TRF2-Tethered TIN2 Can Mediate Telomere Protection by TPP1/POT1
TRF2-Tethered TIN2 Can Mediate Telomere Protection by TPP1/POT1
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DOI：
10.1128/mcb.01052-13
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发表时间：
2014-04-01
影响因子：
5.3
通讯作者：
de lange, Titia
中科院分区：
文献类型：
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作者：
Frescas, David;de lange, Titia
庇护蛋白TIN 2是TPP 1/POT 1异源二聚体的端粒积累和POT 1蛋白（小鼠中的POT 1a和POT 1b）保护端粒所必需的。TIN 2还与TRF 1和TRF 2结合，改善TRF 2的端粒定位及其功能。在这里，我们问TIN 2是否需要与TRF 1和TRF 2相互作用来介导TRF 2和POT 1a/B提供的端粒保护。使用TRF 1结合缺陷的TIN 2等位基因（TIN 2-L247 E），我们证明TRF 1是TIN 2向端粒的最佳募集所必需的，并记录了与TIN 2-L247 E等位基因相关的表型，这些表型由TIN 2加载到端粒上的不足来解释。为了绕过TRF 1依赖性募集的要求，我们将TIN 2-L247 E融合到Rap 1的TRF 2相互作用（RCT）结构域。RCT-TIN 2-L247 E融合体显示出改善的端粒定位，并且在TRF 2、TPP 1/POT 1a和TPP 1/POT 1b的染色体末端保护方面具有完全功能。这些数据表明，当足够的TIN 2加载到端粒上时，其与TRF 1的相互作用不需要介导TRF 2和TPP 1/POT 1异二聚体的功能。因此，我们得出结论，shelterin可以保护染色体末端作为一个TRF 2栓系的TIN 2/TPP 1/POT 1复合物，缺乏一个物理连接到TRF 1。
The shelterin protein TIN2 is required for the telomeric accumulation of TPP1/POT1 heterodimers and for the protection of telomeres by the POT1 proteins (POT1a and POT1b in the mouse). TIN2 also binds to TRF1 and TRF2, improving the telomeric localization of TRF2 and its function. Here, we ask whether TIN2 needs to interact with both TRF1 and TRF2 to mediate the telomere protection afforded by TRF2 and POT1a/b. Using a TIN2 allele deficient in TRF1 binding (TIN2-L247E), we demonstrate that TRF1 is required for optimal recruitment of TIN2 to telomeres and document phenotypes associated with the TIN2-L247E allele that are explained by insufficient TIN2 loading onto telomeres. To bypass the requirement for TRF1-dependent recruitment, we fused TIN2-L247E to the TRF2-interacting (RCT) domain of Rap1. The RCT-TIN2-L247E fusion showed improved telomeric localization and was fully functional in terms of chromosome end protection by TRF2, TPP1/POT1a, and TPP1/POT1b. These data indicate that when sufficient TIN2 is loaded onto telomeres, its interaction with TRF1 is not required to mediate the function of TRF2 and the TPP1/POT1 heterodimers. We therefore conclude that shelterin can protect chromosome ends as a TRF2-tethered TIN2/TPP1/POT1 complex that lacks a physical connection to TRF1.