Project description:To understand how U4 snRNP regulates premature cleavage and polyadenylation of pre-mRNAs at the transcriptome wide, we conducted RNAPII ChIP-seq analysis on control, U1 and U4-AMO treated samples.
Project description:To understand how U4 snRNP regulates premature cleavage and polyadenylation of pre-mRNAs at the transcriptome wide, we conducted mRNA-seq analysis on control, U1 and U4-AMO treated HeLa cells
Project description:To understand how U4 snRNP regulates premature cleavage and polyadenylation of pre-mRNAs at the transcriptome wide, we conducted 3'-seq analysis on control, U1 and U4-AMO treated samples using the Lexogen mRNA 3'-seq kit (Cat. 016.24), which enables accurate quantification of global PAS usage.
Project description:The PAF complex (Paf1C) has been shown to regulate chromatin modifications, gene transcription, and PolII elongation. Here, we provide the first genome-wide analysis of chromatin occupancy by the entire PAF complex in mammalian cells. We show that Paf1C is recruited not only to promoters and gene bodies, but also to regions downstream of cleavage/polyadenylation (pA) sites at 3â ends, a profile that sharply contrasted with the yeast complex. Remarkably, our studies identified novel, subunit-specific links between Paf1C and regulation of alternative cleavage and polyadenylation (APA) and upstream antisense transcription. Moreover, we found that depletion of Paf1C subunits also resulted in the accumulation of RNA polymerase II (PolII) over gene bodies, which coincided with APA. Depletion of specific Paf1C subunits leads to global loss of histone H2B ubiquitylation, but surprisingly, there is little impact of Paf1C depletion on other histone modifications, including the tri-methylation of histone H3 on lysines 4 and 36 (H3K4me3 and H3K36me3), previously associated with this complex. Our results provide surprising differences with yeast, while unifying observations that link Paf1C with PolII elongation and RNA processing, and suggest that Paf1C could play a role in protecting transcripts from premature cleavage by preventing PolII accumulation at TSS-proximal pA sites. ChIP-seq, RNA-seq and 3'READS of Paf1C factors in mouse C2C12 myoblast cells
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.
Project description:The PAF complex (Paf1C) has been shown to regulate chromatin modifications, gene transcription, and PolII elongation. Here, we provide the first genome-wide analysis of chromatin occupancy by the entire PAF complex in mammalian cells. We show that Paf1C is recruited not only to promoters and gene bodies, but also to regions downstream of cleavage/polyadenylation (pA) sites at 3’ ends, a profile that sharply contrasted with the yeast complex. Remarkably, our studies identified novel, subunit-specific links between Paf1C and regulation of alternative cleavage and polyadenylation (APA) and upstream antisense transcription. Moreover, we found that depletion of Paf1C subunits also resulted in the accumulation of RNA polymerase II (PolII) over gene bodies, which coincided with APA. Depletion of specific Paf1C subunits leads to global loss of histone H2B ubiquitylation, but surprisingly, there is little impact of Paf1C depletion on other histone modifications, including the tri-methylation of histone H3 on lysines 4 and 36 (H3K4me3 and H3K36me3), previously associated with this complex. Our results provide surprising differences with yeast, while unifying observations that link Paf1C with PolII elongation and RNA processing, and suggest that Paf1C could play a role in protecting transcripts from premature cleavage by preventing PolII accumulation at TSS-proximal pA sites.