CEA/DSV/iRCM/SCSR, Laboratoire de Radiopathologie, INSERM-Université Paris VII U967, 92265 Fontenay-aux-Roses, France.
Nucleic Acids Res. 2010 May;38(9):2955-63. doi: 10.1093/nar/gkp1248. Epub 2010 Feb 10.
Telomere maintenance is essential to preserve genomic stability and involves several telomere-specific proteins as well as DNA replication and repair proteins. The kinase ATR, which has a crucial function in maintaining genome integrity from yeast to human, has been shown to be involved in telomere maintenance in several eukaryotic organisms, including yeast, Arabidopsis and Drosophila. However, its role in telomere maintenance in mammals remains poorly explored. Here, we report by using telomere-fluorescence in situ hybridization (Telo-FISH) on metaphase chromosomes that ATR deficiency causes telomere instability both in primary human fibroblasts from Seckel syndrome patients and in HeLa cells. The telomere aberrations resulting from ATR deficiency (i.e. sister telomere fusions and chromatid-type telomere aberrations) are mainly generated during and/or after telomere replication, and involve both leading and lagging strand telomeres as shown by chromosome orientation-FISH (CO-FISH). Moreover, we show that ATR deficiency strongly sensitizes cells to the G-quadruplex ligand 360A, enhancing sister telomere fusions and chromatid-type telomere aberrations involving specifically the lagging strand telomeres. Altogether, these data reveal that ATR plays a critical role in telomere maintenance during and/or after telomere replication in human cells.
端粒维持对于保持基因组稳定性至关重要，涉及几种端粒特异性蛋白以及 DNA 复制和修复蛋白。ATR 激酶在从酵母到人维持基因组完整性方面具有重要作用，已被证明在几种真核生物（包括酵母、拟南芥和果蝇）中参与端粒维持。然而，它在哺乳动物中端粒维持中的作用仍未得到充分探索。在这里，我们通过在中期染色体上进行端粒荧光原位杂交（Telo-FISH）报告，ATR 缺陷导致 Seckel 综合征患者的原代人成纤维细胞和 HeLa 细胞中端粒不稳定。ATR 缺陷导致的端粒异常（即姐妹端粒融合和染色单体型端粒异常）主要在端粒复制期间和/或之后产生，并且如染色体定向-FISH（CO-FISH）所示，涉及前导链和滞后链端粒。此外，我们表明 ATR 缺陷强烈敏化细胞对 G-四链体配体 360A，增强姐妹端粒融合和染色单体型端粒异常，特别是涉及滞后链端粒。总之，这些数据表明 ATR 在人类细胞中端粒复制期间和/或之后的端粒维持中发挥关键作用。
