Enzymatically inactive OGG1 binds to DNA and steers base excision repair toward gene transcription
Enzymatically inactive OGG1 binds to DNA and steers base excision repair toward gene transcription
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酶失活的 OGG1 与 DNA 结合并引导碱基切除修复朝向基因转录
DOI：
10.1096/fj.201902243r
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发表时间：
2020-05-06
期刊：
影响因子：
4.8
通讯作者：
Ba, Xueqing
中科院分区：
文献类型：
--
作者：
Hao, Wenjing;Wang, Jing;Ba, Xueqing
8-氧鸟嘌呤DNA糖基化酶1 （OGG1）启动碱基切除修复（BER）是从DNA中去除诱变前的8-氧-7,8-二氢鸟嘌呤（8-oxoG）的主要途径。最近的研究表明，8-oxoG作为一种表观遗传样标记，OGG1调节氧化应激细胞的基因表达。对于OGG1的这种新作用，已经提出了两种不同的机制：一种是与碱基切除相耦合的，而另一种只需要OGG1的底物结合——两者都导致相邻DNA序列的构象调整，为转录因子提供了进入其顺式元件的途径。本研究旨在研究促炎基因表达是否需要BER活性的OGG1。为此，用表达Ogg1野生型（wt）和Ogg1修复缺陷突变体的构建体转染Ogg1/ Ogg1敲除/缺失细胞。检测OGG1启动子的富集、氧化状态和基因表达。结果显示，TNF α暴露增加了wt OGG1的氧化修饰半胱氨酸(s)水平，但不损害其与启动子和促进基因表达的关联。切除缺陷的K249Q突变体甚至是更有效的基因表达激活因子；而底物识别/结合受损的突变体OGG1则没有。这些数据表明，OGG1与其底物在调控区域的相互作用以及相邻DNA的构象调整是调节炎症基因表达的主要模式。
8-Oxoguanine DNA glycosylase1 (OGG1)-initiated base excision repair (BER) is the primary pathway to remove the pre-mutagenic 8-oxo-7,8-dihydroguanine (8-oxoG) from DNA. Recent studies documented 8-oxoG serves as an epigenetic-like mark and OGG1 modulates gene expression in oxidatively stressed cells. For this new role of OGG1, two distinct mechanisms have been proposed: one is coupled to base excision, while the other only requires substrate binding of OGG1--both resulting in conformational adjustment in the adjacent DNA sequences providing access for transcription factors to their cis-elements. The present study aimed to examine if BER activity of OGG1 is required for pro-inflammatory gene expression. To this end, Ogg1/OGG1 knockout/depleted cells were transfected with constructs expressing wild-type (wt) and repair-deficient mutants of OGG1. OGG1's promoter enrichment, oxidative state, and gene expression were examined. Results showed that TNF alpha exposure increased levels of oxidatively modified cysteine(s) of wt OGG1 without impairing its association with promoter and facilitated gene expression. The excision deficient K249Q mutant was even a more potent activator of gene expression; whereas, mutant OGG1 with impaired substrate recognition/binding was not. These data suggested the interaction of OGG1 with its substrate at regulatory regions followed by conformational adjustment in the adjacent DNA is the primary mode to modulate inflammatory gene expression.