在模板DNA链中未修复的基切除修复中间体会触发复制叉的崩和PARP抑制剂敏感度
Almudena Serrano-Benitez1,2, Sophie E Wells3, Lylah Drummond-Clarke3
1Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK.
The EMBO journal
|July 26, 2023
概括
在复制分叉之前存在时,DNA单链断裂 (SSB) 会导致染色体断裂. 这发生在SSB修复缺陷细胞中,用5 - - 2'-脱氧氨 (CldU) 治疗,这表明临床效用.
科学领域:
- 分子生物学分子生物学
- 遗传学 是一个遗传学.
- 细胞生物学 细胞生物学
背景情况:
- 单链DNA断裂 (SSBs) 是关键的病变,可以导致复制压力和基因组不稳定性.
- 通过SSB诱导染色体破裂的精确机制,特别是它们相对于复制叉的位置,仍然不完全理解.
研究的目的:
- 为了调查SSB位于复制分叉后面或前面的SSB是否诱导染色体破裂.
- 阐明 uracil DNA glycosylase (UNG) 和 5-chloro-2 -deoxyuridine (CldU) 在 SSB 诱导的 DNA 损伤和细胞毒性的作用.
主要方法:
- 使用的SSB修复缺陷的人类细胞 (缺乏PARP或XRCC1) 对CldU的增强敏感性.
- 在CldU治疗后评估染色体破裂,姐妹染色体交换和细胞毒性.
- 研究了 uracil DNA glycosylase (UNG) 活性在 S 阶段的作用.
主要成果:
- 在SSB修复缺陷细胞中,CldU治疗诱导了染色体破裂,姐妹染色体交换和细胞毒性.
- 观察到的DNA损伤和细胞毒性取决于S相UNG活性.
- 在模板DNA中存在时,CldU的纳入仅在随后的细胞周期中具有细胞毒性,特别是当UNG诱导的SSB在复制分叉之前的模板链中发生时.
- 具有BRCA缺陷的细胞对单独或与PARP抑制剂一起的CldU表现出过敏.
结论:
- 复制叉前面的SSB,而不是它们后面的SSB,是复制叉崩和染色体破裂的主要触发因素.
- 由CldU诱导的DNA损伤和细胞毒性是由UNG在模板DNA链上的活性介导的.
- BRCA缺陷细胞对CldU的过敏性表明CldU的潜在临床应用,可能与PARP抑制剂结合,用于癌症治疗.
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