Hanna Bishoy M F, Michel Maurice, Helleday Thomas, Mortusewicz Oliver
Science for Life Laboratory, Department of Oncology-Pathology, Karolinska Institutet, 171 65 Stockholm, Sweden.
Weston Park Cancer Centre, Department of Oncology and Metabolism, University of Sheffield, Sheffield S10 2RX, UK.
Int J Mol Sci. 2021 Apr 27;22(9):4542. doi: 10.3390/ijms22094542.
DNA damage caused by reactive oxygen species may result in genetic mutations or cell death. Base excision repair (BER) is the major pathway that repairs DNA oxidative damage in order to maintain genomic integrity. In mammals, eleven DNA glycosylases have been reported to initiate BER, where each recognizes a few related DNA substrate lesions with some degree of overlapping specificity. 7,8-dihydro-8-oxoguanine (8-oxoG), one of the most abundant DNA oxidative lesions, is recognized and excised mainly by 8-oxoguanine DNA glycosylase 1 (OGG1). Further oxidation of 8-oxoG generates hydantoin lesions, which are recognized by NEIL glycosylases. Here, we demonstrate that NEIL1, and to a lesser extent NEIL2, can potentially function as backup BER enzymes for OGG1 upon pharmacological inhibition or depletion of OGG1. NEIL1 recruitment kinetics and chromatin binding after DNA damage induction increase in cells treated with OGG1 inhibitor TH5487 in a dose-dependent manner, whereas NEIL2 accumulation at DNA damage sites is prolonged following OGG1 inhibition. Furthermore, depletion of OGG1 results in increased retention of NEIL1 and NEIL2 at damaged chromatin. Importantly, oxidatively stressed NEIL1- or NEIL2-depleted cells show excessive genomic 8-oxoG lesions accumulation upon OGG1 inhibition, suggesting a prospective compensatory role for NEIL1 and NEIL2. Our study thus exemplifies possible backup mechanisms within the base excision repair pathway.
活性氧引起的DNA损伤可能导致基因突变或细胞死亡。碱基切除修复（BER）是修复DNA氧化损伤以维持基因组完整性的主要途径。在哺乳动物中，已报道有11种DNA糖基化酶启动BER，其中每种酶识别一些具有一定程度重叠特异性的相关DNA底物损伤。7,8-二氢-8-氧代鸟嘌呤（8-氧代G）是最常见的DNA氧化损伤之一，主要由8-氧代鸟嘌呤DNA糖基化酶1（OGG1）识别并切除。8-氧代G的进一步氧化产生乙内酰脲损伤，由NEIL糖基化酶识别。在这里，我们证明，在药理学抑制或OGG1缺失时，NEIL1以及程度较轻的NEIL2可能作为OGG1的备用BER酶发挥作用。在用OGG1抑制剂TH5487处理的细胞中，DNA损伤诱导后NEIL1的募集动力学和染色质结合以剂量依赖性方式增加，而OGG1抑制后NEIL2在DNA损伤位点的积累会延长。此外，OGG1的缺失导致NEIL1和NEIL2在受损染色质上的保留增加。重要的是，在OGG1抑制时，氧化应激的NEIL1或NEIL2缺失细胞显示出过多的基因组8-氧代G损伤积累，这表明NEIL1和NEIL2具有潜在的补偿作用。因此，我们的研究例证了碱基切除修复途径内可能的备用机制。
