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epigenetic silence

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https://www.readbyqxmd.com/read/28346544/epigenetic-silencing-of-v-d-j-recombination-is-a-major-determinant-for-selective-differentiation-of-mucosal-associated-invariant-t-cells-from-induced-pluripotent-stem-cells
#1
Yutaka Saito, Chie Sugimoto, Toutai Mituyama, Hiroshi Wakao
Mucosal-associated invariant T cells (MAITs) are innate-like T cells that play a pivotal role in the host defense against infectious diseases, and are also implicated in autoimmune diseases, metabolic diseases, and cancer. Recent studies have shown that induced pluripotent stem cells (iPSCs) derived from MAITs selectively redifferentiate into MAITs without altering their antigen specificity. Such a selective differentiation is a prerequisite for the use of MAITs in cell therapy and/or regenerative medicine...
2017: PloS One
https://www.readbyqxmd.com/read/28346436/detailed-comparison-of-retroviral-vectors-and-promoter-configurations-for-stable-and-high-transgene-expression-in-human-induced-pluripotent-stem-cells
#2
D Hoffmann, J W Schott, F K Geis, L Lange, F-J Müller, D Lenz, D Zychlinski, D Steinemann, M Morgan, T Moritz, A Schambach
Correction of patient-specific induced pluripotent stem cells (iPSC) upon gene delivery through retroviral vectors offers new treatment perspectives for monogenetic diseases. Gene-modified iPSC clones can be screened for safe integration sites and differentiated into transplantable cells of interest. However, the current bottleneck is epigenetic vector silencing. In order to identify the most suitable retroviral expression system in iPSC, we systematically compared vectors from different retroviral genera, different promoters and their combination with ubiquitous chromatin opening elements (UCOE), and several envelope pseudotypes...
March 27, 2017: Gene Therapy
https://www.readbyqxmd.com/read/28346433/a-cytosolic-ezh1-isoform-modulates-a-prc2-ezh1-epigenetic-adaptive-response-in-postmitotic-cells
#3
Beatrice Bodega, Federica Marasca, Valeria Ranzani, Alessandro Cherubini, Francesco Della Valle, Maria Victoria Neguembor, Michel Wassef, Alessio Zippo, Chiara Lanzuolo, Massimiliano Pagani, Valerio Orlando
The evolution of chromatin-based epigenetic cell memory may be driven not only by the necessity for cells to stably maintain transcription programs, but also by the need to recognize signals and allow plastic responses to environmental stimuli. The mechanistic role of the epigenome in adult postmitotic tissues, however, remains largely unknown. In vertebrates, two variants of the Polycomb repressive complex (PRC2-Ezh2 and PRC2-Ezh1) control gene silencing via methylation of histone H3 on Lys27 (H3K27me). Here we describe a reversible mechanism that involves a novel isoform of Ezh1 (Ezh1β)...
March 27, 2017: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/28346139/oncometabolite-d-2-hydroxyglutarate-enhances-gene-silencing-through-inhibition-of-specific-h3k36-histone-demethylases
#4
Ryan Janke, Anthony Iavarone, Jasper Rine
Certain mutations affecting central metabolism cause accumulation of the oncometabolite D-2-hydroxyglutarate which promotes progression of certain tumors. High levels of D-2-hydroxyglutarate inhibit the TET family of DNA demethylases and Jumonji family of histone demethylases and cause epigenetic changes that lead to altered gene expression. The link between inhibition of DNA demethylation and changes in expression is strong in some cancers, but not in others. To determine whether D-2-hydroxyglutarate can affect gene expression through inhibiting histone demethylases, orthologous mutations to those known to cause accumulation of D-2-hydroxyglutarate in tumors were generated in Saccharomyces cerevisiae, which has histone demethylases but not DNA methylases or demethylases...
March 27, 2017: ELife
https://www.readbyqxmd.com/read/28345455/recurrent-epigenetic-silencing-of-the-ptprd-tumor-suppressor-in-laryngeal-squamous-cell-carcinoma
#5
Marcin Szaumkessel, Sonia Wojciechowska, Joanna Janiszewska, Natalia Zemke, Ewa Byzia, Katarzyna Kiwerska, Magdalena Kostrzewska-Poczekaj, Adam Ustaszewski, Malgorzata Jarmuz-Szymczak, Reidar Grenman, Malgorzata Wierzbicka, Anna Bartochowska, Krzysztof Szyfter, Maciej Giefing
Cellular processes like differentiation, mitotic cycle, and cell growth are regulated by tyrosine kinases with known oncogenic potential and tyrosine phosphatases that downmodulate the first. Therefore, tyrosine phosphatases are recurrent targets of gene alterations in human carcinomas. We and others suggested recently a tumor suppressor function of the PTPRD tyrosine phosphatase and reported homozygous deletions of the PTPRD locus in laryngeal squamous cell carcinoma. In this study, we investigated other gene-inactivating mechanisms potentially targeting PTPRD, including loss-of-function mutations and also epigenetic alterations like promoter DNA hypermethylation...
March 2017: Tumour Biology: the Journal of the International Society for Oncodevelopmental Biology and Medicine
https://www.readbyqxmd.com/read/28344746/cpg-island-methylator-phenotype-in-adenocarcinomas-from-the-digestive-tract-methods-conclusions-and-controversies
#6
EDITORIAL
Francisco Sánchez-Vega, Valer Gotea, Yun-Ching Chen, Laura Elnitski
Over the last two decades, cancer-related alterations in DNA methylation that regulate transcription have been reported for a variety of tumors of the gastrointestinal tract. Due to its relevance for translational research, great emphasis has been placed on the analysis and molecular characterization of the CpG island methylator phenotype (CIMP), defined as widespread hypermethylation of CpG islands in clinically distinct subsets of cancer patients. Here, we present an overview of previous work in this field and also explore some open questions using cross-platform data for esophageal, gastric, and colorectal adenocarcinomas from The Cancer Genome Atlas...
March 15, 2017: World Journal of Gastrointestinal Oncology
https://www.readbyqxmd.com/read/28343122/genetic-and-epigenetic-variation-of-transposable-elements-in-arabidopsis
#7
REVIEW
Charles J Underwood, Ian R Henderson, Robert A Martienssen
Transposable elements are mobile genetic elements that are prevalent in plant genomes and are silenced by epigenetic modification. Different epigenetic modification pathways play distinct roles in the control of transposable element transcription, replication and recombination. The Arabidopsis genome contains families of all of the major transposable element classes, which are differentially enriched in particular genomic regions. Whole genome sequencing and DNA methylation profiling of hundreds of natural Arabidopsis accessions has revealed that transposable elements exhibit significant intraspecific genetic and epigenetic variation, and that genetic variation often underlies epigenetic variation...
March 23, 2017: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/28343076/repression-of-dok7-mediated-by-dnmt3a-promotes-the-proliferation-and-invasion-of-kyse410-and-te-12-escc-cells
#8
Shou-Mei Yang, Su-Yi Li, Hao-Bin Yu, Jie-Ru Li, Lei-Lei Sun
Increasing evidence shows that aberrant epigenetic regulation of tumor suppressor genes is a contributing factor to their altered expression in esophageal squamous cell carcinoma (ESCC). In the current study, we investigate the role of DOK7 in ESCC cells. We found that enforced expression of DOK7 inhibited the proliferation and invasion of ESCC cells. We also found that treatment of ESCC cells with the DNA methylation inhibitor, 5-aza-2-deoxycytidine (5-azadC), induced the demethylation of DOK7 in promoter and DOK7 expression...
March 23, 2017: Biomedicine & Pharmacotherapy, Biomédecine & Pharmacothérapie
https://www.readbyqxmd.com/read/28342717/slow-chromatin-dynamics-allow-polycomb-target-genes-to-filter-fluctuations-in-transcription-factor-activity
#9
Scott Berry, Caroline Dean, Martin Howard
Genes targeted by Polycomb repressive complex 2 (PRC2) are regulated in cis by chromatin modifications and also in trans by diffusible regulators such as transcription factors. Here, we introduce a mathematical model in which transcription directly antagonizes Polycomb silencing, thereby linking these cis- and trans-regulatory inputs to gene expression. The model is parameterized by recent experimental data showing that PRC2-mediated repressive chromatin modifications accumulate extremely slowly. The model generates self-perpetuating, bistable active and repressed chromatin states that persist through DNA replication, thereby ensuring high-fidelity transmission of the current chromatin state...
March 21, 2017: Cell Systems
https://www.readbyqxmd.com/read/28342451/tert-promoter-mutations-in-telomere-biology
#10
REVIEW
Barbara Heidenreich, Rajiv Kumar
Telomere repeats at chromosomal ends, critical to genome integrity, are maintained through an elaborate network of proteins and pathways. Shelterin complex proteins shield telomeres from induction of DNA damage response to overcome end protection problem. A specialized ribonucleic protein, telomerase, maintains telomere homeostasis through repeat addition to counter intrinsic shortcomings of DNA replication that leads to gradual sequence shortening in successive mitoses. The biogenesis and recruitment of telomerase composed of telomerase reverse transcriptase (TERT) subunit and an RNA component, takes place through the intricate machinery that involves an elaborate number of molecules...
January 2017: Mutation Research
https://www.readbyqxmd.com/read/28340355/the-human-immunodeficiency-virus-1-asp-rna-promotes-viral-latency-by-recruiting-the-polycomb-repressor-complex-2-and-promoting-nucleosome-assembly
#11
Juan C Zapata, Federica Campilongo, Robert A Barclay, Catherine DeMarino, Maria D Iglesias-Ussel, Fatah Kashanchi, Fabio Romerio
Various epigenetic marks at the HIV-1 5'LTR suppress proviral expression and promote latency. Cellular antisense transcripts known as long noncoding RNAs (lncRNAs) recruit the polycomb repressor complex 2 (PRC2) to gene promoters, which catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3), thus promoting nucleosome assembly and suppressing gene expression. We found that an HIV-1 antisense transcript expressed from the 3'LTR and encoding the antisense protein ASP promotes proviral latency. Expression of ASP RNA reduced HIV-1 replication in Jurkat cells...
March 21, 2017: Virology
https://www.readbyqxmd.com/read/28338971/progressive-silencing-of-the-zinc-transporter-zip8-slc39a8-in-chronic-cadmium-exposed-lung-epithelial-cells
#12
Yangmin Gao, Yanming Xu, Dandan Wu, Feiyuan Yu, Lei Yang, Yue Yao, Zhanling Liang, Andy T Y Lau
Cadmium (Cd), a non-essential metal, stealthily enters the cells by utilizing the essential metal importing pathways. The zinc transporters Zip8, Zip14, and divalent metal transporter 1 (Dmt1) are now emerging as several important metal transporters involved in cellular Cd incorporation and their expressions have been shown to be down-regulated in several Cd-resistant (CdR) cell lines, however, the involvement of these transporters during the development of Cd-resistance in lung cells is unclear. In this study, we therefore check the expression of these metal transporters in our previously established rat lung epithelial cells (LECs) and show that the level of Zip8 is progressively silenced when LECs are adapted to increasing concentrations of CdCl2 (from 1 to 20 μM)...
March 18, 2017: Acta Biochimica et Biophysica Sinica
https://www.readbyqxmd.com/read/28338097/the-cellular-protein-hnrnp-a2-b1-enhances-hiv-1-transcription-by-unfolding-ltr-promoter-g-quadruplexes
#13
Matteo Scalabrin, Ilaria Frasson, Emanuela Ruggiero, Rosalba Perrone, Elena Tosoni, Sara Lago, Martina Tassinari, Giorgio Palù, Sara N Richter
G-quadruplexes are four-stranded conformations of nucleic acids that act as cellular epigenetic regulators. A dynamic G-quadruplex forming region in the HIV-1 LTR promoter represses HIV-1 transcription when in the folded conformation. This activity is enhanced by nucleolin, which induces and stabilizes the HIV-1 LTR G-quadruplexes. In this work by a combined pull-down/mass spectrometry approach, we consistently found hnRNP A2/B1 as an additional LTR-G-quadruplex interacting protein. Surface plasmon resonance confirmed G-quadruplex specificity over linear sequences and fluorescence resonance energy transfer analysis indicated that hnRNP A2/B1 is able to efficiently unfold the LTR G-quadruplexes...
March 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28334816/dynamic-changes-in-chromatin-states-during-specification-and-differentiation-of-adult-intestinal-stem-cells
#14
Juri Kazakevych, Sergi Sayols, Berith Messner, Christina Krienke, Natalia Soshnikova
Epigenetic mechanisms, including chromatin structure, chromatin dynamics and histone modifications play an important role for maintenance and differentiation of pluripotent embryonic stem cells. However, little is known about the molecular mechanisms of adult stem cell specification and differentiation. Here, we used intestinal stem cells (ISCs) as a model system to reveal the epigenetic changes coordinating gene expression programs during these processes. We found that two distinct epigenetic mechanisms participate in establishing the transcriptional program promoting ISC specification from embryonic progenitors...
March 7, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334277/in-bone-metastasis-mir-34a-5p-absence-inversely-correlates-with-met-expression-while-met-oncogene-is-unaffected-by-mir-34a-5p-in-non-metastatic-and-metastatic-breast-carcinomas
#15
Paola Maroni, Rossella Puglisi, Gianfranco Mattia, Alessandra Carè, Emanuela Matteucci, Paola Bendinelli, Maria Alfonsina Desiderio
The highlight of the molecular basis and therapeutic targets of the bone-metastatic process requires the identification of biomarkers of metastasis colonization. Here, we studied miR-34a-5p expression, and Met-receptor expression and localization in bone metastases from ductal breast carcinomas, and in ductal carcinomas without history of metastasis (20 cases). miR-34a-5p was elevated in non-metastatic breast carcinoma, intermediate in the adjacent tissue and practically absent in bone metastases, opposite to pair-matched carcinoma...
March 16, 2017: Carcinogenesis
https://www.readbyqxmd.com/read/28326594/hypoacetylation-of-acetyl-histone-h3-h3k9ac-as-marker-of-poor-prognosis-in-oral-cancer
#16
Liana Preto Webber, Vivian Petersen Wagner, Marina Curra, Pablo Agustin Vargas, Luise Meurer, Vinícius Coelho Carrard, Cristiane Helena Squarize, Rogério Moraes Castilho, Manoela Domingues Martins
AIMS: Epigenetics refers to changes in cell characteristics that occur independently of modifications to the DNA sequence. Oral carcinogenesis is influenced by modifications in epigenetic mechanisms, including changes in histones, which are proteins that support chromatin remodeling for the dynamic regulation of gene expression and silencing. The dysregulation of histone acetylation can lead to the uncontrolled activity of different genes, thereby triggering events associated with malignant transformation...
March 22, 2017: Histopathology
https://www.readbyqxmd.com/read/28320934/allele-specific-non-cg-dna-methylation-marks-domains-of-active-chromatin-in-female-mouse-brain
#17
Christopher L Keown, Joel B Berletch, Rosa Castanon, Joseph R Nery, Christine M Disteche, Joseph R Ecker, Eran A Mukamel
DNA methylation at gene promoters in a CG context is associated with transcriptional repression, including at genes silenced on the inactive X chromosome in females. Non-CG methylation (mCH) is a distinct feature of the neuronal epigenome that is differentially distributed between males and females on the X chromosome. However, little is known about differences in mCH on the active (Xa) and inactive (Xi) X chromosomes because stochastic X-chromosome inactivation (XCI) confounds allele-specific epigenomic profiling...
March 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28319413/aberrant-promoter-hypermethylation-of-p16-survivin-and-retinoblastoma-in-gastric-cancer
#18
L Guo, C Huang, Q J Ji
BACKGROUND: Gastric cancer is common and can be found throughout the world. Notoriously like other cancers, gastric cancer is a consequence of cellular regulation disorder. Epigenetics, including many oncogenes or tumour suppressor genes, can provide some clues for this kind of disorder. DNA methylation, especially promoter methylation, which causes the silence/decrease of tumour related genes, has become a focus in various tumour types. The aim of this study was to investigate promoter methylation of certain genes: p16, survivin, retinoblastoma (Rb), all of which have been regarded as genes related to gastric cancer...
2017: Bratislavské Lekárske Listy
https://www.readbyqxmd.com/read/28318821/snf2-family-protein-fft3-suppresses-nucleosome-turnover-to-promote-epigenetic-inheritance-and-proper-replication
#19
Nitika Taneja, Martin Zofall, Vanivilasini Balachandran, Gobi Thillainadesan, Tomoyasu Sugiyama, David Wheeler, Ming Zhou, Shiv I S Grewal
Heterochromatin can be epigenetically inherited in cis, leading to stable gene silencing. However, the mechanisms underlying heterochromatin inheritance remain unclear. Here, we identify Fft3, a fission yeast homolog of the mammalian SMARCAD1 SNF2 chromatin remodeler, as a factor uniquely required for heterochromatin inheritance, rather than for de novo assembly. Importantly, we find that Fft3 suppresses turnover of histones at heterochromatic loci to facilitate epigenetic transmission of heterochromatin in cycling cells...
March 8, 2017: Molecular Cell
https://www.readbyqxmd.com/read/28315733/wt1-ameliorates-podocyte-injury-via-repression-of-ezh2-%C3%AE-catenin-pathway-in-diabetic-nephropathy
#20
Jiao Wan, Xiaoyan Hou, Zhanmei Zhou, Jian Geng, Jianwei Tian, Jing Nie, Xiaoyan Bai
Epigenetic modulation of podocyte injury plays a pivotal role in diabetic nephropathy (DN). Wilm's tumor 1 (WT1) has been found to have opposing roles with β-catenin in podocyte biology. Herein, we asked whether the histone methyltransferase enzyme enhancer of zeste homolog 2 (EZH2) promotes WT1-induced podocyte injury via β-catenin activation and the underlying mechanisms. We found that WT1 antagonized EZH2 and ameliorated β-catenin-mediated podocyte injury as demonstrated by attenuated podocyte mesenchymal transition, maintenance of podocyte architectural integrity, decreased podocyte apoptosis and oxidative stress...
March 15, 2017: Free Radical Biology & Medicine
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