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Drosophila chromatin

Kumaran Nagalingam, Michał T Lorenc, Sahana Manoli, Stephen L Cameron, Anthony R Clarke, Kevin J Dudley
Interactions between DNA and proteins located in the cell nucleus play an important role in controlling physiological processes by specifying, augmenting and regulating context-specific transcription events. Chromatin immunoprecipitation (ChIP) is a widely used methodology to study DNA-protein interactions and has been successfully used in various cell types for over three decades. More recently, by combining ChIP with genomic screening technologies and Next Generation Sequencing (e.g. ChIP-seq), it has become possible to profile DNA-protein interactions (including covalent histone modifications) across entire genomes...
2018: PloS One
Sigrun Schmähling, Arno Meiler, Yoonjung Lee, Arif Mohammed, Katja Finkl, Katharina Tauscher, Lars Israel, Marc Borath, Julia Philippou-Massier, Helmut Blum, Bianca Habermann, Axel Imhof, Ji-Joon Song, Jürg Müller
The Drosophila Ash1 protein is a trithorax-group (trxG) regulator that antagonizes Polycomb repression at HOX genes. Ash1 di-methylates lysine 36 in histone H3 (H3K36me2) but how this activity is controlled and at which genes it functions is not well understood. We show that Ash1 protein purified from Drosophila exists in a complex with MRG15 and Caf1 that we named AMC. In Drosophila and human AMC, MRG15 binds a conserved FxLP motif near the Ash1 SET domain and stimulates H3K36 di-methylation on nucleosomes...
March 14, 2018: Development
Darren A Cusanovich, James P Reddington, David A Garfield, Riza M Daza, Delasa Aghamirzaie, Raquel Marco-Ferreres, Hannah A Pliner, Lena Christiansen, Xiaojie Qiu, Frank J Steemers, Cole Trapnell, Jay Shendure, Eileen E M Furlong
Understanding how gene regulatory networks control the progressive restriction of cell fates is a long-standing challenge. Recent advances in measuring gene expression in single cells are providing new insights into lineage commitment. However, the regulatory events underlying these changes remain unclear. Here we investigate the dynamics of chromatin regulatory landscapes during embryogenesis at single-cell resolution. Using single-cell combinatorial indexing assay for transposase accessible chromatin with sequencing (sci-ATAC-seq), we profiled chromatin accessibility in over 20,000 single nuclei from fixed Drosophila melanogaster embryos spanning three landmark embryonic stages: 2-4 h after egg laying (predominantly stage 5 blastoderm nuclei), when each embryo comprises around 6,000 multipotent cells; 6-8 h after egg laying (predominantly stage 10-11), to capture a midpoint in embryonic development when major lineages in the mesoderm and ectoderm are specified; and 10-12 h after egg laying (predominantly stage 13), when each of the embryo's more than 20,000 cells are undergoing terminal differentiation...
March 14, 2018: Nature
Yikai Huang, Wukui Zhao, Congcong Wang, Yaru Zhu, Mengjie Liu, Huan Tong, Yin Xia, Qing Jiang, Jinzhong Qin
Though genetic data suggest that Polycomb group proteins (PcGs) are central chromatin modifiers and repressors that have been implicated in control of embryonic stem cell (ESC) pluripotency, the precise mechanism of PcG complex recruitment remains elusive, especially in mammals. We now report that the first and second MBT repeats of L3mbtl2 are important structural and functional features that are necessary and sufficient for L3mbtl2-mediated recruitment of PRC1.6 complex to target promoters. Interestingly, this region of L3mbtl2 harbors the evolutionarily conserved Pho-binding pocket also present in Drosophila Sfmbt, and mutation of the critical residues within this pocket completely abolishes its interaction with target promoters...
March 13, 2018: Cell Reports
Ezequiel Nazer, Ryan K Dale, Madoka Chinen, Behram Radmanesh, Elissa P Lei
Drosophila Argonaute2 (AGO2) has been shown to regulate expression of certain loci in an RNA interference (RNAi)-independent manner, but its genome-wide function on chromatin remains unknown. Here, we identified the nuclear scaffolding protein LaminB as a novel interactor of AGO2. When either AGO2 or LaminB are depleted in Kc cells, similar transcription changes are observed genome-wide. In particular, changes in expression occur mainly in active or potentially active chromatin, both inside and outside LaminB-associated domains (LADs)...
March 12, 2018: PLoS Genetics
Chiahao Tsui, Carla Inouye, Michaella Levy, Andrew Lu, Laurence Florens, Michael P Washburn, Robert Tjian
Eukaryotic gene regulation is a complex process, often coordinated by the action of tens to hundreds of proteins. Although previous biochemical studies have identified many components of the basal machinery and various ancillary factors involved in gene regulation, numerous gene-specific regulators remain undiscovered. To comprehensively survey the proteome directing gene expression at a specific genomic locus of interest, we developed an in vitro nuclease-deficient Cas9 (dCas9)-targeted chromatin-based purification strategy, called "CLASP" (Cas9 locus-associated proteome), to identify and functionally test associated gene-regulatory factors...
March 5, 2018: Proceedings of the National Academy of Sciences of the United States of America
Quentin Szabo, Daniel Jost, Jia-Ming Chang, Diego I Cattoni, Giorgio L Papadopoulos, Boyan Bonev, Tom Sexton, Julian Gurgo, Caroline Jacquier, Marcelo Nollmann, Frédéric Bantignies, Giacomo Cavalli
Deciphering the rules of genome folding in the cell nucleus is essential to understand its functions. Recent chromosome conformation capture (Hi-C) studies have revealed that the genome is partitioned into topologically associating domains (TADs), which demarcate functional epigenetic domains defined by combinations of specific chromatin marks. However, whether TADs are true physical units in each cell nucleus or whether they reflect statistical frequencies of measured interactions within cell populations is unclear...
February 2018: Science Advances
Gabriel N Aughey, Alicia Estacio Gomez, Jamie Thomson, Hang Yin, Tony D Southall
During development eukaryotic gene expression is coordinated by dynamic changes in chromatin structure. Measurements of accessible chromatin are used extensively to identify genomic regulatory elements. Whilst chromatin landscapes of pluripotent stem cells are well characterised, chromatin accessibility changes in the development of somatic lineages are not well defined. Here we show that cell-specific chromatin accessibility data can be produced via ectopic expression of E. coli Dam methylase in vivo, without the requirement for cell-sorting (CATaDa)...
February 26, 2018: ELife
Larisa Melnikova, Margarita Kostyuchenko, Alexander Parshikov, Pavel Georgiev, Anton Golovnin
Su(Hw) belongs to the class of proteins that organize chromosome architecture and boundaries/insulators between regulatory domains. This protein contains a cluster of 12 zinc finger domains most of which are responsible for binding to three different modules in the consensus site. Su(Hw) forms a complex with CP190 and Mod(mdg4)-67.2 proteins that binds to well-known Drosophila insulators. To understand how Su(Hw) performs its activities and binds to specific sites in chromatin, we have examined the previously described su(Hw)f mutation that disrupts the 10th zinc finger (ZF10) responsible for Su(Hw) binding to the upstream module...
2018: PloS One
Ana García Del Arco, Bruce A Edgar, Sylvia Erhardt
Stem cells of the Drosophila midgut (ISCs) are the only mitotically dividing cells of the epithelium and, therefore, presumably the only epithelial cells that require functional kinetochores for microtubule spindle attachment during mitosis. The histone variant CENP-A marks centromeric chromatin as the site of kinetochore formation and spindle attachment during mitotic chromosome segregation. Here, we show that centromeric proteins distribute asymmetrically during ISC division. Whereas newly synthesized CENP-A is enriched in differentiating progeny, CENP-C is undetectable in these cells...
February 20, 2018: Cell Reports
En-Hui Li, Xin Zhao, Ce Zhang, Wei Liu
Fragile X syndrome is one of the most common forms of inherited intellectual disability. It is caused by mutations of the Fragile X mental retardation 1(FMR1) gene, resulting in either the loss or abnormal expression of the Fragile X mental retardation protein (FMRP). Recent research showed that FMRP participates in non-coding RNA pathways and plays various important roles in physiology, thereby extending our knowledge of the pathogenesis of the Fragile X syndrome. Initial studies showed that the Drosophila FMRP participates in siRNA and miRNA pathways by interacting with Dicer, Ago1 and Ago2, involved in neural activity and the fate determination of the germline stem cells...
February 20, 2018: Yi Chuan, Hereditas
Marina Yu Mazina, Elena V Kovalenko, Polina K Derevyanko, Julia V Nikolenko, Aleksey N Krasnov, Nadezhda E Vorobyeva
Transcriptional activation is often represented as a "one-step process" that involves the simultaneous recruitment of co-activator proteins, leading to a change in gene status. Using Drosophila developmental ecdysone-dependent genes as a model, we demonstrated that activation of transcription is instead a continuous process that consists of a number of steps at which different phases of transcription (initiation or elongation) are stimulated. Thorough evaluation of the behaviour of multiple transcriptional complexes during the early activation process has shown that the pathways by which activation proceeds for different genes may vary considerably, even in response to the same induction signal...
February 5, 2018: Biochimica et Biophysica Acta
Nadine Harrer, Christina E M Schindler, Linda K Bruetzel, Ignasi Forné, Johanna Ludwigsen, Axel Imhof, Martin Zacharias, Jan Lipfert, Felix Mueller-Planitz
Chromatin remodeling factors assume critical roles by regulating access to nucleosomal DNA. To determine the architecture of the Drosophila ISWI remodeling enzyme, we developed an integrative structural approach that combines protein cross-linking, mass spectrometry, small-angle X-ray scattering, and computational modeling. The resulting structural model shows the ATPase module in a resting state with both ATPase lobes twisted against each other, providing support for a conformation that was recently trapped by crystallography...
February 6, 2018: Structure
Kamel Jabbari, Peter Heger, Ranu Sharma, Thomas Wiehe
The CCCTC-binding factor (CTCF) is multi-functional, ubiquitously expressed, and highly conserved from Drosophila to human. It has important roles in transcriptional insulation and the formation of a high-dimensional chromatin structure. CTCF has a paralog called "Brother of Regulator of Imprinted Sites" (BORIS) or "CTCF-like" (CTCFL). It binds DNA at sites similar to those of CTCF. However, the expression profiles of the two proteins are quite different. We investigated the evolutionary trajectories of the two proteins after the duplication event using a phylogenomic and interactomic approach...
January 30, 2018: Life
Amel Zouaz, Céline Fernando, Yannick Perez, Claude Sardet, Eric Julien, Charlotte Grimaud
Tight cell-cycle regulation of the histone H4-K20 methyltransferase PR-Set7 is essential for the maintenance of genome integrity. In mammals, this mainly involves the interaction of PR-Set7 with the replication factor PCNA, which triggers the degradation of the enzyme by the CRL4CDT2 E3 ubiquitin ligase. PR-Set7 is also targeted by the SCFβ-TRCP ligase, but the role of this additional regulatory pathway remains unclear. Here, we show that Drosophila PR-Set7 undergoes a cell-cycle proteolytic regulation, independently of its interaction with PCNA...
January 24, 2018: Nucleic Acids Research
Ankita Singh, Debdeep Dutta, Maimuna Sali Paul, Dipti Verma, Mousumi Mutsuddi, Ashim Mukherjee
Chromatin-remodeling proteins play a profound role in the transcriptional regulation of gene expression during development. Here, we have shown that the chromodomain-containing protein Hat-trick is predominantly expressed within ----the oocyte nucleus, specifically within the heterochromatinized karyosome and that a mild expression is observed in follicle cells. Co-localization of Hat-trick with Heterochromatin Protein 1 and a Synaptonemal Complex component- C(3)G along with the diffused karyosome after hat-trick down-regulation shows the role of this protein in heterochromatin clustering and karyosome maintenance...
January 24, 2018: G3: Genes—Genomes—Genetics
Lijuan Feng, Zhen Shi, Jing Xie, Binbin Ma, Xin Chen
Tissue homeostasis depends on the ability of tissue-specific adult stem cells to maintain a balance between proliferation and differentiation, as well as ensure DNA damage repair. Here, we use the Drosophila male germline stem cell system to study how a chromatin factor, enhancer of polycomb [E(Pc)], regulates the proliferation-to-differentiation (mitosis-to-meiosis) transition and DNA damage repair. We identified two critical targets of E(Pc). First, E(Pc) represses CycB transcription, likely through modulating H4 acetylation...
January 23, 2018: Cell Death and Differentiation
Natalia Akulenko, Sergei Ryazansky, Valeriya Morgunova, Pavel A Komarov, Ivan Olovnikov, Chantal Vaury, Silke Jensen, Alla Kalmykova
Expression of transposable elements in the germline is controlled by Piwi-interacting (pi) RNAs produced by genomic loci termed piRNA clusters and associated with Rhino, a Heterochromatin Protein 1 (HP1) homolog. Previously, we have shown that transgenes containing a fragment of the I retrotransposon form de novo piRNA clusters in the Drosophila germline providing suppression of I-element activity. We noted that identical transgenes located in different genomic sites vary considerably in piRNA production and classified them as "strong" and "weak" piRNA clusters...
January 22, 2018: RNA
Nicholas Allen Kinney, Igor V Sharakhov, Alexey V Onufriev
BACKGROUND: It is well recognized that the interphase chromatin of higher eukaryotes folds into non-random configurations forming territories within the nucleus. Chromosome territories have biologically significant properties, and understanding how these properties change with time during lifetime of the cell is important. Chromosome-nuclear envelope (Chr-NE) interactions play a role in epigenetic regulation of DNA replication, repair, and transcription. However, their role in maintaining chromosome territories remains unclear...
January 22, 2018: Epigenetics & Chromatin
Sumanta Basu, Karl Kumbier, James B Brown, Bin Yu
Genomics has revolutionized biology, enabling the interrogation of whole transcriptomes, genome-wide binding sites for proteins, and many other molecular processes. However, individual genomic assays measure elements that interact in vivo as components of larger molecular machines. Understanding how these high-order interactions drive gene expression presents a substantial statistical challenge. Building on random forests (RFs) and random intersection trees (RITs) and through extensive, biologically inspired simulations, we developed the iterative random forest algorithm (iRF)...
January 19, 2018: Proceedings of the National Academy of Sciences of the United States of America
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