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https://www.readbyqxmd.com/read/28341773/pml-protein-organizes-heterochromatin-domains-where-it-regulates-histone-h3-3-deposition-by-atrx-daxx
#1
Erwan Delbarre, Kristina Ivanauskiene, Jane Spirkoski, Akshay Shah, Kristin Vekterud, Jan Øivind Moskaug, Stig Ove Bøe, Lee Wong, Thomas Küntziger, Philippe Collas
Maintenance of chromatin homeostasis involves proper delivery of histone variants to the genome. The interplay between different chaperones regulating the supply of histone variants to distinct chromatin domains is largely undeciphered. We report here a role of promyelocytic leukemia (PML) protein in routing histone variant H3.3 to chromatin and in the organization of megabase-size heterochromatic PML-associated domains which we call PADs. Loss of PML alters the heterochromatic state of PADs by shifting the histone H3 methylation balance from K9me3 to K27me3...
March 24, 2017: Genome Research
https://www.readbyqxmd.com/read/28341771/small-chromosomal-regions-position-themselves-autonomously-according-to-their-chromatin-class
#2
Harmen Jan George van de Werken, Josien C de Haan, Yana Feodorova, Dominika Bijos, An Weuts, Koen Theunis, Sjoerd Holwerda, Wouter Meuleman, Ludo Pagie, Katharina Thanisch, Parveen Kumar, Heinrich Leonhardt, Peter Marynen, Bas van Steesel, Thierry Voet, Wouter de Laat, Irina Solovei, Boris Joffe
The spatial arrangement of chromatin is linked to the regulation of nuclear processes. One striking aspect of nuclear organization is the spatial segregation of heterochromatic and euchromatic domains. The mechanisms of this chromatin segregation are still poorly understood. In this work we investigated the link between the primary genomic sequence and chromatin domains. We analyzed the spatial intranuclear arrangement of a human artificial chromosome (HAC) in a xenospecific mouse background in comparison to an orthologous region of native mouse chromosome...
March 24, 2017: Genome Research
https://www.readbyqxmd.com/read/28334952/dnmt1-mutations-found-in-hsanie-patients-affect-interaction-with-uhrf1-and-neuronal-differentiation
#3
Martha Smets, Stephanie Link, Patricia Wolf, Katrin Schneider, Veronica Solis, Joel Ryan, Daniela Meilinger, Weihua Qin, Heinrich Leonhardt
DNMT1 is recruited to substrate sites by PCNA and UHRF1 to maintain DNA methylation after replication. The cell cycle dependent recruitment of DNMT1 is mediated by the PCNA-binding domain (PBD) and the targeting sequence (TS) within the N-terminal regulatory domain. The TS domain was found to be mutated in patients suffering from hereditary sensory and autonomic neuropathies with dementia and hearing loss (HSANIE) and autosomal dominant cerebellar ataxia deafness and narcolepsy (ADCA-DN) and is associated with global hypomethylation and site specific hypermethylation...
March 3, 2017: Human Molecular Genetics
https://www.readbyqxmd.com/read/28334768/repair-of-uv-induced-dna-lesions-in-natural-saccharomyces-cerevisiae-telomeres-is-moderated-by-sir2-and-sir3-and-inhibited-by-yku-sir4-interaction
#4
Laetitia Guintini, Maxime Tremblay, Martin Toussaint, Annie D'Amours, Ralf E Wellinger, Raymund J Wellinger, Antonio Conconi
Ultraviolet light (UV) causes DNA damage that is removed by nucleotide excision repair (NER). UV-induced DNA lesions must be recognized and repaired in nucleosomal DNA, higher order structures of chromatin and within different nuclear sub-compartments. Telomeric DNA is made of short tandem repeats located at the ends of chromosomes and their maintenance is critical to prevent genome instability. In Saccharomyces cerevisiae the chromatin structure of natural telomeres is distinctive and contingent to telomeric DNA sequences...
February 21, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28330620/mad2l2-promotes-open-chromatin-in-embryonic-stem-cells-and%C3%A2-derepresses-the-dppa3-locus
#5
Ali Rahjouei, Mehdi Pirouz, Michela Di Virgilio, Dirk Kamin, Michael Kessel
The chromatin of naive embryonic stem cells (ESCs) has a largely open configuration, as evident by the lack of condensed heterochromatin and the hypomethylation of DNA. Several molecular mechanisms promoting this constellation were previously identified. Here we present evidence for an important epigenetic function of MAD2L2, a protein originally known for its role in DNA damage repair, and for its requirement in germ cell development. We demonstrate using super-resolution microscopy that numerous MAD2L2 microfoci are exclusively associated with euchromatin, similar to other factors of the DNA damage response...
March 10, 2017: Stem Cell Reports
https://www.readbyqxmd.com/read/28320872/the-drosophila-daxx-like-protein-dlp-cooperates-with-asf1-for-h3-3-deposition-and-heterochromatin-formation
#6
Catherine Fromental-Ramain, Philippe Ramain, Ali Hamiche
Histone variants are non-allelic isoforms of canonical histones and they are deposited, in contrast to canonical histones, in a replication-independent (RI) manner. RI deposition of H3.3, a histone variant from the H3.3 family, is mediated in mammals by distinct pathways involving either the histone regulator A (HIRA) complex or the death-associated protein (DAXX)/α-thalassemia X-linked mental retardation protein (ATRX) complex. Here, we investigated the function of Drosophila DAXX Like Protein (DLP) by using both fly genetics approaches and protein biochemistry...
March 20, 2017: Molecular and Cellular Biology
https://www.readbyqxmd.com/read/28318821/snf2-family-protein-fft3-suppresses-nucleosome-turnover-to-promote-epigenetic-inheritance-and-proper-replication
#7
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/28317902/a-natural-tandem-array-alleviates-epigenetic-repression-of-ipa1-and-leads-to-superior-yielding-rice
#8
Lin Zhang, Hong Yu, Bin Ma, Guifu Liu, Jianjun Wang, Junmin Wang, Rongcun Gao, Jinjun Li, Jiyun Liu, Jing Xu, Yingying Zhang, Qun Li, Xuehui Huang, Jianlong Xu, Jianming Li, Qian Qian, Bin Han, Zuhua He, Jiayang Li
Super hybrid rice varieties with ideal plant architecture (IPA) have been critical in enhancing food security worldwide. However, the molecular mechanisms underlying their improved yield remain unclear. Here, we report the identification of a QTL, qWS8/ipa1-2D, in the super rice Yongyou12 (YY12) and related varieties. In-depth genetic molecular characterization of qWS8/ipa1-2D reveals that this newly identified QTL results from three distal naturally occurring tandem repeats upstream of IPA1, a key gene/locus previously shown to shape rice ideal plant architecture and greatly enhance grain yield...
March 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28315980/an-overview-of-cytogenetics-of-the-tribe-meliponini-hymenoptera-apidae
#9
REVIEW
Mara Garcia Tavares, Denilce Meneses Lopes, L A O Campos
The present study provides a comprehensive review of cytogenetic data on Meliponini and their chromosomal evolution. The compiled data show that only 104 species of stingless bees, representing 32 of the 54 living genera have been studied cytogenetically and that among these species, it is possible to recognize three main groups with n = 9, 15 and 17, respectively. The first group comprises the species of the genus Melipona, whereas karyotypes with n = 15 and n = 17 have been detected in species from different genera...
March 18, 2017: Genetica
https://www.readbyqxmd.com/read/28315870/the-hypermethylated-regions-in-avian-chromosomes
#10
Michael Schmid, Claus Steinlein
Chromosomal locations and amounts of 5-methylcytosine-rich chromosome regions were detected in the karyotypes of 13 bird species by indirect immunofluorescence using a monoclonal anti-5-methylcytosine antibody. These species belong to 7 orders and 10 families of modern (Neognathae) and primitive (Palaeognathae) birds and are characterized by macro- and microchromosomes as well as ZW sex chromosomes. In all 13 species, the hypermethylated chromosome segments are confined to constitutive heterochromatin. The chromosomal locations of hypermethylated DNA regions in the karyotypes are constant and species-specific...
March 18, 2017: Cytogenetic and Genome Research
https://www.readbyqxmd.com/read/28315713/maternal-senp7-programs-meiosis-architecture-and-embryo-survival-in-mouse
#11
ChunJie Huang, Di Wu, XiaoFei Jiao, Faheem Ahmed Khan, ChengLiang Xiong, XiaoMing Liu, Jing Yang, TaiLang Yin, LiJun Huo
Understanding the mechanisms underlying abnormal egg production and pregnancy loss is significant for human fertility. SENP7, a SUMO poly-chain editing enzyme, has been regarded as a mitotic regulator of heterochromatin integrity and DNA repair. Herein, we report the roles of SENP7 in mammalian reproductive scenario. Mouse oocytes deficient in SENP7 experienced meiotic arrest at prophase I and metaphase I stages, causing substantial decrease of mature eggs. Hyperaceylation and hypomethylation of histone H3 and up-regulation of Cdc14B/C accompanied by down-regulation of CyclinB1 and CyclinB2 were further recognized as contributors to defective M-phase entry and spindle assembly in oocytes...
March 15, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28315662/insights-into-the-establishment-of-chromatin-states-in-pluripotent-cells-from-studies-of-x-inactivation
#12
REVIEW
Andreas Postlmayr, Anton Wutz
Animal development entails the sequential and coordinated specialisation of cells. During cell differentiation transcription factors, cell signalling pathways and chromatin associated protein complexes cooperate in regulating the expression of a large number of genes. Here we review the present understanding of the establishment of chromatin states by focusing on X chromosome inactivation (XCI) as a model for facultative heterochromatin formation in female embryonic cells. The inactive X chromosome (Xi) is large enough to be investigated by biochenical and microscopy techniques...
March 15, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28302853/aggregation-of-the-whi3-protein-not-loss-of-heterochromatin-causes-sterility-in-old-yeast-cells
#13
Gavin Schlissel, Marek K Krzyzanowski, Fabrice Caudron, Yves Barral, Jasper Rine
In yeast, heterochromatin silencing is reported to decline in aging mother cells, causing sterility in old cells. This process is thought to reflect a decrease in the activity of the NAD(+) (oxidized nicotinamide adenine dinucleotide)-dependent deacetylase Sir2. We tested whether Sir2 becomes nonfunctional gradually or precipitously during aging. Unexpectedly, silencing of the heterochromatic HML and HMR loci was not lost during aging. Old cells could initiate a mating response; however, they were less sensitive to mating pheromone than were young cells because of age-dependent aggregation of Whi3, an RNA-binding protein controlling S-phase entry...
March 17, 2017: Science
https://www.readbyqxmd.com/read/28302748/smc5-6-is-required-for-the-formation-of-segregation-competent-bivalent-chromosomes-during-meiosis-i-in-mouse-oocytes
#14
Grace Hwang, Fengyun Sun, Marilyn O'Brien, John J Eppig, Mary Ann Handel, Philip W Jordan
SMC complexes include three major classes: cohesin, condensin, and SMC5/6. However, the localization pattern and genetic requirements for the SMC5/6 complex during mammalian oogenesis had not previously been examined. In mouse oocytes, the SMC5/6 complex is enriched at the pericentromeric heterochromatin, and also localizes along chromosome arms during meiosis. The infertility phenotypes of females with a Zp3-Cre-driven conditional knockout (cKO) of Smc5 demonstrated that maternally expressed SMC5 protein is essential for early embryogenesis...
March 16, 2017: Development
https://www.readbyqxmd.com/read/28301528/genome-wide-mapping-of-histone-h3k9me2-in-acute-myeloid-leukemia-reveals-large-chromosomal-domains-associated-with-massive-gene-silencing-and-sites-of-genome-instability
#15
Anna C Salzberg, Abigail Harris-Becker, Evgenya Y Popova, Nikki Keasey, Thomas P Loughran, David F Claxton, Sergei A Grigoryev
A facultative heterochromatin mark, histone H3 lysine 9 dimethylation (H3K9me2), which is mediated by histone methyltransferases G9a/GLP (EHMT2/1), undergoes dramatic rearrangements during myeloid cell differentiation as observed by chromatin imaging. To determine whether these structural transitions also involve genomic repositioning of H3K9me2, we used ChIP-sequencing to map genome-wide topography of H3K9me2 in normal human granulocytes, normal CD34+ hematopoietic progenitors, primary myeloblasts from acute myeloid leukemia (AML) patients, and a model leukemia cell line K562...
2017: PloS One
https://www.readbyqxmd.com/read/28301293/signatures-of-dna-target-selectivity-by-ets-transcription-factors
#16
Gregory M K Poon, Hye Mi Kim
The ETS family of transcription factors is a functionally heterogeneous group of gene regulators that share a structurally conserved, eponymous DNA-binding domain. DNA target specificity derives from combinatorial interactions with other proteins as well as intrinsic heterogeneity among ETS domains. Emerging evidence suggests molecular hydration as a fundamental feature that defines the intrinsic heterogeneity in DNA target selection and susceptibility to epigenetic DNA modification. This perspective invokes novel hypotheses in the regulation of ETS proteins in physiologic osmotic stress, their pioneering potential in heterochromatin, and the effects of passive and pharmacologic DNA demethylation on ETS regulation...
March 16, 2017: Transcription
https://www.readbyqxmd.com/read/28294943/a-team-of-heterochromatin-factors-collaborates-with-small-rna-pathways-to-combat-repetitive-elements-and-germline-stress
#17
Alicia N McMurchy, Przemyslaw Stempor, Tessa Gaarenstroom, Brian Wysolmerski, Yan Dong, Darya Aussianikava, Alex Appert, Ni Huang, Paulina Kolasinska-Zwierz, Alexandra Sapetschnig, Eric A Miska, Julie Ahringer
Repetitive sequences derived from transposons make up a large fraction of eukaryotic genomes and must be silenced to protect genome integrity. Repetitive elements are often found in heterochromatin; however, the roles and interactions of heterochromatin proteins in repeat regulation are poorly understood. Here we show that a diverse set of C. elegans heterochromatin proteins act together with the piRNA and nuclear RNAi pathways to silence repetitive elements and prevent genotoxic stress in the germ line. Mutants in genes encoding HPL-2/HP1, LIN-13, LIN-61, LET-418/Mi-2, and H3K9me2 histone methyltransferase MET-2/SETDB1 also show functionally redundant sterility, increased germline apoptosis, DNA repair defects, and interactions with small RNA pathways...
March 15, 2017: ELife
https://www.readbyqxmd.com/read/28293543/the-tudor-staphylococcal-nuclease-protein-of-entamoeba-histolytica-participates-in-transcription-regulation-and-stress-response
#18
Javier Cázares-Apátiga, Christian Medina-Gómez, Bibiana Chávez-Munguía, Mercedes Calixto-Gálvez, Esther Orozco, Carlos Vázquez-Calzada, Aarón Martínez-Higuera, Mario A Rodríguez
Entamoeba histolytica is the protozoa parasite responsible of human amoebiasis, disease that causes from 40,000 to 100,000 deaths annually worldwide. However, few are known about the expression regulation of molecules involved in its pathogenicity. Transcription of some virulence-related genes is positively controlled by the cis-regulatory element named URE1. Previously we identified the transcription factor that binds to URE1, which displayed a nuclear and cytoplasmic localization. This protein belongs to the Tudor Staphyococcal nuclease (TSN) family, which in other systems participates in virtually all pathways of gene expression, suggesting that this amoebic transcription factor (EhTSN; former EhURE1BP) could also play multiple functions in E...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28293300/silencing-markers-are-retained-on-pericentric-heterochromatin-during-murine-primordial-germ-cell-development
#19
Aristea Magaraki, Godfried van der Heijden, Esther Sleddens-Linkels, Leonidas Magarakis, Wiggert A van Cappellen, Antoine H F M Peters, Joost Gribnau, Willy M Baarends, Maureen Eijpe
BACKGROUND: In the nuclei of most mammalian cells, pericentric heterochromatin is characterized by DNA methylation, histone modifications such as H3K9me3 and H4K20me3, and specific binding proteins like heterochromatin-binding protein 1 isoforms (HP1 isoforms). Maintenance of this specialized chromatin structure is of great importance for genome integrity and for the controlled repression of the repetitive elements within the pericentric DNA sequence. Here we have studied histone modifications at pericentric heterochromatin during primordial germ cell (PGC) development using different fixation conditions and fluorescent immunohistochemical and immunocytochemical protocols...
2017: Epigenetics & Chromatin
https://www.readbyqxmd.com/read/28293299/identification-of-epigenetic-signature-associated-with-alpha-thalassemia-mental-retardation-x-linked-syndrome
#20
Laila C Schenkel, Kristin D Kernohan, Arran McBride, Ditta Reina, Amanda Hodge, Peter J Ainsworth, David I Rodenhiser, Guillaume Pare, Nathalie G Bérubé, Cindy Skinner, Kym M Boycott, Charles Schwartz, Bekim Sadikovic
BACKGROUND: Alpha thalassemia/mental retardation X-linked syndrome (ATR-X) is caused by a mutation at the chromatin regulator gene ATRX. The mechanisms involved in the ATR-X pathology are not completely understood, but may involve epigenetic modifications. ATRX has been linked to the regulation of histone H3 and DNA methylation, while mutations in the ATRX gene may lead to the downstream epigenetic and transcriptional effects. Elucidating the underlying epigenetic mechanisms altered in ATR-X will provide a better understanding about the pathobiology of this disease, as well as provide novel diagnostic biomarkers...
2017: Epigenetics & Chromatin
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