2,597 results match your criteria heterochromatin structure

ATRX limits the accessibility of histone H3-occupied HSV genomes during lytic infection.

PLoS Pathog 2021 Apr 28;17(4):e1009567. Epub 2021 Apr 28.

Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts, United States of America.

Histones are rapidly loaded on the HSV genome upon entry into the nucleus of human fibroblasts, but the effects of histone loading on viral replication have not been fully defined. We showed recently that ATRX is dispensable for de novo deposition of H3 to HSV genomes after nuclear entry but restricted infection through maintenance of viral heterochromatin. To further investigate the roles that ATRX and other histone H3 chaperones play in restriction of HSV, we infected human fibroblasts that were systematically depleted of nuclear H3 chaperones. Read More

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Toxic Y chromosome: Increased repeat expression and age-associated heterochromatin loss in male Drosophila with a young Y chromosome.

PLoS Genet 2021 Apr 22;17(4):e1009438. Epub 2021 Apr 22.

Department of Integrative Biology, University of California Berkeley, Berkeley, California, United States of America.

Sex-specific differences in lifespan are prevalent across the tree of life and influenced by heteromorphic sex chromosomes. In species with XY sex chromosomes, females often outlive males. Males and females can differ in their overall repeat content due to the repetitive Y chromosome, and repeats on the Y might lower survival of the heterogametic sex (toxic Y effect). Read More

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HP1 drives de novo 3D genome reorganization in early Drosophila embryos.

Nature 2021 Apr 14. Epub 2021 Apr 14.

Max Planck Institute of Immunobiology and Epigenetics, Freiburg im Breisgau, Germany.

Fundamental features of 3D genome organization are established de novo in the early embryo, including clustering of pericentromeric regions, the folding of chromosome arms and the segregation of chromosomes into active (A-) and inactive (B-) compartments. However, the molecular mechanisms that drive de novo organization remain unknown. Here, by combining chromosome conformation capture (Hi-C), chromatin immunoprecipitation with high-throughput sequencing (ChIP-seq), 3D DNA fluorescence in situ hybridization (3D DNA FISH) and polymer simulations, we show that heterochromatin protein 1a (HP1a) is essential for de novo 3D genome organization during Drosophila early development. Read More

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Dynamics of transcription-mediated conversion from euchromatin to facultative heterochromatin at the Xist promoter by Tsix.

Cell Rep 2021 Mar;34(13):108912

Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan. Electronic address:

The fine-scale dynamics from euchromatin (EC) to facultative heterochromatin (fHC) has remained largely unclear. Here, we focus on Xist and its silencing initiator Tsix as a paradigm of transcription-mediated conversion from EC to fHC. In mouse epiblast stem cells, induction of Tsix recapitulates the conversion at the Xist promoter. Read More

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Regulation of HP1 protein by phosphorylation during transcriptional repression and cell cycle.

J Biochem 2021 Mar 27. Epub 2021 Mar 27.

Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, JAPAN, Tel: 81-3-5316-3220.

HP1 (Heterochromatin Protein 1), a key factor for the formation of heterochromatin, binds to the methylated lysine 9 of histone H3 (H3K9me), and represses transcription. While the H3K9me mark and HP1 binding are thought to be faithfully propagated to daughter cells, the heterochromatin structure could be dynamically regulated during cell cycle. As evidenced by the well-known phenomenon called Position Effect Variegation (PEV), heterochromatin structure is dynamically and stochastically altered during developmental processes, and thus the expression of genes within or in the vicinity of heterochromatin could be affected by mutations in factors regulating DNA replication as well as by other epigenetic factors. Read More

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Transcriptional regulation of telomeric repeat-containing RNA by acridine derivatives.

RNA Biol 2021 Mar 22:1-17. Epub 2021 Mar 22.

School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou University City, Guangzhou and P.R. China.

Telomere is a specialized DNA-protein complex that plays an important role in maintaining chromosomal integrity. Shelterin is a protein complex formed by six different proteins, with telomeric repeat factors 1 (TRF1) and 2 (TRF2) binding to double-strand telomeric DNA. Telomeric DNA consists of complementary G-rich and C-rich repeats, which could form G-quadruplex and intercalated motif (i-motif), respectively, during cell cycle. Read More

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Broken, silent, and in hiding: Tamed endogenous pararetroviruses escape elimination from the genome of sugar beet (Beta vulgaris).

Ann Bot 2021 Mar 17. Epub 2021 Mar 17.

Institute of Botany, Technische Universität Dresden, Dresden, Germany.

Background And Aims: Endogenous pararetroviruses (EPRVs) are widespread components of plant genomes that originated from episomal DNA viruses of the Caulimoviridae family. Due to fragmentation and rearrangements, most EPRVs have lost their ability to replicate through reverse transcription and to initiate viral infection. Similar to the closely related retrotransposons, extant EPRVs were retained and often amplified in plant genomes for several million years. Read More

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Brain Ultrastructure: Putting the Pieces Together.

Front Cell Dev Biol 2021 18;9:629503. Epub 2021 Feb 18.

Division of Medical Sciences, University of Victoria, Victoria, BC, Canada.

Unraveling the fine structure of the brain is important to provide a better understanding of its normal and abnormal functioning. Application of high-resolution electron microscopic techniques gives us an unprecedented opportunity to discern details of the brain parenchyma at nanoscale resolution, although identifying different cell types and their unique features in two-dimensional, or three-dimensional images, remains a challenge even to experts in the field. This article provides insights into how to identify the different cell types in the central nervous system, based on nuclear and cytoplasmic features, amongst other unique characteristics. Read More

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February 2021

HP1β carries an acidic linker domain and requires H3K9me3 for phase separation.

Nucleus 2021 12;12(1):44-57

Center for Molecular Biosystems (BioSysM), Faculty of Biology, Ludwig-Maximilians-Universität München, Munich, Germany.

Liquid-liquid phase separation (LLPS) mediated formation of membraneless organelles has been proposed to coordinate biological processes in space and time. Previously, the formation of phase-separated droplets was described as a unique property of HP1α. Here, we demonstrate that the positive net charge of the intrinsically disordered hinge region (IDR-H) of HP1 proteins is critical for phase separation and that the exchange of four acidic amino acids is sufficient to confer LLPS properties to HP1β. Read More

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December 2021

A New Variant B Chromosome in Auchenipteridae: The Role of (GATA)n and (TTAGGG)n Sequences in Understanding the Evolution of Supernumeraries in Trachelyopterus.

Cytogenet Genome Res 2021 Feb 18:1-12. Epub 2021 Feb 18.

Centro de Ciências Biológicas e da Saúde, Universidade Estadual do Oeste do Paraná, Cascavel, Brazil,

Basic and molecular cytogenetic techniques were carried out in 3 Neotropical region populations of catfishes, two of Trachelyopterus galeatus (one from the marshlands of Paraguay River basin and another from Lago Catalão, Amazon River basin) and one of Trachelyopterus porosus, a sympatric population to T. galeatus from the Amazon River basin. This study aimed to describe and understand the structure and evolution of Trachelyopterus B chromosomes, mainly through physical mapping of repetitive elements. Read More

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February 2021

Light and shadow on the mechanisms of integration site selection in yeast Ty retrotransposon families.

Curr Genet 2021 Feb 15. Epub 2021 Feb 15.

INSERM U944, CNRS UMR 7212, Genomes and Cell Biology of Disease Unit, Institut de Recherche Saint-Louis, Université de Paris, Hôpital Saint-Louis, Paris, France.

Transposable elements are ubiquitous in genomes. Their successful expansion depends in part on their sites of integration in their host genome. In Saccharomyces cerevisiae, evolution has selected various strategies to target the five Ty LTR-retrotransposon families into gene-poor regions in a genome, where coding sequences occupy 70% of the DNA. Read More

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February 2021

A lamin A/C variant causing striated muscle disease provides insights into filament organization.

J Cell Sci 2021 Mar 22;134(6). Epub 2021 Mar 22.

Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland

The gene encodes the A-type lamins, which polymerize into ∼3.5-nm-thick filaments and, together with B-type lamins and associated proteins, form the nuclear lamina. Mutations in cause a wide variety of pathologies. Read More

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Pathogenic LMNA variants disrupt cardiac lamina-chromatin interactions and de-repress alternative fate genes.

Cell Stem Cell 2021 May 1;28(5):938-954.e9. Epub 2021 Feb 1.

Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Department of Cell and Developmental Biology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Penn Cardiovascular Institute, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA; Institute for Regenerative Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA 19014, USA. Electronic address:

Pathogenic mutations in LAMIN A/C (LMNA) cause abnormal nuclear structure and laminopathies. These diseases have myriad tissue-specific phenotypes, including dilated cardiomyopathy (DCM), but how LMNA mutations result in tissue-restricted disease phenotypes remains unclear. We introduced LMNA mutations from individuals with DCM into human induced pluripotent stem cells (hiPSCs) and found that hiPSC-derived cardiomyocytes, in contrast to hepatocytes or adipocytes, exhibit aberrant nuclear morphology and specific disruptions in peripheral chromatin. Read More

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The 20S proteasome activator PA28γ controls the compaction of chromatin.

J Cell Sci 2021 Feb 1;134(3). Epub 2021 Feb 1.

Centre de Recherche de Biologie cellulaire de Montpellier (CRBM), Université de Montpellier, CNRS, 34293 Montpellier, France

PA28γ (also known as PSME3), a nuclear activator of the 20S proteasome, is involved in the degradation of several proteins regulating cell growth and proliferation and in the dynamics of various nuclear bodies, but its precise cellular functions remain unclear. Here, using a quantitative FLIM-FRET based microscopy assay monitoring close proximity between nucleosomes in living human cells, we show that PA28γ controls chromatin compaction. We find that its depletion induces a decompaction of pericentromeric heterochromatin, which is similar to what is observed upon the knockdown of HP1β (also known as CBX1), a key factor of the heterochromatin structure. Read More

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February 2021

Ultra-structural analysis and morphological changes during the differentiation of trophozoite to cyst in Entamoeba invadens.

Mol Biochem Parasitol 2021 03 29;242:111363. Epub 2021 Jan 29.

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, 110067, India. Electronic address:

Entamoeba histolytica, a pathogenic parasite, is the causative organism of amoebiasis and uses human colon to complete its life cycle. It destroys intestinal tissue leading to invasive disease. Since it does not form cyst in culture medium, a reptilian parasite Entamoeba invadens serves as the model system to study encystation. Read More

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Emerging roles of centromeric RNAs in centromere formation and function.

Genes Genomics 2021 Mar 1;43(3):217-226. Epub 2021 Feb 1.

State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Innovation Academy for Seed Design, Chinese Academy of Sciences, Beijing, 100101, China.

Background: Centromeres are specialized chromosomal domains involved in kinetochore formation and faithful chromosome segregation. Despite a high level of functional conservation, centromeres are not identified by DNA sequences, but by epigenetic means. Universally, centromeres are typically formed on highly repetitive DNA, which were previously considered to be silent. Read More

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The human origin recognition complex is essential for pre-RC assembly, mitosis, and maintenance of nuclear structure.

Elife 2021 Feb 1;10. Epub 2021 Feb 1.

Cold Spring Harbor Laboratory, Cold Spring Harbor, United States.

The origin recognition complex (ORC) cooperates with CDC6, MCM2-7, and CDT1 to form pre-RC complexes at origins of DNA replication. Here, using tiling-sgRNA CRISPR screens, we report that each subunit of ORC and CDC6 is essential in human cells. Using an auxin-inducible degradation system, we created stable cell lines capable of ablating ORC2 rapidly, revealing multiple cell division cycle phenotypes. Read More

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February 2021

Metabolic regulation of telomere silencing by SESAME complex-catalyzed H3T11 phosphorylation.

Nat Commun 2021 01 26;12(1):594. Epub 2021 Jan 26.

State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, Hubei, 430062, China.

Telomeres are organized into a heterochromatin structure and maintenance of silent heterochromatin is required for chromosome stability. How telomere heterochromatin is dynamically regulated in response to stimuli remains unknown. Pyruvate kinase Pyk1 forms a complex named SESAME (Serine-responsive SAM-containing Metabolic Enzyme complex) to regulate gene expression by phosphorylating histone H3T11 (H3pT11). Read More

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January 2021

DNA methylation-linked chromatin accessibility affects genomic architecture in .

Proc Natl Acad Sci U S A 2021 Feb;118(5)

Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA 90095;

DNA methylation is a major epigenetic modification found across species and has a profound impact on many biological processes. However, its influence on chromatin accessibility and higher-order genome organization remains unclear, particularly in plants. Here, we present genome-wide chromatin accessibility profiles of 18 mutants that are deficient in CG, CHG, or CHH DNA methylation. Read More

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February 2021

Formation of a multi-layered 3-dimensional structure of the heterochromatin compartment during early mammalian development.

Dev Growth Differ 2021 Jan 3;63(1):5-17. Epub 2021 Feb 3.

Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, Japan.

During embryogenesis in mammals, the 3-dimensional (3D) genome organization changes globally in parallel with transcription changes in a cell-type specific manner. This involves the progressive formation of heterochromatin, the best example of which is the inactive X chromosome (Xi) in females, originally discovered as a compact 3D structure at the nuclear periphery known as the Barr body. The heterochromatin formation on the autosomes and the Xi is tightly associated with the differentiation state and the developmental potential of cells, making it an ideal readout of the cellular epigenetic state. Read More

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January 2021

IMITATION SWITCH is required for normal chromatin structure and gene repression in PRC2 target domains.

Proc Natl Acad Sci U S A 2021 Jan;118(4)

Department of Microbiology, University of Georgia, Athens, GA 30602;

Polycomb Group (PcG) proteins are part of an epigenetic cell memory system that plays essential roles in multicellular development, stem cell biology, X chromosome inactivation, and cancer. In animals, plants, and many fungi, Polycomb Repressive Complex 2 (PRC2) catalyzes trimethylation of histone H3 lysine 27 (H3K27me3) to assemble transcriptionally repressed facultative heterochromatin. PRC2 is structurally and functionally conserved in the model fungus , and recent work in this organism has generated insights into PRC2 control and function. Read More

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January 2021

Rbm10 facilitates heterochromatin assembly via the Clr6 HDAC complex.

Epigenetics Chromatin 2021 Jan 19;14(1). Epub 2021 Jan 19.

Department of Biology, New York University, New York, NY, 10003-6688, USA.

Splicing factors have recently been shown to be involved in heterochromatin formation, but their role in controlling heterochromatin structure and function remains poorly understood. In this study, we identified a fission yeast homologue of human splicing factor RBM10, which has been linked to TARP syndrome. Overexpression of Rbm10 in fission yeast leads to strong global intron retention. Read More

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January 2021

Beyond the Nucleosome: Nucleosome-Protein Interactions and Higher Order Chromatin Structure.

J Mol Biol 2021 03 16;433(6):166827. Epub 2021 Jan 16.

NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, the Netherlands. Electronic address:

The regulation of chromatin biology ultimately depends on the manipulation of its smallest subunit, the nucleosome. The proteins that bind and operate on the nucleosome do so, while their substrate is part of a polymer embedded in the dense nuclear environment. Their molecular interactions must in some way be tuned to deal with this complexity. Read More

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Molecular Aspects of Senescence and Organismal Ageing-DNA Damage Response, Telomeres, Inflammation and Chromatin.

Int J Mol Sci 2021 Jan 8;22(2). Epub 2021 Jan 8.

Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland.

Cells can become senescent in response to stress. Senescence is a process characterised by a stable proliferative arrest. Sometimes it can be beneficial-for example, it can suppress tumour development or take part in tissue repair. Read More

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January 2021

Pilocarpine-induced seizures associate with modifications of LSD1/CoREST/HDAC1/2 epigenetic complex and repressive chromatin in mice hippocampus.

Biochem Biophys Rep 2021 Mar 29;25:100889. Epub 2020 Dec 29.

Department of Cellular and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Católica de Chile, Santiago, Chile.

Epilepsy is a neurological disorder of genetic or environmental origin characterized by recurrent spontaneous seizures. A rodent model of temporal lobe epilepsy is induced by a single administration of pilocarpine, a non-selective cholinergic muscarinic receptor agonist. The molecular changes associated with pilocarpine-induced seizures are still poorly described. Read More

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A new emu genome illuminates the evolution of genome configuration and nuclear architecture of avian chromosomes.

Genome Res 2021 Mar 6;31(3):497-511. Epub 2021 Jan 6.

MOE Laboratory of Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory for Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou 310058, China.

Emu and other ratites are more informative than any other birds in reconstructing the evolution of the ancestral avian or vertebrate karyotype because of their much slower rate of genome evolution. Here, we generated a new chromosome-level genome assembly of a female emu, and estimated the tempo of chromosome evolution across major avian phylogenetic branches, by comparing it to chromosome-level genome assemblies of 11 other bird and one turtle species. We found ratites exhibited the lowest numbers of intra- and inter-chromosomal changes among birds since their divergence with turtles. Read More

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CENP-A Nucleosome is a Sensitive Allosteric Scaffold for DNA and Chromatin Factors.

J Mol Biol 2021 03 31;433(6):166789. Epub 2020 Dec 31.

Izmir Biomedicine and Genome Center, Dokuz Eylül University Health Campus, Balçova, Izmir 35330, Turkey. Electronic address:

Centromeric loci of chromosomes are defined by nucleosomes containing the histone H3 variant CENP-A, which bind their DNA termini more permissively than their canonical counterpart, a feature that is critical for the mitotic fidelity. A recent cryo-EM study demonstrated that the DNA termini of CENP-A nucleosomes, reconstituted with the Widom 601 DNA sequence, are asymmetrically flexible, meaning one terminus is more clearly resolved than the other. However, an earlier work claimed that both ends could be resolved in the presence of two stabilizing single chain variable fragment (scFv) antibodies per nucleosome, and thus are likely permanently bound to the histone octamer. Read More

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The INO80 Complex Regulates Epigenetic Inheritance of Heterochromatin.

Cell Rep 2020 Dec;33(13):108561

Department of Biological Sciences, Columbia University, New York, NY 10027, USA. Electronic address:

One key aspect of epigenetic inheritance is that chromatin structures can be stably inherited through generations after the removal of the signals that establish such structures. In fission yeast, the RNA interference (RNAi) pathway is critical for the targeting of histone methyltransferase Clr4 to pericentric repeats to establish heterochromatin. However, pericentric heterochromatin cannot be properly inherited in the absence of RNAi, suggesting the existence of mechanisms that counteract chromatin structure inheritance. Read More

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December 2020

Dark Matter of Primate Genomes: Satellite DNA Repeats and Their Evolutionary Dynamics.

Cells 2020 12 18;9(12). Epub 2020 Dec 18.

Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand.

A substantial portion of the primate genome is composed of non-coding regions, so-called "dark matter", which includes an abundance of tandemly repeated sequences called satellite DNA. Collectively known as the satellitome, this genomic component offers exciting evolutionary insights into aspects of primate genome biology that raise new questions and challenge existing paradigms. A complete human reference genome was recently reported with telomere-to-telomere human X chromosome assembly that resolved hundreds of dark regions, encompassing a 3. Read More

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December 2020

Targeting EHMT2/ G9a for cancer therapy: Progress and perspective.

Eur J Pharmacol 2021 Feb 19;893:173827. Epub 2020 Dec 19.

CSIR, Indian Institute of Integrative Medicine, Sanatnagar, 190005, Srinagar, Kashmir, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India. Electronic address:

Euchromatic histone lysine methyltransferase-2, also known as G9a, is a ubiquitously expressed SET domain-containing histone lysine methyltransferase linked with both facultative and constitutive heterochromatin formation and transcriptional repression. It is an essential developmental gene and reported to play role in embryonic development, establishment of proviral silencing in ES cells, tumor cell growth, metastasis, T-cell immune response, cocaine induced neural plasticity and cognition and adaptive behavior. It is mainly responsible for carrying out mono, di and tri methylation of histone H3K9 in euchromatin. Read More

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February 2021