Mediator and Pol II form diffraction-sized condensates dependent on active transcription in living stem cells
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ABSTRACT:
PROVIDER: PRJNA474953 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR7275200.fastq.gz | Fastqsanger.gz | |||
| SRR7275210.fastq.gz | Fastqsanger.gz | |||
| SRR7275201.fastq.gz | Fastqsanger.gz | |||
| SRR7275202.fastq.gz | Fastqsanger.gz | |||
| SRR7275203.fastq.gz | Fastqsanger.gz |
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Project description:Gene activation is thought to involve a multistep process whereby transcription factors bind to distal enhancer sites and recruit the Mediator complex which contacts the pre-initiating RNA Polymerase II (Pol II) complex assembled at the start site of the gene. The interaction of Mediator and Pol II has yet to be observed in the nucleus of living cells and the dynamics of this interaction are not yet elucidated. Here we use quantitative live cell super-resolution and light sheet imaging to study the organization and dynamics of endogenous Mediator and Pol II directly in living mouse embryonic stem cells. In addition to forming transient clusters with average lifetimes of 11.1 (± 0.9) s, and 12.1 (± 1.4) s respectively, Mediator and Pol II also form large and stable clusters in stem cells (~15 stable clusters per cell). The large and stable Mediator and Pol II clusters gradually disappear within hours after induction of stem cell differentiation. Mediator and Pol II colocalize in the large clusters. Inhibition of Brd4 bromodomains necessary for enhancer association eliminates both Mediator and Pol II stable clusters, and inhibition of transcription elongation selectively eliminates stable Pol II but not stable Mediator clusters. Tracking of Mediator and Pol II stable clusters suggests they are chromatin associated and they coalesce upon contact, a property associated with phase separated droplets. We conclude that Mediator and Pol II associate in diffraction-sized condensates with a defined lifetime dependent on active transcription in living stem cells.
2018-07-22 | GSE115436 | GEO
Project description:The synthesis of pre-mRNA by RNA polymerase II (Pol II) involves the formation of a transcription initiation complex, and a transition to an elongation complex. The large subunit of Pol II contains an intrinsically disordered C-terminal domain that is phosphorylated by cyclin-dependent kinases during the transition from initiation to elongation, thus influencing the interaction of the C-terminal domain with different components of the initiation or the RNA-splicing apparatus. Recent observations suggest that this model provides only a partial picture of the effects of phosphorylation of the C-terminal domain. Both the transcription-initiation machinery and the splicing machinery can form phase-separated condensates that contain large numbers of component molecules: hundreds of molecules of Pol II and mediator are concentrated in condensates at super-enhancers, and large numbers of splicing factors are concentrated in nuclear speckles, some of which occur at highly active transcription sites. Here we investigate whether the phosphorylation of the Pol II C-terminal domain regulates the incorporation of Pol II into phase-separated condensates that are associated with transcription initiation and splicing. We find that the hypophosphorylated C-terminal domain of Pol II is incorporated into mediator condensates and that phosphorylation by regulatory cyclin-dependent kinases reduces this incorporation. We also find that the hyperphosphorylated C-terminal domain is preferentially incorporated into condensates that are formed by splicing factors. These results suggest that phosphorylation of the Pol II C-terminal domain drives an exchange from condensates that are involved in transcription initiation to those that are involved in RNA processing, and implicates phosphorylation as a mechanism that regulates condensate preference.
2019-06-17 | GSE120656 | GEO
Project description:lncRNA DIGIT and BRD3 protein form phase-separated condensates to regulate endoderm differentiation
2020-07-08 | GSE149032 | GEO
Project description:The gene expression programs that define each cell’s identity are controlled by master transcription factors (TFs) that bind cell-type specific enhancers, as well as signaling factors, which bring extracellular stimuli to these enhancers. Recent studies have revealed that master TFs form phase-separated condensates with the Mediator coactivator at super-enhancers. Here we present evidence that signaling factors for the WNT, TGF-β and JAK/STAT pathways employ their intrinsically disordered regions (IDRs) to enter and concentrate in Mediator condensates at super-enhancers. We show that the WNT coactivator β-catenin interacts both with components of condensates and DNA binding factors to selectively occupy super-enhancer associated genes. We propose that the cell-type specificity of the response to signaling is mediated, in part, by the IDRs of the signaling factors, which cause these factors to partition into condensates established by the master TFs and Mediator at genes with prominent roles in cell identity.
2020-01-31 | GSE134387 | GEO
Project description:Pol II phosphorylation regulates a switch between transcriptional and splicing condensates
| PRJNA493945 | ENA
Project description:Pol II(G) is a novel form of RNA polymerase II that contains a tightly associated Gdown1 polypeptide. Whereas Pol II suffices for robust activator-dependent transcription in the absence of Mediator, Pol II(G) is highly dependent upon Mediator in a biochemically defined in vitro system. However, the mechanism(s) whereby Gdown1 alters the coactivator-dependence of Pol II is unknown. Here we show that Gdown1 competes with TFIIF for binding to the RPB1 and RPB5 subunits of Pol II in vitro, resulting in inhibition of a critical function of TFIIF in facilitating PIC assembly. The apparent inability of Pol II(G) to associate with TFIIF suggests that Gdown1 must be removed from Pol II for transcription initiation. However, Mediator can actually help Pol II(G) bind to the promoter prior to subsequent Mediator functions. Complementary cell-based analyses reveal that Pol II(G) is recruited to promoter regions of subsets of actively transcribed genes, where Pol II(G) appears to modulate transcription. Our findings indicate that differential regulation of subsets of genes by Pol II and Pol II(G) occurs through the regulation of TFIIF and consequent alterations in Mediator requirements. Genome-wide localization of PolII and Gdown1 in human IMR90 fibroblast cells using ChIP-seq
2012-01-13 | E-GEOD-33128 | biostudies-arrayexpress
Project description:lncRNA DIGIT and BRD3 protein form phase-separated condensates to regulate endoderm differentiation
| PRJNA522865 | ENA
Project description:Biomolecular condensates composed of proteins and RNA are one approach by which cells regulate post-transcriptional gene expression. Their formation typically involves the phase separation of intrinsically disordered proteins with a target mRNA, sequestering the mRNA into a liquid condensate. This sequestration regulates gene expression by modulating translation or facilitating RNA processing. Here, we engineer synthetic condensates using a fusion of an RNA-binding protein, the human Pumilio2 homology domain, and a synthetic intrinsically disordered protein, an elastin-like polypeptide, that can bind and sequester a target mRNA transcript. In protocells, sequestration of a target mRNA largely limits its translation. Conversely, in E. Coli, sequestration of the same target mRNA increases its translation. We characterize the Pum2-ELP condensate system using microscopy, biophysical and biochemical assays, and RNA-seq. This approach enables modulation of cell function via the formation of synthetic biomolecular condensates that upregulate the expression of a target protein.
2024-11-30 | GSE277409 | GEO
Project description:Pol II(G) is a novel form of RNA polymerase II that contains a tightly associated Gdown1 polypeptide. Whereas Pol II suffices for robust activator-dependent transcription in the absence of Mediator, Pol II(G) is highly dependent upon Mediator in a biochemically defined in vitro system. However, the mechanism(s) whereby Gdown1 alters the coactivator-dependence of Pol II is unknown. Here we show that Gdown1 competes with TFIIF for binding to the RPB1 and RPB5 subunits of Pol II in vitro, resulting in inhibition of a critical function of TFIIF in facilitating PIC assembly. The apparent inability of Pol II(G) to associate with TFIIF suggests that Gdown1 must be removed from Pol II for transcription initiation. However, Mediator can actually help Pol II(G) bind to the promoter prior to subsequent Mediator functions. Complementary cell-based analyses reveal that Pol II(G) is recruited to promoter regions of subsets of actively transcribed genes, where Pol II(G) appears to modulate transcription. Our findings indicate that differential regulation of subsets of genes by Pol II and Pol II(G) occurs through the regulation of TFIIF and consequent alterations in Mediator requirements.
2012-01-13 | GSE33128 | GEO
Project description:MeCP2 (methyl CpG binding protein 2) is a key component of constitutive heterochromatin, which plays important roles in chromosome maintenance and transcriptional silencing. Mutations in MeCP2 cause Rett syndrome (RTT), a postnatal progressive neurodevelopmental disorder associated with severe mental disability and autism-like symptoms that manifests in girls during early childhood. Heterochromatin, long considered a dense and relatively static structure, is now understood to exhibit properties consistent with a liquid-like condensate. Here we report that MeCP2 is a dynamic component of heterochromatin condensates in cells, is stimulated by DNA to form liquid-like condensates, contains multiple domains that contribute to condensate formation, manifests physicochemical properties that selectively concentrate heterochromatin cofactors compared to components of transcriptionally active condensates, and when altered by RTT-causing mutations is disrupted in its ability to form condensates. We propose that MeCP2 enhances heterochromatin/euchromatin separation through its condensate partitioning properties and that condensate disruption may be a common consequence of RTT patient mutations.
2020-06-23 | GSE139033 | GEO