End joining at Caenorhabditis elegans Telomeres
End joining at Caenorhabditis elegans Telomeres
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DOI：
10.1534/genetics.108.089920
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发表时间：
2008-10-01
期刊：
影响因子：
3.3
通讯作者：
Ahmed, Shawn
中科院分区：
文献类型：
--
作者：
Lowden, Mia Rochelle;Meier, Bettina;Ahmed, Shawn
严重缩短的端粒可能会受到DNA修复事件，产生端到端的染色体融合。由此产生的双着丝粒染色体可以进入断裂-融合-桥循环，从而阻碍阐明最初融合事件的结构和对其起源的机械理解。当前严重缩短、未加帽端粒融合的分子基础模型依赖于PCR测定，该测定通常捕获染色体末端直接连接产生的融合断点。在这里，我们使用依赖于秀丽隐杆线虫的独特特征的独立方法来研究端粒酶突变体中直接端到端染色体融合的频率：（1）允许稳定的端到端融合的遗传分离的全着丝粒染色体和（2）允许对含有多个端到端融合的基因组DNA样品进行彻底PCR分析的独特亚端粒序列。令人惊讶的是，只有少数端到端融合事件是由直接末端连接而没有额外的基因组重排引起的。我们还证明了C.线虫Ku DNA修复异二聚体不影响端粒长度或在没有端粒酶的情况下引起合成效应。
Critically shortened telomeres can be subjected to DNA repair events that generate end-to-end chromosome fusions. The resulting dicentric chromosomes can enter breakage-fusion-bridge cycles, thereby impeding elucidation of the structures of the initial fusion events and a mechanistic understanding of their genesis. Current models for the molecular basis of fusion of critically shortened, uncapped telomeres rely on PCR assays that typically capture fusion breakpoints created by direct ligation of chromosome ends. Here we use independent approaches that rely on distinctive features of Caenorhabditis elegans to study the frequency of direct end-to-end chromosome fusion in telomerase mutants: ( 1) holocentric chromosomes that allow for genetic isolation of stable end-to-end fusions and (2) unique subtelomeric sequences that allow for thorough PCR analysis of samples of genomic DNA harboring multiple end-to-end fusions. Surprisingly, only a minority of end-to-end fusion events resulted from direct end joining with no additional genome rearrangements. We also demonstrate that deficiency for the C. elegans Ku DNA repair heterodimer does not affect telomere length or cause synthetic effects in the absence of telomerase.