Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Roosevelt Drive, Oxford, OX3 7DQ, UK.
Institute of Biochemistry and Molecular Biology, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
Nat Commun. 2019 Jul 17;10(1):3142. doi: 10.1038/s41467-019-11095-y.
The SPRTN metalloprotease is essential for DNA-protein crosslink (DPC) repair and DNA replication in vertebrate cells. Cells deficient in SPRTN protease exhibit DPC-induced replication stress and genome instability, manifesting as premature ageing and liver cancer. Here, we provide a body of evidence suggesting that SPRTN activates the ATR-CHK1 phosphorylation signalling cascade during physiological DNA replication by proteolysis-dependent eviction of CHK1 from replicative chromatin. During this process, SPRTN proteolyses the C-terminal/inhibitory part of CHK1, liberating N-terminal CHK1 kinase active fragments. Simultaneously, CHK1 full length and its N-terminal fragments phosphorylate SPRTN at the C-terminal regulatory domain, which stimulates SPRTN recruitment to chromatin to promote unperturbed DNA replication fork progression and DPC repair. Our data suggest that a SPRTN-CHK1 cross-activation loop plays a part in DNA replication and protection from DNA replication stress. Finally, our results with purified components of this pathway further support the proposed model of a SPRTN-CHK1 cross-activation loop.
SPRTN 金属蛋白酶对于脊椎动物细胞中的 DNA-蛋白质交联 (DPC) 修复和 DNA 复制至关重要。缺乏 SPRTN 蛋白酶的细胞表现出 DPC 诱导的复制应激和基因组不稳定性，表现为过早衰老和肝癌。在这里，我们提供了一系列证据表明，SPRTN 通过依赖于蛋白水解的从复制染色质中逐出 CHK1，来激活生理 DNA 复制过程中的 ATR-CHK1 磷酸化信号级联。在这个过程中，SPRTN 蛋白水解 CHK1 的 C 端/抑制部分，释放 N 端 CHK1 激酶活性片段。同时，全长 CHK1 和其 N 端片段在 C 端调节域磷酸化 SPRTN，这刺激 SPRTN 募集到染色质，以促进未受干扰的 DNA 复制叉进展和 DPC 修复。我们的数据表明，SPRTN-CHK1 交叉激活环在 DNA 复制和防止 DNA 复制应激中起作用。最后，我们用该途径的纯化成分进行的实验进一步支持了 SPRTN-CHK1 交叉激活环的模型。
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