Project description:Recent studies have found that promoter-proximal pausing occurs at most Pol2-regulated genes. DSIF and NELF function as negative elongation factors and promote Pol2 pausing. P-TEFb, whose enzymatic activity lies in the kinase Cdk9, positively regulates the transition into productive elongation by phosphorylating subunits in DSIF, NELF and Pol2. To gain insights into the interplay between these factors in regulating transcriptional pause release, we tested if knockdown of either pausing factor could bypass P-TEFb function. We find that P-TEFb function is still required for transcriptional elongation after DSIF or NELF knockdown. mES cells were infected with a shRNA hairpin to knockdown Spt5, Spt4, NelfE or control. The resulting cells were then treated with flavopiridol (1uM for 60 minutes). DNA was enriched by chromatin immunoprecipitation (ChIP) and analyzed by Solexa sequencing. A sample of whole cell extract was sequenced and used as the background to determine enrichment. ChIP was performed using an antibody against total RNA Pol2 (Rpb1 N-terminus, Santa Cruz sc-899).
Project description:Recent studies have found that promoter-proximal pausing occurs at most Pol2-regulated genes. DSIF and NELF function as negative elongation factors and promote Pol2 pausing. P-TEFb, whose enzymatic activity lies in the kinase Cdk9, positively regulates the transition into productive elongation by phosphorylating subunits in DSIF, NELF and Pol2. To gain insights into the interplay between these factors in regulating transcriptional pause release, we tested if knockdown of either pausing factor could bypass P-TEFb function. We find that P-TEFb function is still required for transcriptional elongation after DSIF or NELF knockdown.
Project description:Most metazoan promoters have RNA polymerase II (Pol II) paused slightly downstream of the transcription start site by NELF and DSIF. This pausing keeps these promoters available for rapid induction by P-TEFb, whose activity causes NELF to dissociate and Pol II and DSIF to elongate on the gene. ChIP-Seq data was generated for Pol II, NELF, and DSIF in HeLa cells and used to look at pausing downstream of unannotated promoters. 3x ChIP-Seq (Pol II, NELF, DSIF) in HeLa cells
Project description:Most metazoan promoters have RNA polymerase II (Pol II) paused slightly downstream of the transcription start site by NELF and DSIF. This pausing keeps these promoters available for rapid induction by P-TEFb, whose activity causes NELF to dissociate and Pol II and DSIF to elongate on the gene. ChIP-Seq data was generated for Pol II, NELF, and DSIF in HeLa cells and used to look at pausing downstream of unannotated promoters.
Project description:FIT-039 is a novel antiviral compound. Antiviral mechanism of FIT-039 is the inhibition of the viral transcription through suppression of the CTD phosphorylation of RNA polymerase II. We used microarrays to evaluated the effect of FIT-039 on host cellular transcriptome, compared with Flavopiridol which is an existing pan-specific CDK9 inhibitor. HeLa cells were incubated with FIT-039 or flavopiridol at the concentration of IC80 for 24 hr, and cellular RNAs were collected and subjected to microarray analysis. The solvent DMSO was used as a negative control.
Project description:Cdk9 is an essential transcriptional kinase that is conserved across distant eukaryotes, but we previously found that acute inhibition of Cdk9 causes different transcriptional phenotypes in NELF-containing higher eukaryotes (like mammals and Drosophila) vs. the NELF-lacking fission yeast S. pombe. NELF is known to participate in promoter-proximal pausing of RNA Polymerase II, and using NELF-depleted Drosophila cells, we find that this NELF-mediated pause is necessary to prevent gene body entry by Pol II in the absence of Cdk9. Without NELF, the abnormal gene body entry that occurs following Cdk9 inhibition is strikingly similar to that seen in S. pombe, and in either case, these Pol II complexes have elongation defects and are unable to complete gene transcription. These results show that NELF enforces an early checkpoint for Cdk9 and efficiently shuts down gene transcription in its absence. We propose this would have been critical for the emergence of gene regulatory strategies acting via Cdk9 to modulate transcription of specific genes.
Project description:According to previous studies, during Drosophila embryogenesis, RNA polymerase II is recruited to promoters at developmental stages preceding the stages of active transcription of genes. This work is aimed at exploring whether this mechanism is used during Drosophila metamorphosis. We performed ChIP-Seq analysis using antibodies to various modifications of RNA polymerase II (total, Pol II CTD Ser5P and Pol II CTD Ser2P), as well as to subunits of NELF, DSIF, PAF complexes and Brd4/Fs(1)h that control transcription elongation. We found that like in mid-embryogenesis during metamorphosis, promoters bind RNA polymerase II in the "paused" state preparing for activation at later stages of development. During mid-embryogenesis, RNA polymerase II in "pause" is phosphorylated at Ser5 and Ser2 of Rpb1 CTD and binds NELF, DSIF, and PAF complexes, but not Brd4/Fs(1)h. During metamorphosis, the "paused" RNA polymerase II complex includes Brd4/Fs(1)h in addition to NELF, DSIF, and PAF. The RNA polymerase II in this complex is phosphorylated at Ser5 at Rpb1 CTD, but not at Ser2.
Project description:FIT-039 is a novel antiviral compound. Antiviral mechanism of FIT-039 is the inhibition of the viral transcription through suppression of the CTD phosphorylation of RNA polymerase II. We used microarrays to evaluated the effect of FIT-039 on host cellular transcriptome, compared with Flavopiridol which is an existing pan-specific CDK9 inhibitor.
Project description:Release of promoter-proximal paused RNA polymerase II (Pol II) during early elongation is a critical step in transcriptional regulation in metazoan cells. Paused Pol II release is thought to require the kinase activity of cyclin-dependent kinase 9 (CDK9) for the phosphorylation of DRB sensitivity-inducing factor, negative elongation factor, and C-terminal domain (CTD) serine-2 of Pol II. We found that Pol II-associated factor 1 (PAF1) is a critical regulator of paused Pol II release, that positive transcription elongation factor b (P-TEFb) directly regulates the initial recruitment of PAF1 complex (PAF1C) to genes, and that the subsequent recruitment of CDK12 is dependent on PAF1C. These findings reveal cooperativity among P-TEFb, PAF1C, and CDK12 in pausing release and Pol II CTD phosphorylation. Comparison of the chromatin occupancy of [1] PAF1, CDC73, LEO1, CTR9, total Pol II, and CTD serine 2-phosphorylated Pol II by ChIP-seq in THP1 cells; [2] PAF1, Pol II, Pol II (ser-5p), CDK12, and CDK9 by ChIP-seq in control and PAF1 knockdown cells; [3] LEO1 and Pol II by ChIP-seq in control and flavopiridol treated THP1 cells.
Project description:Using ChIP-Seq, we show that hydrogen peroxide causes rapid accumulation of Pol II at promoters and enhancers. Over time, a fraction of accumulated Pol II loses NELF and creeps downstream. In GSE100740, we also compared nuclear walk-on results with PRO-Seq, both of which were performed using nuclei from DMSO- and flavopiridol-treated cells.