The sensitivity of Cockayne's syndrome cells to DNA-damaging agents is not due to defective transcription-coupled repair of active genes
The sensitivity of Cockayne's syndrome cells to DNA-damaging agents is not due to defective transcription-coupled repair of active genes
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科凯恩综合征细胞对 DNA 损伤剂的敏感性并不是由于活性基因的转录偶联修复缺陷所致
DOI：
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发表时间：
1996
影响因子：
5.3
通讯作者：
L. Mullenders
中科院分区：
文献类型：
--
作者：
M. V. Oosterwijk;A. Versteeg;R. Filon;A. A. Zeeland;L. Mullenders
Cockayne综合征（CS）的两个标志是细胞对UV光的超敏反应和细胞暴露于UV光后合成RNA能力的恢复不足，尽管在整个基因组水平上具有正常的修复能力。长期抑制RNA合成已被归因于转录偶联修复的缺陷，导致从活性基因的转录链缓慢去除DNA损伤。该模型预测CS细胞对另一种DNA损伤剂，即，UV模拟剂N-乙酰氧基-2-乙酰氨基芴（NA-AAF）也应该与RNA合成恢复的缺乏和NA-AAF诱导的DNA加合物的有缺陷的转录偶联修复有关。我们通过测量原代正常人成纤维细胞和两种CS（互补组A和B）成纤维细胞株腺苷脱氨酶基因中DNA加合物的切除率来测试这一点。DNA加合物的高效液相色谱分析表明，N-（脱氧鸟苷-8-基）-2-氨基芴（dG-C8-AF）是NA-AAF在正常和CS细胞中诱导的主要加合物。正常和CS细胞之间没有发现差异，无论是在基因组整体水平或在基因水平上诱导这种病变。此外，在正常和CS细胞中，活性腺苷脱氨酶基因中的dG-C8-AF的修复以相似的速率发生，并且没有链特异性，表明转录偶联修复对活性基因中的dG-C8-AF的修复没有显著贡献。然而，CS细胞对NA-AAF的敏感性是正常细胞的三倍，并且无法恢复合成RNA的能力。我们的数据排除了有缺陷的转录偶联修复作为CS细胞对DNA损伤剂的敏感性增加的原因，并表明细胞的敏感性和长期抑制的RNA合成主要是由于转录缺陷。我们假设，在用UV或NA-AAF处理细胞后，基础转录因子TFIIH参与核苷酸切除修复，并且CS基因产物参与TFIIH转换回转录功能。在这种观点中，CS蛋白充当修复-转录解偶联因子。如果解偶联过程有缺陷，RNA合成将受到抑制，导致细胞敏感性。由于转录对于转录偶联修复是必不可少的，CS缺陷将影响那些修复主要是转录偶联的病变，即，UV诱导的环丁烷嘧啶二聚体。
Two of the hallmarks of Cockayne's syndrome (CS) are the hypersensitivity of cells to UV light and the lack of recovery of the ability to synthesize RNA following exposure of cells to UV light, in spite of the normal repair capacity at the overall genome level. The prolonged repressed RNA synthesis has been attributed to a defect in transcription-coupled repair, resulting in slow removal of DNA lesions from the transcribed strand of active genes. This model predicts that the sensitivity of CS cells to another DNA-damaging agent, i.e., the UV-mimetic agent N-acetoxy-2-acetylaminofluorene (NA-AAF), should also be associated with a lack of resumption of RNA synthesis and defective transcription-coupled repair of NA-AAF-induced DNA adducts. We tested this by measuring the rate of excision of DNA adducts in the adenosine deaminase gene of primary normal human fibroblasts and two CS (complementation group A and B) fibroblast strains. High-performance liquid chromatography analysis of DNA adducts revealed that N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-C8-AF) was the main adduct induced by NA-AAF in both normal and CS cells. No differences were found between normal and CS cells with respect to induction of this lesion either at the level of the genome overall or at the gene level. Moreover, repair of dG-C8-AF in the active adenosine deaminase gene occurred at similar rates and without strand specificity in normal and CS cells, indicating that transcription-coupled repair does not contribute significantly to repair of dG-C8-AF in active genes. Yet CS cells are threefold more sensitive to NA-AAF than are normal cells and are unable to recover the ability to synthesize RNA. Our data rule out defective transcription-coupled repair as the cause of the increased sensitivity of CS cells to DNA-damaging agents and suggest that the cellular sensitivity and the prolonged repressed RNA synthesis are primarily due to a transcription defect. We hypothesize that upon treatment of cells with either UV or NA-AAF, the basal transcription factor TFIIH becomes involved in nucleotide excision repair and that the CS gene products are involved in the conversion of TFIIH back to the transcription function. In this view, the CS proteins act as repair-transcription uncoupling factors. If the uncoupling process is defective, RNA synthesis will stay repressed, causing cellular sensitivity. Since transcription is essential for transcription-coupled repair, the CS defect will affect those lesions whose repair is predominantly transcription coupled, i.e., UV-induced cyclobutane pyrimidine dimers.
来自着色性干皮病互补组 C 的紫外线照射细胞中特定染色质结构域的选择性修复。
DOI：
10.1016/0921-8777(90)90071-c
发表时间：
1990
期刊：
Mutation research
影响因子：
--
作者：
Kantor,GJ;Barsalou,LS;Hanawalt,PC
通讯作者：
Hanawalt,PC
人腺苷脱氨酶基因的细胞类型特异性转录调控。
影响因子：
14.9
作者：
Lattier,DL;States,JC;Hutton,JJ;Wiginton,DA
通讯作者：
Wiginton,DA
使用 UVRABC 核酸酶对哺乳动物细胞中确定的 DNA 序列中氨基芴加合物的形成和修复进行定量。
DOI：
--
发表时间：
1989
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Tang,MS;Bohr,VA;Zhang,XS;Pierce,J;Hanawalt,PC
通讯作者：
Hanawalt,PC