Search Results (110)

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by demyelination and neurodegeneration. While its etiology remains unclear, both genetic and environmental factors, including oxidative stress, have been implicated in the development of the disease. The base excision repair (BER) pathway plays a critical role in repairing oxidative DNA damage. This study investigated the association between polymorphisms in BER-related genes and MS susceptibility in a Central European population. Ten SNPs across seven BER genes were genotyped in 102 patients with MS and 118 healthy controls. Six SNPs were significantly associated with MS. Increased risk was observed for rs25478 in XRCC1 (OR = 2.37, 95% CI: 1.44–3.91, p < 0.0001), rs3087404 in SMUG1 (OR = 2.80, 95% CI: 1.49–5.26, p = 0.0012), and rs3219493 in MUTYH (OR = 2.23, 95% CI: 1.35–3.67, p = 0.0018). Conversely, reduced risk was associated with rs2307293 in MBD4 (OR = 0.42, 95% CI: 0.23–0.78, p = 0.006), rs3219489 in MUTYH (OR = 0.55, 95% CI: 0.31–0.97, p = 0.038), and rs4135054 in TDG (OR = 0.52, 95% CI: 0.29–0.94, p = 0.031). Haplotype analysis was performed for SNPs in strong linkage disequilibrium. Only rs3219489 and rs3219472 within the MUTYH gene showed strong LD (r² = 0.90), justifying haplotype-based analysis. Among four inferred haplotypes, the rare G–C haplotype was significantly associated with reduced MS risk (Score = −2.10, p = 0.035), suggesting a protective effect of this allele combination. Other SNPs not in LD were analyzed using a multivariable logistic regression model. Significant associations with decreased MS risk were found for rs1052133 in OGG1 (OR = 0.57, p = 0.043), rs2307293 in MBD4 (OR = 0.16, p = 0.010), and rs4135054 in TDG (OR = 0.38, p < 0.001), while rs3087404 in SMUG1 increased MS risk (OR = 1.98, p = 0.013). These results suggest that genetic variation in BER genes, including both single SNP effects and haplotypes, contributes to MS susceptibility. Further studies are warranted to explore the functional consequences of these variants and validate findings in larger, independent cohorts. Full article

Methionine restriction (MetR) is a dietary intervention that extends mean and maximum life span in rodents, at least in part, by reducing oxidative stress and promoting DNA stability in different tissues. Regarding DNA stability, DNA repair pathways play a critical role, both in the nuclear and mitochondrial fractions. Base excision repair (BER) is the main one involved in the repair of oxidative damage, as well as the main one in mitochondria. Despite the relevance of DNA repair in DNA maintenance, it is not known whether MetR regulates BER as a mechanism of preserving genomic stability. In this study we analyzed, for the first time, the effect of 40% MetR for 7 weeks on BER in rat brain cortex and liver, focusing on the expression of several key BER genes. In the brain cortex, MetR significantly increased the gene expression of the DNA glycosylase Ogg1 and the DNA endonuclease Ape1 while reducing DNA polymerase γ gene expression. Conversely, MetR led to a general reduction in the expression of BER genes in the liver. Our findings highlight a tissue-specific regulation of the BER gene expression in response to MetR. Different potential mechanisms underlying these changes in BER, such as DNA methylation or activation of signaling pathways, are discussed. Full article

The Chinese tongue sole (Cynoglossus semilaevis) is a commercially important mariculture species; however, its fertilization and hatching rates under artificial conditions remain relatively low. Zona pellucida proteins (ZPs), which mediate sperm–egg binding, were previously identified as differentially expressed genes between newly differentiated ovaries and testes in C. semilaevis. In this study, we identified 25 ZPs of C. semilaevis through genomic analysis and classified them into five subfamilies. All genes possessed a conserved ZP domain, characteristic of the gene family from mammals to teleosts. Among them, nine genes were highly expressed in ovary cells, with the expression levels increasing during ovarian development, while another three genes were predominantly expressed in liver cells. Protein–protein interaction analysis predicted that 12 ZPs interacted with key reproductive regulators such as Gdf9, Arid4a, Arid4b, and Rbl, which were involved in steroidogenesis, sperm–egg recognition, and folliculogenesis. Functional analyses using RNA interference revealed that Cszpc7-1 knockdown in ovarian cells led to the downregulation of cyp19a, esr2, bmp15, and adamts-1, while the expression of rbl, gnas, adgrl1, and adgrl2 was upregulated. In contrast, Cszpax1 knockdown resulted in decreased expression of cyp19a, foxl2, arid4a, and zeb1, along with upregulation of arid4b, ogg1, and gdf9. These results suggested that ZP genes might contribute to ovarian homeostasis by regulating steroid hormone synthesis, follicular development, and ovulation. This study contributed to a deeper understanding of the reproductive mechanisms of C. semilaevis and provided evolutionary insights into the functional divergence of the ZP gene family across teleosts. Full article

Endothelial calcium dysregulation underlies impairments in endothelial-dependent vasodilation (EDV), contributing to vascular disease progression. Repletion of 8-oxoguanine DNA glycosylase (OGG1), an enzyme involved in base excision repair, has been shown to forestall vascular disease progression. However, the role of OGG1 in regulating endothelial calcium dynamics and in preserving EDV is unknown. Here, calcium imaging via high-speed confocal microscopy and automated analytics was used to quantify the spatial and temporal parameters of endothelial calcium signals in the excised carotid arteries of male and female C57BL6J/FVBNJ mice aged 4–7 months with normal endogenous levels of OGG1, in mice lacking OGG1, and in mice with repleted human OGG1 targeted to the mitochondria. Mice lacking OGG1 exhibited an anomalous calcium phenotype characterized by a substantial increase in the basal tissue-wide frequency and spatial area of the endothelial calcium signals. Mitochondrial repletion of hOGG1 restored the calcium phenotype under unstimulated and acetylcholine-stimulated conditions. EDV was assessed using pressure myography. Mice lacking OGG1 exhibited significant impairments in EDV in response to acetylcholine, and the mitochondrial repletion of OGG1 rescued EDV. These findings highlight a novel role for OGG1 in endothelial signaling and suggest its importance in vascular homeostasis. Full article

Oxidative stress, resulting from an imbalance between reactive oxygen species (ROS) production and antioxidant defenses, plays a crucial role in tumor development. Tumor cells often experience elevated oxidative stress due to rapid proliferation and unstable metabolism, leading to DNA damage. The enzyme 8-oxoguanine DNA glycosidase (OGG1) is central to repairing oxidative DNA damage, thereby maintaining genomic stability. In addition to its DNA repair function, OGG1 also plays a role in gene expression under oxidative stress. This study examined the expression pattern of cadherin-3 (CDH3), a cell adhesion protein associated with cancer metastasis and poor prognosis, under oxidative stress. Our findings showed that oxidative stress upregulated CDH3 expression, with OGG1 playing a pivotal role. Analysis of the CDH3 promoter revealed SP1 binding sites, and ChIP-qPCR assays confirmed OGG1’s involvement in modulating SP1 binding. These results provided new insights into the regulation of CDH3 under oxidative stress and suggested potential therapeutic strategies targeting CDH3 in cancer treatment. Full article

Aging and age-related neurodegenerative disorders are characterized by the dysfunction or loss of brain nicotinic acetylcholine receptors (nAChRs), and these changes may be related to other senescence markers, such as oxidative stress and DNA repair dysfunction. However, the mechanism of nAChR loss in the aging brain and the modification of this process by drugs (e.g., memantine, Mem) are not yet fully understood. To study whether the differences in nAChR expression in the rat brain occur due to aging or oxidative stress and are modulated by Mem, we analyzed nAChR subunits (at RNA and protein levels) and other biomarkers by real-time quantitative polymerase chain reaction (RQ-PCR) and Western blot validation. Twenty-one female Wistar rats were divided into four groups, depending on age, and the oldest group received injections of Mem or water with the use of intragastric catheters. We studied the cerebral grey matter (CGM), subcortical white matter (SCWM), and cerebellum (Ce). Results showed an age-related decrease of α7 nAChR mRNA level in SCWM. The α7 nAChR mRNA loss was accompanied by reduced expression of 8-oxoguanine DNA glycosylase 1 (OGG1) and an increased tumor necrosis factor alpha (TNFα) level. In the water group, we observed a higher level of α7 nAChR protein in the SCWM and Ce. Biomarker levels changed, but to a different extent depending on the brain area. Importantly, the dysfunction in antioxidative status was stopped and even regressed under Mem treatment. After two weeks of treatment, an increase in TP53 protein level and a decrease in 8-oxo-2′deoxyguanosine (8-oxo-2′dG) level were observed. We conclude that Mem administration may be protective against the senescence process by antioxidative mechanisms. Full article

Genomic integrity is critical for cellular homeostasis, preventing the accumulation of mutations that can drive diseases such as cancer. Among the mechanisms safeguarding genomic stability, the Base Excision Repair (BER) pathway plays a pivotal role in counteracting oxidative DNA damage caused by reactive oxygen species. Central to this pathway are enzymes like 8-oxoguanine glycosylase 1 (OGG1), which recognize and excise 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) lesions, thereby initiating a series of repair processes that restore DNA integrity. BER inhibitors have recently been identified as a promising approach in cancer therapy, increasing the sensitivity of cancer cells to radiotherapy and chemotherapy. By exploiting tumor-specific DNA repair dependencies and synthetic lethal interactions, these inhibitors could be used to selectively target cancer cells while sparing normal cells. This review provides a robust reference for scientific researchers, offering an updated perspective on small-molecule inhibitors targeting the 8-oxodG-BER pathway and highlighting their potential role in expanding cancer treatment strategies. Full article

8-oxoguanine DNA glycosylase-1 (OGG1) is a DNA glycosylase mediating the first step in base excision repair which removes 7,8-dihydro-8-oxoguanine (8-oxoG) and repairs oxidized nuclear and mitochondrial DNA. Previous studies showed that OGG1 deficiency results in an increased susceptibility to high-fat diet (HFD)-induced obesity and metabolic dysfunction in mice, suggesting a crucial role of OGG1 in metabolism. However, the tissue-specific mechanisms of how OGG1 deficiency leads to insulin resistance is unknown. Thus, in the current study, we used a hyperinsulinemic-euglycemic clamp to evaluate in-depth glucose metabolism in male wild-type (WT) mice and Ogg1−/− (Ogg1-KO) mice fed an HFD. Ogg1-KO mice fed HFD were more obese, with significantly lower hepatic insulin action compared to WT/HFD mice. Targeting human OGG1 to mitochondria protected against HFD-induced obesity, insulin resistance, oxidative mitochondrial DNA damage in the liver and showed decreased expression of liver gluconeogenic genes in Ogg1-KO mice, suggesting a putative protective mechanism. Additionally, several subunits of oxidative phosphorylation protein levels were noticeably increased in Ogg1-KO/Tg compared to Ogg1-KO mice fed an HFD which was associated with improved insulin signaling. Our findings demonstrate the crucial role of mitochondrial hOGG1 in HFD-induced insulin resistance and propose several protective mechanisms which can further direct the development of therapeutic treatment. Full article

Background/Objectives: 8-hydroxy-2′-deoxyguanosine (8-OHdG) is a form of oxidative DNA damage caused by oxidative stress (OS), which is considered a major factor in male infertility. The cellular defense system against 8-OHdG involves base excision repair (BER) with the enzyme 8-Oxoguanine DNA glycosylase 1 (OGG1). However, studies on the single-nucleotide polymorphism (SNP) OGG1 Ser326Cys have demonstrated that the Cys326Cys genotype could be the cause of an increment in oxidative DNA damage. In this study, the OGG1 Ser326Cys polymorphism and its effect on DNA oxidation were evaluated in 118 infertile men. Methods: Polymorphic screening was performed using TaqMan allelic discrimination assays, and oxidative DNA damage was evaluated through the quantification of 8-OHdG and total antioxidant capacity (TAC); in addition, electrical bioimpedance spectroscopy (EBiS) measurements were used as a reference for different electrical properties associated with 8-OHdG concentrations. Results: The detected Cys (G) allele frequency (0.4) was higher compared to the allele frequency reported in the “Allele Frequency Aggregator” (ALFA) and “Haplotype Map” (HapMap) projects for American populations (0.21–0.29), suggesting that the Cys (G) allele carrier could be a factor associated with American infertile populations. The values of 8-OHdG were twofold higher in carriers of the Cys326Cys (GG) genotype than the other genotypes and, in concordance, the TAC levels were threefold lower in Cys326Cys (GG) genotype carriers compared to the other genotypes. Moreover, the EBiS magnitude exhibited potential for the detection of different oxidative damage in DNA samples between genotypes. Conclusions: The Cys326Cys (GG) genotype is associated with oxidative DNA damage that could contribute to male infertility. Full article

The consequences of stroke include cognitive deficits and sensorimotor disturbances, which are largely related to mitochondrial impairments in the brain. In this work, we have shown that the mimetic of the ketogenic diet beta-hydroxybutyrate (βHB) can improve neurological brain function in stroke. At 3 weeks after photothrombotic stroke, mice receiving βHB with drinking water before and after surgery recovered faster in terms of sensorimotor functions assessed by the string test and static rods and cognitive functions assessed by the Morris water maze. At the same time, the βHB-treated mice had lower expression of some markers of astrocyte activation and inflammation (Gfap, Il-1b, Tnf). We hypothesize that long-term administration of βHB promotes the activation of the nuclear factor erythroid 2-related factor 2/antioxidant response element (Nrf2/ARE) pathway, which leads to increased expression of antioxidant genes targeting mitochondria and genes involved in signaling pathways necessary for the maintenance of synaptic plasticity. βHB partially maintained mitochondrial DNA (mtDNA) integrity during the first days after photothrombosis. However, in the following three weeks, the number of mtDNA damages increased in all experimental groups, which coincided with a decrease in Ogg1 expression, which plays an important role in mtDNA repair. Thus, we can assume that βHB is not only an important metabolite that provides additional energy to brain tissue during recovery from stroke under conditions of mitochondrial damage but also an important signaling molecule that supports neuronal plasticity and reduces neuroinflammation. Full article

8-oxoguanine (oxoG) is formed in DNA by the action of reactive oxygen species. As a highly mutagenic and the most common oxidative DNA lesion, it is an important marker of oxidative stress. Human 8-oxoguanine-DNA glycosylase (OGG1) is responsible for its prompt removal in human cells. OGG1 is a bifunctional DNA glycosylase with N-glycosylase and AP lyase activities. Aspects of the detailed mechanism underlying the recognition of 8-oxoguanine among numerous intact bases and its subsequent interaction with the enzyme’s active site amino acid residues are still debated. The main objective of our work was to determine the effect (structural and thermodynamic) of introducing an oxoG-clamp in model DNA substrates on the process of 8-oxoG excision by OGG1. Towards that end, we used DNA duplexes modeling OGG1-specific lesions: 8-oxoguanine or an apurinic/apyrimidinic site with either cytidine or the oxoG-clamp in the complementary strand opposite to the lesion. It was revealed that there was neither hydrolysis of the N-glycosidic bond at oxoG nor cleavage of the sugar–phosphate backbone during the reaction between OGG1 and oxoG-clamp-containing duplexes. Possible structural reasons for the absence of OGG1 enzymatic activity were studied via the stopped-flow kinetic approach and molecular dynamics simulations. The base opposite the damage was found to have a critical effect on the formation of the enzyme–substrate complex and the initiation of DNA cleavage. The oxoG-clamp residue prevented the eversion of the oxoG base into the OGG1 active site pocket and impeded the correct convergence of the apurinic/apyrimidinic site of DNA and the attacking nucleophilic group of the enzyme. An obtained three-dimensional model of the OGG1 complex with DNA containing the oxoG-clamp, together with kinetic data, allowed us to clarify the role of the contact of amino acid residues with DNA in the formation of (and rearrangements in) the enzyme–substrate complex. Full article

1-Deoxynojirimycin (DNJ) is a type of alkaloid that mainly exists in mulberry fruit and leaves. DNJ inhibits α-glucosidase, reduces the absorption of sugar, and suppresses after-meal hyperglycemia. It was reported that DNJ functions in attenuating cellular oxidative stress. However, the mechanisms remain largely unknown. In this study, we firstly confirmed that 5 µmol/L DNJ treatment mitigated the oxidative DNA damage and cell senescence in human umbilical vein endothelial cells (HUVEC) cultured in medium containing 50 mmol/L glucose. Next, we found that DNJ treatment stimulates the expression of anti-oxidative response regulator, Nuclear factor (erythroid-derived 2)-like 2 (NRF2) by around 50% in cells cultured with high glucose. In addition, 8-oxoguanine DNA glycosylase (OGG1) was upregulated by over 15% after DNJ treatment to mitigate high-glucose-induced oxidative DNA damage, and it was identified as a downstream target of NRF2. Further, DNJ treatment promoted the phosphorylation and activation of AKT (ser473) by around 50% in cells cultured with high glucose, and AKT inhibitor treatment abrogated DNJ-induced upregulation of NRF2 and OGG1. Taken together, our results indicate that DNJ is an effective natural antioxidant in mitigating high-glucose-induced oxidative stress in HUVEC via activating the AKT-NRF2-OGG1 anti-oxidative response. Full article

Excessive consumption of food rich in saturated fatty acids and carbohydrates can lead to metabolic disturbances and cardiovascular disease. Hyperlipidemia is a significant risk factor for acute cardiac events due to its association with oxidative stress. This leads to arterial wall remodeling, including an increase in the thickness of the intima media complex (IMT), and endothelial dysfunction leading to plaque formation. The decreased nitric oxide synthesis and accumulation of lipids in the wall result in a reduction in the vasodilating potential of the vessel. This study aimed to establish a clear relationship between markers of endothelial dysfunction and the activity of repair enzymes in cardiac tissue from a pig model of early atherosclerosis. The study was conducted on 28 female Polish Landrace pigs, weighing 40 kg (approximately 3.5 months old), which were divided into three groups. The control group (n = 11) was fed a standard, commercial, balanced diet (BDG) for 12 months. The second group (n = 9) was fed an unbalanced, high-calorie Western-type diet (UDG). The third group (n = 8) was fed a Western-type diet for nine months and then switched to a standard, balanced diet (regression group, RG). Control examinations, including blood and urine sampling, were conducted every three months under identical conditions with food restriction for 12 h and water restriction for four hours before general anesthesia. The study analyzed markers of oxidative stress formed during lipid peroxidation processes, including etheno DNA adducts, ADMA, and NEFA. These markers play a crucial role in reactive oxygen species analysis in ischemia–reperfusion and atherosclerosis in mammalian tissue. Essential genes involved in oxidative-stress-induced DNA demethylation like OGG1 (8-oxoguanine DNA glycosylase), MPG (N-Methylpurine DNA Glycosylase), TDG (Thymine-DNA glycosylase), APEX (apurinic/apirymidinic endodeoxyribonuclease 1), PTGS2 (prostaglandin-endoperoxide synthase 2), and ALOX (Arachidonate Lipoxygenase) were measured using the Real-Time RT-PCR method. The data suggest that high oxidative stress, as indicated by TBARS levels, is associated with high levels of DNA repair enzymes and depends on the expression of genes involved in the repair pathway. In all analyzed groups of heart tissue homogenates, the highest enzyme activity and gene expression values were observed for the OGG1 protein recognizing the modified 8oxoG. Conclusion: With the long-term use of an unbalanced diet, the levels of all DNA repair genes are increased, especially (significantly) Apex, Alox, and Ptgs, which strongly supports the hypothesis that an unbalanced diet induces oxidative stress that deregulates DNA repair mechanisms and may contribute to genome instability and tissue damage. Full article

Several modifiable risk factors for neurodegeneration and dementia have been identified, although individuals vary in their vulnerability despite a similar risk of exposure. This difference in vulnerability could be explained at least in part by the variability in DNA repair mechanisms’ efficiency between individuals. Therefore, the aim of this study was to test associations between documented, prevalent genetic variation (single nucleotide polymorphism, SNP) in DNA repair genes, cognitive function, and brain structure. Community-living participants (n = 488,159; 56.54 years (8.09); 54.2% female) taking part in the UK Biobank study and for whom cognitive and genetic measures were available were included. SNPs in base excision repair (BER) genes of the bifunctional DNA glycosylases OGG1 (rs1052133, rs104893751), NEIL1 (rs7402844, rs5745906), NEIL2 (rs6601606), NEIL3 (rs10013040, rs13112390, rs13112358, rs1395479), MUTYH (rs34612342, rs200165598), NTHL1 (rs150766139, rs2516739) were considered. Cognitive measures included fluid intelligence, the symbol–digit matching task, visual matching, and trail-making. Hierarchical regression and latent class analyses were used to test the associations between SNPs and cognitive measures. Associations between SNPs and brain measures were also tested in a subset of 39,060 participants. Statistically significant associations with cognition were detected for 12 out of the 13 SNPs analyzed. The strongest effects amounted to a 1–6% difference in cognitive function detected for NEIL1 (rs7402844), NEIL2 (rs6601606), and NTHL1 (rs2516739). Associations varied by age and sex, with stronger effects detected in middle-aged women. Weaker associations with brain measures were also detected. Variability in some BER genes is associated with cognitive function and brain structure and may explain variability in the risk for neurodegeneration and dementia. Full article

Hydroxyhydroquinone (HHQ) is an oxidative component produced by roasting coffee beans and has been reported to generate relatively large amounts of reactive oxygen species (ROS). In this study, we used senescence-accelerated mouse prone 8 (SAMP8) mice to determine whether HHQ consumption increases oxidative-stress-induced injury, because in SAMP8 mice, the activity of 8-oxoguanine DNA glycosylase 1, which repairs oxidative modifications in DNA, is decreased. The results showed that two out of twelve (16.7%) HHQ-treated mice presented polyuria and glucosuria around 2 months after the start of treatment, indicating that HHQ may act as a mutagen against SAMP8 mice, which is sensitive to oxidative damage. No abnormalities were observed in the chlorogenic acid (coffee polyphenol, CPP)-treated group. The concentration of hydrogen peroxide in the serum of SAMP8 mice was significantly higher than that in SAMR1 (senescence-resistant) control mice, and the concentration was further increased in the HHQ-treated group. CPP, when coexisting with HHQ at the rate contained in roasted coffee, decreased the amount of hydrogen peroxide in the serum of SAMP8 mice. Although CPP can act both oxidatively and antioxidatively as a polyphenol, CPP acts more antioxidatively when coexisting with HHQ. Thus, the oxidative effect of HHQ was shown to be counteracted by CPP. Full article