端粒通过切断检查点信号传导路径来避免终端检测
Tiago Carneiro1, Lyne Khair, Clara C Reis
1Instituto Gulbenkian de Ciência, Oeiras 2781-901, Portugal.
Nature
|September 11, 2010
概括
端粒通过缺乏特定的表观遗传标记物 (如H4K20me2) 来阻止细胞循环停止,尽管它会招募DNA修复蛋白. 这种染色质特权确保了适当的染色体末端保护,而不会引发DNA损伤反应.
科学领域:
- 分子生物学分子生物学
- 细胞生物学 细胞生物学
- 表观遗传学 在表观遗传学中,表观遗传学是指表观遗传学.
背景情况:
- 端粒保护染色体末端免受DNA损伤的识别.
- 参与DNA修复和检查点的蛋白质被招募到端粒中,但避免了永久性的细胞循环停止.
- 阻止端粒激活DNA损伤反应的机制尚不清楚.
研究的目的:
- 为了研究端粒如何防止DNA损伤反应导致裂变酵母细胞循环停止.
- 为了确定底层的分子机制,端粒特异性染色质调节.
- 了解表观遗传修饰在端粒功能中的作用.
主要方法:
- 对缺少Taz1的裂变酵母 (Schizosaccharomyces pombe) 突变物 (人类TRF1/TRF2的正义物) 的分析.
- 评估了DNA修复蛋白 (Rad22/RAD52,Rhp51/RAD51) 和检查点传感器 (RPA,Rad9,Rad26/ATRIP,Cut5/Rad4/TOPBP1) 对端粒的招募.
- 研究了基因组修饰 (H4K20me2, γH2A) 和端粒结合蛋白 (Pot1, Ccq1) 在检查点激活中的作用.
主要成果:
- 缺乏Taz1的细胞将DNA修复和检查点蛋白招募到端粒中,但未能积累Crb2 (53BP1),因此无法激活Chk1依赖的细胞循环停止.
- 人工招募Crb2 (53BP1) 到taz1Δ端粒诱导一个完整的检查点反应和细胞循环停止.
- 端粒缺乏H4K20me2,这是稳定的Crb2 (53BP1) 关联所需的修饰,与内部染色体区域不同.
- 从端粒中失去Pot1或Ccq1导致Crb2 (53BP1) 焦点,Chk1激活和细胞循环停止.
- 端粒是染色质特权区域,缺乏必要的表观遗传标记,用于DNA损伤反应放大.
结论:
- 裂变酵母端粒在表观遗传上是不同的,缺乏H4K20me2,这阻止了DNA损伤信号的放大.
- 由Pot1和Ccq1调解的Crb2 (53BP1) 从端粒中排除,对于防止细胞循环停止至关重要.
- 这种染色质特权通过防止不适当的检查点激活来确保端粒维护和功能,这对于通过ATM/ATR激酶招募端粒酶至关重要.
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