Jones Rebecca M, Ruiz Joaquin Herrero, Scaramuzza Shaun, Nath Sarmi, Liu Chaoyu, Henklewska Marta, Natsume Toyoaki, Bristow Robert G, Romero Francisco, Kanemaki Masato T, Gambus Agnieszka
Institute of Cancer and Genomic Sciences, Birmingham Centre for Genome Biology, University of Birmingham, Birmingham, UK.
Department of Genetics, The Graduate University for Advanced Studies (SOKENDAI), Mishima, Shizuoka, Japan.
iScience. 2024 Jun 12;27(7):110260. doi: 10.1016/j.isci.2024.110260. eCollection 2024 Jul 19.
To ensure timely duplication of the entire eukaryotic genome, thousands of replication machineries (replisomes) act on genomic DNA at any time during S phase. In the final stages of this process, replisomes are unloaded from chromatin. Unloading is driven by polyubiquitylation of MCM7, a subunit of the terminated replicative helicase, and processed by p97/VCP segregase. Most of our knowledge of replication termination comes from model organisms, and little is known about how this process is executed and regulated in human somatic cells. Here we show that replisome disassembly in this system requires CUL2-driven MCM7 ubiquitylation, p97, and UBXN7 for unloading and provide evidence for "backup" mitotic replisome disassembly, demonstrating conservation of such mechanisms. Finally, we find that small-molecule inhibitors against Cullin ubiquitin ligases (CULi) and p97 (p97i) affect replisome unloading but also lead to induction of replication stress in cells, which limits their usefulness to specifically target replisome disassembly processes.
为确保真核生物基因组的及时复制，在S期的任何时候，数以千计的复制机器（复制体）作用于基因组DNA。在这一过程的最后阶段，复制体从染色质上卸载。卸载由终止复制解旋酶的一个亚基MCM7的多聚泛素化驱动，并由p97/VCP分离酶进行处理。我们对复制终止的了解大多来自模式生物，而对于这一过程在人类体细胞中是如何执行和调控的却知之甚少。在这里，我们表明该系统中的复制体拆卸需要CUL2驱动的MCM7泛素化、p97和UBXN7进行卸载，并为“备用”有丝分裂复制体拆卸提供了证据，证明了此类机制的保守性。最后，我们发现针对Cullin泛素连接酶（CULi）和p97（p97i）的小分子抑制剂会影响复制体卸载，但也会导致细胞中复制应激的诱导，这限制了它们对特异性靶向复制体拆卸过程的实用性。
