Transcription Associated Genome Instability Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK.
Lysine Methylation and DNA Damage Laboratory, Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham B15 2TT, UK.
Cell Rep. 2021 Feb 16;34(7):108759. doi: 10.1016/j.celrep.2021.108759.
As transcription and replication use DNA as substrate, conflicts between transcription and replication can occur, leading to genome instability with direct consequences for human health. To determine how the two processes are coordinated throughout S phase, we characterize both processes together at high resolution. We find that transcription occurs during DNA replication, with transcription start sites (TSSs) not fully replicated along with surrounding regions and remaining under-replicated until late in the cell cycle. TSSs undergo completion of DNA replication specifically when cells enter mitosis, when RNA polymerase II is removed. Intriguingly, G2/M DNA synthesis occurs at high frequency in unperturbed cell culture, but it is not associated with increased DNA damage and is fundamentally separated from mitotic DNA synthesis. TSSs duplicated in G2/M are characterized by a series of specific features, including high levels of antisense transcription, making them difficult to duplicate during S phase.
由于转录和复制都以 DNA 作为底物，因此转录和复制之间可能会发生冲突，从而导致基因组不稳定，直接影响人类健康。为了确定这两个过程在 S 期是如何协调的，我们以高分辨率同时对这两个过程进行了表征。我们发现，转录发生在 DNA 复制过程中，转录起始位点 (TSS) 并没有与周围区域一起完全复制，并且在细胞周期的后期仍然处于复制不足的状态。TSS 仅在细胞进入有丝分裂时，即 RNA 聚合酶 II 被去除时，才会完成 DNA 复制。有趣的是，在未受干扰的细胞培养中，G2/M 期的 DNA 合成会高频发生，但它与增加的 DNA 损伤无关，并且与有丝分裂 DNA 合成在本质上是分离的。在 G2/M 期复制的 TSS 具有一系列特定的特征，包括高水平的反义转录，这使得它们在 S 期很难复制。
