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Molecular Cell Sep 2022Alternative polyadenylation (APA) enhances gene regulatory potential by increasing the diversity of mRNA transcripts. 3' UTR shortening through APA correlates with...
Alternative polyadenylation (APA) enhances gene regulatory potential by increasing the diversity of mRNA transcripts. 3' UTR shortening through APA correlates with enhanced cellular proliferation and is a widespread phenomenon in tumor cells. Here, we show that the ubiquitously expressed transcription factor Sp1 binds RNA in vivo and is a common repressor of distal poly(A) site usage. RNA sequencing identified 2,344 genes (36% of the total mapped mRNA transcripts) with lengthened 3' UTRs upon Sp1 depletion. Sp1 preferentially binds the 3' UTRs of such lengthened transcripts and inhibits cleavage at distal sites by interacting with the subunits of the core cleavage and polyadenylation (CPA) machinery. The 3' UTR lengths of Sp1 target genes in breast cancer patient RNA-seq data correlate with Sp1 expression levels, implicating Sp1-mediated APA regulation in modulating tumorigenic properties. Taken together, our findings provide insights into the mechanism for dynamic APA regulation by unraveling a previously unknown function of the DNA-binding transcription factor Sp1.
Topics: 3' Untranslated Regions; Humans; Poly A; Polyadenylation; RNA, Messenger; Sp1 Transcription Factor; Zinc
PubMed: 35914531
DOI: 10.1016/j.molcel.2022.06.031 -
Wiley Interdisciplinary Reviews. RNA 2011Although the first poly(A) polymerase (PAP) was discovered in Escherichia coli in 1962, the study of polyadenylation in bacteria was largely ignored for the next 30... (Review)
Review
Although the first poly(A) polymerase (PAP) was discovered in Escherichia coli in 1962, the study of polyadenylation in bacteria was largely ignored for the next 30 years. However, with the identification of the structural gene for E. coli PAP I in 1992, it became possible to analyze polyadenylation using both biochemical and genetic approaches. Subsequently, it has been shown that polyadenylation plays a multifunctional role in prokaryotic RNA metabolism. Although the bulk of our current understanding of prokaryotic polyadenylation comes from studies on E. coli, recent limited experiments with Cyanobacteria, organelles, and Archaea have widened our view on the diversity, complexity, and universality of the polyadenylation process. For example, the identification of polynucleotide phosphorylase (PNPase), a reversible phosphorolytic enzyme that is highly conserved in bacteria, as an additional PAP in E. coli caught everyone by surprise. In fact, PNPase has now been shown to be the source of post-transcriptional RNA modifications in a wide range of cells of prokaryotic origin including those that lack a eubacterial PAP homolog. Accordingly, the past few years have witnessed increased interest in the mechanism and role of post-transcriptional modifications in all species of prokaryotic origin. However, the fact that many of the poly(A) tails are very short and unstable as well as the presence of polynucleotide tails has posed significant technical challenges to the scientific community trying to unravel the mystery of polyadenylation in prokaryotes. This review discusses the current state of knowledge regarding polyadenylation and its functions in bacteria, organelles, and Archaea.
Topics: Animals; Archaea; Bacteria; Base Sequence; Humans; Models, Biological; Molecular Sequence Data; Organelles; Polyadenylation; Quality Control; RNA Stability
PubMed: 21344039
DOI: 10.1002/wrna.51 -
Philosophical Transactions of the Royal... Nov 2018Post-transcriptional addition of poly(A) tails to the 3' end of RNA is one of the fundamental events controlling the functionality and fate of RNA in all kingdoms of... (Review)
Review
Post-transcriptional addition of poly(A) tails to the 3' end of RNA is one of the fundamental events controlling the functionality and fate of RNA in all kingdoms of life. Although an enzyme with poly(A)-adding activity was discovered in more than 50 years ago, its existence and role in prokaryotic RNA metabolism were neglected for many years. As a result, it was not until 1992 that poly(A) polymerase I was purified to homogeneity and its gene was finally identified. Further work revealed that, similar to its role in surveillance of aberrant nuclear RNAs of eukaryotes, the addition of poly(A) tails often destabilizes prokaryotic RNAs and their decay intermediates, thus facilitating RNA turnover. Moreover, numerous studies carried out over the last three decades have shown that polyadenylation greatly contributes to the control of prokaryotic gene expression by affecting the steady-state level of diverse protein-coding and non-coding transcripts including antisense RNAs involved in plasmid copy number control, expression of toxin-antitoxin systems and bacteriophage development. Here, we review the main findings related to the discovery of polyadenylation in prokaryotes, isolation, and characterization and regulation of bacterial poly(A)-adding activities, and discuss the impact of polyadenylation on prokaryotic mRNA metabolism and gene expression.This article is part of the theme issue '5' and 3' modifications controlling RNA degradation'.
Topics: Bacteria; Poly A; Polyadenylation; Prokaryotic Cells; RNA
PubMed: 30397102
DOI: 10.1098/rstb.2018.0166 -
Cell Reports Apr 2023Telomeric repeat-containing RNA (TERRA) is a long non-coding RNA transcribed from telomeres that plays key roles in telomere maintenance. A fraction of TERRA is...
Telomeric repeat-containing RNA (TERRA) is a long non-coding RNA transcribed from telomeres that plays key roles in telomere maintenance. A fraction of TERRA is polyadenylated, and the presence of the poly(A) tail influences TERRA localization and stability. However, the mechanisms of TERRA biogenesis remain mostly elusive. Here, we show that the stability of TERRA transcripts is regulated by the RNA-binding protein associated with lethal yellow mutation (RALY). RALY depletion results in lower TERRA levels, impaired localization of TERRA at telomeres, and ultimately telomere damage. Importantly, we show that TERRA polyadenylation is telomere specific and that RALY preferentially stabilizes non-polyadenylated TERRA transcripts. Finally, we report that TERRA interacts with the poly(A)-binding protein nuclear 1 (PABPN1). Altogether, our results indicate that TERRA stability is regulated by the interplay between RALY and PABPN1, defined by the TERRA polyadenylation state. Our findings also suggest that different telomeres may trigger distinct TERRA-mediated responses.
Topics: RNA, Long Noncoding; Polyadenylation; RNA, Messenger; Telomere
PubMed: 37060569
DOI: 10.1016/j.celrep.2023.112406 -
Nucleus (Austin, Tex.) 2014Polyadenylation is the RNA processing step that completes the maturation of nearly all eukaryotic mRNAs. It is a two-step nuclear process that involves an... (Review)
Review
Polyadenylation is the RNA processing step that completes the maturation of nearly all eukaryotic mRNAs. It is a two-step nuclear process that involves an endonucleolytic cleavage of the pre-mRNA at the 3'-end and the polymerization of a polyadenosine (polyA) tail, which is fundamental for mRNA stability, nuclear export and efficient translation during development. The core molecular machinery responsible for the definition of a polyA site includes several recognition, cleavage and polyadenylation factors that identify and act on a given polyA signal present in a pre-mRNA, usually an AAUAAA hexamer or similar sequence. This mechanism is tightly regulated by other cis-acting elements and trans-acting factors, and its misregulation can cause inefficient gene expression and may ultimately lead to disease. The majority of genes generate multiple mRNAs as a result of alternative polyadenylation in the 3'-untranslated region. The variable lengths of the 3' untranslated regions created by alternative polyadenylation are a recognizable target for differential regulation and clearly affect the fate of the transcript, ultimately modulating the expression of the gene. Over the past few years, several studies have highlighted the importance of polyadenylation and alternative polyadenylation in gene expression and their impact in a variety of physiological conditions, as well as in several illnesses. Abnormalities in the 3'-end processing mechanisms thus represent a common feature among many oncological, immunological, neurological and hematological disorders, but slight imbalances can lead to the natural establishment of a specific cellular state. This review addresses the key steps of polyadenylation and alternative polyadenylation in different cellular conditions and diseases focusing on the molecular effectors that ensure a faultless pre-mRNA 3' end formation.
Topics: 3' Untranslated Regions; Gene Expression Regulation, Developmental; Genetic Diseases, Inborn; Humans; Poly A; Polyadenylation; RNA Stability; RNA, Messenger
PubMed: 25484187
DOI: 10.4161/nucl.36360 -
Molekuliarnaia Biologiia 2017Polyadenylation is the non-template addition of adenosine nucleotides at the 3'-end of RNA, which occurs after transcription and generates a poly(A) tail up to 250-300... (Review)
Review
Polyadenylation is the non-template addition of adenosine nucleotides at the 3'-end of RNA, which occurs after transcription and generates a poly(A) tail up to 250-300 nucleotides long. In the first section of our review, we consider the classical process of mRNA 3'-terminus formation, which involves the cleavage of the transcript synthesized by RNA polymerase II and the associated poly(A) tail synthesis by canonical polyadenylate polymerase. Nucleotide sequences needed for mRNA cleavage and poly(A) tail synthesis, in particular the AAUAAA polyadenylation signal, as well as numerous proteins and their complexes involved in mRNA cleavage and polyadenylation, is described in detail. The significance of the poly(A) tail for prolonging mRNA lifetime and stimulating their translation is discussed. Data presented in the second section demonstrate that RNA transcribed by RNA polymerase III from certain SINEs (Short Interspersed Elements) can undergo AAUAAA-dependent polyadenylation. The structural and functional features of RNA polymerase III determine the unusual character of polyadenylation of RNAs synthesized by this enzyme. The history of recent developments in this area of study have been described in greater detail, in particular the discovery of AAUAAA-dependent polyadenylation of RNA synthesized by RNA polymerase III, which has not been discussed previously. Data on AAUAAA-independent polyadenylation catalyzed by noncanonical TRAMP poly(A)-polymerases (Trf4 and Trf5) have been presented in the third section. These enzymes promote rapid degradation of RNAs by adding a short poly(A) tail to them. This mechanism enables the recognition, poly(A)-marking, and elimination of incorrectly folded noncoding transcripts (e.g. ribosomal and transfer RNAs).
Topics: Animals; Humans; Poly A; Polyadenylation; RNA, Messenger
PubMed: 28537233
DOI: 10.7868/S0026898417010189 -
Trends in Cell Biology Mar 2019Poly(A) tails are non-templated additions of adenosines at the 3' ends of most eukaryotic mRNAs. In the nucleus, these RNAs are co-transcriptionally cleaved at a poly(A)... (Review)
Review
Poly(A) tails are non-templated additions of adenosines at the 3' ends of most eukaryotic mRNAs. In the nucleus, these RNAs are co-transcriptionally cleaved at a poly(A) site and then polyadenylated before being exported to the cytoplasm. In the cytoplasm, poly(A) tails play pivotal roles in the translation and stability of the mRNA. One challenge in studying poly(A) tails is that they are difficult to sequence and accurately measure. However, recent advances in sequencing technology, computational algorithms, and other assays have enabled a more detailed look at poly(A) tail length genome-wide throughout many developmental stages and organisms. With the help of these advances, our understanding of poly(A) tail length has evolved over the past 5 years with the recognition that highly expressed genes can have short poly(A) tails and the elucidation of the seemingly contradictory roles for poly(A)-binding protein (PABP) in facilitating both protection and deadenylation.
Topics: Algorithms; Animals; Cell Nucleus; Computational Biology; Cytoplasm; Humans; Poly A; RNA, Messenger; Sequence Analysis, RNA
PubMed: 30503240
DOI: 10.1016/j.tcb.2018.11.002 -
ELife Nov 2022Alternative polyadenylation yields many mRNA isoforms whose 3' termini occur disproportionately in clusters within 3' untranslated regions. Previously, we showed that...
Alternative polyadenylation yields many mRNA isoforms whose 3' termini occur disproportionately in clusters within 3' untranslated regions. Previously, we showed that profiles of poly(A) site usage are regulated by the rate of transcriptional elongation by RNA polymerase (Pol) II (Geisberg et al., 2020). Pol II derivatives with slow elongation rates confer an upstream-shifted poly(A) profile, whereas fast Pol II strains confer a downstream-shifted poly(A) profile. Within yeast isoform clusters, these shifts occur steadily from one isoform to the next across nucleotide distances. In contrast, the shift between clusters - from the last isoform of one cluster to the first isoform of the next - is much less pronounced, even over large distances. GC content in a region 13-30 nt downstream from isoform clusters correlates with their sensitivity to Pol II elongation rate. In human cells, the upstream shift caused by a slow Pol II mutant also occurs continuously at single nucleotide resolution within clusters but not between them. Pol II occupancy increases just downstream of poly(A) sites, suggesting a linkage between reduced elongation rate and cluster formation. These observations suggest that (1) Pol II elongation speed affects the nucleotide-level dwell time allowing polyadenylation to occur, (2) poly(A) site clusters are linked to the local elongation rate, and hence do not arise simply by intrinsically imprecise cleavage and polyadenylation of the RNA substrate, (3) DNA sequence elements can affect Pol II elongation and poly(A) profiles, and (4) the cleavage/polyadenylation and Pol II elongation complexes are spatially, and perhaps physically, coupled so that polyadenylation occurs rapidly upon emergence of the nascent RNA from the Pol II elongation complex.
Topics: Humans; Polyadenylation; Nucleotides; RNA Polymerase II; Poly A; Saccharomyces cerevisiae; 3' Untranslated Regions; Transcription, Genetic
PubMed: 36421680
DOI: 10.7554/eLife.83153 -
Proceedings of the National Academy of... Dec 2022Alternative polyadenylation (APA) plays an important role in posttranscriptional gene regulation such as transcript stability and translation efficiency. However, our...
Alternative polyadenylation (APA) plays an important role in posttranscriptional gene regulation such as transcript stability and translation efficiency. However, our knowledge about APA dynamics at the single-cell level is largely unexplored. Here, we developed single-cell polyadenylation sequencing, a strand-specific approach for sequencing the 3' end of transcripts, to investigate the landscape of APA at the single-cell level. By analyzing several cell lines, we found many genes using multiple polyA sites in bulk data are prone to use only one polyA site in each single cell. Interestingly, cell cycle genes were significantly enriched in genes with high variation in polyA site usages. Furthermore, the 414 genes showing a polyA site usage switch after cell synchronization enriched cell cycle genes, while the differentially expressed genes after cell synchronization did not enrich cell cycle genes. We further identified 812 genes showing polyA site usage changes between neighboring cell cycles, which were grouped into six clusters, with cell phase-specific functional categories enriched in each cluster. Deletion of one polyA site in and results in slower and faster cell cycle progression, respectively, supporting polyA site usage switch played an important role in cell cycle. These results indicate that APA is an important layer for cell cycle regulation.
Topics: Polyadenylation; Poly A; Genes, cdc; Cell Cycle; Cell Division
PubMed: 36454750
DOI: 10.1073/pnas.2113504119 -
Transcription 2022The processing of the proximal and distal poly(A) sites in alternative polyadenylation (APA) has long been thought to independently occur on pre-mRNAs during... (Review)
Review
The processing of the proximal and distal poly(A) sites in alternative polyadenylation (APA) has long been thought to independently occur on pre-mRNAs during transcription. However, a recent study by our groups demonstrated that the proximal sites for many genes could be activated sequentially following the distal ones, suggesting a multi-cleavage-same-transcript mode beyond the canonical one-cleavage-per-transcript view. Here, we review the established mechanisms for APA regulation and then discuss the additional insights into APA regulation from the perspective of sequential polyadenylation, resulting in a unified leverage model for understanding the mechanisms of regulated APA.
Topics: Polyadenylation; Gene Expression Regulation
PubMed: 36004392
DOI: 10.1080/21541264.2022.2114776