PolyA Sequencing of K562 Cells
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE145400 | GEO | 2021/08/04
REPOSITORIES: GEO
Similar Datasets
Project description:Analogous to alternative splicing, alternative polyadenylation (APA) has long been thought to result from competition between proximal and distal polyA sites. By Fractionation-seq, we unexpectedly identified several hundred APA genes where their distal polyA isoforms are retained in chromatin/nuclear matrix and proximal polyA isoforms released into the cytoplasm. Global metabolic PAS-seq and Nanopore long-read RNA-seq provided further evidence that the strong distal polyA sites are first processed and the resulting transcripts are anchored in chromatin/nuclear matrix for further processing at proximal polyA sites and removal of certain slowly spliced introns. By engineering an autocleavable ribozyme between the proximal and distal polyA sites, we demonstrated that the distal polyA isoform is indeed the precursor to the proximal polyA isoform. Therefore, unlike alternative splicing, APA sites are recognized independently, rather than competitively, and in many cases, in a sequential manner. This provides a versatile strategy to regulate gene expression in mammalian cells.
2021-11-26 | GSE165742 | GEO
Project description:The tumorigenesis of small intestinal neuroendocrine tumors (NETs) is poorly understood. Recent studies have associated alternative polyadenylation with proliferation, cell transformation and cancer. Polyadenylation is the process in which the pre-mRNA is cleaved at a polyA site and a polyA tail is added. Genes with two or more polyA sites can undergo alternative polyadenylation. This produces two or more distinct mRNA isoforms with different 3M-bM-^@M-^Y untranslated regions. Additionally, alternative polyadenylation can also produce mRNAs containing different 3M-bM-^@M-^Y-terminal coding regions. Therefore, alternative polyadenylation alters both the repertoire and the expression level of proteins. Here we used high-throughput sequencing data to map polyA sites and characterize polyadenylation genome-wide in three small intestinal neuroendocrine tumors and a reference sample. In the tumors sixteen genes showed significant changes of alternative polyadenylation pattern, which lead to either the 3M-bM-^@M-^Y truncation of mRNA coding regions or 3M-bM-^@M-^Y untranslated regions. Among these, 11 genes had been previously associated with cancer, with 4 genes being known tumor suppressors: DCC, PDZD2, MAGI1 and DACT2. We validated the alternative polyadenylation in 3 out of 3 cases with Q-RT-PCR. Our findings suggest that changes of alternative polyadenylation pattern in these 16 genes could be involved in the tumorigenesis of small intestinal neuroendocrine tumors. Furthermore, they also point to alternative polyadenylation as a new target for both diagnostic and treatment of small intestinal neuroendocrine tumors. The identified genes with alternative polyadenylation specific to the small intestinal neuroendocrine tumors could be further tested as diagnostic markers and drug targets for disease prevention and treatment. PolyA-seq profiling of 3 human neuroendocrine tumors compared and pituitary using Direct RNA Sequencing from Helicos Biosciences Technology
2014-04-10 | E-GEOD-56657 | biostudies-arrayexpress
Project description:The tumorigenesis of small intestinal neuroendocrine tumors (NETs) is poorly understood. Recent studies have associated alternative polyadenylation with proliferation, cell transformation and cancer. Polyadenylation is the process in which the pre-mRNA is cleaved at a polyA site and a polyA tail is added. Genes with two or more polyA sites can undergo alternative polyadenylation. This produces two or more distinct mRNA isoforms with different 3’ untranslated regions. Additionally, alternative polyadenylation can also produce mRNAs containing different 3’-terminal coding regions. Therefore, alternative polyadenylation alters both the repertoire and the expression level of proteins. Here we used high-throughput sequencing data to map polyA sites and characterize polyadenylation genome-wide in three small intestinal neuroendocrine tumors and a reference sample. In the tumors sixteen genes showed significant changes of alternative polyadenylation pattern, which lead to either the 3’ truncation of mRNA coding regions or 3’ untranslated regions. Among these, 11 genes had been previously associated with cancer, with 4 genes being known tumor suppressors: DCC, PDZD2, MAGI1 and DACT2. We validated the alternative polyadenylation in 3 out of 3 cases with Q-RT-PCR. Our findings suggest that changes of alternative polyadenylation pattern in these 16 genes could be involved in the tumorigenesis of small intestinal neuroendocrine tumors. Furthermore, they also point to alternative polyadenylation as a new target for both diagnostic and treatment of small intestinal neuroendocrine tumors. The identified genes with alternative polyadenylation specific to the small intestinal neuroendocrine tumors could be further tested as diagnostic markers and drug targets for disease prevention and treatment.
2014-04-10 | GSE56657 | GEO
Project description:Sequencing of the 3â end of poly(A)+ RNA identifies cleavage and polyadenylation sites (pAs) and measures transcript expression. We previously developed a method, 3â region extraction and deep sequencing (3âREADS), to address mispriming issues that often plague 3â end sequencing. Here we report a new version, named 3âREADS+, which has vastly improved accuracy and sensitivity. Using a special locked nucleic acid oligo to capture poly(A)+ RNA and to remove bulk of the poly(A) tail, 3âREADS+ generates RNA fragments with an optimal number of terminal As that balance data quality and detection of genuine pAs. With improved RNA ligation steps for efficiency, the method shows much higher sensitivity (over two orders of magnitude) compared to the previous version. Using 3âREADS+, we have uncovered a sizable fraction of previously overlooked pAs located next to or within a stretch of adenylate residues in human genes, and more accurately assessed the frequency of alternative cleavage and polyadenylation (APA) in HeLa cells (~50%). 3âREADS+ will be a useful tool to accurately study APA and to analyze gene expression by 3â end counting, especially when the amount of input total RNA is limited. Nine 3'READS+ libraries were made with different amounts (100 ng, 200 ng, 400 ng, 1000 ng, 5000 ng, 15000 ng) of input Hela RNA.
2016-08-14 | E-GEOD-84170 | 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. 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:Polyadenylation of nascent RNA by poly(A) polymerase (PAP) is important for 3’ end maturation of almost all eukaryotic mRNAs. Most mammalian genes harbor multiple polyadenylation sites (PASs), leading to expression of alternative polyadenylation (APA) isoforms with distinct functions. How poly(A) polymerases may regulate PAS usage and hence gene expression is poorly understood. Here we show that the nuclear canonical (PAPalpha and PAPgamma) and non-canonical (Star-PAP) PAPs play diverse roles in PAS selection and gene expression. Deficiencies in the PAPs resulted in perturbations of gene expression, with Star-PAP impacting lowly expressed mRNAs and long-noncoding RNAs to the greatest extent. Importantly, different PASs of a gene are distinctly regulated by different PAPs, leading to widespread relative expression changes of APA isoforms. The location and surrounding sequence motifs of a PAS appear to differentiate its regulation by the PAPs. We show Star-PAP-specific PAS usage regulates the expression of the eukaryotic translation initiation factor EIF4A1, the tumor suppressor gene PTEN, and the long non-coding RNA NEAT1. The Star-PAP-mediated APA of PTEN is essential for DNA damage-induced increase of PTEN protein levels. Together, our results reveal a PAS-guided and PAP-mediated paradigm for gene expression in response to cellular signaling cues.
2017-06-19 | GSE84461 | GEO
Project description:Cleavage and polyadenylation is essential for 3’ end processing of almost all eukaryotic mRNAs. Recent studies have shown widespread alternative cleavage and polyadenylation (APA) events leading to mRNA isoforms with different 3’UTRs and/or coding sequences. Here we present a compendium of conserved cleavage and polyadenylation sites (PASs) in mammalian genes, based on ~1.2 billion 3’ end sequencing reads from over 360 human, mouse and rat samples. We show that ~80% of mammalian mRNA genes contain at least one conserved PAS, and ~50% have conserved APA events. PAS conservation generally reduces promiscuous 3’ end processing, stabling gene expression levels across species. Conservation of APA correlates with gene age, gene expression features, and gene functions. Genes with certain functions, such as cell morphology, cell proliferation, and mRNA metabolism, are particularly enriched with APA events. While tissue-specific genes typically have a low APA rate, brain-specific genes tend to evolve APA. We show enrichment of mRNA destabilizing motifs in alternative 3’UTR sequences, leading to substantial differences in mRNA stability between 3’UTR APA isoforms. Using conserved PASs, we reveal sequence motifs surrounding APA sites and a preference of adenosine at the cleavage site. Mutations of the U-rich motif around the PAS often accompany APA profile changes between species. Analysis of lncRNA PASs indicates a mechanism of PAS fixation involving evolution of A-rich motifs. Taken together, our results present a comprehensive view of PAS evolution in mammals, and a phylogenic understanding of APA functions.
2018-08-08 | GSE111134 | GEO
Project description:Sequencing of the 3’ end of poly(A)+ RNA identifies cleavage and polyadenylation sites (pAs) and measures transcript expression. We previously developed a method, 3’ region extraction and deep sequencing (3’READS), to address mispriming issues that often plague 3’ end sequencing. Here we report a new version, named 3’READS+, which has vastly improved accuracy and sensitivity. Using a special locked nucleic acid oligo to capture poly(A)+ RNA and to remove bulk of the poly(A) tail, 3’READS+ generates RNA fragments with an optimal number of terminal As that balance data quality and detection of genuine pAs. With improved RNA ligation steps for efficiency, the method shows much higher sensitivity (over two orders of magnitude) compared to the previous version. Using 3’READS+, we have uncovered a sizable fraction of previously overlooked pAs located next to or within a stretch of adenylate residues in human genes, and more accurately assessed the frequency of alternative cleavage and polyadenylation (APA) in HeLa cells (~50%). 3’READS+ will be a useful tool to accurately study APA and to analyze gene expression by 3’ end counting, especially when the amount of input total RNA is limited.
2016-08-14 | GSE84170 | GEO
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
2015-04-01 | E-GEOD-62001 | biostudies-arrayexpress
Project description:Alternative polyadenylation (APA) of mRNAs has emerged as an important mechanism for post-transcriptional gene regulation in higher eukaryotes. Although microarrays have recently been used to characterize APA globally, they have a number of serious limitations that prevents comprehensive and highly quantitative analysis. To better characterize APA and its regulation, we have developed a deep sequencing-based method called Poly(A) Site Sequencing (PAS-Seq) for quantitatively profiling RNA polyadenylation at the transcriptome level. PAS-Seq not only accurately and comprehensively identifies poly(A) junctions in mRNAs and noncoding RNAs, but also provides quantitative information on the relative abundance of polyadenylated RNAs. We first analyzed HeLa cell transcriptome using PAS-Seq to demonstrate that PAS-Seq not only accurately and comprehensively identifies poly(A) junctions, but also provide quantitative information on the relativel abundance of APA isoforms. Next we analyzed the mouse embryonic stem cells, neural stem/progenitor cells, and neurons by PAS-Seq to characterize the dynamic changes of mRNA polyadenylation during stem cell differentiation.
2011-02-26 | E-GEOD-25450 | biostudies-arrayexpress