RESUMO
Reactive oxygen species (ROS)-induced oxidative DNA damages have been considered the main cause of mutations in genes, which are highly related to carcinogenesis and tumour progression. Extracellular vesicles play an important role in cancer metastasis. However, the precise role of DNA oxidative damage in extracellular vesicles (EVs)-mediated cancer cell migration and invasion remains unclear. Here, we reveal that ROS-mediated DNA oxidative damage signalling promotes tumour metastasis through increasing EVs release. Mechanistically, 8-oxoguanine DNA glycosylase (OGG1) recognises and binds to its substrate 8-oxo-7,8-dihydroguanine (8-oxoG), recruiting NF-κB to the synaptotagmin 7 (SYT7) promoter and thereby triggering SYT7 transcription. The upregulation of SYT7 expression leads to increased release of E-cadherin-loaded EVs, which depletes intracellular E-cadherin, thereby inducing epithelial-mesenchymal transition (EMT). Notably, Th5487, the inhibitor of DNA binding activity of OGG1, blocks the recognition and transmission of oxidative signals, alleviates SYT7 expression and suppresses EVs release, thereby preventing tumour progression in vitro and in vivo. Collectively, our study illuminates the significance of 8-oxoG/OGG1/SYT7 axis-driven EVs release in oxidative stress-induced tumour metastasis. These findings provide a deeper understanding of the molecular basis of cancer progression and offer potential avenues for therapeutic intervention.
Assuntos
DNA Glicosilases , Vesículas Extracelulares , Metástase Neoplásica , Animais , Feminino , Humanos , Camundongos , Linhagem Celular Tumoral , Movimento Celular , Dano ao DNA , DNA Glicosilases/metabolismo , Transição Epitelial-Mesenquimal , Vesículas Extracelulares/metabolismo , Guanina/análogos & derivados , Guanina/metabolismo , NF-kappa B/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Transdução de SinaisRESUMO
The human glycosylase OGG1 extrudes and excises the oxidized DNA base 8-oxoguanine (8-oxoG) to initiate base excision repair and plays important roles in many pathological conditions such as cancer, inflammation, and neurodegenerative diseases. Previous structural studies have used a truncated protein and short linear DNA, so it has been unclear how full-length OGG1 operates on longer DNA or on nucleosomes. Here we report cryo-EM structures of human OGG1 bound to a 35-bp long DNA containing an 8-oxoG within an unmethylated Cp-8-oxoG dinucleotide as well as to a nucleosome with an 8-oxoG at super-helical location (SHL)-5. The 8-oxoG in the linear DNA is flipped out by OGG1, consistent with previous crystallographic findings with a 15-bp DNA. OGG1 preferentially binds near dsDNA ends at the nucleosomal entry/exit sites. Such preference may underlie the enzyme's function in DNA double-strand break repair. Unexpectedly, we find that OGG1 bends the nucleosomal entry DNA, flips an undamaged guanine, and binds to internal nucleosomal DNA sites such as SHL-5 and SHL+6. We suggest that the DNA base search mechanism by OGG1 may be chromatin context-dependent and that OGG1 may partner with chromatin remodelers to excise 8-oxoG at the nucleosomal internal sites.
Assuntos
DNA Glicosilases , DNA , Nucleossomos , DNA Glicosilases/metabolismo , DNA Glicosilases/química , Humanos , Nucleossomos/metabolismo , DNA/metabolismo , DNA/química , Ligação Proteica , Guanina/análogos & derivados , Guanina/metabolismo , Reparo do DNA , Microscopia CrioeletrônicaRESUMO
Although DNA methylation primarily represses TEs, it also represses select genes that are methylated in plant body tissues but demethylated by DNA glycosylases (DNGs) in endosperm or pollen. Either one of two DNGs, MATERNAL DEREPRESSION OF R1 (MDR1) or DNG102, is essential for pollen viability in maize. Using single-pollen mRNA sequencing on pollen-segregating mutations in both genes, we identify 58 candidate DNG target genes that account for 11.1% of the wild-type transcriptome but are silent or barely detectable in other tissues. They are unusual in their tendency to lack introns but even more so in their TE-like methylation (teM) in coding DNA. The majority have predicted functions in cell wall modification, and they likely support the rapid tip growth characteristic of pollen tubes. These results suggest a critical role for DNA methylation and demethylation in regulating maize genes with the potential for extremely high expression in pollen but constitutive silencing elsewhere.
Assuntos
DNA Glicosilases , Metilação de DNA , Regulação da Expressão Gênica de Plantas , Pólen , Zea mays , Zea mays/genética , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Pólen/genética , Pólen/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Mutação , Tubo Polínico/metabolismo , Tubo Polínico/genética , Tubo Polínico/crescimento & desenvolvimentoRESUMO
Sensitive monitoring of human 8-oxyguanine DNA glycosylase (hOGG1) activity in living cells is helpful to understand its function in damage repair and evaluate its role in disease diagnosis. Herein, a functional DNA-Zn2+ coordination nanospheres was proposed for sensitive imaging of hOGG1 in living cells. The nanospheres were constructed through the coordination-driven self-assembly of the entropy driven reaction (EDR) -deoxyribozyme (DNAzyme) system with Zn2+, where DNAzyme was designed to split structure and assembled into the EDR system. When the nanospheres entered the cell, the competitive coordination between phosphate in the cell and Zn2+ leaded to the disintegration of the nanospheres, releasing DNA and some Zn2+. The released Zn2+ acted as a cofactor of DNAzyme. In the presence of hOGG1, the EDR was completed, accompanied by fluorescence recovery and the generation of a complete DNAzyme. With the assistance of Zn2+, DNAzyme continuously cleaved substrates to produce plenty of fluorescence signals, thus achieving sensitive imaging of hOGG1 activity. The nanospheres successfully achieved sensitive imaging of hOGG1 in human cervical cancer cells (HeLa), human non-small cell lung cancer cells and human normal colonic epithelial cells, and assayed changes in hOGG1 activity in HeLa cells. This nanospheres may provide a new tool for intracellular hOGG1 imaging and related biomedical studies.
Assuntos
DNA Glicosilases , DNA Catalítico , Nanosferas , Zinco , Humanos , Nanosferas/química , Zinco/química , DNA Catalítico/química , DNA Catalítico/metabolismo , DNA Glicosilases/metabolismo , DNA Glicosilases/química , Células HeLa , Imagem Óptica , DNA/química , DNA/metabolismoRESUMO
BACKGROUND: Neuroblastoma, a pediatric malignancy, is significantly influenced by genetic factors. Prior research indicates that the OGG1 rs1052133 G > C polymorphism correlates with a decreased risk of neuroblastoma. METHODS: We analyzed 57 neuroblastoma and 21 adrenal samples, using immunohistochemistry to measure OGG1 and STUB1 expression levels. We conducted a survival analysis to explore relationship between the expressions and neuroblastoma prognosis. RESULTS: Notably higher OGG1 expression and significantly lower STUB1 expression in neuroblastoma. OGG1 levels were significantly correlated with patient age, tumor location, histological grade, Shimada classification, INSS stage, and risk category. A negative association was observed between OGG1 and STUB1 expressions. Higher OGG1 expression was linked to reduced PFS and OS. Lower STUB1 expression was associated with unfavorable PFS. Additionally, OGG1 expression and risk category emerged as independent predictors of prognosis. CONCLUSION: OGG1 potentially functions as an oncogene in NB, with its activity possibly modulated by STUB1 through the ubiquitination pathway.
Assuntos
DNA Glicosilases , Neuroblastoma , Ubiquitina-Proteína Ligases , Humanos , Neuroblastoma/genética , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Feminino , Masculino , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Pré-Escolar , Lactente , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Criança , Prognóstico , Ubiquitinação , Biomarcadores Tumorais/metabolismo , Biomarcadores Tumorais/genética , Reparo do DNARESUMO
A diverse antibody repertoire is essential for humoral immunity. Antibody diversification requires the introduction of deoxyuridine (dU) mutations within immunoglobulin genes to initiate somatic hypermutation (SHM) and class switch recombination (CSR). dUs are normally recognized and excised by the base excision repair (BER) protein uracil-DNA glycosylase 2 (UNG2). However, FAM72A downregulates UNG2 permitting dUs to persist and trigger SHM and CSR. How FAM72A promotes UNG2 degradation is unknown. Here, we show that FAM72A recruits a C-terminal to LisH (CTLH) E3 ligase complex to target UNG2 for proteasomal degradation. Deficiency in CTLH complex components result in elevated UNG2 and reduced SHM and CSR. Cryo-EM structural analysis reveals FAM72A directly binds to MKLN1 within the CTLH complex to recruit and ubiquitinate UNG2. Our study further suggests that FAM72A hijacks the CTLH complex to promote mutagenesis in cancer. These findings show that FAM72A is an E3 ligase substrate adaptor critical for humoral immunity and cancer development.
Assuntos
Switching de Imunoglobulina , Ubiquitina-Proteína Ligases , Humanos , Animais , Switching de Imunoglobulina/genética , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , Camundongos , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Células HEK293 , Ubiquitinação , Hipermutação Somática de Imunoglobulina/genética , Mutagênese , Reparo do DNA , Proteólise , Imunidade Humoral , Camundongos Endogâmicos C57BLRESUMO
OBJECTIVE: Inflammatory diseases are influenced by oxidative stress. Oxidatively damaged 8-oxoG in DNA is linked to inflammation. The enzyme OGG1 is responsible for repairing the damaged base in the DNA which is linked to pro-inflammatory signaling and severe inflammation. This study aims to explore the potential of targeting OGG1 as a therapeutic strategy in inflammatory disease conditions. METHODS: A comprehensive search and review of literature were conducted using appropriate scientific databases such as Google Scholar, Scopus, PubMed, Web of Science, and other references to obtain relevant information that suited the title and content of this article. RESULTS: Compelling pieces of evidence from many previous studies have shown the crucial role of the OGG1/8oxoG pathway in inflammatory disease conditions, leading to severe inflammatory response and death. Therefore, based on these pieces of evidence, targeting this enzyme (OGG1) using specific pharmacological inhibitors or interventions might lead to downregulation and amelioration of severe inflammation to reduce the morbimortality related to several disease conditions. CONCLUSION: This review highlighted the molecular mechanism of OGG1 activity via the 8-oxo/OGG1 pathway and its role in inflammation and inflammatory disease conditions. Due to the paucity of studies involving OGG1in inflammatory infectious diseases, further research projects are needed to explore the therapeutic potential of various OGG1 inhibitors to serve as novel therapeutic strategies in infectious inflammatory diseases of medical importance in developing countries such as malaria, meningitis, tuberculosis among others.
Assuntos
DNA Glicosilases , Inflamação , Humanos , DNA Glicosilases/antagonistas & inibidores , DNA Glicosilases/metabolismo , Inflamação/tratamento farmacológico , Inflamação/imunologia , Animais , Estresse Oxidativo/efeitos dos fármacosRESUMO
DNA glycosylases initiate the base excision repair (BER) pathway by catalyzing the removal of damaged or mismatched bases from DNA. The Arabidopsis DNA glycosylase methyl-CpG-binding domain protein 4 like (MBD4L) is a nuclear enzyme triggering BER in response to the genotoxic agents 5-fluorouracil and 5-bromouracil. To date, the involvement of MBD4L in plant physiological processes has not been analyzed. To address this, we studied the enzyme functions in seeds. We found that imbibition induced the MBD4L gene expression by generating two alternative transcripts, MBD4L.3 and MBD4L.4. Gene activation was stronger in aged than in non-aged seeds. Seeds from mbd4l-1 mutants displayed germination failures when maintained under control or ageing conditions, while 35S:MBD4L.3/mbd4l-1 and 35S:MBD4L.4/mbd4l-1 seeds reversed these phenotypes. Seed nuclear DNA repair, assessed by comet assays, was exacerbated in an MBD4L-dependent manner at 24 h post-imbibition. Under this condition, the BER genes ARP, APE1L, and LIG1 showed higher expression in 35S:MBD4L.3/mbd4l-1 and 35S:MBD4L.4/mbd4l-1 than in mbd4l-1 seeds, suggesting that these components could coordinate with MBD4L to repair damaged DNA bases in seeds. Interestingly, the ATM, ATR, BRCA1, RAD51, and WEE1 genes associated with the DNA damage response (DDR) pathway were activated in mbd4l-1, but not in 35S:MBD4L.3/mbd4l-1 or 35S:MBD4L.4/mbd4l-1 seeds. These results indicate that MBD4L is a key enzyme of a BER cascade that operates during seed imbibition, whose deficiency would cause genomic damage detected by DDR, generating a delay or reduction in germination.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , DNA Glicosilases , Reparo do DNA , Germinação , Sementes , Sementes/genética , Sementes/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Regulação da Expressão Gênica de Plantas , Dano ao DNARESUMO
Maintaining the integrity of the genome is fundamental to living organisms. To this end, nature developed several mechanisms to find and promptly repair DNA lesions. Among them, base excision repair (BER) enzymes evolved to efficiently carry out this task. Notably, the mechanisms allowing these proteins to search for, detect, and fix DNA damage on a biologically relevant time scale still remain partially unclear. By taking MutY, a BER enzyme implied in the repair of the 8-oxoguanine-adenine mismatches, as a model system, we shed some light on the repair mechanism through a theoretical-computational approach. First, we estimated the effect of the oxidation state of the MutY iron-sulfur cluster on the protein-DNA binding. Then, the redox thermodynamics of both the protein cluster and DNA nucleobases are calculated. Finally, the charge migration kinetics along the double strand bound to the enzyme has been evaluated. The rationalization of our results indicates that the search for DNA lesions is essentially dictated by the redox chemistry of the species involved, i.e., the iron-sulfur redox cofactor and the DNA bound to the enzyme.
Assuntos
DNA Glicosilases , Reparo do DNA , Oxirredução , DNA Glicosilases/metabolismo , DNA Glicosilases/química , Reparo do DNA/fisiologia , DNA/metabolismo , DNA/química , Cinética , Dano ao DNA , Termodinâmica , Proteínas Ferro-Enxofre/metabolismo , Proteínas Ferro-Enxofre/química , Proteínas Ferro-Enxofre/genéticaRESUMO
Relatively low levels of antioxidant enzymes coupled with high oxygen metabolism result in the formation of numerous oxidative DNA damages in the tissues of the central nervous system. Recently, kynurenic acid (KYNA), knowns for its neuroprotective properties, has gained increasing attention in this context. Therefore, our hypothesis assumed that increased KYNA levels in the brain would positively influence mRNA expression of selected enzymes of the base excision repair pathway as well as enhance their efficiency in excising damaged nucleobases in specific areas of the sheep brain. The study was conducted on adult anestrous sheep (n = 18), in which two different doses of KYNA (20 and 100 µg/day) were infused into the third brain ventricle for three days. Molecular and biochemical analysis included the hypothalamus (preoptic and mediol-basal areas), hippocampus (CA3 field) and amygdala (central amygdaloid nucleus), dissected from the brain of sheep euthanized immediately after the last infusion. The results revealed a significant increase P < 0.001) in the relative mRNA abundance of N-methylpurine DNA glycosylase (MPG) following administration of both dose of KYNA across all examined tissues. The transcription of thymine-DNA glycosylase (TDG) increased significantly (P < 0.001) in all tissues in response to the lower KYNA dose compared to the control group. Moreover, 8-oxoguanine (8-oxoG) DNA glycosylase (OGG1) mRNA levels were also higher in both animal groups (P < 0.001). In addition, in the hypothalamus, hippocampus and amygdala, AP endonuclease 1 (APE1) mRNA expression increased under both doses of KYNA. Moreover, the both dose of KYNA significantly stimulated the efficiency of 8-oxoG excision in hypothalamus and amygdala (P < 0.05-0.001). The lower and higher doses of KYNA significantly influenced the effectiveness of εA and εC in all structures (P < 0.01-0.001). In conclusion, the favorable effect of KYNA in the brain may include the protection of genetic material in nerve and glial cells by stimulating the expression and efficiency of BER pathway enzymes.
Assuntos
Encéfalo , DNA Glicosilases , Reparo do DNA , Ácido Cinurênico , Animais , Reparo do DNA/efeitos dos fármacos , Ovinos , Ácido Cinurênico/metabolismo , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Encéfalo/metabolismo , Encéfalo/efeitos dos fármacos , Hipotálamo/metabolismo , Hipotálamo/efeitos dos fármacos , RNA Mensageiro/metabolismo , RNA Mensageiro/genética , Dano ao DNA/efeitos dos fármacos , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Feminino , Hipocampo/metabolismo , Hipocampo/efeitos dos fármacos , Reparo por ExcisãoRESUMO
African swine fever virus (ASFV), as a contagious viral pathogen, is responsible for the occurrence of African swine fever (ASF), a rapidly spreading and highly lethal disease. Since ASFV was introduced into China in 2018, it has been quickly spread to many provinces, which brought great challenges to the pig industry in China. Due to the limited knowledge about the pathogenesis of ASFV, neither vaccines nor antiviral drugs are available. We have found that ASFV infection can induce oxidative stress responses in cells, and DNA repair enzymes play a key role in this process. This study employed RNA interference, RT-qPCR, Western blotting, Hemadsorption (HAD), and flow cytometry to investigate the effects of the inhibitors of DNA repair enzymes OGG1 and MTH1 on ASFV replication and evaluated the anti-ASFV effects of the inhibitors. This study provides reference for the development of anti-viral drugs.
Assuntos
Vírus da Febre Suína Africana , DNA Glicosilases , Monoéster Fosfórico Hidrolases , Replicação Viral , Vírus da Febre Suína Africana/genética , Vírus da Febre Suína Africana/efeitos dos fármacos , Animais , Replicação Viral/efeitos dos fármacos , Suínos , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Monoéster Fosfórico Hidrolases/genética , Monoéster Fosfórico Hidrolases/antagonistas & inibidores , Monoéster Fosfórico Hidrolases/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Febre Suína Africana/virologia , Antivirais/farmacologia , Interferência de RNA , RNA Interferente Pequeno/genética , Inibidores Enzimáticos/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Células VeroRESUMO
Two guanine base editors created using an engineered N-methylpurine DNA glycosylase with CRISPR systems achieved targeted G-to-T editing with 4.94-12.50% efficiency in rice (Oryza sativa). The combined use of the DNA glycosylase and deaminases enabled co-editing of target guanines with adenines or cytosines.
Assuntos
Edição de Genes , Guanina , Oryza , Oryza/genética , Edição de Genes/métodos , Guanina/metabolismo , Sistemas CRISPR-Cas/genética , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Timina/metabolismoRESUMO
CTC1-STN1-TEN1 (CST) is a single-stranded DNA binding protein vital for telomere length maintenance with additional genome-wide roles in DNA replication and repair. While CST was previously shown to function in double-strand break repair and promote replication restart, it is currently unclear whether it has specialized roles in other DNA repair pathways. Proper and efficient repair of DNA is critical to protecting genome integrity. Telomeres and other G-rich regions are strongly predisposed to oxidative DNA damage in the form of 8-oxoguanines, which are typically repaired by the base-excision repair (BER) pathway. Moreover, recent studies suggest that CST functions in the repair of oxidative DNA lesions. Therefore, we tested whether CST interacts with and regulates BER protein activity. Here, we show that CST robustly stimulates proteins involved in BER, including OGG1, Pol ß, APE1, and LIGI, on both telomeric and non-telomeric DNA substrates. Biochemical reconstitution of the pathway indicates that CST stimulates BER. Finally, knockout of STN1 or CTC1 leads to increased levels of 8-oxoguanine, suggesting defective BER in the absence of CST. Combined, our results define an undiscovered function of CST in BER, where it acts as a stimulatory factor to promote efficient genome-wide oxidative repair.
Assuntos
Dano ao DNA , Reparo do DNA , Proteínas de Ligação a Telômeros , Humanos , Proteínas de Ligação a Telômeros/metabolismo , Proteínas de Ligação a Telômeros/genética , Telômero/metabolismo , Telômero/genética , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Estresse Oxidativo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/metabolismo , DNA Liase (Sítios Apurínicos ou Apirimidínicos)/genética , Guanina/análogos & derivados , Guanina/metabolismo , DNA Polimerase beta/metabolismo , DNA Polimerase beta/genética , Reparo por ExcisãoRESUMO
Diabetic cardiomyopathy (DCM) is a heart failure syndrome, and is one of the major causes of morbidity and mortality in diabetes. DCM is mainly characterized by ventricular dilation, myocardial hypertrophy, myocardial fibrosis and cardiac dysfunction. Clinical studies have found that insulin resistance is an independent risk factor for DCM. However, its specific mechanism of DCM remains unclear. 8-hydroxyguanine DNA glycosylase 1(OGG1)is involved in DNA base repair and the regulation of inflammatory genes. In this study, we show that OGG1 was associated with the occurrence of DCM. for the first time. The expression of OGG1 was increased in the heart tissue of DCM mice, and OGG1 deficiency aggravated the cardiac dysfunction of DCM mice. Metabolomics show that OGG1 deficiency resulted in obstruction of glycolytic pathway. At the molecular level, OGG1 regulated glucose uptake and insulin resistance by interacting with PPAR-γ in vitro. In order to explore the protective effect of exogenous OGG1 on DCM, OGG1 adeno-associated virus was injected into DCM mice through tail vein in the middle stage of the disease. We found that the overexpression of OGG1 could improve cardiac dysfunction of DCM mice, indicating that OGG1 had a certain therapeutic effect on DCM. These results demonstrate that OGG1 is a new molecular target for the treatment of DCM and has certain clinical significance.
Assuntos
DNA Glicosilases , Cardiomiopatias Diabéticas , Resistência à Insulina , Animais , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , DNA Glicosilases/deficiência , Cardiomiopatias Diabéticas/metabolismo , Cardiomiopatias Diabéticas/etiologia , Cardiomiopatias Diabéticas/genética , Cardiomiopatias Diabéticas/patologia , Camundongos , Masculino , PPAR gama/metabolismo , Glucose/metabolismo , Miocárdio/metabolismo , Miocárdio/patologia , Modelos Animais de Doenças , Glicólise , Humanos , Camundongos Endogâmicos C57BLRESUMO
AIM: To identify mtDNA and OGG1 as potential biomarker candidates for mechanical asphyxia. METHOD: The human tissues are divided into experimental group (hanging and strangulation) and control groups (hemorrhagic shock, brain injury group, and poisoning group). Detected the expression of OGG1 and integrity of mtDNA in cardiac tissue of each group. We used over-OGG1 vector and siRNA-OGG1 transfecting H9C2 cell line to observe the function of OGG1 in hypoxic cells. RESULTS: 1. mtDNA integrity decreased in the mechanical asphyxia group, OGG1 expression increased in mechanical asphyxia groups. They can be biomarkers for mechanical asphyxia. 2. OGG1 increased first and decreased in hypoxia-induced H9C2 cells. OGG1 upregulated the TFAM, NRF1, and Bcl2 in hypoxia-induced H9C2. OGG1 downregulated cleaved-Caspase3 in hypoxia-induced H9C2 cells. 3. In the normoxia condition, NAC maintained mtDNA integrity and decreased the mitochondrial membrane potential and amount of ATP. CONCLUSION: mtDNA integrity and OGG1 expression can be biomarkers for mechanical asphyxia. OGG1 can maintain mtDNA integrity and maintain the stability of the mitochondrial membrane.
Assuntos
Asfixia , Biomarcadores , DNA Glicosilases , DNA Mitocondrial , DNA Glicosilases/metabolismo , Humanos , DNA Mitocondrial/metabolismo , Biomarcadores/metabolismo , Asfixia/metabolismo , Linhagem Celular , Potencial da Membrana Mitocondrial , Animais , Miocárdio/metabolismo , MasculinoRESUMO
Maintenance of DNA integrity is essential to all forms of life. DNA damage generated by reaction with genotoxic chemicals results in deleterious mutations, genome instability, and cell death. Pathogenic bacteria encounter several genotoxic agents during infection. In keeping with this, the loss of DNA repair networks results in virulence attenuation in several bacterial species. Interstrand DNA crosslinks (ICLs) are a type of DNA lesion formed by covalent linkage of opposing DNA strands and are particularly toxic as they interfere with replication and transcription. Bacteria have evolved specialized DNA glycosylases that unhook ICLs, thereby initiating their repair. In this study, we describe AlkX, a DNA glycosylase encoded by the multidrug resistant pathogen Acinetobacter baumannii. AlkX exhibits ICL unhooking activity similar to that of its Escherichia coli homolog YcaQ. Interrogation of the in vivo role of AlkX revealed that its loss sensitizes cells to DNA crosslinking and impairs A. baumannii colonization of the lungs and dissemination to distal tissues during pneumonia. These results suggest that AlkX participates in A. baumannii pathogenesis and protects the bacterium from stress conditions encountered in vivo. Consistent with this, we found that acidic pH, an environment encountered during host colonization, results in A. baumannii DNA damage and that alkX is induced by, and contributes to, defense against acidic conditions. Collectively, these studies reveal functions for a recently described class of proteins encoded in a broad range of pathogenic bacterial species.
Assuntos
Acinetobacter baumannii , Dano ao DNA , DNA Glicosilases , Acinetobacter baumannii/patogenicidade , Acinetobacter baumannii/genética , Acinetobacter baumannii/enzimologia , Acinetobacter baumannii/metabolismo , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Reparo do DNA , Infecções por Acinetobacter/microbiologia , Infecções por Acinetobacter/patologia , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Animais , Camundongos , DNA Bacteriano/genética , DNA Bacteriano/metabolismo , Virulência , Escherichia coli/genética , Escherichia coli/metabolismoRESUMO
Ivermectin (IVM) is an anti-parasitic drug which is used for treating parasitic infestations. It has been used in humans for treating intestinal strongyloidiasis and onchocerciasis however, currently researchers are investigating its potential for treating coronavirus SARS-CoV-2. Due to its broad-spectrum activities, IVM is being used excessively in animals which has generated an interest for researchers to investigate its toxic effects. Cytotoxic and genotoxic effects have been reported in animals due to excessive usage of IVM. Therefore, this study aims to evaluate the cytotoxic and genotoxic effects of IVM on the Madin-Darby-Bovine-Kidney (MDBK) cell line by examining the expression of a DNA damage-responsive gene (OGG1). Cytotoxicity of IVM was tested using an assay (MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), whereas the genotoxicity was evaluated using comet assay along with micronucleus assay. Moreover, the gene expression of DNA damage response gene (OGG1) was measured by qRT-PCR, after extraction of RNA from the MDBK cell line using the TRIzol method and its conversion to cDNA by reverse-transcriptase PCR. During the experiment, cell viability percentage was measured at different doses of IVM i.e., 25%, 50%, 75%, along with LC50/2, LC50 and LC50*2. It was observed that the gene expression of OGG1 increased as the concentration of IVM increased. It was concluded that IVM has both cytotoxic and genotoxic effects on the MDBK cell line. Furthermore, it is recommended that studies related to the toxic effects of IVM at molecular level and on other model organisms should be conducted to combat its hazardous effects.
Assuntos
Dano ao DNA , Ivermectina , Ivermectina/toxicidade , Ivermectina/farmacologia , Animais , Dano ao DNA/efeitos dos fármacos , Linhagem Celular , Bovinos , Sobrevivência Celular/efeitos dos fármacos , Testes para Micronúcleos , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Ensaio Cometa , Mutagênicos/toxicidade , Antiparasitários/farmacologia , Antiparasitários/toxicidade , Rim/efeitos dos fármacos , Rim/citologiaRESUMO
BACKGROUND: 8-Oxoguanine DNA glycosylase (OGG1), a well-known DNA repair enzyme, has been demonstrated to promote lung fibrosis, while the specific regulatory mechanism of OGG1 during pulmonary fibrosis remains unclarified. METHODS: A bleomycin (BLM)-induced mouse pulmonary fibrosis model was established, and TH5487 (the small molecule OGG1 inhibitor) and Mitochondrial division inhibitor 1 (Mdivi-1) were used for administration. Histopathological injury of the lung tissues was assessed. The profibrotic factors and oxidative stress-related factors were examined using the commercial kits. Western blot was used to examine protein expression and immunofluorescence analysis was conducted to assess macrophages polarization and autophagy. The conditional medium from M2 macrophages was harvested and added to HFL-1 cells for culture to simulate the immune microenvironment around fibroblasts during pulmonary fibrosis. Subsequently, the loss- and gain-of function experiments were conducted to further confirm the molecular mechanism of OGG1/PINK1. RESULTS: In BLM-induced pulmonary fibrosis, OGG1 was upregulated while PINK1/Parkin was downregulated. Macrophages were activated and polarized to M2 phenotype. TH5487 administration effectively mitigated pulmonary fibrosis, M2 macrophage polarization, oxidative stress and mitochondrial dysfunction while promoted PINK1/Parkin-mediated mitophagy in lung tissues of BLM-induced mice, which was partly hindered by Mdivi-1. PINK1 overexpression restricted M2 macrophages-induced oxidative stress, mitochondrial dysfunction and mitophagy inactivation in lung fibroblast cells, and OGG1 knockdown could promote PINK1/Parkin expression and alleviate M2 macrophages-induced mitochondrial dysfunction in HFL-1 cells. CONCLUSION: OGG1 inhibition protects against pulmonary fibrosis, which is partly via activating PINK1/Parkin-mediated mitophagy and retarding M2 macrophage polarization, providing a therapeutic target for pulmonary fibrosis.
Assuntos
Bleomicina , DNA Glicosilases , Modelos Animais de Doenças , Macrófagos , Mitofagia , Proteínas Quinases , Fibrose Pulmonar , Animais , Mitofagia/efeitos dos fármacos , Fibrose Pulmonar/metabolismo , Fibrose Pulmonar/induzido quimicamente , Fibrose Pulmonar/etiologia , Fibrose Pulmonar/patologia , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , Camundongos , Macrófagos/metabolismo , Proteínas Quinases/metabolismo , Bleomicina/efeitos adversos , Masculino , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitina-Proteína Ligases/genética , Estresse Oxidativo/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Ativação de Macrófagos , Humanos , QuinazolinonasRESUMO
The base excision repair (BER) pathway is a precise and versatile mechanism of DNA repair that is initiated by DNA glycosylases. Endonuclease VIII-like 1 (NEIL1) is a bifunctional glycosylase/abasic site (AP) lyase that excises a damaged base and subsequently cleaves the phosphodiester backbone. NEIL1 is able to recognize and hydrolyze a broad range of oxidatively-induced base lesions and substituted ring-fragmented guanines, including aflatoxin-induced 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl-formamido)-9-hydroxyaflatoxin B1 (AFB1-FapyGua). Due to NEIL1's protective role against these and other pro-mutagenic lesions, it was hypothesized that naturally occurring single nucleotide polymorphic (SNP) variants of NEIL1 could increase human risk for aflatoxin-induced hepatocellular carcinoma (HCC). Given that populations in South Asia experience high levels of dietary aflatoxin exposures and hepatitis B viral infections that induce oxidative stress, investigations on SNP variants of NEIL1 that occur in this region may have clinical implications. In this study, the most common South Asian variants of NEIL1 were expressed, purified, and functionally characterized. All tested variants exhibited activities and substrate specificities similar to wild type (wt)-NEIL1 on high-molecular weight DNA containing an array of oxidatively-induced base lesions. On short oligodeoxynucleotides (17-mers) containing either a site-specific apurinic/apyrimidinic (AP) site, thymine glycol (ThyGly), or AFB1-FapyGua, P206L-NEIL1 was catalytically comparable to wt-NEIL1, while the activities of NEIL1 variants Q67K and T278I on these substrates were ≈2-fold reduced. Variant T103A had a greatly diminished ability to bind to 17-mer DNAs, limiting the subsequent glycosylase and lyase reactions. Consistent with this observation, the rate of excision by T103A on 17-mer oligodeoxynucleotides containing ThyGly or AFB1-FapyGua could not be measured. However, the ability of T103A to excise ThyGly was improved on longer oligodeoxynucleotides (51-mers), with ≈7-fold reduced activity compared to wt-NEIL1. Our studies suggest that NEIL1 variant T103A may present a pathogenic phenotype that is limited in damage recognition, potentially increasing human risk for HCC.
Assuntos
DNA Glicosilases , Reparo do DNA , Polimorfismo de Nucleotídeo Único , DNA Glicosilases/metabolismo , DNA Glicosilases/genética , DNA Glicosilases/química , Humanos , Aflatoxina B1/metabolismo , Dano ao DNA , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/enzimologia , Especificidade por Substrato , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/enzimologiaRESUMO
Over the past decades, cancer stem cells (CSCs) have emerged as a critical subset of tumor cells associated with tumor recurrence and resistance to chemotherapy. Understanding the mechanisms underlying CSC-mediated chemoresistance is imperative for improving cancer therapy outcomes. This study delves into the regulatory role of NEIL1, a DNA glycosylase, in chemoresistance in ovarian CSCs. We first observed a decreased expression of NEIL1 in ovarian CSCs, suggesting its potential involvement in CSC regulation. Using pan-cancer analysis, we confirmed the diminished NEIL1 expression in ovarian tumors compared to normal tissues. Furthermore, NEIL1 downregulation correlated with an increase in stemness markers and enrichment of CSCs, highlighting its role in modulating CSC phenotype. Further mechanistic investigation revealed an inverse correlation between NEIL1 and RAD18 expression in ovarian CSCs. NEIL1 depletion led to heightened RAD18 expression, promoting chemoresistance possibly via enhancing Translesion DNA Synthesis (TLS)-mediated DNA lesion bypass. Moreover, dowregulation of NEIL1 results in reduced DNA damage accumulation and suppressed apoptosis in ovarian cancer. Overall, our findings unveil a novel mechanism involving NEIL1 and RAD18 in regulating chemoresistance in ovarian CSCs. Targeting this NEIL1-RAD18 axis may offer promising therapeutic strategies for combating chemoresistance and improving ovarian cancer treatment outcomes.