Roumen Tsanev Institute of Molecular Biology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. 21, 1113, Sofia, Bulgaria.
Department of Biochemistry and Molecular Biology, University College London, London WC1E 6BT, UK.
Int J Biochem Cell Biol. 2020 Nov;128:105839. doi: 10.1016/j.biocel.2020.105839. Epub 2020 Aug 23.
Chromatin regulators control transcription and replication, however if and how they might influence the coordination of these processes still is largely unknown. RUVBL1 and the related ATPase RUVBL2 participate in multiple nuclear processes and are implicated in cancer. Here, we report that both the excess and the deficit of the chromatin regulator RUVBL1 impede DNA replication as a consequence of altered transcription. Surprisingly, cells that either overexpressed or were silenced for RUVBL1 had slower replication fork rates and accumulated phosphorylated H2AX, dependent on active transcription. However, the mechanisms of transcription-dependent replication stress were different when RUVBL1 was overexpressed and when depleted. RUVBL1 overexpression led to increased c-Myc-dependent pause release of RNAPII, as evidenced by higher overall transcription, much stronger Ser2 phosphorylation of Rpb1- C-terminal domain, and enhanced colocalization of Rpb1 and c-Myc. RUVBL1 deficiency resulted in increased ubiquitination of Rpb1 and reduced mobility of an RNAP subunit, suggesting accumulation of stalled RNAPIIs on chromatin. Overall, our data show that by modulating the state of RNAPII complexes, RUVBL1 deregulation induces replication-transcription interference and compromises genome integrity during S-phase.
染色质调控因子控制转录和复制，然而，它们是否以及如何影响这些过程的协调仍然很大程度上未知。RUVBL1 和相关的 ATP 酶 RUVBL2 参与多种核过程，并与癌症有关。在这里，我们报告说，染色质调控因子 RUVBL1 的过剩和不足都会由于转录改变而阻碍 DNA 复制。令人惊讶的是，过度表达或沉默 RUVBL1 的细胞复制叉速率较慢，并积累磷酸化的 H2AX，这依赖于活跃的转录。然而，当 RUVBL1 过表达和耗尽时，转录依赖性复制应激的机制是不同的。RUVBL1 过表达导致 c-Myc 依赖性暂停释放的 RNA 聚合酶 II 增加，这表现为总转录增加，Rpb1- C 末端结构域的 Ser2 磷酸化更强，以及 Rpb1 和 c-Myc 的共定位增强。RUVBL1 缺乏导致 Rpb1 的泛素化增加和 RNA 聚合酶亚基的迁移率降低，表明在染色质上停滞的 RNA 聚合酶 II 的积累。总的来说，我们的数据表明，通过调节 RNA 聚合酶 II 复合物的状态，RUVBL1 失调在 S 期诱导复制-转录干扰并损害基因组完整性。
