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Simon L, Probst AV. Maintenance and dynamic reprogramming of chromatin organization during development. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:657-670. [PMID: 36700345 DOI: 10.1111/tpj.16119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 01/20/2023] [Accepted: 01/23/2023] [Indexed: 06/17/2023]
Abstract
Controlled transcription of genes is critical for cell differentiation and development. Gene expression regulation therefore involves a multilayered control from nucleosome composition in histone variants and their post-translational modifications to higher-order folding of chromatin fibers and chromatin interactions in nuclear space. Recent technological advances have allowed gaining insight into these mechanisms, the interplay between local and higher-order chromatin organization, and the dynamic changes that occur during stress response and developmental transitions. In this review, we will discuss chromatin organization from the nucleosome to its three-dimensional structure in the nucleus, and consider how these different layers of organization are maintained during the cell cycle or rapidly reprogrammed during development.
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Affiliation(s)
- Lauriane Simon
- iGReD, CNRS, Inserm, Université Clermont Auvergne, 63000, Clermont-Ferrand, France
| | - Aline V Probst
- iGReD, CNRS, Inserm, Université Clermont Auvergne, 63000, Clermont-Ferrand, France
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2
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Gao Z, He Y. Molecular epigenetic understanding of winter memory in Arabidopsis. PLANT PHYSIOLOGY 2024; 194:1952-1961. [PMID: 37950890 DOI: 10.1093/plphys/kiad597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 10/13/2023] [Accepted: 11/03/2023] [Indexed: 11/13/2023]
Affiliation(s)
- Zheng Gao
- National Key Laboratory of Wheat Improvement, Peking-Tsinghua Center for Life Sciences, School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
| | - Yuehui He
- National Key Laboratory of Wheat Improvement, Peking-Tsinghua Center for Life Sciences, School of Advanced Agricultural Sciences, Peking University, Beijing 100871, China
- Peking University Institute of Advanced Agricultural Sciences, Shandong Laboratory of Advanced Agricultural Sciences in Weifang, Shandong 261325, China
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3
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Nielsen M, Menon G, Zhao Y, Mateo-Bonmati E, Wolff P, Zhou S, Howard M, Dean C. COOLAIR and PRC2 function in parallel to silence FLC during vernalization. Proc Natl Acad Sci U S A 2024; 121:e2311474121. [PMID: 38236739 PMCID: PMC10823242 DOI: 10.1073/pnas.2311474121] [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: 07/13/2023] [Accepted: 12/11/2023] [Indexed: 01/23/2024] Open
Abstract
Noncoding transcription induces chromatin changes that can mediate environmental responsiveness, but the causes and consequences of these mechanisms are still unclear. Here, we investigate how antisense transcription (termed COOLAIR) interfaces with Polycomb Repressive Complex 2 (PRC2) silencing during winter-induced epigenetic regulation of Arabidopsis FLOWERING LOCUS C (FLC). We use genetic and chromatin analyses on lines ineffective or hyperactive for the antisense pathway in combination with computational modeling to define the mechanisms underlying FLC repression. Our results show that FLC is silenced through pathways that function with different dynamics: a COOLAIR transcription-mediated pathway capable of fast response and in parallel a slow PRC2 switching mechanism that maintains each allele in an epigenetically silenced state. Components of both the COOLAIR and PRC2 pathways are regulated by a common transcriptional regulator (NTL8), which accumulates by reduced dilution due to slow growth at low temperature. The parallel activities of the regulatory steps, and their control by temperature-dependent growth dynamics, create a flexible system for registering widely fluctuating natural temperature conditions that change year on year, and yet ensure robust epigenetic silencing of FLC.
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Affiliation(s)
- Mathias Nielsen
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Govind Menon
- Computational and Systems Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Yusheng Zhao
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Eduardo Mateo-Bonmati
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Philip Wolff
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Shaoli Zhou
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Martin Howard
- Computational and Systems Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
| | - Caroline Dean
- Department of Cell and Developmental Biology, John Innes Centre, NorwichNR4 7UH, United Kingdom
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Zhu P, Schon M, Questa J, Nodine M, Dean C. Causal role of a promoter polymorphism in natural variation of the Arabidopsis floral repressor gene FLC. Curr Biol 2023; 33:4381-4391.e3. [PMID: 37729909 DOI: 10.1016/j.cub.2023.08.079] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 07/06/2023] [Accepted: 08/25/2023] [Indexed: 09/22/2023]
Abstract
Noncoding polymorphism frequently associates with phenotypic variation, but causation and mechanism are rarely established. Noncoding single-nucleotide polymorphisms (SNPs) characterize the major haplotypes of the Arabidopsis thaliana floral repressor gene FLOWERING LOCUS C (FLC). This noncoding polymorphism generates a range of FLC expression levels, determining the requirement for and the response to winter cold. The major adaptive determinant of these FLC haplotypes was shown to be the autumnal levels of FLC expression. Here, we investigate how noncoding SNPs influence FLC transcriptional output. We identify an upstream transcription start site (uTSS) cluster at FLC, whose usage is increased by an A variant at the promoter SNP-230. This variant is present in relatively few Arabidopsis accessions, with the majority containing G at this site. We demonstrate a causal role for the A variant at -230 in reduced FLC transcriptional output. The G variant upregulates FLC expression redundantly with the major transcriptional activator FRIGIDA (FRI). We demonstrate an additive interaction of SNP-230 with an intronic SNP+259, which also differentially influences uTSS usage. Combinatorial interactions between noncoding SNPs and transcriptional activators thus generate quantitative variation in FLC transcription that has facilitated the adaptation of Arabidopsis accessions to distinct climates.
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Affiliation(s)
- Pan Zhu
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Michael Schon
- Laboratory of Molecular Biology, Wageningen University, Wageningen 6708 PB, the Netherlands; Gregor Mendel Institute, Vienna Biocenter, Vienna 1030, Austria
| | - Julia Questa
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Michael Nodine
- Laboratory of Molecular Biology, Wageningen University, Wageningen 6708 PB, the Netherlands; Gregor Mendel Institute, Vienna Biocenter, Vienna 1030, Austria
| | - Caroline Dean
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
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5
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Franco-Echevarría E, Nielsen M, Schulten A, Cheema J, Morgan TE, Bienz M, Dean C. Distinct accessory roles of Arabidopsis VEL proteins in Polycomb silencing. Genes Dev 2023; 37:801-817. [PMID: 37734835 PMCID: PMC7615239 DOI: 10.1101/gad.350814.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 08/31/2023] [Indexed: 09/23/2023]
Abstract
Polycomb repressive complex 2 (PRC2) mediates epigenetic silencing of target genes in animals and plants. In Arabidopsis, PRC2 is required for the cold-induced epigenetic silencing of the FLC floral repressor locus to align flowering with spring. During this process, PRC2 relies on VEL accessory factors, including the constitutively expressed VRN5 and the cold-induced VIN3. The VEL proteins are physically associated with PRC2, but their individual functions remain unclear. Here, we show an intimate association between recombinant VRN5 and multiple components within a reconstituted PRC2, dependent on a compact conformation of VRN5 central domains. Key residues mediating this compact conformation are conserved among VRN5 orthologs across the plant kingdom. In contrast, VIN3 interacts with VAL1, a transcriptional repressor that binds directly to FLC These associations differentially affect their role in H3K27me deposition: Both proteins are required for H3K27me3, but only VRN5 is necessary for H3K27me2. Although originally defined as vernalization regulators, VIN3 and VRN5 coassociate with many targets in the Arabidopsis genome that are modified with H3K27me3. Our work therefore reveals the distinct accessory roles for VEL proteins in conferring cold-induced silencing on FLC, with broad relevance for PRC2 targets generally.
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Affiliation(s)
- Elsa Franco-Echevarría
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Mathias Nielsen
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Anna Schulten
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Jitender Cheema
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
| | - Tomos E Morgan
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom
| | - Mariann Bienz
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom;
| | - Caroline Dean
- Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 0QH, United Kingdom;
- John Innes Centre, Norwich Research Park, Norwich NR4 7UH, United Kingdom
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Field S, Jang GJ, Dean C, Strader LC, Rhee SY. Plants use molecular mechanisms mediated by biomolecular condensates to integrate environmental cues with development. THE PLANT CELL 2023; 35:3173-3186. [PMID: 36879427 PMCID: PMC10473230 DOI: 10.1093/plcell/koad062] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 02/01/2023] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
This review highlights recent literature on biomolecular condensates in plant development and discusses challenges for fully dissecting their functional roles. Plant developmental biology has been inundated with descriptive examples of biomolecular condensate formation, but it is only recently that mechanistic understanding has been forthcoming. Here, we discuss recent examples of potential roles biomolecular condensates play at different stages of the plant life cycle. We group these examples based on putative molecular functions, including sequestering interacting components, enhancing dwell time, and interacting with cytoplasmic biophysical properties in response to environmental change. We explore how these mechanisms could modulate plant development in response to environmental inputs and discuss challenges and opportunities for further research into deciphering molecular mechanisms to better understand the diverse roles that biomolecular condensates exert on life.
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Affiliation(s)
- Sterling Field
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Geng-Jen Jang
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Caroline Dean
- Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
| | - Lucia C Strader
- Department of Biology, Duke University, Durham, NC 27708, USA
| | - Seung Y Rhee
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
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Surya W, Yong CPY, Tyagi A, Bhushan S, Torres J. Anomalous Oligomerization Behavior of E. coli Aquaporin Z in Detergent and in Nanodiscs. Int J Mol Sci 2023; 24:ijms24098098. [PMID: 37175807 PMCID: PMC10178869 DOI: 10.3390/ijms24098098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 04/28/2023] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
Aquaporins are tetrameric integral membrane proteins that act as water channels, and can also permeabilize membranes to other solutes. The monomer appears to be the functional form despite all aquaporins being organized as tetramers, which therefore must provide a clear functional advantage. In addition to this quaternary organization, some aquaporins can act as adhesion molecules in membrane junctions, when tetramers located in opposing membranes interact via their extracellular domains. These stacked forms have been observed in a range of aquaporins, whether using lipidic membrane environments, in electron crystallography, or using detergent micelles, in single-particle cryo-electron microscopy (cryo-EM). In the latter technique, structural studies can be performed when the aquaporin is reconstituted into nanodiscs of lipids that are surrounded by a protein scaffold. During attempts to study E. coli Aquaporin Z (AqpZ), we have found that in some conditions these nanodiscs tend to form filaments that appear to be either thicker head-to-tail or thinner side-to-side stacks of nanodiscs. Nanodisc oligomerization was observed using orthogonal analytical techniques analytical ultra-centrifugation and mass photometry, although the nature of the oligomers (head-to-tail or side-to-side) could not be determined. Using the latter technique, the AqpZ tetramer itself formed oligomers of increasing size when solubilized only in detergent, which is consistent with multiple stacking of AqpZ tetramers. We observed images consistent with both of these filaments in negative staining EM conditions, but only thicker filaments in cryo-EM conditions. We hypothesize that the apparent nanodisc side-to-side arrangement that can only be visualized in negative staining conditions is related to artifacts due to the sample preparation. Filaments of any kind were not observed in EM when nanodiscs did not contain AqpZ, or after addition of detergent into the nanodisc cryo-EM preparation, at concentrations that did not disrupt nanodisc formation. To our knowledge, these filaments have not been observed in nanodiscs preparations of other membrane proteins. AqpZ, like other aquaporins has a charge asymmetry between the cytoplasmic (more positive) and the extracellular sides, which may explain the likely head-to-tail stacking observed, both in nanodisc preparations and also in detergent micelles.
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Affiliation(s)
- Wahyu Surya
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Clare Pei Yii Yong
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Anu Tyagi
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Shashi Bhushan
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
| | - Jaume Torres
- School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Singapore
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