Direct and indirect roles of RECQL4 in modulating base excision repair capacity
Direct and indirect roles of RECQL4 in modulating base excision repair capacity
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DOI：
10.1093/hmg/ddp291
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发表时间：
2009-09-15
影响因子：
3.5
通讯作者：
Bohr, Vilhelm A.
中科院分区：
文献类型：
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作者：
Schurman, Shepherd H.;Hedayati, Mohammad;Bohr, Vilhelm A.
RECQL4是一种人类RecQ解旋酶，在大约三分之二的Rothmund-Thomson综合征(RTS)患者中发生突变，RTS是一种以染色体不稳定为特征的细胞水平的疾病。BLM和WRN也是人类RecQ解旋酶，分别在Bloom和Werner综合征中突变，与染色体不稳定和过早衰老有关。在这里，我们发现原代RTS和RECQL4 siRNA敲除的人成纤维细胞积累了更多的H_2O_2诱导的DNA链断裂，表明RECQL4可能刺激H_2O_2诱导的DNA损伤的修复。RTS原代成纤维细胞在内源性或诱导性氧化应激反应中也比对照细胞积累更多的XRCC1焦点，并具有较高的内源性甲酰胺嘧啶基础水平。在过氧化氢处理的细胞中，RECQL4与APE1和FEN1共定位，APE1和FEN1是碱基切除修复的关键参与者。生化实验表明，RECQL4能特异性地刺激APE1的脱嘌呤核酸内切酶活性、DNA聚合酶β的DNA链置换活性，以及被FET酶I切割的1或10个核苷酸的DNA底物。此外，RTS细胞表现出BER途径基因的上调，不能像正常细胞那样对氧化应激做出反应。这里的数据支持RECQL4直接和间接调节碱基切除修复能力的模型。
RECQL4 is a human RecQ helicase which is mutated in approximately two-thirds of individuals with Rothmund-Thomson syndrome (RTS), a disease characterized at the cellular level by chromosomal instability. BLM and WRN are also human RecQ helicases, which are mutated in Bloom and Werner's syndrome, respectively, and associated with chromosomal instability as well as premature aging. Here we show that primary RTS and RECQL4 siRNA knockdown human fibroblasts accumulate more H2O2-induced DNA strand breaks than control cells, suggesting that RECQL4 may stimulate repair of H2O2-induced DNA damage. RTS primary fibroblasts also accumulate more XRCC1 foci than control cells in response to endogenous or induced oxidative stress and have a high basal level of endogenous formamidopyrimidines. In cells treated with H2O2, RECQL4 co-localizes with APE1, and FEN1, key participants in base excision repair. Biochemical experiments indicate that RECQL4 specifically stimulates the apurinic endonuclease activity of APE1, the DNA strand displacement activity of DNA polymerase beta, and incision of a 1- or 10-nucleotide flap DNA substrate by Flap Endonuclease I. Additionally, RTS cells display an upregulation of BER pathway genes and fail to respond like normal cells to oxidative stress. The data herein support a model in which RECQL4 regulates both directly and indirectly base excision repair capacity.