THO and TRAMP complexes prevent transcription-replication conflicts, DNA breaks, and CAG repeat contractions.
THO and TRAMP complexes prevent transcription-replication conflicts, DNA breaks, and CAG repeat contractions.
复制标题
THO 和 TRAMP 复合物可防止转录复制冲突、DNA 断裂和 CAG 重复收缩。
DOI：
10.1101/2022.03.22.4853861
复制
发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Catherine H. Freudenreich
中科院分区：
文献类型：
--
作者：
Rebecca E. Brown;Xiaofeng A. Su;Stacey Fair;Katherine Wu;Lauren Verra;Robyn Jong;Kristin Andrykovich;Catherine H. Freudenreich
结构形成CAG/CTG重复序列的扩展是几种神经退行性疾病的原因，重复序列的删除是一种潜在的治疗策略。已知转录相关机制可导致CAG重复不稳定性。在这项研究中，我们发现Thp2（一种RNA输出因子，也是THO复合体的成员）和Trf4（一种参与核RNA降解的TRAMP复合体的关键成分）是防止aS中CAG易碎性和重复收缩所必需的。cerevisiaemodel系统。Thp2和Trf4蛋白的缺失导致CAG重复脆性的高度协同增加，表明THO和TRAMP复合物在防止基因组不稳定方面具有互补作用。Thp2或Trf4的缺失会导致CAG重复位点的RNA聚合酶停滞和全基因组转录复制冲突（TRCs）的增加，这意味着转录延伸的损伤是CAG缺乏脆弱性和不稳定性的原因。分析RNase H1过表达对CAG易碎性和TRCs的影响表明，共转录r环是thethp2Δmutants中CAG易碎性的主要原因。相比之下，thetrf4Δmutant中的CAG易碎性和TRCs可以通过RPA过表达来补偿，这表明TRAMP4突变体中过量的未加工RNA导致RPA可用性降低和TRCs水平升高。我们的研究结果表明，RNA监测途径在防止RNAPII失速、TRCs和DNA断裂中的重要性，并表明RNA输出和RNA衰变因子协同工作以维持基因组的稳定性。
Expansion of structure-forming CAG/CTG repetitive sequences is the cause of several neurodegenerative disorders and deletion of repeats is a potential therapeutic strategy. Transcription-associated mechanisms are known to cause CAG repeat instability. In this study, we discovered that Thp2, an RNA export factor and member of the THO complex, and Trf4, a key component of the TRAMP complex involved in nuclear RNA degradation, are necessary to prevent CAG fragility and repeat contractions in aS. cerevisiaemodel system. Depletion of both Thp2 and Trf4 proteins causes a highly synergistic increase in CAG repeat fragility, indicating a complementary role of the THO and TRAMP complexes in preventing genome instability. Loss of either Thp2 or Trf4 causes an increase in RNA polymerase stalling at the CAG repeats and genome-wide transcription-replication conflicts (TRCs), implicating impairment of transcription elongation as a cause of CAG fragility and instability in their absence. Analysis of the effect of RNase H1 overexpression on CAG fragility and TRCs suggests that co-transcriptional R-loops are the main cause of CAG fragility in thethp2Δmutants. In contrast, CAG fragility and TRCs in thetrf4Δmutant can be compensated for by RPA overexpression, suggesting that excess unprocessed RNA in TRAMP4 mutants leads to reduced RPA availability and high levels of TRCs. Our results show the importance of RNA surveillance pathways in preventing RNAPII stalling, TRCs, and DNA breaks, and show that RNA export and RNA decay factors work collaboratively to maintain genome stability.