Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Apparent loss of PRC2 chromatin occupancy as an artefact of RNA depletion

ABSTRACT: RNA has been implicated in the recruitment of chromatin modifiers, and previous studies have provided evidence in favour and against this idea. RNase treatment of chromatin is a prevalent tool for the study of RNA-mediated regulation of chromatin modifiers, but the limitations of this approach remain unclear. One of the most studied chromatin modifiers in the context of RNA-mediated regulation is the H3K27me3 methyltransferase Polycomb Repressive Complex 2 (PRC2). RNase A treatment during chromatin immunoprecipitation (rChIP) reduces the occupancy of PRC2 on chromatin. This led to suggestions of an “RNA bridge" between PRC2 and chromatin. Here we show that RNase A treatment during chromatin immunoprecipitation leads to the apparent loss of all facultative heterochromatin, including both PRC2 and its H3K27me3 mark genome-wide. This phenomenon persists in mouse embryonic stem cells, human cancer cells and human-induced pluripotent stem cells. We track this observation to a global gain of chromatin that artificially reduces ChIP signals from facultative heterochromatin. Our results point to substantial limitations in RNase A treatment for mapping RNA-dependent chromatin occupancy and invalidate conclusions that were previously established for PRC2 based on this assay.

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE240079 | GEO | 2024/02/21

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

Apparent RNA bridging between PRC2 and chromatin is an artifact of non-specific chromatin precipitation upon RNA degradation

Project description:Polycomb repressive complex 2 (PRC2) modifies chromatin to maintain repression of genes specific for other cell lineages and is essential for development. In vitro, RNA inhibits PRC2 catalytic activity and interaction with nucleosomes but the effect of RNA on PRC2 in cells has been unclear, with studies concluding that RNA either antagonises or promotes the association of PRC2 with chromatin. Suggesting the existence of an RNA bridge that connects PRC2 to chromatin, treatment of formaldehyde-crosslinked, sonicated nuclear extracts with RNase A reduces co-precipitation of polycomb target sites with PRC2. Here, we show that this apparent loss of PRC2 chromatin association after RNase A treatment is due to non-specific chromatin precipitation. RNA degradation causes chromatin to precipitate out of solution, thereby reducing the enrichment of specific DNA sequences in chromatin immunoprecipitation reactions. Maintaining chromatin solubility by the addition of poly-L-glutamic acid (PGA) rescues detection of PRC2 chromatin association upon RNA degradation. These findings undermine support for the model that RNA bridges PRC2 and chromatin in cells.

2024-02-22 | GSE240380 | GEO

Chromatin-associated RNA degradation contributes to silencing of Polycomb target genes

Project description:Polycomb Repressive Complexes 1 and 2 (PRC1 and PRC2) are histone-modifying and -binding complexes that mediate the formation of facultative heterochromatin and are required for silencing of developmental genes and maintenance of cell fate. Multiple pathways of RNA decay work together to establish and maintain heterochromatin in fission yeast, including a recently identified role for a conserved RNA degradation complex called the rixosome or RIX1 complex. Whether RNA degradation also plays a role in the stability of mammalian heterochromatin remains unknown. Here we show that the rixosome contributes to silencing of many Polycomb targets in human cells. The rixosome associates with human PRC complexes and is enriched at promoters of Polycomb target genes. Importantly, depletion of either the rixosome or Polycomb results in accumulation of paused and elongating RNA polymerase at Polycomb-target genes. We identify point mutations in the RING1B subunit of PRC1 that disrupt the interaction between PRC1 and the rixosome and result in diminished silencing, suggesting that direct recruitment of the rixosome to chromatin is required for silencing. Finally, we show that the RNA kinase activity of the rixosome and the XRN2 exoribonuclease, which degrades RNAs with 5’ mono-phosphate groups generated by the rixosome, are required for silencing. Our findings suggest that rixosome-mediated degradation of nascent RNA is conserved from fission yeast to human, although in human cells the rixosome degrades RNA in facultative rather than constitutive heterochromatin.

2022-01-19 | PXD027966 | Pride

Chromatin-associated RNA degradation contributes to silencing of Polycomb target genes

2022-01-20 | PXD029403 | Pride

IMITATION SWITCH is required for normal chromatin structure and gene repression in PRC2 target domains

Project description:Polycomb Group (PcG) proteins are part of an epigenetic cell memory system that plays essential roles in multicellular development, stem cell biology, X-chromosome inactivation, and cancer. In animals, plants, and many fungi, Polycomb Repressive Complex 2 (PRC2) catalyzes trimethylation of histone H3 lysine 27 (H3K27me3) to assemble transcriptionally repressed facultative heterochromatin. PRC2 is structurally and functionally conserved in the model fungus Neurospora crassa, and recent work in this organism has generated insights into PRC2 control and function. To identify new components of the facultative heterochromatin pathway, we performed a targeted screen of Neurospora deletion strains lacking individual ATP-dependent chromatin remodeling enzymes. We found the Neurospora homolog of IMITATION SWITCH (ISW) is critical for normal transcriptional repression, nucleosome organization, and establishment of typical histone methylation patterns in facultative heterochromatin domains. We also found that stable interaction between PRC2 and chromatin depends on ISW. A functional ISW ATPase domain is required for gene repression and H3K27 methylation. ISW homologs interact with accessory proteins to form multiple complexes with distinct functions. Using proteomics and molecular approaches, we identified three distinct Neurospora ISW-containing complexes. A triple mutant lacking three ISW-accessory factors and disrupting multiple ISW complexes led to widespread upregulation of PRC2 target genes and altered H3K27 methylation patterns, similar to an ISW-deficient strain. Taken together, our data show that ISW is a key component of the facultative heterochromatin pathway in Neurospora and that distinct ISW complexes perform an apparently overlapping role to regulate chromatin structure and gene repression at PRC2 target domains.

2021-01-05 | GSE150758 | GEO

RNA is essential for PRC2 chromatin occupancy and function in human pluripotent stem cells

Project description:Many chromatin-binding proteins and protein complexes that regulate transcription also bind RNA. One of these, Polycomb repressive complex 2 (PRC2), deposits the H3K27me3 mark of facultative heterochromatin and is required for stem cell differentiation. PRC2 binds RNAs broadly in vivo and in vitro. Yet, whether this RNA binding has any biological importance remains unsettled. Here we tackle this question in human induced pluripotent stem cells using multiple complementary approaches. Perturbation of RNA-PRC2 interaction by RNaseA, by a chemical inhibitor of transcription, or by an RNA-binding-defective mutant all disrupted PRC2 chromatin occupancy and localization genome-wide. The physiological relevance of PRC2-RNA interactions is further underscored by the dramatic cardiomyocyte differentiation defect upon genetic disruption. We conclude that PRC2 requires RNA binding for chromatin localization in human pluripotent stem cells and in turn for defining cellular state.

2020-05-31 | GSE128135 | GEO

Mapping RNA interactions of human ATRX with RepA fragment of Xist

Project description:Heterochromatin in the eukaryotic genome is rigorously controlled by the concerted action of protein factors and RNAs. Here, we investigate the RNA binding function of ATRX, a chromatin remodeler with roles in silencing of repetitive regions of the genome and in recruitment of the polycomb repressive complex 2 (PRC2). We identify ATRX RNA binding regions (RBRs) and discover that the major ATRX RBR lies within the N-terminal region of the protein, distinct from its PHD and helicase domains. Deletion of this ATRX RBR (ATRXRBR) compromises ATRX interactions with RNAs in vitro and in vivo and alters its chromatin binding properties. Genome-wide studies reveal that loss of RNA interactions results in a redistribution of ATRX on chromatin. Finally, our studies identify a role for ATRX-RNA interactions in regulating PRC2 localization to a subset of polycomb target genes.

2020-03-09 | PXD017806 | Pride

XPC and Non-XPC Cutaneous Squamous Cell Carcinoma Mutation Rate Study

Project description:<p>Base mutations occur at higher frequencies within heterochromatin and late-replicating DNA. In this study, we show that regional differences in mutation frequency are absent in portions of the genome that are not transcribed within cutaneous squamous cell carcinomas (cSCCs) with an XPC-\- genetic background. The XPC-\- genetic background predicates a loss of global genome nucleotide excision repair (GG-NER), thus our data shows that regional differences in mutation frequency are a result of differential access of DNA repair protein. Unexpectedly, we also note that greater transcription reduces mutations on both strands of genes in heterochromatin, and only to those levels observed in euchromatin, in a XPC-dependent fashion. Therefore, transcription likely reduces mutation prevalence by increasing access to DNA repair proteins. This tripartite relationship between DNA repair, transcription, and chromatin state shows a new cancer risk factor in human populations.</p>

| phs000830 | dbGaP

Taz1-Shelterin promotes facultative heterochromatin assembly at chromosome-internal sites containing late replication origins [Taz1]

Project description:Occupancy profiling of Shelterin components in fission yeast. Facultative heterochromatin regulates gene expression, but its assembly is poorly understood. Previously, we identified facultative heterochromatin islands in the fission yeast genome and found that RNA elimination machinery promotes island assembly at meiotic genes. Here, we report that Taz1, a component of the telomere protection complex Shelterin, is required to assemble heterochromatin islands at regions corresponding to late replication origins that are sites of double-strand break formation during meiosis. The loss of Taz1 and other Shelterin subunits, including Ccq1 that interacts with Clr4/Suv39h, abolishes heterochromatin at late origins and causes defective silencing of associated genes. Moreover, the late origin regulator Rif1 affects heterochromatin at Taz1-dependent islands and subtelomeric regions. We uncover a connection between heterochromatin and replication control, and show that heterochromatin factors affect timing of replication. These analyses implicate Shelterin in facultative heterochromatin assembly at late origins, which has important implications for the maintenance of genome stability and gene regulation. Whole cell extract DNA and DNA recovered from Taz1 or Rif1-immunoprecipitated chromatin of fission yeast were random-prime PCR amplified and labeled with Cy3 (whole cell extract DNA) or with Cy5 (IP DNA) and analyzed using custom 60mer Agilent array that tiles Schizosaccharomyces pombe genome in 300bp intervals alternately on both strands.

2016-06-09 | E-GEOD-78822 | biostudies-arrayexpress

Taz1-Shelterin promotes facultative heterochromatin assembly at chromosome-internal sites containing late replication origins [H3K9me2]

Project description:ChIP-chip analyses of lysine 9 dimethylated histone H3 in Shelterin mutants. Facultative heterochromatin regulates gene expression, but its assembly is poorly understood. Previously, we identified facultative heterochromatin islands in the fission yeast genome and found that RNA elimination machinery promotes island assembly at meiotic genes. Here, we report that Taz1, a component of the telomere protection complex Shelterin, is required to assemble heterochromatin islands at regions corresponding to late replication origins that are sites of double-strand break formation during meiosis. The loss of Taz1 and other Shelterin subunits, including Ccq1 that interacts with Clr4/Suv39h, abolishes heterochromatin at late origins and causes defective silencing of associated genes. Moreover, the late origin regulator Rif1 affects heterochromatin at Taz1-dependent islands and subtelomeric regions. We uncover a connection between heterochromatin and replication control, and show that heterochromatin factors affect timing of replication. These analyses implicate Shelterin in facultative heterochromatin assembly at late origins, which has important implications for the maintenance of genome stability and gene regulation. Whole cell extract DNA and DNA recovered from H3K9 dimethylated chromatin of fission yeast were random-prime PCR amplified and labeled with Cy3 (whole cell extract) or Cy5 (IP DNA) and analyzed using custom 60mer Agilent array that tiles Schizosaccharomyces pombe genome in 300bp intervals alternately on both strands.

2016-06-09 | E-GEOD-78820 | biostudies-arrayexpress

Neurospora crassa genome organization requires subtelomeric facultative heterochromatin

Project description:Facultative heterochromatin in the filamentous fungus Neurospora crassa is identified by the repressive histone mark H3K27me3 and is primarily subtelomeric, while constitutive heterochromatin, marked by the DIM-5-catalzyed H3K9me3, is found at centromeres, telomeres, and smaller dispersed regions. In strains lacking constitutive heterochromatin (e.g., Δdim-5), H3K27me2/3 relocalizes to the regions formerly marked by H3K9me3. H3K27me3 is catalyzed by the SET-7 histone methyltransferase subunit of the Polycomb Repressive Complex 2 (PRC2); another PRC2 member, Neurospora p55 (NPF) regulates subtelomeric H3K27me2/3. Despite the de-repression of >70 genes, a Δset-7 strain has no distinguishable phenotype. To investigate the facultative heterochromatin contribution to genome organization, we performed high-throughput “chromosome conformation capture” (Hi-C) on mutants with impacted H3K27me2/3 deposition. A Δset-7 strain has decreased inter-/intra-subtelomeric contacts among others; this pattern is mirrored in a Δnpf strain, which lacks subtelomeric H3K27me3. In a Δset-7 strain, telomere bundles were often uncoupled from the nuclear membrane and de-repressed genes were subtelomeric. The chromosome conformation of a Δset-7;Δdim-5 double mutant was similar to Δset-7, suggesting that facultative heterochromatin relocalization does not compensate for H3K9me3 loss and rescue the Neurospora genome organization in strains with defective constitutive heterochromatin.

2016-10-27 | GSE82222 | GEO

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data