Search Results (350)

Background/Objectives: Therapeutic strategies for Neurofibromatosis Type I (NF1) that correct the underlying pathogenic NF1 variant hold promise for restoring neurofibromin function, reducing tumor burden, and improving patient outcomes by addressing the root cause of the disease rather than its symptoms. Beyond gene editing, transcript reprogramming via RNA trans-splicing has gained attention, particularly with the recent FDA approval of two trans-splicing-based drugs for IND phase 1/2a trials. This study tests whether trans-splicing group I intron ribozymes from Tetrahymena thermophila can be used to repair pathogenic variants of NF1 (pre-)mRNA by 3′-tail replacement. Methods: Splice sites on the NF1 mRNA were identified computationally and validated biochemically, and an efficiency-enhancing Extended Guide Sequence (EGS) of the corresponding ribozyme was identified in a combinatorial experiment. Results: The correct trans-splicing product of this ribozyme was validated in HEK293 NF1−/− cells expressing mNf1. Conclusions: This study established a splice site and activity-enhancing extended guide sequences for the repair of NF1 mRNA. Further optimization of the ribozyme, as well as improved delivery methods, may establish ribozyme-based RNA repair as a viable strategy for NF1 treatment. Full article

Sulforaphane (SFN) is a bioactive compound belonging to the isothiocyanate family, known for its neuroprotective properties. While transcriptomic studies have highlighted SFN’s role in regulating gene expression, its impact on alternative splicing (AS), a key regulatory mechanism in neuronal metabolism, remains underexplored. In this study, we investigated whether SFN pre-treatment influences mRNA splicing patterns in an in vitro neuronal model using retinoic acid (RA)-differentiated SH-SY5Y cells. Using a dedicated RNA-seq-based splicing analysis pipeline, we identified 194 differential alternative splicing events (DASEs) associated with SFN treatment. Gene Ontology enrichment revealed significant over-representation of DNA repair processes. To better understand the functional implications, we integrated in silico predictions of premature stop codons, DASE/miRNA hybridizations, and DASE/RNA-binding protein (RBP) motif occurrences. Our findings suggest that SFN may modulate splicing of key DNA repair genes, contributing to protecting neurons against DNA damage. These preliminary results underscore a novel layer of SFN’s molecular effects and propose it as a valuable adjuvant in physiological conditions to enhance cellular health. Further studies are warranted to dissect the mechanistic underpinnings of SFN-mediated AS and its relevance in DNA-damage-related disorders. Full article

For 40 years, Intron Retention (IR) was dismissed as splicing noise and is now recognized as a dynamic and evolutionarily conserved mechanism of post-transcriptional gene regulation. Unlike canonical splicing, which excises all introns from pre-mRNAs, IR selectively retains intronic sequences, albeit at seemingly random places; however, current research now reveals that this process is strategic in its retention. IR influences mRNA stability, localization, and translational potential. Retained introns can lead to nonsense-mediated decay, promote nuclear retention, or give rise to novel protein isoforms that contribute to expanding proteomic and transcriptomic profiles. IR is finely regulated by splice site strength, splicing regulatory elements, chromatin structure, methylation patterns, RNA polymerase II elongation rates, and the availability of co-transcriptional splicing factors. IR plays critical roles in cell-type and tissue-specific gene expression with observed patterns, particularly during neuronal, cardiac, hematopoietic, and immune development. It also functions as a molecular switch during cellular responses to environmental and physiological stressors such as hypoxia, heat shock, and infection. Dysregulated IR is increasingly associated with cancer, neurodegeneration, aging, and immune dysfunction, where it may alter protein function, suppress tumor suppressor genes, or generate immunogenic neoepitopes. Experimental and computational tools like RNA-seq, RT-PCR, IRFinder, and IntEREst have enabled transcriptome-wide detection and validation of IR events, uncovering their widespread functional roles. This review will examine current knowledge on the function, regulation, and detection of IR, and also summarize recent advances in understanding its role in both normal and pathophysiological settings. Full article

Fanconi anemia (FA) is a DNA repair deficiency disorder associated with genomic and chromosomal instability and a high cancer risk. In a small percentage of cases, FA is caused by biallelic pathogenic variants (PVs) in the BRCA2/FANCD1 gene, defining the FA-D1 subtype. Experimental and epidemiologic data indicate that the complete absence of BRCA2 is incompatible with viability. Therefore, cells from individuals affected with FA caused by biallelic BRCA2 PVs must have a residual BRCA2 function. This activity may be maintained through hypomorphic missense mutations, translation termination–reinitiation associated with a translational stop mutation, or other non-canonical or uncommon translation initiation and elongation events. In some cases, however, residual BRCA2 function is provided by alternatively or aberrantly spliced BRCA2 transcripts. Here, we review and debate aspects of the contribution of splicing in the 5′ segment to BRCA2 functions in the context of PVs affecting this largely intrinsically disordered protein region, with a focus on recent findings in individuals with FA-D1. In this Perspective, we also discuss some of the broader biological implications and open questions that arise from considering 5′-terminal BRCA2 splicing in light of old and new findings from FA-D1 patients and beyond. Full article

Fruiting body formation in edible fungi is a critical development process for both scientific understanding and industrial cultivation, yet the underlying genetic mechanisms remain poorly elucidated. This study aimed to identify key genes regulating monokaryotic fruiting in Flammulina filiformis. A genetic segregation population was constructed through selfing purification and hybrid segregation of the FF002 strain, followed by mapping candidate genes with bulked segregant analysis sequencing (BSA-seq). A 10 kb genomic region on scaffold19 was identified, pinpointing the gene FV-L110034160, which encodes a U2 snRNP complex component involved in pre-mRNA splicing. A T→G SNP located 121 bp downstream of the ATG codon caused a serine-to-alanine substitution, disrupting a conserved domain and altering fruiting phenotypes. Phylogenetic analysis further revealed conservation of this gene in fungal genera. These findings elucidate a key regulatory gene controlling monokaryotic fruiting in F. filiformis, providing novel insights into fruiting body formation mechanisms and establishing a foundation for genetic studies in other edible fungi. Full article

Aberrant activation of Wnt/β-catenin signaling, frequently caused by oncogenic mutations, plays a crucial role in the development, progression, and therapy resistance of gastric, esophageal, hepatic, pancreatic, and colorectal cancers. Concurrently, circular RNAs (circRNAs), produced by back-splicing of precursor mRNAs (pre-mRNAs), have emerged as critical modulators of this pathway. Accumulating evidence indicates that specific circRNAs regulate Wnt/β-catenin signaling by sponging microRNAs, interacting with RNA-binding proteins, modulating protein function, and altering the expression of pathway components. Some circRNAs are also subject to feedback regulation by Wnt signaling itself. Clinically, tumor-associated circRNAs are present in body fluids and correlate with disease stage, metastatic burden, and patient survival, underscoring their potential as early and minimally invasive biomarkers. Moreover, targeting oncogenic circRNAs has shown promise in preclinical models of Wnt-driven gastrointestinal malignancies. In this review, we summarize the current understanding of the interplay between circRNAs and Wnt/β-catenin signaling in gastric and esophageal cancers. We discuss the translational challenges and emerging opportunities for biomarker development and targeted therapy. Full article

In plants, alternative splicing (AS) is a crucial post-transcriptional regulatory mechanism that generates diverse mature transcripts from precursor mRNA, with the resulting functional proteins regulating a wide range of plant life activities. The regulation of AS is intricate and complex, playing pivotal roles in controlling plant biological processes like seed germination, flowering time control, growth, and development, as well as responses to abiotic and biotic stresses. The regulation of AS is a multilayered and intricately coordinated network system, primarily involving two core components: cis-regulatory elements and trans-acting factors on pre-mRNA. The precise execution of AS relies on the splicing factors by recognizing cis-elements to modulate splice site selection. Regulated by their own sequence variation, environmental cues, and identification of different spliceosomes, functional genes enable AS to achieve precise spatiotemporal regulation, thereby allowing plants to dynamically respond to developmental signals and environmental challenges. Here, we provide a comprehensive overview of AS patterns, functional genes, and splicing factors undergoing AS and its regulatory mechanisms during different processes, highlighting how AS-mediated gene regulation contributes to plant development and stress response, and offering potential strategies for improving plant adaptation by manipulation of AS-regulated genes. Full article

While the U1 small nuclear ribonucleoprotein (snRNP) plays a crucial role in early spliceosome assembly, the mechanisms by which it coordinates with other splicing factors for efficient assembly remain elusive. This study aimed to examine the role of the Swt21 protein in regulating U1 snRNP in Saccharomyces cerevisiae. Swt21p was required for efficient pre-mRNA splicing both in vivo and in vitro. Deletion of SWT21 altered the splicing patterns of two-intron SUS1 RNA, causing intron retention and exon skipping. Spliceosome assembly analysis revealed that in the pre-B complex, the levels of U1 protein components, as well as U1 RNA, were decreased following SWT21 deletion, highlighting the compromised stability of U1 snRNP during this stage. Consistently, in the absence of Swt21p, free isoform of U1 component Nam8p was observed, and its proper nuclear localization was disrupted, demonstrating the functional importance of Swp21p for the stable association of Nam8p with U1 snRNP. Moreover, Swt21p remained primarily in a free state under physiological conditions and did not associate with the pre-B complex. Additionally, TAP analysis revealed that Swt21p-associated proteins are involved in cellular processes beyond splicing. These findings collectively indicate that Swt21p functions as a spliceosome regulator rather than a core component and support a model wherein Swt21p contributes to U1 snRNP stability during early spliceosome assembly. Full article

The expansion of the polyglutamine tract in ATXN1 contributes to the pathogenesis of SCA1. ATXN1 functions as a transcriptional regulator that interacts with multiple transcription factors, and transcriptional dysregulation has been observed in SCA1. In addition, splicing dysregulation has been identified in cells derived from SCA1 patients and model mouse tissues. Although ATXN1 binds to RNA and splicing factors, its direct involvement in pre-mRNA splicing remains unclear. Here, we demonstrate that ATXN1 regulates the alternative splicing of several minigenes. Using an Mbnl1 minigene, we found that neither expansion nor deletion of the polyglutamine tract affected ATXN1-mediated splicing regulation. Deletion analysis revealed that its splicing regulatory activity involves a central region of ATXN1, the AXH domain, and a nuclear localization signal in the C-terminal region. The AXH domain alone failed to exhibit splicing regulatory activity, whereas the central region demonstrated weak but significant splicing regulation. Full regulatory function required at least one of these regions, suggesting their redundant role in splicing modulation. Importantly, we newly identified the central region as mediating RNA binding. These findings suggest a novel role for ATXN1 in alternative splicing, providing new insights into the mechanisms underlying SCA1 pathogenesis. Full article

Background: Preeclampsia (PE) is a pregnancy-specific disorder and a leading cause of maternal and fetal morbidity and mortality. Impaired trophoblast invasion is a hallmark of PE, and alternative splicing (AS) is crucial for trophoblast differentiation and placental development. However, the exact mechanisms of AS in PE remain poorly understood. Methods: To elucidate AS-mediated regulatory pathways in PE, a total of 38 fresh-frozen placental samples, including 13 pre-eclampsia samples and 25 normal control samples, were collected from Renmin Hospital of Wuhan University between 1 February and 30 July 2022. We performed transcriptome sequencing of seven PE and seven normal placentas to identify differentially spliced events. After quality control and adapter trimming, raw sequencing reads were aligned to the human reference genome using STAR. Differential exon usage was analyzed using DEXSeq (version 1.36.0), and exons with an adjusted p-value < 0.05 and a fold change greater than 2 or less than 0.5 were considered significantly differentially spliced. Functional assays, including CCK8, colony formation, and cell cycle analyses, were conducted to assess trophoblast proliferation, whereas wound healing and Transwell assays were used to evaluate trophoblast migration and invasion using the HTR-8/SVneo cell line. RNA immunoprecipitation sequencing (RIP-seq) and RNA stability assays were employed to investigate mRNA interactions and stability. Results: Insulin-like growth factor 2 mRNA-binding protein 3 (IGF2BP3) emerged as a key RNA-binding protein associated with alternative splicing regulation, intersecting both AS-related candidate genes and known splicing factors, although it is not a classical splicing factor itself. IGF2BP3 overexpression markedly enhanced HTR-8/SVneo trophoblast proliferation, migration, and invasion while suppressing ROS activation. RNA-seq, RIP-seq, and RNA stability assays revealed that IGF2BP3 directly interacts with and enhances the stability of PDE3A mRNA. Functional rescue experiments confirmed that PDE3A knockdown partially abrogated IGF2BP3-mediated trophoblast progression. Furthermore, miR-196a-5p was identified as a negative regulator of IGF2BP3 via miRNA inhibitor/mimic transfection, qRT-PCR, and functional assays, confirming that miR-196a-5p overexpression downregulates IGF2BP3, thereby impairing trophoblast migration and proliferation. Notably, restoring IGF2BP3 expression reversed these inhibitory effects. Conclusions: Our findings reveal a previously unrecognized regulatory axis in PE in which miR-196a-5p suppresses IGF2BP3 expression, leading to PDE3A mRNA destabilization and impaired trophoblast function. This study offers mechanistic insights into PE pathogenesis and identifies IGF2BP3 as a potential therapeutic target. Full article

Precursor messenger RNA (pre-mRNA) splicing is a critical post-transcriptional regulatory mechanism in gene expression. The precise splicing of pre-mRNAs is essential for plant development and responding to genetic and environmental signals. In plant sexual reproduction, gene expression regulation relies on the accurate processing of pre-mRNAs, which is fundamental for coordinating developmental programs. The alternation of generations in plants involves two key phases: gametophyte development, which produces gametes, and fertilization, which leads to the formation of a diploid sporophyte. Gametophyte and embryo development represent essential processes in plant sexual reproduction. This review focuses on summarizing and analyzing the current evidence regarding the role of pre-mRNA splicing in plant sexual reproduction, with an emphasis on its involvement in gametophyte formation and embryo development. Future challenges in understanding RNA splicing regulation in plant sexual reproduction are also discussed, particularly in modulating splicing factor levels and activities and identifying target mRNAs and non-coding RNAs regulated by these factors. This review provides crucial insights into the molecular mechanisms of plant reproductive development and offers a theoretical basis for improving plant fertility and adaptability via RNA splicing regulation. Full article

This study investigated whether exercise training improved cholesterol metabolism through modifying alternative splicing of the low-density lipoprotein receptor (LDLR). Blood lipids and expressions of LDLR splice variants were compared between exercise-trained and non-trained young adults with normal and high cholesterol. The expression of LDLR splice isoforms were examined using RT-PCR and the histone H3K36me3 by CHIP-assay in mouse liver following a 13-week normal or high-cholesterol-diet combined with or without 8 weeks of aerobic exercise-training. The influence of histone modifications on LDLR alternative splicing was examined in HepG2 cells (human liver cell-line). Expression levels of LDLR deletions in exons 4 and 12 (LDLR-∆Exon4 and LDLR-∆Exon12) were significantly higher in the obese adults with high-cholesterol. These LDLR splice variants were significantly lower in the exercise-trained than non-trained group with normal cholesterol. Thirteen weeks of high-cholesterol feeding increased LDLR-∆Exon14 expression in mice, which was diminished after 8 weeks of exercise training. When H3-K36me3 or the MORF-related gene on chromosomes 15 were overexpressed and interfered, the levels of LDLR-∆Exon4 and LDLR-∆Exon12 expression in HepG2 cells were significantly augmented and inhibited, respectively. Hypercholesterolemia was associated with augmented expressions of LDLR splice variants in obese adults and following high-cholesterol diet in mice. Aerobic exercise training prevented and reversed the dyslipidemia-related alternative splicing of LDLR pre-mRNA. The histone modifications contributed to the alternative splicing. Full article

Cancer is biologically diverse, highly heterogeneous, and associated with molecular alterations, significantly contributing to mortality worldwide. Currently, cancer patients are subjected to single or combination treatments comprising chemotherapy, surgery, immunotherapy, radiation therapy, and targeted therapy. Chemotherapy remains the first line of treatment in cancer but faces a major obstacle in the form of chemoresistance. This obstacle has resulted in relapses and poor patient survival due to decreased treatment efficacy. Aberrant pre-mRNA alternative splicing can significantly modulate gene expression and function involved in the resistance mechanisms, potentially shaping the intricate landscape of tumour chemoresistance. Thus, novel strategies targeting abnormal pre-mRNA alternative splicing and understanding the molecular mechanisms of chemotherapy resistance could aid in overcoming the chemotherapeutic challenges. This review first highlights drug targets, drug pumps, detoxification mechanisms, DNA damage response, and evasion of apoptosis and cell death as key molecular mechanisms involved in chemotherapy resistance. Furthermore, the review discusses the progress of research on the dysregulation of alternative splicing and molecular targets involved in chemotherapy resistance in major cancer types. Full article

Alternative splicing is one of the processes that contributes to producing a vast protein diversity from the limited number of protein-coding genes in higher eukaryotes. The Methyl CpG Binding Protein 2 (Mecp2) gene, whose mutations cause Rett syndrome, generates two protein isoforms, MeCP2E1 and MeCP2E2, by alternative splicing. These isoforms likely possess non-redundant functions. However, the molecular mechanism for Mecp2 pre-mRNA alternative splicing remains to be understood. Here, we analyzed the alternative splicing mechanism of MeCP2 pre-mRNA and found that exon 2 is efficiently recognized through adjacent strong splice sites. In addition, exonic splicing enhancer (ESE) in exon 2 plays an important role in exon 2 inclusion, which is highly likely to be mediated by SRSF9. Full article

Alzheimer’s disease (AD) is the most common form of dementia, characterized by β-amyloid (Aβ) plaques and neurofibrillary tangles, leading to neuronal loss and cognitive impairments. Recent studies have reported the dysregulation of RNA splicing in AD pathogenesis. Our previous transcriptomic study demonstrated the neuroprotective effect of the phytocannabinoid cannabinerol (CBNR) against the cell viability loss induced by Aβ in differentiated SH-SY5Y cells. This study also highlighted the deregulation of genes involved in mRNA splicing after Aβ exposure or CBNR pre-treatment. Here, we investigated whether CBNR could restore the splicing defects induced by Aβ in an AD in vitro model. Using the rMATS computational tool for detecting differential alternative splicing events (DASEs) from RNA-Seq data, we obtained 96 DASEs regulated in both conditions and, remarkably, they were all restored by CBNR pre-treatment. The pathway analysis indicated an over-representation of the “Alzheimer’s disease–amyloid secretase pathway”. Additionally, we observed that Aβ exposure increased the frequency of retained introns (RIs) among the shared DASEs, and that this frequency returned to normality by CBNR pre-treatment. Interestingly, most of these RIs contain a premature in-frame stop codon within the RNA sequence. Finally, analyzing the DASE regions for miRNA hybridization, we found 33 potential DASE/miRNA interactions that were relevant in AD pathogenesis. These findings revealed a novel trans-gene regulation by CBNR, potentially explaining part of its neuroprotective role. This is the first study demonstrating the involvement of a cannabinoid in the regulation of mRNA splicing in an AD model. Full article