Oxidative DNA Damage And Its Processing

氧化损伤主要通过碱基切除修复(BER)途径从DNA中移除。BER是通过四个酶步骤进行的，但现在很清楚，其他几种蛋白质通过蛋白质-蛋白质相互作用来调节BER效率。我们和其他人确定了核心BER酶的几种蛋白质相互作用。这些蛋白质相互作用是物理和功能的，共同支持“传递接力棒”模型，在该模型中，BER在不同步骤中发生，由单个蛋白质相互作用支持，这些蛋白质相互作用是修复复合体的组成部分，可能位于DNA损伤处。我们正在研究OGG1的其他蛋白质相互作用，以了解氧化损伤的修复在体内是如何调控的。我们发现OGG1也与重组蛋白RAD52相互作用，这表明这两个修复途径之间可能存在相互作用。我们发现这两种蛋白质之间存在功能上的相互作用，其中RAD52刺激OGG1的催化活性，而OGG1抑制RAD52催化的DNA链的退火和侵袭。此外，在暴露于氧化应激的细胞中，OGG1和RAD52之间的物理相互作用增加，表明这种相互作用在细胞对氧化DNA损伤的反应中是重要的。 由于干细胞在发育中至关重要，了解这些细胞如何维持其基因组是非常重要的。因此，我们研究了人类胚胎干细胞的DNA修复特性。有趣的是，这些细胞上调了DNA修复，其中一个显著上调的途径是碱基切除修复途径，用于去除DNA氧化损伤。这证明了这条途径在发展中的核心重要性。

Oxidative lesions are removed from DNA primarily via the base excision repair (BER) pathway. BER is carried out through four enzymatic steps, but it is now clear that several other proteins modulate BER efficiency through protein-protein interactions. We and others identified several protein interactions for the core BER enzymes. These protein interactions are physical and functional and together support the "passing of baton" model, in which BER takes place in different steps supported by individual protein interactions that are components of a repair complex, possibly situated at the DNA lesion. We are studying other protein interactions of OGG1 in order to understand how repair of oxidative lesions is regulated in vivo. We find that OGG1 also interacts with the recombination protein RAD52, suggesting a possible interplay between these two repair pathways. We find a reciprocal functional interaction between these two proteins, in which RAD52 stimulates OGG1 catalytic activity and OGG1 inhibits RAD52-catalysed DNA strand annealing and invasion. Moreover, the physical interaction between OGG1 and RAD52 increases in cells exposed to oxidative stress, indicating that this interaction is important in the cellular response to oxidative DNA damage. Since stem cells are critically important in development, it is very important to understand how these cells maintain their genome. We have therefore examined DNA repair properties in human embryonic stem cells. Interestingly, these cells have upregulated DNA repair and one of the pathways that is markedly upregulated is the base excision repair pathway for removal of oxidative DNA damage. This testifies to the central importance of this pathway in development.