Targeted DNA damage at individual telomeres disrupts their integrity and triggers cell death.
Targeted DNA damage at individual telomeres disrupts their integrity and triggers cell death.
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DOI：
10.1093/nar/gkv598
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发表时间：
2015-07-27
影响因子：
14.9
通讯作者：
Lan L
中科院分区：
文献类型：
--
作者：
Sun L;Tan R;Xu J;LaFace J;Gao Y;Xiao Y;Attar M;Neumann C;Li GM;Su B;Liu Y;Nakajima S;Levine AS;Lan L
细胞DNA被组织成染色体，并被一种独特的核蛋白结构（端粒）覆盖。氧化应激和端粒缩短/功能障碍都会导致衰老相关的退行性病变，并增加癌症风险。然而，端粒DNA（占基因组的<1%）的氧化损伤与端粒功能障碍之间的直接联系尚未建立。通过将KillerRed生色团与端粒重复序列结合因子1（TRF 1）融合，我们开发了一种新的方法来产生对端粒DNA的局部损伤，并在单个端粒水平上监测真实的时间损伤反应。我们发现，与异染色质中相同长度的非端粒区域的DNA损伤相比，U2 OS细胞中长端粒的DNA损伤不能有效修复。端粒DNA损伤缩短了端粒的平均长度，并导致HeLa细胞中的细胞衰老和HeLa、U2 OS和IMR 90细胞中的细胞死亡，此时非端粒区域的DNA损伤不可检测。端粒特异性损伤诱导染色体畸变，包括染色单体端粒丢失和端粒缔合，不同于电离辐射诱导的损伤。综上所述，我们的研究结果表明，氧化损伤诱导端粒功能障碍，并强调维持端粒完整性氧化损伤后的重要性。
Cellular DNA is organized into chromosomes and capped by a unique nucleoprotein structure, the telomere. Both oxidative stress and telomere shortening/dysfunction cause aging-related degenerative pathologies and increase cancer risk. However, a direct connection between oxidative damage to telomeric DNA, comprising <1% of the genome, and telomere dysfunction has not been established. By fusing the KillerRed chromophore with the telomere repeat binding factor 1, TRF1, we developed a novel approach to generate localized damage to telomere DNA and to monitor the real time damage response at the single telomere level. We found that DNA damage at long telomeres in U2OS cells is not repaired efficiently compared to DNA damage in non-telomeric regions of the same length in heterochromatin. Telomeric DNA damage shortens the average length of telomeres and leads to cell senescence in HeLa cells and cell death in HeLa, U2OS and IMR90 cells, when DNA damage at non-telomeric regions is undetectable. Telomere-specific damage induces chromosomal aberrations, including chromatid telomere loss and telomere associations, distinct from the damage induced by ionizing irradiation. Taken together, our results demonstrate that oxidative damage induces telomere dysfunction and underline the importance of maintaining telomere integrity upon oxidative damage.