争。这些发现进一步增强了对 A-EJ/alt-NHEJ 途径选择的理解。
