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DNA demethylation

Haniyeh Eyvani, Farima Moghaddaskho, Majid Kabuli, Ali Zekri, Majid Momeny, Javad Tavakkoly-Bazzaz, Kamran Alimoghaddam, Ardeshir Ghavamzadeh, Seyed H Ghaffari
AIMS: Cell cycle dysregulation is important in tumorigenesis. Transcriptional silencing of cell cycle regulatory genes, due to DNA methylation, is a common epigenetic event in malignancies. As2O3 has been shown to induce cell cycle arrest and also to be a potential hypomethylating agent. Our study aimed to investigate DNA methylation patterns of cell cycle regulatory genes promoters, the effects of Arsenic trioxide (As2O3) on the methylated genes and cell cycle distribution in colorectal cancer (CRC) cell lines...
October 18, 2016: Life Sciences
Gosuke Hayashi, Kenta Koyama, Hidefumi Shiota, Asuka Kamio, Takayoshi Umeda, Genta Nagae, Hiroyuki Aburatani, Akimitsu Okamoto
5-hydroxymethylcytosine (hmC) is an essential intermediate in the active DNA demethylation pathway. Here we report a new base-resolution method for measuring hmC by combining peroxotungstate-mediated oxidation and sequencing analysis. We reveal that an oxidized product of hmC, trihydroxylated thymine (thT), tolerated the incorporation of dATP as a substrate in the process of DNA polymerase elongation. By comparing the results of Sanger sequencing before and after the oxidation, we observed that hmC sites on single-stranded DNAs could be discriminated from unmethylated cytosines...
October 21, 2016: Journal of the American Chemical Society
Jing Chen, Xiaoyan Zhang, Han Zhang, Tongqiang Liu, Hui Zhang, Jie Teng, Jun Ji, Xiaoqiang Ding
Chronic kidney disease (CKD) is a state of Klotho deficiency. The Klotho expression may be suppressed due to DNA hypermethylation in cancer cells so we have investigated the effects and possible mechanisms by which Klotho expression is regulated in human aortic smooth muscle cells (HASMCs). The vascular Klotho hypermethylation in radial arteries of patients with end-stage renal disease was described. Cultured HASMCs and 5/6-nephrectomized Sprague Dawley (SD) rats treated with indoxyl sulfate (IS) were used as in vitro and in vivo models, respectively...
2016: International Journal of Biological Sciences
Yan Long, Wen-Bin Tsai, Jeffrey T Chang, Marcos Estecio, Medhi Wangpaichitr, Naramol Savaraj, Lynn G Feun, Helen H W Chen, Macus Tien Kuo
Many human tumors require extracellular arginine (Arg) for growth because the key enzyme for de novo biosynthesis of Arg, argininosuccinate synthetase 1 (ASS1), is silenced. These tumors are sensitive to Arg-starvation therapy using pegylated arginine deiminase (ADI-PEG20) which digests extracellular Arg. Many previous studies reported that ASS1 silencing is due to epigenetic inactivation of ASS1 expression by DNA methylation, and that the demethylation agent 5-aza-deoxycytidine (Aza-dC) can induce ASS1 expression...
September 28, 2016: Oncotarget
Tushar Tomar, Steven de Jong, Nicolette G Alkema, Rieks L Hoekman, Gert Jan Meersma, Harry G Klip, Ate Gj van der Zee, G Bea A Wisman
BACKGROUND: In high-grade serous ovarian cancer (HGSOC), intrinsic and/or acquired resistance against platinum-containing chemotherapy is a major obstacle for successful treatment. A low frequency of somatic mutations but frequent epigenetic alterations, including DNA methylation in HGSOC tumors, presents the cancer epigenome as a relevant target for innovative therapy. Patient-derived xenografts (PDXs) supposedly are good preclinical models for identifying novel drug targets. However, the representativeness of global methylation status of HGSOC PDXs compared to their original tumors has not been evaluated so far...
October 20, 2016: Genome Medicine
Hai-Qiang Dai, Bang-An Wang, Lu Yang, Jia-Jia Chen, Guo-Chun Zhu, Mei-Ling Sun, Hao Ge, Rui Wang, Deborah L Chapman, Fuchou Tang, Xin Sun, Guo-Liang Xu
Mammalian genomes undergo epigenetic modifications, including cytosine methylation by DNA methyltransferases (DNMTs). Oxidation of 5-methylcytosine by the Ten-eleven translocation (TET) family of dioxygenases can lead to demethylation. Although cytosine methylation has key roles in several processes such as genomic imprinting and X-chromosome inactivation, the functional significance of cytosine methylation and demethylation in mouse embryogenesis remains to be fully determined. Here we show that inactivation of all three Tet genes in mice leads to gastrulation phenotypes, including primitive streak patterning defects in association with impaired maturation of axial mesoderm and failed specification of paraxial mesoderm, mimicking phenotypes in embryos with gain-of-function Nodal signalling...
October 19, 2016: Nature
Anne Rochtus, Raf Winand, Griet Laenen, Elise Vangeel, Benedetta Izzi, Christine Wittevrongel, Yves Moreau, Carla Verpoorten, Katrien Jansen, Chris Van Geet, Kathleen Freson
BACKGROUND: Neural tube defects (NTDs) are severe congenital malformations that arise from failure of neurulation during early embryonic development. The molecular basis underlying most human NTDs still remains largely unknown. Based on the hypothesis that folic acid prevents NTDs by stimulating methylation reactions, DNA methylation changes could play a role in NTDs. We performed a methylome analysis for patients with myelomeningocele (MMC). Using a candidate CpG analysis for HOX genes, a significant association between HOXB7 hypomethylation and MMC was found...
2016: Clinical Epigenetics
Federica Parodi, Roberta Carosio, Marco Ragusa, Cinzia Di Pietro, Marco Maugeri, Davide Barbagallo, Fabio Sallustio, Giorgio Allemanni, Maria Pia Pistillo, Ida Casciano, Alessandra Forlani, Francesco P Schena, Michele Purrello, Massimo Romani, Barbara Banelli
In neuroblastoma, the epigenetic landscape is more profoundly altered in aggressive compared to lower grade tumors and the concomitant hypermethylation of many genes, defined as "methylator phenotype", has been associated with poor outcome. DNA methylation can interfere with gene expression acting at distance through the methylation or demethylation of the regulatory regions of miRNAs. The multiplicity of miRNA targets may result in the simultaneous alteration of many biological pathways like cell proliferation, apoptosis, migration and differentiation...
October 15, 2016: Biochimica et Biophysica Acta
Ornella Affinito, Giovanni Scala, Domenico Palumbo, Ermanno Florio, Antonella Monticelli, Gennaro Miele, Vittorio Enrico Avvedimento, Alessandro Usiello, Lorenzo Chiariotti, Sergio Cocozza
DNA methylation is often analyzed by reporting the average methylation degree of each cytosine. In this study, we used a single molecule methylation analysis in order to look at the methylation conformation of individual molecules. Using D-aspartate oxidase as a model gene, we performed an in-depth methylation analysis through the developmental stages of three different mouse tissues (brain, lung, and gut), where this gene undergoes opposite methylation destiny. This approach allowed us to track both methylation and demethylation processes at high resolution...
October 17, 2016: Epigenetics: Official Journal of the DNA Methylation Society
Xin Li, Yun Liu, Tal Salz, Kasper D Hansen, Andrew P Feinberg
DNA methylation at the 5-postion of cytosine (5mC) is an epigenetic modification that regulates gene expression and cellular plasticity in development and disease. The ten-eleven translocation (TET) gene family oxidizes 5mC to 5-hydroxymethylcytosine (5hmC), providing an active mechanism for DNA demethylation, and may also provide its own regulatory function. Here we applied oxidative bisulfite sequencing to generate whole-genome DNA methylation and hydroxymethylation maps at single-base resolution in paired human liver and lung normal and cancer...
October 13, 2016: Genome Research
Nathalie Dehne, Bernhard Brüne
Hypoxia, by activating transcription factors induces transcription of some genes but it also reduces mRNA synthesis by mechanisms that are poorly defined. Activation of human macrophages with interleukin (IL)-4 showed that up-regulation of some IL-4 target genes was reduced when macrophages were incubated at 1% oxygen. Hypoxia impaired induction of chemokine (C-C motif) ligand 18 (CCL18), although IL-4-induced DNA binding of the transcription factor STAT6 remained intact. In contrast, induction of serine peptidase inhibitor, Kunitz type (SPINT)2, another IL-4/STAT6 target gene, was not affected by hypoxia...
October 11, 2016: Biochimica et Biophysica Acta
Jianing Zhong, Xianfeng Li, Wanshi Cai, Yan Wang, Shanshan Dong, Jie Yang, Jian'an Zhang, Nana Wu, Yuanyuan Li, Fengbiao Mao, Cheng Zeng, Jinyu Wu, Xingzhi Xu, Zhong Sheng Sun
The Ten Eleven Translocation 1 (TET1) protein is a DNA demethylase that regulates gene expression through altering statue of DNA methylation. However, recent studies have demonstrated that TET1 could modulate transcriptional expression independent of its DNA demethylation activity; yet, the detailed mechanisms underlying TET1's role in such transcriptional regulation remain not well understood. Here, we uncovered that Tet1 formed a chromatin complex with histone acetyltransferase Mof and scaffold protein Sin3a in mouse embryonic stem cells by integrative genomic analysis using publicly available ChIP-seq data sets and a series of in vitro biochemical studies in human cell lines...
October 12, 2016: Nucleic Acids Research
Moshe Szyf
5'-hydroxymethylcytosine (5hmC) is a variant of the common covalent epigenetic modification of DNA 5'-methylcytosine (5mC). Although the presence of this modified base in mammalian DNA has been recognized for several decades, it has recently gained center stage as a suspected intermediate in enzymatic active demethylation of 5mC. The role of 5hmC remains elusive in spite of a large body of studies. It is proposed that 5hmC is a variant of the 5mC epigenetic signal and is involved in epigenetic regulation of gene function...
October 13, 2016: Epigenomics
Nidal E Muvarak, Khadiza Chowdhury, Limin Xia, Carine Robert, Eun Yong Choi, Yi Cai, Marina Bellani, Ying Zou, Zeba N Singh, Vu H Duong, Tyler Rutherford, Pratik Nagaria, Søren M Bentzen, Michael M Seidman, Maria R Baer, Rena G Lapidus, Stephen B Baylin, Feyruz V Rassool
Poly (ADP-ribose) polymerase inhibitors (PARPis) are clinically effective predominantly for BRCA-mutant tumors. We introduce a mechanism-based strategy to enhance PARPi efficacy based on DNA damage-related binding between DNA methyltransferases (DNMTs) and PARP1. In acute myeloid leukemia (AML) and breast cancer cells, DNMT inhibitors (DNMTis) alone covalently bind DNMTs into DNA and increase PARP1 tightly bound into chromatin. Low doses of DNMTis plus PARPis, versus each drug alone, increase PARPi efficacy, increasing amplitude and retention of PARP1 directly at laser-induced DNA damage sites...
October 10, 2016: Cancer Cell
Ferdinand von Meyenn, Rebecca V Berrens, Simon Andrews, Fátima Santos, Amanda J Collier, Felix Krueger, Rodrigo Osorno, Wendy Dean, Peter J Rugg-Gunn, Wolf Reik
Primordial germ cell (PGC) development is characterized by global epigenetic remodeling, which resets genomic potential and establishes an epigenetic ground state. Here we recapitulate PGC specification in vitro from naive embryonic stem cells and characterize the early events of epigenetic reprogramming during the formation of the human and mouse germline. Following rapid de novo DNA methylation during priming to epiblast-like cells, methylation is globally erased in PGC-like cells. Repressive chromatin marks (H3K9me2/3) and transposable elements are enriched at demethylation-resistant regions, while active chromatin marks (H3K4me3 or H3K27ac) are more prominent at regions that demethylate faster...
October 10, 2016: Developmental Cell
B C Medeiros, A T Fathi, C D DiNardo, D A Pollyea, S M Chan, R Swords
Alterations to genes involved in cellular metabolism and epigenetic regulation are implicated in the pathogenesis of myeloid malignancies. Recurring mutations in isocitrate dehydrogenase (IDH) genes are detected in approximately 20% of adult patients with acute myeloid leukemia (AML) and 5% of adults with myelodysplastic syndromes (MDS). IDH proteins are homodimeric enzymes involved in diverse cellular processes, including adaptation to hypoxia, histone demethylation, and DNA modification. The IDH2 protein is localized in the mitochondria and is a critical component of the tricarboxylic acid (TCA, also called the 'citric acid' or Krebs) cycle...
October 10, 2016: Leukemia: Official Journal of the Leukemia Society of America, Leukemia Research Fund, U.K
Miho M Suzuki, Tomoko Mori, Noriyuki Satoh
The initiation of embryonic gene expression in ascidian embryos appears to be tightly regulated by the number of DNA replication cycles. DNA methylation is thought to contribute to the clock mechanism that counts the rounds of DNA replication. We used mass spectrometry and whole genome bisulfite sequencing to characterize DNA methylation changes that occur in early developmental stages of the ascidian, Ciona intestinalis. We found that global DNA methylation in early Ciona development was static, and a base-wise comparison between the genomes of consecutive developmental stages found no DNA demethylation that was related to zygotic gene activation...
October 5, 2016: Genomics
Masahiro Maeda, Hiroshi Moro, Toshikazu Ushijima
Multiple pathogenic mechanisms by which Helicobacter pylori infection induces gastric cancer have been established in the last two decades. In particular, aberrant DNA methylation is induced in multiple driver genes, which inactivates them. Methylation profiles in gastric cancer are associated with specific subtypes, such as microsatellite instability. Recent comprehensive and integrated analyses showed that many cancer-related pathways are more frequently altered by aberrant DNA methylation than by mutations...
October 7, 2016: Gastric Cancer
Valentina Damiano, Giulia Brisotto, Silvia Borgna, Alessandra di Gennaro, Michela Armellin, Tiziana Perin, Michela Guardascione, Roberta Maestro, Manuela Santarosa
Loss of expression of miR-200 family members has been implicated in cellular plasticity, a phenomenon that accounts for epithelial-to-mesenchymal transition (EMT) and stem-like features of many carcinomas and is considered a major cause of tumor aggressiveness and drug resistance. Nevertheless, the mechanisms of miR-200 downregulation in breast cancer are still largely unknown. Here we show that miR-200c expression inversely correlates with miR-200c/miR-141 locus methylation in triple-negative breast tumors (TNBC)...
September 22, 2016: Genes, Chromosomes & Cancer
Hesbon Z Amenya, Chiharu Tohyama, Seiichiroh Ohsako
The aryl hydrocarbon receptor (Ahr) is a highly conserved nuclear receptor that plays an important role in the manifestation of toxicity induced by polycyclic aromatic hydrocarbons. As a xenobiotic sensor, Ahr is involved in chemical biotransformation through activation of drug metabolizing enzymes. The activated Ahr cooperates with coactivator complexes to induce epigenetic modifications at target genes. Thus, it is conceivable that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a potent Ahr ligand, may elicit robust epigenetic changes in vivo at the Ahr target gene cytochrome P450 1a1 (Cyp1a1)...
October 7, 2016: Scientific Reports
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