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Evaluation of Water and Its Contaminants
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 5, 2017
William J. Rea, Kalpana D. Patel
DNA methylation is tightly regulated in mammalian development and is essential for maintaining the normal functioning of the adult organism.258 Altered DNA methylation has been associated with several human diseases.259 Global genomic DNA hypomethylation is a hallmark of many types of cancers,260 resulting in illegitimate recombination events and causing transcriptional deregulation of affected genes.259 In mammalian systems, DNA methylation occurs predominantly in cytosine-rich gene regions, known as CpG islands, and serves to regulate gene expression and maintain genome stability.261 DNA methyltransferases (DNMTs) are responsible for transferring a methyl group from the S-adenosyl methionine (SAM) cofactor to the cytosine nucleotide, producing 5′-methylcytosine and S-adenosyl homocysteine (Figure 3.14).262 Three different families of DNMT genes have been identified so far: DNMT1, DNMT2, and DNMT3.263
Role of Histone Methyltransferase in Breast Cancer
Published in Meenu Gupta, Rachna Jain, Arun Solanki, Fadi Al-Turjman, Cancer Prediction for Industrial IoT 4.0: A Machine Learning Perspective, 2021
Surekha Manhas, Zaved Ahmed Khan
Methylation of DNA occurs through the activity of the target enzyme DNA methyltransferases (DNMTs). Solid circles (cytosine residues mostly are methylated) are bounded by histone-modifying enzymes, which subsequently recruit histone methyltransferases and histone deacetylases (HDACs). In addition, these enzymes are responsible for the induction of complex variable changes in the pattern of histone modification, which result in repressive chromatin structure establishment. Open circles = unmethylated cytosine residues; acH4K12 < lysine 12-H4 acetylene histone; mH3K9 = lysine 9–methylated histone H3; acH4K5 = lysine 5–acetylated histone H4 and mono, di, tri = all-methylated [2].
Epigenetic Landscape–Modifying Nanoparticles
Published in Pradipta Ranjan Rauta, Yugal Kishore Mohanta, Debasis Nayak, Nanotechnology in Biology and Medicine, 2019
DNA methylation in mammalian systems is done by catalytic activity of DNA methyltransferase (DNMT) enzymes. The DNMT family in mammalian system consists of five DNMT enzymes, which are DNMT1, DNMT2, DNMT3a, DNMT3b, and DNMT3L. Current studies show that among these DNMT1, DNMT3a, and DNMT3b have methyltransferase activity.
Organism-derived phthalate derivatives as bioactive natural products
Published in Journal of Environmental Science and Health, Part C, 2018
Huawei Zhang, Yi Hua, Jianwei Chen, Xiuting Li, Xuelian Bai, Hong Wang
DNA methylation is catalyzed by DNA methyltransferases (DNMTs) including DNMT1, DNMT2, DNMT3A, DNMT3b and DNMT31 in mammalian cells. Diethyl phthalate (DEP) was shown to be a potential endocrine disruptor due to increasing the DNMT3a, DNMT3b and SIRT1.[51] Olive flounder Paralichthys olivaceus was treated with DEP at 100–900 mg/kg induced oxidative stress and activated compensatory anti-oxidant systems.[52] The exposure of DEP to zebrafish embryos in early developmental stages influenced the transcription levels of innate immune-related gene and the induction of antioxidant enzyme activities,[53] human macrophages and dermal cells via modification of lipoproteins and production of dysfunctional HDL were also affected severely,[54] and DEP brings about significant changes in the activity of certain liver and muscle enzymes such as a significant increase in liver and muscle ACP and ALP,[55] carp was exposed to DEP showed the compound acts on carp liver superoxide dismutase, catalase and glutathione peroxidase (GPH-PX) activities and the abilities of carp anti-anion and anti-superoxide hydroxyl radicals.[56]
Epigenotoxicity: a danger to the future life
Published in Journal of Environmental Science and Health, Part A, 2023
Farzaneh Kefayati, Atoosa Karimi Babaahmadi, Taraneh Mousavi, Mahshid Hodjat, Mohammad Abdollahi
DNA methyltransferases (DNMTs) are a group of enzymes that transmit a methyl group to the C-5 position of DNA cytosines from their cofactor s-adenosylmethionine via specific reactions. They are classified according to their function into two groups of maintenance enzymes and de novo. De novo DNMTs put methyl groups in places that already lack methyl, while maintenance of DNMTs adds methyl to hemi methyl moieties.[9] DNA methylation also occurs during cell division and is transferred to daughter cells along with the DNA sequence. DNMT1 is responsible for replicating the methylation pattern from the parent to the daughter string. As a maintenance methyltransferase, this enzyme is associated with hemimethylated DNA, showing signs of methylation in only one strand. DNMT1 also binds to hemimethylated DNA and helps methylate the daughter strand to recover fully methylated CpG dinucleotides. Thus, DNMT1 maintains the stability of this epigenetic mark across different generations. Methylated CPGs may bind to methyl-CPG proteins associated with methyl CpG binding proteins 1 and 2 (MECP1 and MECP2 (MBDs)), which can alter transcription. Methylated DNA harbors additional proteins known as methyl-CpG binding domain proteins, which interact with other proteins such as histone deacetylase (HDAC) and thus create compressed and inactive chromatin.[11] DNA methylation by DNA de novo 3 A (DNMT3A) and 3B (DNMT3B) methyltransferases is essential for genome regulation. Irregularities in the activity of these enzymes cause various diseases, especially cancer. DNMT3A is significant for establishing patterns for DNA methylation during development before birth.[12]
Benzo[a]pyrene osteotoxicity and the regulatory roles of genetic and epigenetic factors: A review
Published in Critical Reviews in Environmental Science and Technology, 2022
Jiezhang Mo, Doris Wai-Ting Au, Jiahua Guo, Christoph Winkler, Richard Yuen-Chong Kong, Frauke Seemann
DNA methylation, closely associated with transcriptional silencing, presents at the 5′ position of the cytosine ring within CpG dinucleotides of DNA. It is catalyzed by DNA methyltransferases (DNMTs) that include DNMT1, DNMT3A and DNMT3B (Chen & Zhang, 2020). Passive demethylation occurs via the suppression of DNA methylation maintenance during DNA replication, while active DNA demethylation is achieved by a methylcytosine-to-hydroxymethylcytosine conversion and a follow-up base excision repair, catalyzed by the ten eleven translocation (TET) gene family members (Guo et al., 2011).