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https://www.readbyqxmd.com/read/28092686/epigenomic-reprogramming-during-pancreatic-cancer-progression-links-anabolic-glucose-metabolism-to-distant-metastasis
#1
Oliver G McDonald, Xin Li, Tyler Saunders, Rakel Tryggvadottir, Samantha J Mentch, Marc O Warmoes, Anna E Word, Alessandro Carrer, Tal H Salz, Sonoko Natsume, Kimberly M Stauffer, Alvin Makohon-Moore, Yi Zhong, Hao Wu, Kathryn E Wellen, Jason W Locasale, Christine A Iacobuzio-Donahue, Andrew P Feinberg
During the progression of pancreatic ductal adenocarcinoma (PDAC), heterogeneous subclonal populations emerge that drive primary tumor growth, regional spread, distant metastasis, and patient death. However, the genetics of metastases largely reflects that of the primary tumor in untreated patients, and PDAC driver mutations are shared by all subclones. This raises the possibility that an epigenetic process might operate during metastasis. Here we report large-scale reprogramming of chromatin modifications during the natural evolution of distant metastasis...
January 16, 2017: Nature Genetics
https://www.readbyqxmd.com/read/28091870/perspectives-using-polymer-modeling-to-understand-the-formation-and-function-of-nuclear-compartments
#2
REVIEW
N Haddad, D Jost, C Vaillant
Compartmentalization is a ubiquitous feature of cellular function. In the nucleus, early observations revealed a non-random spatial organization of the genome with a large-scale segregation between transcriptionally active-euchromatin-and silenced-heterochromatin-parts of the genome. Recent advances in genome-wide mapping and imaging techniques have strikingly improved the resolution at which nuclear genome folding can be analyzed and have revealed a multiscale spatial compartmentalization with increasing evidences that such compartment may indeed result from and participate to genome function...
January 14, 2017: Chromosome Research
https://www.readbyqxmd.com/read/28091603/repo-man-pp1-regulates-heterochromatin-formation-in-interphase
#3
Inês J de Castro, James Budzak, Maria L Di Giacinto, Lorena Ligammari, Ezgi Gokhan, Christos Spanos, Daniela Moralli, Christine Richardson, Jose I de Las Heras, Silvia Salatino, Eric C Schirmer, Katharine S Ullman, Wendy A Bickmore, Catherine Green, Juri Rappsilber, Sarah Lamble, Martin W Goldberg, Veronica Vinciotti, Paola Vagnarelli
Repo-Man is a protein phosphatase 1 (PP1) targeting subunit that regulates mitotic progression and chromatin remodelling. After mitosis, Repo-Man/PP1 remains associated with chromatin but its function in interphase is not known. Here we show that Repo-Man, via Nup153, is enriched on condensed chromatin at the nuclear periphery and at the edge of the nucleopore basket. Repo-Man/PP1 regulates the formation of heterochromatin, dephosphorylates H3S28 and it is necessary and sufficient for heterochromatin protein 1 binding and H3K27me3 recruitment...
January 16, 2017: Nature Communications
https://www.readbyqxmd.com/read/28088028/role-of-small-rnas-in-epigenetic-reprogramming-during-plant-sexual-reproduction
#4
REVIEW
German Martinez, Claudia Köhler
Sexual reproduction, the formation of a new individual from specialized reproductive cells after fertilization, involves the precise orchestration of different developmental and genomic processes. These processes are to a large extent governed by small RNAs (sRNAs) that either belong to the class of micro RNAs (miRNAs) or small-interfering RNAs (siRNAs). The latter are derived from transposable elements (TEs) and involved in genome defense and transgenerational inheritance of heterochromatin identity, ensuring genome stability...
January 11, 2017: Current Opinion in Plant Biology
https://www.readbyqxmd.com/read/28087716/the-piggybac-transposon-derived-genes-tpb1-and-tpb6-mediate-essential-transposon-like-excision-during-the-developmental-rearrangement-of-key-genes-in-tetrahymena-thermophila
#5
Chao-Yin Cheng, Janet M Young, Chih-Yi Gabriela Lin, Ju-Lan Chao, Harmit S Malik, Meng-Chao Yao
Ciliated protozoans perform extreme forms of programmed somatic DNA rearrangement during development. The model ciliate Tetrahymena thermophila removes 34% of its germline micronuclear genome from somatic macronuclei by excising thousands of internal eliminated sequences (IESs), a process that shares features with transposon excision. Indeed, piggyBac transposon-derived genes are necessary for genome-wide IES excision in both Tetrahymena (TPB2 [Tetrahymena piggyBac-like 2] and LIA5) and Paramecium tetraurelia (PiggyMac)...
December 15, 2016: Genes & Development
https://www.readbyqxmd.com/read/28081279/karyotype-analysis-and-ribosomal-gene-localization-of-spotted-knifejaw-oplegnathus-punctatus
#6
P Z Li, D D Cao, X B Liu, Y J Wang, H Y Yu, X J Li, Q Q Zhang, X B Wang
The spotted knifejaw, Oplegnathus punctatus, is an important aquaculture fish species in China. To better understand the chromosomal microstructure and the karyotypic origin of this species, cytogenetic analysis was performed using Giemsa staining to identify metaphase chromosomes, C-banding to detect C-positive heterochromatin, silver staining to identify the nucleolus organizer regions (Ag-NORs), and fluorescence in situ hybridization (FISH) for physical mapping of the major (18S rDNA) and minor (5S rDNA) ribosomal genes...
December 23, 2016: Genetics and Molecular Research: GMR
https://www.readbyqxmd.com/read/28078514/the-molecular-basis-of-the-organization-of-repetitive-dna-containing-constitutive-heterochromatin-in-mammals
#7
REVIEW
Gohei Nishibuchi, Jérôme Déjardin
Constitutive heterochromatin is composed mainly of repetitive elements and represents the typical inert chromatin structure in eukaryotic cells. Approximately half of the mammalian genome is made of repeat sequences, such as satellite DNA, telomeric DNA, and transposable elements. As essential genes are not present in these regions, most of these repeat sequences were considered as junk DNA in the past. However, it is now clear that these regions are essential for chromosome stability and the silencing of neighboring genes...
January 11, 2017: Chromosome Research
https://www.readbyqxmd.com/read/28068183/nucleolar-aggresomes-mediate-release-of-pericentric-heterochromatin-and-nuclear-destruction-of-genotoxically-treated-cancer-cells
#8
Kristine Salmina, Anda Huna, Inna Inashkina, Alexander Belyayev, Jekabs Krigerts, Ladislava Pastova, Alejandro Vazquez-Martin, Jekaterina Erenpreisa
The role of the nucleolus and autophagy in maintenance of nuclear integrity is poorly understood. In addition, the mechanisms of nuclear destruction in cancer cells senesced after conventional chemotherapy are unclear. In an attempt to elucidate these issues, we studied teratocarcinoma PA1 cells treated with Etoposide (ETO), focussing on the nucleolus. Following treatment, most cells enter G2 arrest, display persistent DNA damage and activate p53, senescence, and macroautophagy markers. 2-5 µm sized nucleolar aggresomes (NoA) containing fibrillarin (FIB) and damaged rDNA, colocalised with ubiquitin, pAMPK, and LC3-II emerge, accompanied by heterochromatin fragments, when translocated perinuclearly...
January 9, 2017: Nucleus
https://www.readbyqxmd.com/read/28067760/dna-methylation-targeting-the-dnmt-hmt-crosstalk-challenge
#9
REVIEW
Omar Castillo-Aguilera, Patrick Depreux, Ludovic Halby, Paola B Arimondo, Laurence Goossens
Chromatin can adopt a decondensed state linked to gene transcription (euchromatin) and a condensed state linked to transcriptional repression (heterochromatin). These states are controlled by epigenetic modulators that are active on either the DNA or the histones and are tightly associated to each other. Methylation of both DNA and histones is involved in either the activation or silencing of genes and their crosstalk. Since DNA/histone methylation patterns are altered in cancers, molecules that target these modifications are interesting therapeutic tools...
January 5, 2017: Biomolecules
https://www.readbyqxmd.com/read/28064188/upset-the-drosophila-homologue-of-set3-is-required-for-viability-and-the-proper-balance-of-active-and-repressive-chromatin-marks
#10
Kyle A McElroy, Youngsook Lucy Jung, Barry M Zee, Charlotte I Wang, Peter J Park, Mitzi I Kuroda
Chromatin plays a critical role in faithful implementation of gene expression programs. Different post-translational modifications of histone proteins reflect the underlying state of gene activity, and many chromatin proteins write, erase, bind, or are repelled by these histone marks. One such protein is UpSET, the Drosophila homolog of yeast Set3 and mammalian KMT2E (MLL5). Here we show that UpSET is necessary for the proper balance between active and repressed states. Using CRISPR/Cas-9 editing, we generated S2 cells which are mutant for upset We found that loss of UpSET is tolerated in S2 cells, but that heterochromatin is misregulated, as evidenced by a strong decrease in H3K9me2 levels assessed by bulk histone post-translational modification quantification...
January 6, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/28064165/nutritional-control-of-chronological-aging-and-heterochromatin-in-saccharomyces-cerevisiae
#11
David F McCleary, Jasper Rine
Calorie restriction extends lifespan in organisms as diverse as yeast and mammals through incompletely understood mechanism(s). The role of NAD(+)-dependent deacetylases, known as Sirtuins, in this process, particularly in the yeast S. cerevisiae is controversial. We measured chronological lifespan of wild-type and sir2Δ strains over a higher glucose range than typically used for studying yeast calorie restriction. sir2Δ extended lifespan in high-glucose complete minimal medium, and had little effect in low glucose medium, revealing a partial role for Sir2 in the calorie restriction response under these conditions...
January 6, 2017: Genetics
https://www.readbyqxmd.com/read/28062559/atrx-and-daxx-mechanisms-and-mutations
#12
Michael A Dyer, Zulekha A Qadeer, David Valle-Garcia, Emily Bernstein
Recent genome sequencing efforts in a variety of cancers have revealed mutations and/or structural alterations in ATRX and DAXX, which together encode a complex that deposits histone variant H3.3 into repetitive heterochromatin. These regions include retrotransposons, pericentric heterochromatin, and telomeres, the latter of which show deregulation in ATRX/DAXX-mutant tumors. Interestingly, ATRX and DAXX mutations are often found in pediatric tumors, suggesting a particular developmental context in which these mutations drive disease...
January 6, 2017: Cold Spring Harbor Perspectives in Medicine
https://www.readbyqxmd.com/read/28059589/an-hp1-isoform-specific-feedback-mechanism-regulates-suv39h1-activity-under-stress-conditions
#13
Helena Raurell-Vila, Laia Bosch-Presegue, Jessica Gonzalez, Noriko Kane-Goldsmith, Carmen Casal, Jeremy P Brown, Anna Marazuela-Duque, Prim B Singh, Lourdes Serrano, Alejandro Vaquero
The presence of H3K9me3 and heterochromatin protein 1 (HP1) are hallmarks of heterochromatin conserved in eukaryotes. The spreading and maintenance of H3K9me3 is effected by the functional interplay between the H3K9me3-specific histone methyltransferase Suv39h1 and HP1. This interplay is complex in mammals because the three HP1 isoforms, HP1α, β, and γ, are thought to play a redundant role in Suv39h1-dependent deposition of H3K9me3 in pericentric heterochromatin (PCH). Here, we demonstrate that despite this redundancy, HP1α and, to a lesser extent, HP1γ have a closer functional link to Suv39h1, compared to HP1β...
January 6, 2017: Epigenetics: Official Journal of the DNA Methylation Society
https://www.readbyqxmd.com/read/28057760/chromatin-and-lamin-a-determine-two-different-mechanical-response-regimes-of-the-cell-nucleus
#14
Andrew D Stephens, Edward J Banigan, Stephen A Adam, Robert D Goldman, John F Marko
The cell nucleus must continually resist and respond to inter- and intracellular mechanical forces to transduce mechanical signals and maintain proper genome organization and expression. Altered nuclear mechanics are associated with many human diseases, including heart disease, progeria, and cancer. Chromatin and nuclear envelope A-type lamin proteins are known to be key nuclear mechanical components perturbed in these diseases, but their distinct mechanical contributions are not known. Here, we directly establish the separate roles of chromatin and lamin A/C and show that they determine two distinct mechanical regimes via micromanipulation of single isolated nuclei...
January 5, 2017: Molecular Biology of the Cell
https://www.readbyqxmd.com/read/28056360/nuclear-envelope-localization-of-lemd2-is-developmentally-dynamic-and-lamin-a-c-dependent-yet-insufficient-for-heterochromatin-tethering
#15
Katharina Thanisch, Congdi Song, Dieter Engelkamp, Jeannette Koch, Audrey Wang, Einar Hallberg, Roland Foisner, Heinrich Leonhardt, Colin L Stewart, Boris Joffe, Irina Solovei
Peripheral heterochromatin in mammalian nuclei is tethered to the nuclear envelope by at least two mechanisms here referred to as the A- and B-tethers. The A-tether includes lamins A/C and additional unknown components presumably INM protein(s) interacting with both lamins A/C and chromatin. The B-tether includes the inner nuclear membrane (INM) protein Lamin B-receptor, which binds B-type lamins and chromatin. Generally, at least one of the tethers is always present in the nuclear envelope of mammalian cells...
January 2, 2017: Differentiation; Research in Biological Diversity
https://www.readbyqxmd.com/read/28052240/trim28-controls-a-gene-regulatory-network-based-on-endogenous-retroviruses-in-human-neural-progenitor-cells
#16
Per Ludvik Brattås, Marie E Jönsson, Liana Fasching, Jenny Nelander Wahlestedt, Mansoureh Shahsavani, Ronny Falk, Anna Falk, Patric Jern, Malin Parmar, Johan Jakobsson
Endogenous retroviruses (ERVs), which make up 8% of the human genome, have been proposed to participate in the control of gene regulatory networks. In this study, we find a region- and developmental stage-specific expression pattern of ERVs in the developing human brain, which is linked to a transcriptional network based on ERVs. We demonstrate that almost 10,000, primarily primate-specific, ERVs act as docking platforms for the co-repressor protein TRIM28 in human neural progenitor cells, which results in the establishment of local heterochromatin...
January 3, 2017: Cell Reports
https://www.readbyqxmd.com/read/28051130/the-histone-3-lysine-9-methyltransferase-inhibitor-chaetocin-improves-prognosis-in-a-rat-model-of-high-salt-diet-induced-heart-failure
#17
Tomohiko Ono, Naomi Kamimura, Tomohiro Matsuhashi, Toshihiro Nagai, Takahiko Nishiyama, Jin Endo, Takako Hishiki, Tsuyoshi Nakanishi, Noriaki Shimizu, Hirotoshi Tanaka, Shigeo Ohta, Makoto Suematsu, Masaki Ieda, Motoaki Sano, Keiichi Fukuda, Ruri Kaneda
Histone acetylation has been linked to cardiac hypertrophy and heart failure. However, the pathological implications of changes in histone methylation and the effects of interventions with histone methyltransferase inhibitors for heart failure have not been fully clarified. Here, we focused on H3K9me3 status in the heart and investigated the effects of the histone H3K9 methyltransferase inhibitor chaetocin on prognoses in Dahl salt-sensitive rats, an animal model of chronic heart failure. Chaetocin prolonged survival and restored mitochondrial dysfunction...
January 4, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28049722/the-linc-complex-contributes-to-heterochromatin-organisation-and-transcriptional-gene-silencing-in-plants
#18
Axel Poulet, Céline Duc, Maxime Voisin, Sophie Desset, Sylvie Tutois, Emmanuel Vanrobays, Matthias Benoit, David E Evans, Aline V Probst, Christophe Tatout
The LInker of Nucleoskeleton and Cytoskeleton (LINC) complex is an evolutionary well-conserved protein bridge connecting the cytoplasmic and nuclear compartments across the nuclear membrane. While recent data support its function in nuclear morphology and meiosis, its implication in chromatin organisation has not been studied in plants. Here 3D imaging methods have been used to investigate nuclear morphology and chromatin organisation in interphase nuclei of the model plant Arabidopsis thaliana, in which heterochromatin cluster in conspicuous chromatin domains called chromocentres...
January 3, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28040729/polycomb-repressive-complex-1-provides-a-molecular-explanation-for-repeat-copy-number-dependency-in-fshd-muscular-dystrophy
#19
Valentina Casa, Valeria Runfola, Stefano Micheloni, Arif Aziz, F Jeffrey Dilworth, Davide Gabellini
Repression of repetitive elements is crucial to preserve genome integrity and has been traditionally ascribed to constitutive heterochromatin pathways. FacioScapuloHumeral Muscular Dystrophy (FSHD), one of the most common myopathies, is characterized by a complex interplay of genetic and epigenetic events. The main FSHD form is linked to reduced copy number of the D4Z4 macrosatellite repeat on 4q35, causing loss of silencing and aberrant expression of the D4Z4-embedded DUX4 gene leading to disease. By an unknown mechanism, D4Z4 copy-number correlates with FSHD phenotype...
December 30, 2016: Human Molecular Genetics
https://www.readbyqxmd.com/read/28028228/large-scale-heterochromatin-remodeling-linked-to-overreplication-associated-dna-damage
#20
Wei Feng, Christopher J Hale, Ryan S Over, Shawn J Cokus, Steven E Jacobsen, Scott D Michaels
Previously, we have shown that loss of the histone 3 lysine 27 (H3K27) monomethyltransferases ARABIDOPSIS TRITHORAX-RELATED 5 (ATXR5) and ATXR6 (ATXR6) results in the overreplication of heterochromatin. Here we show that the overreplication results in DNA damage and extensive chromocenter remodeling into unique structures we have named "overreplication-associated centers" (RACs). RACs have a highly ordered structure with an outer layer of condensed heterochromatin, an inner layer enriched in the histone variant H2AX, and a low-density core containing foci of phosphorylated H2AX (a marker of double-strand breaks) and the DNA-repair enzyme RAD51...
December 27, 2016: Proceedings of the National Academy of Sciences of the United States of America
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