Ozaki Kie, Kato Reona, Yasuhara Takaaki, Uchihara Yuki, Hirakawa Miyako, Abe Yu, Shibata Hiroki, Kawabata-Iwakawa Reika, Shakayeva Aizhan, Kot Palina, Miyagawa Kiyoshi, Suzuki Keiji, Matsuda Naoki, Shibata Atsushi, Yamauchi Motohiro
Hospital Campus Laboratory, Radioisotope Center, Central Institute of Radioisotope Science and Safety Management, Kyushu University, Fukuoka, 812-8582, Japan.
Laboratory of Molecular Radiology, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan.
Sci Rep. 2024 Aug 8;14(1):18455. doi: 10.1038/s41598-024-68926-2.
Although previous studies have reported that pre-mRNA splicing factors (SFs) are involved in the repair of DNA double-strand breaks (DSBs) via homologous recombination (HR), their exact role in promoting HR remains poorly understood. Here, we showed that SART1, an SF upregulated in several types of cancer, promotes DSB end resection, an essential first step of HR. The resection-promoting function of SART1 requires phosphorylation at threonine 430 and 695 by ATM/ATR. SART1 is recruited to DSB sites in a manner dependent on transcription and its RS domain. SART1 is epistatic with BRCA1, a major HR factor, in the promotion of resection, especially transcription-associated resection in the G2 phase. SART1 and BRCA1 accumulate at DSB sites in an interdependent manner, and epistatically counteract the resection blockade posed by 53BP1 and RIF1. Furthermore, chromosome analysis demonstrated that SART1 and BRCA1 epistatically suppressed genomic alterations caused by DSB misrepair in the G2 phase. Collectively, these results indicate that SART1 and BRCA1 cooperatively facilitate resection of DSBs arising in transcriptionally active genomic regions in the G2 phase, thereby promoting faithful repair by HR, and suppressing genome instability.
尽管先前的研究报道前体mRNA剪接因子（SFs）通过同源重组（HR）参与DNA双链断裂（DSBs）的修复，但其在促进HR中的具体作用仍知之甚少。在此，我们表明SART1（一种在多种癌症中上调的SF）促进DSB末端切除，这是HR必不可少的第一步。SART1促进切除的功能需要ATM/ATR在苏氨酸430和695处进行磷酸化。SART1以依赖于转录及其RS结构域的方式被招募到DSB位点。在促进切除方面，尤其是在G2期的转录相关切除中，SART1与主要的HR因子BRCA1上位性相关。SART1和BRCA1以相互依赖的方式在DSB位点积累，并上位性地抵消由53BP1和RIF1造成的切除阻断。此外，染色体分析表明，SART1和BRCA1上位性地抑制了G2期DSB错配修复引起的基因组改变。总的来说，这些结果表明，SART1和BRCA1协同促进G2期转录活跃基因组区域中产生的DSB的切除，从而通过HR促进准确修复，并抑制基因组不稳定。
