Similar Datasets
Project description:Transcription and splicing are intricately linked processes, with emerging evidence highlighting the involvement of splicing factors mediating their coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, not only serves as the initial component of the spliceosome but also plays a crucial role in preventing premature cleavage and polyadenylation, facilitating long-distance transcription elongation. Here, we show that U1 snRNP regulates alternative promoter usage through inhibition of premature polyadenylation. Inhibiting U1 snRNP with antisense oligonucleotides or introducing a premature polyadenylation leads to a significant decrease in downstream promoter activity in genes with premature polyadenylation sites in between two promoters. Conversely, restoring U1 snRNP activity or inhibiting premature polyadenylation sites using a gene-specific U1 snRNP rescues downstream promoter activity. Mechanistically, U1 snRNP inhibition correlates with reduced chromatin accessibility and serine 5 phosphorylation levels of RNA polymerase II at downstream promoters. Our findings propose a model where U1 snRNP facilitates productive transcription from upstream promoters, triggering downstream promoter activation by destabilizing nucleosomes and promoting promoter escape.
2025-05-19 | GSE284680 | GEO
Project description:Transcription and splicing are inherently intertwined. Accumulating evidence support a role of splicing factors in mediating this coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, acts as the initial building block of the spliceosome, interacting with nascent pre-mRNA at 5' splice sites. In addition to its role in splicing, U1 snRNP is crucial for preventing premature cleavage and polyadenylation, enabling long-distance transcription elongation. Here, we show that U1 snRNP can regulate the usage of alternative promoters through its role in inhibiting premature polyadenylation. Using antisense oligonucleotides to inhibit U1 snRNP, we first observed a markedly decrease in downstream promoter activity at the newly synthesized RNA level. Interestingly, U1 snRNP inhibition selectively impacts downstream promoters of genes featuring premature polyadenylation sites located between two promoters. Overexpressing a wild-type U1 snRNP or a gene-specific U1 snRNP designed to inhibit premature polyadenylation sites restores downstream promoter activity. Conversely, introducing a premature polyadenylation site between two promoters reduces downstream promoter activity. Exploring the underlying molecular mechanisms, we identified a substantial decrease in serine 5 phosphorylation levels in newly recruited RNA polymerase II at downstream promoters following U1 snRNP inhibition, and reduced chromatin accessibility in the vicinity of downstream promoters. Overall, our model is consistent with productive transcription from upstream promoters triggering downstream promoter activation in the presence of U1 snRNP by destabilizing nucleosomes and promoting promoter escape at downstream promoters.
2025-05-19 | GSE252389 | GEO
Project description:Transcription and splicing are inherently intertwined. Accumulating evidence support a role of splicing factors in mediating this coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, acts as the initial building block of the spliceosome, interacting with nascent pre-mRNA at 5' splice sites. In addition to its role in splicing, U1 snRNP is crucial for preventing premature cleavage and polyadenylation, enabling long-distance transcription elongation. Here, we show that U1snRNP can regulate the usage of alternative promoters through its role in inhibiting premature polyadenylation. Using antisense oligonucleotides to inhibit U1 snRNP, we first observed a markedly decrease in downstream promoter activity at the newly synthesized RNA level. Interestingly, U1 snRNP inhibition selectively impacts downstream promoters of genes featuring premature polyadenylation sites located between two promoters. Overexpressing a wild-type U1 snRNP or a gene-specific U1 snRNP designed to inhibit premature polyadenylation sites restores downstream promoter activity. Conversely, introducing a premature polyadenylation site between two promoters reduces downstream promoter activity. Exploring the underlying molecular mechanisms, we identified a substantial decrease in serine 5 phosphorylation levels in newly recruited RNA polymerase II at downstream promoters following U1 snRNP inhibition, and reduced chromatin accessibility in the vicinity of downstream promoters. Overall, our model is consistent with productive transcription from upstream promoters triggering downstream promoter activation in the presence of U1 snRNP by destabilizing nucleosomes and promoting promoter escape at downstream promoters.
2025-05-19 | GSE252391 | GEO
Project description:Transcription and splicing are inherently intertwined. Accumulating evidence support a role of splicing factors in mediating this coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, acts as the initial building block of the spliceosome, interacting with nascent pre-mRNA at 5' splice sites. In addition to its role in splicing, U1 snRNP is crucial for preventing premature cleavage and polyadenylation, enabling long-distance transcription elongation. Here, we show that U1 snRNP can regulate the usage of alternative promoters through its role in inhibiting premature polyadenylation. Using antisense oligonucleotides to inhibit U1 snRNP, we first observed a markedly decrease in downstream promoter activity at the newly synthesized RNA level. Interestingly, U1 snRNP inhibition selectively impacts downstream promoters of genes featuring premature polyadenylation sites located between two promoters. Overexpressing a wild-type U1 snRNP or a gene-specific U1 snRNP designed to inhibit premature polyadenylation sites restores downstream promoter activity. Conversely, introducing a premature polyadenylation site between two promoters reduces downstream promoter activity. Exploring the underlying molecular mechanisms, we identified a substantial decrease in serine 5 phosphorylation levels in newly recruited RNA polymerase II at downstream promoters following U1 snRNP inhibition, and reduced chromatin accessibility in the vicinity of downstream promoters. Overall, our model is consistent with productive transcription from upstream promoters triggering downstream promoter activation in the presence of U1 snRNP by destabilizing nucleosomes and promoting promoter escape at downstream promoters.
2025-05-19 | GSE252387 | GEO
Project description:Transcription and splicing are intricately linked processes, with emerging evidence highlighting the involvement of splicing factors mediating their coupling. U1 small nuclear ribonucleoprotein particle (U1 snRNP), a key splicing factor, not only serves as the initial component of the spliceosome but also plays a crucial role in preventing premature cleavage and polyadenylation, facilitating long-distance transcription elongation. Here, we show that U1 snRNP regulates alternative promoter usage through inhibition of premature polyadenylation. Inhibiting U1 snRNP with antisense oligonucleotides or introducing a premature polyadenylation leads to a significant decrease in downstream promoter activity in genes with premature polyadenylation sites in between two promoters. Conversely, restoring U1 snRNP activity or inhibiting premature polyadenylation sites using a gene-specific U1 snRNP rescues downstream promoter activity. Mechanistically, U1 snRNP inhibition correlates with reduced chromatin accessibility and serine 5 phosphorylation levels of RNA polymerase II at downstream promoters. Our findings propose a model where U1 snRNP facilitates productive transcription from upstream promoters, triggering downstream promoter activation by destabilizing nucleosomes and promoting promoter escape.
2025-05-19 | GSE284682 | GEO
Project description:U1 snRNP regulates alternative promoter activity by inhibiting premature polyadenylation
| PRJNA1200036 | ENA
Project description:U1 snRNP regulates alternative promoter activity by inhibiting premature polyadenylation
| PRJNA1060322 | ENA
Project description:U1 snRNP regulates alternative promoter activity by inhibiting premature polyadenylation [TT-seq]
| PRJNA1200038 | ENA
Project description:In eukaryotes, U1 small nuclear ribonucleoprotein (snRNP) forms spliceosomes in equal stoichiometry with U2, U4, U5 and U6 snRNPs; however, its abundance in human far exceeds that of the other snRNPs. Here we used antisense morpholino oligonucleotide to U1 snRNA to achieve functional U1 snRNP knockdown in HeLa cells, and identified accumulated unspliced pre-mRNAs by genomic tiling microarrays. In addition to inhibiting splicing, U1 snRNP knockdown caused premature cleavage and polyadenylation in numerous pre-mRNAs at cryptic polyadenylation signals, frequently in introns near (<5 kilobases) the start of the transcript. This did not occur when splicing was inhibited with U2 snRNA antisense morpholino oligonucleotide or the U2-snRNP-inactivating drug spliceostatin A unless U1 antisense morpholino oligonucleotide was also included. We further show that U1 snRNA-pre-mRNA base pairing was required to suppress premature cleavage and polyadenylation from nearby cryptic polyadenylation signals located in introns. These findings reveal a critical splicing-independent function for U1 snRNP in protecting the transcriptome, which we propose explains its overabundance.
| S-EPMC2996489 | biostudies-literature
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.
| S-EPMC3720719 | biostudies-literature