Project description:Fluctuations in nutrient availability profoundly impact gene expression. Previous work revealed post-recruitment regulation of RNA Polymerase II (Pol II) during starvation and recovery in Caenorhabitis elegans, suggesting promoter-proximal pausing promotes rapid response to feeding. To test this hypothesis, we measured Pol II elongation genome-wide by two complementary approaches and analyzed elongation in conjunction with Pol II binding and expression. We confirmed bona fide pausing during starvation and also discovered Pol II docking. Pausing occurs at active stress-response genes that become down-regulated in response to feeding. In contrast M-bM-^@M-^\dockedM-bM-^@M-^] Pol II accumulates without initiating upstream of inactive growth genes that become rapidly up-regulated upon feeding. Beyond differences in function and expression, these two sets of genes have different core promoter motifs, suggesting alternative transcriptional machinery. Our work suggests that growth and stress genes are both regulated post-recruitment during starvation, but at initiation and elongation, respectively, coordinating gene expression with nutrient availability. We sequenced short, capped RNA (scRNA-seq) from N2 starved L1 C. elegans as well as a TFIIS mutant (RB2083). We also prepared scRNA-seq libraries from L1 larvae using one, two, or three of the enymes used to prepare the scRNA sequencing libraries as well as scRNA-seq libraries from Drosophila S2 cells using one or two of the enzymes. We further sequenced the 5' end of mRNA in starved C. elegans L1 larvae using the same enzymes as scRNA-seq.
Project description:Fluctuations in nutrient availability profoundly impact gene expression. Previous work revealed post-recruitment regulation of RNA Polymerase II (Pol II) during starvation and recovery in Caenorhabitis elegans, suggesting promoter-proximal pausing promotes rapid response to feeding. To test this hypothesis, we measured Pol II elongation genome-wide by two complementary approaches and analyzed elongation in conjunction with Pol II binding and expression. We confirmed bona fide pausing during starvation and also discovered Pol II docking. Pausing occurs at active stress-response genes that become down-regulated in response to feeding. In contrast “docked” Pol II accumulates without initiating upstream of inactive growth genes that become rapidly up-regulated upon feeding. Beyond differences in function and expression, these two sets of genes have different core promoter motifs, suggesting alternative transcriptional machinery. Our work suggests that growth and stress genes are both regulated post-recruitment during starvation, but at initiation and elongation, respectively, coordinating gene expression with nutrient availability.
Project description:This SuperSeries is composed of the following subset Series: GSE31485: CTCF promotes RNA pol II pausing and links DNA methylation to alternative splicing [ChIP-Seq] GSE31486: CTCF promotes RNA pol II pausing and links DNA methylation to alternative splicing [RNA-Seq] Refer to individual Series
Project description:RNA polymerase II (pol II) transcribes all protein-coding and many non-coding RNAs in the human genome. Pol II transcription initiation is governed by the Pre-Initiation Complex (PIC), which contains TFIIA, TFIIB, TFIID, TFIIE, TFIIF, TFIIH, pol II, and Mediator. After initiation, pol II enzymes typically pause after transcribing less than 100 bases, and paused polymerases represent a common regulatory intermediate. Accordingly, paused pol II has been implicated in enhancer function, development and homeostasis, and diseases ranging from cancer to viral pathogenesis. Precisely how pol II promoter-proximal pausing is enforced and regulated remains unclear; however, protein complexes such as NELF and DSIF increase pausing whereas the activity of CDK9 (P-TEFb complex) correlates with pause release. To address specific mechanistic questions about pol II pausing and its regulation, we reconstituted human pol II promoter-proximal pausing in vitro, entirely with purified factors (no extracts). As expected, NELF and DSIF increased pol II pausing in vitro, whereas P-TEFb promoted pause release. Unexpectedly, the PIC alone was sufficient to reconstitute pol II pausing, suggesting that pausing is an inherent property of the PIC. In agreement, pol II pausing was lost upon replacement of the TFIID complex with TATA-binding protein (TBP); moreover, pausing was dependent upon TFIID subunits TAF1 and TAF2. TAF1/2 bind genomic DNA downstream of the pol II initiation site, invoking a “complex interaction” model for pausing. Consistent with this model, PRO-Seq experiments revealed increased transcription upon acute depletion (t=60 min) of TAF1 and TAF2 in human cells, and pol II pausing was disrupted at thousands of genes. Similar results were obtained in TAF1-depleted Drosophila S2 cells. Collectively, these data establish the general transcription factor TFIID as a genome-wide regulator of pol II promoter-proximal pausing.
Project description:Many mammalian genes are occupied by paused RNA polymerase II (pol II) at promoter-proximal regions on both sides of transcription start sites (TSSs). However, the consequences of pol II pausing on gene expression and cell biology are not fully understood. Here we report that genetic ablation of the b subunit of mouse negative elongation factor (Nelf-b), a key pol II-pausing factor, results in slower progression at multiple cell cycle stages and increased apoptosis. Consistently, a whole-genome analysis indicates that growth and cell death-related genes are highly enriched among the direct target genes of Nelf-b. In particular, Nelf-b deletion increases pol II density in the promoter-distal region of stress response genes and their overall expression levels in the absence of any external stress signals. In addition, our work also reveals a previously unappreciated role of Nelf-b role in curbing TSS-upstream transcription of many mammalian genes. We suggest that Nelf-mediated pol II pausing balances the cellular needs for growth/survival and stress response by preventing excessive basal transcription of stress-induced genes. Examination of Nelf-b bindings sites on chromosomes in mouse embryonic fibroblasts
Project description:We prepared and sequenced Start-seq libraries from rat (Rattus norgevicus) primary neural progenitor cells. Over 48 million uniquely mappable reads from two independent biological replicates allowed us to define the TSSs of 7,365 known genes in the rn6 genome, reannotating 2,503 TSSs by more than 5 base pairs, characterize promoter-associated antisense transcription, and profile Pol II pausing. By combining TSS data with polyA-selected RNA sequencing, we also identified thousands of potential new genes producing stable RNA as well as non-genic transcripts representing possible regulatory elements. CONCLUSIONS: Our study has produced the first Start-seq dataset for the rat. Apart from profiling transcription initiation, our data reaffirm the prevalence of Pol II pausing across the rat genome and indicate conservation of pausing mechanisms across metazoan genomes. We suggest that pausing location, at least in mammals, is constrained by a distance from initiation of transcription, whether it occurs at or outside of a gene promoter. Abundant antisense transcription initiation around protein coding genes indicates that Pol II recruited to the vicinity of a promoter is distributed to available start sites of transcription at either DNA strand. Transcriptome profiling of neural progenitors presented here will facilitate further studies of other rat cell types as well as other organisms.
Project description:Many mammalian genes are occupied by paused RNA polymerase II (pol II) at promoter-proximal regions on both sides of transcription start sites (TSSs). However, the consequences of pol II pausing on gene expression and cell biology are not fully understood. Here we report that genetic ablation of the b subunit of mouse negative elongation factor (Nelf-b), a key pol II-pausing factor, results in slower progression at multiple cell cycle stages and increased apoptosis. Consistently, a whole-genome analysis indicates that growth and cell death-related genes are highly enriched among the direct target genes of Nelf-b. In particular, Nelf-b deletion increases pol II density in the promoter-distal region of stress response genes and their overall expression levels in the absence of any external stress signals. In addition, our work also reveals a previously unappreciated role of Nelf-b role in curbing TSS-upstream transcription of many mammalian genes. We suggest that Nelf-mediated pol II pausing balances the cellular needs for growth/survival and stress response by preventing excessive basal transcription of stress-induced genes. Immortalized mouse embryonic fibroblasts derived from a Nelf-b flox/- embryo were infected with control or Cre-epxressing retrovirus. Gene expression profile of control and knockout MEF at 7 days after virus infection were compared by using Illumina's mouse whole-genome gene expression BeadChIPs. There are two replicates for both control and knockout MEF samples.
Project description:The highly conserved histone chaperone FACT (Facilitates Chromatin Transcription) is thought to contribute to the disassembly and reassembly of nucleosomes in the wake of RNA Polymerase II (Pol II) passage through chromatin. However, FACT’s roles in chromatin biology and transcriptional regulation in vivo in higher eukaryotes are not well understood. Here, we report that depletion of FACT leads to a reduction in the duration of promoter-proximal pausing by Pol II in Drosophila S2 cells. In addition, FACT depletion leads to a modest decrease in the occupancy of histone H3, and to decrease in occupancy of histone H2A.v in promoter-proximal nucleosomes. Finally, we observed a dramatic 5’ to 3’ repositioning of the co-transcriptionally deposited histone modifications H3K4me3 and H3K36me3 in the FACT depleted cells. Taken together, our findings are consistent with the model that FACT contributes to the interplay between chromatin architecture and control of Pol II promoter-proximal pausing.
Project description:The highly conserved histone chaperone FACT (Facilitates Chromatin Transcription) is thought to contribute to the disassembly and reassembly of nucleosomes in the wake of RNA Polymerase II (Pol II) passage through chromatin. However, FACT’s roles in chromatin biology and transcriptional regulation in vivo in higher eukaryotes are not well understood. Here, we report that depletion of FACT leads to a reduction in the duration of promoter-proximal pausing by Pol II in Drosophila S2 cells. In addition, FACT depletion leads to a modest decrease in the occupancy of histone H3, and to decrease in occupancy of histone H2A.v in promoter-proximal nucleosomes. Finally, we observed a dramatic 5’ to 3’ repositioning of the co-transcriptionally deposited histone modifications H3K4me3 and H3K36me3 in the FACT depleted cells. Taken together, our findings are consistent with the model that FACT contributes to the interplay between chromatin architecture and control of Pol II promoter-proximal pausing.