## 4 Discussion
[PERSON] et al. reported that NRF2 directly binds the antioxidant response elements in the promoter of TIGAR (TP53-induced glycolysis and apoptosis regulator) and upregulates its expression. The enhanced expression of TIGAR accelerates glucose metabolism toward the pentose phosphate pathway [40]. [PERSON] et al. found that NRF2 transcriptionally regulates the expression of 53 BP1, an important mediator of DNA double-strand break repair, supporting the idea that NRF2 is a candidate for tumor therapy [23]. In this study, given that DNJ treatment ameliorated high-glucose-induced 8-OHdG formation, and upregulated NRF2/HO-1 expression, we detected the connection of NRF2 with OGG1, an DNA glycosylase involved in repairing 8-oxoguanine. Our resultsshow that DNJ treatment increases the expression of OGG1. If the transcriptional activity of NRF2 is abrogated by ML385, the enhancement of OGG1 expression is inhibited, and 8-OHdG formation is increased. This indicates that under high glucose, DNJ can protect cells by accelerating the repair of oxidized DNA through activating the NRF2/OGG1 signal. Several other natural products, such as geniposidic acid, resveratrol, and triphlorethol-A were reported to show cell protective roles by upregulating NRF2/OGG1 to alleviate oxidative stress [37, 41, 42]. Oxidative DNA damage leads to the accumulation of DNA mutations, and is an important reason for aging. Our results show that DNJ treatment alleviates cell senescence caused by high glucose, and supports the antioxidant function of DNJ. [PERSON] et al. reported in their recent study that NRF2 positively regulates OGG1 expression in leukemia cells. A chromatin immunoprecipitation assay revealed NRF2 bound to the promoter of OGG1, providing evidence to confirm that OGG1 is a transcriptional target of NRF2 [43]. The expression of NRF2 can be regulated by different protein kinases, such as PKC (protein kinase C) and ERK 1/2 (extracellular signal regulated kinase 1/2) [19]. AKT is another kinase that can regulate the activation of the NRF2 antioxidative response. [PERSON] et al. reported that rehmannioside A improved cognitive impairment after cerebral ischemia by activating PI3K/AKT/NRF2 and inhibiting ferprotosis [44]. [PERSON] et al. reported that flavonoids from a deep-sea-derived _Arthrinium_ sp. protected HUVEC against ox-LDL-induced oxidative stress through activating the AKT/NRF2 pathway [45]. AKT is a master regulator of multiple physiological processes, including glucose metabolism. In cells exposed to DNJ, AKT activation was observed. [PERSON] et al. found that in a mice hyperglycemia model, the intravenous application of DNJ improved insulin sensitivity via activating PI3K/AKT signaling [46]. A similar result was observed in the study conducted by [PERSON] et al. [47]. In the study of [PERSON] et al., they investigated whether DNJ showed effects on the development of atherosclerosis, and found that DNJ inhibited the migration of A7r5 vascular smooth muscle cells (VSMCs) under hypergly conditions, mimicking diabetes. The antimigratory effects of DNJ on VSMC involved the decreased phosphorylation of AKT [48]. [PERSON] et al. reported that DNJ significantly inhibited the adipogenesis of porcine intramuscular adipocytes. Interestingly, DNJ sharply inhibited the phosphorylation of ERK1/2, but did not change the phosphorylation of AKT in intramuscular adipocytes [49]. These previous studies indicate that DNJ affects the activation of AKT in a manner which is dependent on the origin of cells. Our study showed that DNJ stimulates the activation of AKT in HUVEC challenged by high glucose, and leads to the upregulation of NRF2 and OGG1 to protect cells, providing a mechanistic explanation for the antioxidant role of DNJ (Figure 5). [PERSON] et al. performed a study to investigate the combined effects of DNJ with morin on ameliorating insulin resistance and lipid accumulation in prediabetic mice.