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.
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.
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.
Project description:Here we report high-resolution analyses of transcribing RNAPIII in either a wild-type (WT) background , a sen1-3 mutant or a Sen1 auxin-inducible degron (AID) strain in which Sen1 can be rapidly depleted upon addition of the auxin analogue Indole-3-acetic acid (IAA). Sen1 is a well-characterized transcription termination factor for RNAPII-dependent genes in budding yeast. Here we show that the presence of three point mutations in sen1-3 that abrogate the interaction of Sen1 with RNAPIII, as well as the depletion of Sen1 provoke global transcription termination defects at RNAPIII-dependent genes. These results indicate that Sen1 is also a transcription termination factor for RNAPIII transcription units.
Project description:Manuscript title: Modulated termination of non-coding transcription partakes in the regulation of gene expression Here we report high-resolution analyses of transcribing RNAPII in either a wild-type (WT) background or a sen1T1623E mutant, which harbours a substitution that mimics the phosphorylation at threonine 1623. Sen1 is a well-characterized transcription termination factor for RNAPII-dependent non-coding genes in budding yeast. Here we show that the T1623E phosphomimetic mutation induces moderate but widespread termination defects at target non-coding genes, strongly suggesting that phosphoryation at T1623 modulates negatively Sen1 transcription termination activity.
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:R-loop disassembly by the human helicase Senataxin contributes to genome stability and to proper transcription termination at a subset of RNA polymerase II genes. Whether Senataxin-mediated R-loop disassembly also contributes to transcription termination at other classes of genes has remained unclear. Here we show that Sen1, one of two fission yeast homologues of Senataxin, promotes efficient termination of RNA Polymerase III (RNAP3) transcription in vivo. In the absence of Sen1, RNAP3 accumulates downstream of the primary terminator at RNAP3-transcribed genes and produces long exosome-sensitive 3’-extended transcripts. Importantly, neither of these defects was affected by the removal of R-loops. The finding that Sen1 acts as an ancillary factor for RNAP3 transcription termination in vivo challenges the pre-existing view that RNAP3 terminates transcription autonomously. We propose that Sen1 is a cofactor for transcription termination that has been co-opted by different RNA polymerases in the course of evolution.
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.