Browse
Submit Data
Databases
API
Help

Dataset Information

20 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Exon Junction Complex Shapes the Transcriptome by Repressing Recursive Splicing.

ABSTRACT: Recursive splicing (RS) starts by defining an "RS-exon," which is then spliced to the preceding exon, thus creating a recursive 5' splice site (RS-5ss). Previous studies focused on cryptic RS-exons, and now we find that the exon junction complex (EJC) represses RS of hundreds of annotated, mainly constitutive RS-exons. The core EJC factors, and the peripheral factors PNN and RNPS1, maintain RS-exon inclusion by repressing spliceosomal assembly on RS-5ss. The EJC also blocks 5ss located near exon-exon junctions, thus repressing inclusion of cryptic microexons. The prevalence of annotated RS-exons is high in deuterostomes, while the cryptic RS-exons are more prevalent in Drosophila, where EJC appears less capable of repressing RS. Notably, incomplete repression of RS also contributes to physiological alternative splicing of several human RS-exons. Finally, haploinsufficiency of the EJC factor Magoh in mice is associated with skipping of RS-exons in the brain, with relevance to the microcephaly phenotype and human diseases.

SUBMITTER: Blazquez L

PROVIDER: S-EPMC6224609 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Exon junction complex shapes m6A epitranscriptome during splicing

Project description:N6-methyladenosine (m6A) is the most abundant post-transcriptional methylation of mature mRNA and plays a crucial regulatory role in various biological functions, involving development and cancer progression. m6A is deposited by methyltransferase complex composed of METTL3 and METTL14 cotranscriptionally, and removed by demethylase FTO or ALKBH5. m6A is highly enriched within the 3’ UTRs and in the vicinity of the stop codon of mature mRNA. However, the mechanism that causes this distribution pattern is still enigmatic. Here, we show that EJC packages mRNAs to shape mRNA m6A landscape. We first tested the possibility that demethylase removes m6A during spicing and found that ALKBH5 depletion had a minor effect on m6A levels. Thus, we ruled out the demethylation model. We then hypothesized that splicing factors inhibit the methylation process of internal exons, but not the 3’ UTR. Knockdown of EIF4A3, a core component of the exon junction complex, significantly increased m6A levels in mature mRNAs. The hypermethylated sites are enriched in short internal exons. Furthermore, EIF4A3 depletion upregulates METTL3 binding affinity to mRNA to deposit m6As. In conclusion, Our results demonstrate that EIF4A3 blocks METTL3 binding and methylating internal short exons of mRNA. These findings shed light on the fact that RNA packaging formed during splicing acts as a regulator that shapes mRNA modifications.

2022-12-06 | GSE207663 | GEO

Transcriptome-wide modulation of splicing by the exon junction complex.

Project description:BACKGROUND: The exon junction complex (EJC) is a dynamic multi-protein complex deposited onto nuclear spliced mRNAs upstream of exon-exon junctions. The four core proteins, eIF4A3, Magoh, Y14 and MLN51, are stably bound to mRNAs during their lifecycle, serving as a binding platform for other nuclear and cytoplasmic proteins. Recent evidence has shown that the EJC is involved in the splicing regulation of some specific events in both Drosophila and mammalian cells. RESULTS: Here, we show that knockdown of EJC core proteins causes widespread alternative splicing changes in mammalian cells. These splicing changes are specific to EJC core proteins, as knockdown of eIF4A3, Y14 and MLN51 shows similar splicing changes, and are different from knockdown of other splicing factors. The splicing changes can be rescued by a siRNA-resistant form of eIF4A3, indicating an involvement of EJC core proteins in regulating alternative splicing. Finally, we find that the splicing changes are linked with RNA polymerase II elongation rates. CONCLUSION: Taken together, this study reveals that the coupling between EJC proteins and splicing is broader than previously suspected, and that a possible link exists between mRNP assembly and splice site recognition.

| S-EPMC4268817 | biostudies-other

Transcriptome-wide modulation of splicing by the exon junction complex

Project description:We report that knockdown of EJC core proteins, eIF4A3, Y14, Magoh, causes a transcript-wide changes in alternative splicing, as well as some transcriptional changes. These changes are specific to EJC core proteins, and KD of UPF1 protein caused different sets of alterantive splicing changes. These changes are linked to the rate of transcription. Examination of 4 different knockdown, as well as GFP knockdown in HeLa cells, 2 replicates each condition.

2014-11-14 | E-GEOD-63091 | biostudies-arrayexpress

Transcriptome-wide modulation of splicing by the exon junction complex

2014-11-14 | GSE63091 | GEO

Promoter-proximal pausing mediated by the exon junction complex regulates splicing.

Project description:Promoter-proximal pausing of RNA polymerase II (Pol II) is a widespread transcriptional regulatory step across metazoans. Here we find that the nuclear exon junction complex (pre-EJC) is a critical and conserved regulator of this process. Depletion of pre-EJC subunits leads to a global decrease in Pol II pausing and to premature entry into elongation. This effect occurs, at least in part, via non-canonical recruitment of pre-EJC components at promoters. Failure to recruit the pre-EJC at promoters results in increased binding of the positive transcription elongation complex (P-TEFb) and in enhanced Pol II release. Notably, restoring pausing is sufficient to rescue exon skipping and the photoreceptor differentiation defect associated with depletion of pre-EJC components in vivo. We propose that the pre-EJC serves as an early transcriptional checkpoint to prevent premature entry into elongation, ensuring proper recruitment of RNA processing components that are necessary for exon definition.

| S-EPMC6355915 | biostudies-literature

The Exon Junction Complex and intron removal prevent re-splicing of mRNA.

Project description:Accurate splice site selection is critical for fruitful gene expression. Recently, the mammalian EJC was shown to repress competing, cryptic, splice sites (SS). However, the evolutionary generality of this remains unclear. Here, we demonstrate the Drosophila EJC suppresses hundreds of functional cryptic SS, even though most bear weak splicing motifs and are seemingly incompetent. Mechanistically, the EJC directly conceals cryptic splicing elements by virtue of its position-specific recruitment, preventing aberrant SS definition. Unexpectedly, we discover the EJC inhibits scores of regenerated 5' and 3' recursive SS on segments that have already undergone splicing, and that loss of EJC regulation triggers faulty resplicing of mRNA. An important corollary is that certain intronless cDNA constructs yield unanticipated, truncated transcripts generated by resplicing. We conclude the EJC has conserved roles to defend transcriptome fidelity by (1) repressing illegitimate splice sites on pre-mRNAs, and (2) preventing inadvertent activation of such sites on spliced segments.

| S-EPMC8184009 | biostudies-literature

TDP-43 regulates global translational yield by splicing of exon junction complex component SKAR.

Project description:TDP-43 is linked to neurodegenerative diseases including frontotemporal dementia and amyotrophic lateral sclerosis. Mostly localized in the nucleus, TDP-43 acts in conjunction with other ribonucleoproteins as a splicing co-factor. Several RNA targets of TDP-43 have been identified so far, but its role(s) in pathogenesis remains unclear. Using Affymetrix exon arrays, we have screened for the first time for splicing events upon TDP-43 knockdown. We found alternative splicing of the ribosomal S6 kinase 1 (S6K1) Aly/REF-like target (SKAR) upon TDP-43 knockdown in non-neuronal and neuronal cell lines. Alternative SKAR splicing depended on the first RNA recognition motif (RRM1) of TDP-43 and on 5'-GA-3' and 5'-UG-3' repeats within the SKAR pre-mRNA. SKAR is a component of the exon junction complex, which recruits S6K1, thereby facilitating the pioneer round of translation and promoting cell growth. Indeed, we found that expression of the alternatively spliced SKAR enhanced S6K1-dependent signaling pathways and the translational yield of a splice-dependent reporter. Consistent with this, TDP-43 knockdown also increased translational yield and significantly increased cell size. This indicates a novel mechanism of deregulated translational control upon TDP-43 deficiency, which might contribute to pathogenesis of the protein aggregation diseases frontotemporal dementia and amyotrophic lateral sclerosis.

| S-EPMC3315294 | biostudies-literature

Promoter-proximal pausing mediated by the exon junction complex regulates splicing

2019-01-22 | GSE92389 | GEO

Proteins associated with the exon junction complex also control the alternative splicing of apoptotic regulators.

Project description:Several apoptotic regulators, including Bcl-x, are alternatively spliced to produce isoforms with opposite functions. We have used an RNA interference strategy to map the regulatory landscape controlling the expression of the Bcl-x splice variants in human cells. Depleting proteins known as core (Y14 and eIF4A3) or auxiliary (RNPS1, Acinus, and SAP18) components of the exon junction complex (EJC) improved the production of the proapoptotic Bcl-x(S) splice variant. This effect was not seen when we depleted EJC proteins that typically participate in mRNA export (UAP56, Aly/Ref, and TAP) or that associate with the EJC to enforce nonsense-mediated RNA decay (MNL51, Upf1, Upf2, and Upf3b). Core and auxiliary EJC components modulated Bcl-x splicing through different cis-acting elements, further suggesting that this activity is distinct from the established EJC function. In support of a direct role in splicing control, recombinant eIF4A3, Y14, and Magoh proteins associated preferentially with the endogenous Bcl-x pre-mRNA, interacted with a model Bcl-x pre-mRNA in early splicing complexes, and specifically shifted Bcl-x alternative splicing in nuclear extracts. Finally, the depletion of Y14, eIF4A3, RNPS1, SAP18, and Acinus also encouraged the production of other proapoptotic splice variants, suggesting that EJC-associated components are important regulators of apoptosis acting at the alternative splicing level.

| S-EPMC3295189 | biostudies-literature

Exon junction complex proteins bind nascent transcripts independently of pre-mRNA splicing in Drosophila melanogaster.

Project description:Although it is currently understood that the exon junction complex (EJC) is recruited on spliced mRNA by a specific interaction between its central protein, eIF4AIII, and splicing factor CWC22, we found that eIF4AIII and the other EJC core proteins Y14 and MAGO bind the nascent transcripts of not only intron-containing but also intronless genes on Drosophila polytene chromosomes. Additionally, Y14 ChIP-seq demonstrates that association with transcribed genes is also splicing-independent in Drosophila S2 cells. The association of the EJC proteins with nascent transcripts does not require CWC22 and that of Y14 and MAGO is independent of eIF4AIII. We also show that eIF4AIII associates with both polysomal and monosomal RNA in S2 cell extracts, whereas Y14 and MAGO fractionate separately. Cumulatively, our data indicate a global role of eIF4AIII in gene expression, which would be independent of Y14 and MAGO, splicing, and of the EJC, as currently understood.

| S-EPMC5158136 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data