Cell-cycle-dependent Xenopus TRF1 recruitment to telomere chromatin regulated by Polo-like kinase
Cell-cycle-dependent Xenopus TRF1 recruitment to telomere chromatin regulated by Polo-like kinase
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DOI：
10.1038/sj.emboj.7600964
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发表时间：
2006-02-08
期刊：
影响因子：
11.4
通讯作者：
Ishikawa, F
中科院分区：
文献类型：
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作者：
Nishiyama, A;Muraki, K;Ishikawa, F
端粒受到稳态机制的调节，该机制包括端粒酶和端粒重复序列结合蛋白TRF 1和TRF 2。最近，有人假设端粒以细胞周期依赖的方式呈现不同的构型，尽管缺乏直接的生化证据。在这里，我们表明，非洲爪蟾TRF 1（xTRF 1）协会与端粒染色质特异性有丝分裂非洲爪蟾卵提取物，并从它有丝分裂退出。xTRF 1与染色质的这种细胞周期依赖性缔合需要N-末端TRF-homology（TRFH）结构域和连接TRFH结构域和C-末端Myb结构域的接头区。与此相反，非洲爪蟾TRF 2（xTRF 2）与染色质在整个细胞周期。我们发现Polo样激酶（Plx 1）在体外磷酸化xTRF 1。此外，有丝分裂xTRF 1染色质协会显着受损时，Plx 1免疫耗尽的提取物。最后，与有丝分裂染色质相比，在复制间期染色质中检测到高端粒酶活性。这些结果表明，端粒染色质是积极调控的细胞周期依赖性的过程，并提供了一个见解，了解端粒如何在细胞周期中进行DNA代谢。
Telomeres are regulated by a homeostatic mechanism that includes telomerase and telomeric repeat binding proteins, TRF1 and TRF2. Recently, it has been hypothesized that telomeres assume distinct configurations in a cell-cycle-dependent manner, although direct biochemical evidence is lacking. Here we demonstrated that Xenopus TRF1 (xTRF1) associates with telomere chromatin specifically in mitotic Xenopus egg extracts, and dissociates from it upon mitotic exit. Both the N-terminal TRF-homology (TRFH) domain and the linker region connecting the TRFH domain and the C-terminal Myb domain are required for this cell-cycle-dependent association of xTRF1 with chromatin. In contrast, Xenopus TRF2 (xTRF2) associates with chromatin throughout the cell cycle. We showed that Polo-like kinase (Plx1) phosphorylates xTRF1 in vitro. Moreover, the mitotic xTRF1 - chromatin association was significantly impaired when Plx1 was immunodepleted from the extracts. Finally, high telomerase activities were detected in association with replicating interphase chromatin compared with mitotic chromatin. These results indicate that telomere chromatin is actively regulated by cell-cycle-dependent processes, and provide an insight for understanding how telomeres undergo DNA metabolisms during the cell cycle.