Widespread transcriptional readthrough caused by Nab2 depletion leads to chimeric transcripts with retained introns
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PROVIDER: PRJNA656824 | ENA |
REPOSITORIES: ENA
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Project description:Nascent RNA sequencing has recently revealed that pre-mRNA splicing can occur shortly after the intron emerges from RNA polymerase II (Pol II). Differences in co-transcriptional splicing profiles suggest regulation by cis- and/or trans-acting factors. Here we used Single Molecule Intron Tracking (SMIT) in budding yeast to identify a cohort of regulators by machine learning. One candidate, Nab2, displayed reduced co-transcriptional splicing of some pre-mRNAs when depleted. Unexpectedly, these splicing defects were attributable to readthrough transcription, which was revealed by long read sequencing of nascent RNA; individual readthrough transcripts induced by Nab2 depletion sometimes spanned multiple genes. Thus, Nab2 regulation of splicing was indirect. Moreover, unspliced transcripts displayed downstream readthrough in both control and Nab2-depleted cells, highlighting the coupling between splicing and 3′ end formation. We conclude that Nab2 is required for proper 3′ end processing, which ensures both transcription termination as well as proper splicing of downstream genes.
2020-10-27 | GSE156133 | GEO
Project description: Not available
| S-EPMC7774305 | biostudies-literature
Project description:Intron retention (IR) is an alternative splicing event where mRNAs containing unspliced introns are exported to the cytoplasm and then either translated, giving rise to new protein isoforms, or degraded via the nonsense-mediated decay pathway. However, unspliced introns are also seen in nuclear RNA. Some of these are spliced at a low rate but do eventually become fully spliced and their respective mRNAs exported, while others stay retained and are recognized by nuclear decay machineries. IR has been shown to be regulated during granulocyte and neuronal differentiation and in some cancers, and a subset of the nuclear retained introns, called detained introns, have been implicated in growth control pathways. Despite many findings on IR and its biological significance, it is still not clear whether an incompletely spliced intron observed is a true retained intron that is exported as an mRNA or is a product of slow splicing that remains in the nucleus. A better understanding is needed of the molecular events that reduce intron excision rate and determine the release of an RNA for export. We have found that some genes in mouse embryonic stem cells (mESCs) produce RNAs that are highly associated with the high molecular-weight nuclear pellet (chromatin), rather than the soluble nucleoplasm or cytoplasm. This chromatin-associated RNA is polyadenylated, usually contains one or more incompletely spliced introns, and is often extensively bound by polypyrimidine tract-binding protein 1 (PTBP1). We hypothesize that PTBP1 inhibits splicing of these introns, and this causes sequestration of the transcript on chromatin. We are studying the role of PTBP1 in inhibiting intron excision and anchoring RNAs in the nuclear and chromatin compartments of mESCs.
2020-11-18 | GSE159993 | GEO
Project description:Genome-wide analysis of PTBP1-regulated retained introns in mESCs
| PRJNA671499 | ENA
Project description:The nucleus is highly compartmentalized through the formation of distinct classes of membraneless domains, yet the composition and function of many of these structures is not well understood. Using APEX2-mediated proximity labelling and RNA sequencing, we surveyed transcripts associated with nuclear speckles, several additional domains, and the lamina. Remarkably, speckles and lamina are associated with distinct classes of retained introns enriched in genes that function in RNA processing, translation, and the cell cycle. In contrast to the lamina-proximal introns, retained introns associated with speckles are relatively short, GC-rich, and enriched for functional sites of RNA binding proteins that are concentrated in these domains. They are also highly differentially regulated across diverse cellular contexts, including the cell cycle. Our study thus provides a resource of nuclear domain-associated transcripts and further reveals speckles and lamina as hubs of distinct populations of retained introns linked to gene regulation and cell cycle progression.
2022-02-18 | GSE176439 | GEO
Project description:The Drosophila polyadenosine RNA binding protein Nab2, which is orthologous to a human protein lost in a form of inherited intellectual disability, controls axon projection, locomotion, and memory. Here we define an unexpectedly specific role for Nab2 in regulating splicing of ~150 exons/introns in the head transcriptome and link the most prominent of these, female retention of a male-specific exon in the sex determination factor Sex-lethal (Sxl), to a role in m6A-dependent mRNA splicing. Genetic evidence indicates that aberrant Sxl splicing underlies multiple phenotypes in Nab2 mutant females. At a molecular level, Nab2 associates with Sxl pre-mRNA and ensures proper female-specific splicing by preventing m6A hypermethylation by Mettl3 methyltransferase. Consistent with these results, reducing Mettl3 expression rescues developmental, behavioral and neuroanatomical phenotypes in Nab2 mutants. Overall these data identify Nab2 as a required regulator of m6A-regulated Sxl splicing and imply a broader link between Nab2 and Mettl3-regulated brain RNAs.
2020-12-02 | GSE162531 | GEO
Project description:Removal of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation. v6.5 mouse embryonic stem cells were untreated, treated with the Clk kinase inhibitor KH-CB19, or treated with DMSO as a negative control. Untreated cells were harvested and a single replicate was sequenced using a custom, ligation-based, stranded library preparation protocol. Treated cells were harvested at time 0 and at 2 hours post-treatment, and poly(A)-selected RNA-seq libraries were made from biological duplicates for each treatment/time, barcoded, and sequenced by strand-specific, paired-end sequencing using the Illumina TruSeq kit.
2015-01-15 | E-GEOD-57231 | biostudies-arrayexpress
Project description:Gene expression in eukaryotes is an essential process that includes transcription, pre-RNA processing and RNA export. All these steps are coupled and normally, any failure in one step affects the other steps and could cause nuclear mRNA retention. One important player in this interface is the poly(A)-RNA binding protein Nab2, which regulates the poly(A)-tail length of mRNAs protecting their 3’-ends from a second round of polyadenylation and facilitating their nucleo-cytoplasmic export. Interestingly, here we show that Nab2 has additional roles in mRNA transcription elongation, tRNA metabolism and rRNA export. We use Genome-wide analysis of expression of a conditional degron nab2 mutant that allows the depletion of the protein in 15 minutes, to demosntrate that the role of Nab2 in RNAPII transcription and RNAPIII metabolism is not the result of a secondary effect. Our results identify primary targets of nab2 revealing novel functions for Nab2 in transcription and metabolism of most types of RNAs, not only poly(A) mRNAs, indicating that Nab2 function is more ubiquitous than previously anticipated, being a central player in the general and coordinated control of gene expression from transcription elongation to translation initiation.
2011-12-01 | GSE19302 | GEO
Project description:Removal of introns by pre-mRNA splicing is a critical and in some cases rate-limiting step in mammalian gene expression. Deep sequencing of mouse embryonic stem cell RNA revealed many specific internal introns that are significantly more abundant than the other introns within poly(A) selected transcripts; we classify these as “detained” introns (DIs). We identified thousands of DIs flanking both constitutive and alternatively spliced exons in human and mouse cell lines. Drug inhibition of Clk SR-protein kinase activity triggered rapid splicing changes in a specific set of DIs, about half of which showed increased splicing and half increased intron detention, altering the transcript pool of over 300 genes. These data suggest a widespread mechanism by which a nuclear detained pool of mostly processed pre-mRNAs can be rapidly mobilized in response to stress or homeostatic autoregulation.
2015-01-15 | GSE57231 | GEO
Project description:Gene expression in eukaryotes is an essential process that includes transcription, pre-RNA processing and RNA export. All these steps are coupled and normally, any failure in one step affects the other steps and could cause nuclear mRNA retention. One important player in this interface is the poly(A)-RNA binding protein Nab2, which regulates the poly(A)-tail length of mRNAs protecting their 3M-bM-^@M-^Y-ends from a second round of polyadenylation and facilitating their nucleo-cytoplasmic export. Interestingly, here we show that Nab2 has additional roles in mRNA transcription elongation, tRNA metabolism and rRNA export. We use Genome-wide analysis of expression of nab2-1 mutant to demosntrate that the role of Nab2 in RNAPII transcription and RNAPIII metabolism is not the result of a secondary effect. Our results identify primary targets of nab2 revealing novel functions for Nab2 in transcription and metabolism of most types of RNAs, not only poly(A) mRNAs, indicating that Nab2 function is more ubiquitous than previously anticipated, being a central player in the general and coordinated control of gene expression from transcription elongation to translation initiation. Three repeats of the wild type and nab2-1 mutant
2011-12-01 | E-GEOD-26303 | biostudies-arrayexpress