Human RAP1 specifically protects telomeres of senescent cells from DNA damage
Human RAP1 specifically protects telomeres of senescent cells from DNA damage
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人类 RAP1 特异性保护衰老细胞的端粒免受 DNA 损伤
DOI：
10.15252/embr.201949076
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发表时间：
2020-02-25
期刊：
影响因子：
7.7
通讯作者：
Mendez-Bermudez, Aaron
中科院分区：
文献类型：
--
作者：
Lototska, Liudmyla;Yue, Jia-Xing;Mendez-Bermudez, Aaron
阻遏物/激活蛋白1（RAP 1）是在端粒中发现的高度进化保守的蛋白质。尽管酵母Rap 1是防止非同源末端连接（NHEJ）并因此防止端粒融合的关键端粒加帽蛋白，但其在哺乳动物体内端粒中的作用仍然存在争议。在这里，我们证明，RAP 1是需要保护端粒在复制衰老的人类细胞。在这些细胞中，但不是在年轻或分裂的衰老前细胞中，RAP 1的下调，导致端粒脱帽和融合。在HeLa细胞系中进一步探索了RAP 1的抗融合作用，其中通过诱导型CRISPR/Cas9策略耗尽了RAP 1表达。这些细胞中RAP 1的缺失仅在端粒酶被抑制时才引起端粒融合。我们进一步表明，由RAP 1损失触发的融合依赖于DNA连接酶IV。我们的结论是，人类RAP 1是专门参与保护关键短端粒。这对衰老细胞中端粒的功能具有重要意义。
Repressor/activator protein 1 (RAP1) is a highly evolutionarily conserved protein found at telomeres. Although yeast Rap1 is a key telomere capping protein preventing non-homologous end joining (NHEJ) and consequently telomere fusions, its role at mammalian telomeres in vivo is still controversial. Here, we demonstrate that RAP1 is required to protect telomeres in replicative senescent human cells. Downregulation of RAP1 in these cells, but not in young or dividing pre-senescent cells, leads to telomere uncapping and fusions. The anti-fusion effect of RAP1 was further explored in a HeLa cell line where RAP1 expression was depleted through an inducible CRISPR/Cas9 strategy. Depletion of RAP1 in these cells gives rise to telomere fusions only when telomerase is inhibited. We further show that the fusions triggered by RAP1 loss are dependent upon DNA ligase IV. We conclude that human RAP1 is specifically involved in protecting critically short telomeres. This has important implications for the functions of telomeres in senescent cells.