Project description:Alternative polyadenylation gives rise to a wide variety of mRNA isoforms with distinct 3' ends; an individual gene can yield many 3' mRNA isoforms and has a typical pattern of poly(A) site use. To identify possible determinants of polyadenylation site distribution, we have used CRISPR to create Saccharomyces cerevisiae strains harboring precise ORF deletions in candidate genes encoding various factors involved in gene expression. We have performed 3' READS to determine the genome-wide pattern of 3' mRNA isoform endpoints in these mutant strains.
Project description:The use of alternative polyadenylation sites is common and affects the post-transcriptional fate of mRNA, including its stability, localization, and translation. Here we use the internal version of our previously developed protocol (PMID: 23295673), to characterize the polyA sites in a xrn1∆ strain.
Project description:Purpose: Quiescence is a state of reversible cell cycle exit. Levels of polyadenylation factors decreases when proliferating cells become quiescent. The goals of this study are to determine the differential use of polyadenylation sites (changes in alternative polyadenylation) in quiescent vs. proliferating cells and also upon knockdown of polyadenylation factors. Methods: Two biological replicates of human dermal fibroblasts (12-1 and 12-3) were used for polyadeylation-site enriched RNA-seq on an Illumina HiSeq 2500 to compare quiescent vs. proliferating cells and polyadenylation factor knockdown vs. control cells. The reads were aligned to the human genome (hg19) uisng Tophat (2.0.14). The resulting bam files were used as an input to a python script provided by Gruber et al. (PMID: 27382025) to determine the counts for each polyadenylation site. Results: We observed a shift toward greater use of distal polyadenylation sites when the fibroblasts entered quiescence. We observed significant overlap between the genes that shift to greater distal site use with quiescence and CstF-64 or CPSF73 knockdown. Conclusions: The shift to greater distal site use with quiescence may reflect in part the reduced levels of cleavage and polyadenylation factors.
Project description:Purpose: To determine genes that undergo alternative polyadenylation in proliferating versus quiescent fibroblasts. Methods: Three different biological replicates (fibroblast strains, 10-1, 12-1, and 12-2) were used for generating proliferating and quiescent (7-day contact inhibited and 7-day serum-starved) cells. RNA extracted from these cells were used for library preparation. cDNA fragments were enriched for the junction between the poly(A) site and the end of the 3' UTR using a modified high throughput sequencing protocol (GnomeGen). cDNA libraries were created according to Gnome-Gen RNA-seq library preparation kit for RNA profiling except Amgen Ampure XP beads were used instead of the Gnome-gen size selector product to remove ligation reaction products before proceeding to the reverse transcription step. The libraries were sequenced on an Illumina HiSeq 2000 instrument. The sequencing reaction wasa run for 147 cycles. Reads from pol(A) enriched cDNA libraries were aligned to the genome using the STAR alignment algorithm after the computational removal of untemplated adenosines. Results: Polyadenylation site selection was significantly altered in approximately 10% of genes in quiescent compared with proliferating fibroblasts. Contact inhibited and serum starved fibroblasts had similar polyadenylation site selection profiles. Conclusions: Quiescence is associated with changes in polyadenylation site selection.
Project description:We conduct herein a systematic study of mRNA recognition and consequent polyadenylation processing of the Arabidopsis mRNA by m6A reader protein CPSF70. Transcriptome-wide characterization of CPSF70-binding sites supporting the recognition m6A-methylated mRNA with CPSF70, and the results of which linked polyadenylation signals recognition. We then perform 3’end sequencing with A-seq2 to identify CPSF70-dependent APA process, showing that CPSF70 modulate m6A–dependent polyadenylation with FUE recognition.
Project description:Alternative cleavage and polyadenylation (APA) results in mRNA isoforms containing different 3’ untranslated regions (3’UTRs) and/or coding sequences. How core cleavage and polyadenylation (C/P) factors regulate APA is not well understood. Using siRNA knockdown coupled with deep sequencing, we found that several C/P factors can play significant roles in 3’UTR-APA. Whereas Pcf11 and Fip1 enhance usage of proximal poly(A) sites (pAs), CFI-25/68, PABPN1, and PABPC1 promote usage of distal pAs. Strong cis element biases were found for pAs regulated by CFI or Fip1, and the distance between pAs plays an important role in APA regulation. In addition, intronic pAs are substantially regulated by splicing factors, with U1 mostly influencing C/P events in 5’ introns and U2 impacting those in efficiently spliced introns. Furthermore, PABPN1 regulates expression of transcripts with pAs near the transcription start site, a property possibly related to its role in RNA degradation. Finally, we found that groups of APA events regulated by C/P factors are also modulated in cell differentiation and development with distinct trends. Together, our results indicate that the abundance of different C/P factors and splicing factors plays diverse roles in APA, and is relevant to APA regulation in biological conditions. knockdown experiments of 23 C/P factors, 3 splicing factors and U1D in mouse C2C12 myoblast cells
Project description:Alternative polyadenylation has been implicated as an important regulator of gene expression. In some cases, alternative polyadenylation is known to couple with alternative splicing to influence last intron removal. However, it is unknown whether alternative polyadenylation events influence alternative splicing decisions at upstream exons. Knockdown of the polyadenylation factors CFIm25 or CstF64 was used as an approach in identifying alternative polyadenylation and alternative splicing events on a genome-wide scale. Although hundreds of alternative splicing events were found to be differentially spliced in the knockdown of CstF64, genes associated with alternative polyadenylation did not exhibit an increased incidence of alternative splicing. These results demonstrate that the coupling between alternative polyadenylation and alternative splicing is usually limited to defining the last exon. The striking influence of CstF64 knockdown on alternative splicing can be explained through its effects on UTR selection of known splicing regulators such as hnRNP A2/B1, thereby indirectly influencing splice site selection. We conclude that changes in the expression of the polyadenylation factor CstF64 influences alternative splicing through indirect effects. HeLa cell line was stably transfected with shRNA plasmids targeting CstF64. Total RNA was isolated from CstF64 KD cells and wild-type control cells using Trizol according to manufacturerâs protocols. Samples were deep sequenced in duplicate using the Illumina GAIIx system.
Project description:The yeast mRNA export adaptor Yra1 binds the Pcf11 subunit of cleavage-polyadenylation factor CF1A linking export to 3'-end formation. We found a surprising consequence of this interaction is that Yra1 influences cleavage-polyadenylation. Yra1 competes with the CF1A subunit, Clp1, for binding to Pcf11, and excess Yra1 inhibits 3' processing in vitro. Release of Yra1 at the 3' ends of genes coincides with recruitment of Clp1, and depletion of Yra1 enhances Clp1 recruitment within some genes. These results suggest that CF1A is not necessarily recruited as a complete unit, but instead Clp1 can be incorporated co-transcriptionally in a process regulated by Yra1. Yra1 depletion causes widespread changes in poly(A) site choice particularly at sites where the efficiency element is divergently positioned. We propose that one way Yra1 modulates cleavage-polyadenylation is by influencing co-transcriptional assembly of the CF1A/B 3' processing factor. Key Words: Yra1, cleavage-polyadenylation, mRNA export, Pcf11, Clp1, Sub2, alternative polyadenylation mRNA poly (A) sites were mapped by sequencing 3' ends in WT and Yra1-depleted cells using a GAL1-YRA1 mutant. RNA seq of mRNA 3' ends using Illumina platform.
Project description:Termination of RNAPII transcription is associated with RNA 3â 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 3â end processing factors, is enriched at the 3â end of genes, and binds RNA motifs downstream of cleavage sites. Importantly, a deficiency in Seb1 resulted in widespread changes in 3â UTR length as a consequence of increased alternative polyadenylation. Given that Seb1 levels affected the recruitment of conserved 3â 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