DNA-Directed Polymerase Subunits Play a Vital Role in Human Telomeric Overhang Processing.
DNA-Directed Polymerase Subunits Play a Vital Role in Human Telomeric Overhang Processing.
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DOI：
10.1158/1541-7786.mcr-14-0381
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发表时间：
2015-03
期刊：
影响因子：
--
通讯作者：
Loayza D
中科院分区：
文献类型：
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作者：
Diotti R;Kalan S;Matveyenko A;Loayza D
端粒由TTAGGG重复序列组成，由庇护蛋白复合物结合，并以3'悬垂结束。在人类中，端粒在每次细胞分裂时都会缩短，除非端粒酶（TERT）被表达并能够增加端粒重复序列。为了有效地维持端粒，必须合成与端粒酶合成的DNA互补链。最近的研究发现，在细胞周期的s期，为了改变适当的悬垂，处理端粒所必需的不同活动之间存在联系。值得注意的是，已知与聚合酶复合物（POLA/引物酶）功能相互作用的人类CST复合物（CTC1/STN1/TEN1）在端粒加工中起重要作用。本研究的重点是聚合酶的催化亚基（POLA1/p180）和辅助亚基（POLA2/p68）及其在端粒中的机制作用。我们使用染色质免疫沉淀（ChIP）技术检测了s期端粒的p68和p180。我们还可以证明CST，庇护蛋白和聚合酶复合物相互作用，揭示端粒上发生的接触。我们发现聚合酶复合物可能与端粒酶活性有关。最后，siRNA对p180的耗竭导致端粒中过量p180的增加。这些数据支持一个模型，在该模型中，聚合酶复合物对于通过填充合成在s期进行适当的端粒悬垂处理是重要的。这些结果揭示了有效的端粒维持和保护所必需的重要事件。
Telomeres consist of TTAGGG repeats bound by the shelterin complex and end with a 3' overhang. In humans, telomeres shorten at each cell division, unless telomerase (TERT) is expressed and able to add telomeric repeats. For effective telomere maintenance, the DNA strand complementary to that made by telomerase must be synthesized. Recent studies have discovered a link between different activities necessary to process telomeres in the S-phase of the cell cycle in order to reform a proper overhang. Notably, the human CST complex (CTC1/STN1/TEN1), known to interact functionally with the polymerase complex (POLA/primase), was shown to be important for telomere processing. Here, focus was paid to the catalytic (POLA1/p180) and accessory (POLA2/p68) subunits of the polymerase, and their mechanistic roles at telomeres. We were able to detect p68 and p180 at telomeres in S-phase using chromatin immunoprecipitation (ChIP). We could also show that the CST, shelterin and polymerase complexes interact, revealing contacts occurring at telomeres. We found that the polymerase complex could associate with telomerase activity. Finally, depletion of p180 by siRNA led to increased overhang amounts at telomeres. These data support a model in which the polymerase complex is important for proper telomeric overhang processing through fill-in synthesis, during S-phase. These results shed light on important events necessary for efficient telomere maintenance and protection.