| 1. |
- Derkacheva, Maria, et al.
(författare)
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Arabidopsis MSI1 connects LHP1 to PRC2 complexes
- 2013
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Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 32, s. 2073-2085
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Tidskriftsartikel (refereegranskat)abstract
- Polycomb group (PcG) proteins form essential epigenetic memory systems for controlling gene expression during development in plants and animals. However, the mechanism of plant PcG protein functions remains poorly understood. Here, we probed the composition and function of plant Polycomb repressive complex 2 (PRC2). This work established the fact that all known plant PRC2 complexes contain MSI1, a homologue of Drosophila p55. While p55 is not essential for the in vitro enzymatic activity of PRC2, plant MSI1 was required for the functions of the EMBRYONIC FLOWER and the VERNALIZATION PRC2 complexes including trimethylation of histone H3 Lys27 (H3K27) at the target chromatin, as well as gene repression and establishment of competence to flower. We found that MSI1 serves to link PRC2 to LIKE HETEROCHROMATIN PROTEIN 1 (LHP1), a protein that binds H3K27me3 in vitro and in vivo and is required for a functional plant PcG system. The LHP1-MSI1 interaction forms a positive feedback loop to recruit PRC2 to chromatin that carries H3K27me3. Consequently, this can provide a mechanism for the faithful inheritance of local epigenetic information through replication.
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| 2. |
- Derkacheva, Maria, et al.
(författare)
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H2A deubiquitinases UBP12/13 are part of the Arabidopsis polycomb group protein system
- 2016
-
Ingår i: Nature plants. - 2055-026X .- 2055-0278. ; 2:9
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Tidskriftsartikel (refereegranskat)abstract
- Polycomb group (PcG) proteins form an epigenetic memory system in plants and animals, but interacting proteins are poorly known in plants. Here, we have identified Arabidopsis UBIQUITIN SPECIFIC PROTEASES (USP; UBP in plant and yeasts) 12 and 13 as partners of the plant-specific PcG protein LIKE HETEROCHROMATIN PROTEIN 1 (LHP1). UBP12 binds to chromatin of PcG target genes and is required for histone H3 lysine 27 trimethylation and repression of a subset of PcG target genes. Plants lacking UBP12 and UBP13 developed autonomous endosperm in the absence of fertilization. We have identified UBP12 and UBP13 as new proteins in the plant PcG regulatory network. UBP12 and UBP13 belong to an ancient gene family and represent plant homologues of metazoan USP7. We have found that Drosophila USP7 shares a function in heterochromatic gene repression with UBP12/13 and their homologue UBP26. In summary, we demonstrate that USP7-like proteins are essential for gene silencing in diverse genomic contexts.
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| 3. |
- Derkacheva, Maria, et al.
(författare)
-
H2A deubiquitinases UBP12/13 are part of the Arabidopsis polycomb group protein system
- 2016
-
Ingår i: Nature Plants. - : Springer Science and Business Media LLC. - 2055-026X .- 2055-0278. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- Polycomb group (PcG) proteins form an epigenetic memory system in plants and animals, but interacting proteins are poorly known in plants. Here, we have identified Arabidopsis UBIQUITIN SPECIFIC PROTEASES (USP; UBP in plant and yeasts) 12 and 13 as partners of the plant-specific PcG protein LIKE HETEROCHROMATIN PROTEIN 1 (LHP1). UBP12 binds to chromatin of PcG target genes and is required for histone H3 lysine 27 trimethylation and repression of a subset of PcG target genes. Plants lacking UBP12 and UBP13 developed autonomous endosperm in the absence of fertilization. We have identified UBP12 and UBP13 as new proteins in the plant PcG regulatory network. UBP12 and UBP13 belong to an ancient gene family and represent plant homologues of metazoan USP7. We have found that Drosophila USP7 shares a function in heterochromatic gene repression with UBP12/13 and their homologue UBP26. In summary, we demonstrate that USP7-like proteins are essential for gene silencing in diverse genomic contexts.
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| 4. |
- Hennigs, Lars, et al.
(författare)
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PRC2 Represses Hormone-Induced Somatic Embryogenesis in Vegetative Tissue of Arabidopsis thaliana
- 2017
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Many plant cells can be reprogrammed into a pluripotent state that allows ectopic organ development. Inducing totipotent states to stimulate somatic embryo ( SE) development is, however, challenging due to insufficient understanding of molecular barriers that prevent somatic cell dedifferentiation. Here we show that Polycomb repressive complex 2 (PRC2) activity imposes a barrier to hormone-mediated transcriptional reprogramming towards somatic embryogenesis in vegetative tissue of Arabidopsis thaliana. We identify factors that enable SE development in PRC2-depleted shoot and root tissue and demonstrate that the establishment of embryogenic potential is marked by ectopic co-activation of crucial developmental regulators that specify shoot, root and embryo identity. Using inducible activation of PRC2 in PRC2-depleted cells, we demonstrate that transient reduction of PRC2 activity is sufficient for SE formation. We suggest that modulation of PRC2 activity in plant vegetative tissue combined with targeted activation of developmental pathways will open possibilities for novel approaches to cell reprogramming.
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| 5. |
- Mozgova, Iva, et al.
(författare)
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Chromatin assembly factor CAF-1 represses priming of plant defence response genes
- 2015
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Ingår i: Nature Plants. - 2055-026X .- 2055-0278. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- Plants have evolved efficient defence systems against pathogens that often rely on specific transcriptional responses. Priming is part of the defence syndrome, by establishing a hypersensitive state of defence genes such as after a first encounter with a pathogen. Because activation of defence responses has a fitness cost, priming must be tightly controlled to prevent spurious activation of defence. However, mechanisms that repress defence gene priming are poorly understood. Here, we show that the histone chaperone CAF-1 is required to establish a repressed chromatin state at defence genes. Absence of CAF-1 results in spurious activation of a salicylic acid-dependent pathogen defence response in plants grown under non-sterile conditions. Chromatin at defence response genes in CAF-1 mutants under non-inductive (sterile) conditions is marked by low nucleosome occupancy and high H3K4me3 at transcription start sites, resembling chromatin in primed wild-type plants. We conclude that CAF-1-mediated chromatin assembly prevents the establishment of a primed state that may under standard non-sterile growth conditions result in spurious activation of SA-dependent defence responses and consequential reduction of plant vigour.
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| 6. |
- Mozgova, Iva, et al.
(författare)
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DNA-sequence-specific erasers of epigenetic memory
- 2016
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 48, s. 591-592
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Annan publikation (refereegranskat)abstract
- How epigenetic regulators find their specific targets remains a challenging question. Two parallel studies show that REF6, a plant H3K27me3 demethylase, binds a specific DNA motif via its zinc-finger domains and recruits the SWI/SNF-type ATPase BRAHMA, demonstrating a sequence-specific recruitment mechanism for a chromatinmodifying complex.
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| 7. |
- Mozgova, Iva, et al.
(författare)
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Keeping the gate closed: functions of the polycomb repressive complex PRC2 in development
- 2015
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Ingår i: Plant Journal. - : Wiley. - 0960-7412 .- 1365-313X. ; 83, s. 121-132
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Tidskriftsartikel (refereegranskat)abstract
- Plant ontogeny relies on the correct timing and sequence of transitions between individual developmental phases. These are specified by gene expression patterns that are established by the balanced action of activators and repressors. Polycomb repressive complexes (PRCs) represent an evolutionarily conserved system of epigenetic gene repression that governs the establishment and maintenance of cell, tissue and organ identity, contributing to the correct execution of the developmental programs. PRC2 is a four-subunit histone methyltransferase complex that catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3), which contributes to the change of chromatin structure and long-lasting gene repression. Here, we review the composition and molecular function of the different known PRC2 complexes in plants, and focus on the role of PRC2 in mediating the establishment of different developmental phases and transitions between them.
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| 8. |
- Mozgova, Iva, et al.
(författare)
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The many faces of plant chromatin: Meeting summary of the 4th European workshop on plant chromatin 2015, Uppsala, Sweden
- 2015
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Ingår i: Epigenetics. - : Informa UK Limited. - 1559-2294 .- 1559-2308. ; 10, s. 1084-1090
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In June 2015, the fourth European Workshop on Plant Chromatin took place in Uppsala, Sweden, bringing together 80 researchers studying various aspects of plant chromatin and epigenetics. The intricate relationships between plant chromatin dynamics and gene expression change, chromatin organization within the plant cell nucleus, and the impact of chromatin structure on plant development were discussed. Among the main highlights of the meeting were an ever-growing list of newly identified players in chromatin structure establishment and the development of novel tools and approaches to foster our understanding of chromatin-mediated gene regulation, taking into account the context of the plant cell nucleus and its architecture. In this report, we summarize some of the main advances and prospects of plant chromatin research presented at this meeting.
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| 9. |
- Mozgova, Iva, et al.
(författare)
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The Polycomb Group Protein Regulatory Network
- 2015
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Ingår i: Annual Review of Plant Biology. - : Annual Reviews. - 1543-5008 .- 1545-2123. ; 66, s. 269-296
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Forskningsöversikt (refereegranskat)abstract
- Correct expression of specific sets of genes in time and space ensures the establishment and maintenance of cell identity, which is required for proper development of multicellular organisms. Polycomb and Trithorax group proteins form multisubunit complexes that antagonistically act in epigenetic gene repression and activation, respectively. The traditional view of Polycomb repressive complexes (PRCs) as executors of long-lasting and stable gene repression is being extended by evidence of flexible repression in response to developmental and environmental cues, increasing the complexity of mechanisms that ensure selective and properly timed PRC targeting and release of Polycomb repression. Here, we review advances in understanding of the composition, mechanisms of targeting, and function of plant PRCs and discuss the parallels and differences between plant and animal models.
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| 10. |
- Mozgova, Iva, et al.
(författare)
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Transgenerational phenotype aggravation in CAF-1 mutants reveals parent-of-origin specific epigenetic inheritance
- 2018
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 220, s. 908-921
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Tidskriftsartikel (refereegranskat)abstract
- Chromatin is assembled by histone chaperones such as chromatin assembly factor CAF-1. We had noticed that vigor of Arabidopsis thaliana CAF-1 mutants decreased over several generations. Because changes in mutant phenotype severity over generations are unusual, we asked how repeated selfing of Arabidopsis CAF-1 mutants affects phenotype severity.CAF-1 mutant plants of various generations were grown, and developmental phenotypes, transcriptomes and DNA cytosine-methylation profiles were compared quantitatively.Shoot- and root-related growth phenotypes were progressively more affected in successive generations of CAF-1 mutants. Early and late generations of the fasciata (fas)2-4 CAF-1 mutant displayed only limited changes in gene expression, of which increasing upregulation of plant defense-related genes reflects the transgenerational phenotype aggravation. Likewise, global DNA methylation in the sequence context CHG but not CG or CHH (where H = A, T or C) changed over generations in fas2-4. Crossing early and late generation fas2-4 plants established that the maternal contribution to the phenotype severity exceeds the paternal contribution.Together, epigenetic rather than genetic mechanisms underlie the progressive developmental phenotype aggravation in the Arabidopsis CAF-1 mutants and preferred maternal transmission reveals a more efficient reprogramming of epigenetic information in the male than the female germline.
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