scholarly journals High-resolution and High-accuracy Topographic and Transcriptional Maps of the Nucleosome Barrier

2019 ◽  
Author(s):  
Zhijie Chen ◽  
Ronen Gabizon ◽  
Aidan I. Brown ◽  
Antony Lee ◽  
Aixin Song ◽  
...  
Keyword(s):  
High Resolution ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
High Accuracy ◽  
List Type ◽  
Control Of Gene Expression ◽  
Pol Ii ◽  
Time Dynamics ◽  
Crossing Time ◽  
Transcriptional Landscape

AbstractNucleosomes represent mechanical and energetic barriers that RNA Polymerase II (Pol II) must overcome during transcription. A high-resolution description of the barrier topography, its modulation by epigenetic modifications, and their effects on Pol II nucleosome crossing dynamics, is still missing. Here, we obtain topographic and transcriptional (Pol II residence time) maps of canonical, H2A.Z, and monoubiquitinated H2B (uH2B) nucleosomes at near base-pair resolution and accuracy. Pol II crossing dynamics are complex, displaying pauses at specific loci, backtracking, and nucleosome hopping between wrapped states. While H2A.Z widens the barrier, uH2B heightens it, and both modifications greatly lengthen Pol II crossing time. Using the dwell times of Pol II at each nucleosomal position we extract the energetics of the barrier. The orthogonal barrier modifications of H2A.Z and uH2B, and their effects on Pol II dynamics rationalize their observed enrichment in +1 nucleosomes and suggest a mechanism for selective control of gene expression.HighlightsA single-molecule unzipping assay mimics DNA unwinding by Pol II and maps the topography of human canonical, H2A.Z and uH2B nucleosome barriers at high resolutionReal-time dynamics and full molecular trajectories of Pol II crossing the nucleosomal barrier reveal the transcriptional landscape of the barrier at high accuracyH2A.Z enhances the width and uH2B the height of the barrierA unified mechanical model links position-dependent dwell times of Pol II on the nucleosome with energetics of the barrier

scholarly journals High-resolution and high-accuracy topographic and transcriptional maps of the nucleosome barrier

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Zhijie Chen ◽  
Ronen Gabizon ◽  
Aidan I Brown ◽  
Antony Lee ◽  
Aixin Song ◽  
...  
Keyword(s):  
Gene Expression ◽  
High Resolution ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Residence Time ◽  
Base Pair ◽  
High Accuracy ◽  
Control Of Gene Expression ◽  
Pol Ii ◽  
Crossing Time

Nucleosomes represent mechanical and energetic barriers that RNA Polymerase II (Pol II) must overcome during transcription. A high-resolution description of the barrier topography, its modulation by epigenetic modifications, and their effects on Pol II nucleosome crossing dynamics, is still missing. Here, we obtain topographic and transcriptional (Pol II residence time) maps of canonical, H2A.Z, and monoubiquitinated H2B (uH2B) nucleosomes at near base-pair resolution and accuracy. Pol II crossing dynamics are complex, displaying pauses at specific loci, backtracking, and nucleosome hopping between wrapped states. While H2A.Z widens the barrier, uH2B heightens it, and both modifications greatly lengthen Pol II crossing time. Using the dwell times of Pol II at each nucleosomal position we extract the energetics of the barrier. The orthogonal barrier modifications of H2A.Z and uH2B, and their effects on Pol II dynamics rationalize their observed enrichment in +1 nucleosomes and suggest a mechanism for selective control of gene expression.

Real-Time Dynamics of RNA Polymerase II Clustering in Live Human Cells

Science ◽  
2013 ◽  
Vol 341 (6146) ◽  
pp. 664-667 ◽  
Author(s):  
Ibrahim I. Cisse ◽  
Ignacio Izeddin ◽  
Sebastien Z. Causse ◽  
Lydia Boudarene ◽  
Adrien Senecal ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Eukaryotic Cells ◽  
Average Lifetime ◽  
Pol Ii ◽  
Time Dynamics ◽  
External Signals ◽  
Rate Limiting

Transcription is reported to be spatially compartmentalized in nuclear transcription factories with clusters of RNA polymerase II (Pol II). However, little is known about when these foci assemble or their relative stability. We developed a quantitative single-cell approach to characterize protein spatiotemporal organization, with single-molecule sensitivity in live eukaryotic cells. We observed that Pol II clusters form transiently, with an average lifetime of 5.1 (± 0.4) seconds, which refutes the notion that they are statically assembled substructures. Stimuli affecting transcription yielded orders-of-magnitude changes in the dynamics of Pol II clusters, which implies that clustering is regulated and plays a role in the cell’s ability to effect rapid response to external signals. Our results suggest that transient crowding of enzymes may aid in rate-limiting steps of gene regulation.

scholarly journals Live-cell single particle imaging reveals the role of RNA polymerase II in histone H2A.Z eviction

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Anand Ranjan ◽  
Vu Q Nguyen ◽  
Sheng Liu ◽  
Jan Wisniewski ◽  
Jee Min Kim ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Transcription Initiation ◽  
General Mechanism ◽  
Pol Ii ◽  
Promoter Escape ◽  
Genome Wide ◽  
A Genome ◽  
Particle Imaging

The H2A.Z histone variant, a genome-wide hallmark of permissive chromatin, is enriched near transcription start sites in all eukaryotes. H2A.Z is deposited by the SWR1 chromatin remodeler and evicted by unclear mechanisms. We tracked H2A.Z in living yeast at single-molecule resolution, and found that H2A.Z eviction is dependent on RNA Polymerase II (Pol II) and the Kin28/Cdk7 kinase, which phosphorylates Serine 5 of heptapeptide repeats on the carboxy-terminal domain of the largest Pol II subunit Rpb1. These findings link H2A.Z eviction to transcription initiation, promoter escape and early elongation activities of Pol II. Because passage of Pol II through +1 nucleosomes genome-wide would obligate H2A.Z turnover, we propose that global transcription at yeast promoters is responsible for eviction of H2A.Z. Such usage of yeast Pol II suggests a general mechanism coupling eukaryotic transcription to erasure of the H2A.Z epigenetic signal.

scholarly journals Stress-Induced Transcriptional Memory Accelerates Promoter-Proximal Pause-Release and Decelerates Termination over Mitotic Divisions

2019 ◽  
Author(s):  
Anniina Vihervaara ◽  
Dig Bijay Mahat ◽  
Samu V. Himanen ◽  
Malin A.H. Blom ◽  
John T. Lis ◽  
...  
Keyword(s):  
Heat Shock ◽  
Rna Polymerase Ii ◽  
Transcriptional Response ◽  
Regulatory Elements ◽  
List Type ◽  
Pol Ii ◽  
Daughter Cells ◽  
Heat Shocks ◽  
Transcriptional Memory ◽  
Pol Ii Pausing

SummaryHeat shock triggers an instant reprogramming of gene and enhancer transcription, but whether cells encode a memory to stress, at the level of nascent transcription, has remained unknown. Here, we measured transcriptional response to acute heat stress in unconditioned cells and in daughters of cells that had been exposed to a single or multiple heat shocks. Tracking RNA Polymerase II (Pol II) genome-wide at nucleotide-resolution revealed that cells precisely remember their transcriptional identity throughout stress, restoring Pol II distribution at gene bodies and enhancers upon recovery. However, single heat shock primed faster gene-induction in the daughter cells by increasing promoter-proximal Pol II pausing, and accelerating the pause-release. In repeatedly stressed cells, both basal and inducible transcription was refined, and pre-mRNA processing decelerated, which retained transcripts on chromatin and reduced recycling of the transcription machinery. These results mechanistically uncovered how the steps of pause-release and termination maintain transcriptional memory over mitosis.Highlights-Cell type-specific transcription precisely recovers after heat-induced reprogramming-Single heat shock primes genes for accelerated induction over mitotic divisionsviaincreased promoter-proximal Pol II pausing and faster pause-release-Multiple heat shocks refine basal and inducible transcription over mitotic divisions to support survival of the daughter cells-Decelerated termination at active genes reduces recycling of Pol II to heat-activated promoters and enhancers-HSF1 increases the rate of promoter-proximal pause-releaseviadistal and proximal regulatory elements

scholarly journals Cohesin removal reprograms gene expression upon mitotic entry

2019 ◽  
Author(s):  
Carlos Perea-Resa ◽  
Leah Bury ◽  
Iain Cheeseman ◽  
Michael D. Blower
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Rna Polymerase Ii ◽  
Chromosome Segregation ◽  
List Type ◽  
Mitotic Chromosomes ◽  
Rna Pol Ii ◽  
Pol Ii ◽  
Mitotic Entry ◽  
Nascent Transcripts

SummaryEntering mitosis, the genome is restructured to facilitate chromosome segregation, accompanied by dramatic changes in gene expression. However, the mechanisms that underlie mitotic transcriptional regulation are unclear. In contrast to transcribed genes, centromere regions retain transcriptionally active RNA Polymerase II (RNAPII) in mitosis. Here, we demonstrate that chromatin-bound cohesin is sufficient to retain RNAPII at centromeres while WAPL-mediated removal of cohesin during prophase is required for RNAPII dissociation from chromosome arms. Failure to remove cohesin from chromosome arms results in a failure to release elongating RNAPII and nascent transcripts from mitotic chromosomes and dramatically alters gene expression. We propose that prophase cohesin removal is the key step in reprogramming gene expression as cells transition from G2 to mitosis, and is temporally coupled with chromosome condensation to coordinate chromosome segregation with changes in gene expression.HighlightsMitotic centromere transcription requires cohesinCohesin removal releases elongating RNA Pol II and nascent RNA from chromatinThe prophase pathway reprograms gene expression during mitosis

scholarly journals Integrator terminates promoter-proximal Pol II to generate C. elegans piRNA precursors

2020 ◽  
Author(s):  
Toni Beltran ◽  
Elena Pahita ◽  
Subhanita Ghosh ◽  
Boris Lenhard ◽  
Peter Sarkies
Keyword(s):  
Catalytic Activity ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcription Termination ◽  
List Type ◽  
Germline Development ◽  
Pol Ii ◽  
C Elegans

AbstractPiwi-interacting RNAs (piRNAs) play key roles in germline development and genome defence in metazoans. In C. elegans, piRNAs are transcribed from >15000 discrete genomic loci by RNA polymerase II, resulting in 28 nt short-capped piRNA precursors. Here we investigate transcription termination at piRNA loci. We show that the Integrator complex, which terminates snRNA transcription, is recruited to piRNA loci. We show that the catalytic activity of Integrator cleaves nascent capped piRNA precursors associated with promoter-proximal Pol II, resulting in termination of transcription. Loss of Integrator activity, however, does not result in transcriptional readthrough at the majority of piRNA loci. Our results draw new parallels between snRNA and piRNA biogenesis in nematodes, and provide evidence of a role for the Integrator complex as a terminator of promoter-proximal RNA polymerase II.Highlights- Integrator localises to sites of piRNA biogenesis in nematodes- Integrator cleaves nascent RNAs associated with promoter-proximal Pol II at piRNA loci to release short capped piRNA precursors from chromatin- Repression of Pol II elongation at the majority of piRNA loci is independent of Integrator

Release of human TFIIB from actively transcribing complexes is triggered upon synthesis of 7 nt and 9 nt RNAs

2019 ◽  
Author(s):  
Elina Ly ◽  
Abigail E. Powell ◽  
James A. Goodrich ◽  
Jennifer F. Kugel
Keyword(s):  
Rna Polymerase Ii ◽  
Single Molecule ◽  
Trigger Points ◽  
Pol Ii ◽  
Transcription System ◽  
Recognition Element ◽  
General Transcription Factors ◽  
Early Transcription ◽  
Promoter Dna

AbstractRNA polymerase II (Pol II) and its general transcription factors assemble on the promoters of mRNA genes to form large macromolecular complexes that initiate transcription in a regulated manner. During early transcription these complexes undergo dynamic rearrangement and disassembly as Pol II moves away from the start site of transcription and transitions into elongation. One step in disassembly is the release of the general transcription factor TFIIB, although the mechanism of release and its relationship to the activity of transcribing Pol II is not understood. We developed a single molecule fluorescence transcription system to investigate TFIIB release in vitro. Leveraging our ability to distinguish active from inactive complexes, we found that nearly all transcriptionally active complexes release TFIIB during early transcription. Release is not dependent on the contacts TFIIB makes with its recognition element in promoter DNA. We identified two different points in early transcription at which release is triggered, reflecting heterogeneity across the population of actively transcribing complexes. TFIIB releases after both trigger points with similar kinetics, suggesting the rate of release is independent of the molecular transformations that prompt release. Together our data support the model that TFIIB release is important to maintain the transcriptional activity of Pol II as initiating complexes transition into elongation complexes.

scholarly journals The Integrator complex terminates promoter-proximal transcription at protein-coding genes

2019 ◽  
Author(s):  
Nathan D. Elrod ◽  
Telmo Henriques ◽  
Kai-Lieh Huang ◽  
Deirdre C. Tatomer ◽  
Jeremy E. Wilusz ◽  
...  
Keyword(s):  
Rna Polymerase Ii ◽  
List Type ◽  
Protein Coding ◽  
Pol Ii ◽  
Bacterial Transcription ◽  
Number Of Genes ◽  
Nascent Rna ◽  
Template Dna ◽  
Productive Elongation ◽  
Rna Endonuclease

SUMMARYThe transition of RNA polymerase II (Pol II) from initiation to productive elongation is a central, regulated step in metazoan gene expression. At many genes, Pol II pauses stably in early elongation, remaining engaged with the 25-60 nucleotide-long nascent RNA for many minutes while awaiting signals for release into the gene body. However, a number of genes display highly unstable promoter Pol II, suggesting that paused polymerase might dissociate from template DNA at these promoters and release a short, non-productive mRNA. Here, we report that paused Pol II can be actively destabilized by the Integrator complex. Specifically, Integrator utilizes its RNA endonuclease activity to cleave nascent RNA and drive termination of paused Pol II. These findings uncover a previously unappreciated mechanism of metazoan gene repression, akin to bacterial transcription attenuation, wherein promoter-proximal Pol II is prevented from entering productive elongation through factor-regulated termination.HighlightsThe Integrator complex inhibits transcription elongation at ∼15% of mRNA genesIntegrator targets promoter-proximally paused Pol II for terminationThe RNA endonuclease of Integrator subunit 11 is critical for gene attenuationIntegrator-repressed genes are enriched in signaling and growth-responsive pathways

scholarly journals Hyperosmotic stress induces downstream-of-gene transcription and alters the RNA Polymerase II interactome despite widespread transcriptional repression

2020 ◽  
Author(s):  
Nicolle A. Rosa-Mercado ◽  
Joshua T. Zimmer ◽  
Maria Apostolidi ◽  
Jesse Rinehart ◽  
Matthew D. Simon ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Transcriptional Response ◽  
Hyperosmotic Stress ◽  
Transcriptional Level ◽  
List Type ◽  
Upstream Gene ◽  
Pol Ii ◽  
Transcription Profiles

SummaryStress-induced readthrough transcription results in the synthesis of thousands of downstream-of-gene (DoG) containing transcripts. The mechanisms underlying DoG formation during cellular stress remain unknown. Nascent transcription profiles during DoG induction in human cell lines using TT-TimeLapse-seq revealed that hyperosmotic stress induces widespread transcriptional repression. Yet, DoGs are produced regardless of the transcriptional level of their upstream genes. ChIP-seq confirmed that the stress-induced redistribution of RNA Polymerase (Pol) II correlates with the transcriptional output of genes. Stress-induced alterations in the Pol II interactome are observed by mass spectrometry. While subunits of the cleavage and polyadenylation machinery remained Pol II-associated, Integrator complex subunits dissociated from Pol II under stress conditions. Depleting the catalytic subunit of the Integrator complex, Int11, using siRNAs induces hundreds of readthrough transcripts, whose parental genes partially overlap those of stress-induced DoGs. Our results provide insights into the mechanisms underlying DoG production and how Integrator activity influences DoG transcription.In briefRosa-Mercado et al. report that hyperosmotic stress causes widespread transcriptional repression in human cells, yet DoGs arise regardless of the transcriptional response of their upstream genes. They find that the interaction between Pol II and Integrator is disrupted by hypertonicity and that knocking down the Integrator nuclease leads to DoG production.HighlightsHyperosmotic stress triggers transcriptional repression of many genes.DoG RNAs arise independent of the transcriptional level of their upstream gene.The interaction between Pol II and Integrator subunits decreases after salt stress.Depletion of the Int11 nuclease subunit induces the production of hundreds of DoGs.

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