The Sen1 Helicase Prevents Spurious Transcription by Controlling Genome-Wide Transcription Termination by RNAPII
ABSTRACT: RNA Polymerase II (RNAPII) termination for transcripts containing a polyadenylation signal (PAS) is thought to differ mechanistically from termination for PAS-independent RNAPII transcripts such as sn(o)RNAs. In a screen for factors required for PAS-dependent termination, we identified Sen1, a putative helicase known primarily for its role in PAS-independent termination. We show that Sen1 is required for termination on hundreds of protein-coding genes and suppresses cryptic transcription from nucleosome-free regions on a genomic scale. These effects often overlap with but are also often distinct from those caused by Nrd1 depletion, which also impacts termination of protein-coding and cryptic transcripts, including many genic antisense transcripts. Sen1 controls termination through its helicase activity and stimulates recruitment of factors previously implicated in both PAS-dependent (Rna14, Rat1) and PAS-independent (Nrd1) termination. Thus, RNAPII termination for both protein-coding genes and cryptic transcripts is dependent on multiple pathways. Overall design: The 2 RNAPII datasets were produced in duplicates and the Sen1 and Nrd1 datasets in triplicates (all IP/Input).
Project description:RNA Polymerase II (RNAPII) termination for transcripts containing a polyadenylation signal (PAS) is thought to differ mechanistically from termination for PAS-independent RNAPII transcripts such as sn(o)RNAs. In a screen for factors required for PAS-dependent termination, we identified Sen1, a putative helicase known primarily for its role in PAS-independent termination. We show that Sen1 is required for termination on hundreds of protein-coding genes and suppresses cryptic transcription from nucleosome-free regions on a genomic scale. These effects often overlap with but are also often distinct from those caused by Nrd1 depletion, which also impacts termination of protein-coding and cryptic transcripts, including many genic antisense transcripts. Sen1 controls termination through its helicase activity and stimulates recruitment of factors previously implicated in both PAS-dependent (Rna14, Rat1) and PAS-independent (Nrd1) termination. Thus, RNAPII termination for both protein-coding genes and cryptic transcripts is dependent on multiple pathways. The 2 RNAPII datasets were produced in duplicates and the Sen1 and Nrd1 datasets in triplicates (all IP/Input).
Project description:It is currently believed that termination by RNAPII occurs differently depending whether a transcript contains or lacks a polyadenylation signal (PAS). By screening for factors deficient for PAS-dependent termination in an in vivo reporter assay, we identified Sen1, a putative helicase mainly known for its role in PAS-independent termination of snoRNAs. We show for the first time that Sen1 regulates transcription termination at protein-encoding genes genome-wide. As well, we show that Sen1 suppresses cryptic transcription genome-wide, besides being required for termination of most snoRNAs. We provide evidence that Sen1 controls termination through its helicase activity and by effectively recruiting to chromatin, factors implicated in PAS-dependent (Rna14 and Rat1) or PAS-independent termination (Nrd1). Importantly, we demonstrate that the effect on transcription termination of Sen1 and Nrd1, although similar, differ quantitatively and qualitatively. Our results suggest that in yeast, termination by RNAPII at protein encoding-genes makes use of redundant pathways. Overall design:  Expression profiling: Genome-wide expression profiling in Sen1 and Nrd1 mutants was performed using Affymetrix tiling microarrays. Termination defects and cryptic transcription were then assessed in pairwise comparisons with wild-type strains that were grown and assayed under the same conditions.  Nucleosome profiling: The supplemental CEL files contain the raw hybridization signals from genome-wide nucleosome occupancy experiments in a SEN1tetO7 and a wild type strain. The .BAR files contain the normalized data for each mutant and wild-type compared to the total genomic DNA signal to identify nucleosome occupancy patterns.
Project description:RNAPII is responsible for transcription of protein-coding genes and short, regulatory RNAs. In Saccharomyces cerevisiae, termination of RNAPII-transcribed RNAs ≤1000 bases requires the NNS complex (comprised of Nrd1, Nab3, and Sen1) processing by the exosome, and the nuclear specific catalytic subunit, Rrp6. It has been shown that Rrp6 interacts directly with Nrd1, but whether or not Rrp6 is required for NNS-dependent termination is unclear. Loss of Rrp6 function may result in extension (or inhibition of termination) of NNS-dependent transcripts, or Rrp6 may only function after the fact to carry out RNA 3’ end processing. Here, we performed in-depth differential expression analyses and compare RNA-sequencing data of transcript length and abundance in cells lacking RRP6 to previously published sequencing data measuring the length of RNAs in Nrd1-depleted cells. We find many transcripts that were defined as unterminated upon loss of Nrd1 activity are of similar length in rrp6Δ, and expression levels of downstream genes are significantly decreased. This suggests a similar transcription interference mechanism occurs in cells lacking either Nrd1 or Rrp6, supporting the hypothesis that Rrp6 activity is required for proper NNS termination in vivo. Four biological replicates each for deletion mutant (RRP6) and reference cells (WT)
Project description:Here we analysed the role of yeast Senataxin (Sen1) in coordinating replication with transcription and in protecting genome integrity. Senataxin is mutated in the two severe neurodegenerative diseases AOA2 and ALS4. We show that a fraction of Sen1/Senataxin DNA/RNA helicase associates with replication forks and protects the integrity of those fork encountering highly expressed RNAPII genes. sen1 mutants accumulate aberrant DNA structures and RNA-DNA hybrids while forks clash head-on with RNAPII transcription units and counteract recombinogenic events and accumulation of checkpoint signals. Nrd1, which acts togheter with Sen1 in trascription temination, is not recruited at replication forks. nrd1 mutants does not display replication defects, high genome instability and checkpoint activation observed in sen1 mutants The Sen1 function in replication can be therefore separable from its role in RNA processing. We propose a role for Sen1/Senataxin during chromosome replication in facilitating replisome progression across RNAPII transcribed genes thus preventing DNA-RNA hybrids accumulation when forks encounter nascent transcripts on the lagging strand template. Chip on chip analysis was carried out as described (Bermejo et al., 2011), employing anti-Flag monoclonal antibody M2 (Sigma-Aldrich) Labelled probes were hybridized to Affymetrix S.cerevisiae Tiling 1.0 (P/N 900645) arrays and processed with TAS software.
Project description:Termination of RNAPII transcription is associated with RNA 3’ end formation. For coding genes, termination is initiated by the cleavage/polyadenylation machinery. In contrast, a majority of noncoding transcription events in S. cerevisiae do not rely on RNA cleavage for termination, but instead terminate via a pathway that requires the Nrd1-Nab3-Sen1 (NNS) complex. Here we show that the S. pombe ortholog of Nrd1, Seb1, does not function in NNS-like termination, but promotes polyadenylation site selection of coding and noncoding genes. We found that Seb1 associates with 3’ end processing factors, is enriched at the 3’ end of genes, and binds RNA motifs downstream of cleavage sites. Importantly, a deficiency in Seb1 resulted in widespread changes in 3’ UTR length as a consequence of increased alternative polyadenylation. Given that Seb1 levels affected the recruitment of conserved 3’ end processing factors, our findings indicate that the conserved RNA-binding protein Seb1 co-transcriptionally controls alternative polyadenylation. Two biological replicates of Seb1 and Control (parental strain) CRAC experiments
Project description:Termination of yeast RNA polymerase II (Pol II) transcripts occurs through two alternative pathways. Termination of mRNAs is coupled to cleavage and polyadenylation while non-coding transcripts are terminated through the Nrd1-Nab3-Sen1 (NNS) pathway in a process that is linked to RNA degradation by the nuclear exosome. Some mRNA transcripts are also attenuated through premature termination directed by the NNS complex. In this paper we present the results of nuclear depletion of the NNS component Nab3. As expected many non-coding RNAs fail to terminate properly. In addition, we observe that nitrogen catabolite repressed genes are up-regulated by Nab3 depletion. Overall design: Yeast Pol II genome wide positioning before and after Nab3-FRB tagged nuclear depletion using Illumina HI-Seq
Project description:In Saccharomyces cerevisiae, Sen1 is a 252-kDa, nuclear superfamily-1 RNA/DNA helicase that encoded by an essential gene SEN1 (Senataxin). It is an important component of the Nrd1p-Nab3p-Sen1p (NRD1) complex that regulates the transcriptional termination of most non-coding and some coding transcripts at RNA polymerase pause sites. Sen1 specifically interacts with Rnt1p (RNase III), an endoribonuclease, and with Rpb1p (Rpo21p), a subunit of RNA polymerase II, through its N-terminal domain (NTD), which is a critical element of the RNA-processing machinery. Moreover, mutations in the N-terminal tail of SETX, a human ortholog of yeast Senataxin (Sen1) reported in neurological disorders. In one of the earlier studies, we have reported that the loss of dispensable NTD in yeast Sen1 resulted in flocculation and slow growing phenotypes along with defective DNA damage repair mechanisms. So, we attempted to explore the molecular basis of functional impairment associated with the loss of Sen1 N-terminal domain through global oligonucleotide microarray analysis. Also, we investigated for functionally enriched pathways based on the altered basal level gene expression profiles upon NTD loss of Sen1. The microarray data were validated by quantitative real-time PCR wherever necessary. Overall design: Wild-type (BY4741) and Sen1ΔN mutant yeast cells were inoculated to an OD600 of 0.4 in fresh synthetic complete liquid media and then the cells were further allowed to grow until reaches to exponential phase (OD600-1.5). Two independent experiments were performed for each experiment (WT or Sen1ΔN). Total RNAs were extracted and hybridized on Affymetrix microarrays.
Project description:In Saccharomyces cerevisiae short non-coding RNA (ncRNA) generated by RNA Polymerase II (Pol II) are terminated by the NRD complex consisting of Nrd1, Nab3 and Sen1. We now show that Pcf11, a component of the cleavage and polyadenylation complex (CPAC), is generally required for NRD-dependent transcription termination through the action of its CTD interacting domain (CID). Pcf11 localizes downstream of Nrd1 on NRD terminators, and its recruitment depends on Nrd1. Furthermore mutation of the Pcf11 CID results in Nrd1 retention on chromatin, delayed degradation of ncRNA and restricts Pol II CTD Ser2 phosphorylation and Sen1-Pol II interaction. Finally, the pcf11-13 and sen1-1 mutant phenotypes are very similar as both accumulate RNA:DNA hybrids and display Pol II pausing downstream of NRD terminators. We predict a mechanism whereby Nrd1 and Pcf11 exchange on chromatin facilitates Pol II pausing and CTD Ser2-P phosphorylation. This in turn promotes Sen1 activity that is required for NRD-dependent transcription termination in vivo. ChIP-seq with antibody against pol II in wild type and Pcf11 mutants: Pcf11-2, Pcf11-9 and Pcf11-13 grown at 25C and 37C along with input samples
Project description:We report here the transcriptome-wide distribution of yeast Rpb2, Sen1, Nrd1 and Nab3 binding sites. These data sets provide highresolution definition of non-poly(A) terminators, identify novel genes regulated by attenuation of nascent transcripts close to the promoter, and demonstrate the widespread occurrence of Nrd1-bound 3'-antisense transcripts on genes that are poorly expressed. In addition, we show that Sen1 does not cross-link to many expected ncRNAs but surprisingly binds to pre-mRNA transcripts suggesting a role in 3' end formation and/or termination. Six samples by adaptation of PAR-ClIP procedure
Project description:Using a modification of the yeast anchor away and PAR-CLIP protocols, we have mapped the position of Pol II genome-wide in living yeast cells after depletion of components of either the polyadenylation (pA) or non-pA termination complexes. Depletion of Ysh1 from the nucleus does not lead to readthrough transcription. In contrast, depletion of the termination factor Nrd1 leads to widespread runaway elongation of non-pA transcripts. Depletion of Sen1 also leads to readthrough at non-pA terminators but in contrast to Nrd1 this readthrough appears less processive. Examination of PAR-CLIP sequencing data of Pol II after removal of different transcriptional termination factors.