A new connection of mRNP biogenesis and export with transcription-coupled repair
A new connection of mRNP biogenesis and export with transcription-coupled repair
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DOI：
10.1093/nar/gkm373
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发表时间：
2007-06-01
影响因子：
14.9
通讯作者：
Aguilera, Andres
中科院分区：
文献类型：
--
作者：
Gaillard, Helene;Wellinger, Ralf Erik;Aguilera, Andres
尽管在活性基因的转录链中DNA修复速度更快，但人们对mRNP的生物发生和输出在转录偶联修复(TCR)中的可能贡献知之甚少。有趣的是，最近发现THO的突变株在核苷酸切除修复方面存在缺陷。THO是一种参与维持基因组完整性、mRNP生物发生和输出的转录复合体。在本研究中，我们通过分子DNA修复分析表明，酵母中高效的TCR需要两个主要的mRNA输出复合体Sub2-Yra1和Thp1-Sac3。仔细的分析表明，突变体在TCR中也受到特定的影响。核酶介导的两个紫外线损伤热点之间的mRNA自我切割表明，有效的TCR不依赖于新生的mRNA，无论是在野生型还是在突变的细胞中。随着严重的紫外线损伤依赖的处理能力的丧失，RNAPII在紫外线照射下被发现与染色质结合，这表明RNAPII在DNA损伤处仍然停滞不前。此外，def1，一个负责降解停滞的RNAPII的因子，似乎对遭受DNA损伤的突变体的生存至关重要。我们的结果表明，RNAPII在mRNP生物发生和输出突变方面并不擅长TCR，这为我们对真核细胞中TCR的了解打开了新的视角。
Although DNA repair is faster in the transcribed strand of active genes, little is known about the possible contribution of mRNP biogenesis and export in transcription-coupled repair (TCR). Interestingly, mutants of THO, a transcription complex involved in maintenance of genome integrity, mRNP biogenesis and export, were recently found to be deficient in nucleotide excision repair. In this study we show by molecular DNA repair analysis, that Sub2-Yra1 and Thp1-Sac3, two main mRNA export complexes, are required for efficient TCR in yeast. Careful analysis revealed that THO mutants are also specifically affected in TCR. Ribozyme-mediated mRNA self-cleavage between two hot spots for UV damage showed that efficient TCR does not depend on the nascent mRNA, neither in wild-type nor in mutant cells. Along with severe UV damage-dependent loss in processivity, RNAPII was found binding to chromatin upon UV irradiation in THO mutants, suggesting that RNAPII remains stalled at DNA lesions. Furthermore, Def1, a factor responsible for the degradation of stalled RNAPII, appears essential for the viability of THO mutants subjected to DNA damage. Our results indicate that RNAPII is not proficient for TCR in mRNP biogenesis and export mutants, opening new perspectives on our knowledge of TCR in eukaryotic cells.