Biology subjects

Mozgova, I.

Publications and source records attributed to Mozgova, I..

5 recordsLinked to original sources

bioRxiv2026

PWO1 and TRB proteins coordinate chromatin regulation to prevent premature differentiation and ectopic lignin deposition in Arabidopsis

The Arabidopsis PWWP-DOMAIN INTERACTOR OF POLYCOMBS1 (PWO1) and Telomere Repeat-Binding Proteins 1-3 (TRB1-3, TRBs) associate with distinct and shared protein complexes involved in epigenetic regulation, yet their cooperative roles in chromatin control and plant development remain largely unexplored. Here, we show that the interaction between PWO1 and TRBs is evolutionarily conserved. Both PWO1 and TRBs associate with plant telomeres, interact at these regions, and are co-enriched at subsets of interspersed telo-box motifs across regulatory regions genome-wide. TRBs facilitate PWO1 binding at shared genomic regions, including telo-box motifs. PWO1 and TRBs share a substantial number of genomic targets and preferentially bind chromatin regions associated with transcriptionally active states, whereas TRBs alone associate with repressive marks at thousands of loci. Genetic analyses show that the pwo1 trb1 trb3 triple mutant displays severe developmental defects, including main stem arrest and early maturation associated with aberrant lignin deposition in interfascicular tissues. In the triple mutant, key enzymes in the lignin biosynthesis pathway are upregulated, indicating that PWO1, TRB1, and TRB3 cooperatively regulate secondary cell wall formation. Together, our findings provide new insights into how PWO1 and TRBs cooperate to regulate chromatin states and orchestrate plant development, highlighting their central role in controlling gene expression programs. Significance statementThis study shows that PWO1 and TRB proteins co-occupy telomeres, including interspersed telo-box motifs, to regulate chromatin organization and plant development, particularly ectopic lignin deposition. Our findings reveal how these nuclear protein factors coordinate epigenetic states in Arabidopsis thaliana, providing a framework for understanding the control of developmental programs. O_FIG O_LINKSMALLFIG WIDTH=198 HEIGHT=200 SRC="FIGDIR/small/740627v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1a3d544org.highwire.dtl.DTLVardef@1067082org.highwire.dtl.DTLVardef@1c49163org.highwire.dtl.DTLVardef@252171_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstract:C_FLOATNO Evolutionarily conserved PWO-TRB interactions and their shared roles in chromatin regulation and plant development. Created with BioRender.com. C_FIG

plant biology↗

bioRxiv2026

GCN5 negatively regulates class III peroxidases PRX71 and PRX33 to promote lignin deposition in Arabidopsis

Histone acetylation shapes transcriptional programs during environmental stress. The Arabidopsis histone acetyltransferase GCN5/HAG1, a catalytic subunit of the SAGA complex, has been implicated in salt stress responses and cell wall integrity. Here, we show that loss of GCN5 enhances reactive oxygen species (ROS) accumulation under NaCl stress and is accompanied by altered expression of class III peroxidase genes, with strong salt-induced upregulation of PRX71 and elevated basal PRX33 transcript abundance. Consistent with a role for these peroxidases in stress-associated cell wall remodeling, overexpression of PRX71 or PRX33 in the wild-type is sufficient to promote ectopic lignin deposition in roots. Conversely, prx71 and prx33 mutants show improved growth under salt stress and on the cellulose biosynthesis inhibitor isoxaben, and they lack the pronounced ectopic root lignification observed in gcn5 under salt stress. Chromatin immunoprecipitation followed by qPCR (ChIP-qPCR) reveals reduced H3K9 acetylation at PRX71 and PRX33 promoter regions in gcn5 compared with the wild-type, and reduced transcript abundance of candidate upstream transcription factors (TFs), including GATA21 and MYBS2, accompanied by reduced H3K9ac at their loci. Together, our results support a model in which GCN5 constrains PRX71/PRX33-mediated lignification during stress, likely through an indirect regulatory route that integrates chromatin state and transcription factor activity to limit stress-associated lignification while maintaining root growth under salt stress.

plant biology↗

bioRxiv2025

PWO proteins are associated with PRC2 since their emergence in vascular plants

PWWP-Domain Interactor of Polycombs 1 (PWO1), also known as PWWP1, interacts with the catalytic subunits of the Polycomb Repressive Complex 2 (PRC2) and, together with PWO2/3 proteins, plays a critical role in the development of Arabidopsis thaliana (At). PWOs are unique to plants and impact chromatin structure by enabling crosstalk between active and repressive epigenetic marks through mechanisms that are not yet fully understood. We aimed to understand the evolution of PWO proteins and whether their interaction with PRC2 has been conserved through evolution. Our study reveals that PWO proteins are present in vascular plants, but absent in bryophytes and green algae. The ancestral clade of PWO proteins includes the Selaginella moellendorffii (Sm) PWO orthologs SmPWOa and SmPWOb. Transient expression assays showed that both AtPWO1 and SmPWOa form nuclear speckles where they tether At, Sm, but also Physcomitrium patens (Pp) PRC2 catalytic subunits, despite the absence of PWO proteins in Pp. The PWO-PRC2 interactions were confirmed by protein-protein analyses. A newly identified evolutionarily conserved short C-terminal alpha-helix (c-motif) in PWO proteins contributes to an interaction interface for PWO-PRC2 binding. SmPWOs partially rescue the pwo1;pwo2 mutant phenotype in Arabidopsis, highlighting the functional conservation of PWOs in vascular plants.

plant biology↗

bioRxiv2024

PRC2 facilitates the transition from heterotrophy to photoautotrophy during seedling emergence

Seed-to-seedling transition represents a key developmental and metabolic switch in plants. Catabolism of seed storage reserves fuels germination and early seedling emergence until photosynthesis is established. The developmental transition is controlled by Polycomb repressive complex 2 (PRC2). However, the coordination of PRC2 activity and its contribution to transcriptional reprogramming during seedling establishment is unknown. By analysing the re-distribution of H3K27me3 and changes in gene transcription in shoot and root tissues of heterotrophic and photoautotrophic seedlings, we reveal two phases of PRC2-mediated gene repression. The first phase is independent of light and photosynthesis and results in irreversible repression of the embryo maturation programme, marked by heterotrophy and biosynthesis of reserve storage molecules. The second phase is associated with the repression of metabolic pathways related to germination and early seedling emergence, and H3K27me3 deposition in this phase is sensitive to photosynthesis inhibition. We show that preventing transcription of the PRC2-repressed glyoxylate cycle gene ISOCITRATE LYASE is sufficient to drive the vegetative phase transition in PRC2-depleted plants. This underscores a key role of PRC2 repression in the coordinated metabolic and developmental switches during seedling emergence and emphasizes the close connection between metabolic and developmental identities.

plant biology↗

bioRxiv2024

The expansion and diversification of epigenetic regulatory networks underpins major transitions in the evolution of land plants

Epigenetic silencing is essential for regulating gene expression and cellular diversity in eukaryotes. While DNA and H3K9 methylation silence transposable elements (TEs), H3K27me3 marks deposited by the Polycomb repressive complex 2 (PRC2) silence varying proportions of TEs and genes across different lineages. Despite the major development role epigenetic silencing plays in multicellular eukaryotes, little is known about how epigenetic regulatory networks were shaped over evolutionary time. Here, we analyse epigenomes from diverse species across the green lineage to infer the chronological epigenetic recruitment of genes during land plant evolution. We first reveal the nature of plant heterochromatin in the unicellular chlorophyte microalga Chlorella sorokiniana and identify several genes marked with H3K27me3, highlighting the deep origin of PRC2-regulated genes in the green lineage. By incorporating genomic phylostratigraphy, we show how genes of differing evolutionary age occupy distinct epigenetic states in plants. While young genes tend to be silenced by H3K9 methylation, genes that emerged in land plants are preferentially marked with H3K27me3, some of which form part of a common network of PRC2-repressed genes across distantly-related species. Finally, we analyse the potential recruitment of PRC2 to plant H3K27me3 domains and identify conserved DNA-binding sites of ancient transcription factor (TF) families known to interact with PRC2. Our findings shed light on the conservation and potential origin of epigenetic regulatory networks in the green lineage, while also providing insight into the evolutionary dynamics and molecular triggers that underlie the adaptation and elaboration of epigenetic regulation, laying the groundwork for its future consideration in other eukaryotic lineages.

evolutionary biology↗