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Super-resolution microscopy reveals stochastic initiation of replication in Drosophila polytene chromosomes. Chromosome Res 2022; 30:361-383. [PMID: 35226231 PMCID: PMC9771856 DOI: 10.1007/s10577-021-09679-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 01/25/2023]
Abstract
Studying the probability distribution of replication initiation along a chromosome is a huge challenge. Drosophila polytene chromosomes in combination with super-resolution microscopy provide a unique opportunity for analyzing the probabilistic nature of replication initiation at the ultrastructural level. Here, we developed a method for synchronizing S-phase induction among salivary gland cells. An analysis of the replication label distribution in the first minutes of S phase and in the following hours after the induction revealed the dynamics of replication initiation. Spatial super-resolution structured illumination microscopy allowed identifying multiple discrete replication signals and to investigate the behavior of replication signals in the first minutes of the S phase at the ultrastructural level. We identified replication initiation zones where initiation occurs stochastically. These zones differ significantly in the probability of replication initiation per time unit. There are zones in which initiation occurs on most strands of the polytene chromosome in a few minutes. In other zones, the initiation on all strands takes several hours. Compact bands are free of replication initiation events, and the replication runs from outer edges to the middle, where band shapes may alter.
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2
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Maslova A, Krasikova A. FISH Going Meso-Scale: A Microscopic Search for Chromatin Domains. Front Cell Dev Biol 2021; 9:753097. [PMID: 34805161 PMCID: PMC8597843 DOI: 10.3389/fcell.2021.753097] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
The intimate relationships between genome structure and function direct efforts toward deciphering three-dimensional chromatin organization within the interphase nuclei at different genomic length scales. For decades, major insights into chromatin structure at the level of large-scale euchromatin and heterochromatin compartments, chromosome territories, and subchromosomal regions resulted from the evolution of light microscopy and fluorescence in situ hybridization. Studies of nanoscale nucleosomal chromatin organization benefited from a variety of electron microscopy techniques. Recent breakthroughs in the investigation of mesoscale chromatin structures have emerged from chromatin conformation capture methods (C-methods). Chromatin has been found to form hierarchical domains with high frequency of local interactions from loop domains to topologically associating domains and compartments. During the last decade, advances in super-resolution light microscopy made these levels of chromatin folding amenable for microscopic examination. Here we are reviewing recent developments in FISH-based approaches for detection, quantitative measurements, and validation of contact chromatin domains deduced from C-based data. We specifically focus on the design and application of Oligopaint probes, which marked the latest progress in the imaging of chromatin domains. Vivid examples of chromatin domain FISH-visualization by means of conventional, super-resolution light and electron microscopy in different model organisms are provided.
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Affiliation(s)
| | - Alla Krasikova
- Laboratory of Nuclear Structure and Dynamics, Cytology and Histology Department, Saint Petersburg State University, Saint Petersburg, Russia
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3
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Medvedeva AV, Tokmatcheva EV, Kaminskaya AN, Vasileva SA, Nikitina EA, Zhuravlev SA, Zakharov GA, Zatsepina OG, Savvateeva-Popova EV. Parent-of-origin effects on nuclear chromatin organization and behavior in a Drosophila model for Williams-Beuren Syndrome. Vavilovskii Zhurnal Genet Selektsii 2021; 25:472-485. [PMID: 34595370 PMCID: PMC8460428 DOI: 10.18699/vj21.054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 11/19/2022] Open
Abstract
Prognosis of neuropsychiatric disorders in progeny requires consideration of individual (1) parent-of-origin effects (POEs) relying on (2) the nerve cell nuclear 3D chromatin architecture and (3) impact of parent-specific miRNAs. Additionally, the shaping of cognitive phenotypes in parents depends on both learning acquisition and forgetting, or memory erasure. These processes are independent and controlled by different signal cascades: the first is cAMPdependent, the second relies on actin remodeling by small GTPase Rac1 - LIMK1 (LIM-kinase 1). Simple experimental model systems such as Drosophila help probe the causes and consequences leading to human neurocognitive pathologies. Recently, we have developed a Drosophila model for Williams-Beuren Syndrome (WBS): a mutant agnts3 of the agnostic locus (X:11AB) harboring the dlimk1 gene. The agnts3 mutation drastically increases the frequency of ectopic contacts (FEC) in specific regions of intercalary heterochromatin, suppresses learning/memory and affects locomotion. As is shown in this study, the polytene X chromosome bands in reciprocal hybrids between agnts3 and the wild type strain Berlin are heterogeneous in modes of FEC regulation depending either on maternal or paternal gene origin. Bioinformatic analysis reveals that FEC between X:11AB and the other X chromosome bands correlates with the occurrence of short (~30 bp) identical DNA fragments partly homologous to Drosophila 372-bp satellite DNA repeat. Although learning acquisition in a conditioned courtship suppression paradigm is similar in hybrids, the middle-term memory formation shows patroclinic inheritance. Seemingly, this depends on changes in miR-974 expression. Several parameters of locomotion demonstrate heterosis. Our data indicate that the agnts3 locus is capable of trans-regulating gene activity via POEs on the chromatin nuclear organization, thereby affecting behavior.
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Affiliation(s)
- A V Medvedeva
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia
| | - E V Tokmatcheva
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia
| | - A N Kaminskaya
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
| | - S A Vasileva
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia
| | - E A Nikitina
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia Herzen State Pedagogical University of Russia, St. Petersburg, Russia
| | - S A Zhuravlev
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia
| | - G A Zakharov
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia
| | - O G Zatsepina
- Engelhardt Institute of Molecular Biology of the Russian Academy of Sciences, Moscow, Russia
| | - E V Savvateeva-Popova
- Pavlov Institute of Physiology of the Russian Academy of Sciences, St. Petersburg, Russia
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4
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Zhuravlev AV, Zakharov GA, Anufrieva EV, Medvedeva AV, Nikitina EA, Savvateeva-Popova EV. Chromatin Structure and "DNA Sequence View": The Role of Satellite DNA in Ectopic Pairing of the Drosophila X Polytene Chromosome. Int J Mol Sci 2021; 22:8713. [PMID: 34445413 PMCID: PMC8395981 DOI: 10.3390/ijms22168713] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 08/11/2021] [Indexed: 11/16/2022] Open
Abstract
Chromatin 3D structure plays a crucial role in regulation of gene activity. Previous studies have envisioned spatial contact formations between chromatin domains with different epigenetic properties, protein compositions and transcription activity. This leaves specific DNA sequences that affect chromosome interactions. The Drosophila melanogaster polytene chromosomes are involved in non-allelic ectopic pairing. The mutant strain agnts3, a Drosophila model for Williams-Beuren syndrome, has an increased frequency of ectopic contacts (FEC) compared to the wild-type strain Canton-S (CS). Ectopic pairing can be mediated by some specific DNA sequences. In this study, using our Homology Segment Analysis software, we estimated the correlation between FEC and frequency of short matching DNA fragments (FMF) for all sections of the X chromosome of Drosophila CS and agnts3 strains. With fragment lengths of 50 nucleotides (nt), CS showed a specific FEC-FMF correlation for 20% of the sections involved in ectopic contacts. The correlation was unspecific in agnts3, which may indicate the alternative epigenetic mechanisms affecting FEC in the mutant strain. Most of the fragments that specifically contributed to FMF were related to 1.688 or 372-bp middle repeats. Thus, middle repetitive DNA may serve as an organizer of ectopic pairing.
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Affiliation(s)
- Aleksandr V. Zhuravlev
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (G.A.Z.); (A.V.M.); (E.A.N.); (E.V.S.-P.)
| | - Gennadii A. Zakharov
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (G.A.Z.); (A.V.M.); (E.A.N.); (E.V.S.-P.)
- EPAM Systems Inc., Saint Petersburg 197110, Russia
| | - Ekaterina V. Anufrieva
- Faculty of Biology, Herzen State Pedagogical University of Russia, 191186 Saint Petersburg, Russia;
| | - Anna V. Medvedeva
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (G.A.Z.); (A.V.M.); (E.A.N.); (E.V.S.-P.)
| | - Ekaterina A. Nikitina
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (G.A.Z.); (A.V.M.); (E.A.N.); (E.V.S.-P.)
- Faculty of Biology, Herzen State Pedagogical University of Russia, 191186 Saint Petersburg, Russia;
| | - Elena V. Savvateeva-Popova
- Pavlov Institute of Physiology, Russian Academy of Sciences, 199034 Saint Petersburg, Russia; (G.A.Z.); (A.V.M.); (E.A.N.); (E.V.S.-P.)
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5
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Loganathan R, Kim JH, Wells MB, Andrew DJ. Secrets of secretion-How studies of the Drosophila salivary gland have informed our understanding of the cellular networks underlying secretory organ form and function. Curr Top Dev Biol 2020; 143:1-36. [PMID: 33820619 DOI: 10.1016/bs.ctdb.2020.09.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Secretory organs are critical for organismal survival. Yet, the transcriptional regulatory mechanisms governing their development and maintenance remain unclear for most model secretory organs. The Drosophila embryonic salivary gland (SG) remedies this deficiency as one of the few organs wherein direct connections from the expression of the early patterning genes to cell specification to organ architecture and functional specialization can be made. Few other models of secretion can be accorded this distinction. Studies from the past three decades have made enormous strides in parsing out the roles of distinct transcription factors (TFs) that direct major steps in furnishing this secretory organ. In the first step of specifying the salivary gland, the activity of the Hox factors Sex combs reduced, Extradenticle, and Homothorax activate expression of fork head (fkh), sage, and CrebA, which code for the major suite of TFs that carry forward the task of organ building and maintenance. Then, in the second key step of building the SG, the program for cell fate maintenance and morphogenesis is deployed. Fkh maintains the secretory cell fate by regulating its own expression and that of sage and CrebA. Fkh and Sage maintain secretory cell viability by actively blocking apoptotic cell death. Fkh, along with two other TFs, Hkb and Rib, also coordinates organ morphogenesis, transforming two plates of precursor cells on the embryo surface into elongated internalized epithelial tubes. Acquisition of functional specialization, the third key step, is mediated by CrebA and Fkh working in concert with Sage and yet another TF, Sens. CrebA directly upregulates expression of all of the components of the secretory machinery as well as other genes (e.g., Xbp1) necessary for managing the physiological stress that inexorably accompanies high secretory load. Secretory cargo specificity is controlled by Sage and Sens in collaboration with Fkh. Investigations have also uncovered roles for various signaling pathways, e.g., Dpp signaling, EGF signaling, GPCR signaling, and cytoskeletal signaling, and their interactions within the gene regulatory networks that specify, build, and specialize the SG. Collectively, studies of the SG have expanded our knowledge of secretory dynamics, cell polarity, and cytoskeletal mechanics in the context of organ development and function. Notably, the embryonic SG has made the singular contribution as a model system that revealed the core function of CrebA in scaling up secretory capacity, thus, serving as the pioneer system in which the conserved roles of the mammalian Creb3/3L-family orthologues were first discovered.
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Affiliation(s)
- Rajprasad Loganathan
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Ji Hoon Kim
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Michael B Wells
- Idaho College of Osteopathic Medicine, Meridian, ID, United States
| | - Deborah J Andrew
- Department of Cell Biology, The Johns Hopkins University School of Medicine, Baltimore, MD, United States.
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AlHaj Abed J, Erceg J, Goloborodko A, Nguyen SC, McCole RB, Saylor W, Fudenberg G, Lajoie BR, Dekker J, Mirny LA, Wu CT. Highly structured homolog pairing reflects functional organization of the Drosophila genome. Nat Commun 2019; 10:4485. [PMID: 31582763 PMCID: PMC6776532 DOI: 10.1038/s41467-019-12208-3] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 08/27/2019] [Indexed: 01/14/2023] Open
Abstract
Trans-homolog interactions have been studied extensively in Drosophila, where homologs are paired in somatic cells and transvection is prevalent. Nevertheless, the detailed structure of pairing and its functional impact have not been thoroughly investigated. Accordingly, we generated a diploid cell line from divergent parents and applied haplotype-resolved Hi-C, showing that homologs pair with varying precision genome-wide, in addition to establishing trans-homolog domains and compartments. We also elucidate the structure of pairing with unprecedented detail, observing significant variation across the genome and revealing at least two forms of pairing: tight pairing, spanning contiguous small domains, and loose pairing, consisting of single larger domains. Strikingly, active genomic regions (A-type compartments, active chromatin, expressed genes) correlated with tight pairing, suggesting that pairing has a functional implication genome-wide. Finally, using RNAi and haplotype-resolved Hi-C, we show that disruption of pairing-promoting factors results in global changes in pairing, including the disruption of some interaction peaks.
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Affiliation(s)
- Jumana AlHaj Abed
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Jelena Erceg
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Anton Goloborodko
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
| | - Son C Nguyen
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
- Department of Genetics, Penn Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6145, USA
| | - Ruth B McCole
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Wren Saylor
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA
| | - Geoffrey Fudenberg
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA
- Gladstone Institutes of Data Science and Biotechnology, San Francisco, CA, 94158, USA
| | - Bryan R Lajoie
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605-0103, USA
- Illumina, San Diego, CA, USA
| | - Job Dekker
- Howard Hughes Medical Institute and Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01605-0103, USA
| | - Leonid A Mirny
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
- Department of Physics, Massachusetts Institute of Technology (MIT), Cambridge, MA, 02139, USA.
| | - C-Ting Wu
- Department of Genetics, Harvard Medical School, Boston, MA, 02115, USA.
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, 02115, USA.
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7
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Sidorenko DS, Sidorenko IA, Zykova TY, Goncharov FP, Larsson J, Zhimulev IF. Molecular and genetic organization of bands and interbands in the dot chromosome of Drosophila melanogaster. Chromosoma 2019; 128:97-117. [PMID: 31041520 PMCID: PMC6536484 DOI: 10.1007/s00412-019-00703-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 01/09/2019] [Accepted: 04/02/2019] [Indexed: 12/24/2022]
Abstract
The fourth chromosome smallest in the genome of Drosophila melanogaster differs from other chromosomes in many ways. It has high repeat density in conditions of a large number of active genes. Gray bands represent a significant part of this polytene chromosome. Specific proteins including HP1a, POF, and dSETDB1 establish the epigenetic state of this unique chromatin domain. In order to compare maps of localization of genes, bands, and chromatin types of the fourth chromosome, we performed FISH analysis of 38 probes chosen according to the model of four chromatin types. It allowed clarifying the dot chromosome cytological map consisting of 16 loose gray bands, 11 dense black bands, and 26 interbands. We described the relation between chromatin states and bands. Open aquamarine chromatin mostly corresponds to interbands and it contains 5'UTRs of housekeeping genes. Their coding parts are embedded in gray bands substantially composed of lazurite chromatin of intermediate compaction. Polygenic black bands contain most of dense ruby chromatin, and also some malachite and lazurite. Having an accurate map of the fourth chromosome bands and its correspondence to physical map, we found that DNase I hypersensitivity sites, ORC2 protein, and P-elements are mainly located in open aquamarine chromatin, while element 1360, characteristic of the fourth chromosome, occupies band chromatin types. POF and HP1a proteins providing special organization of this chromosome are mostly located in aquamarine and lazurite chromatin. In general, band organization of the fourth chromosome shares the features of the whole Drosophila genome.
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Affiliation(s)
- Darya S Sidorenko
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090
| | - Ivan A Sidorenko
- Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
| | - Tatyana Yu Zykova
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090
| | - Fedor P Goncharov
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090
| | - Jan Larsson
- Department of Molecular Biology, Umeå University, Umeå, Sweden
| | - Igor F Zhimulev
- Institute of Molecular and Cellular Biology of the Siberian Branch of the Russian Academy of Sciences, Lavrentiev Ave. 8/2, Novosibirsk, Russia, 630090. .,Laboratory of structural, functional and comparative genomics of the Novosibirsk State University, Novosibirsk, Russia.
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8
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Schaeffer SW. Muller "Elements" in Drosophila: How the Search for the Genetic Basis for Speciation Led to the Birth of Comparative Genomics. Genetics 2018; 210:3-13. [PMID: 30166445 PMCID: PMC6116959 DOI: 10.1534/genetics.118.301084] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 04/30/2018] [Indexed: 12/22/2022] Open
Abstract
The concept of synteny, or conservation of genes on the same chromosome, traces its origins to the early days of Drosophila genetics. This discovery emerged from comparisons of linkage maps from different species of Drosophila with the goal of understanding the process of speciation. H. J. Muller published a landmark article entitled Bearings of the "Drosophila" work on systematics, where he synthesized genetic and physical map data and proposed a model of speciation and chromosomal gene content conservation. These models have withstood the test of time with the advent of molecular genetic analysis from protein to genome level variation. Muller's ideas provide a framework to begin to answer questions about the evolutionary forces that shape the structure of the genome.
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Affiliation(s)
- Stephen W Schaeffer
- Department of Biology, The Pennsylvania State University, State College, Pennsylvania 16802-5301
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9
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Razin SV. Structural-Functional Organization of the Eukaryotic Cell Nucleus and Transcription Regulation: Introduction to This Special Issue of Biochemistry (Moscow). BIOCHEMISTRY (MOSCOW) 2018; 83:299-301. [PMID: 29626917 DOI: 10.1134/s0006297918040016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This issue of Biochemistry (Moscow) is devoted to the cell nucleus and mechanisms of transcription regulation. Over the years, biochemical processes in the cell nucleus have been studied in isolation, outside the context of their spatial organization. Now it is clear that segregation of functional processes within a compartmentalized cell nucleus is very important for the implementation of basic genetic processes. The functional compartmentalization of the cell nucleus is closely related to the spatial organization of the genome, which in turn plays a key role in the operation of epigenetic mechanisms. In this issue of Biochemistry (Moscow), we present a selection of review articles covering the functional architecture of the eukaryotic cell nucleus, the mechanisms of genome folding, the role of stochastic processes in establishing 3D architecture of the genome, and the impact of genome spatial organization on transcription regulation.
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Affiliation(s)
- S V Razin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia
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