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https://www.readbyqxmd.com/read/28640690/a-new-layer-of-rrna-regulation-by-small-interference-rnas-and-the-nuclear-rnai-pathway
#1
Xufei Zhou, Xiangyang Chen, Yun Wang, Xuezhu Feng, Shouhong Guang
Ribosome biogenesis drives cell growth and proliferation, but mechanisms that modulate this process remain poorly understood. For a long time, small ribosomal RNA sequences have been widely treated as non-specific degradation products and neglected as garbage sequences. Recently, we identified a new class of antisense ribosomal siRNAs (risiRNAs) that downregulate pre-rRNA through the nuclear RNAi pathway in C. elegans. risiRNAs exhibit sequence characteristics similar to 22G RNA while complement to 18S and 26S rRNA...
June 22, 2017: RNA Biology
https://www.readbyqxmd.com/read/28637749/cell-cycle-dependent-spatial-segregation-of-telomerase-from-sites-of-dna-damage
#2
Faissal Ouenzar, Maxime Lalonde, Hadrien Laprade, Geneviève Morin, Franck Gallardo, Samuel Tremblay-Belzile, Pascal Chartrand
Telomerase can generate a novel telomere at DNA double-strand breaks (DSBs), an event called de novo telomere addition. How this activity is suppressed remains unclear. Combining single-molecule imaging and deep sequencing, we show that the budding yeast telomerase RNA (TLC1 RNA) is spatially segregated to the nucleolus and excluded from sites of DNA repair in a cell cycle-dependent manner. Although TLC1 RNA accumulates in the nucleoplasm in G1/S, Pif1 activity promotes TLC1 RNA localization in the nucleolus in G2/M...
June 21, 2017: Journal of Cell Biology
https://www.readbyqxmd.com/read/28636660/cellular-sensitivity-to-uv-irradiation-is-mediated-by-rna-polymerase-i-transcription
#3
Robin Assfalg, Marius Costel Alupei, Maximilian Wagner, Sylvia Koch, Omar Garcia Gonzalez, Adrian Schelling, Karin Scharffetter-Kochanek, Sebastian Iben
The nucleolus has long been considered to be a pure ribosome factory. However, over the last two decades it became clear that the nucleolus is involved in numerous other functions besides ribosome biogenesis. Our experiments indicate that the activity of RNA polymerase I (Pol I) transcription monitors the integrity of the DNA and influences the response to nucleolar stress as well as the rate of survival. Cells with a repressed ribosomal DNA (rDNA) transcription activity showed an increased and prolonged p53 stabilisation after UVC-irradiation...
2017: PloS One
https://www.readbyqxmd.com/read/28634865/dynamics-of-tobacco-dna-topoisomerases-ii-in-cell-cycle-regulation-to-manage-topological-constrains-during-replication-transcription-and-mitotic-chromosome-condensation-and-segregation
#4
Badri Nath Singh, V Mohan Murali Achary, Varakumar Panditi, Sudhir K Sopory, Malireddy K Reddy
The topoisomerase II expression varies as a function of cell proliferation. Maximal topoisomerase II expression was tightly coupled to S phase and G2/M phase via both transcriptional and post-transcriptional regulation. Investigation in meiosis using pollen mother cells also revealed that it is not the major component of meiotic chromosomes, it seems to diffuse out once meiotic chromosomal condensation is completed. Synchronized tobacco BY-2 cell cultures were used to study the role of topoisomerase II in various stages of the cell cycle...
June 20, 2017: Plant Molecular Biology
https://www.readbyqxmd.com/read/28629776/unveiling-the-non-repair-face-of-the-base-excision-repair-pathway-in-rna-processing-a-missing-link-between-dna-repair-and-gene-expression
#5
REVIEW
Giulia Antoniali, Matilde Clarissa Malfatti, Gianluca Tell
The Base Excision Repair (BER) pathway, initially studied as a mere DNA repair pathway, has been later found to be implicated in the expression of cancer related genes in human. For several years, this intricate involvement in apparently different processes represented a mystery, which we now are starting to unveil. The BER handles simple alkylation and oxidative lesions arising from both endogenous and exogenous sources, including cancer therapy agents. Surprisingly, BER pathway involvement in transcriptional regulation, immunoglobulin variability and switch recombination, RNA metabolism and nucleolar function is astonishingly consolidating...
June 9, 2017: DNA Repair
https://www.readbyqxmd.com/read/28623274/reduction-in-chromosome-mobility-accompanies-nuclear-organization-during-early-embryogenesis-in-caenorhabditis-elegans
#6
Ritsuko Arai, Takeshi Sugawara, Yuko Sato, Yohei Minakuchi, Atsushi Toyoda, Kentaro Nabeshima, Hiroshi Kimura, Akatsuki Kimura
In differentiated cells, chromosomes are packed inside the cell nucleus in an organised fashion. In contrast, little is known about how chromosomes are packed in undifferentiated cells and how nuclear organization changes during development. To assess changes in nuclear organization during the earliest stages of development, we quantified the mobility of a pair of homologous chromosomal loci in the interphase nuclei of Caenorhabditis elegans embryos. The distribution of distances between homologous loci was consistent with a random distribution up to the 8-cell stage but not at later stages...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28622108/fluctuations-of-pol-i-and-fibrillarin-contents-of-the-nucleoli
#7
M Hornáček, L Kováčik, T Mazel, D Cmarko, E Bártová, I Raška, E Smirnov
Nucleoli are formed on the basis of ribosomal DNA (rDNA) clusters called Nucleolus Organizer Regions (NORs). Each NOR contains multiple genes coding for RNAs of the ribosomal particles. The prominent components of the nucleolar ultrastructure, fibrillar centers (FC) and dense fibrillar components (DFC), together compose FC/DFC units. These units are centers of rDNA transcription by RNA polymerase I (pol I), as well as the early processing events, in which an essential role belongs to fibrillarin. Each FC/DFC unit probably corresponds to a single transcriptionally active gene...
June 16, 2017: Nucleus
https://www.readbyqxmd.com/read/28611663/epigenetic-modifications-to-h3k9-in-renal-tubulointerstitial-cells-after-unilateral-ureteric-obstruction-and-tgf-%C3%AE-1-stimulation
#8
Timothy D Hewitson, Stephen G Holt, Sven-Jean Tan, Belinda Wigg, Chrishan S Samuel, Edward R Smith
Introduction: Epigenetic regulation of fibrogenesis through post-translational histone modifications (marks) may be a key determinant of progression in renal disease. In this study, we examined the distribution and acquisition of histone 3 Lysine 9 (H3K9) marks after injury and stimulation with the pro-fibrotic cytokine TGF-β1. Our focus was on their presence in activated fibroblasts (myofibroblasts) and epithelial cells (epithelial-mesenchymal transition). Methods and Results: Immunofluorescent microscopy was used to examine global H3K9 acetylation (H3K9Ac) and tri-methylation (H3K9Me3) after unilateral ureteric obstruction (UUO) in mice...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28609676/hepatocellular-differentiation-status-is-characterized-by-distinct-subnuclear-localization-and-form-of-the-chanzyme-trpm7
#9
Adenike Ogunrinde, Robyn D Pereira, Natalie Beaton, D Hung Lam, Christiane Whetstone, Ceredwyn E Hill
The channel-kinase TRPM7 is important for the survival, proliferation, and differentiation, of many cell types. Both plasma membrane channel activity and kinase function are implicated in these roles. Channel activity is greater in less differentiated hepatoma cells compared with non-dividing, terminally differentiated adult hepatocytes, suggesting differences in protein expression and/or localization. We used electrophysiological and immunofluorescence approaches to establish whether hepatocellular differentiation is associated with altered TRPM7 expression...
June 10, 2017: Differentiation; Research in Biological Diversity
https://www.readbyqxmd.com/read/28601145/ovarian-development-and-the-reproductive-profile-of-astyanax-altiparanae-teleostei-characidae-over-one-year-applications-in-fish-farming
#10
Mônica Cassel, Chayrra Chehade, Giovana Souza Branco, Danilo Caneppele, Elizabeth Romagosa, Maria Inês Borella
Astyanax altiparanae is a Brazilian species of substantial commercial, environmental and scientific importance; however, existing studies on its reproduction do not seem to provide enough details. In light of the increasing use of this species in fish farming and the need for basic studies for the development of new production technologies, we describe the structural and ultrastructural characteristics of the ovaries of A. altiparanae, and characterize the species' reproductive cycle. Females were collected monthly from March 2013 to February 2014, and reproductive management began in October 2013...
August 2017: Theriogenology
https://www.readbyqxmd.com/read/28600324/reconstitution-of-the-oocyte-nucleolus-in-mice-by-a-single-nucleolar-protein-npm2
#11
Sugako Ogushi, Kazuo Yamagata, Chikashi Obuse, Keiko Furuta, Teruhiko Wakayama, Martin M Matzuk, Mitinori Saitou
The mammalian oocyte nucleolus, the most prominent subcellular organelle in the oocyte, is vital in early development, yet its key functions and constituents remain unclear. We show here that the parthenotes/zygotes derived from enucleolated oocytes exhibited abnormal heterochromatin formation around parental peri-centromeric DNAs, which led to a significant mitotic delay and frequent chromosome mis-segregation upon the first mitotic division. A proteomic analysis identified NPM2 as a dominant component of the oocyte nucleolus...
June 9, 2017: Journal of Cell Science
https://www.readbyqxmd.com/read/28597848/effects-of-soft-interactions-and-bound-mobility-on-diffusion-in-crowded-environments-a-model-of-sticky-and-slippery-obstacles
#12
Michael Stefferson, Samantha Norris, Franck Vernery, Meredith D Betterton, Loren Hough
Crowded environments modify the diffusion of macromolecules, generally slowing their movement and inducing transient anomalous subdiffusion. The presence of obstacles also modifies the kinetics and equilibrium behavior of tracers. While previous theoretical studies of particle diffusion have typically assumed either impenetrable obstacles or binding interactions that immobilize the particle, in many cellular contexts bound particles remain mobile. Examples include membrane proteins with some entry and diffusion within lipid domains, and proteins that can enter into non-membrane bound compartments such as the nucleolus...
June 9, 2017: Physical Biology
https://www.readbyqxmd.com/read/28588079/focal-accumulation-of-preribosomes-outside-the-nucleolus-during-metaphase-anaphase-in-budding-yeast
#13
Giulia Moriggi, Sonia G Gaspar, Blanca Nieto, Xosé R Bustelo, Mercedes Dosil
Saccharomyces cerevisiae contains one nucleolus that remains intact in the mother-cell side of the nucleus throughout most of mitosis. Based on this, it is assumed that the bulk of ribosome production during cell division occurs in the mother cell. Here, we show that the ribosome synthesis machinery localizes not only in the nucleolus but also at a center that is present in the bud side of the nucleus after the initiation of mitosis. This center can be visualized by live microscopy as a punctate body located in close proximity to the nuclear envelope and opposite to the nucleolus...
June 6, 2017: RNA
https://www.readbyqxmd.com/read/28582471/sumo-regulates-p21cip1-intracellular-distribution-and-with-p21cip1-facilitates-multiprotein-complex-formation-in-the-nucleolus-upon-dna-damage
#14
Sonia Brun, Neus Abella, Maria T Berciano, Olga Tapia, Montserrat Jaumot, Raimundo Freire, Miguel Lafarga, Neus Agell
We previously showed that p21Cip1 transits through the nucleolus on its way from the nucleus to the cytoplasm and that DNA damage inhibits this transit and induces the formation of p21Cip1-containing intranucleolar bodies (INoBs). Here, we demonstrate that these INoBs also contain SUMO-1 and UBC9, the E2 SUMO-conjugating enzyme. Furthermore, whereas wild type SUMO-1 localized in INoBs, a SUMO-1 mutant, which is unable to conjugate with proteins, does not, suggesting the presence of SUMOylated proteins at INoBs...
2017: PloS One
https://www.readbyqxmd.com/read/28579196/a-puzzle-of-life-crafting-ribosomal-subunits
#15
REVIEW
Dieter Kressler, Ed Hurt, Jochen Baßler
The biogenesis of eukaryotic ribosomes is a complicated process during which the transcription, modification, folding, and processing of the rRNA is coupled with the ordered assembly of ∼80 ribosomal proteins (r-proteins). Ribosome synthesis is catalyzed and coordinated by more than 200 biogenesis factors as the preribosomal subunits acquire maturity on their path from the nucleolus to the cytoplasm. Several biogenesis factors also interconnect the progression of ribosome assembly with quality control of important domains, ensuring that only functional subunits engage in translation...
June 1, 2017: Trends in Biochemical Sciences
https://www.readbyqxmd.com/read/28575119/nucleolus-association-of-chromosomal-domains-is-largely-maintained-in-cellular-senescence-despite-massive-nuclear-reorganisation
#16
Stefan Dillinger, Tobias Straub, Attila Németh
Mammalian chromosomes are organized in structural and functional domains of 0.1-10 Mb, which are characterized by high self-association frequencies in the nuclear space and different contact probabilities with nuclear sub-compartments. They exhibit distinct chromatin modification patterns, gene expression levels and replication timing. Recently, nucleolus-associated chromosomal domains (NADs) have been discovered, yet their precise genomic organization and dynamics are still largely unknown. Here, we use nucleolus genomics and single-cell experiments to address these questions in human embryonic fibroblasts during replicative senescence...
2017: PloS One
https://www.readbyqxmd.com/read/28566085/prevalence-of-autoantibodies-against-cellular-antigens-in-patients-with-hiv-and-leprosy-coinfection-in-the-amazon-region
#17
Clea Nazaré Carneiro Bichara, Carlos David Araújo Bichara, Camila Tostes, Marinete Marins Povoa, Juarez Antonio Simões Quaresma, Marília Brasil Xavier
BACKGROUND: Infectious agents can activate self-reactive T cells. In general, infections trigger various mechanisms, including a lack of auto-tolerance, induction of costimulatory molecules on antigen presenting cells, and molecular simulation, in addition to cross-reactions between microbial antigens and self-antigens. HIV and leprosy coinfections lead to self-immunity with the production of autoantibodies. However, not enough data on the immune behaviour associated with this coinfection are available...
June 1, 2017: Infectious Diseases of Poverty
https://www.readbyqxmd.com/read/28544883/the-limiting-pool-mechanism-fails-to-control-the-size-of-multiple-organelles
#18
Lishibanya Mohapatra, Thibaut J Lagny, David Harbage, Predrag R Jelenkovic, Jane Kondev
How the size of micrometer-scale cellular structures such as the mitotic spindle, cytoskeletal filaments, the nucleus, the nucleolus, and other non-membrane bound organelles is controlled despite a constant turnover of their constituent parts is a central problem in biology. Experiments have implicated the limiting-pool mechanism: structures grow by stochastic addition of molecular subunits from a finite pool until the rates of subunit addition and removal are balanced, producing a structure of well-defined size...
May 24, 2017: Cell Systems
https://www.readbyqxmd.com/read/28512234/a-guide-for-targeted-sumo-removal
#19
REVIEW
Nalini Dhingra, Xiaolan Zhao
SUMO homeostasis is important for many cellular processes. In the current issue of Genes & Development, Liang and colleagues (pp. 802-815) demonstrate how a desumoylation enzyme is targeted to the nucleolus for removing SUMO from specific substrates and how curtailing sumoylation levels can regulate transcription in this nuclear compartment.
April 15, 2017: Genes & Development
https://www.readbyqxmd.com/read/28502309/effects-of-vitrification-of-cumulus-enclosed-porcine-oocytes-at-the-germinal-vesicle-stage-on-cumulus-expansion-nuclear-progression-and-cytoplasmic-maturation
#20
Ruth Appeltant, Tamás Somfai, Elisa C S Santos, Thanh Quang Dang-Nguyen, Takashi Nagai, Kazuhiro Kikuchi
Although offspring have been produced from porcine oocytes vitrified at the germinal vesicle (GV) stage, the rate of embryo development remains low. In the present study, nuclear morphology and progression, cumulus expansion, transzonal projections (TZPs), ATP and glutathione (GSH) levels were compared between vitrified cumulus-oocyte complexes (COCs) and control COCs (no cryoprotectant treatment and no cooling), as well as a toxicity control (no cooling). Vitrification was performed with 17.5% (v/v) ethylene glycol and 17...
May 15, 2017: Reproduction, Fertility, and Development
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