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Bing X, Ke W, Fujioka M, Kurbidaeva A, Levitt S, Levine M, Schedl P, Jaynes JB. Chromosome structure in Drosophila is determined by boundary pairing not loop extrusion. eLife 2024; 13:RP94070. [PMID: 39110499 PMCID: PMC11305675 DOI: 10.7554/elife.94070] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024] Open
Abstract
Two different models have been proposed to explain how the endpoints of chromatin looped domains ('TADs') in eukaryotic chromosomes are determined. In the first, a cohesin complex extrudes a loop until it encounters a boundary element roadblock, generating a stem-loop. In this model, boundaries are functionally autonomous: they have an intrinsic ability to halt the movement of incoming cohesin complexes that is independent of the properties of neighboring boundaries. In the second, loops are generated by boundary:boundary pairing. In this model, boundaries are functionally non-autonomous, and their ability to form a loop depends upon how well they match with their neighbors. Moreover, unlike the loop-extrusion model, pairing interactions can generate both stem-loops and circle-loops. We have used a combination of MicroC to analyze how TADs are organized, and experimental manipulations of the even skipped TAD boundary, homie, to test the predictions of the 'loop-extrusion' and the 'boundary-pairing' models. Our findings are incompatible with the loop-extrusion model, and instead suggest that the endpoints of TADs in flies are determined by a mechanism in which boundary elements physically pair with their partners, either head-to-head or head-to-tail, with varying degrees of specificity. Although our experiments do not address how partners find each other, the mechanism is unlikely to require loop extrusion.
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Affiliation(s)
- Xinyang Bing
- Lewis Sigler Institute, Princeton UniversityPrincetonUnited States
| | - Wenfan Ke
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Miki Fujioka
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphiaUnited States
| | - Amina Kurbidaeva
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Sarah Levitt
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Mike Levine
- Lewis Sigler Institute, Princeton UniversityPrincetonUnited States
| | - Paul Schedl
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - James B Jaynes
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphiaUnited States
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2
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Ke W, Fujioka M, Schedl P, Jaynes JB. Stem-loop and circle-loop TADs generated by directional pairing of boundary elements have distinct physical and regulatory properties. eLife 2024; 13:RP94114. [PMID: 39110491 PMCID: PMC11305674 DOI: 10.7554/elife.94114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024] Open
Abstract
The chromosomes in multicellular eukaryotes are organized into a series of topologically independent loops called TADs. In flies, TADs are formed by physical interactions between neighboring boundaries. Fly boundaries exhibit distinct partner preferences, and pairing interactions between boundaries are typically orientation-dependent. Pairing can be head-to-tail or head-to-head. The former generates a stem-loop TAD, while the latter gives a circle-loop TAD. The TAD that encompasses the Drosophila even skipped (eve) gene is formed by the head-to-tail pairing of the nhomie and homie boundaries. To explore the relationship between loop topology and the physical and regulatory landscape, we flanked the nhomie boundary region with two attP sites. The attP sites were then used to generate four boundary replacements: λ DNA, nhomie forward (WT orientation), nhomie reverse (opposite of WT orientation), and homie forward (same orientation as WT homie). The nhomie forward replacement restores the WT physical and regulatory landscape: in MicroC experiments, the eve TAD is a 'volcano' triangle topped by a plume, and the eve gene and its regulatory elements are sequestered from interactions with neighbors. The λ DNA replacement lacks boundary function: the endpoint of the 'new' eve TAD on the nhomie side is ill-defined, and eve stripe enhancers activate a nearby gene, eIF3j. While nhomie reverse and homie forward restore the eve TAD, the topology is a circle-loop, and this changes the local physical and regulatory landscape. In MicroC experiments, the eve TAD interacts with its neighbors, and the plume at the top of the eve triangle peak is converted to a pair of 'clouds' of contacts with the next-door TADs. Consistent with the loss of isolation afforded by the stem-loop topology, the eve enhancers weakly activate genes in the neighboring TADs. Conversely, eve function is partially disrupted.
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Affiliation(s)
- Wenfan Ke
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - Miki Fujioka
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphiaUnited States
| | - Paul Schedl
- Department of Molecular Biology, Princeton UniversityPrincetonUnited States
| | - James B Jaynes
- Department of Biochemistry and Molecular Biology, Thomas Jefferson UniversityPhiladelphiaUnited States
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3
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Melnikova L, Molodina V, Georgiev P, Golovnin A. Development of a New Model System to Study Long-Distance Interactions Supported by Architectural Proteins. Int J Mol Sci 2024; 25:4617. [PMID: 38731837 PMCID: PMC11083095 DOI: 10.3390/ijms25094617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 04/20/2024] [Accepted: 04/21/2024] [Indexed: 05/13/2024] Open
Abstract
Chromatin architecture is critical for the temporal and tissue-specific activation of genes that determine eukaryotic development. The functional interaction between enhancers and promoters is controlled by insulators and tethering elements that support specific long-distance interactions. However, the mechanisms of the formation and maintenance of long-range interactions between genome regulatory elements remain poorly understood, primarily due to the lack of convenient model systems. Drosophila became the first model organism in which architectural proteins that determine the activity of insulators were described. In Drosophila, one of the best-studied DNA-binding architectural proteins, Su(Hw), forms a complex with Mod(mdg4)-67.2 and CP190 proteins. Using a combination of CRISPR/Cas9 genome editing and attP-dependent integration technologies, we created a model system in which the promoters and enhancers of two reporter genes are separated by 28 kb. In this case, enhancers effectively stimulate reporter gene promoters in cis and trans only in the presence of artificial Su(Hw) binding sites (SBS), in both constructs. The expression of the mutant Su(Hw) protein, which cannot interact with CP190, and the mutation inactivating Mod(mdg4)-67.2, lead to the complete loss or significant weakening of enhancer-promoter interactions, respectively. The results indicate that the new model system effectively identifies the role of individual subunits of architectural protein complexes in forming and maintaining specific long-distance interactions in the D. melanogaster model.
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Affiliation(s)
- Larisa Melnikova
- Department of Drosophila Molecular Genetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, Moscow 119334, Russia;
| | - Varvara Molodina
- Department of Drosophila Molecular Genetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, Moscow 119334, Russia;
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, Moscow 119334, Russia;
| | - Anton Golovnin
- Department of Drosophila Molecular Genetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov Street, Moscow 119334, Russia;
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4
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Shah HA, Baker T, Schell CO, Kuwawenaruwa A, Awadh K, Khalid K, Kairu A, Were V, Barasa E, Baker P, Guinness L. Cost Effectiveness of Strategies for Caring for Critically Ill Patients with COVID-19 in Tanzania. PHARMACOECONOMICS - OPEN 2023:10.1007/s41669-023-00418-x. [PMID: 37178434 PMCID: PMC10181924 DOI: 10.1007/s41669-023-00418-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 04/27/2023] [Indexed: 05/15/2023]
Abstract
BACKGROUND The resources for critical care are limited in many settings, exacerbating the significant morbidity and mortality associated with critical illness. Budget constraints can lead to choices between investing in advanced critical care (e.g. mechanical ventilators in intensive care units) or more basic critical care such as Essential Emergency and Critical Care (EECC; e.g. vital signs monitoring, oxygen therapy, and intravenous fluids). METHODS We investigated the cost effectiveness of providing EECC and advanced critical care in Tanzania in comparison with providing 'no critical care' or 'district hospital-level critical care' using coronavirus disease 2019 (COVID-19) as a tracer condition. We developed an open-source Markov model ( https://github.com/EECCnetwork/POETIC_CEA ) to estimate costs and disability-adjusted life-years (DALYs) averted, using a provider perspective, a 28-day time horizon, patient outcomes obtained from an elicitation method involving a seven-member expert group, a normative costing study, and published literature. We performed a univariate and probabilistic sensitivity analysis to assess the robustness of our results. , RESULTS EECC is cost effective 94% and 99% of the time when compared with no critical care (incremental cost-effectiveness ratio [ICER] $37 [-$9 to $790] per DALY averted) and district hospital-level critical care (ICER $14 [-$200 to $263] per DALY averted), respectively, relative to the lowest identified estimate of the willingness-to-pay threshold for Tanzania ($101 per DALY averted). Advanced critical care is cost effective 27% and 40% of the time, when compared with the no critical care or district hospital-level critical care scenarios, respectively. CONCLUSION For settings where there is limited or no critical care delivery, implementation of EECC could be a highly cost-effective investment. It could reduce mortality and morbidity for critically ill COVID-19 patients, and its cost effectiveness falls within the range considered 'highly cost effective'. Further research is needed to explore the potential of EECC to generate even greater benefits and value for money when patients with diagnoses other than COVID-19 are accounted for.
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Affiliation(s)
| | - Tim Baker
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, UK
- Ifakara Health Institute, Dar es Salaam, Tanzania
- Muhimbili University of Health and Allied Sciences, Dar es Salaam, United Republic of Tanzania
- Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden
| | - Carl Otto Schell
- Department of Global Public Health, Karolinska Institutet, Stockholm, Sweden
- Centre for Clinical Research Sörmland, Uppsala University, Eskilstuna, Sweden
- Department of Medicine, Nyköping Hospital, Nyköping, Sweden
| | | | - Khamis Awadh
- Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Karima Khalid
- Ifakara Health Institute, Dar es Salaam, Tanzania
- Muhimbili University of Health and Allied Sciences, Dar es Salaam, United Republic of Tanzania
| | - Angela Kairu
- Health Economics Research Unit, KEMRI Wellcome Trust Research Programme, Nairobi, Kenya
| | - Vincent Were
- Health Economics Research Unit, KEMRI Wellcome Trust Research Programme, Nairobi, Kenya
| | - Edwine Barasa
- Health Economics Research Unit, KEMRI Wellcome Trust Research Programme, Nairobi, Kenya
- Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | - Lorna Guinness
- Center for Global Development, London, UK.
- Global Health Economics Centre, London School of Hygiene and Tropical Medicine, London, UK.
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5
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Mechanisms of Interaction between Enhancers and Promoters in Three Drosophila Model Systems. Int J Mol Sci 2023; 24:ijms24032855. [PMID: 36769179 PMCID: PMC9917889 DOI: 10.3390/ijms24032855] [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: 12/29/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
In higher eukaryotes, the regulation of developmental gene expression is determined by enhancers, which are often located at a large distance from the promoters they regulate. Therefore, the architecture of chromosomes and the mechanisms that determine the functional interaction between enhancers and promoters are of decisive importance in the development of organisms. Mammals and the model animal Drosophila have homologous key architectural proteins and similar mechanisms in the organization of chromosome architecture. This review describes the current progress in understanding the mechanisms of the formation and regulation of long-range interactions between enhancers and promoters at three well-studied key regulatory loci in Drosophila.
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6
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Urban EA, Chernoff C, Layng KV, Han J, Anderson C, Konzman D, Johnston RJ. Activating and repressing gene expression between chromosomes during stochastic fate specification. Cell Rep 2023; 42:111910. [PMID: 36640351 PMCID: PMC9976292 DOI: 10.1016/j.celrep.2022.111910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 10/28/2022] [Accepted: 12/09/2022] [Indexed: 12/31/2022] Open
Abstract
DNA elements act across long genomic distances to regulate gene expression. During transvection in Drosophila, DNA elements on one allele of a gene act between chromosomes to regulate expression of the other allele. Little is known about the biological roles and developmental regulation of transvection. Here, we study the stochastic expression of spineless (ss) in photoreceptors in the fly eye to understand transvection. We determine a biological role for transvection in regulating expression of naturally occurring ss alleles. We identify DNA elements required for activating and repressing transvection. Different enhancers participate in transvection at different times during development to promote gene expression and specify cell fates. Bringing a silencer element on a heterologous chromosome into proximity with the ss locus "reconstitutes" the gene, leading to repression. Our studies show that transvection regulates gene expression via distinct DNA elements at specific timepoints in development, with implications for genome organization and architecture.
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Affiliation(s)
- Elizabeth A. Urban
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,These authors contributed equally
| | - Chaim Chernoff
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,Present address: Harvard Stem Cell Institute, Harvard University, 7 Divinity Avenue, Cambridge, MA 02138, USA,These authors contributed equally
| | - Kayla Viets Layng
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Jeong Han
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Caitlin Anderson
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Daniel Konzman
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA
| | - Robert J. Johnston
- Department of Biology, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA,Lead contact,Correspondence:
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7
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Fleck K, Raj R, Erceg J. The 3D genome landscape: Diverse chromosomal interactions and their functional implications. Front Cell Dev Biol 2022; 10:968145. [PMID: 36036013 PMCID: PMC9402908 DOI: 10.3389/fcell.2022.968145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/19/2022] [Indexed: 11/13/2022] Open
Abstract
Genome organization includes contacts both within a single chromosome and between distinct chromosomes. Thus, regulatory organization in the nucleus may include interplay of these two types of chromosomal interactions with genome activity. Emerging advances in omics and single-cell imaging technologies have allowed new insights into chromosomal contacts, including those of homologs and sister chromatids, and their significance to genome function. In this review, we highlight recent studies in this field and discuss their impact on understanding the principles of chromosome organization and associated functional implications in diverse cellular processes. Specifically, we describe the contributions of intra-chromosomal, inter-homolog, and inter-sister chromatid contacts to genome organization and gene expression.
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Affiliation(s)
- Katherine Fleck
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Romir Raj
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
| | - Jelena Erceg
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, United States
- Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, United States
- *Correspondence: Jelena Erceg,
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8
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Galouzis CC, Prud’homme B. Relevance and mechanisms of transvection. C R Biol 2021; 344:373-387. [DOI: 10.5802/crbiol.69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 11/15/2021] [Indexed: 11/24/2022]
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9
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Erokhin M, Gorbenko F, Lomaev D, Mazina MY, Mikhailova A, Garaev AK, Parshikov A, Vorobyeva NE, Georgiev P, Schedl P, Chetverina D. Boundaries potentiate polycomb response element-mediated silencing. BMC Biol 2021; 19:113. [PMID: 34078365 PMCID: PMC8170967 DOI: 10.1186/s12915-021-01047-8] [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] [Received: 02/11/2021] [Accepted: 05/07/2021] [Indexed: 12/21/2022] Open
Abstract
Background Epigenetic memory plays a critical role in the establishment and maintenance of cell identities in multicellular organisms. Polycomb and trithorax group (PcG and TrxG) proteins are responsible for epigenetic memory, and in flies, they are recruited to specialized DNA regulatory elements termed polycomb response elements (PREs). Previous transgene studies have shown that PREs can silence reporter genes outside of their normal context, often by pairing sensitive (PSS) mechanism; however, their silencing activity is non-autonomous and depends upon the surrounding chromatin context. It is not known why PRE activity depends on the local environment or what outside factors can induce silencing. Results Using an attP system in Drosophila, we find that the so-called neutral chromatin environments vary substantially in their ability to support the silencing activity of the well-characterized bxdPRE. In refractory chromosomal contexts, factors required for PcG-silencing are unable to gain access to the PRE. Silencing activity can be rescued by linking the bxdPRE to a boundary element (insulator). When placed next to the PRE, the boundaries induce an alteration in chromatin structure enabling factors critical for PcG silencing to gain access to the bxdPRE. When placed at a distance from the bxdPRE, boundaries induce PSS by bringing the bxdPREs on each homolog in close proximity. Conclusion This proof-of-concept study demonstrates that the repressing activity of PREs can be induced or enhanced by nearby boundary elements. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s12915-021-01047-8.
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Affiliation(s)
- Maksim Erokhin
- Group of Chromatin Biology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia.
| | - Fedor Gorbenko
- Group of Chromatin Biology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia.,Present address: Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Dmitry Lomaev
- Group of Epigenetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia
| | - Marina Yu Mazina
- Group of Transcriptional Complexes Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anna Mikhailova
- Group of Chromatin Biology, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia
| | - Azat K Garaev
- Laboratory of Structural and Functional Organization of Chromosomes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia
| | - Aleksander Parshikov
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia
| | - Nadezhda E Vorobyeva
- Group of Transcriptional Complexes Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia
| | - Paul Schedl
- Department of Molecular Biology Princeton University, Princeton, NJ, 08544, USA.
| | - Darya Chetverina
- Group of Epigenetics, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow, 119334, Russia.
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10
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Nichols MH, Corces VG. Principles of 3D compartmentalization of the human genome. Cell Rep 2021; 35:109330. [PMID: 34192544 PMCID: PMC8265014 DOI: 10.1016/j.celrep.2021.109330] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2020] [Revised: 04/01/2021] [Accepted: 06/09/2021] [Indexed: 11/21/2022] Open
Abstract
Chromatin is organized in the nucleus via CTCF loops and compartmental domains. Here, we compare different cell types to identify distinct paradigms of compartmental domain formation in human tissues. We identify and quantify compartmental forces correlated with histone modifications characteristic of transcriptional activity and previously underappreciated roles for distinct compartmental domains correlated with the presence of H3K27me3 and H3K9me3, respectively. We present a computer simulation model capable of predicting compartmental organization based on the biochemical characteristics of independent chromatin features. Using this model, we show that the underlying forces responsible for compartmental domain formation in human cells are conserved and that the diverse compartmentalization patterns seen across cell types are due to differences in chromatin features. We extend these findings to Drosophila to suggest that the same principles are at work beyond humans. These results offer mechanistic insights into the fundamental forces driving the 3D organization of the genome. Using high-resolution Hi-C data and computer simulations, Nichols and Corces show that compartments arise as a consequence of interactions among proteins that correlate with the presence of H3K27ac, H3K27me3, and H3K9me3, suggesting that human cells contain at least three distinct compartments. The same principles apply to other organisms.
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Affiliation(s)
- Michael H Nichols
- Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Atlanta, GA 30322, USA
| | - Victor G Corces
- Department of Human Genetics, Emory University School of Medicine, 615 Michael St., Atlanta, GA 30322, USA.
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11
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Kyrchanova O, Georgiev P. Mechanisms of Enhancer-Promoter Interactions in Higher Eukaryotes. Int J Mol Sci 2021; 22:ijms22020671. [PMID: 33445415 PMCID: PMC7828040 DOI: 10.3390/ijms22020671] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 12/28/2020] [Accepted: 01/09/2021] [Indexed: 12/13/2022] Open
Abstract
In higher eukaryotes, enhancers determine the activation of developmental gene transcription in specific cell types and stages of embryogenesis. Enhancers transform the signals produced by various transcription factors within a given cell, activating the transcription of the targeted genes. Often, developmental genes can be associated with dozens of enhancers, some of which are located at large distances from the promoters that they regulate. Currently, the mechanisms underlying specific distance interactions between enhancers and promoters remain poorly understood. This review briefly describes the properties of enhancers and discusses the mechanisms of distance interactions and potential proteins involved in this process.
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12
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Interplay of pericentromeric genome organization and chromatin landscape regulates the expression of Drosophila melanogaster heterochromatic genes. Epigenetics Chromatin 2020; 13:41. [PMID: 33028366 PMCID: PMC7541242 DOI: 10.1186/s13072-020-00358-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 09/15/2020] [Indexed: 01/04/2023] Open
Abstract
Background Transcription of genes residing within constitutive heterochromatin is paradoxical to the tenets of epigenetic code. The regulatory mechanisms of Drosophila melanogaster heterochromatic gene transcription remain largely unknown. Emerging evidence suggests that genome organization and transcriptional regulation are inter-linked. However, the pericentromeric genome organization is relatively less studied. Therefore, we sought to characterize the pericentromeric genome organization and understand how this organization along with the pericentromeric factors influences heterochromatic gene expression. Results Here, we characterized the pericentromeric genome organization in Drosophila melanogaster using 5C sequencing. Heterochromatic topologically associating domains (Het TADs) correlate with distinct epigenomic domains of active and repressed heterochromatic genes at the pericentromeres. These genes are known to depend on the heterochromatic landscape for their expression. However, HP1a or Su(var)3-9 RNAi has minimal effects on heterochromatic gene expression, despite causing significant changes in the global Het TAD organization. Probing further into this observation, we report the role of two other chromatin proteins enriched at the pericentromeres-dMES-4 and dADD1 in regulating the expression of a subset of heterochromatic genes. Conclusions Distinct pericentromeric genome organization and chromatin landscapes maintained by the interplay of heterochromatic factors (HP1a, H3K9me3, dMES-4 and dADD1) are sufficient to support heterochromatic gene expression despite the loss of global Het TAD structure. These findings open new avenues for future investigations into the mechanisms of heterochromatic gene expression.
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13
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Santos AP, Gaudin V, Mozgová I, Pontvianne F, Schubert D, Tek AL, Dvořáčková M, Liu C, Fransz P, Rosa S, Farrona S. Tidying-up the plant nuclear space: domains, functions, and dynamics. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:5160-5178. [PMID: 32556244 PMCID: PMC8604271 DOI: 10.1093/jxb/eraa282] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 06/12/2020] [Indexed: 05/07/2023]
Abstract
Understanding how the packaging of chromatin in the nucleus is regulated and organized to guide complex cellular and developmental programmes, as well as responses to environmental cues is a major question in biology. Technological advances have allowed remarkable progress within this field over the last years. However, we still know very little about how the 3D genome organization within the cell nucleus contributes to the regulation of gene expression. The nuclear space is compartmentalized in several domains such as the nucleolus, chromocentres, telomeres, protein bodies, and the nuclear periphery without the presence of a membrane around these domains. The role of these domains and their possible impact on nuclear activities is currently under intense investigation. In this review, we discuss new data from research in plants that clarify functional links between the organization of different nuclear domains and plant genome function with an emphasis on the potential of this organization for gene regulation.
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Affiliation(s)
- Ana Paula Santos
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova
de Lisboa, Oeiras, Portugal
| | - Valérie Gaudin
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université
Paris-Saclay, Versailles, France
| | - Iva Mozgová
- Biology Centre of the Czech Academy of Sciences, České
Budějovice, Czech Republic
- Faculty of Science, University of South Bohemia, České
Budějovice, Czech Republic
| | - Frédéric Pontvianne
- CNRS, Laboratoire Génome et Développement des Plantes (LGDP), Université de
Perpignan Via Domitia, Perpignan, France
| | - Daniel Schubert
- Institute for Biology, Freie Universität Berlin, Berlin, Germany
| | - Ahmet L Tek
- Agricultural Genetic Engineering Department, Niğde Ömer Halisdemir
University, Niğde, Turkey
| | | | - Chang Liu
- Center for Plant Molecular Biology (ZMBP), University of
Tübingen, Tübingen, Germany
- Institute of Biology, University of Hohenheim, Stuttgart,
Germany
| | - Paul Fransz
- University of Amsterdam, Amsterdam, The
Netherlands
| | - Stefanie Rosa
- Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Sara Farrona
- Plant and AgriBiosciences Centre, Ryan Institute, NUI Galway,
Galway, Ireland
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14
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Fresán U, Rodríguez-Sánchez MA, Reina O, Corces VG, Espinàs ML. Haspin kinase modulates nuclear architecture and Polycomb-dependent gene silencing. PLoS Genet 2020; 16:e1008962. [PMID: 32750047 PMCID: PMC7428214 DOI: 10.1371/journal.pgen.1008962] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 08/14/2020] [Accepted: 06/29/2020] [Indexed: 12/14/2022] Open
Abstract
Haspin, a highly conserved kinase in eukaryotes, has been shown to be responsible for phosphorylation of histone H3 at threonine 3 (H3T3ph) during mitosis, in mammals and yeast. Here we report that haspin is the kinase that phosphorylates H3T3 in Drosophila melanogaster and it is involved in sister chromatid cohesion during mitosis. Our data reveal that haspin also phosphorylates H3T3 in interphase. H3T3ph localizes in broad silenced domains at heterochromatin and lamin-enriched euchromatic regions. Loss of haspin compromises insulator activity in enhancer-blocking assays and triggers a decrease in nuclear size that is accompanied by changes in nuclear envelope morphology. We show that haspin is a suppressor of position-effect variegation involved in heterochromatin organization. Our results also demonstrate that haspin is necessary for pairing-sensitive silencing and it is required for robust Polycomb-dependent homeotic gene silencing. Haspin associates with the cohesin complex in interphase, mediates Pds5 binding to chromatin and cooperates with Pds5-cohesin to modify Polycomb-dependent homeotic transformations. Therefore, this study uncovers an unanticipated role for haspin kinase in genome organization of interphase cells and demonstrates that haspin is required for homeotic gene regulation.
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Affiliation(s)
- Ujué Fresán
- Institut de Biologia Molecular de Barcelona, IBMB-CSIC, Barcelona, Spain
- Institute for Research in Biomedicine IRB, Barcelona, Spain
| | | | - Oscar Reina
- Bioinformatics and Biostatistics Unit, Institute for Research in Biomedicine IRB, Barcelona, Spain
| | - Victor G. Corces
- Department of Human Genetics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - M. Lluisa Espinàs
- Institut de Biologia Molecular de Barcelona, IBMB-CSIC, Barcelona, Spain
- Institute for Research in Biomedicine IRB, Barcelona, Spain
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15
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Boettiger A, Murphy S. Advances in Chromatin Imaging at Kilobase-Scale Resolution. Trends Genet 2020; 36:273-287. [PMID: 32007290 PMCID: PMC7197267 DOI: 10.1016/j.tig.2019.12.010] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/12/2019] [Accepted: 12/20/2019] [Indexed: 12/17/2022]
Abstract
It is now widely appreciated that the spatial organization of the genome is nonrandom, and its complex 3D folding has important consequences for many genome processes. Recent developments in multiplexed, super-resolution microscopy have enabled an unprecedented view of the polymeric structure of chromatin - from the loose folds of whole chromosomes to the detailed loops of cis-regulatory elements that regulate gene expression. Facilitated by the use of robotics, microfluidics, and improved approaches to super-resolution, thousands to hundreds of thousands of individual cells can now be analyzed in an individual experiment. This has led to new insights into the nature of genomic structural features identified by sequencing, such as topologically associated domains (TADs), and the nature of enhancer-promoter interactions underlying transcriptional regulation. We review these recent improvements.
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Affiliation(s)
- Alistair Boettiger
- Department of Developmental Biology, Stanford University, Stanford, CA 94305, USA.
| | - Sedona Murphy
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
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16
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Kyrchanova O, Maksimenko O, Ibragimov A, Sokolov V, Postika N, Lukyanova M, Schedl P, Georgiev P. The insulator functions of the Drosophila polydactyl C2H2 zinc finger protein CTCF: Necessity versus sufficiency. SCIENCE ADVANCES 2020; 6:eaaz3152. [PMID: 32232161 PMCID: PMC7096168 DOI: 10.1126/sciadv.aaz3152] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 01/03/2020] [Indexed: 06/10/2023]
Abstract
In mammals, a C2H2 zinc finger (C2H2) protein, CTCF, acts as the master regulator of chromosomal architecture and of the expression of Hox gene clusters. Like mammalian CTCF, the Drosophila homolog, dCTCF, localizes to boundaries in the bithorax complex (BX-C). Here, we have determined the minimal requirements for the assembly of a functional boundary by dCTCF and two other C2H2 zinc finger proteins, Pita and Su(Hw). Although binding sites for these proteins are essential for the insulator activity of BX-C boundaries, these binding sites alone are insufficient to create a functional boundary. dCTCF cannot effectively bind to a single recognition sequence in chromatin or generate a functional insulator without the help of additional proteins. In addition, for boundary elements in BX-C at least four binding sites for dCTCF or the presence of additional DNA binding factors is required to generate a functional insulator.
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Affiliation(s)
- Olga Kyrchanova
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Oksana Maksimenko
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Airat Ibragimov
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Vladimir Sokolov
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Nikolay Postika
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Maria Lukyanova
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, 34/5 Vavilov St., Moscow 119334, Russia
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17
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Viets K, Sauria MEG, Chernoff C, Rodriguez Viales R, Echterling M, Anderson C, Tran S, Dove A, Goyal R, Voortman L, Gordus A, Furlong EEM, Taylor J, Johnston RJ. Characterization of Button Loci that Promote Homologous Chromosome Pairing and Cell-Type-Specific Interchromosomal Gene Regulation. Dev Cell 2019; 51:341-356.e7. [PMID: 31607649 DOI: 10.1016/j.devcel.2019.09.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 06/07/2019] [Accepted: 09/09/2019] [Indexed: 01/05/2023]
Abstract
Homologous chromosomes colocalize to regulate gene expression in processes including genomic imprinting, X-inactivation, and transvection. In Drosophila, homologous chromosomes pair throughout development, promoting transvection. The "button" model of pairing proposes that specific regions along chromosomes pair with high affinity. Here, we identify buttons interspersed across the fly genome that pair with their homologous sequences, even when relocated to multiple positions in the genome. A majority of transgenes that span a full topologically associating domain (TAD) function as buttons, but not all buttons contain TADs. Additionally, buttons are enriched for insulator protein clusters. Fragments of buttons do not pair, suggesting that combinations of elements within a button are required for pairing. Pairing is necessary but not sufficient for transvection. Additionally, pairing and transvection are stronger in some cell types than in others, suggesting that pairing strength regulates transvection efficiency between cell types. Thus, buttons pair homologous chromosomes to facilitate cell-type-specific interchromosomal gene regulation.
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Affiliation(s)
- Kayla Viets
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Michael E G Sauria
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Chaim Chernoff
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | | | - Max Echterling
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Caitlin Anderson
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Sang Tran
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Abigail Dove
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Raghav Goyal
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Lukas Voortman
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Andrew Gordus
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Eileen E M Furlong
- European Molecular Biology Laboratory, Department of Genome Biology, Heidelberg 69117, Germany
| | - James Taylor
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Robert J Johnston
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA.
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18
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Voigt S, Erpf AC, Stephan W. Decreased Temperature Sensitivity of Vestigial Gene Expression in Temperate Populations of Drosophila melanogaster. Genes (Basel) 2019; 10:genes10070498. [PMID: 31261809 PMCID: PMC6679080 DOI: 10.3390/genes10070498] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 06/05/2019] [Accepted: 06/21/2019] [Indexed: 11/24/2022] Open
Abstract
Drosophila melanogaster recently spread from its tropical origin in Africa and became a cosmopolitan species that has adapted to a wide range of different thermal environments, including temperate climates. An important limiting factor of temperate climates has probably been their low and varying temperatures. The transcriptional output of genes can vary across temperatures, which might have been detrimental while settling in temperate environments. The reduction of temperature-sensitive expression of functionally important genes to ensure consistent levels of gene expression might have been relevant while adapting to such environments. In this study, we focus on the gene vestigial (vg) whose product is a key factor in wing development. We provide evidence that temperature-sensitivity of vg has been buffered in populations from temperate climates. We investigated temperature-sensitivity of vg gene expression in six natural populations, including four temperate populations (three from Europe and one from high-altitude Africa), and two tropical populations from the ancestral species range. All temperate populations exhibited a lower degree of temperature-induced expression plasticity than the tropical populations.
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Affiliation(s)
- Susanne Voigt
- Section of Evolutionary Biology, Department of Biology II, University of Munich, 82152 Planegg-Martinsried, Germany.
- Applied Zoology, Faculty of Biology, Technische Universität Dresden, 01217 Dresden, Germany.
| | - Anna Christina Erpf
- Section of Evolutionary Biology, Department of Biology II, University of Munich, 82152 Planegg-Martinsried, Germany.
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto ON M5G 1X5, Canada.
| | - Wolfgang Stephan
- Section of Evolutionary Biology, Department of Biology II, University of Munich, 82152 Planegg-Martinsried, Germany.
- Leibniz Institute for Evolution and Biodiversity Science, 10115 Berlin, Germany.
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19
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Piwko P, Vitsaki I, Livadaras I, Delidakis C. The Role of Insulators in Transgene Transvection in Drosophila. Genetics 2019; 212:489-508. [PMID: 30948430 PMCID: PMC6553826 DOI: 10.1534/genetics.119.302165] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/02/2019] [Indexed: 12/19/2022] Open
Abstract
Transvection is the phenomenon where a transcriptional enhancer activates a promoter located on the homologous chromosome. It has been amply documented in Drosophila where homologs are closely paired in most, if not all, somatic nuclei, but it has been known to rarely occur in mammals as well. We have taken advantage of site-directed transgenesis to insert reporter constructs into the same genetic locus in Drosophila and have evaluated their ability to engage in transvection by testing many heterozygous combinations. We find that transvection requires the presence of an insulator element on both homologs. Homotypic trans-interactions between four different insulators can support transvection: the gypsy insulator (GI), Wari, Fab-8 and 1A2; GI and Fab-8 are more effective than Wari or 1A2 We show that, in the presence of insulators, transvection displays the characteristics that have been previously described: it requires homolog pairing, but can happen at any of several loci in the genome; a solitary enhancer confronted with an enhancerless reporter is sufficient to drive transcription; it is weaker than the action of the same enhancer-promoter pair in cis, and it is further suppressed by cis-promoter competition. Though necessary, the presence of homotypic insulators is not sufficient for transvection; their position, number and orientation matters. A single GI adjacent to both enhancer and promoter is the optimal configuration. The identity of enhancers and promoters in the vicinity of a trans-interacting insulator pair is also important, indicative of complex insulator-enhancer-promoter interactions.
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Affiliation(s)
- Pawel Piwko
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Biology, University of Crete, Heraklion 70013, Crete, Greece
| | - Ilektra Vitsaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Biology, University of Crete, Heraklion 70013, Crete, Greece
| | - Ioannis Livadaras
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
| | - Christos Delidakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology Hellas, Heraklion 70013, Crete, Greece
- Department of Biology, University of Crete, Heraklion 70013, Crete, Greece
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20
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Highly interacting regions of the human genome are enriched with enhancers and bound by DNA repair proteins. Sci Rep 2019; 9:4577. [PMID: 30872630 PMCID: PMC6418152 DOI: 10.1038/s41598-019-40770-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 02/12/2019] [Indexed: 11/08/2022] Open
Abstract
In specific cases, chromatin clearly forms long-range loops that place distant regulatory elements in close proximity to transcription start sites, but we have limited understanding of many loops identified by Chromosome Conformation Capture (such as Hi-C) analyses. In efforts to elucidate their characteristics and functions, we have identified highly interacting regions (HIRs) using intra-chromosomal Hi-C datasets with a new computational method based on looking at the eigenvector that corresponds to the smallest eigenvalue (here unity). Analysis of these regions using ENCODE data shows that they are in general enriched in bound factors involved in DNA damage repair and have actively transcribed genes. However, both highly transcribed regions as well as transcriptionally inactive regions can form HIRs. The results also indicate that enhancers and super-enhancers in particular form long-range interactions within the same chromosome. The accumulation of DNA repair factors in most identified HIRs suggests that protection from DNA damage in these regions is essential for avoidance of detrimental rearrangements.
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21
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Fedotova A, Clendinen C, Bonchuk A, Mogila V, Aoki T, Georgiev P, Schedl P. Functional dissection of the developmentally restricted BEN domain chromatin boundary factor Insensitive. Epigenetics Chromatin 2019; 12:2. [PMID: 30602385 PMCID: PMC6317261 DOI: 10.1186/s13072-018-0249-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 12/19/2018] [Indexed: 02/06/2023] Open
Abstract
Background Boundaries in the Drosophila bithorax complex delimit autonomous regulatory domains that activate the parasegment (PS)-specific expression of homeotic genes. The Fab-7 boundary separates the iab-6 and iab-7 regulatory domains that control Abd-B expression in PS11 and PS12. This boundary is composed of multiple functionally redundant elements and has two key activities: it blocks crosstalk between iab-6 and iab-7 and facilitates boundary bypass. Results Here, we have used a structure–function approach to elucidate the biochemical properties and the in vivo activities of a conserved BEN domain protein, Insensitive, that is associated with Fab-7. Our biochemical studies indicate that in addition to the C-terminal BEN DNA-binding domain, Insv has two domains that mediate multimerization: one is a coiled-coil domain in the N-terminus, and the other is next to the BEN domain. These multimerization domains enable Insv to bind simultaneously to two canonical 8-bp recognition motifs, as well as to a ~ 100-bp non-canonical recognition sequence. They also mediate the assembly of higher-order multimers in the presence of DNA. Transgenic proteins lacking the N-terminal coiled-coil domain are compromised for boundary function in vivo. We also show that Insv interacts directly with CP190, a protein previously implicated in the boundary functions of several DNA-binding proteins, including Su(Hw) and dCTCF. While CP190 interaction is required for Insv binding to a subset of sites on polytene chromosomes, it has only a minor role in the boundary activity of Insv in the context of Fab-7. Conclusions The subdivision of eukaryotic chromosomes into discrete topological domains depends upon the pairing of boundary elements. In flies, pairing interactions are specific and typically orientation dependent. They occur in cis between neighboring heterologous boundaries, and in trans between homologous boundaries. One potential mechanism for ensuring pairing-interaction specificity is the use of sequence-specific DNA-binding proteins that can bind simultaneously with two or more recognition sequences. Our studies indicate that Insv can assemble into a multivalent DNA-binding complex and that the N-terminal Insv multimerization domain is critical for boundary function. Electronic supplementary material The online version of this article (10.1186/s13072-018-0249-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anna Fedotova
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Chaevia Clendinen
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Artem Bonchuk
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Vladic Mogila
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Tsutomu Aoki
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Pavel Georgiev
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia.
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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22
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Postika N, Metzler M, Affolter M, Müller M, Schedl P, Georgiev P, Kyrchanova O. Boundaries mediate long-distance interactions between enhancers and promoters in the Drosophila Bithorax complex. PLoS Genet 2018; 14:e1007702. [PMID: 30540750 PMCID: PMC6306242 DOI: 10.1371/journal.pgen.1007702] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 12/26/2018] [Accepted: 11/16/2018] [Indexed: 11/18/2022] Open
Abstract
Drosophila bithorax complex (BX-C) is one of the best model systems for studying the role of boundaries (insulators) in gene regulation. Expression of three homeotic genes, Ubx, abd-A, and Abd-B, is orchestrated by nine parasegment-specific regulatory domains. These domains are flanked by boundary elements, which function to block crosstalk between adjacent domains, ensuring that they can act autonomously. Paradoxically, seven of the BX-C regulatory domains are separated from their gene target by at least one boundary, and must “jump over” the intervening boundaries. To understand the jumping mechanism, the Mcp boundary was replaced with Fab-7 and Fab-8. Mcp is located between the iab-4 and iab-5 domains, and defines the border between the set of regulatory domains controlling abd-A and Abd-B. When Mcp is replaced by Fab-7 or Fab-8, they direct the iab-4 domain (which regulates abd-A) to inappropriately activate Abd-B in abdominal segment A4. For the Fab-8 replacement, ectopic induction was only observed when it was inserted in the same orientation as the endogenous Fab-8 boundary. A similar orientation dependence for bypass activity was observed when Fab-7 was replaced by Fab-8. Thus, boundaries perform two opposite functions in the context of BX-C–they block crosstalk between neighboring regulatory domains, but at the same time actively facilitate long distance communication between the regulatory domains and their respective target genes. Drosophila bithorax complex (BX-C) is one of a few examples demonstrating in vivo role of boundary/insulator elements in organization of independent chromatin domains. BX-C contains three HOX genes, whose parasegment-specific pattern is controlled by cis-regulatory domains flanked by boundary/insulator elements. Since the boundaries ensure autonomy of adjacent domains, the presence of these elements poses a paradox: how do the domains bypass the intervening boundaries and contact their proper regulatory targets? According to the textbook model, BX-C regulatory domains are able to bypass boundaries because they harbor special promoter targeting sequences. However, contrary to this model, we show here that the boundaries themselves play an active role in directing regulatory domains to their appropriate HOX gene promoter.
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Affiliation(s)
- Nikolay Postika
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
| | | | | | | | - Paul Schedl
- Department of Gene Expression Regulation in Development, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- * E-mail: (PG); (OK)
| | - Olga Kyrchanova
- Department of the Control of Genetic Processes, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- * E-mail: (PG); (OK)
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23
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Vermunt MW, Zhang D, Blobel GA. The interdependence of gene-regulatory elements and the 3D genome. J Cell Biol 2018; 218:12-26. [PMID: 30442643 PMCID: PMC6314554 DOI: 10.1083/jcb.201809040] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 10/29/2018] [Accepted: 10/29/2018] [Indexed: 01/12/2023] Open
Abstract
Vermunt et al. discuss the relationship between gene-regulatory elements and nuclear architectural features in transcription. Imaging studies, high-resolution chromatin conformation maps, and genome-wide occupancy data of architectural proteins have revealed that genome topology is tightly intertwined with gene expression. Cross-talk between gene-regulatory elements is often organized within insulated neighborhoods, and regulatory cues that induce transcriptional changes can reshape chromatin folding patterns and gene positioning within the nucleus. The cause–consequence relationship of genome architecture and gene expression is intricate, and its molecular mechanisms are under intense investigation. Here, we review the interdependency of transcription and genome organization with emphasis on enhancer–promoter contacts in gene regulation.
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Affiliation(s)
- Marit W Vermunt
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Di Zhang
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA.,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Gerd A Blobel
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, PA .,Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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24
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The BEN Domain Protein Insensitive Binds to the Fab-7 Chromatin Boundary To Establish Proper Segmental Identity in Drosophila. Genetics 2018; 210:573-585. [PMID: 30082280 DOI: 10.1534/genetics.118.301259] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 07/25/2018] [Indexed: 01/07/2023] Open
Abstract
Boundaries (insulators) in the Drosophila bithorax complex (BX-C) delimit autonomous regulatory domains that orchestrate the parasegment (PS)-specific expression of the BX-C homeotic genes. The Fab-7 boundary separates the iab-6 and iab-7 regulatory domains, which control Abd-B expression in PS11 and PS12, respectively. This boundary is composed of multiple functionally redundant elements and has two key functions: it blocks cross talk between iab-6 and iab-7 and facilitates boundary bypass. Here, we show that two BEN domain protein complexes, Insensitive and Elba, bind to multiple sequences located in the Fab-7 nuclease hypersensitive regions. Two of these sequences are recognized by both Insv and Elba and correspond to a CCAATTGG palindrome. Elba also binds to a related CCAATAAG sequence, while Insv does not. However, the third Insv recognition sequences is ∼100 bp in length and contains the CCAATAAG sequence at one end. Both Insv and Elba are assembled into large complexes (∼420 and ∼265-290 kDa, respectively) in nuclear extracts. Using a sensitized genetic background, we show that the Insv protein is required for Fab-7 boundary function and that PS11 identity is not properly established in insv mutants. This is the first demonstration that a BEN domain protein is important for the functioning of an endogenous fly boundary.
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25
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La Fortezza M, Grigolon G, Cosolo A, Pindyurin A, Breimann L, Blum H, van Steensel B, Classen AK. DamID profiling of dynamic Polycomb-binding sites in Drosophila imaginal disc development and tumorigenesis. Epigenetics Chromatin 2018; 11:27. [PMID: 29871666 PMCID: PMC5987561 DOI: 10.1186/s13072-018-0196-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 05/21/2018] [Indexed: 02/06/2023] Open
Abstract
Background Tracking dynamic protein–chromatin interactions in vivo is key to unravel transcriptional and epigenetic transitions in development and disease. However, limited availability and heterogeneous tissue composition of in vivo source material impose challenges on many experimental approaches. Results Here we adapt cell-type-specific DamID-seq profiling for use in Drosophila imaginal discs and make FLP/FRT-based induction accessible to GAL driver-mediated targeting of specific cell lineages. In a proof-of-principle approach, we utilize ubiquitous DamID expression to describe dynamic transitions of Polycomb-binding sites during wing imaginal disc development and in a scrib tumorigenesis model. We identify Atf3 and Ets21C as novel Polycomb target genes involved in scrib tumorigenesis and suggest that target gene regulation by Atf3 and AP-1 transcription factors, as well as modulation of insulator function, plays crucial roles in dynamic Polycomb-binding at target sites. We establish these findings by DamID-seq analysis of wing imaginal disc samples derived from 10 larvae. Conclusions Our study opens avenues for robust profiling of small cell population in imaginal discs in vivo and provides insights into epigenetic changes underlying transcriptional responses to tumorigenic transformation. Electronic supplementary material The online version of this article (10.1186/s13072-018-0196-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marco La Fortezza
- Faculty of Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2-4, 82152, Planegg, Martinsried, Germany.,Department of Environmental Systems Science, ETH Zurich, Universitätstrasse 16, 8092, Zurich, Switzerland
| | - Giovanna Grigolon
- Faculty of Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2-4, 82152, Planegg, Martinsried, Germany.,Department of Health Sciences and Technology, ETH Zurich, Schorenstrasse 16, 8603, Schwerzenbach, Switzerland
| | - Andrea Cosolo
- Faculty of Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2-4, 82152, Planegg, Martinsried, Germany.,Center for Biological Systems Analysis, Albert-Ludwigs-University Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany
| | - Alexey Pindyurin
- Institute of Molecular and Cellular Biology, Siberian Branch of Russian Academy of Sciences, Acad. Lavrentiev Ave. 8/2, Novosibirsk, 630090, Russia
| | - Laura Breimann
- Faculty of Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2-4, 82152, Planegg, Martinsried, Germany.,Max-Delbrück-Center for Molecular Medicine (MDC), Robert-Rössle-Str. 10, 13092, Berlin, Germany
| | - Helmut Blum
- Laboratory for Functional Genome Analysis, Gene Center Munich, Ludwig-Maximilians-University Munich, Feodor-Lynen-Str. 25, 81377, Munich, Germany
| | - Bas van Steensel
- Division Gene Regulation, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands
| | - Anne-Kathrin Classen
- Faculty of Biology, Ludwig-Maximilians-University Munich, Grosshaderner Strasse 2-4, 82152, Planegg, Martinsried, Germany. .,Center for Biological Systems Analysis, Albert-Ludwigs-University Freiburg, Habsburgerstrasse 49, 79104, Freiburg, Germany.
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26
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Shah FR, Bhat YA, Wani AH. Subnuclear distribution of proteins: Links with genome architecture. Nucleus 2018; 9:42-55. [PMID: 28910577 PMCID: PMC5973252 DOI: 10.1080/19491034.2017.1361578] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 07/25/2017] [Accepted: 07/26/2017] [Indexed: 02/08/2023] Open
Abstract
Metazoan genomes have a hierarchal 3-dimensional (3D) organization scaling from nucleosomes, loops, topologically associating domains (TADs), compartments, to chromosome territories. The 3D organization of genome has been linked with development, differentiation and disease. However, the principles governing the 3D chromatin architecture are just beginning to get unraveled. The nucleus has very high concentration of proteins and these proteins are either diffusely distributed throughout the nucleus, or aggregated in the form of foci/bodies/clusters/speckles or in combination of both. Several evidences suggest that the distribution of proteins within the nuclear space is linked to the organization and function of genome. Here, we describe advances made in understanding the relationship between subnuclear distribution of proteins and genome architecture.
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Affiliation(s)
- Fouziya R. Shah
- Biotechnology, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Younus A. Bhat
- Biotechnology, School of Biological Sciences, University of Kashmir, Srinagar, India
| | - Ajazul H. Wani
- Biotechnology, School of Biological Sciences, University of Kashmir, Srinagar, India
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27
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An Evolutionary Conserved Epigenetic Mark of Polycomb Response Elements Implemented by Trx/MLL/COMPASS. Mol Cell 2017; 63:318-328. [PMID: 27447986 DOI: 10.1016/j.molcel.2016.06.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Revised: 04/07/2016] [Accepted: 06/10/2016] [Indexed: 12/20/2022]
Abstract
Polycomb response elements (PREs) are specific DNA sequences that stably maintain the developmental pattern of gene expression. Drosophila PREs are well characterized, whereas the existence of PREs in mammals remains debated. Accumulating evidence supports a model in which CpG islands recruit Polycomb group (PcG) complexes; however, which subset of CGIs is selected to serve as PREs is unclear. Trithorax (Trx) positively regulates gene expression in Drosophila and co-occupies PREs to antagonize Polycomb-dependent silencing. Here we demonstrate that Trx-dependent H3K4 dimethylation (H3K4me2) marks Drosophila PREs and maintains the developmental expression pattern of nearby genes. Similarly, the mammalian Trx homolog, MLL1, deposits H3K4me2 at CpG-dense regions that could serve as PREs. In the absence of MLL1 and H3K4me2, H3K27me3 levels, a mark of Polycomb repressive complex 2 (PRC2), increase at these loci. By inhibiting PRC2-dependent H3K27me3 in the absence of MLL1, we can rescue expression of these loci, demonstrating a functional balance between MLL1 and PRC2 activities at these sites. Thus, our study provides rules for identifying cell-type-specific functional mammalian PREs within the human genome.
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28
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Three-Dimensional Genome Organization and Function in Drosophila. Genetics 2017; 205:5-24. [PMID: 28049701 PMCID: PMC5223523 DOI: 10.1534/genetics.115.185132] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 10/15/2016] [Indexed: 12/18/2022] Open
Abstract
Understanding how the metazoan genome is used during development and cell differentiation is one of the major challenges in the postgenomic era. Early studies in Drosophila suggested that three-dimensional (3D) chromosome organization plays important regulatory roles in this process and recent technological advances started to reveal connections at the molecular level. Here we will consider general features of the architectural organization of the Drosophila genome, providing historical perspective and insights from recent work. We will compare the linear and spatial segmentation of the fly genome and focus on the two key regulators of genome architecture: insulator components and Polycomb group proteins. With its unique set of genetic tools and a compact, well annotated genome, Drosophila is poised to remain a model system of choice for rapid progress in understanding principles of genome organization and to serve as a proving ground for development of 3D genome-engineering techniques.
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29
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Ciabrelli F, Comoglio F, Fellous S, Bonev B, Ninova M, Szabo Q, Xuéreb A, Klopp C, Aravin A, Paro R, Bantignies F, Cavalli G. Stable Polycomb-dependent transgenerational inheritance of chromatin states in Drosophila. Nat Genet 2017; 49:876-886. [PMID: 28436983 PMCID: PMC5484582 DOI: 10.1038/ng.3848] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 03/27/2017] [Indexed: 12/15/2022]
Abstract
Transgenerational Epigenetic Inheritance (TEI) studies the transmission of alternative functional states through multiple generations in the presence of the same genomic DNA sequence. Very little is known on the principles and the molecular mechanisms governing this type of inheritance. Here, by transiently enhancing 3D chromatin interactions, we established stable and isogenic Drosophila epilines that carry alternative epialleles, defined by differential levels of the Polycomb-dependent H3K27me3 mark. Once established, epialleles can be dominantly transmitted to naïve flies and induce paramutation. Importantly, epilines can be reset to a naïve state by disrupting chromatin interactions. Finally, we show that environmental changes can modulate the expressivity of the epialleles and we extend our paradigm to naturally occurring phenotypes. Our work sheds light on how nuclear organization and Polycomb group proteins contribute to epigenetically inheritable phenotypic variability.
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Affiliation(s)
- Filippo Ciabrelli
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| | - Federico Comoglio
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland
| | | | - Boyan Bonev
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| | - Maria Ninova
- Division of Biology, California Institute of Technology, Pasadena, California, USA
| | - Quentin Szabo
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| | | | - Christophe Klopp
- Unité de Mathématiques et Informatique Appliquées de Toulouse, INRA, Castanet Tolosan, France
| | - Alexei Aravin
- Division of Biology, California Institute of Technology, Pasadena, California, USA
| | - Renato Paro
- Department of Biosystems Science and Engineering, ETH Zurich, Basel, Switzerland.,Faculty of Science, University of Basel, Basel, Switzerland
| | - Frédéric Bantignies
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
| | - Giacomo Cavalli
- Institute of Human Genetics, UMR 9002, CNRS and University of Montpellier, Montpellier, France
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30
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Chetverina D, Fujioka M, Erokhin M, Georgiev P, Jaynes JB, Schedl P. Boundaries of loop domains (insulators): Determinants of chromosome form and function in multicellular eukaryotes. Bioessays 2017; 39. [PMID: 28133765 DOI: 10.1002/bies.201600233] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Chromosomes in multicellular animals are subdivided into a series of looped domains. In addition to being the underlying principle for organizing the chromatin fiber, looping is critical for processes ranging from gene regulation to recombination and repair. The subdivision of chromosomes into looped domains depends upon a special class of architectural elements called boundaries or insulators. These elements are distributed throughout the genome and are ubiquitous building blocks of chromosomes. In this review, we focus on features of boundaries that are critical in determining the topology of the looped domains and their genetic properties. We highlight the properties of fly boundaries that are likely to have an important bearing on the organization of looped domains in vertebrates, and discuss the functional consequences of the observed similarities and differences.
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Affiliation(s)
- Darya Chetverina
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Miki Fujioka
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Maksim Erokhin
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - James B Jaynes
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.,Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
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31
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Buxa MK, Slotman JA, van Royen ME, Paul MW, Houtsmuller AB, Renkawitz R. Insulator speckles associated with long-distance chromatin contacts. Biol Open 2016; 5:1266-74. [PMID: 27464669 PMCID: PMC5051650 DOI: 10.1242/bio.019455] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Nuclear foci of chromatin binding factors are, in many cases, discussed as sites of long-range chromatin interaction in the three-dimensional nuclear space. Insulator binding proteins have been shown to aggregate into insulator bodies, which are large structures not involved in insulation; however, the more diffusely distributed insulator speckles have not been analysed in this respect. Furthermore, insulator binding proteins have been shown to drive binding sites for Polycomb group proteins into Polycomb bodies. Here we find that insulator speckles, marked by the insulator binding protein dCTCF, and Polycomb bodies show differential association with the insulator protein CP190. They differ in number and three-dimensional location with only 26% of the Polycomb bodies overlapping with CP190. By using fluorescence in situ hybridization (FISH) probes to identify long-range interaction (kissing) of the Hox gene clusters Antennapedia complex (ANT-C) and Bithorax complex (BX-C), we found the frequency of interaction to be very low. However, these rare kissing events were associated with insulator speckles at a significantly shorter distance and an increased speckle number. This suggests that insulator speckles are associated with long-distance interaction.
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Affiliation(s)
- Melanie K Buxa
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58, Giessen D35392, Germany
| | - Johan A Slotman
- Department of Pathology, Josephine Nefkens Institute, Erasmus Optical Imaging Centre, Erasmus MC, Postbus 2040, Rotterdam 3000 CA, The Netherlands
| | - Martin E van Royen
- Department of Pathology, Josephine Nefkens Institute, Erasmus Optical Imaging Centre, Erasmus MC, Postbus 2040, Rotterdam 3000 CA, The Netherlands
| | - Maarten W Paul
- Department of Pathology, Josephine Nefkens Institute, Erasmus Optical Imaging Centre, Erasmus MC, Postbus 2040, Rotterdam 3000 CA, The Netherlands
| | - Adriaan B Houtsmuller
- Department of Pathology, Josephine Nefkens Institute, Erasmus Optical Imaging Centre, Erasmus MC, Postbus 2040, Rotterdam 3000 CA, The Netherlands
| | - Rainer Renkawitz
- Institute for Genetics, Justus-Liebig-University, Heinrich-Buff-Ring 58, Giessen D35392, Germany
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32
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Formation of a Polycomb-Domain in the Absence of Strong Polycomb Response Elements. PLoS Genet 2016; 12:e1006200. [PMID: 27466807 PMCID: PMC4965088 DOI: 10.1371/journal.pgen.1006200] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 06/25/2016] [Indexed: 12/24/2022] Open
Abstract
Polycomb group response elements (PREs) in Drosophila are DNA-elements that recruit Polycomb proteins (PcG) to chromatin and regulate gene expression. PREs are easily recognizable in the Drosophila genome as strong peaks of PcG-protein binding over discrete DNA fragments; many small but statistically significant PcG peaks are also observed in PcG domains. Surprisingly, in vivo deletion of the four characterized strong PREs from the PcG regulated invected-engrailed (inv-en) gene complex did not disrupt the formation of the H3K27me3 domain and did not affect inv-en expression in embryos or larvae suggesting the presence of redundant PcG recruitment mechanism. Further, the 3D-structure of the inv-en domain was only minimally altered by the deletion of the strong PREs. A reporter construct containing a 7.5kb en fragment that contains three weak peaks but no large PcG peaks forms an H3K27me3 domain and is PcG-regulated. Our data suggests a model for the recruitment of PcG-complexes to Drosophila genes via interactions with multiple, weak PREs spread throughout an H3K27me3 domain.
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33
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Kyrchanova O, Mogila V, Wolle D, Deshpande G, Parshikov A, Cléard F, Karch F, Schedl P, Georgiev P. Functional Dissection of the Blocking and Bypass Activities of the Fab-8 Boundary in the Drosophila Bithorax Complex. PLoS Genet 2016; 12:e1006188. [PMID: 27428541 PMCID: PMC4948906 DOI: 10.1371/journal.pgen.1006188] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 06/22/2016] [Indexed: 12/16/2022] Open
Abstract
Functionally autonomous regulatory domains direct the parasegment-specific expression of the Drosophila Bithorax complex (BX-C) homeotic genes. Autonomy is conferred by boundary/insulator elements that separate each regulatory domain from its neighbors. For six of the nine parasegment (PS) regulatory domains in the complex, at least one boundary is located between the domain and its target homeotic gene. Consequently, BX-C boundaries must not only block adventitious interactions between neighboring regulatory domains, but also be permissive (bypass) for regulatory interactions between the domains and their gene targets. To elucidate how the BX-C boundaries combine these two contradictory activities, we have used a boundary replacement strategy. We show that a 337 bp fragment spanning the Fab-8 boundary nuclease hypersensitive site and lacking all but 83 bp of the 625 bp Fab-8 PTS (promoter targeting sequence) fully rescues a Fab-7 deletion. It blocks crosstalk between the iab-6 and iab-7 regulatory domains, and has bypass activity that enables the two downstream domains, iab-5 and iab-6, to regulate Abdominal-B (Abd-B) transcription in spite of two intervening boundary elements. Fab-8 has two dCTCF sites and we show that they are necessary both for blocking and bypass activity. However, CTCF sites on their own are not sufficient for bypass. While multimerized dCTCF (or Su(Hw)) sites have blocking activity, they fail to support bypass. Moreover, this bypass defect is not rescued by the full length PTS. Finally, we show that orientation is critical for the proper functioning the Fab-8 replacement. Though the inverted Fab-8 boundary still blocks crosstalk, it disrupts the topology of the Abd-B regulatory domains and does not support bypass. Importantly, altering the orientation of the Fab-8 dCTCF sites is not sufficient to disrupt bypass, indicating that orientation dependence is conferred by other factors. Boundary elements in the Bithorax complex have two seemingly contradictory activities. They must block crosstalk between neighboring regulatory domains, but at the same time be permissive (insulator bypass) for regulatory interactions between the domains and the BX-C homeotic genes. We have used a replacement strategy to investigate how they carry out these two functions. We show that a 337 bp fragment spanning the Fab-8 boundary nuclease hypersensitive site is sufficient to fully rescue a Fab-7 boundary deletion. It blocks crosstalk and supports bypass. As has been observed in transgene assays, blocking activity requires the Fab-8 dCTCF sites, while full bypass activity requires the dCTCF sites plus a small part of PTS. In transgene assays, bypass activity typically depends on the orientation of the two insulators relative to each other. A similar orientation dependence is observed for the Fab-8 replacement in BX-C. When the orientation of the Fab-8 boundary is reversed, bypass activity is lost, while blocking is unaffected. Interestingly, unlike what has been observed in mammals, reversing the orientation of only the Fab-8 dCTCF sites does not affect boundary function. This finding indicates that other Fab-8 factors must play a critical role in determining orientation. Taken together, our findings argue that carrying out the paradoxical functions of the BX-C boundaries does not require any unusual or special properties; rather BX-C boundaries utilize generic blocking and insulator bypass activities that are appropriately adapted to their regulatory context. Thus making them a good model for studying the functional properties of boundaries/insulators in their native setting.
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Affiliation(s)
- Olga Kyrchanova
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- * E-mail: (OK); (PG)
| | - Vladic Mogila
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Daniel Wolle
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Girish Deshpande
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Alexander Parshikov
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Fabienne Cléard
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Francois Karch
- Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Paul Schedl
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Pavel Georgiev
- Department of Genetics, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- * E-mail: (OK); (PG)
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34
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Zolotarev N, Fedotova A, Kyrchanova O, Bonchuk A, Penin AA, Lando AS, Eliseeva IA, Kulakovskiy IV, Maksimenko O, Georgiev P. Architectural proteins Pita, Zw5,and ZIPIC contain homodimerization domain and support specific long-range interactions in Drosophila. Nucleic Acids Res 2016; 44:7228-41. [PMID: 27137890 PMCID: PMC5009728 DOI: 10.1093/nar/gkw371] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 04/23/2016] [Indexed: 12/18/2022] Open
Abstract
According to recent models, as yet poorly studied architectural proteins appear to be required for local regulation of enhancer-promoter interactions, as well as for global chromosome organization. Transcription factors ZIPIC, Pita and Zw5 belong to the class of chromatin insulator proteins and preferentially bind to promoters near the TSS and extensively colocalize with cohesin and condensin complexes. ZIPIC, Pita and Zw5 are structurally similar in containing the N-terminal zinc finger-associated domain (ZAD) and different numbers of C2H2-type zinc fingers at the C-terminus. Here we have shown that the ZAD domains of ZIPIC, Pita and Zw5 form homodimers. In Drosophila transgenic lines, these proteins are able to support long-distance interaction between GAL4 activator and the reporter gene promoter. However, no functional interaction between binding sites for different proteins has been revealed, suggesting that such interactions are highly specific. ZIPIC facilitates long-distance stimulation of the reporter gene by GAL4 activator in yeast model system. Many of the genomic binding sites of ZIPIC, Pita and Zw5 are located at the boundaries of topologically associated domains (TADs). Thus, ZAD-containing zinc-finger proteins can be attributed to the class of architectural proteins.
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Affiliation(s)
- Nikolay Zolotarev
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, Moscow 119334, Russia
| | - Anna Fedotova
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, Moscow 119334, Russia
| | - Olga Kyrchanova
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, Moscow 119334, Russia
| | - Artem Bonchuk
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, Moscow 119334, Russia
| | - Aleksey A Penin
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119991, Russia; Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow 127051 Russia; Department of Genetics, Faculty of Biology, Moscow State University, Moscow 119991, Russia
| | - Andrey S Lando
- Moscow Institute of Physics and Technology (State University), Institutskiy per. 9, Dolgoprudny, Moscow Region 141700, Russia Vavilov Institute of General Genetics, Russian Academy of Sciences, Gubkina str. 3, Moscow, GSP-1, 119991, Russia
| | - Irina A Eliseeva
- Group of Protein Biosynthesis Regulation, Institute of Protein Research, Institutskaya str. 4, Pushchino 142290, Russia
| | - Ivan V Kulakovskiy
- Vavilov Institute of General Genetics, Russian Academy of Sciences, Gubkina str. 3, Moscow, GSP-1, 119991, Russia Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilova str. 32, Moscow, GSP-1, 119991, Russia
| | - Oksana Maksimenko
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, Moscow 119334, Russia
| | - Pavel Georgiev
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, Moscow 119334, Russia
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35
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Abstract
A recent super-resolution imaging study by Boettiger et al. elegantly demonstrates that three epigenetically defined, and functionally disparate, chromatin states have distinct folding characteristics in Drosophila nuclei.
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36
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Fujioka M, Mistry H, Schedl P, Jaynes JB. Determinants of Chromosome Architecture: Insulator Pairing in cis and in trans. PLoS Genet 2016; 12:e1005889. [PMID: 26910731 PMCID: PMC4765946 DOI: 10.1371/journal.pgen.1005889] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 01/30/2016] [Indexed: 12/11/2022] Open
Abstract
The chromosomes of multicellular animals are organized into a series of topologically independent looped domains. This domain organization is critical for the proper utilization and propagation of the genetic information encoded by the chromosome. A special set of architectural elements, called boundaries or insulators, are responsible both for subdividing the chromatin into discrete domains and for determining the topological organization of these domains. Central to the architectural functions of insulators are homologous and heterologous insulator:insulator pairing interactions. The former (pairing between copies of the same insulator) dictates the process of homolog alignment and pairing in trans, while the latter (pairing between different insulators) defines the topology of looped domains in cis. To elucidate the principles governing these architectural functions, we use two insulators, Homie and Nhomie, that flank the Drosophila even skipped locus. We show that homologous insulator interactions in trans, between Homie on one homolog and Homie on the other, or between Nhomie on one homolog and Nhomie on the other, mediate transvection. Critically, these homologous insulator:insulator interactions are orientation-dependent. Consistent with a role in the alignment and pairing of homologs, self-pairing in trans is head-to-head. Head-to-head self-interactions in cis have been reported for other fly insulators, suggesting that this is a general principle of self-pairing. Homie and Nhomie not only pair with themselves, but with each other. Heterologous Homie-Nhomie interactions occur in cis, and we show that they serve to delimit a looped chromosomal domain that contains the even skipped transcription unit and its associated enhancers. The topology of this loop is defined by the heterologous pairing properties of Homie and Nhomie. Instead of being head-to-head, which would generate a circular loop, Homie-Nhomie pairing is head-to-tail. Head-to-tail pairing in cis generates a stem-loop, a configuration much like that observed in classical lampbrush chromosomes. These pairing principles provide a mechanistic underpinning for the observed topologies within and between chromosomes. The chromosomes of multicellular animals are organized into a series of topologically independent looped domains. This domain organization is critical for the proper utilization and propagation of the genetic information encoded by the chromosome. A special set of architectural elements, called boundaries or insulators, are responsible for both subdividing the chromatin fiber into discrete domains, and determining the topological organization of these domains. Central to the architectural functions of insulators are heterologous and homologous insulator:insulator pairing interactions. In Drosophila, the former defines the topology of individual looped domains in cis, while the latter dictates the process of homolog alignment and pairing in trans. Here we use two insulators from the even skipped locus to elucidate the principles governing these two architectural functions. These principles align with several longstanding observations, and resolve a number of conundrums regarding chromosome topology and function.
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Affiliation(s)
- Miki Fujioka
- Deptartment of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
| | - Hemlata Mistry
- Departments of Biology and Biochemistry, Widener University, Chester, Pennsylvania, United States of America
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
- * E-mail: (PS); (JBJ)
| | - James B. Jaynes
- Deptartment of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania, United States of America
- * E-mail: (PS); (JBJ)
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37
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Abstract
Linear chromatin fiber is packed inside the nuclei as a complex three-dimensional structure, and the organization of the chromatin has important roles in the appropriate spatial and temporal regulation of gene expression. To understand how chromatin organizes inside nuclei, and how regulatory proteins physically interact with genes, chromosome conformation capture (3C) technique provides a powerful and sensitive tool to detect both short- and long-range DNA-DNA interaction. Here I describe the 3C technique to detect the DNA-DNA interactions mediated by insulator proteins that are closely related to PcG in Drosophila, which is also broadly applicable to other systems.
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Affiliation(s)
- Hua-Bing Li
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT, 06520, USA.
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38
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Distinct Roles of Chromatin Insulator Proteins in Control of the Drosophila Bithorax Complex. Genetics 2015; 202:601-17. [PMID: 26715665 DOI: 10.1534/genetics.115.179309] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 12/22/2015] [Indexed: 11/18/2022] Open
Abstract
Chromatin insulators are remarkable regulatory elements that can bring distant genomic sites together and block unscheduled enhancer-promoter communications. Insulators act via associated insulator proteins of two classes: sequence-specific DNA binding factors and "bridging" proteins. The latter are required to mediate interactions between distant insulator elements. Chromatin insulators are critical for correct expression of complex loci; however, their mode of action is poorly understood. Here, we use the Drosophila bithorax complex as a model to investigate the roles of the bridging proteins Cp190 and Mod(mdg4). The bithorax complex consists of three evolutionarily conserved homeotic genes Ubx, abd-A, and Abd-B, which specify anterior-posterior identity of the last thoracic and all abdominal segments of the fly. Looking at effects of CTCF, mod(mdg4), and Cp190 mutations on expression of the bithorax complex genes, we provide the first functional evidence that Mod(mdg4) acts in concert with the DNA binding insulator protein CTCF. We find that Mod(mdg4) and Cp190 are not redundant and may have distinct functional properties. We, for the first time, demonstrate that Cp190 is critical for correct regulation of the bithorax complex and show that Cp190 is required at an exceptionally strong Fub insulator to partition the bithorax complex into two topological domains.
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39
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Singh NP, Mishra RK. Specific combinations of boundary element and Polycomb response element are required for the regulation of the Hox genes in Drosophila melanogaster. Mech Dev 2015; 138 Pt 2:141-150. [DOI: 10.1016/j.mod.2015.07.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Revised: 07/30/2015] [Accepted: 07/31/2015] [Indexed: 10/23/2022]
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40
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Kyrchanova O, Mogila V, Wolle D, Magbanua JP, White R, Georgiev P, Schedl P. The boundary paradox in the Bithorax complex. Mech Dev 2015; 138 Pt 2:122-132. [PMID: 26215349 PMCID: PMC4890074 DOI: 10.1016/j.mod.2015.07.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 07/08/2015] [Accepted: 07/09/2015] [Indexed: 02/08/2023]
Abstract
The parasegment-specific expression of the three Drosophila Bithorax complex homeotic genes is orchestrated by nine functionally autonomous regulatory domains. Functional autonomy depends upon special elements called boundaries or insulators that are located between each domain. The boundaries ensure the independent activity of each domain by blocking adventitious interactions with initiators, enhancers and silencers in the neighboring domains. However, this blocking activity poses a regulatory paradox--the Bithorax boundaries are also able to insulate promoters from regulatory interactions with enhancers and silencers and six of the nine Bithorax regulatory domains are separated from their target genes by at least one boundary element. Here we consider several mechanisms that have been suggested for how the Bithorax regulatory domains are able to bypass intervening boundary elements and direct the appropriate parasegment-specific temporal and spatial expression of their target gene.
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Affiliation(s)
- Olga Kyrchanova
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Vladic Mogila
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia; Nikolaev V.A. Sukhomlinsky National University, Department of Biology, Ukraine
| | - Daniel Wolle
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Jose Paolo Magbanua
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Robert White
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | - Pavel Georgiev
- Department of the Control of Genetic Processes, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Paul Schedl
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia; Department of Molecular Biology, Princeton University, Princeton, NJ, USA.
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41
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Functional Requirements for Fab-7 Boundary Activity in the Bithorax Complex. Mol Cell Biol 2015; 35:3739-52. [PMID: 26303531 DOI: 10.1128/mcb.00456-15] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 08/17/2015] [Indexed: 12/23/2022] Open
Abstract
Chromatin boundaries are architectural elements that determine the three-dimensional folding of the chromatin fiber and organize the chromosome into independent units of genetic activity. The Fab-7 boundary from the Drosophila bithorax complex (BX-C) is required for the parasegment-specific expression of the Abd-B gene. We have used a replacement strategy to identify sequences that are necessary and sufficient for Fab-7 boundary function in the BX-C. Fab-7 boundary activity is known to depend on factors that are stage specific, and we describe a novel ∼700-kDa complex, the late boundary complex (LBC), that binds to Fab-7 sequences that have insulator functions in late embryos and adults. We show that the LBC is enriched in nuclear extracts from late, but not early, embryos and that it contains three insulator proteins, GAF, Mod(mdg4), and E(y)2. Its DNA binding properties are unusual in that it requires a minimal sequence of >65 bp; however, other than a GAGA motif, the three Fab-7 LBC recognition elements display few sequence similarities. Finally, we show that mutations which abrogate LBC binding in vitro inactivate the Fab-7 boundary in the BX-C.
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42
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Maksimenko O, Gasanov NB, Georgiev P. Regulatory Elements in Vectors for Efficient Generation of Cell Lines Producing Target Proteins. Acta Naturae 2015; 7:15-26. [PMID: 26483956 PMCID: PMC4610161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
To date, there has been an increasing number of drugs produced in mammalian cell cultures. In order to enhance the expression level and stability of target recombinant proteins in cell cultures, various regulatory elements with poorly studied mechanisms of action are used. In this review, we summarize and discuss the potential mechanisms of action of such regulatory elements.
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Affiliation(s)
- O. Maksimenko
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, 119334, Moscow, Russia
| | - N. B. Gasanov
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, 119334, Moscow, Russia
| | - P. Georgiev
- Institute of Gene Biology, Russian Academy of Sciences, Vavilova str. 34/5, 119334, Moscow, Russia
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43
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Javeed N, Tardi NJ, Maher M, Singari S, Edwards KA. Controlled expression of Drosophila homeobox loci using the Hostile takeover system. Dev Dyn 2015; 244:808-25. [PMID: 25820349 PMCID: PMC4449281 DOI: 10.1002/dvdy.24279] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 03/12/2015] [Accepted: 03/16/2015] [Indexed: 01/16/2023] Open
Abstract
BACKGROUND Hostile takeover (Hto) is a Drosophila protein trapping system that allows the investigator to both induce a gene and tag its product. The Hto transposon carries a GAL4-regulated promoter expressing an exon encoding a FLAG-mCherry tag. Upon expression, the Hto exon can splice to a downstream genomic exon, generating a fusion transcript and tagged protein. RESULTS Using rough-eye phenotypic screens, Hto inserts were recovered at eight homeobox or Pax loci: cut, Drgx/CG34340, Pox neuro, araucan, shaven/D-Pax2, Zn finger homeodomain 2, Sex combs reduced (Scr), and the abdominal-A region. The collection yields diverse misexpression phenotypes. Ectopic Drgx was found to alter the cytoskeleton and cell adhesion in ovary follicle cells. Hto expression of cut, araucan, or shaven gives phenotypes similar to those of the corresponding UAS-cDNA constructs. The cut and Pox neuro phenotypes are suppressed by the corresponding RNAi constructs. The Scr and abdominal-A inserts do not make fusion proteins, but may act by chromatin- or RNA-based mechanisms. CONCLUSIONS Hto can effectively express tagged homeodomain proteins from their endogenous loci; the Minos vector allows inserts to be obtained even in transposon cold-spots. Hto screens may recover homeobox genes at high rates because they are particularly sensitive to misexpression.
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Affiliation(s)
- Naureen Javeed
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Nicholas J. Tardi
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Maggie Maher
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Swetha Singari
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
| | - Kevin A. Edwards
- School of Biological Sciences, Illinois State University, Normal, IL 61790, USA
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44
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Kyrchanova OV, Georgiev PG. The bithorax complex of Drosophila melanogaster as a model for studying specific long-distance interactions between enhancers and promoters. RUSS J GENET+ 2015. [DOI: 10.1134/s1022795415050038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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45
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Cubeñas-Potts C, Corces VG. Architectural proteins, transcription, and the three-dimensional organization of the genome. FEBS Lett 2015; 589:2923-30. [PMID: 26008126 DOI: 10.1016/j.febslet.2015.05.025] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 05/07/2015] [Accepted: 05/09/2015] [Indexed: 12/20/2022]
Abstract
Architectural proteins mediate interactions between distant sequences in the genome. Two well-characterized functions of architectural protein interactions include the tethering of enhancers to promoters and bringing together Polycomb-containing sites to facilitate silencing. The nature of which sequences interact genome-wide appears to be determined by the orientation of the architectural protein binding sites as well as the number and identity of architectural proteins present. Ultimately, long range chromatin interactions result in the formation of loops within the chromatin fiber. In this review, we discuss data suggesting that architectural proteins mediate long range chromatin interactions that both facilitate and hinder neighboring interactions, compartmentalizing the genome into regions of highly interacting chromatin domains.
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Affiliation(s)
- Caelin Cubeñas-Potts
- Department of Biology, Emory University, 1510 Clifton Rd NE, Atlanta, GA 30322, USA
| | - Victor G Corces
- Department of Biology, Emory University, 1510 Clifton Rd NE, Atlanta, GA 30322, USA.
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Razin SV, Borunova VV, Iarovaia OV, Vassetzky YS. Nuclear matrix and structural and functional compartmentalization of the eucaryotic cell nucleus. BIOCHEMISTRY (MOSCOW) 2015; 79:608-18. [PMID: 25108324 DOI: 10.1134/s0006297914070037] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Becoming popular at the end of the 20th century, the concept of the nuclear matrix implies the existence of a nuclear skeleton that organizes functional elements in the cell nucleus. This review presents a critical analysis of the results obtained in the study of nuclear matrix in the light of current views on the organization of the cell nucleus. Numerous studies of nuclear matrix have failed to provide evidence of the existence of such a structure. Moreover, the existence of a filamentous structure that supports the nuclear compartmentalization appears to be unnecessary, since this function is performed by the folded genome itself.
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Affiliation(s)
- S V Razin
- Institute of Gene Biology, Russian Academy of Sciences, Moscow, 119334, Russia.
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Widespread rearrangement of 3D chromatin organization underlies polycomb-mediated stress-induced silencing. Mol Cell 2015; 58:216-31. [PMID: 25818644 DOI: 10.1016/j.molcel.2015.02.023] [Citation(s) in RCA: 219] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/09/2015] [Accepted: 02/19/2015] [Indexed: 12/28/2022]
Abstract
Chromosomes of metazoan organisms are partitioned in the interphase nucleus into discrete topologically associating domains (TADs). Borders between TADs are formed in regions containing active genes and clusters of architectural protein binding sites. The transcription of most genes is repressed after temperature stress in Drosophila. Here we show that temperature stress induces relocalization of architectural proteins from TAD borders to inside TADs, and this is accompanied by a dramatic rearrangement in the 3D organization of the nucleus. TAD border strength declines, allowing for an increase in long-distance inter-TAD interactions. Similar but quantitatively weaker effects are observed upon inhibition of transcription or depletion of individual architectural proteins. Heat shock-induced inter-TAD interactions result in increased contacts among enhancers and promoters of silenced genes, which recruit Pc and form Pc bodies in the nucleolus. These results suggest that the TAD organization of metazoan genomes is plastic and can be reconfigured quickly.
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48
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Gavrilov AA, Razin SV. Compartmentalization of the cell nucleus and spatial organization of the genome. Mol Biol 2015. [DOI: 10.1134/s0026893315010033] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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49
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Chromatin-Driven Behavior of Topologically Associating Domains. J Mol Biol 2015; 427:608-25. [DOI: 10.1016/j.jmb.2014.09.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/17/2014] [Accepted: 09/23/2014] [Indexed: 12/19/2022]
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50
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Ulianov SV, Gavrilov AA, Razin SV. Nuclear Compartments, Genome Folding, and Enhancer-Promoter Communication. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:183-244. [DOI: 10.1016/bs.ircmb.2014.11.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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