U1 snRNP telescripting regulates size-function stratified human genome
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE103252 | GEO | 2017/10/02
SECONDARY ACCESSION(S): PRJNA400626
REPOSITORIES: GEO
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Project description:Full-length transcription in the majority of human genes depends on U1 snRNP (U1) to co-transcriptionally suppress transcription-terminating premature 3’-end cleavage and polyadenylation (PCPA) from cryptic polyadenylation signals (PASs) in introns. However, the mechanism of this U1 activity, termed telescripting, is unknown. Here, we captured a complex, comprising U1 and CPA factors (U1–CPAFs), that binds intronic PASs and suppresses PCPA. U1–CPAFs are distinct from U1-spliceosomal complexes; they include CPA’s three main subunits, CFIm, CPSF, and CstF, lack essential splicing factors, and associate with transcription elongation and mRNA export complexes. Telescripting requires U1:pre-mRNA base-pairing, which can be disrupted by U1 antisense oligonucleotide (U1 AMO), triggering PCPA. U1 AMO remodels U1–CPAFs, revealing changes, including recruitment of CPA-stimulating factors, that explain U1–CPAFs’ switch from repressive to activated states. Our findings outline U1 telescripting mechanism and demonstrate U1’s unique role as central-regulator of pre-mRNA processing and transcription.
2019-07-31 | GSE135140 | GEO
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Project description:Transcription of the mammalian genome is pervasive, but productive transcription outside of protein-coding genes is limited by unknown mechanisms. In particular, although RNA polymerase II (RNAPII) initiates divergently from most active gene promoters, productive elongation occurs primarily in the sense-coding direction. Here we show in mouse embryonic stem cells that asymmetric sequence determinants flanking gene transcription start sites control promoter directionality by regulating promoter-proximal cleavage and polyadenylation. We find that upstream antisense RNAs are cleaved and polyadenylated at poly(A) sites (PASs) shortly after initiation. De novo motif analysis shows PAS signals and U1 small nuclear ribonucleoprotein (snRNP) recognition sites to be the most depleted and enriched sequences, respectively, in the sense direction relative to the upstream antisense direction. These U1 snRNP sites and PAS sites are progressively gained and lost, respectively, at the 5' end of coding genes during vertebrate evolution. Functional disruption of U1 snRNP activity results in a dramatic increase in promoter-proximal cleavage events in the sense direction with slight increases in the antisense direction. These data suggest that a U1-PAS axis characterized by low U1 snRNP recognition and a high density of PASs in the upstream antisense region reinforces promoter directionality by promoting early termination in upstream antisense regions, whereas proximal sense PAS signals are suppressed by U1 snRNP. We propose that the U1-PAS axis limits pervasive transcription throughout the genome. 3' end sequencing of poly (A) + RNAs in mouse ES cells with and without U1 snRNP inhibition using antisense morpholino oligonucleotides (AMO). Each with two biological replicates.
2013-06-28 | E-GEOD-46433 | biostudies-arrayexpress
Project description:Transcription of the mammalian genome is pervasive, but productive transcription outside of protein-coding genes is limited by unknown mechanisms. In particular, although RNA polymerase II (RNAPII) initiates divergently from most active gene promoters, productive elongation occurs primarily in the sense-coding direction. Here we show in mouse embryonic stem cells that asymmetric sequence determinants flanking gene transcription start sites control promoter directionality by regulating promoter-proximal cleavage and polyadenylation. We find that upstream antisense RNAs are cleaved and polyadenylated at poly(A) sites (PASs) shortly after initiation. De novo motif analysis shows PAS signals and U1 small nuclear ribonucleoprotein (snRNP) recognition sites to be the most depleted and enriched sequences, respectively, in the sense direction relative to the upstream antisense direction. These U1 snRNP sites and PAS sites are progressively gained and lost, respectively, at the 5' end of coding genes during vertebrate evolution. Functional disruption of U1 snRNP activity results in a dramatic increase in promoter-proximal cleavage events in the sense direction with slight increases in the antisense direction. These data suggest that a U1-PAS axis characterized by low U1 snRNP recognition and a high density of PASs in the upstream antisense region reinforces promoter directionality by promoting early termination in upstream antisense regions, whereas proximal sense PAS signals are suppressed by U1 snRNP. We propose that the U1-PAS axis limits pervasive transcription throughout the genome.
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Project description:The DNA damage response (DDR) involves coordinated control of gene expression and DNA repair. Using deep sequencing we found widespread changes of alternative cleavage and polyadenylation (APA) site usage upon UV-treatment in mammalian cells. APA regulation in the 3’ untranslated region (3’UTR) is substantial, leading to both shortening and lengthening of 3’UTRs. Interestingly, a strong activation of intronic APA sites is detected, resulting in widespread expression of truncated transcripts. Intronic APA events are biased to the 5’ end of genes and affect gene groups with important functions in DDR. Moreover, intronic APA site activation during DDR correlates with a decrease in U1 snRNA levels, and this is reversed by U1 snRNA overexpression. Importantly, U1 snRNA overexpression decreases UV-induced apoptosis. Together, these studies describe a significant gene regulatory scheme in DDR where U1 snRNP impacts gene expression via APA.
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Project description:Pervasive transcription in the mammalian genome produces thousands of long noncoding RNAs (lncRNAs) and promoter- or enhancer-associated unstable transcripts. They preferentially locate to chromatin, at which some regulate chromatin structure, transcription and RNA processing. While several RNA sequences responsible for nuclear localization have been identified, such as repeats in the lncRNA Xist and Alu-like elements for long RNAs, how lncRNAs as a class are enriched on chromatin remains elusive. To screen for cis-elements that contribute to RNA-chromatin localization, we developed a high-throughput method named RNA elements for subcellular localization by sequencing (REL-seq), and discovered a U1 small nuclear ribonucleoprotein (snRNP)-recognition motif being critical for chromatin localization of reporter RNAs. Across the genome, chromatin-bound lncRNAs, which are enriched with 5’ splice sites and depleted of 3’ splice sites, exhibit high levels of U1 snRNA binding compared to cytoplasm-localized protein-coding mRNAs. Acute depletion of U1 snRNA, or U1 snRNP protein component SNRNP70, drastically reduces the chromatin association of hundreds of lncRNAs and unstable transcripts without altering the overall transcription rate in cells. In addition, rapid degradation of SNRNP70 reduces the localization of both nascent and polyadenylated lncRNA transcripts to chromatin, and disrupts the nuclear-speckles and genome-wide localization of Malat1, a highly conserved and abundant lncRNA. Moreover, chromatin-bound U1 snRNP interacts with transcriptionally engaged RNA polymerase (Pol) II. Together, these results demonstrate that U1 snRNP acts widely to tether and mobilize lncRNAs to chromatin in a Pol II transcription-dependent manner. Our findings uncover a novel role of U1 snRNP beyond pre-mRNA processing and provide molecular insights into how lncRNAs are recruited to Pol II-transcribed genes and have a propensity for chromatin-associated functions.
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Project description:Regulation of RNA polymerase II (Pol II) elongation is a critical step in gene regulation. Here, we report that U1 snRNP recognition and transcription pausing at stable nucleosomes are linked through premature polyadenylation signal (PAS) termination. By generating RNA exosome conditional deletion mouse embryonic stem cells, we identified a large class of polyadenylated short transcripts in the sense direction destabilized by the RNA exosome. These PAS termination events are enriched at the first few stable nucleosomes flanking CpG islands and suppressed by U1 snRNP. Thus, promoter-proximal Pol II pausing consists of two processes: TSS-proximal and +1 stable nucleosome pausing, with PAS termination coinciding with the latter. While pausing factors NELF/DSIF only function in the former step, flavopiridol-sensitive mechanism(s) and Myc modulate both steps. We propose that premature PAS termination near the nucleosome-associated pause site represents a common transcriptional elongation checkpoint regulated by U1 snRNP recognition, nucleosome stability, and Myc activity.
2018-02-01 | GSE100536 | GEO
Project description:Regulation of RNA polymerase II (Pol II) elongation is a critical step in gene regulation. Here, we report that U1 snRNP recognition and transcription pausing at stable nucleosomes are linked through premature polyadenylation signal (PAS) termination. By generating RNA exosome conditional deletion mouse embryonic stem cells, we identified a large class of polyadenylated short transcripts in the sense direction destabilized by the RNA exosome. These PAS termination events are enriched at the first few stable nucleosomes flanking CpG islands and suppressed by U1 snRNP. Thus, promoter-proximal Pol II pausing consists of two processes: TSS-proximal and +1 stable nucleosome pausing, with PAS termination coinciding with the latter. While pausing factors NELF/DSIF only function in the former step, flavopiridol-sensitive mechanism(s) and Myc modulate both steps. We propose that premature PAS termination near the nucleosome-associated pause site represents a common transcriptional elongation checkpoint regulated by U1 snRNP recognition, nucleosome stability, and Myc activity.
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