Mutations in the telomere-binding protein POT1 are associated with solid tumors and leukemias. POT1 alterations cause rapid telomere elongation, ATR kinase activation, telomere fragility, and accelerated tumor development. Here, we define the impact of mutant POT1 alleles through complementary genetic and proteomic approaches based on CRISPR interference and biotin-based proximity labeling, respectively. These screens reveal that replication stress is a major vulnerability in cells expressing mutant POT1, which manifests as increased telomere mitotic DNA synthesis at telomeres. Our study also unveils a role for the nuclear pore complex in resolving replication defects at telomeres. Depletion of nuclear pore complex subunits in the context of POT1 dysfunction increases DNA damage signaling, telomere fragility and sister chromatid exchanges. Furthermore, we observed telomere repositioning to the nuclear periphery driven by nuclear F-actin polymerization in cells with POT1 mutations. In conclusion, our study establishes that relocalization of dysfunctional telomeres to the nuclear periphery is critical to preserve telomere repeat integrity.

中文翻译：

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POT1功能障碍赋予的复制压力促进端粒重新定位到核孔

端粒结合蛋白POT1中的突变与实体瘤和白血病有关。POT1改变导致端粒快速伸长，ATR激酶激活，端粒脆性和加速肿瘤发展。在这里，我们定义了突变体POT1的影响等位基因分别通过基于CRISPR干扰和基于生物素的邻近标记的互补遗传和蛋白质组学方法进行。这些筛选显示复制压力是表达突变体POT1的细胞中的主要脆弱性，表现为端粒端粒有丝分裂DNA合成的增加。我们的研究还揭示了核孔复合体在解决端粒复制缺陷中的作用。在POT1功能障碍的情况下，核孔复合物亚单位的耗竭会增加DNA损伤信号传导，端粒易碎性和姐妹染色单体交换。此外，我们观察到端粒重新定位在POT1细胞中由核F-肌动蛋白聚合驱动的核外围突变。总之，我们的研究建立了功能失调的端粒重新定位到核外围对于保持端粒重复序列完整性至关重要。