文章：

MBD1通过招募PARP1并控制转录-复制冲突来保护复制叉稳定性

MBD1 protects replication fork stability by recruiting PARP1 and controlling transcription-replication conflicts 

原文发布日期：2023-11-10 

英文摘要：

The replication-stress response is essential to ensure the faithful transmission of genetic information to daughter cells. Although several stress-resolution pathways have been identified to deal with replication stress, the precise regulatory mechanisms for replication fork stability are not fully understood. Our study identified Methyl-CpG Binding Domain 1 (MBD1) as essential for the maintaining genomic stability and protecting stalled replication forks in mammalian cells. Depletion of MBD1 increases DNA lesions and sensitivity to replication stress. Mechanistically, we found that loss of MBD1 leads to the dissociation of Poly(ADP-ribose) polymerase 1 (PARP1) from the replication fork, potentially accelerating fork progression and resulting in higher levels of transcription-replication conflicts (T-R conflicts). Using a proximity ligation assay combined with 5-ethynyl-2′-deoxyuridine, we revealed that the MBD1 and PARP1 proteins were recruited to stalled forks under hydroxyurea (HU) treatment. In addition, our study showed that the level of R-loops also increased in MBD1-delated cells. Without MBD1, stalled replication forks resulting from T-R conflicts were primarily degraded by the DNA2 nuclease. Our findings shed light on a new aspect of MBD1 in maintaining genome stability and providing insights into the mechanisms underlying replication stress response. 

摘要翻译： 

复制应激反应对于确保遗传信息准确传递至子细胞至关重要。尽管目前已发现多种应激解决通路来处理复制应激，但关于复制叉稳定性的精确调控机制尚未完全阐明。我们的研究发现甲基-CpG结合域蛋白1（MBD1）在维持哺乳动物细胞基因组稳定性和保护停滞复制叉方面具有关键作用。MBD1的缺失会增加DNA损伤并对复制应激更敏感。从机制上讲，我们发现MBD1缺失会导致聚腺苷二磷酸核糖聚合酶1（PARP1）从复制叉解离，这可能加速复制叉进展并导致更高水平的转录-复制冲突（T-R冲突）。通过邻近连接 assays结合5-乙炔基-2'-脱氧尿苷标记技术，我们证实MBD1和PARP1蛋白在羟基脲（HU）处理下被招募至停滞复制叉。此外，研究显示MBD1缺失细胞中R环水平也显著上升。在缺乏MBD1的情况下，由T-R冲突引发的停滞复制叉主要被DNA2核酸酶降解。本研究揭示了MBD1维持基因组稳定性的新机制，为理解复制应激应答的分子基础提供了新见解。

原文链接：

MBD1 protects replication fork stability by recruiting PARP1 and controlling transcription-replication conflicts