Neil2-null Mice Accumulate Oxidized DNA Bases in the Transcriptionally Active Sequences of the Genome and Are Susceptible to Innate Inflammation
Neil2-null Mice Accumulate Oxidized DNA Bases in the Transcriptionally Active Sequences of the Genome and Are Susceptible to Innate Inflammation
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DOI：
10.1074/jbc.m115.658146
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发表时间：
2015-10-09
影响因子：
4.8
通讯作者：
Hazra, Tapas K.
中科院分区：
文献类型：
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作者：
Chakraborty, Anirban;Wakamiya, Maki;Hazra, Tapas K.
为什么哺乳动物细胞具有多种具有重叠底物范围的DNA糖基酶(DGs)，用于通过碱基切除修复(BER)途径修复氧化损伤的碱基，这是一个长期存在的问题。为了确定这些DG的生物学作用，已经建立了零动物模型。在这里，我们报告了缺乏Neil2(Nei-like 2)的小鼠的产生和特征。与其他四种氧化碱基特异性DG(OGG1、NTH1、NEIL1和NEIL3)中每一种都缺乏的小鼠一样，Neil2缺失的小鼠没有明显的表型。然而，中年到老年的Neil2基因缺失小鼠表现出氧化基因组损伤的积累，主要是在转录区域。野生型(WT)小鼠组织的免疫下拉分析表明，NEIL2与RNA聚合酶II，以及Cockayne综合征B组蛋白、TFIIH和其他BER蛋白有关。小鼠组织染色质免疫沉淀分析表明，NEIL2和RNA聚合酶II仅在转录基因上共存，这与我们早期关于NEIL2的S在转录偶联BER中的作用的体外研究结果一致。这项研究首次提供了哺乳动物基因组区域特异性修复的体内证据。此外，在Neil2基因缺失小鼠的胚胎成纤维细胞中观察到端粒丢失和基因组不稳定的频率比来自WT的小鼠更高。此外，Neil2基因缺失的小鼠比WT小鼠对炎症介质的反应更快。综上所述，我们的结果强调了NEIL2在保护哺乳动物免受与基因组不稳定和/或炎症有关的各种病理发展中的重要性。因此，NEIL2很可能在长期的基因组维持中发挥重要作用，特别是在人类等长寿哺乳动物中。
Why mammalian cells possess multiple DNA glycosylases (DGs) with overlapping substrate ranges for repairing oxidatively damaged bases via the base excision repair (BER) pathway is a long-standing question. To determine the biological role of these DGs, null animal models have been generated. Here, we report the generation and characterization of mice lacking Neil2 (Nei-like 2). As in mice deficient in each of the other four oxidized base-specific DGs (OGG1, NTH1, NEIL1, and NEIL3), Neil2-null mice show no overt phenotype. However, middle-aged to old Neil2-null mice show the accumulation of oxidative genomic damage, mostly in the transcribed regions. Immunopulldown analysis from wild-type (WT) mouse tissue showed the association of NEIL2 with RNA polymerase II, along with Cockayne syndrome group B protein, TFIIH, and other BER proteins. Chromatin immunoprecipitation analysis from mouse tissue showed co-occupancy of NEIL2 and RNA polymerase II only on the transcribed genes, consistent with our earlier in vitro findings on NEIL2's role in transcription-coupled BER. This study provides the first in vivo evidence of genomic region-specific repair in mammals. Furthermore, telomere loss and genomic instability were observed at a higher frequency in embryonic fibroblasts from Neil2-null mice than from the WT. Moreover, Neil2-null mice are much more responsive to inflammatory agents than WT mice. Taken together, our results underscore the importance of NEIL2 in protecting mammals from the development of various pathologies that are linked to genomic instability and/or inflammation. NEIL2 is thus likely to play an important role in long term genomic maintenance, particularly in long- lived mammals such as humans.