Project description:MAF1 represses Pol III-mediated transcription by interfering with TFIIIB and Pol III. Herein, we found that MAF1 knockdown induced CDKN1A transcription and chromatin looping concurrently with Pol III recruitment. Simultaneous knockdown of MAF1 with Pol III or BRF1 (subunit of TFIIIB) diminished the activation and looping effect, which indicates that recruiting Pol III was required for activation of Pol II-mediated transcription and chromatin looping. ChIP analysis after MAF1 knockdown indicated enhanced binding of Pol III and BRF1, as well as of CFP1, p300, and PCAF, which are factors that mediate active histone marks, along with the binding of TBP and POLR2E to the CDKN1A promoter. Simultaneous knockdown with Pol III abolished these regulatory events. Similar results were obtained for GDF15. Our results reveal a novel mechanism by which MAF1 and Pol III regulate the activity of a protein-coding gene transcribed by Pol II.
Project description:RNA polymerase (RNA Pol) III synthesizes the tRNAs, the 5S ribosomal RNA and a small number of untranslated RNAs. In vitro, it also transcribes short interspersed nuclear elements (SINEs). We investigated the distribution of RNA Pol III and its associated transcription factors on the genome of mouse embryonic stem (ES) cell using a highly specific tandem ChIP-Seq method. Only a subset of the annotated class-III genes was bound and thus transcribed. A few hundred SINEs were associated with the RNA Pol III transcription machinery. We observed that RNA Pol III and its transcription factors were present at thirty unannotated sites on the mouse genome, only one of which was conserved in human. An RNA was associated with more than 80% of these regions. More than 2200 regions bound by TFIIIC transcription factor were devoid of RNA Pol III. These sites are correlated with association of CTCF and the cohesin. Cohesin has been shown to occupy sites bound by CTCF and to contribute to DNA loop formation associated with gene repression or activation. This observation suggests that TFIIIC may play a role in chromosome organization in mouse. We also investigated the genome-wide distribution of the ubiquitous TFIIS variant, TCEA1. We found that, as in Saccharomyces cerevisiae, TFIIS is associated with class III genes and also with SINEs suggesting that TFIIS is a RNA Pol III transcription factor in mammals. We performed ChIP-seq experiment on mouse ES cells, in order to analyse the distribution of the RNA Pol III, with two of its subunits, RPC1 and RPC4, of the two distinct forms of the transcription factor TFIIIB, with BRF1 and BRF2, respectively subunit of TFIIIB-beta, and TFIIIB-alpha form, and three subunits of the transcription factor TFIIIC, TFIIIC90, TFIIIC110, TFIIIC220. We also analysed the distribution of the RNA Pol II elongation factor TCEA1. We used tagged proteins, in order to develop a highly specific and generic ChIP-seq protocol. A sequence encoding a 6 histidine-Flag-HA tag was inserted just after the last codon of the gene encoding proteins of the RNA Pol III machinery subunits, or just after the start codon for TCEA1, using the recombineering technology. Untagged ES cell line was used as negative control for data processing. Our dataset comprises of ten ChIP-seq samples, eight from tagged proteins, two from untagged cell line.
Project description:Nuclear pores associate with active protein-coding genes in yeast and have been implicated in transcriptional regulation. Here, we show that in addition to transcriptional regulation, key components of C. elegans nuclear pores are required for processing of a subset of small nucleolar RNAs (snoRNAs) and tRNAs transcribed by RNA Polymerase (Pol) III. Chromatin immunoprecipitation of NPP-13 and NPP-3, two integral nuclear pore components, and importin-M-CM-^_ IMB-1, provides strong evidence that this requirement is direct. All three proteins associate specifically with tRNA and snoRNA genes undergoing Pol III transcription. These pore components bind immediately downstream of the Pol III pre-initiation complex, but are not required for Pol III recruitment. Instead, NPP-13 is required for cleavage of tRNA and snoRNA precursors into mature RNAs, whereas Pol II transcript processing occurs normally. Our data suggest that integral nuclear pore proteins act to coordinate transcription and processing of Pol III transcripts in C. elegans. Genome-wide ChIP-seq and ChIP-chip were performed in mixed-stage C. elegans embryos for nuclear pore proteins NPP-13, NPP-3, IMB-1 and chromatin proteins Pol III (RPC-1), TBP-1, TFC-1 (SFC-1), TFC-4 (TAG-315), and Pol II (AMA-1). For RPC-1 and TBP-1 ChIP-seq, embryos depleted for NPP-13 were also used. Total RNAs from wild-type, NPP-13 RNAi, and IMB-1 RNAi embryos were analyzed by RNA-seq.
Project description:Nuclear pores associate with active protein-coding genes in yeast and have been implicated in transcriptional regulation. Here, we show that in addition to transcriptional regulation, key components of C. elegans nuclear pores are required for processing of a subset of small nucleolar RNAs (snoRNAs) and tRNAs transcribed by RNA Polymerase (Pol) III. Chromatin immunoprecipitation of NPP-13 and NPP-3, two integral nuclear pore components, and importin-M-CM-^_ IMB-1, provides strong evidence that this requirement is direct. All three proteins associate specifically with tRNA and snoRNA genes undergoing Pol III transcription. These pore components bind immediately downstream of the Pol III pre-initiation complex, but are not required for Pol III recruitment. Instead, NPP-13 is required for cleavage of tRNA and snoRNA precursors into mature RNAs, whereas Pol II transcript processing occurs normally. Our data suggest that integral nuclear pore proteins act to coordinate transcription and processing of Pol III transcripts in C. elegans. Genome-wide ChIP-seq and ChIP-chip were performed in mixed-stage C. elegans embryos for nuclear pore proteins NPP-13, NPP-3, IMB-1 and chromatin proteins Pol III (RPC-1), TBP-1, TFC-1 (SFC-1), TFC-4 (TAG-315), and Pol II (AMA-1). For RPC-1 and TBP-1 ChIP-seq, embryos depleted for NPP-13 were also used. Total RNAs from wild-type, NPP-13 RNAi, and IMB-1 RNAi embryos were analyzed by RNA-seq.
Project description:RNA polymerase III transcribes many noncoding RNAs (e.g. tRNAs) important for translational capacity and other functions. Here, we localized RNA polymerase III, alternative TFIIIB complexes (BRF1/2) and TFIIIC in HeLa cells, determining the Pol III transcriptome, defining gene classes, and revealing ‘TFIIIC-only’ sites. Pol III localization in other transformed and primary cell lines revealed both novel and cell-type specific Pol III loci, and one occupied miRNA. Surprisingly, only a fraction of the in silico-predicted Pol III loci are occupied. Interestingly, many occupied Pol III genes reside within an annotated Pol II promoter. Outside of Pol II promoters, occupied Pol III genes overlap with enhancer-like chromatin and enhancer binding proteins such as ETS1 and STAT1. Remarkably, Pol III occupancy scales with the levels of nearby Pol II, active chromatin and CpG content. Taken together, active promoter and enhancer-like chromatin appears to gate Pol III accessibility to the genome. Use of ChIP-array to identify genomic regions bound by RNA Polymerase III machinery
Project description:MAF1 represses Pol III-mediated transcription by interfering with TFIIIB and Pol III. Herein, we found that MAF1 knockdown induced CDKN1A transcription and chromatin looping concurrently with Pol III recruitment. Simultaneous knockdown of MAF1 with Pol III or BRF1 (subunit of TFIIIB) diminished the activation and looping effect, which indicates that recruiting Pol III was required for activation of Pol II-mediated transcription and chromatin looping. ChIP analysis after MAF1 knockdown indicated enhanced binding of Pol III and BRF1, as well as of CFP1, p300, and PCAF, which are factors that mediate active histone marks, along with the binding of TBP and POLR2E to the CDKN1A promoter. Simultaneous knockdown with Pol III abolished these regulatory events. Similar results were obtained for GDF15. Our results reveal a novel mechanism by which MAF1 and Pol III regulate the activity of a protein-coding gene transcribed by Pol II. Knockdown assay was performed using siRNA obtained from MISSION®RNA (Sigma). Inhibition of expression of Pol III (SASI_Hs01_00046568) and MAF1 (SASI_Hs01_00135954) was achieved by transfection with LipofectamineTM RNAiMax (Invitrogen) according to the manufacturer’s protocol. MISSION® siRNA Universal Negative Control (Sigma) was used as knockdown control. Cells were transfected in serum-free medium. After 8 h, the siRNA containing medium was replaced with complete medium.
Project description:Epigenetic control is an important aspect of gene regulation. Despite detailed understanding of many examples, the transcription of non-coding RNA genes by RNA polymerase (pol) III is less well characterized. Here we profile the epigenetic features of pol III target genes throughout the human genome. This reveals that the chromatin landscape of pol III-transcribed genes resembles that of pol II templates in many ways, although there are also clear differences. Our analysis also discovered an entirely unexpected phenomenon, namely that pol II co-localizes with the majority of genomic loci that are bound by pol III. Chip-Seq experiments for six samples: Pol III, TFIIIB, TFIIIC, H3K4me3 in HeLa cells and Pol III, S2 phos Pol II in CD4+ cells.
Project description:Nucleosomes restrict the access of transcription factors to chromatin. RSC is a SWI/SNF-family chromatin-remodeling complex from yeast that repositions and ejects nucleosomes in vitro. Here, we examined these activities and their importance in vivo. We utilized array-based methods to examine nucleosome occupancy and positioning at more than 200 locations in the genome following the controlled destruction of the catalytic subunit of RSC, Sth1. Loss of RSC function caused pronounced and general reductions in transcription from Pol I, II, and III genes. At Pol III genes, Sth1 loss conferred a general gain in nucleosome density and an accompanying reduction in RNA Pol III occupancy. In contrast, we observed primarily single nucleosome changes, including movement, at Pol II promoters. Importantly, a greater number of changes were observed near the transcription start sites of RSC-occupied promoters than non-occupied promoters. These changes are distinct from those due to general loss of transcription. Thus, RSC action affects both nucleosome density and positioning in vivo, but applies these remodeling modes differently at Pol II and Pol III genes. Keywords: ChIP-chip, nucleosome, mononucleosome, RSC, transcription
Project description:The packaging of the genetic material into chromatin imposes the remodeling of this barrier to allow efficient transcription. RNA polymerase II activity is associated with several histone modification complexes that enforce remodeling. How RNA polymerase III (Pol III) counteracts the inhibitory effect of chromatin is unknown. We report here that antisense RNA Polymerase II (Pol II) transcription is critical to prime and maintain nucleosome depletion at Pol III loci and allow efficient Pol III recruitment upon re-initiation of growth from stationary phase. Antisense Pol II is recruited by the Pcr1 transcription factor, which affects local histone occupancy through the associated SAGA complex and a Pol II phospho-S2 CTD / Mst2 pathway. These data expand the central role of Pol II in gene expression beyond mRNA synthesis.