Depletion of Deoxyribonucleotide Pools Is an Endogenous Source of DNA Damage in Cells Undergoing Oncogene-Induced Senescence
Depletion of Deoxyribonucleotide Pools Is an Endogenous Source of DNA Damage in Cells Undergoing Oncogene-Induced Senescence
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DOI：
10.1016/j.ajpath.2012.09.011
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发表时间：
2013-01-01
影响因子：
6
通讯作者：
Nikiforov, Mikhail A.
中科院分区：
文献类型：
--
作者：
Mannava, Sudha;Moparthy, Kalyana C.;Nikiforov, Mikhail A.
在正常人类细胞中，癌基因诱导的衰老（OIS）依赖于DNA损伤反应的诱导。氧化应激和基因组DNA的过度复制已被认为是OIS细胞中DNA损伤的主要原因。在这里，我们报告说，下调脱氧核糖核苷池是另一个内源性来源的DNA损伤正常人成纤维细胞（NHF）经历HRAS（G12 V）诱导的衰老。NHF-HRAS（G12 V）细胞低表达胸苷酸合成酶（TS）和核糖核苷酸还原酶（RR），这两种酶是整个从头脱氧核糖核苷酸生物合成所需的，并且具有低dNTP水平。在编码TS和RR的基因的启动子处的染色质富含视网膜母细胞瘤肿瘤抑制蛋白和在赖氨酸9处三甲基化的组蛋白H3。重要的是，异位共表达TS和RR或添加脱氧核糖核苷实质上抑制DNA损伤，衰老相关的表型，并在两种类型的NHF表达HRAS（G12 V）增殖停滞。反过来，短发夹RNA介导的TS和RR抑制导致NHF中的DNA损伤和衰老，尽管效率低于HRAS（G12 V）。然而，TS和RR在静止NHF中的过表达并没有克服增殖停滞，这表明与静止不同，OIS需要耗尽dNTP池和激活DNA复制。我们的数据确定了一个以前未知的作用，脱氧核糖核苷酸的调节OIS。(Am J Pathol 2013，182：142-151; http：//dx·doi·org/10·1016/j·ajpath·2012·09·011）
In normal human cells, oncogene-induced senescence (OIS) depends on induction of DNA damage response. Oxidative stress and hyperreplication of genomic DNA have been proposed as major causes of DNA damage in OIS cells. Here, we report that down-regulation of deoxyribonucleoside pools is another endogenous source of DNA damage in normal human fibroblasts (NHFs) undergoing HRAS(G12V)-induced senescence. NHF-HRAS(G12V) cells underexpressed thymidylate synthase (TS) and ribonucleotide reductase (RR), two enzymes required for the entire de novo deoxyribonucleotide biosynthesis, and possessed low dNTP levels. Chromatin at the promoters of the genes encoding TS and RR was enriched with retinoblastoma tumor suppressor protein and histone H3 tri-methylated at lysine 9. Importantly, ectopic coexpression of TS and RR or addition of deoxyribonucleosides substantially suppressed DNA damage, senescence-associated phenotypes, and proliferation arrest in two types of NHF-expressing HRAS(G12V). Reciprocally, short hairpin RNA-mediated suppression of TS and RR caused DNA damage and senescence in NHFs, although less efficiently than HRAS(G12V). However, overexpression of TS and RR in quiescent NHFs did not overcome proliferation arrest, suggesting that unlike quiescence, OIS requires depletion of dNTP pools and activated DNA replication. Our data identify a previously unknown role of deoxyribonucleotides in regulation of OIS. (Am J Pathol 2013, 182: 142-151; http://dx.doi.org/10.1016/j.ajpath.2012.09.011)