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哺乳动物端粒中的内核酶独立的LINE-1逆转换
Tammy A Morrish1, José Luis Garcia-Perez, Thomas D Stamato
1Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan 48109-0618, USA. morrisht@jhmi.edu
Nature
|March 9, 2007
概括
长间隔的元素-1 (LINE-1或L1) 逆转移子可以通过内核酶独立的途径集成到功能障碍的端粒中. 这表明L1逆转换可能是一种古老的DNA修复机制.
科学领域:
- 遗传学 遗传学 是一个
- 分子生物学分子生物学
- 基因组学就是基因组学.
背景情况:
- 长间隔元素-1 (LINE-1或L1) 是丰富的非LTR反转移体,占人类DNA的17%左右.
- L1元素通过目标位点原始反转录来动员,利用它们的内核酶和反转录酶.
- 在中国仓鼠卵巢 (CHO) 细胞中存在一个与内核酶独立的 (EN(i)) L1逆转移途径,该细胞在非同源端结合 (NHEJ) 中有缺陷.
研究的目的:
- 描述EN(i) 在V3 CHO细胞中具有DNA-PKcs缺乏,功能障碍的端粒和NHEJ缺陷的逆转换事件.
- 研究端粒功能障碍和NHEJ因素在L1逆转换中的作用.
- 探索功能失调的端粒作为缺乏内核酶活性的L1元素的整合点的潜力.
主要方法:
- 在V3 CHO细胞和控制XR-1 CHO细胞中生成和分析EN(i) 逆转换事件.
- 评估与端粒重复 (5'-TTAGGG-3') 相关的端粒相关插入.
- 在XR-1细胞中利用主导负TRF2等位基因的短暂表达来破坏端粒封闭.
主要成果:
- 在V3 CHO细胞中,大约30%的EN(i) 逆转换事件被插入到完美端粒的旁边,以特定的方向重复.
- 在对照细胞或XRCC4缺乏XR-1细胞中没有观察到类似的端粒相关插入.
- 通过主导负的TRF2表达来破坏端粒封闭,使得XR-1细胞中的端粒关联EN (i) 逆转换成为可能.
结论:
- 具有禁用内核酶活性的L1元素可以利用功能障碍的端粒作为集成基质.
- 逆转换与端粒酶具有机理上的相似性,它使用3'OH在DNA损伤或染色体末端进行原始化.
- (i) 逆转移可能代表一种古老的RNA介导的DNA修复机制,在非LTR逆转移子中早于内核酶获取.
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