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Owen JA, Osmanović D, Mirny L. Design principles of 3D epigenetic memory systems. Science 2023; 382:eadg3053. [PMID: 37972190 PMCID: PMC11075759 DOI: 10.1126/science.adg3053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 09/28/2023] [Indexed: 11/19/2023]
Abstract
Cells remember their identities, in part, by using epigenetic marks-chemical modifications placed along the genome. How can mark patterns remain stable over cell generations despite their constant erosion by replication and other processes? We developed a theoretical model that reveals that three-dimensional (3D) genome organization can stabilize epigenetic memory as long as (i) there is a large density difference between chromatin compartments, (ii) modifying "reader-writer" enzymes spread marks in three dimensions, and (iii) the enzymes are limited in abundance relative to their histone substrates. Analogous to an associative memory that encodes memory in neuronal connectivity, mark patterns are encoded in a 3D network of chromosomal contacts. Our model provides a unified account of diverse observations and reveals a key role of 3D genome organization in epigenetic memory.
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Affiliation(s)
- Jeremy A. Owen
- Department of Physics, Massachusetts Institute of Technology; Cambridge, USA
| | - Dino Osmanović
- Department of Mechanical and Aeronautical Engineering, UCLA; Los Angeles, USA
| | - Leonid Mirny
- Department of Physics, Massachusetts Institute of Technology; Cambridge, USA
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Örkenby L, Skog S, Ekman H, Gozzo A, Kugelberg U, Ramesh R, Magadi S, Zambanini G, Nordin A, Cantú C, Nätt D, Öst A. Stress-sensitive dynamics of miRNAs and Elba1 in Drosophila embryogenesis. Mol Syst Biol 2023; 19:e11148. [PMID: 36938679 PMCID: PMC10167479 DOI: 10.15252/msb.202211148] [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: 05/29/2022] [Revised: 02/15/2023] [Accepted: 02/23/2023] [Indexed: 03/21/2023] Open
Abstract
Early-life stress can result in life-long effects that impact adult health and disease risk, but little is known about how such programming is established and maintained. Here, we show that such epigenetic memories can be initiated in the Drosophila embryo before the major wave of zygotic transcription, and higher-order chromatin structures are established. An early short heat shock results in elevated levels of maternal miRNA and reduced levels of a subgroup of zygotic genes in stage 5 embryos. Using a Dicer-1 mutant, we show that the stress-induced decrease in one of these genes, the insulator-binding factor Elba1, is dependent on functional miRNA biogenesis. Reduction in Elba1 correlates with the upregulation of early developmental genes and promotes a sustained weakening of heterochromatin in the adult fly as indicated by an increased expression of the PEV wm4h reporter. We propose that maternal miRNAs, retained in response to an early embryonic heat shock, shape the subsequent de novo heterochromatin establishment that occurs during early development via direct or indirect regulation of some of the earliest expressed genes, including Elba1.
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Affiliation(s)
- Lovisa Örkenby
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Signe Skog
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Helen Ekman
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Alessandro Gozzo
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Unn Kugelberg
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Rashmi Ramesh
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Srivathsa Magadi
- Division of Neurobiology (NEURO), Linköping University, Linköping, Sweden
| | - Gianluca Zambanini
- Division of Molecular Medicine and Virology (MMV), Linköping University, Linköping, Sweden
| | - Anna Nordin
- Division of Molecular Medicine and Virology (MMV), Linköping University, Linköping, Sweden
| | - Claudio Cantú
- Division of Molecular Medicine and Virology (MMV), Linköping University, Linköping, Sweden
| | - Daniel Nätt
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Anita Öst
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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Camelo-Júnior AE, Ferreira AWC, Andrade IM, Mayo SJ, Nollet F, Silva JL, Barros MC, Fraga E, Pessoa EM. Species delimitation in the Trichocentrum cepula (Oncidiinae, Orchidaceae) complex: a multidisciplinary approach. SYST BIODIVERS 2022. [DOI: 10.1080/14772000.2022.2099478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- Antonio E. Camelo-Júnior
- Programa de Pós-Graduação em Biodiversidade, Ambiente e Saúde, Universidade Estadual do Maranhão, Campus Caxias, 65.604-380, Caxias, Maranhão, Brazil
| | | | - Ivanilza M. Andrade
- Núcleo de Pesquisa em Biodiversidade e Biotecnologia, Biotec, Campus de Parnaíba, Universidade Federal do Delta do Piauí, Parnaíba, Piauí, Brazil
| | - Simon J. Mayo
- Royal Botanic Gardens, Kew, Richmond TW9 3AE, Surrey, UK
| | - Felipe Nollet
- Departamento de Biologia, Programa de Pós-Graduação em Botânica, Universidade Federal Rural de Pernambuco, Dois Irmãos, Recife, 52171–900, Pernambuco, Brazil
| | - José L. Silva
- Departamento de Ciências Biológicas, Universidade Federal da Paraíba Centro de Ciências Agrárias, Campus II, Areia, 58397-000, Paraíba, Brazil
| | - Maria C. Barros
- Programa de Pós-Graduação em Biodiversidade, Ambiente e Saúde, Universidade Estadual do Maranhão, Campus Caxias, 65.604-380, Caxias, Maranhão, Brazil
| | - Elmary Fraga
- Programa de Pós-Graduação em Biodiversidade, Ambiente e Saúde, Universidade Estadual do Maranhão, Campus Caxias, 65.604-380, Caxias, Maranhão, Brazil
| | - Edlley M. Pessoa
- Programa de Pós-Graduação em Biodiversidade, Ambiente e Saúde, Universidade Estadual do Maranhão, Campus Caxias, 65.604-380, Caxias, Maranhão, Brazil
- Departamento de Botânica e Ecologia, Universidade Federal do Mato Grosso, Cuiabá, 78060-900, Mato Grosso, Brazil
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Bughio FJ, Maggert KA. Live analysis of position-effect variegation in Drosophila reveals different modes of action for HP1a and Su(var)3-9. Proc Natl Acad Sci U S A 2022; 119:e2118796119. [PMID: 35704756 PMCID: PMC9231485 DOI: 10.1073/pnas.2118796119] [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: 10/13/2021] [Accepted: 04/19/2022] [Indexed: 11/18/2022] Open
Abstract
Position-effect variegation (PEV) results from the juxtaposition of euchromatic and heterochromatic components of eukaryotic genomes, silencing genes near the new euchromatin/heterochromatin junctions. Silencing is itself heritable through S phase, giving rise to distinctive random patterns of cell clones expressing the genes intermixed with clones in which the genes are silenced. Much of what we know about epigenetic inheritance in the soma stems from work on PEV aimed at identifying the components of the silencing machinery and its mechanism of inheritance. The roles of two central gene activities-the Su(var)3-9-encoded histone H3-lysine-9 methyltransferase and the Su(var)205-encoded methyl-H3-lysine-9 binding protein heterochromatin protein 1 (HP1a)-have been inferred from terminal phenotypes, leaving considerable gaps in understanding of how PEV behaves through development. Here, we investigate the PEV phenotypes of Su(var)3-9 and Su(var)205 mutations in live developing tissues. We discovered that mutation in Su(var)205 compromises the initial establishment of PEV in early embryogenesis. Later gains of heterochromatin-induced gene silencing are possible but are unstable and lost rapidly. In contrast, a strain with mutation in Su(var)3-9 exhibits robust silencing early in development but fails to maintain it through subsequent cell divisions. Our analyses show that, while the terminal phenotypes of these mutations may appear identical, they have arrived at them through different developmental trajectories. We discuss how our findings expand and clarify existing models for epigenetic inheritance of heterochromatin-induced gene silencing.
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Affiliation(s)
- Farah J. Bughio
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, AZ 85724
| | - Keith A. Maggert
- Department of Cellular and Molecular Medicine, University of Arizona Cancer Center, University of Arizona, Tucson, AZ 85724
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Shaban K, Sauty SM, Yankulov K. Variation, Variegation and Heritable Gene Repression in S. cerevisiae. Front Genet 2021; 12:630506. [PMID: 33747046 PMCID: PMC7970126 DOI: 10.3389/fgene.2021.630506] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 02/08/2021] [Indexed: 11/13/2022] Open
Abstract
Phenotypic heterogeneity provides growth advantages for a population upon changes of the environment. In S. cerevisiae, such heterogeneity has been observed as "on/off" states in the expression of individual genes in individual cells. These variations can persist for a limited or extended number of mitotic divisions. Such traits are known to be mediated by heritable chromatin structures, by the mitotic transmission of transcription factors involved in gene regulatory circuits or by the cytoplasmic partition of prions or other unstructured proteins. The significance of such epigenetic diversity is obvious, however, we have limited insight into the mechanisms that generate it. In this review, we summarize the current knowledge of epigenetically maintained heterogeneity of gene expression and point out similarities and converging points between different mechanisms. We discuss how the sharing of limiting repression or activation factors can contribute to cell-to-cell variations in gene expression and to the coordination between short- and long- term epigenetic strategies. Finally, we discuss the implications of such variations and strategies in adaptation and aging.
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Affiliation(s)
- Kholoud Shaban
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Safia Mahabub Sauty
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Krassimir Yankulov
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
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