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Toxicological Sciences : An Official... Nov 2022Methylmercury (MeHg) persists today as a priority public health concern. Mechanisms influencing MeHg metabolism, kinetics, and toxicity outcomes are therefore essential...
Methylmercury (MeHg) persists today as a priority public health concern. Mechanisms influencing MeHg metabolism, kinetics, and toxicity outcomes are therefore essential knowledge for informing exposure risks. Evidence points to different toxic potencies of MeHg and inorganic mercury (Hg2+), highlighting the role for biotransformation (demethylation) in regulating MeHg toxicokinetics/dynamics. Whereas microbial MeHg demethylation in the gut is seen to influence elimination kinetics, the potential for systemic demethylation in tissues and target organs to influence MeHg toxicity remains uncertain. To investigate the consequences of systemic MeHg demethylation across development, we engineered transgenic Drosophila to express the bacterial organomercurial lyase enzyme (merB) in a targeted and tissue-specific manner. With all combinations of merB-induced demethylation, ubiquitously (via an actin promoter) or in a tissue-specific manner (ie, gut, muscle, neurons), we observe a rescue of MeHg-induced eclosion failure at the pupal to adult transition. In MeHg-fed larvae with ubiquitous or targeted (gut and muscle) merB expression, we see a significant decrease in MeHg body burden at the pupal stage relative to control flies. We also observe a significant increase in the MeHg elimination rate with merB demethylation induced in adults (control, t1/2 = 7.2 days; merB flies, t1/2 = 3.1 days). With neuronal-specific merB expression, we observe a rescue of MeHg-induced eclosion failure without a decrease in Hg body burden, but a redistribution of Hg away from the brain. These results demonstrate the previously unidentified potential for intracellular MeHg demethylation to promote transport and elimination of Hg, and reduce developmental MeHg toxicity. Impact Statement: These findings demonstrate the potential for MeHg demethylation in situ to contribute significantly to the MeHg elimination and distribution kinetics of whole animals and thereby affords a means of protection against the toxic insult of MeHg. Therefore, this study reveals important insight into processes that can determine an individual's resistance or susceptibility to MeHg and provides rationale for therapies targeting a novel metabolism-based pathways to alleviate toxicity risk stemming from MeHg exposure.
Topics: Animals; Methylmercury Compounds; Kinetics; Drosophila; Mercury; Animals, Genetically Modified; Demethylation
PubMed: 36200918
DOI: 10.1093/toxsci/kfac105 -
Experimental & Molecular Medicine Dec 2020Lysine-specific histone demethylase 1 (LSD1) represents the first example of an identified nuclear protein with histone demethylase activity. In particular, it plays a... (Review)
Review
Lysine-specific histone demethylase 1 (LSD1) represents the first example of an identified nuclear protein with histone demethylase activity. In particular, it plays a special role in the epigenetic regulation of gene expression, as it removes methyl groups from mono- and dimethylated lysine 4 and/or lysine 9 on histone H3 (H3K4me1/2 and H3K9me1/2), behaving as a repressor or activator of gene expression, respectively. Moreover, it has been recently found to demethylate monomethylated and dimethylated lysine 20 in histone H4 and to contribute to the balance of several other methylated lysine residues in histone H3 (i.e., H3K27, H3K36, and H3K79). Furthermore, in recent years, a plethora of nonhistone proteins have been detected as targets of LSD1 activity, suggesting that this demethylase is a fundamental player in the regulation of multiple pathways triggered in several cellular processes, including cancer progression. In this review, we analyze the molecular mechanism by which LSD1 displays its dual effect on gene expression (related to the specific lysine target), placing final emphasis on the use of pharmacological inhibitors of its activity in future clinical studies to fight cancer.
Topics: Alternative Splicing; Animals; Biomarkers, Tumor; Demethylation; Epigenesis, Genetic; Gene Expression Regulation; Histone Demethylases; Histones; Humans; Lysine; Molecular Targeted Therapy; Protein Binding; Protein Processing, Post-Translational; Protein Stability; Receptors, Cytoplasmic and Nuclear; Structure-Activity Relationship
PubMed: 33318631
DOI: 10.1038/s12276-020-00542-2 -
Mutation Research. Reviews in Mutation... 2021APE2 is a rising vital player in the maintenance of genome and epigenome integrity. In the past several years, a series of studies have shown the critical roles and... (Review)
Review
APE2 is a rising vital player in the maintenance of genome and epigenome integrity. In the past several years, a series of studies have shown the critical roles and functions of APE2. We seek to provide the first comprehensive review on several aspects of APE2 in genome and epigenome integrity. We first summarize the distinct functional domains or motifs within APE2 including EEP (endonuclease/exonuclease/phosphatase) domain, PIP box and Zf-GRF motifs from eight species (i.e., Homo sapiens, Mus musculus, Xenopus laevis, Ciona intestinalis, Arabidopsis thaliana, Schizosaccharomyces pombe, Saccharomyces cerevisiae, and Trypanosoma cruzi). Then we analyze various APE2 nuclease activities and associated DNA substrates, including AP endonuclease, 3'-phosphodiesterase, 3'-phosphatase, and 3'-5' exonuclease activities. We also examine several APE2 interaction proteins, including PCNA, Chk1, APE1, Myh1, and homologous recombination (HR) factors such as Rad51, Rad52, BRCA1, BRCA2, and BARD1. Furthermore, we provide insights into the roles of APE2 in various DNA repair pathways (base excision repair, single-strand break repair, and double-strand break repair), DNA damage response (DDR) pathways (ATR-Chk1 and p53-dependent), immunoglobulin class switch recombination and somatic hypermutation, as well as active DNA demethylation. Lastly, we summarize critical functions of APE2 in growth, development, and diseases. In this review, we provide the first comprehensive perspective which dissects all aspects of the multiple-function protein APE2 in genome and epigenome integrity.
Topics: Animals; Arabidopsis Proteins; DNA Damage; DNA Demethylation; DNA Repair; Endonucleases; Epigenome; Humans; Immunity; Rad51 Recombinase; Saccharomyces cerevisiae
PubMed: 34083046
DOI: 10.1016/j.mrrev.2020.108347 -
Cancer Cell Nov 2018Vitamin C (ascorbic acid, ascorbate), despite controversy, has re-emerged as a promising anti-cancer agent. Recent knowledge of intravenous ascorbate pharmacokinetics... (Review)
Review
Vitamin C (ascorbic acid, ascorbate), despite controversy, has re-emerged as a promising anti-cancer agent. Recent knowledge of intravenous ascorbate pharmacokinetics and discovery of unexpected mechanisms of ascorbate action have spawned many investigations. Two mechanisms of anti-cancer activity with ascorbate have gained prominence: hydrogen peroxide-induced oxidative stress and DNA demethylation mediated by ten-eleven translocation enzyme activation. Here, we highlight salient aspects of the evolution of ascorbate in cancer treatment, provide insights into the pharmacokinetics of ascorbate, describe mechanisms of its anti-cancer activity in relation to the pharmacokinetics, outline promising preclinical and clinical evidence, and recommend future directions.
Topics: Antineoplastic Agents; Antioxidants; Ascorbic Acid; DNA Demethylation; Humans; Hydrogen Peroxide; Mixed Function Oxygenases; Neoplasms; Oxidative Stress; Proto-Oncogene Proteins
PubMed: 30174242
DOI: 10.1016/j.ccell.2018.07.014 -
The Journal of Biological Chemistry Feb 2024Increased expression of angiotensin II AT receptor (encoded by Agtr1a) and Na-K-Cl cotransporter-1 (NKCC1, encoded by Slc12a2) in the hypothalamic paraventricular...
Increased expression of angiotensin II AT receptor (encoded by Agtr1a) and Na-K-Cl cotransporter-1 (NKCC1, encoded by Slc12a2) in the hypothalamic paraventricular nucleus (PVN) contributes to hypertension development. However, little is known about their transcriptional control in the PVN in hypertension. DNA methylation is a critical epigenetic mechanism that regulates gene expression. Here, we determined whether transcriptional activation of Agtr1a and Slc12a2 results from altered DNA methylation in spontaneously hypertensive rats (SHR). Methylated DNA immunoprecipitation and bisulfite sequencing-PCR showed that CpG methylation at Agtr1a and Slc12a2 promoters in the PVN was progressively diminished in SHR compared with normotensive Wistar-Kyoto rats (WKY). Chromatin immunoprecipitation-quantitative PCR revealed that enrichment of DNA methyltransferases (DNMT1 and DNMT3A) and methyl-CpG binding protein 2, a DNA methylation reader protein, at Agtr1a and Slc12a2 promoters in the PVN was profoundly reduced in SHR compared with WKY. By contrast, the abundance of ten-eleven translocation enzymes (TET1-3) at Agtr1a and Slc12a2 promoters in the PVN was much greater in SHR than in WKY. Furthermore, microinjecting of RG108, a selective DNMT inhibitor, into the PVN of WKY increased arterial blood pressure and correspondingly potentiated Agtr1a and Slc12a2 mRNA levels in the PVN. Conversely, microinjection of C35, a specific TET inhibitor, into the PVN of SHR markedly reduced arterial blood pressure, accompanied by a decrease in Agtr1a and Slc12a2 mRNA levels in the PVN. Collectively, our findings suggest that DNA hypomethylation resulting from the DNMT/TET switch at gene promoters in the PVN promotes transcription of Agtr1a and Slc12a2 and hypertension development.
Topics: Animals; Rats; Blood Pressure; DNA; DNA Demethylation; Hypertension; Hypothalamus; Paraventricular Hypothalamic Nucleus; Rats, Inbred SHR; Rats, Inbred WKY; Receptor, Angiotensin, Type 1; RNA, Messenger; Sympathetic Nervous System; Solute Carrier Family 12, Member 2
PubMed: 38160798
DOI: 10.1016/j.jbc.2023.105597 -
Scientific Reports Mar 2024As the most prevalent epitranscriptomic modification, N-methyladenosine (mA) shows important roles in a variety of diseases through regulating the processing, stability...
METTL3 and METTL14-mediated N-methyladenosine modification of SREBF2-AS1 facilitates hepatocellular carcinoma progression and sorafenib resistance through DNA demethylation of SREBF2.
As the most prevalent epitranscriptomic modification, N-methyladenosine (mA) shows important roles in a variety of diseases through regulating the processing, stability and translation of target RNAs. However, the potential contributions of mA to RNA functions are unclear. Here, we identified a functional and prognosis-related mA-modified RNA SREBF2-AS1 in hepatocellular carcinoma (HCC). The expression of SREBF2-AS1 and SREBF2 in HCC tissues and cells was measured by RT-qPCR. mA modification level of SREBF2-AS1 was measured by methylated RNA immunoprecipitation assay. The roles of SREBF2-AS1 in HCC progression and sorafenib resistance were investigated by proliferation, apoptosis, migration, and cell viability assays. The regulatory mechanisms of SREBF2-AS1 on SREBF2 were investigated by Chromatin isolation by RNA purification, RNA immunoprecipitation, CUT&RUN, and bisulfite DNA sequencing assays. Our findings showed that the expression of SREBF2-AS1 was increased in HCC tissues and cells, and positively correlated with poor survival of HCC patients. mA modification level of SREBF2-AS1 was also increased in HCC and positively correlated with poor prognosis of HCC patients. METTL3 and METTL14-induced mA modification upregulated SREBF2-AS1 expression through increasing SREBF2-AS1 transcript stability. Functional assays showed that only mA-modified, but not non-modified SREBF2-AS1 promoted HCC progression and sorafenib resistance. Mechanistic investigations revealed that mA-modified SREBF2-AS1 bound and recruited mA reader FXR1 and DNA 5-methylcytosine dioxygenase TET1 to SREBF2 promoter, leading to DNA demethylation at SREBF2 promoter and the upregulation of SREBF2 transcription. Functional rescue assays showed that SREBF2 was the critical mediator of the oncogenic roles of SREBF2-AS1 in HCC. Together, this study showed that mA-modified SREBF2-AS1 exerted oncogenic roles in HCC through inducing DNA demethylation and transcriptional activation of SREBF2, and suggested mA-modified SREBF2-AS1 as a prognostic biomarker and therapeutic target for HCC.
Topics: Humans; Carcinoma, Hepatocellular; Sorafenib; Liver Neoplasms; DNA Demethylation; Cell Line, Tumor; MicroRNAs; RNA-Binding Proteins; Mixed Function Oxygenases; Proto-Oncogene Proteins; Methyltransferases; Adenosine; Sterol Regulatory Element Binding Protein 2
PubMed: 38486042
DOI: 10.1038/s41598-024-55932-7 -
Oncogene Mar 2022Non-small cell lung cancer (NSCLC) is a fatal disease, and its metastatic process is poorly understood. Although aberrant methylation is involved in tumor progression,...
Non-small cell lung cancer (NSCLC) is a fatal disease, and its metastatic process is poorly understood. Although aberrant methylation is involved in tumor progression, the mechanisms underlying dynamic DNA methylation remain to be elucidated. It is significant to study the molecular mechanism of NSCLC metastasis and identify new biomarkers for NSCLC early diagnosis. Here, we performed MeDIP-seq and hMeDIP-seq analyses to detect the genes regulated by dynamic DNA methylation. Comparison of the 5mC and 5hmC sites revealed that the CD147 gene underwent active demethylation in NSCLC tissues compared with normal tissues, and this demethylation upregulated CD147 expression. Significantly high levels of CD147 expression and low levels of promoter methylation were observed in NSCLC tissues. Then, we identified the CD147 promoter as a target of KLF6, MeCP2, and DNMT3A. Treatment of cells with TGF-β triggered active demethylation involving loss of KLF6/MeCP2/DNMT3A and recruitment of Sp1, Tet1, TDG, and SMAD2/3 transcription complexes. A dCas9-SunTag-DNMAT3A-sgCD147-targeted methylation system was constructed to reverse CD147 expression. The targeted methylation system downregulated CD147 expression and inhibited NSCLC proliferation and metastasis in vitro and in vivo. Accordingly, we used cfDNA to detect the levels of CD147 methylation in NSCLC tissues and found that the CD147 methylation levels exhibited an inverse relationship with tumor size, lymphatic metastasis, and TNM stage. In conclusion, this study clarified the mechanism of active demethylation of CD147 and suggested that the targeted methylation of CD147 could inhibit NSCLC invasion and metastasis, providing a highly promising therapeutic target for NSCLC.
Topics: Carcinoma, Non-Small-Cell Lung; Cell Line, Tumor; DNA Methylation; Demethylation; Gene Expression Regulation, Neoplastic; Humans; Lung Neoplasms; Mixed Function Oxygenases; Proto-Oncogene Proteins
PubMed: 35132181
DOI: 10.1038/s41388-022-02213-0 -
Science (New York, N.Y.) Dec 2022Active DNA demethylation maintains enhancer activity in nonproliferating cells but can damage DNA.
Active DNA demethylation maintains enhancer activity in nonproliferating cells but can damage DNA.
Topics: DNA Demethylation; Macrophages; Neurons; Enhancer Elements, Genetic; Humans; DNA Breaks, Single-Stranded
PubMed: 36454845
DOI: 10.1126/science.adf3171 -
Nature Communications May 2024Mutations in DNA damage response (DDR) factors are associated with human infertility, which affects up to 15% of the population. The DDR is required during germ cell...
Mutations in DNA damage response (DDR) factors are associated with human infertility, which affects up to 15% of the population. The DDR is required during germ cell development and meiosis. One pathway implicated in human fertility is DNA translesion synthesis (TLS), which allows replication impediments to be bypassed. We find that TLS is essential for pre-meiotic germ cell development in the embryo. Loss of the central TLS component, REV1, significantly inhibits the induction of human PGC-like cells (hPGCLCs). This is recapitulated in mice, where deficiencies in TLS initiation (Rev1 or Pcna) or extension (Rev7 ) result in a > 150-fold reduction in the number of primordial germ cells (PGCs) and complete sterility. In contrast, the absence of TLS does not impact the growth, function, or homeostasis of somatic tissues. Surprisingly, we find a complete failure in both activation of the germ cell transcriptional program and in DNA demethylation, a critical step in germline epigenetic reprogramming. Our findings show that for normal fertility, DNA repair is required not only for meiotic recombination but for progression through the earliest stages of germ cell development in mammals.
Topics: Animals; Humans; DNA Demethylation; Mice; DNA Repair; Germ Cells; DNA-Directed DNA Polymerase; Male; Nucleotidyltransferases; Female; DNA Damage; Mice, Knockout; Meiosis; DNA Replication; Proliferating Cell Nuclear Antigen; Epigenesis, Genetic; Translesion DNA Synthesis
PubMed: 38702312
DOI: 10.1038/s41467-024-47219-2 -
The Plant Cell Mar 2022Cytosine methylation is a reversible epigenetic modification of DNA. In plants, removal of cytosine methylation is accomplished by the four members of the DEMETER (DME)...
Cytosine methylation is a reversible epigenetic modification of DNA. In plants, removal of cytosine methylation is accomplished by the four members of the DEMETER (DME) family of 5-methylcytosine DNA glycosylases, named DME, DEMETER-LIKE2 (DML2), DML3, and REPRESSOR OF SILENCING1 (ROS1) in Arabidopsis thaliana. Demethylation by DME is critical for seed development, preventing experiments to determine the function of the entire gene family in somatic tissues by mutant analysis. Here, we bypassed the reproductive defects of dme mutants to create somatic quadruple homozygous mutants of the entire DME family. dme; ros1; dml2; and dml3 (drdd) leaves exhibit hypermethylated regions compared with wild-type leaves and rdd triple mutants, indicating functional redundancy among all four demethylases. Targets of demethylation include regions co-targeted by RNA-directed DNA methylation and, surprisingly, CG gene body methylation, indicating dynamic methylation at these less-understood sites. Additionally, many tissue-specific methylation differences are absent in drdd, suggesting a role for active demethylation in generating divergent epigenetic states across wild-type tissues. Furthermore, drdd plants display an early flowering phenotype, which involves 5'-hypermethylation and transcriptional down-regulation of FLOWERING LOCUS C. Active DNA demethylation is therefore required for proper methylation across somatic tissues and defines the epigenetic landscape of intergenic and coding regions.
Topics: Arabidopsis Proteins; DNA Demethylation; DNA Methylation; Gene Expression Regulation, Plant; Protein-Tyrosine Kinases; Proto-Oncogene Proteins
PubMed: 34954804
DOI: 10.1093/plcell/koab319