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Amiad-Pavlov D, Lorber D, Bajpai G, Reuveny A, Roncato F, Alon R, Safran S, Volk T. Live imaging of chromatin distribution reveals novel principles of nuclear architecture and chromatin compartmentalization. SCIENCE ADVANCES 2021; 7:7/23/eabf6251. [PMID: 34078602 PMCID: PMC8172175 DOI: 10.1126/sciadv.abf6251] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Accepted: 04/15/2021] [Indexed: 05/12/2023]
Abstract
Live imaging of chromatin in an intact organism reveals a novel mode of mesoscale chromatin organization at nuclear periphery.
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Affiliation(s)
- Daria Amiad-Pavlov
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Dana Lorber
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Gaurav Bajpai
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Adriana Reuveny
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Francesco Roncato
- Department of Immunology Weizmann Institute of Science, Rehovot, Israel
| | - Ronen Alon
- Department of Immunology Weizmann Institute of Science, Rehovot, Israel
| | - Samuel Safran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Talila Volk
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
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2
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Bondarenko SM, Sharakhov IV. Reorganization of the nuclear architecture in the Drosophila melanogaster Lamin B mutant lacking the CaaX box. Nucleus 2021; 11:283-298. [PMID: 32960740 PMCID: PMC7529411 DOI: 10.1080/19491034.2020.1819704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Lamins interact with the nuclear membrane and chromatin but the precise players and mechanisms of these interactions are unknown. Here, we tested whether the removal of the CaaX motif from Lamin B disrupts its attachment to the nuclear membrane and affects chromatin distribution. We used Drosophila melanogaster LamA25 homozygous mutants that lack the CaaX box. We found that the mutant Lamin B was not confined to the nuclear periphery but was distributed throughout the nuclear interior, colocalizing with chromosomes in salivary gland and proventriculus. The peripheral position of Lamin C, nuclear pore complex (NPC), heterochromatin protein 1a (HP1a), H3K9me2- and H3K27me3-associated chromatin remained intact. The fluorescence intensity of the DAPI-stained peripheral chromatin significantly decreased and that of the central chromatin significantly increased in the proventriculus nuclei of the mutantflies compared to wild-type. However, the mutation had little effect on chromatin radial distribution inside highly polytenized salivary gland nuclei.
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Affiliation(s)
- Semen M Bondarenko
- Department of Entomology, Virginia Polytechnic Institute and State University , Blacksburg, Virginia, USA.,Department of Cytology and Genetics, Tomsk State University , Tomsk, Russian Federation
| | - Igor V Sharakhov
- Department of Entomology, Virginia Polytechnic Institute and State University , Blacksburg, Virginia, USA
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3
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Kinney N, Hickman M, Anandakrishnan R, Garner HR. Crossing complexity of space-filling curves reveals entanglement of S-phase DNA. PLoS One 2020; 15:e0238322. [PMID: 32866178 PMCID: PMC7458320 DOI: 10.1371/journal.pone.0238322] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 08/13/2020] [Indexed: 01/26/2023] Open
Abstract
Space-filling curves have been used for decades to study the folding principles of globular proteins, compact polymers, and chromatin. Formally, space-filling curves trace a single circuit through a set of points (x,y,z); informally, they correspond to a polymer melt. Although not quite a melt, the folding principles of Human chromatin are likened to the Hilbert curve: a type of space-filling curve. Hilbert-like curves in general make biologically compelling models of chromatin; in particular, they lack knots which facilitates chromatin folding, unfolding, and easy access to genes. Knot complexity has been intensely studied with the aid of Alexander polynomials; however, the approach does not generalize well to cases of more than one chromosome. Crossing complexity is an understudied alternative better suited for quantifying entanglement between chromosomes. Do Hilbert-like configurations limit crossing complexity between chromosomes? How does crossing complexity for Hilbert-like configurations compare to equilibrium configurations? To address these questions, we extend the Mansfield algorithm to enable sampling of Hilbert-like space filling curves on a simple cubic lattice. We use the extended algorithm to generate equilibrium, intermediate, and Hilbert-like configurational ensembles and compute crossing complexity between curves (chromosomes) in each configurational snapshot. Our main results are twofold: (a) Hilbert-like configurations limit entanglement between chromosomes and (b) Hilbert-like configurations do not limit entanglement in a model of S-phase DNA. Our second result is particularly surprising yet easily rationalized with a geometric argument. We explore ergodicity of the extended algorithm and discuss our results in the context of more sophisticated models of chromatin.
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Affiliation(s)
- Nick Kinney
- Edward Via College of Osteopathic Medicine, Blacksburg, VA, United States of America
- Gibbs Cancer Center & Research Institute, Spartanburg, SC, United States of America
| | - Molly Hickman
- Department of Computer Science, Virginia Tech, Blacksburg, VA, United States of America
| | - Ramu Anandakrishnan
- Edward Via College of Osteopathic Medicine, Blacksburg, VA, United States of America
- Gibbs Cancer Center & Research Institute, Spartanburg, SC, United States of America
| | - Harold R. Garner
- Edward Via College of Osteopathic Medicine, Blacksburg, VA, United States of America
- Gibbs Cancer Center & Research Institute, Spartanburg, SC, United States of America
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4
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Compton A, Sharakhov IV, Tu Z. Recent advances and future perspectives in vector-omics. CURRENT OPINION IN INSECT SCIENCE 2020; 40:94-103. [PMID: 32650287 PMCID: PMC8041138 DOI: 10.1016/j.cois.2020.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 05/07/2020] [Accepted: 05/18/2020] [Indexed: 06/11/2023]
Abstract
We have reviewed recent progress and the remaining challenges in vector-omics. We have highlighted several technologies and applications that facilitate novel biological insights beyond achieving a reference-quality genome assembly. Among other topics, we have discussed the applications of chromatin conformation capture, chromatin accessibility assays, optical mapping, full-length RNA sequencing, single cell RNA analysis, proteomics, and population genomics. We anticipate that we will witness a great expansion in vector-omics research not only in its application in a broad range of species, but also its ability to uncover novel genetic elements and tackle previously inaccessible regions of the genome. It is our hope that the continued innovation in device portability, cost reduction, and informatics support will in the foreseeable future bring vector-omics to every vector laboratory and field station in the world, which will have an unparalleled impact on basic research and the control of vector-borne infectious diseases.
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Affiliation(s)
- Austin Compton
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, United States
| | - Igor V Sharakhov
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, United States; Department of Entomology, Virginia Tech, Blacksburg, VA 24061, United States; The Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, VA 24061, United States; Department of Genetics and Cell Biology, Tomsk State University, Tomsk 634050, Russia
| | - Zhijian Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States; Department of Entomology, Virginia Tech, Blacksburg, VA 24061, United States; The Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Tech, Blacksburg, VA 24061, United States.
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5
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George P, Kinney NA, Liang J, Onufriev AV, Sharakhov IV. Three-dimensional Organization of Polytene Chromosomes in Somatic and Germline Tissues of Malaria Mosquitoes. Cells 2020; 9:cells9020339. [PMID: 32024176 PMCID: PMC7072178 DOI: 10.3390/cells9020339] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/22/2020] [Accepted: 01/28/2020] [Indexed: 12/17/2022] Open
Abstract
Spatial organization of chromosome territories and interactions between interphase chromosomes themselves, as well as with the nuclear periphery, play important roles in epigenetic regulation of the genome function. However, the interplay between inter-chromosomal contacts and chromosome-nuclear envelope attachments in an organism’s development is not well-understood. To address this question, we conducted microscopic analyses of the three-dimensional chromosome organization in malaria mosquitoes. We employed multi-colored oligonucleotide painting probes, spaced 1 Mb apart along the euchromatin, to quantitatively study chromosome territories in larval salivary gland cells and adult ovarian nurse cells of Anopheles gambiae, An. coluzzii, and An. merus. We found that the X chromosome territory has a significantly smaller volume and is more compact than the autosomal arm territories. The number of inter-chromosomal, and the percentage of the chromosome–nuclear envelope, contacts were conserved among the species within the same cell type. However, the percentage of chromosome regions located at the nuclear periphery was typically higher, while the number of inter-chromosomal contacts was lower, in salivary gland cells than in ovarian nurse cells. The inverse correlation was considerably stronger for the autosomes. Consistent with previous theoretical arguments, our data indicate that, at the genome-wide level, there is an inverse relationship between chromosome-nuclear envelope attachments and chromosome–chromosome interactions, which is a key feature of the cell type-specific nuclear architecture.
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Affiliation(s)
- Phillip George
- Department of Entomology, Virginia Tech, Blacksburg, VA 24061, USA; (P.G.); (J.L.)
| | - Nicholas A. Kinney
- Genomics, Bioinformatics and Computational Biology, Virginia Tech, Blacksburg, VA 24061, USA; (N.A.K.); (A.V.O.)
| | - Jiangtao Liang
- Department of Entomology, Virginia Tech, Blacksburg, VA 24061, USA; (P.G.); (J.L.)
| | - Alexey V. Onufriev
- Genomics, Bioinformatics and Computational Biology, Virginia Tech, Blacksburg, VA 24061, USA; (N.A.K.); (A.V.O.)
- Department of Computer Science, Virginia Tech, Blacksburg, VA 24061, USA
| | - Igor V. Sharakhov
- Department of Entomology, Virginia Tech, Blacksburg, VA 24061, USA; (P.G.); (J.L.)
- Genomics, Bioinformatics and Computational Biology, Virginia Tech, Blacksburg, VA 24061, USA; (N.A.K.); (A.V.O.)
- Department of Cytology and Genetics, Tomsk State University, 634050 Tomsk, Russian Federation
- Correspondence: ; Tel.: +1-540-231-7316
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6
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Perez-Rathke A, Sun Q, Wang B, Boeva V, Shao Z, Liang J. CHROMATIX: computing the functional landscape of many-body chromatin interactions in transcriptionally active loci from deconvolved single cells. Genome Biol 2020; 21:13. [PMID: 31948478 PMCID: PMC6966897 DOI: 10.1186/s13059-019-1904-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Accepted: 11/27/2019] [Indexed: 02/06/2023] Open
Abstract
Chromatin interactions are important for gene regulation and cellular specialization. Emerging evidence suggests many-body spatial interactions play important roles in condensing super-enhancer regions into a cohesive transcriptional apparatus. Chromosome conformation studies using Hi-C are limited to pairwise, population-averaged interactions; therefore unsuitable for direct assessment of many-body interactions. We describe a computational model, CHROMATIX, which reconstructs ensembles of single-cell chromatin structures by deconvolving Hi-C data and identifies significant many-body interactions. For a diverse set of highly active transcriptional loci with at least 2 super-enhancers, we detail the many-body functional landscape and show DNase accessibility, POLR2A binding, and decreased H3K27me3 are predictive of interaction-enriched regions.
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Affiliation(s)
- Alan Perez-Rathke
- Richard and Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago, IL USA
| | - Qiu Sun
- Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai, China
| | - Boshen Wang
- Richard and Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago, IL USA
| | - Valentina Boeva
- Institut Cochin, INSERM U1016, CNRS UMR 8104, Paris Descartes University UMR-S1016, Paris, 75014 France
- Department of Computer Science, ETH Zurich, Zürich, Switzerland
| | - Zhifeng Shao
- State Key Laboratory for Oncogenes and Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Jie Liang
- Richard and Loan Hill Department of Bioengineering, University of Illinois at Chicago, Chicago, IL USA
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7
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Dialynas G, Delabaere L, Chiolo I. Arp2/3 and Unc45 maintain heterochromatin stability in Drosophila polytene chromosomes. Exp Biol Med (Maywood) 2019; 244:1362-1371. [PMID: 31364400 PMCID: PMC6880141 DOI: 10.1177/1535370219862282] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/18/2019] [Indexed: 12/31/2022] Open
Abstract
Repairing DNA double-strand breaks is particularly challenging in pericentromeric heterochromatin, where the abundance of repeated sequences exacerbates the risk of ectopic recombination. In Drosophila Kc cells, accurate homologous recombination repair of heterochromatic double-strand breaks relies on the relocalization of repair sites to the nuclear periphery before Rad51 recruitment and strand invasion. This movement is driven by Arp2/3-dependent nuclear actin filaments and myosins’ ability to walk along them. Conserved mechanisms enable the relocalization of heterochromatic repair sites in mouse cells, and defects in these pathways lead to massive ectopic recombination in heterochromatin and chromosome rearrangements. In Drosophila polytene chromosomes, extensive DNA movement is blocked by a stiff structure of chromosome bundles. Repair pathways in this context are poorly characterized, and whether heterochromatic double-strand breaks relocalize in these cells is unknown. Here, we show that damage in heterochromatin results in relaxation of the heterochromatic chromocenter, consistent with a dynamic response. Arp2/3, the Arp2/3 activator Scar, and the myosin activator Unc45, are required for heterochromatin stability in polytene cells, suggesting that relocalization enables heterochromatin repair also in this tissue. Together, these studies reveal critical roles for actin polymerization and myosin motors in heterochromatin repair and genome stability across different organisms and tissue types.
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Affiliation(s)
- George Dialynas
- Department of Molecular and Computational Biology,
University
of Southern California, Los Angeles
90089, USA
| | - Laetitia Delabaere
- Department of Molecular and Computational Biology,
University
of Southern California, Los Angeles
90089, USA
| | - Irene Chiolo
- Department of Molecular and Computational Biology,
University
of Southern California, Los Angeles
90089, USA
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Sharakhov IV, Bondarenko SM, Artemov GN, Onufriev AV. The Role of Chromosome–Nuclear Envelope Attachments in 3D Genome Organization. BIOCHEMISTRY (MOSCOW) 2018; 83:350-358. [DOI: 10.1134/s0006297918040065] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Kinney NA, Sharakhov IV, Onufriev AV. Chromosome-nuclear envelope attachments affect interphase chromosome territories and entanglement. Epigenetics Chromatin 2018; 11:3. [PMID: 29357905 PMCID: PMC5776839 DOI: 10.1186/s13072-018-0173-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Accepted: 01/08/2018] [Indexed: 02/07/2023] Open
Abstract
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. Results We use coarse-grained molecular dynamics simulations to study the effects of Chr–NE interactions on the dynamics of chromosomes within a model of the Drosophila melanogaster regular (non-polytene) interphase nucleus, on timescales comparable to the duration of interphase. The model simulates the dynamics of chromosomes bounded by the NE. Initially, the chromosomes in the model are prearranged in fractal-like configurations with physical parameters such as nucleus size and chromosome persistence length taken directly from experiment. Time evolution of several key observables that characterize the chromosomes is quantified during each simulation: chromosome territories, chromosome entanglement, compactness, and presence of the Rabl (polarized) chromosome arrangement. We find that Chr–NE interactions help maintain chromosome territories by slowing down and limiting, but not eliminating, chromosome entanglement on biologically relevant timescales. At the same time, Chr–NE interactions have little effect on the Rabl chromosome arrangement as well as on how chromosome compactness changes with time. These results are rationalized by simple dimensionality arguments, robust to model details. All results are robust to the simulated activity of topoisomerase, which may be present in the interphase cell nucleus. Conclusions Our study demonstrates that Chr–NE attachments may help maintain chromosome territories, while slowing down and limiting chromosome entanglement on biologically relevant timescales. However, Chr–NE attachments have little effect on chromosome compactness or the Rabl chromosome arrangement. Electronic supplementary material The online version of this article (10.1186/s13072-018-0173-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Nicholas Allen Kinney
- Genomics Bioinformatics and Computational Biology, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Igor V Sharakhov
- Genomics Bioinformatics and Computational Biology, Virginia Tech, Blacksburg, VA, 24061, USA. .,Department of Entomology, Virginia Tech, Blacksburg, VA, 24061, USA. .,Laboratory of Ecology, Genetics and Environmental Protection, Tomsk State University, Tomsk, Russia, 634050.
| | - Alexey V Onufriev
- Genomics Bioinformatics and Computational Biology, Virginia Tech, Blacksburg, VA, 24061, USA. .,Department of Physics, Virginia Tech, Blacksburg, VA, 24060, USA. .,Department of Computer Science, Virginia Tech, Blacksburg, VA, 24061, USA. .,Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA, 24061, USA.
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10
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Li Q, Tjong H, Li X, Gong K, Zhou XJ, Chiolo I, Alber F. The three-dimensional genome organization of Drosophila melanogaster through data integration. Genome Biol 2017; 18:145. [PMID: 28760140 PMCID: PMC5576134 DOI: 10.1186/s13059-017-1264-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Accepted: 06/26/2017] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Genome structures are dynamic and non-randomly organized in the nucleus of higher eukaryotes. To maximize the accuracy and coverage of three-dimensional genome structural models, it is important to integrate all available sources of experimental information about a genome's organization. It remains a major challenge to integrate such data from various complementary experimental methods. Here, we present an approach for data integration to determine a population of complete three-dimensional genome structures that are statistically consistent with data from both genome-wide chromosome conformation capture (Hi-C) and lamina-DamID experiments. RESULTS Our structures resolve the genome at the resolution of topological domains, and reproduce simultaneously both sets of experimental data. Importantly, this data deconvolution framework allows for structural heterogeneity between cells, and hence accounts for the expected plasticity of genome structures. As a case study we choose Drosophila melanogaster embryonic cells, for which both data types are available. Our three-dimensional genome structures have strong predictive power for structural features not directly visible in the initial data sets, and reproduce experimental hallmarks of the D. melanogaster genome organization from independent and our own imaging experiments. Also they reveal a number of new insights about genome organization and its functional relevance, including the preferred locations of heterochromatic satellites of different chromosomes, and observations about homologous pairing that cannot be directly observed in the original Hi-C or lamina-DamID data. CONCLUSIONS Our approach allows systematic integration of Hi-C and lamina-DamID data for complete three-dimensional genome structure calculation, while also explicitly considering genome structural variability.
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Affiliation(s)
- Qingjiao Li
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA, 90089, USA
| | - Harianto Tjong
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA, 90089, USA
| | - Xiao Li
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA, 90089, USA
| | - Ke Gong
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA, 90089, USA
| | - Xianghong Jasmine Zhou
- Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California, Los Angeles, USA
| | - Irene Chiolo
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA, 90089, USA.
| | - Frank Alber
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA, 90089, USA.
- Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90089, USA.
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Tissue-specific features of the X chromosome and nucleolus spatial dynamics in a malaria mosquito, Anopheles atroparvus. PLoS One 2017; 12:e0171290. [PMID: 28158219 PMCID: PMC5291520 DOI: 10.1371/journal.pone.0171290] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 01/19/2017] [Indexed: 02/08/2023] Open
Abstract
Spatial organization of chromosome territories is important for maintenance of genomic stability and regulation of gene expression. Recent studies have shown tissue-specific features of chromosome attachments to the nuclear envelope in various organisms including malaria mosquitoes. However, other spatial characteristics of nucleus organization, like volume and shape of chromosome territories, have not been studied in Anopheles. We conducted a thorough analysis of tissue-specific features of the X chromosome and nucleolus volume and shape in follicular epithelium and nurse cells of the Anopheles atroparvus ovaries using a modern open-source software. DNA of the polytene X chromosome from ovarian nurse cells was obtained by microdissection and was used as a template for amplification with degenerate oligo primers. A fluorescently labeled X chromosome painting probe was hybridized with formaldehyde-fixed ovaries of mosquitoes using a 3D-FISH method. The nucleolus was stained by immunostaining with an anti-fibrillarin antibody. The analysis was conducted with TANGO-a software for a chromosome spatial organization analysis. We show that the volume and position of the X chromosome have tissue-specific characteristics. Unlike nurse cell nuclei, the growth of follicular epithelium nuclei is not accompanied with the proportional growth of the X chromosome. However, the shape of the X chromosome does not differ between the tissues. The dynamics of the X chromosome attachment regions location is tissue-specific and it is correlated with the process of nucleus growth in follicular epithelium and nurse cells.
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12
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Kinney NA, Onufriev AV, Sharakhov IV. Quantified effects of chromosome-nuclear envelope attachments on 3D organization of chromosomes. Nucleus 2016; 6:212-24. [PMID: 26068134 DOI: 10.1080/19491034.2015.1056441] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
We use a combined experimental and computational approach to study the effects of chromosome-nuclear envelope (Chr-NE) attachments on the 3D genome organization of Drosophila melanogaster (fruit fly) salivary gland nuclei. We consider 3 distinct models: a Null model - without specific Chr-NE attachments, a 15-attachment model - with 15 previously known Chr-NE attachments, and a 48-attachment model - with 15 original and 33 recently identified Chr-NE attachments. The radial densities of chromosomes in the models are compared to the densities observed in 100 experimental images of optically sectioned salivary gland nuclei forming "z-stacks." Most of the experimental z-stacks support the Chr-NE 48-attachment model suggesting that as many as 48 chromosome loci with appreciable affinity for the NE are necessary to reproduce the experimentally observed distribution of chromosome density in fruit fly nuclei. Next, we investigate if and how the presence and the number of Chr-NE attachments affect several key characteristics of 3D genome organization: chromosome territories and gene-gene contacts. This analysis leads to novel insight about the possible role of Chr-NE attachments in regulating the genome architecture. Specifically, we find that model nuclei with more numerous Chr-NE attachments form more distinct chromosome territories and their chromosomes intertwine less frequently. Intra-chromosome and intra-arm contacts are more common in model nuclei with Chr-NE attachments compared to the Null model (no specific attachments), while inter-chromosome and inter-arm contacts are less common in nuclei with Chr-NE attachments. We demonstrate that Chr-NE attachments increase the specificity of long-range inter-chromosome and inter-arm contacts. The predicted effects of Chr-NE attachments are rationalized by intuitive volume vs. surface accessibility arguments.
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Affiliation(s)
- Nicholas Allen Kinney
- a Genomics Bioinformatics and Computational Biology; Virginia Tech ; Blacksburg , VA , USA
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13
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Sharakhov IV, Sharakhova MV. Heterochromatin, histone modifications, and nuclear architecture in disease vectors. CURRENT OPINION IN INSECT SCIENCE 2015; 10:110-117. [PMID: 26097808 PMCID: PMC4470418 DOI: 10.1016/j.cois.2015.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Interactions between a pathogen and a vector are plastic and dynamic. Such interactions can be more rapidly accommodated by epigenetic changes than by genetic mutations. Gene expression can be affected by the proximity to the heterochromatin, by local histone modifications, and by the three-dimensional position within the nucleus. Recent studies of disease vectors indicate that gene regulation by these factors can be important for susceptibility to pathogens, reproduction, immunity, development, and longevity. Knowledge about heterochromatin, histone modifications, and nuclear architecture will help our understanding of epigenetic mechanisms that control gene function at traits related to vectorial capacity.
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Affiliation(s)
- Igor V Sharakhov
- Department of Entomology, Virginia Tech, Blacksburg, Virginia, USA
| | - Maria V Sharakhova
- Department of Entomology, Virginia Tech, Blacksburg, Virginia, USA ; Research Institute of Biology and Biophysics, Tomsk State University, Tomsk, Russia
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14
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Artemov G, Bondarenko S, Sapunov G, Stegniy V. Tissue-specific differences in the spatial interposition of X-chromosome and 3R chromosome regions in the malaria mosquito Anopheles messeae Fall. PLoS One 2015; 10:e0115281. [PMID: 25671311 PMCID: PMC4324937 DOI: 10.1371/journal.pone.0115281] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2014] [Accepted: 11/22/2014] [Indexed: 11/19/2022] Open
Abstract
Spatial organization of a chromosome in a nucleus is very important in biology but many aspects of it are still generally unresolved. We focused on tissue-specific features of chromosome architecture in closely related malaria mosquitoes, which have essential inter-specific differences in polytene chromosome attachments in nurse cells. We showed that the region responsible for X-chromosome attachment interacts with nuclear lamina stronger in nurse cells, then in salivary glands cells in Anopheles messeae Fall. The inter-tissue differences were demonstrated more convincingly in an experiment of two distinct chromosomes interposition in the nucleus space of cells from four tissues. Microdissected DNA-probes from nurse cells X-chromosome (2BC) and 3R chromosomes (32D) attachment regions were hybridized with intact nuclei of nurse cells, salivary gland cells, follicle epithelium cells and imaginal disсs cells in 3D-FISH experiments. We showed that only salivary gland cells and follicle epithelium cells have no statistical differences in the interposition of 2BC and 32D. Generally, the X-chromosome and 3R chromosome are located closer to each other in cells of the somatic system in comparison with nurse cells on average. The imaginal disсs cell nuclei have an intermediate arrangement of chromosome interposition, similar to other somatic cells and nurse cells. In spite of species-specific chromosome attachments there are no differences in interposition of nurse cells chromosomes in An. messeae and An. atroparvus Thiel. Nurse cells have an unusual chromosome arrangement without a chromocenter, which could be due to the special mission of generative system cells in ontogenesis and evolution.
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Affiliation(s)
| | - Semen Bondarenko
- Institute of Theoretical and Experimental Biophysics of RAS, Pushchino, Moscow region, Russia
| | - Gleb Sapunov
- Institute for Biological Instrumentation of RAS, Pushchino, Moscow region, Russia
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Bozler J, Nguyen HQ, Rogers GC, Bosco G. Condensins exert force on chromatin-nuclear envelope tethers to mediate nucleoplasmic reticulum formation in Drosophila melanogaster. G3 (BETHESDA, MD.) 2014; 5:341-52. [PMID: 25552604 PMCID: PMC4349088 DOI: 10.1534/g3.114.015685] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 12/22/2014] [Indexed: 01/03/2023]
Abstract
Although the nuclear envelope is known primarily for its role as a boundary between the nucleus and cytoplasm in eukaryotes, it plays a vital and dynamic role in many cellular processes. Studies of nuclear structure have revealed tissue-specific changes in nuclear envelope architecture, suggesting that its three-dimensional structure contributes to its functionality. Despite the importance of the nuclear envelope, the factors that regulate and maintain nuclear envelope shape remain largely unexplored. The nuclear envelope makes extensive and dynamic interactions with the underlying chromatin. Given this inexorable link between chromatin and the nuclear envelope, it is possible that local and global chromatin organization reciprocally impact nuclear envelope form and function. In this study, we use Drosophila salivary glands to show that the three-dimensional structure of the nuclear envelope can be altered with condensin II-mediated chromatin condensation. Both naturally occurring and engineered chromatin-envelope interactions are sufficient to allow chromatin compaction forces to drive distortions of the nuclear envelope. Weakening of the nuclear lamina further enhanced envelope remodeling, suggesting that envelope structure is capable of counterbalancing chromatin compaction forces. Our experiments reveal that the nucleoplasmic reticulum is born of the nuclear envelope and remains dynamic in that they can be reabsorbed into the nuclear envelope. We propose a model where inner nuclear envelope-chromatin tethers allow interphase chromosome movements to change nuclear envelope morphology. Therefore, interphase chromatin compaction may be a normal mechanism that reorganizes nuclear architecture, while under pathological conditions, such as laminopathies, compaction forces may contribute to defects in nuclear morphology.
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Affiliation(s)
- Julianna Bozler
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Huy Q Nguyen
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
| | - Gregory C Rogers
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, Arizona 85724
| | - Giovanni Bosco
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire 03755
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