Search Results (113)

RNA N⁶-methyladenosine (m⁶A) is a prevalent epitranscriptomic modification that governs plant growth, development, and environmental adaptation. This review synthesizes recent advances in understanding the molecular mechanisms and biological functions of m⁶A in plants. The m⁶A landscape is dynamically regulated by methyltransferases (writers), demethylases (erasers), and m⁶A-binding proteins (readers), which collectively influence mRNA stability, translation efficiency, alternative polyadenylation (APA), and chromatin crosstalk. Functionally, m⁶A integrates diverse developmental processes—including embryogenesis, organogenesis, flowering, fruit ripening, and leaf senescence—with abiotic stress responses such as salt, drought, cold, and heat. Notably, m⁶A modification exhibits remarkable species-, cultivar-, and tissue-specific plasticity, enabling precise spatiotemporal gene regulation. Recent breakthroughs have revealed bidirectional crosstalk between m⁶A and histone modifications, forming a multi-layered regulatory network, while emerging concepts including phase separation, RNA structure dynamics, and stress memory further expand the functional repertoire of m⁶A. Despite significant progress, plant epitranscriptomics remains mechanistically underexplored, with critical gaps persisting in our understanding of translation initiation mechanisms, upstream regulatory signals controlling writers/erasers activities, and the functional significance of individual m⁶A sites. This review provided systematic insights into the complexity and specificity of m⁶A regulation in plants, offering a theoretical foundation for future efforts to decipher and ultimately manipulate this epitranscriptional layer for crop improvement. Full article

Background: Tumor hypoxia in non-small cell lung cancer (NSCLC) promotes malignant progression and treatment resistance by enhancing abnormal vasculature, invasiveness, and metastasis. However, the molecular mechanisms underlying hypoxia-driven tumor progression remain incompletely understood. Methods: In this study, patient samples, cell lines, single-cell transcriptomic data, and spatial transcriptomic data were comprehensively analyzed to investigate hypoxia-associated molecular alterations in NSCLC. Results: A global trend toward shortened 3’ untranslated regions (3’UTRs) was observed in hypoxic tumors. Analysis of hypoxia-related alternative polyadenylation (APA) events revealed preferential usage of proximal polyadenylation sites (poly(A) sites, PASs) in CARM1. Shortening of the CARM1 3’UTR was associated with hypoxia and may serve as a candidate biomarker. This APA event may reduce putative microRNA (miRNA) binding sites and contribute to increased CARM1 expression, while potentially influencing the expression of hypoxia-related genes such as SELENBP1. Drug sensitivity analysis further suggested that patients with shorter CARM1 3’UTRs may exhibit differential responses to cisplatin chemotherapy. Moreover, single-cell and spatial transcriptomic analyses demonstrated enhanced interactions between hypoxic tumor cells and fibroblasts, highlighting a potential role for APA in remodeling the hypoxic tumor microenvironment. Conclusions: Our findings identify hypoxia-related APA features and characterize hypoxia-associated alterations within the NSCLC tumor microenvironmen, providing new insights into the molecular landscape of hypoxia-associated tumor progression. Full article

The poly(A) tail of mRNA plays a vital role in mRNA transcript stability, translational efficiency, and immunogenicity. Co-transcriptionally polyadenylated in vitro transcribed (IVT) mRNAs typically contain poly(A) tails of 50–120 nucleotide tail length due to limitations in production of template pDNA with longer poly(A) sequences. In contrast, post-transcriptional enzymatic polyadenylation of mRNA with poly(A) polymerase (PAP) presents a modular alternative to increase the tail length. However, the lack of real-time control strategies for PAP-mediated tailing has limited its broader applicability in mRNA production. Here, we develop a methodology for controlling poly(A) tail length in post-transcriptional polyadenylation of mRNA that uses adenosine triphosphate (ATP) consumption measured at-line to predict the poly(A) tail length. We establish a novel analytical method based on monolith reverse-phase chromatography to validate the poly(A) predictions. We were able to produce longer poly(A) tails and accurately determine their length in 300–700 nt range. The resulting longer poly(A) tailed reporter mRNAs outperformed the encoded and shorter poly(A) tailed mRNAs in cell-based assays. This work presents a new strategy for controlled post-transcriptional polyadenylation using ATP consumption as a process control metric, an approach which may in future be expanded to other NTP-dependent enzymatic conversions. Full article

Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by genetic heterogeneity. Post-transcriptional regulation—particularly alternative polyadenylation (APA)—plays a critical role in the pathogenesis of ASD. APA controls mRNA stability, translational efficiency, and subcellular localization through modulating the length of the 3′ untranslated region of mRNA. APA profiling can uncover functionally relevant post-transcriptional alterations often missed by conventional gene expression analyses. However, current ASD analyses still largely rely on differential gene expression or individual APA event detection, which ignores the collective explanatory power of ASD risk genes or co-dysregulated functional gene modules within specific cell types. In this study, we present an integrative computational framework that combines matrix factorization and machine learning to identify ASD-associated gene modules driven by APA and to predict cell-type-specific ASD-related cells. Applied to human brain single-nucleus RNA sequencing (snRNA-seq) data, our approach systematically uncovers APA regulatory patterns that are specific to cell type, brain region, and sex in ASD. The identified APA modules are significantly enriched in pathways related to synaptic function, neurodevelopment, and immune response, with the strongest signals observed in excitatory neurons of the prefrontal cortex. Using APA genes from these modules as features, we built a classification model that effectively distinguishes ASD cells from normal cells. Moreover, we found that integrating APA with gene expression—two complementary modalities—substantially improves prediction accuracy, underscoring APA as an independent and biologically informative regulatory layer. Our work delineates a high-resolution APA regulatory landscape in ASD, offering novel insights and potential therapeutic avenues beyond transcriptional abundance. Full article

Alternative splicing (AS) and alternative polyadenylation (APA), as post-transcriptional regulatory mechanisms, are involved in various biological processes through the generation of transcript variants. However, genome-wide studies of AS and APA during spleen development are scarce. This study aimed to characterize transcript diversity and changes in transcript isoforms in the spleen at two developmental stages using full-length isoform sequencing integrated with short-read RNA sequencing. We revealed widespread transcript diversity and identified 17,294 unannotated transcripts, most of which originated from known genes in the current pig genome annotation. The top 500 genes with the highest isoform diversity were mainly associated with disease occurrence and immune function, as revealed by Kyoto Encyclopedia of Genes and Genomes enrichment analysis. We also observed changes in major transcript usage and polyadenylation site selection during spleen development. Our results indicated that genes regulated immunological development mainly by switching dominant transcript isoforms rather than altering overall expression levels. In addition, genes exhibited a tendency of age-dependent preference for distal polyadenylation sites. Furthermore, transcription factors important for spleen development were identified, and the regulatory axes MYBL2/WEE1 and E2F1/WEE1 were constructed for the first time using molecular biology techniques. These findings not only refined the current pig genome annotation, but also provided a foundation for exploring the molecular mechanisms responsible for spleen development. Full article

Quiescence is a reversible, non-proliferative cellular state that enables survival under nutrient limitation while preserving the capacity to resume growth. Rather than representing a passive default, quiescence is an actively regulated program conserved from unicellular eukaryotes to metazoans. This review focuses on the nuclear mechanisms underlying quiescence entry, maintenance, and exit, with primary emphasis on mechanistic insights from yeast models while highlighting conserved principles in multicellular systems. Across species, quiescence is characterized by global transcriptional repression, chromatin compaction, and the extensive reorganization of nuclear architecture, coordinated by nutrient-sensing pathways centered on TOR/mTOR signaling. We discuss how transcriptional reprogramming is achieved through redistribution of RNA polymerases, dynamic transcription factor activities, and large-scale remodeling of histone modifications, alongside repressive chromatin formation. In parallel, post-transcriptional mechanisms—including intron retention, alternative polyadenylation, and accumulation of non-coding RNAs—fine-tune gene expression while limiting biosynthetic output. We further examine how changes in nuclear organization, such as nucleolar condensation, condensin-mediated chromosome rearrangements, and telomere hyperclusters, support long-term viability and genome stability. Collectively, this review highlights nuclear dynamics as an integrative regulatory layer that links metabolic state to cellular identity, adaptability, and long-term survival, with broad implications for development, stem cell function, and disease. Full article

Significant differences in reproductive performance exist between meat-type ducks (e.g., Qiangying Duck, QD) and laying-type ducks (e.g., Shaoxing Duck, SD). The molecular mechanisms underlying these differences, particularly concerning ovarian development and function, remain incompletely understood. This study aimed to comprehensively characterize the ovarian transcriptomes of these two duck types, focusing on differential gene expression and post-transcriptional regulatory events. We performed an integrated full-length transcriptome analysis of ovarian tissues from these two breeds using PacBio SMRT and Illumina sequencing. Bioinformatic analyses, including functional annotation, differential expression analysis, and the identification of APA events, were used. We discovered substantial breed-specific differences in alternative polyadenylation (APA), with SD ducks exhibiting significant 3′UTR shortening in 3799 genes and 3′UTR lengthening in 1626 genes compared to QD. The integrated analysis of differential gene expression and APA events highlighted key genes related to steroid hormone synthesis (HMGCS1, DHCR24), lipid metabolism (SCD), signal transduction (HRAS), and antioxidant defense (SOD1). The functional enrichment implicated critical pathways such as mitochondrial energy metabolism, oxidative phosphorylation, and fatty acid degradation. Our study provides a comprehensive atlas of post-transcriptional regulation in the duck ovary and reveals APA as a crucial process of gene regulation. APA may contribute to the differential ovarian function and egg-laying capacity between meat and laying ducks, thus offering valuable targets for genetic selection. Full article

The identification of mRNA isoforms in biological samples is crucial for studying tissue- and cell-specific isoform expression, activity of tissue-specific promoters, alternative splicing events, and alternative polyadenylation signals in genes. For single or several genes, expressed mRNA isoforms can be found using RT-PCR and RT-qPCR. Available transcriptome short-read archives deposited in GenBank or as laboratory data can be used to identify mRNA isoforms instead of or prior to wet analysis by other methods in eukaryotic organisms with annotated genomes. However, isoform expression analysis requires advanced bioinformatics skills and may be time-consuming. In addition, this analysis generates a large amount of unnecessary data. To detect mRNA isoforms encoded by one gene of interest, screening of expressed mRNAs in NGS data can be simplified by mapping NGS short reads to a single-gene or transcript sequence. Using single-gene/transcript mapping, we analyzed the expression of the Otx gene at the mRNA isoform level in some embryonic and adult tissue mRNA libraries of the sea urchin Strongylocentrotus purpuratus available in GenBank. The presence of expressed Otx mRNA isoforms was confirmed by RT-qPCR in the same tissues and at the same developmental stages of the closely related species Strongylocentrotus intermedius. We showed that single-gene/transcript mapping is a suitable approach for qualitative evaluation of the expression of mRNA isoforms and recognition of at least two expressed isoforms in the same biological sample. Full article

Human embryonic stem cell (hESC) neural differentiation involves extensive APA; however, reliance on short-read sequencing in prior studies has offered only a limited view of its complexity and dynamic regulation. Here, we integrated Oxford Nanopore (ONT) long-read sequencing with Illumina short-read sequencing to systematically map the APA landscape during early hESC neural differentiation. Our hybrid approach uncovered remarkable transcriptomic complexity, identifying 20,823 novel transcripts and 8241 previously unannotated poly(A) sites (PASs). We characterized distinct dynamic patterns of 3′ UTR-APA across differentiation and pinpointed SOX11 as a key APA-regulated target. Furthermore, we observed stage-specific enrichment of intronic APA in NPCs, as exemplified by SLC1A3, and performed a comprehensive, large-scale identification of high-confidence exon APA events. These results substantially expand the catalog of PASs during human neural differentiation and provide new insights into how APA-mediated post-transcriptional regulation contributes to cell-fate decisions. Full article

The Xenopus oocyte has long served as a versatile and powerful model for dissecting the molecular underpinnings of reproductive and developmental processes. Its large size, manipulability, and well-characterized cell cycle states have enabled generations of researchers to illuminate key aspects of oocyte maturation, fertilization, and early embryogenesis. This review provides an integrated overview of the cellular and molecular events that define the Xenopus oocyte’s transition from meiotic arrest to embryonic activation—or alternatively, to programmed demise if fertilization fails. We begin by exploring the architectural and biochemical landscape of the oocyte, including polarity, cytoskeletal organization, and nuclear dynamics. The regulatory networks governing meiotic resumption are then examined, with a focus on MPF (Cdk1/Cyclin B), MAPK cascades, and translational control via CPEB-mediated cytoplasmic polyadenylation. Fertilization is highlighted as a calcium-dependent trigger for oocyte activation. During fertilization in vertebrates, sperm-delivered phospholipase C zeta (PLCζ) is a key activator of Ca²⁺ signaling in mammals. In contrast, amphibian species such as Xenopus lack a PLCZ1 ortholog and instead appear to rely on alternative protease-mediated signaling mechanisms, including the uroplakin III–Src tyrosine kinase pathway and matrix metalloproteinase (MMP)-2 activity, to achieve egg activation. The review also addresses the molecular fate of unfertilized eggs, comparing apoptotic and necrotic mechanisms and their relevance to reproductive health. Finally, we discuss recent innovations in Xenopus-based technologies such as mRNA microinjection, genome editing, and in vitro ovulation systems, which are opening new avenues in developmental biology and translational medicine. By integrating classic findings with emerging frontiers, this review underscores the continued value of the Xenopus model in elucidating the fundamental processes of life’s origin. We conclude with perspectives on unresolved questions and future directions in oocyte and early embryonic research. Full article

Cleavage and polyadenylation (CPA) is a co-transcriptional mRNA processing mechanism that is central to mRNA and protein function. Dysregulation of CPA is widespread in cancer, promotes oncogenic programs, and affects patient outcomes. The CPA machinery is composed of multiple factors, and while prior research has investigated the impact of CPA gene expression on cancer phenotypes, the contribution of genomic alterations, such as mutations and copy number variations, remains largely unexplored. In this study, we conducted a pan-cancer analysis of genomic alterations in CPA genes. While numerous CPA genes harbor somatic mutations, these mutations do not significantly impact mRNA expression or provide prognostic value. In contrast, we found that copy number alterations in CPA genes have substantial clinical relevance. Notably, we identified the cleavage and polyadenylation specificity factor 1 (CPSF1) gene as the most frequently amplified CPA gene in cancer. While amplification of CPSF1 and MYC are co-occuring, CPSF1 amplification independently correlates with poor prognosis. We also found that CPSF1 amplification can impact 3′UTR length regardless of MYC status. Our study highlights the importance of CPSF1 as a promising prognostic factor in cancer and as a therapeutic intervention target to study in the future. Full article

Background/Objectives: Despite extensive research on hepatitis B virus (HBV), its post-transcriptional regulatory mechanisms remain incompletely characterized, particularly regarding epitranscriptomic modifications. This study aims to systematically profile the transcriptomic complexity and RNA modification landscape of HBV in hepatocellular carcinoma models. Methods: We transfected PLC/PRF/5 and Huh7 cells with the HBV 1.3-mer WT replicon plasmid, followed by qPCR measurement of viral load. Total nucleic acids extracted from transfected cells underwent nanopore direct RNA sequencing. The complete HBV transcriptome was then analyzed in two established hepatocellular carcinoma cell lines (PLC/PRF/5 and Huh7), with alternative splicing, polyadenylation, and RNA modifications identified through comprehensive bioinformatics analysis. Results: Our analysis revealed substantial transcriptomic diversity, identifying 34 distinct splice variants—including 14 previously unreported isoforms—with cell-type-specific expression patterns. Additionally, we detected 30 high-confidence RNA modification sites across HBV transcripts, with 93% (28 sites) conserved between both cellular environments. Notably, we observed significant intercellular heterogeneity in poly(A) tail length distributions. Conclusions: A comparison of the post-transcriptional processing modifications of HBV in PLC/PRF/5 and Huh7 cells reveals that the former may be better able to mimic the immune evasion mechanisms of chronic HBV infection. In contrast, the longer poly(A) tails present in Huh7 cells facilitate efficient replication, rendering these cells more amenable to the study of HBV transcription and replication mechanisms. These findings comprehensively elucidate the post-transcriptional regulatory mechanisms of hepatitis B virus in different hepatocellular carcinoma cell lines, establishing a critical benchmark for selecting appropriate experimental models in virology research. The identified transcriptomic features may provide new insights for developing antiviral strategies targeting the viral epigenome. Full article

The mammalian brain undergoes a series of orderly developmental events, including neurogenesis, neuronal migration, axon guidance, and synaptic connection. These neurodevelopmental mechanisms have traditionally been characterized through studies focused on transcriptional control; however, a growing body of evidence highlights the critical roles of co- or post-transcriptional steps like alternative splicing, alternative polyadenylation, and RNA chemical modification in orchestrating brain development. This review discusses the recent progress made toward understanding the influence of alternative mRNA processing on neurodevelopment, including three aspects: the key mRNA processing events that drive neuronal differentiation from stem/progenitor cells; the regulatory mechanisms that govern cell-type and stage-specific mRNA-processing patterns; and the neuropathological consequences of mRNA-processing dysregulation. By integrating these insights, we aim to deepen the understanding of how mRNA alternative processing influences neurodevelopment and its implications for neurological health. Full article

Platax teira is a marine fish species with both ornamental and economic value, but it faces challenges in aquaculture due to environmental stress and disease. Genetic research on P. teira has been limited due to the limitations of the partially incomplete reference genome and the lack of a complete transcriptome. In this study, we utilized PacBio SMRT sequencing to generate a full-length transcriptome for P. teira, obtaining 39,770 isoforms, including 32,265 known gene-related transcripts and 4730 novel transcripts from 3455 new genes. All novel genes were annotated, and enrichment analysis revealed significant associations between immune-related pathways, such as cAMP, MAPK, PI3K-Akt, and Wnt. We also identified 14,398 alternative splicing events, 2754 alternative polyadenylation events, 42,250 SSRs, 1569 transcription factors, and 2067 long non-coding RNAs. Additionally, protein–protein interaction (PPI) analysis of immune-related pathways predicted chemokines as key immune factors among novel genes. Domain prediction analysis highlighted the diverse functional potential of immune factors such as NLRC3, tyrosine kinase 2, and A2M in different alternative splicing events. Overall, the characterization of the full-length transcriptome dataset of P. teira lays the foundation for further studies on its genetic analysis and immune regulation. Full article

Honeybees are vital pollinators with functional differentiation as a key survival strategy. The Chinese honeybee (Apis cerana cerana) exhibits exceptional nectar foraging in complex terrains, yet how alternative splicing (AS) and polyadenylation (APA) regulate its labor division remains unclear. Here, we applied PacBio full-length transcriptome sequencing to annotate worker bee transcriptomes across three developmental stages (Ac3d, Ac10d, Ac21d), calibrating the third-generation sequencing data with second-generation sequencing to enhance transcriptome annotation accuracy. We identified 17,961 isoforms and 1922 APA genes, finding that alternative first exon was the major type of AS, while APA enhances transcriptomic diversity via dual polyadenylation sites in most genes. Functional analyses revealed AS enrichment in growth signaling (Vg6, CYP15A1) and immune pathways (PTPRR), whereas APA regulated growth signaling (Vg6), energy metabolism (Acsl1, AcceFE), and oxidative stress (PTPRR, PPO2). Validation by PCR and 3′RACE confirmed stage-specific AS/APA events in key genes. These findings significantly enhance the A. cerana cerana reference genome annotation and provide valuable insights into the mechanisms of AS and APA regulation underlying honeybee development and functional transitions. Full article