Department of Life Sciences, Ulsan National University of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
Center for Genomic Integrity Institute for Basic Science (IBS), UNIST, Ulsan 44919, Republic of Korea.
Nucleic Acids Res. 2021 Jun 4;49(10):5605-5622. doi: 10.1093/nar/gkab311.
Proper activation of DNA repair pathways in response to DNA replication stress is critical for maintaining genomic integrity. Due to the complex nature of the replication fork (RF), problems at the RF require multiple proteins, some of which remain unidentified, for resolution. In this study, we identified the N-methyl-D-aspartate receptor synaptonuclear signaling and neuronal migration factor (NSMF) as a key replication stress response factor that is important for ataxia telangiectasia and Rad3-related protein (ATR) activation. NSMF localizes rapidly to stalled RFs and acts as a scaffold to modulate replication protein A (RPA) complex formation with cell division cycle 5-like (CDC5L) and ATR/ATR-interacting protein (ATRIP). Depletion of NSMF compromised phosphorylation and ubiquitination of RPA2 and the ATR signaling cascade, resulting in genomic instability at RFs under DNA replication stress. Consistently, NSMF knockout mice exhibited increased genomic instability and hypersensitivity to genotoxic stress. NSMF deficiency in human and mouse cells also caused increased chromosomal instability. Collectively, these findings demonstrate that NSMF regulates the ATR pathway and the replication stress response network for genome maintenance and cell survival.
适当激活 DNA 修复途径以响应 DNA 复制应激对于维持基因组完整性至关重要。由于复制叉 (RF) 的复杂性，RF 处的问题需要多种蛋白质来解决，其中一些仍未被识别。在这项研究中，我们将 N-甲基-D-天冬氨酸受体突触核信号和神经元迁移因子 (NSMF) 鉴定为关键的复制应激反应因子，它对共济失调毛细血管扩张症和 Rad3 相关蛋白 (ATR) 的激活很重要。NSMF 快速定位到停滞的 RF，并作为支架调节复制蛋白 A (RPA) 与细胞分裂周期 5 样 (CDC5L) 和 ATR/ATR 相互作用蛋白 (ATRIP) 的复合物形成。NSMF 的耗竭会损害 RPA2 的磷酸化和泛素化以及 ATR 信号级联反应，导致 RF 在 DNA 复制应激下的基因组不稳定。一致地，NSMF 敲除小鼠表现出增加的基因组不稳定性和对遗传毒性应激的敏感性。人和小鼠细胞中 NSMF 的缺乏也会导致染色体不稳定性增加。总之，这些发现表明 NSMF 调节 ATR 途径和复制应激反应网络，以维持基因组和细胞存活。
