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PubMed2024

Design and evaluation of antisense sequence length for modified mouse U7 small nuclear RNA to induce efficient pre-messenger RNA splicing modulation in vitro.

Pre-messenger RNA (pre-mRNA) splicing modulation is an attractive approach for investigating the mechanisms of genetic disorders caused by mis-splicing. Previous reports have indicated that a modified U7 small nuclear RNA (U7 snRNA) is a prospective tool for modulating splicing both in vitro and in vivo. To date, very few studies have investigated the role of antisense sequence length in modified U7 snRNA. In this study, we designed a series of antisense sequences with various lengths and evaluated their efficiency in inducing splicing modulation. To express modified U7 snRNAs, we constructed a series of plasmid DNA sequences which codes cytomegalovirus (CMV) enhancer, human U1 promoter, and modified mouse U7 snRNAs with antisense sequences of different lengths. We evaluated in vitro splicing modulation efficiency using a luciferase reporter system for simple and precise evaluation as well as reverse transcription-polymerase chain reaction to monitor splicing patterns. Our in vitro assay findings suggest that antisense sequences of modified mouse U7 snRNAs have an optimal length for efficient splicing modulation, which depends on the target exon. In addition, antisense sequences that were either too long or too short decreased splicing modulation efficiency. To confirm reproducibility, we performed an in vitro assay using two target genes, mouse Fas and mouse Dmd. Together, our data suggests that the antisense sequence length should be optimized for modified mouse U7 snRNAs to induce efficient splicing modulation.

RNA, Small Nuclear↗

PubMed2025

Co-transcriptional splicing is delayed in the highly expressed thyroglobulin gene.

Transcription of the majority of eukaryotic genes is accompanied by splicing. The timing of splicing varies significantly between introns, transcripts, genes and species. Although quick co-transcriptional intron removal has been demonstrated for many mammalian genes, most splicing events do not occur immediately after intron synthesis. In this study, we utilized the highly expressed Tg gene, which forms exceptionally long transcription loops, providing a convenient model for studying splicing dynamics using advanced light microscopy. Using single-cell oligopainting, we observed a splicing delay occurring several tens of kilobases downstream of a transcribed intron, a finding supported by standard cell population analyses. We speculate that this phenomenon is due to the abnormally high transcriptional rate of the Tg gene, which might lead to a localized deficiency in splicing factors and, consequently, delayed spliceosome assembly on thousands of nascent transcripts decorating the gene. Additionally, we found that, in contrast to what is seen for short introns (<10 kb), the long Tg intron (>50 kb) is spliced promptly, providing further support for the idea that intron length might modulate splicing speed.

RNA Splicing↗

PubMed2026

Bioinformatic analysis reveals the potential association of ESRP1 with the splicing of cytoskeleton-associated genes in doxorubicin-resistant MCF7 breast cancer cells.

BACKGROUND: Breast cancer remains one of the most prevalent malignancies among women, with doxorubicin resistance posing a significant challenge that undermines treatment success and survival outcomes. Aberrant alternative splicing (AS), driven by dysregulation or mutations in splicing factors (SFs), is implicated in cancer initiation, progression, and drug resistance. This study aims to investigate the association of the epithelial cell-specific splicing factor ESRP1 with doxorubicin resistance in breast cancer, focusing on how ESRP1 deficiency correlates with AS changes that promote chemoresistance. METHODS: We analyzed RNA-sequencing (RNA-seq) data from doxorubicin-resistant (MCF7-DR) and parental (MCF7) breast cancer cell lines to identify enhanced alternative splicing events (ASEs) and changes in ESRP1 expression; we further leveraged The Cancer Genome Atlas (TCGA)-BRCA cohort to construct an SF-RASE correlation network for screening core SFs (including ESRP1). An integrative analysis combining crosslinking immunoprecipitation (CLIP-seq) data and The Cancer Genome Atlas (TCGA) database was performed to validate ESRP1 binding targets and assess the association between ESRP1-related splicing and cytoskeleton organization. RESULTS: We observed extensive AS changes and significantly downregulated ESRP1 expression in MCF7-DR cells. Integrative analysis identified 61 high-confidence ASEs that correlate with ESRP1 expression. Further bioinformatic integration suggests that ESRP1 expression is associated with the splicing patterns of SPTBN1, MAP2K7, FGFR3, and CYB561A3-four genes involved in cytoskeleton organization-though direct experimental verification to confirm a causal regulatory relationship between ESRP1 and the splicing of these genes is still pending. CONCLUSIONS: Our findings suggest that ESRP1 expression is closely associated with doxorubicin resistance in breast cancer cells, with concomitant alterations in key ASEs linked to cytoskeletal remodeling that correlate with ESRP1. Exploring the ESRP1-related splicing network may offer new strategies to overcome chemoresistance and improve patient outcomes. However, the small cell line sample size (n = 2 per group) constrains the robustness of ASE and SF-ASE correlation findings, and these results should be interpreted with caution and require further validation with larger sample cohorts.

Alternative splicing↗

PubMed2026

Promoter identity shapes splicing outcomes and fidelity.

Gene expression is a complex process subject to regulation at multiple functionally interconnected levels. One prominent example is the crosstalk between transcription and splicing regulation. Past work has shown that transcription can influence splicing in multiple ways, but a systematic investigation of this complex interplay is lacking. Here we employ massively parallel reporter assays of large combinatorial promoter-splice site libraries to dissect how promoter identity and transcription dynamics affect alternative splicing in human cells. We find that promoter identity, rather than expression level, exerts strong and highly context-specific effects on cassette exon inclusion, exceeding the effect of pharmacological inhibitors of transcription initiation or elongation. Groups of exons display coordinated promoter-dependent splicing behavior, and we identified predictive sequence and structural features underlying this sensitivity. Promoter and gene architecture also shape isoform diversity by modulating cryptic splice site usage. These findings present promoters as central regulators of splicing outcomes and fidelity.

Humans↗

PubMed2026

RNA splicing and cardiovascular disease: a guide for cardiologists.

Alternative splicing (AS) is a fundamental RNA processing mechanism, which generates different RNA transcripts and consequently different protein isoforms from a single gene. This increases the diversity of proteins within an organism and can fine-tune biological processes. This review examines how cardiac-enriched RNA-binding proteins establish heart-specific splicing programs governing aspects of cardiac development, function, and disease. Developmentally, coordinated sarcomeric isoform switches underpin the foetal-to-adult transition and further isoform rewiring in ion channel and kinase genes determine electrophysiology and excitation-contraction coupling. AS contributes to the pathogenesis of several cardiomyopathies and emerging datasets suggest that pathological hypertrophy engages distinct splicing signatures compared with physiological hypertrophy. This review summarizes diagnostic and prognostic opportunities arising from bulk, long-read, and single-cell/nucleus transcriptomics, which resolve cell type-specific isoforms and disease-associated switches. Circulating RNA biomarkers (including splice ratios and circularRNAs) may signify myocardial remodelling and arrhythmic risk. Integrative approaches that link AS with proteomics and genomics improve variant interpretation, reveal previously unannotated protein isoforms, and enable tracking of disease progression and therapy response. Finally, an outline of therapeutic strategies to modulate AS in cardiovascular disease (CVD), including antisense oligonucleotides, small molecules, and genome-editing modalities (CRISPR, base, and prime editing), is provided. The major challenges that remain before splice-targeting therapeutics can be targeted to treat cardiovascular disease are highlighted. Lessons from neuromuscular indications establish clinical feasibility of splicing correction and motivate translation to cardiology. Together, mechanistic insight, biomarker development, and therapeutic innovation position RNA splicing as a tractable axis for precision cardiovascular medicine.

Humans↗

PubMed2026

The structured mRNA element 45ABC mediates auto- and cross-regulation of RBP45 genes via alternative splicing.

Alternative splicing (AS) is a common gene regulatory mechanism involving distinct interactions between trans-acting factors and cis-regulatory elements on the precursor messenger RNA (pre-mRNA). In this study, we have functionally characterized the structured motif 45ABC, which is located in the pre-mRNAs of RNA-binding protein (RBP) 45 genes in many plant species. Our data revealed that this element mediates a negative auto- and cross-regulatory feedback loop via AS of the three 45ABC-containing RBP45 genes in Arabidopsis thaliana. We identified a G-rich stretch within the first stem as a potential RBP45 binding site and observed increased RBP45-dependent AS upon structural weakening of this pairing element. The second stem includes the alternative 5' splice site being activated in the presence of RBP45. Based on the known interaction between RBP45 homologs and U1 snRNP components required for 5' splice site recognition, we propose that RBP45 recruitment to stem I of 45ABC may induce usage of the alternative 5' splice site in stem II. The resulting splicing variant is unproductive, thereby diminishing RBP45 expression. Analysing the splicing-regulatory impact of the three At-RBP45 genes in auto- and cross-regulation and a transcriptome-wide manner revealed unequal genetic redundancy with a major role of RBP45B. Furthermore, phenotypical analysis of single- and higher-order rbp45 mutants pointed at these genes' functions in controlling primary root growth and flowering time. Taken together, we demonstrated that both sequence and structural features of 45ABC are critical for proper splicing control, balancing RBP45 expression and functions in plants via a conserved mRNA motif.

Alternative Splicing↗

PubMed2025

Pervasive noise in human splice site selection.

RNA splicing has historically been thought to be highly efficient and accurate, with little opportunity for deviation from regulated alternative splicing decisions. This dogma has been challenged by recent observations that suggest that biological noise may contribute substantially to transcriptome diversity. However, quantitative understanding of stochastic variations in splicing is challenging because these transcripts are likely subject to rapid degradation. Here, we use ultra-deep sequencing across RNA compartments to track splicing intermediates in human cells and see abundant cryptic splicing associated with genomic features that promote splicing noise. We observe pervasive usage of low-fidelity splice sites, likely due to stochasticity in recruitment or binding of the spliceosome. These sites are most likely degraded in the nucleus rather than targeted by translation-dependent degradation processes, suggesting widespread surveillance and rapid quality control of non-productive RNA transcripts. Our findings provide unprecedented insights into the propensity for error in RNA processing mechanisms and the regulation of alternative splice sites across a gene.

Journal Article↗

PubMed2026

Interleukin-23 Receptor and Interleukin-17 Receptor A: Splice Variants, Isoforms and Their Relationship With Periodontitis-A Systematic Review and Bioinformatic Analysis.

This systematic review aimed to: (1) identify the splicing variants of IL23R and IL17RA reported in the literature; (2) perform a multiple alignment analysis to describe the isoforms of IL-23R and IL-17RA; and (3) compare the expression levels of IL-23R, IL-17RA, and their soluble isoforms (sIL-23R and sIL-17RA) in patients with periodontitis and periodontally healthy individuals. The study protocol followed PRISMA guidelines and was registered in PROSPERO (CRD420251267367). Six databases (PubMed, ScienceDirect, Scopus, Web of Science, EBSCO, and Google Scholar) were searched without restrictions on year or language. The descriptors used were: 'Interleukin-23 Receptor,' 'IL-23R,' 'Interleukin-17 Receptor A' 'IL-17RA,' 'Alternative Splicing,' 'Splice Variants,' 'Isoforms,' and 'Periodontitis.' The bioinformatics analysis was performed using CLUSTALW (V.1.83), InterPro and DeepTMHMM. Risk of bias was assessed with the QUIN and JBI tools for cross-sectional studies. Of 104 articles, four in vitro studies and eight cross-sectional studies were included. Qualitative analysis revealed that to date there are 32 splicing variants of the IL23R gene, while only one splicing variant has been reported for IL17RA. CLUSTALW, InterPro and DeepTMHMM analysis showed that these splicing variants result in 23 isoforms which can be soluble forms, complete intracellular peptides, truncated extracellular or intracellular peptides, or complete structures with truncated extracellular and/or intracellular domains. All studies had a low risk of bias. IL-23R and IL-17RA exhibit structural diversity resulting from alternative splicing, with IL-23R demonstrating significantly greater isoform complexity. However, the biological significance of these isoforms in periodontitis remains unclear and requires further investigation.

Humans↗

PubMed2025

Tandem splice acceptor sites: Profiling their relevance to human disease.

PURPOSE: Interpretation of variation, particularly the creation or disruption of tandem splice acceptor sites (NAGNnAG variants), challenges genomic medicine practice. METHODS: We analyzed the creation and disruption of dinucleotide AG sites within ±30 bases of natural splice-acceptor sites in the GRCh37 human reference genome. These results were compared with variant data from the ClinVar and gnomAD databases, as well as with data from 779 National Institutes of Health Undiagnosed Diseases Program study participants. Using RNA sequencing, we assessed the splicing at NAGNnAG variants for 107 of the Undiagnosed Diseases Program participants and compared the empirical data with SpliceAI predictions. RESULTS: Creation or disruption of NAGNnAG sites within 30 bases of the natural splice acceptor are enriched in ClinVar compared with gnomAD; however, such variants in the 2 databases are rarely differentiated by SpliceAI scores. Empirical evaluation via RNA sequencing analysis supported novel acceptor site usage from -21 to +30; splice-altering variants did not predominate in a specific region or have SpliceAI scores invariantly, suggesting increased spliceogenicity. CONCLUSION: NAGNnAG variants within 30 bp of the natural splice acceptor have a high probability of clinical relevance and are poorly contextualized for clinical utility. Their interpretation benefits from empirical evaluation via RNA analysis.

Humans↗

PubMed2019

A high resolution A-to-I editing map in the mouse identifies editing events controlled by pre-mRNA splicing.

Pre-mRNA-splicing and adenosine to inosine (A-to-I) RNA-editing occur mostly cotranscriptionally. During A-to-I editing, a genomically encoded adenosine is deaminated to inosine by adenosine deaminases acting on RNA (ADARs). Editing-competent stems are frequently formed between exons and introns. Consistently, studies using reporter assays have shown that splicing efficiency can affect editing levels. Here, we use Nascent-seq and identify ∼90,000 novel A-to-I editing events in the mouse brain transcriptome. Most novel sites are located in intronic regions. Unlike previously assumed, we show that both ADAR (ADAR1) and ADARB1 (ADAR2) can edit repeat elements and regular transcripts to the same extent. We find that inhibition of splicing primarily increases editing levels at hundreds of sites, suggesting that reduced splicing efficiency extends the exposure of intronic and exonic sequences to ADAR enzymes. Lack of splicing factors NOVA1 or NOVA2 changes global editing levels, demonstrating that alternative splicing factors can modulate RNA editing. Finally, we show that intron retention rates correlate with editing levels across different brain tissues. We therefore demonstrate that splicing efficiency is a major factor controlling tissue-specific differences in editing levels.

Adenosine Deaminase↗

PubMed2025

CAR-SPLASH identifies nascent pre-mRNA structures implicated in kinetic coupling and alternative splicing.

Pre-mRNA splicing is kinetically coupled to transcription as shown by the widespread effects of transcription speed on alternative splicing (AS) outcomes. The molecular basis for such kinetic coupling is incompletely understood, but one potential mechanism is through elongation rate-dependent alternative folding pathways of the nascent pre-messenger RNA (pre-mRNA). To search for RNA structures in nascent pre-mRNA, we modified Sequencing of Psoralen Crosslinked, Ligated And Selected Hybrids (SPLASH) [J. G. Ashley Aw et al., Mol. Cell 62, 603-617 (2016)] for use with Chromatin Associated RNA. We applied this method called Chromatin Associated RNA (CAR)-SPLASH to cells expressing wild-type and slow mutant RNA polymerase II and identified >3,000 intramolecular RNA duplexes of which >400 are proximal to splice sites. Antisense oligonucleotide (ASO) disruption of several such duplexes that sequester splice sites has a major impact on AS outcomes, even though the ASOs do not directly disrupt splice sites. ASO disruption of these regulatory elements that we designate "RNA kinetic switches" modified AS of NISCH Exon 18, GAK Exon 7, and MEGF8 Exon 14 in a way that depends on the rate of transcription elongation. We propose that these switches mediate kinetic coupling via the effects of transcription speed on folding of nascent RNA structures that modulate AS and that many nascent RNA structures can thereby serve as targets for splice-modifying ASOs.

RNA Precursors↗

PubMed2026

PUF60 is a Critical Regulator of PKM Splicing During Myogenesis.

Pyruvate kinase M (PKM) catalyzes the conversion of phosphoenolpyruvate to pyruvate in glycolysis and exists as two splice isoforms, PKM1 and PKM2, generated from alternative splicing of mutually exclusive exons 9 or 10, respectively. The expression balance between PKM1 and PKM2 is tightly regulated in a cell-type-specific manner. PKM1 is predominantly expressed in tissues such as skeletal muscle, heart, and brain, whereas PKM2 is prevalent in most other tissues and various cancer cells. Despite its importance, the trans-acting factors promoting exon 9 selection in a tissue-specific context remain largely unknown. Here, using a multi-color splicing reporter system for cell-based cDNA screening, we identified PUF60 as a novel trans-acting factor that promotes PKM1-type splicing. We also demonstrated that PUF60 induction and the resulting splicing switch are essential for myotube formation during C2C12 differentiation. This study establishes PUF60 as a critical regulator of muscle-specific splicing and provides new insights into the fundamental mechanisms governing skeletal muscle differentiation.

Animals↗

PubMed2026

Alternative splicing dysregulation in CAG repeat expansion diseases.

Alternative splicing of RNA is a highly regulated process that increases the complexity of gene expression, with disruption of splicing leading to significant disruption of cellular function and, ultimately, disease. This spliceopathy is exemplified by myotonic dystrophy type 1, a CTG repeat expansion disease, where dysregulation of alternative splicing drives core disease symptomatology. Recent studies across murine- and patient-derived disease models have demonstrated that similar alternative splicing changes are prevalent in CAG repeat expansion diseases, including Huntington's disease and multiple spinocerebellar ataxias. This review summarizes current knowledge on alternative splicing dysregulation in CAG repeat expansion diseases, highlights potentially disrupted genes and pathways, and discusses mechanisms through which alternative splicing dysregulation may contribute to disease pathogenesis and patient symptomatology.

Humans↗

PubMed2025

An Alternative Self-Splicing Intron Lifecycle Revealed by Dynamic Intron Turnover in Epichloë Endophyte Mitochondrial Genomes.

Self-splicing group I and II introns are selfish genetic elements that are widely yet patchily distributed across the tree of life. Their selfish behavior comes from super-Mendelian inheritance behaviors, collectively called "homing", which allow them to rapidly spread within populations to the specific genomic sites they home into. Observations of self-splicing intron evolutionary dynamics have led to the formulation of an intron "lifecycle" model where, once fixed in a population, the introns lose selection for homing and undergo an extensive period of degradation until their eventual loss. Here, we find that self-splicing introns are common in the mitochondrial genomes of Epichloë species, endophytic fungi that live in symbioses with grasses. However, these introns show substantial intron presence-absence polymorphism, with our analyses suggesting that these result from a combination of vertical intron inheritance coupled with multiple invasion and loss events over the course of Epichloë evolution. Surprisingly, we find little evidence for the extensive intron degradation expected under the existing intron lifecycle model. Instead, these introns in Epichloë appear to be lost soon after fixation, suggesting that Epichloë self-splicing introns have a different lifecycle. However, rapid intron loss alone cannot explain our results, indicating that additional factors, such as the evolution of homing suppressors, also contribute to Epichloë self-splicing intron dynamics. This work shows that self-splicing introns have more diverse evolutionary dynamics than previously appreciated.

Introns↗

PubMed2026

Tackling non-canonical splicing in arrhythmogenic cardiomyopathy to reduce the uncertain significance variants burden.

BACKGROUND: Splice-altering variants (SAVs), particularly those outside canonical splice sites, are an underappreciated contributor to inherited cardiovascular diseases. In arrhythmogenic cardiomyopathy (ACM), these variants frequently remain classified as of uncertain significance (VUS) due to limited predictive power and lack of transcript-level evidence, constraining genetic yield and clinical management. Our study aimed to determine the functional impact of SAVs in ACM genes and refine their classification using ACMG/AMP and ClinGen SVI criteria. METHODS: SAVs identified in 200 ACM probands underwent SpliceAI prediction, GTEx cardiac exon-usage annotation, and functional assessment using pSPL3-based minigene assays. Aberrant transcripts were quantified using Percent Splicing Alteration (PSA). Segregation data and ACMG/AMP criteria refined by ClinGen SVI were applied to integrate functional and clinical evidence for classification. RESULTS: Aberrant splicing was confirmed in 9/20 variants (45%), including synonymous, missense, and non-canonical intronic changes. SpliceAI scores correlated strongly with PSA values (R²=0.86). Case-control burden testing revealed significant enrichment of splice-altering variants in DSP, DSG2, DSC2 and FLNC. Integrating predictive algorithms with experimental validation and segregation analysis markedly enhances reclassification of 16/20 variants (80%). CONCLUSION: Splicing defects beyond canonical sites significantly shape ACM genetic landscape. Integrating predictive models with experimental validation clarifies uncertain variants bridging the gap between genomic uncertainty and clinical decision-making.

Humans↗

PubMed2026

Novel splice site variants in GBA1 are associated with Gaucher disease and genotype-phenotype correlations.

BACKGROUND: Variants in GBA1 are associated with neurodegenerative disease. This study aimed to explore pathogenic GBA1 variants. METHODS: Four patients with progressive myoclonic epilepsy (PME) and extremely low β-glucosidase levels were recruited. Whole-exome sequencing and long-range PCR were performed to identify GBA1 variants. Bioinformatic analyses were used to predict the impact of the identified variants. A literature review was performed to explore the genotype-phenotype correlations. GBA1 expression data across different brain regions and developmental stages were analyzed using the BrainSpan database. RT-PCR was performed to verify the splicing effects. RESULTS: Compound heterozygous GBA1 variants were identified in four patients. Five distinct variants were detected, including two novel splice site variants (c.308-2A>G and c.762-2A>C) and three previously reported variants. All identified variants were rare or absent in gnomAD. Splice site variants c.308-2A>G and c.762-2A>C were predicted to cause aberrant splicing. Minigene-based splicing assays coupled with RT-PCR and Sanger sequencing confirmed that both variants cause complete exon skipping (exon 4 and exon 7, respectively). All patients presented with PME onset in childhood/adolescence, intellectual regression, low β-glucosidase, and diffuse brain atrophy and were subsequently diagnosed with Gaucher disease type 3. GBA1 expression in the brain showed two distinct peaks: one in infancy and another after five years of age. The onset age of PME aligned with the second GBA1 expression peak (after five years of age). CONCLUSION: This study identified compound heterozygous GBA1 variants, including two novel candidate pathogenic splice site variants, in Gaucher disease type 3 patients, expanding the known mutational spectrum.

Humans↗

PubMed2026

Suppression of HIV-1 replication in CEM-A cell cultures by trans-splicing group I introns targeting PAS/PBS sequences and conditionally expressing ΔN-Bax.

Anti-HIV group I introns containing antisense guide sequences directed against the HIV-1 primer activation signal and primer-binding site (PAS/PBS) were designed and evaluated. Because PAS/PBS sequences are present in the viral RNA species examined, these RNAs can serve as trans-splicing substrates. The introns were active against both artificial target RNAs and viral RNA generated during infection. Cleavage and degradation of targeted viral RNA may have contributed to suppression, whereas inclusion of a 3' exon encoding the proapoptotic protein ΔN-Bax was associated with increased programmed cell death and may have augmented suppression of viral replication. In cultured CEM-A cells, transgene expression of these introns markedly suppressed HIV-1 replication, with p24 levels falling below the assay detection limit in selected clones. RESULTS: RT-PCR and sequence analysis detected splice products containing the expected PAS/PBS junctions. In the dual-luciferase assay, intron expression reduced normalized Gaussia luciferase signal by approximately 70% relative to the negative control. Qualitative Annexin V imaging and caspase-3 assays were consistent with infection-dependent apoptosis after ΔN-Bax splice-product formation. Transient expression of each intron in HEK293T cells followed by infection with VSV-G-pseudotyped HIV-1NL4-3 at an MOI of 2 reduced p24 levels by approximately 50% at 4 days post-infection. Construct 128L produced the strongest RT-PCR band under the tested conditions and was selected for subsequent experiments. A canonical splice product and a low-abundance noncanonical splice product were detected; both involved the intended HIV-derived target RNA, although transcriptome-wide off-target splicing was not assessed. Heterogeneous transformed HEK293T populations showed an approximately 2-log10 reduction in p24. In selected clonal HEK293T and CEM-A lines, p24 was below the assay detection limit at the measured endpoints, including up to 90 days after infection in some CEM-A clones. CONCLUSIONS: PAS/PBS-targeting group I introns suppressed HIV-1-associated p24 production in the tested cell-culture models. Linking the introns to a ΔN-Bax 3' exon was associated with infection-dependent apoptosis and may further limit viral replication and spread. The use of highly conserved, functionally constrained target sequences may reduce the likelihood of escape, but viral evolution and transcriptome-wide off-target effects were not assessed. This conditional death-upon-infection strategy warrants further evaluation in primary-cell and in vivo models.

Humans↗

PubMed2025

PRMT5 regulates alternative splicing of TCF3 under hypoxia to promote EMT and invasion in breast cancer.

Tumor hypoxia induced alterations in the epigenetic landscape and alternative splicing influence cellular adaptations. PRMT5 is a type II protein arginine methyltransferase that regulates several tumorigenic events in many cancer types. However, the regulation of PRMT5 and its direct implication on aberrant alternative splicing under hypoxia remains unexplored. In this study, we observed hypoxia-induced upregulation of PRMT5 via the CTCF in human breast cancer cells. Further, PRMT5-mediated symmetric arginine dimethylation H4R3me2s and H3R8me2s directly regulated the alternative splicing of TCF3. Under hypoxia, PRMT5-mediated histone dimethylation at the intronic conserved region (ICR) present between TCF3 exon 18a and exon 18b recruits DNMT3A, resulting in DNA methylation. DNA methylation at the TCF3-ICR is recognized and bound by MeCP2 resulting in RNA-Pol II pausing, promoting the recruitment of the negative splicing factor PTBP1 to the splicing locus of TCF3 pre-mRNA. PTBP1 promotes the exclusion of exon 18a which results in the production of the pro-invasive TCF3-18B (E47) isoform which promotes EMT and invasion of breast cancer cells under hypoxia. Collectively, our results indicate PRMT5-mediated symmetric arginine dimethylation of histones regulates alternative splicing of TCF3 gene thereby enhancing EMT and invasion in breast cancer hypoxia.

Humans↗