Transcriptional regulation of CCNO during the formation of multiple motile cilia.

Primary ciliary dyskinesia (PCD) is a group of genetically heterogeneous disorders characterized by clinical manifestations resulting from abnormal ciliary motility. Mutations in critical genes, such as Cyclin O (CCNO), have been associated with severe respiratory disease, though limited data are currently available. Here we show that CCNO deficient ciliated cells can only form a reduced number of fully functional centrioles that can mature into ciliated basal bodies, and their transport and anchoring to the top of the plasma membrane are abnormal. Furthermore, we observed that CCNO localizes not only in the cytoplasm but also in the nucleus during the early stages of ciliogenesis, and this dual localization persists into adulthood. Transcriptome analysis revealed downregulation of genes involved in cilia assembly and movement, along with altered transcription factors associated with ciliation upon CCNO depletion. These findings indicate that CCNO may serve as a key regulator in the transcriptional regulation of multiciliogenesis.

circRUNX2.2, highly expressed in Marek's disease tumor tissues, functions in cis to regulate parental gene RUNX2 expression.

Marek's disease (MD), an immunosuppression disease induced by Marek's disease virus (MDV), is one of the significant diseases affecting the health and productive performance of poultry. The roles of circular RNAs (circRNAs) in MD development were poorly understood. In this study, we found a circRNA derived from exon 6 of RUNX family transcription factor 2 (RUNX2) gene, named circRUNX2.2, was highly expressed in chicken tumorous spleens (TS) induced by MDV. Through fluorescence in situ hybridization and nuclear-cytoplasmic separation assay, we determined circRUNX2.2 was mainly located in the nucleus. Knockout experiments confirmed that the flanking complementary sequences (RCMs) mediated its circularization. Gain of function assay and dual luciferase reporter gene assay revealed that circRUNX2.2 could promote the expression of RUNX2 via binding with its promoter region. RNA antisense purification assay and mass spectrometry assay showed circRUNX2.2 could recruit proteins such as CHD9 protein. Knocking down CHD9 expression decreased the expression of RUNX2 gene, which confirmed the positive regulation that circRUNX2.2 on RUNX2 expression was probably facilitated via recruiting CHD9 protein. Functional experiments showed that circRUNX2.2 promoted the proliferation of the MD lymphoma-derived chicken cell line, MDCC-MSB1, which confirmed the potential oncogenic role of circRNX2.2 in tumor development. In conclusion, we found that the RUNX2-derived circRUNX2.2 can positively regulate the transcription of the parental gene RUNX2 in a cis-acting manner. The high expression of circRUNX2.2 in MD tumor tissues indicated that it might mediate MD lymphoma progression.

Integrated metabolomic and transcriptomic analysis reveals biosynthesis mechanism of flavone and caffeoylquinic acid in chrysanthemum.

BACKGROUND: Chrysanthemum morifolium 'HangBaiJu', a popular medicinal and edible plant, exerts its biological activities primarily through the presence of flavones and caffeoylquinic acids (CQAs). However, the regulatory mechanism of flavone and CQA biosynthesis in the chrysanthemum capitulum remains unclear. RESULTS: In this study, the content of flavones and CQAs during the development of chrysanthemum capitulum was determined by HPLC, revealing an accumulation pattern with higher levels at S1 and S2 and a gradual decrease at S3 to S5. Transcriptomic analysis revealed that CmPAL1/2, CmCHS1/2, CmFNS, CmHQT, and CmHCT were key structural genes in flavones and CQAs biosynthesis. Furthermore, weighted gene co-expression correlation network analysis (WGCNA), k-means clustering, correlation analysis and protein interaction prediction were carried out in this study to identify transcription factors (TFs) associated with flavone and CQA biosynthesis, including MYB, bHLH, AP2/ERF, and MADS-box families. The TFs CmERF/PTI6 and CmCMD77 were proposed to act as upstream regulators of CmMYB3 and CmbHLH143, while CmMYB3 and CmbHLH143 might form a complex to directly regulate the structural genes CmPAL1/2, CmCHS1/2, CmFNS, CmHQT, and CmHCT, thereby controlling flavone and CQA biosynthesis. CONCLUSIONS: Overall, these findings provide initial insights into the TF regulatory network underlying flavones and CQAs accumulation in the chrysanthemum capitulum, which laid a theoretical foundation for the quality improvement of C. morifolium 'HangBaiJu' and the high-quality development of the industry.

A viroid-derived small interfering RNA targets bHLH transcription factor MdPIF1 to regulate anthocyanin biosynthesis in Malus domestica.

Fruit colour is a critical determinant for the appearance quality and commercial value of apple fruits. Viroid-induced dapple symptom severely affects the fruit coloration, however, the underlying mechanism remains unknown. In this study, we identified an apple dimple fruit viroid (ADFVd)-derived small interfering RNA, named vsiR693, which targeted the mRNA coding for a bHLH transcription factor MdPIF1 (PHYTOCHROME-INTERACTING FACTOR 1) to regulate anthocyanin biosynthesis in apple. 5' RLM-RACE and artificial microRNA transient expression system proved that vsiR693 directly targeted the mRNA of MdPIF1 for cleavage. MdPIF1 positively regulated anthocyanin biosynthesis in both apple calli and fruits, and it directly bound to G-box element in the promoter of MdPAL and MdF3H, two anthocyanin biosynthetic genes, to promote their transcription. Expression of vsiR693 negatively regulated anthocyanin biosynthesis in both apple calli and fruits. Furthermore, co-expression of vsiR693 and MdPIF1 suppressed MdPIF1-promoted anthocyanin biosynthesis in apple fruits. Infiltration of ADFVd infectious clone suppressed coloration surrounding the injection sites in apple fruits, while a mutated version of ADFVd, in which the vsiR693 producing region was mutated, failed to repress fruit coloration around the injection sites. These data provide evidence that a viroid-derived small interfering RNA targets host transcription factor to regulate anthocyanin biosynthesis in apple.

scBlood: A comprehensive single-cell accessible chromatin database of blood cells.

The advent of single cell transposase-accessible chromatin sequencing (scATAC-seq) technology enables us to explore the genomic characteristics and chromatin accessibility of blood cells at the single-cell level. To fully make sense of the roles and regulatory complexities of blood cells, it is critical to collect and analyze these rapidly accumulating scATAC-seq datasets at a system level. Here, we present scBlood (https://bio.liclab.net/scBlood/), a comprehensive single-cell accessible chromatin database of blood cells. The current version of scBlood catalogs 770,907 blood cells and 452,247 non-blood cells from ∼400 high-quality scATAC-seq samples covering 30 tissues and 21 disease types. All data hosted on scBlood have undergone preprocessing from raw fastq files and multiple standards of quality control. Furthermore, we conducted comprehensive downstream analyses, including multi-sample integration analysis, cell clustering and annotation, differential chromatin accessibility analysis, functional enrichment analysis, co-accessibility analysis, gene activity score calculation, and transcription factor (TF) enrichment analysis. In summary, scBlood provides a user-friendly interface for searching, browsing, analyzing, visualizing, and downloading scATAC-seq data of interest. This platform facilitates insights into the functions and regulatory mechanisms of blood cells, as well as their involvement in blood-related diseases.

Functional characterization of sesquiterpene synthase in Mongolian medicine Syringa oblata in heartwood formation.

Lilac (Syringa oblata) is a well-known horticultural plant, and its aromatic heartwood is widely utilized in Traditional Mongolian Medicine for treating angina. However, limited research on the dynamic changes and mechanisms of aromatic substance formation during heartwood development hinders the analysis and utilization of its medicinal components. In this study, volatile metabolome analysis revealed that sesquiterpenes are the primary metabolites responsible for the aroma in heartwood, with cadinane and eremophilane types being the most prevalent. Among the identified sesquiterpene synthases, SoSTPS1-5 exhibited significantly increased expression in heartwood formation and was selected for further investigation. Molecular docking simulations predicted multiple amino acid binding sites and confirmed its ability to catalyze the formation of eremophilane, copaene, cadinane, germacrane, and elemane-type sesquiterpenes from FPP (farnesyl pyrophosphate). Co-expression and promoter analysis suggested a transcriptional regulatory network primarily involving WRKY transcription factors. Additionally, aiotic and biotic stress inducers, such as Ag+, Fusarium oxysporum, and especially MeJA, were found to activate the expression of SoSTPS1-5 and promote sesquiterpene accumulation. This study provides insights into the basis of medicinal substance formation and the potential mechanisms of sesquiterpene accumulation in lilac heartwood, laying a foundation for future research on the biosynthesis and utilization of its medicinal components.

Small RNA-regulated expression of efflux pump affects tigecycline resistance and heteroresistance in clinical isolates of Klebsiella pneumoniae.

Tigecycline and the newly Food and Drug Administration-approved tetracyclines, including eravacycline and omadacycline, are regarded as last-resort treatments for multidrug-resistant Enterobacterales. However, tigecycline resistance in Klebsiella pneumoniae has increased, especially the underlying mechanism of heteroresistance is unclear. This study aimed to elucidate the mechanisms underlying tigecycline resistance and heteroresistance in clinical K. pneumoniae isolates. A total of 153 clinical K. pneumoniae isolates were collected, and identified 15 tigecycline-resistant and three tigecycline-heteroresistant isolates using broth microdilution and population analysis profile methods, respectively. Total RNAs from K. pneumoniae ATCC13883 and the laboratory-induced tigecycline-resistant strain were extracted and sequenced on an Illumina platform. Differentially expressed genes and regulatory small RNAs (sRNAs) were analyzed and validated in clinical isolates of K. pneumoniae using quantitative real-time PCR. RNA sequencing results showed that mdtABC efflux pump genes were significantly upregulated in the tigecycline-resistant strains. Overexpression of mdtABC was observed in a clinical K. pneumoniae isolate, which increased tigecycline minimum inhibitory concentrations (MICs) and was involved in tigecycline heteroresistance. Sequencing analysis of sRNA demonstrated that candidate sRNA-120 directly interacted with the mdtABC operon and was downregulated in tigecycline-resistant strains. We generated an sRNA-120 deletion mutation strain and a complemented strain of K. pneumoniae. The sRNA-120 deletion strain displayed increased mRNA levels of mdtA, mdtB, and mdtC and an increase in MICs of tigecycline. The complemented strain of sRNA-120 restored the mRNA levels of these genes and the susceptibility to tigecycline. RNA antisense purification and parallel reaction monitoring mass spectrometry were performed to verify the interactions between sRNA-120 and mdtABC. Collectively, our study highlights that the post-transcriptional repression of mdtABC through sRNA-120 may provide an additional layer of efflux pump gene expression control, which is important for resistance and heteroresistance in clinical K. pneumoniae isolates.

FaERF2 activates two ß-1,3-glucanase genes to enhance strawberry resistance to Botrytis cinerea.

Ethylene response factor (ERF) is a class of plant-specific transcription factors that play an important role in plant growth, development, and stress response. However, the underlying mechanism of strawberry ERFs in pathogenic responses against Botrytis cinerea (B. cinerea) remains largely unclear. In this study, we isolated FaERF2, a nucleus-localized ERF transcription factor from Fragaria x ananassa. Transiently overexpressing FaERF2 in strawberry fruits significantly enhances their resistant ability to B. cinerea, while silencing FaERF2 in strawberry fruits enhances their susceptibility to B. cinerea. In addition, we found that FaERF2 could directly bind to the cis-acting element GCC box in the promoters of two ß-1,3-glucanase genes, FaBG-1 and FaBG-2, and activate their expression. Finally, both strawberry fruits transient expression followed by B. cinerea inoculation assays and recombinant protein incubation tests collectively substantiated the inhibitory effect of FaBG-1 and FaBG-2 on B. cinerea mycelium growth. These results revealed the molecular regulation mechanism of FaERF2 in response to B. cinerea and laid foundations for creating disease-resistance strawberry cultivar through genome editing approach.

The Role of the Transcriptional Coactivator BOB.1/OBF.1 in Adaptive Immunity.

BOB.1/OBF.1 is a transcriptional coactivator involved in octamer-dependent transcription. Thereby, BOB.1/OBF.1 is involved in the transcriptional regulation of genes important for lymphocyte physiology. BOB.1/OBF.1-deficient mice reveal multiple B- and T-cell developmental defects. The most prominent defect of these mice is the complete absence of germinal centers (GCs) resulting in severely impaired T-cell-dependent immune responses. In humans, BOB.1/OBF.1 is associated with several autoimmune and inflammatory diseases but also linked to liquid and solid tumors. Although its role for B-cell development is relatively well understood, its exact role for the GC reaction and T-cell biology has long been unclear. Here, the contribution of BOB.1/OBF.1 for B-cell maturation is summarized, and recent findings regarding its function in GC B- as well as in various T-cell populations are discussed. Finally, a detailed perspective on how BOB.1/OBF.1 contributes to different pathologies is provided.

Overexpression of a Grape WRKY Transcription Factor VhWRKY44 Improves the Resistance to Cold and Salt of Arabidopsis thaliana.

Plants are often exposed to biotic or abiotic stress, which can seriously impede their growth and development. In recent years, researchers have focused especially on the study of plant responses to biotic and abiotic stress. As one of the most widely planted grapevine rootstocks, 'Beta' has been extensively proven to be highly resistant to stress. However, further research is needed to understand the mechanisms of abiotic stress in 'Beta' rootstocks. In this study, we isolated and cloned a novel WRKY transcription factor, VhWRKY44, from the 'Beta' rootstock. Subcellular localization analysis revealed that VhWRKY44 was a nuclear-localized protein. Tissue-specific expression analysis indicated that VhWRKY44 had higher expression levels in grape roots and mature leaves. Further research demonstrated that the expression level of VhWRKY44 in grape roots and mature leaves was highly induced by salt and cold treatment. Compared with the control, Arabidopsis plants overexpressing VhWRKY44 showed stronger resistance to salt and cold stress. The activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly increased, and the contents of proline, malondialdehyde (MDA) and chlorophyll were changed considerably. In addition, significantly higher levels of stress-related genes were detected in the transgenic lines. The results indicated that VhWRKY44 was an important transcription factor in 'Beta' with excellent salt and cold tolerance, providing a new foundation for abiotic stress research.

Regulation of oxidative stress response and antioxidant modification in Corynebacterium glutamicum.

As an efficient and safe industrial bacterium, Corynebacterium glutamicum has extensive application in amino acid production. However, it often faces oxidative stress induced by reactive oxygen species (ROS), leading to diminished production efficiency. To enhance the robustness of C. glutamicum, numerous studies have focused on elucidating its regulatory mechanisms under various stress conditions such as heat, acid, and sulfur stress. However, a comprehensive review of its defense mechanisms against oxidative stress is needed. This review offers an in-depth overview of the mechanisms C. glutamicum employs to manage oxidative stress. It covers both enzymatic and non-enzymatic systems, including antioxidant enzymes, regulatory protein families, sigma factors involved in transcription, and physiological redox reduction pathways. This review provides insights for advancing research on the antioxidant mechanisms of C. glutamicum and sheds light on its potential applications in industrial production.

Post-transcriptional regulation of DEAD-box RNA helicases in hematopoietic malignancies.

Hematopoiesis represents a meticulously regulated and dynamic biological process. Genetic aberrations affecting blood cells, induced by various factors, frequently give rise to hematological tumors. These instances are often accompanied by a multitude of abnormal post-transcriptional regulatory events, including RNA alternative splicing, RNA localization, RNA degradation, and storage. Notably, post-transcriptional regulation plays a pivotal role in preserving hematopoietic homeostasis. The DEAD-Box RNA helicase genes emerge as crucial post-transcriptional regulatory factors, intricately involved in sustaining normal hematopoiesis through diverse mechanisms such as RNA alternative splicing, RNA modification, and ribosome assembly. This review consolidates the existing knowledge on the role of DEAD-box RNA helicases in regulating normal hematopoiesis and underscores the pathogenicity of mutant DEAD-Box RNA helicases in malignant hematopoiesis. Emphasis is placed on elucidating both the positive and negative contributions of DEAD-box RNA helicases within the hematopoietic system.

Global changes of miRNA expression indicates an increased reprogramming efficiency of induced mammary epithelial cells by repression of miR-222-3p in fibroblasts.

Background: Our previous studies have successfully reported the reprogramming of fibroblasts into induced mammary epithelial cells (iMECs). However, the regulatory relationships and functional roles of MicroRNAs (miRNAs) in the progression of fibroblasts achieving the cell fate of iMECs are insufficiently understood. Methods: First, we performed pre-and post-induction miRNAs sequencing analysis by using high-throughput sequencing. Following that, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment studies were used to determine the primary roles of the significantly distinct miRNAs and targeted genes. Finally, the effect of miR-222-3p on iMECs fate reprogramming in vitro by transfecting. Results: As a result goat ear fibroblasts (GEFs) reprogramming into iMECs activates a regulatory program, involving 79 differentially expressed miRNAs. Besides, the programming process involved changes in multiple signaling pathways such as adherens junction, TGF-ß signaling pathway, GnRH secretion and the prolactin signaling pathway, etc. Furthermore, it was discovered that the expression of miR-222-3p downregulation by miR-222-3p inhibitor significantly increase the reprogramming efficiency and promoted lipid accumulation of iMECs.

Chlamydomonas cells transition through distinct Fe nutrition stages within 48 h of transfer to Fe-free medium.

Low iron (Fe) bioavailability can limit the biosynthesis of Fe-containing proteins, which are especially abundant in photosynthetic organisms, thus negatively affecting global primary productivity. Understanding cellular coping mechanisms under Fe limitation is therefore of great interest. We surveyed the temporal responses of Chlamydomonas (Chlamydomonas reinhardtii) cells transitioning from an Fe-rich to an Fe-free medium to document their short and long-term adjustments. While slower growth, chlorosis and lower photosynthetic parameters are evident only after one or more days in Fe-free medium, the abundance of some transcripts, such as those for genes encoding transporters and enzymes involved in Fe assimilation, change within minutes, before changes in intracellular Fe content are noticeable, suggestive of a sensitive mechanism for sensing Fe. Promoter reporter constructs indicate a transcriptional component to this immediate primary response. With acetate provided as a source of reduced carbon, transcripts encoding respiratory components are maintained relative to transcripts encoding components of photosynthesis and tetrapyrrole biosynthesis, indicating metabolic prioritization of respiration over photosynthesis. In contrast to the loss of chlorophyll, carotenoid content is maintained under Fe limitation despite a decrease in the transcripts for carotenoid biosynthesis genes, indicating carotenoid stability. These changes occur more slowly, only after the intracellular Fe quota responds, indicating a phased response in Chlamydomonas, involving both primary and secondary responses during acclimation to poor Fe nutrition.

Molecular Mechanisms of Plant Responses to Copper: From Deficiency to Excess.

Copper (Cu) is an essential nutrient for plant growth and development. This metal serves as a constituent element or enzyme cofactor that participates in many biochemical pathways and plays a key role in photosynthesis, respiration, ethylene sensing, and antioxidant systems. The physiological significance of Cu uptake and compartmentalization in plants has been underestimated, despite the importance of Cu in cellular metabolic processes. As a micronutrient, Cu has low cellular requirements in plants. However, its bioavailability may be significantly reduced in alkaline or organic matter-rich soils. Cu deficiency is a severe and widespread nutritional disorder that affects plants. In contrast, excessive levels of available Cu in soil can inhibit plant photosynthesis and induce cellular oxidative stress. This can affect plant productivity and potentially pose serious health risks to humans via bioaccumulation in the food chain. Plants have evolved mechanisms to strictly regulate Cu uptake, transport, and cellular homeostasis during long-term environmental adaptation. This review provides a comprehensive overview of the diverse functions of Cu chelators, chaperones, and transporters involved in Cu homeostasis and their regulatory mechanisms in plant responses to varying Cu availability conditions. Finally, we identified that future research needs to enhance our understanding of the mechanisms regulating Cu deficiency or stress in plants. This will pave the way for improving the Cu utilization efficiency and/or Cu tolerance of crops grown in alkaline or Cu-contaminated soils.

Huaier inhibits cholangiocarcinoma cells through the twist1/FBP1/Wnt/ß-catenin axis.

BACKGROUND: Although Huaier granules can be used as prospective anti-cholangiocarcinoma drugs, the mechanism of action of Huaier granules in cholangiocarcinoma is not clear. The anti-cholangiocarcinoma effect of Huaier granules was validated in cell line research. In vitro experiments were conducted to investigate the signalling pathways affected by Huaier in CCA cells. METHODS AND RESULTS: Real-time quantitative PCR (RT‒qPCR) and Western blot analysis were performed to analyse gene expression in CCA cells. MTT assays, scratch tests, and Transwell assays were used to explore the effects on the proliferation and metastasis of CCA cells. Chromatin immunoprecipitation assays were performed to reveal the potential underlying mechanisms involved. Twist1 was upregulated in human CCA tissues. In addition, its expression levels were negatively related to FBP1 expression levels. Mechanistically, Twist1 can bind to the region of the FBP1 promoter to reduce its expression. Huaier plays an indispensable role in suppressing Twist1 expression to inhibit the Twist1/FBP1/Wnt/ß-catenin axis. Then, we verified the effect of Huaier in vitro. CONCLUSIONS: These findings suggested that Huaier granules were capable of inhibiting CCA development through regulating the Twist1/FBP1/Wnt/ß-catenin signalling axis and provided a novel orientation for the development of novel anti-CCA drugs.

Suppression of interferon α and γ response by Huwe1-mediated Miz1 degradation promotes SARS-CoV-2 replication.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been demonstrated to limit the host interferon response; however, the underlying mechanism remains unclear. Here, we found that SARS-CoV-2 infection upregulated the E3 ubiquitin ligase Huwe1, which in turn facilitated the degradation of the transcription factor Miz1. The degradation of Miz1 hampered interferon alpha and gamma responses, consequently fostering viral replication and impeding viral clearance. Conversely, silencing or inhibiting Huwe1 enhanced the interferon responses, effectively curbing viral replication. Consistently, overexpressing Miz1 augmented the interferon responses and limited viral replication, whereas silencing Miz1 had the opposite effect. Targeting Huwe1 or overexpressing Miz1 elicited transcriptomic alterations characterized by enriched functions associated with bolstered antiviral response and diminished virus replication. Further study revealed Miz1 exerted epigenetic control over the transcription of specific interferon signaling molecules, which acted as common upstream regulators responsible for the observed transcriptomic changes following Huwe1 or Miz1 targeting. These findings underscore the critical role of the Huwe1-Miz1 axis in governing the host antiviral response, with its dysregulation contributing to the impaired interferon response observed during COVID-19.

CRISPR-Cas9-mediated deletion enhancer of MECOM play a tumor suppressor role in ovarian cancer.

MDS1 and EVI1 complex locus (MECOM), a transcription factor encoding several variants, has been implicated in progression of ovarian cancer. The function of regulatory regions in regulating MECOM expression in ovarian cancer is not fully understood. In this study, MECOM expression was evaluated in ovarian cancer cell lines treated with bromodomain and extraterminal (BET) inhibitor JQ-1. Oncogenic phenotypes were assayed using assays of CCK-8, colony formation, wound-healing and transwell. Oncogenic phenotypes were estimated in stable sgRNA-transfected OVCAR3 cell lines. Xenograft mouse model was assayed via subcutaneous injection of enhancer-deleted OVCAR3 cell lines. The results displayed that expression of MECOM is downregulated in cell lines treated with JQ-1. Data from published ChIP-sequencing (H3K27Ac) in 3 ovarian cancer cell lines displayed a potential enhancer around the first exon. mRNA and protein expression were downregulated in OVCAR3 cells after deletion of the MECOM enhancer. Similarly, oncogenic phenotypes both in cells and in the xenograft mouse model were significantly attenuated. This study demonstrates that JQ-1 can inhibit the expression of MECOM and tumorigenesis. Deletion of the enhancer activity of MECOM has an indispensable role in inhibiting ovarian cancer progress, which sheds light on a promising opportunity for ovarian cancer treatment through the application of this non-coding DNA deletion.

AtSNU13 modulates pre-mRNA splicing of RBOHD and ALD1 to regulate plant immunity.

Pre-mRNA splicing is a significant step for post-transcriptional modifications and functions in a wide range of physiological processes in plants. Human NHP2L binds to U4 snRNA during spliceosome assembly; it is involved in RNA splicing and mediates the development of human tumors. However, no ortholog has yet been identified in plants. Therefore, we report At4g12600 encoding the ortholog NHP2L protein, and AtSNU13 associates with the component of the spliceosome complex; the atsnu13 mutant showed compromised resistance in disease resistance, indicating that AtSNU13 is a positive regulator of plant immunity. Compared to wild-type plants, the atsnu13 mutation resulted in altered splicing patterns for defense-related genes and decreased expression of defense-related genes, such as RBOHD and ALD1. Further investigation shows that AtSNU13 promotes the interaction between U4/U6.U5 tri-snRNP-specific 27 K and the motif in target mRNAs to regulate the RNA splicing. Our study highlights the role of AtSNU13 in regulating plant immunity by affecting the pre-mRNA splicing of defense-related genes.