CTCF编排了远程凝聚力驱动的V(D) J重组扫描
Zhaoqing Ba1,2, Jiangman Lou3,4, Adam Yongxin Ye3,4
1Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, MA, USA. zhaoqing.ba@childrens.harvard.edu.
Nature
|July 28, 2020
概括
在V(D) J重组过程中,CTCF结合阻碍了RAG扫描. 删除CTCF使RAG能够访问远端V(D) S段,促进原生B细胞的高效V(D) J重组.
科学领域:
- 免疫学
- 分子生物学
- 遗传学
背景情况:
- RAG内核酶在 B 细胞中启动 V ((D) J 重组,这是适应性免疫的关键过程.
- RAG扫描,可能由凝聚素辅助,定位用于重组的DNA段,但CTCF结合的元素可以阻碍这一过程.
- 据认为,距离V(H) 段的利用依赖于位点收缩和扩散进入重组中心.
研究的目的:
- 调查线性RAG扫描在远程V (H) 段使用中的作用.
- 确定凝聚素和CTCF对RAG扫描和V-H-DJ-H连接在G1捕获的亲B细胞的影响.
- 探索调节CTCF活动如何影响IGH位点的可访问性和重组.
主要方法:
- 使用辅酶诱导系统来降解G1被捕的v-Abl亲B细胞系中的RAD21 (凝聚素成分) 或CTCF.
- 在蛋白质降解后评估V(D) J重组效率和色素相互作用.
- 操纵细胞中的重组模式与"局部收缩"初级亲B细胞的重组模式进行比较.
主要成果:
- 除了扩散介导的DQ52到JH连接,RAD21降解取消了V(D) J重组和RAG扫描相互作用.
- CTCF降解抑制了与CTCF结合的元素相互作用,但显著促进了远端V(H) 段的重组和相互作用.
- 在CTCF降解后的重组模式模仿了局部收缩的初级pro- B细胞中观察到的模式.
结论:
- 凝聚素介导的RAG扫描对于V(D) J重组至关重要.
- CTCF作为RAG扫描的障碍,防止访问远端V(H) 段.
- 下调 CTCF 便于在 Igh 位点进行凝聚力驱动的 RAG 扫描,促进远端 V ((H) 使用.
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