Shanghai Fifth People's Hospital of Fudan University, Shanghai Key Laboratory of Medical Epigenetics, International Co-laboratory of Medical Epigenetics and Metabolism (Ministry of Science and Technology), Institutes of Biomedical Sciences, Fudan University, Shanghai, China.
Department of Microbiology and Molecular Genetics, The Institute for Medical Research Israel-Canada, The Faculty of Medicine, The Hebrew University of Jerusalem, Ein Kerem, Jerusalem, Israel.
Nat Commun. 2024 Aug 17;15(1):7089. doi: 10.1038/s41467-024-51463-x.
Transcription-blocking lesions (TBLs) stall elongating RNA polymerase II (Pol II), which then initiates transcription-coupled repair (TCR) to remove TBLs and allow transcription recovery. In the absence of TCR, eviction of lesion-stalled Pol II is required for alternative pathways to address the damage, but the mechanism is unclear. Using Protein-Associated DNA Damage Sequencing (PADD-seq), this study reveals that the p97-proteasome pathway can evict lesion-stalled Pol II independently of repair. Both TCR and repair-independent eviction require CSA and ubiquitination. However, p97 is dispensable for TCR and Pol II eviction in TCR-proficient cells, highlighting repair's prioritization over repair-independent eviction. Moreover, ubiquitination of RPB1-K1268 is important for both pathways, with USP7's deubiquitinase activity promoting TCR without abolishing repair-independent Pol II release. In summary, this study elucidates the fate of lesion-stalled Pol II, and may shed light on the molecular basis of genetic diseases caused by the defects of TCR genes.
转录阻断性损伤（TBLs）会使正在延伸的 RNA 聚合酶 II（Pol II）停滞，随后 Pol II 会启动转录偶联修复（TCR）以移除 TBLs 并允许转录恢复。如果没有 TCR，就需要替代途径来移除损伤部位停滞的 Pol II，但机制尚不清楚。本研究利用蛋白关联 DNA 损伤测序（PADD-seq）发现，p97-蛋白酶体途径可以在不依赖修复的情况下将损伤部位停滞的 Pol II 驱逐。TCR 和非修复依赖性驱逐都需要 CSA 和泛素化。然而，p97 在 TCR 功能正常的细胞中对于 TCR 和 Pol II 的驱逐是可有可无的，这凸显了修复相对于非修复依赖性驱逐的优先级。此外，RPB1-K1268 的泛素化对于这两种途径都很重要，USP7 的去泛素酶活性促进了 TCR，而不会完全阻止非修复依赖性 Pol II 的释放。总之，本研究阐明了损伤部位停滞的 Pol II 的命运，并可能为 TCR 基因缺陷导致的遗传疾病的分子基础提供线索。
