A kinase-independent role for the Rad3(ATR)-Rad26(ATRIP) complex in recruitment of Tel1(ATM) to telomeres in fission yeast.
A kinase-independent role for the Rad3(ATR)-Rad26(ATRIP) complex in recruitment of Tel1(ATM) to telomeres in fission yeast.
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DOI：
10.1371/journal.pgen.1000839
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发表时间：
2010-02-05
期刊：
影响因子：
4.5
通讯作者：
Nakamura TM
中科院分区：
文献类型：
--
作者：
Subramanian L;Nakamura TM
ATM和ATR是真核生物端粒稳定维持所必需的两个冗余检查点激酶。先前的研究已经确定MRN （Mre11-Rad50-Nbs1）和ATRIP （ATR相互作用蛋白）分别与ATM和ATR相互作用，并将其伴侣激酶招募到DNA损伤位点。在这里，我们研究了裂变酵母如何调节Tel1ATM和Rad3ATR向端粒的募集。定量染色质免疫沉淀（ChIP）分析意外地显示，MRN复合体也可以独立于先前建立的Nbs1 c端Tel1ATM相互作用域，促进Tel1ATM募集到端粒。在缺乏Nbs1的c端60个氨基酸的Tel1ATM相互作用结构域的nbs1-c60Δ细胞中，Tel1ATM向端粒募集依赖于Rad3ATR- rad26atrip，但Rad3ATR的激酶结构域是不可缺少的。因此，我们的研究结果表明，Rad3ATR- rad26atrip复合体通过与Nbs1的Tel1ATM相互作用域冗余的机制，独立于Rad3ATR激酶活性，参与了Tel1ATM的募集。此外，我们发现Nbs1的n端有助于Rad3ATR-Rad26ATRIP募集到端粒。在复制应激反应中，哺乳动物ATR-ATRIP也通过依赖于MRN复合体但不依赖于Nbs1的c端ATM相互作用域的机制促进ATM激活。由于端粒保护和DNA损伤反应机制在分裂酵母和哺乳动物细胞之间非常保守，哺乳动物ATR - atrip也可能独立于ATR激酶活性，促进ATM向端粒和DNA损伤位点的募集。ATM和ATR激酶是两个进化上保守的DNA损伤传感器，在所有真核细胞中负责维持稳定的基因组。这两种激酶保护真核生物基因组免受不需要的双链DNA断裂（DSBs）和基因组DNA复制过程中的错误。此外，ATM和ATR对于端粒的稳定维持是冗余的，端粒是线性真核染色体末端的保护结构。我们目前在分裂酵母中的研究表明，先前定义的DNA修复蛋白Nbs1的c端Tel1ATM相互作用结构域有助于Tel1ATM向dsb募集，但对于Tel1ATM向端粒募集是必不可少的，因为以前未认识到ATR在Tel1ATM向端粒募集中的激酶独立作用。此外，发现Nbs1的n端对于ATR和ATM向端粒募集至关重要。端粒维持的调节因子最近成为哺乳动物细胞抗肿瘤发生和衰老的潜在重要治疗靶点。由于负责端粒维护和细胞对DNA损伤反应的蛋白质在裂变酵母和哺乳动物细胞之间高度保守，新发现的ATM和ATR之间的分子串扰也可能在哺乳动物细胞的端粒维护和DNA损伤反应中发挥关键作用。
ATM and ATR are two redundant checkpoint kinases essential for the stable maintenance of telomeres in eukaryotes. Previous studies have established that MRN (Mre11-Rad50-Nbs1) and ATRIP (ATR Interacting Protein) interact with ATM and ATR, respectively, and recruit their partner kinases to sites of DNA damage. Here, we investigated how Tel1ATM and Rad3ATR recruitment to telomeres is regulated in fission yeast. Quantitative chromatin immunoprecipitation (ChIP) assays unexpectedly revealed that the MRN complex could also contribute to the recruitment of Tel1ATM to telomeres independently of the previously established Nbs1 C-terminal Tel1ATM interaction domain. Recruitment of Tel1ATM to telomeres in nbs1-c60Δ cells, which lack the C-terminal 60 amino acid Tel1ATM interaction domain of Nbs1, was dependent on Rad3ATR-Rad26ATRIP, but the kinase domain of Rad3ATR was dispensable. Thus, our results establish that the Rad3ATR-Rad26ATRIP complex contributes to the recruitment of Tel1ATM independently of Rad3ATR kinase activity, by a mechanism redundant with the Tel1ATM interaction domain of Nbs1. Furthermore, we found that the N-terminus of Nbs1 contributes to the recruitment of Rad3ATR-Rad26ATRIP to telomeres. In response to replication stress, mammalian ATR–ATRIP also contributes to ATM activation by a mechanism that is dependent on the MRN complex but independent of the C-terminal ATM interaction domain of Nbs1. Since telomere protection and DNA damage response mechanisms are very well conserved between fission yeast and mammalian cells, mammalian ATR–ATRIP may also contribute to the recruitment of ATM to telomeres and to sites of DNA damage independently of ATR kinase activity. ATM and ATR kinases are two evolutionarily conserved sensors of DNA damage, responsible for maintaining stable genomes in all eukaryotic cells. These two kinases safeguard eukaryotic genomes against undesired double-stranded DNA breaks (DSBs) and errors during duplication of genomic DNA. Furthermore, ATM and ATR are redundantly required for stable maintenance of telomeres, protective structures at ends of linear eukaryotic chromosomes. Our current study in fission yeast demonstrates that the previously defined C-terminal Tel1ATM interaction domain of the DNA repair protein Nbs1, which contributes to recruitment of Tel1ATM to DSBs, is dispensable for recruitment of Tel1ATM to telomeres, due to a previously unrecognized kinase-independent role of ATR in recruitment of Tel1ATM to telomeres. Furthermore, the N-terminus of Nbs1 was found to be critical for recruitment of both ATR and ATM to telomeres. Regulators of telomere maintenance have recently emerged as potentially important therapeutic targets against tumorigenesis and aging in mammalian cells. Since proteins responsible for proper maintenance of telomeres and cellular responses to DNA damage are highly conserved between fission yeast and mammalian cells, a newly uncovered molecular crosstalk between ATM and ATR might also play critical roles in telomere maintenance and DNA damage responses in mammalian cells.
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影响因子：
5.3
作者：
Chahwan, C;Nakamura, TM;Rhind, N
通讯作者：
Rhind, N
影响因子：
21.3
作者：
Jazayeri, A;Falck, J;Jackson, SP
通讯作者：
Jackson, SP
影响因子：
15.3
作者：
Cuadrado, M;Martinez-Pastor, B;Fernandez-Capetillo, O
通讯作者：
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影响因子：
4.5
作者：
Moser BA;Subramanian L;Khair L;Chang YT;Nakamura TM
通讯作者：
Nakamura TM
DOI：
10.1073/pnas.0812605106
发表时间：
2009-02-17
影响因子：
11.1
作者：
Gasparyan, Hovik J.;Xu, Ling;Nugent, Constance I.
通讯作者：
Nugent, Constance I.