Requirement for functional DNA polymerase eta in genome-wide repair of UV-induced DNA damage during S phase
Requirement for functional DNA polymerase eta in genome-wide repair of UV-induced DNA damage during S phase
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DOI：
10.1016/j.dnarep.2010.03.013
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发表时间：
2010-07-01
期刊：
影响因子：
3.8
通讯作者：
Drobetsky, Elliot A.
中科院分区：
文献类型：
--
作者：
Auclair, Yannick;Rouget, Raphael;Drobetsky, Elliot A.
常染色体隐性遗传疾病着色性干皮病变异体（XPV）的特征在于（i）在细胞水平上表现为紫外线暴露后DNA合成的显著超变和缺陷恢复，以及（ii）临床上表现为异常的日光敏感性和显著的皮肤癌易感性。这些表型明显归因于POLH的种系突变，POLH编码DNA聚合酶eta（pol eta），通常需要准确的translesion DNA合成（TLS）过去UV诱导的环丁烷嘧啶二聚体。在这里，我们证明了暴露于15 J/m2紫外线的患者来源的XPV-skin成纤维细胞也表现出（除了异常TLS之外）仅在S期的全局基因组核苷酸切除修复（GG-NER）的显著缺陷。这种细胞周期特异性GG-NER缺陷可以通过野生型pol eta的异位表达来补充，但不能通过缺乏核再定位或PCNA相互作用的pol eta变体来补充。我们强调了我们实验室以前的一项研究，表明UV暴露，ATR缺陷的Seckel综合征成纤维细胞，如XPV成纤维细胞，在S期人群中表现出GG-NER的强烈衰减。我们现在提出了进一步的证据，表明如果阻止或大大减少UV后阻断的复制叉的形成，则可以在XPV和Seckel综合征细胞中挽救S期修复缺陷，即，分别在UV照射或暴露于相对低的UV剂量（5 J/m（2））之前药理学抑制DNA合成。我们在培养细胞中的发现允许推测，在S期废除GG-NER可能部分有助于（以协同的方式与有缺陷的，易出错的TLS）紫外线超变的极端状态，导致加速皮肤癌的发展在XPV患者。此外，基于整体数据，我们假设，功能性pol eta或-ATR的损失产生异常持久的停滞复制叉在UV-加合位点的DNA，反过来，可以主动和/或被动触发GG-NER抑制。(C)2010 Elsevier B. V.保留所有权利。
The autosomal recessive disorder Xeroderma pigmentosum-variant (XPV) is characterized (i) at the cellular level by dramatic hypermutability and defective recovery of DNA synthesis following UV exposure, and (ii) clinically by abnormal sunlight sensitivity and remarkable predisposition to skin cancer. These phenotypes are clearly attributable to germline mutations in POLH, encoding DNA polymerase eta (pol eta) normally required for accurate translesion DNA synthesis (TLS) past UV-induced cyclobutane pyrimidine dimers. Here we demonstrate that patient-derived XPV-skin fibroblasts exposed to 15J/m(2) of UV also exhibit (in addition to abnormal TLS) a significant defect in global-genomic nucleotide excision repair (GG-NER) exclusively during S phase. This cell cycle-specific GG-NER defect can be complemented by ectopic expression of wild-type pol eta, but not of pol eta variants deficient in either nuclear relocalization or PCNA interaction. We highlight a previous study from our laboratory demonstrating that UV-exposed, ATR-deficient Seckel syndrome fibroblasts, like XPV fibroblasts, manifest strong attenuation of GG-NER uniquely in S phase populations. We now present further evidence suggesting that deficient S phase repair can be rescued in both XPV- and Seckel syndrome-cells if the formation of blocked replication forks post-UV is either prevented or substantially reduced, i.e., following, respectively, pharmacological inhibition of DNA synthesis prior to UV irradiation, or exposure to a relatively low UV dose (5J/m(2)). Our findings in cultured cells permit speculation that abrogation of GG-NER during S phase might partially contribute (in a synergistic manner with defective, atypically error-prone TLS) to the extreme state of UV-hypermutability leading to accelerated skin cancer development in XPV patients. Moreover, based on the overall data, we postulate that loss of either functional pol eta or -ATR engenders abnormal persistence of stalled replication forks at UV-adducted sites in DNA which, in turn, can actively and/or passively trigger GG-NER inhibition. (C) 2010 Elsevier B.V. All rights reserved.