TERRA promotes telomere shortening through exonuclease 1-mediated resection of chromosome ends.
TERRA promotes telomere shortening through exonuclease 1-mediated resection of chromosome ends.
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DOI：
10.1371/journal.pgen.1002747
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发表时间：
2012
期刊：
影响因子：
4.5
通讯作者：
Lingner J
中科院分区：
文献类型：
--
作者：
Pfeiffer V;Lingner J
含有RNA的长的非编码端粒重复序列(Terra)在染色体末端表达。在实验性操作或ICF(免疫缺陷、着丝粒不稳定、面部畸形)患者中，Terra上调与短端粒有关。为了研究Terra在酿酒酵母中控制端粒长度的机制，我们在端粒1L处定位了Terra的转录起始点，并在上游插入了多西环素可调节启动子。Terra转录的诱导导致1L的端粒缩短，但其他染色体末端不缩短。Terra与抑制Exo1的Ku70/80复合体相互作用，在端粒酶存在和不存在的情况下，ExO1的缺失而不是Mre11的缺失完全抑制了Terra介导的短端粒表型。因此，Terra转录促进了染色体末端Exo1的5‘-3’核酸酶活性，为调节端粒缩短速率提供了一种手段。因此，端粒转录可以通过调节染色体末端加工活动来调节细胞寿命。端粒保护染色体末端不受末端融合和末端降解的影响，并调节细胞寿命。端粒酶是一种逆转录酶，维持端粒长度。末端复制问题和核酸酶对DNA末端的处理导致端粒缩短。端粒被转录成一种名为Terra的长长的非编码RNA。ICF综合征患者细胞端粒较短，TERRA较丰富。Terra在体外抑制端粒酶活性。为了分析Terra在体内的功能，我们使用了模式生物酿酒酵母。我们鉴定了染色体一端的天然Terra启动子，并用人工启动子取代了它，以用药物调节Terra转录。Terra诱导导致这一特定染色体末端的端粒缩短。我们发现，端粒缩短是端粒转录后5‘-3’外切酶1激活增加的结果，但对端粒酶招募和活性没有显著影响。Ku蛋白控制着染色体末端的核酸外切酶1的活性。Terra与Ku在物理和遗传上相互作用，似乎干扰了它抑制外切酶1的能力。因此，我们证明了Terra的表达是如何通过调节染色体末端的处理来控制端粒长度的。因此，端粒转录可以独立于端粒酶调节细胞寿命。
The long noncoding telomeric repeat containing RNA (TERRA) is expressed at chromosome ends. TERRA upregulation upon experimental manipulation or in ICF (immunodeficiency, centromeric instability, facial anomalies) patients correlates with short telomeres. To study the mechanism of telomere length control by TERRA in Saccharomyces cerevisiae, we mapped the transcriptional start site of TERRA at telomere 1L and inserted a doxycycline regulatable promoter upstream. Induction of TERRA transcription led to telomere shortening of 1L but not of other chromosome ends. TERRA interacts with the Exo1-inhibiting Ku70/80 complex, and deletion of EXO1 but not MRE11 fully suppressed the TERRA–mediated short telomere phenotype in presence and absence of telomerase. Thus TERRA transcription facilitates the 5′-3′ nuclease activity of Exo1 at chromosome ends, providing a means to regulate the telomere shortening rate. Thereby, telomere transcription can regulate cellular lifespan through modulation of chromosome end processing activities. Telomeres protect chromosome ends from end fusion and end degradation, and they regulate cellular lifespan. Telomerase, a reverse transcriptase, maintains telomere length. The end replication problem and the processing of DNA ends by nucleases cause telomere shortening. Telomeres are transcribed into a long noncoding RNA known as TERRA. ICF syndrome derived patient cells have short telomeres and enriched TERRA. TERRA inhibits telomerase activity in vitro. To analyze TERRA function in vivo, we used the model organism Saccharomyces cerevisiae. We identified the natural TERRA promoter at one chromosome end and replaced it with an artificial promoter to modulate TERRA transcription with a drug. TERRA induction leads to telomere shortening at this specific chromosome end. We show that telomere shortening is a consequence of increased activation of the 5′-3′ Exonuclease 1 at the transcribed telomere with no notable effects on telomerase recruitment and activity. The Ku protein controls Exonuclease 1 activity at chromosome ends. TERRA physically and genetically interacts with Ku and appears to interfere with its ability to inhibit Exonuclease 1. Thus, we demonstrate how TERRA expression controls telomere length through the regulation of the processing of chromosome ends. Therefore, telomere transcription can regulate cellular lifespan independently of telomerase.
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DOI：
10.1126/science.1170633
发表时间：
2009-11-13
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
de Lange T
通讯作者：
de Lange T
影响因子：
11.4
作者：
Marcand, S;Brevet, V;Gilson, E
通讯作者：
Gilson, E
影响因子：
56.9
作者：
Azzalin, Claus M.;Reichenbach, Patrick;Lingner, Joachim
通讯作者：
Lingner, Joachim
影响因子：
3.2
作者：
ITO, H;FUKUDA, Y;KIMURA, A
通讯作者：
KIMURA, A
影响因子：
16.8
作者：
Fisher, TS;Taggart, AKP;Zakian, VA
通讯作者：
Zakian, VA