Continuous elimination of oxidized nucleotides is necessary to prevent rapid onset of cellular senescence
Continuous elimination of oxidized nucleotides is necessary to prevent rapid onset of cellular senescence
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DOI：
10.1073/pnas.0809834106
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发表时间：
2009-01-06
影响因子：
11.1
通讯作者：
Weinberg, Robert A.
中科院分区：
文献类型：
--
作者：
Rai, Priyamvada;Onder, Tamer T.;Weinberg, Robert A.
活性氧（ROS）似乎在限制细胞和器官寿命方面发挥作用。然而，由于它们的多效性作用，很难将启动细胞衰老过程中的特定作用归因于ROS。我们研究了氧化性DNA损伤对细胞增殖的影响，认为这种损伤对引发衰老至关重要。为此，我们设计了一种策略，将8-氧代鸟嘌呤（一种主要的氧化DNA损伤）水平与ROS水平脱钩。MTH 1表达的抑制，水解8-氧代-dGTP，伴随着增加的总细胞8-氧代鸟嘌呤水平，并导致早期传代的原代和端粒酶永生化的人皮肤成纤维细胞迅速经历衰老，这样做而不改变细胞ROS水平。这种衰老表型概括了复制性衰老的几个显著特征，特别是衰老相关β-半乳糖苷酶（SA β-gal）活性的存在，明显不可修复的基因组DNA断裂，以及p21（Cip 1），p53和p16（INK 4A）肿瘤抑制蛋白水平的升高。在低氧张力（3%）下培养细胞在很大程度上防止了shMTH 1依赖性衰老表型。这些结果表明，核苷酸池是细胞内ROS的一个关键目标，氧化的核苷酸，除非不断消除，可以迅速诱导细胞衰老，通过信号转导途径非常相似的复制衰老过程中激活。
Reactive oxygen species (ROS) appear to play a role in limiting both cellular and organismic lifespan. However, because of their pleiotropic effects, it has been difficult to ascribe a specific role to ROS in initiating the process of cellular senescence. We have studied the effects of oxidative DNA damage on cell proliferation, believing that such damage is of central importance to triggering senescence. To do so, we devised a strategy to decouple levels of 8-oxoguanine, a major oxidative DNA lesion, from ROS levels. Suppression of MTH1 expression, which hydrolyzes 8-oxo-dGTP, was accompanied by increased total cellular 8-oxoguanine levels and caused early-passage primary and telomerase-immortalized human skin fibroblasts to rapidly undergo senescence, doing so without altering cellular ROS levels. This senescent phenotype recapitulated several salient features of replicative senescence, notably the presence of senescence-associated beta-galactosidase ( SA beta-gal) activity, apparently irreparable genomic DNA breaks, and elevation of p21(Cip1), p53, and p16(INK4A) tumor suppressor protein levels. Culturing cells under low oxygen tension (3%) largely prevented the shMTH1-dependent senescent phenotype. These results indicate that the nucleotide pool is a critical target of intracellular ROS and that oxidized nucleotides, unless continuously eliminated, can rapidly induce cell senescence through signaling pathways very similar to those activated during replicative senescence.