YTHDC1 mediates nuclear export of N6-methyladenosine methylated mRNAs

SARS-CoV-2 and HCoV-OC43 regulate host m6A modification via activation of the mTORC1 signalling pathway to facilitate viral replication

N6-methyladenosine (m6A) is the most prevalent post-transcriptional modification in eukaryotic RNA and is also present in various viral RNAs, where it plays a crucial role in regulating the viral life cycle. However, the molecular mechanisms through which viruses regulate host RNA m6A methylation are not fully understood. In this study, we reveal that SARS-CoV-2 and HCoV-OC43 infection enhance host m6A modification by activating the mTORC1 signalling pathway. Specifically, the viral non-structural protein nsp14 upregulates the expression of S-adenosylmethionine synthase MAT2A in an mTORC1-dependent manner. This mTORC1-MAT2A axis subsequently stimulates the synthesis of S-adenosylmethionine (SAM). The increase of SAM then enhances the m6A methylation of host RNA and facilitates viral replication. Our findings uncover a molecular mechanism by which viruses regulate host m6A methylation and provide insights into how SARS-CoV-2 hijacks host cellular epitranscriptomic modifications to promote its replication.

Coupling mechanisms coordinating mRNA translation with stages of the mRNA lifecycle

Gene expression involves a series of consequential processes, beginning with mRNA synthesis and culminating in translation. Traditionally studied as a linear sequence of events, recent findings challenge this perspective, revealing coupling mechanisms that coordinate key steps of gene expression, even when spatially and temporally distant. In this review, we focus on translation, the final stage of gene expression, and examine its coupling with key stages of mRNA metabolism: synthesis, processing, export, and decay. For each of these processes, we provide an overview of known instances of coupling with translation. Furthermore, we discuss the role of high-throughput technologies in uncovering these intricate interactions on a genome-wide scale. Finally, we highlight key challenges and propose future directions to advance our understanding of how coupling mechanisms orchestrate robust and adaptable gene expression programs.

Demethylase FTO in the cerebrospinal fluid-contacting nucleus of mice contributes to neuropathic pain via mediating m6A demethylation of P2rx4 mRNA

N6-methyladenosine (m6A) modification plays a crucial role in pain regulation by modulating pain-related gene expression. The cerebrospinal fluid-contacting nucleus (CSF-contacting nucleus) is closely associated with pain, and downregulation of P2X4 receptor (P2X4R) expression in this region alleviates hyperalgesia. However, the relationship between m6A modification and P2X4R in CSF-contacting nucleus remains unclear. This study aims to investigate the role and potential mechanisms of the m6A demethylase fat mass and obesity-associated protein (FTO) and P2X4R in neuropathic pain (NP) induced by spared nerve injury (SNI) in male mice. We observed decreased m6A levels and upregulated FTO expression in the CSF-contacting nucleus of SNI mice. FTO was primarily expressed in neurons of the CSF-contacting nucleus, with symmetrical distribution across its bilateral regions. In CSF-contacting nucleus, FTO overexpression reduced m6A methylation and promoted pain, while FTO inhibition increased m6A levels and alleviated pain hypersensitivity. The administration of the FTO inhibitor meclofenamic acid (MA) into CSF-contacting nucleus alleviated pain. FTO regulated the expression of P2rx4 mRNA and protein in CSF-contacting nucleus. Furthermore, P2rx4 mRNA is a downstream target of FTO-mediated m6A demethylation. In summary, the m6A demethylase FTO contributes to NP by upregulating the expression of P2rx4 mRNA and protein through mediating m6A demethylation of P2rx4 mRNA. Therefore, the m6A demethylase FTO in CSF-contacting nucleus may represent a novel therapeutic target for NP.

Decoding intricate interactions between m6A modification with mRNAs and non-coding RNAs in cervical cancer: Molecular mechanisms and clinical implications

N6-methyladenosine (m6A) methylation is the most prevalent RNA modification that is regulated by three regulatory factors: "writers", "erasers" and "readers". m6A modification regulates RNA stability and other mechanisms, including translation, cleavage, and degradation. Current research has demonstrated that m6A methylation is involved in the regulation of occurrence and development of cancers by controlling the expression of cancer-related genes. This review summarizes the role of m6A modification on messenger RNAs (mRNAs) and non-coding RNAs (ncRNAs) in cervical cancer (CC). We highlight the dual role of m6A regulatory factors, which act as oncogenes or tumor suppressors depending on the cellular context and downstream targets. Additionally, we examine how ncRNAs reciprocally regulate m6A modification in two ways: by guiding the deposition or removal of m6A modifications on RNA targets, and by modulating the expression of m6A regulatory factors. These interactions further contribute to tumor progression. Furthermore, the therapeutic potential of targeting m6A modification has been emphasized in CC. Moreover, recent advances in small-molecule inhibitors targeting m6A regulators and RNA-based therapies which may offer new treatment strategies have been summarized. Finally, we discuss the current challenges in m6A modification research and provide suggestions for future research directions. This review aims to deepen the understanding of m6A modification in CC and contribute to the development of targeted and personalized treatment strategies.

An inflammation-associated lncRNA induces neuronal damage via mitochondrial dysfunction

Immune disease-associated non-coding SNPs, which often locate in tissue-specific regulatory elements, are emerging as key factors in gene regulation. Among these elements, long non-coding RNAs (lncRNAs) participate in many cellular processes, and their characteristics make these molecules appealing therapeutic targets. In this study, we have studied lncRNA LOC339803 in the context of neuronal cells, which is located in autoimmunity-associated region 2p15 and recently described to have a proinflammatory role in intestinal disorders. Using human brain samples and a wide variety of in vitro techniques, we have showed a differential function of this lncRNA in neuronal cells. We have further demonstrated the role of LOC339803 in maintaining hexokinase 2 (HK2) levels and thus mitochondrial integrity, partially explaining the implication of the lncRNA in multiple sclerosis (MS) pathogenesis. Our results show the importance of cell-type-specific studies in the case of regulatory lncRNAs. We present LOC339803 as a candidate for further studies as a mitochondrial dysfunction marker or possible therapeutic target in neurodegeneration.

m6A RNA methylation-mediated control of global APC expression is required for local translation of β-actin and axon development

The spatial regulation of mRNAs in neurons, including their localization and translation, is controlled by RNA-binding proteins and is critical for neuronal development. In this study, we present evidence that the multifunctional RNA-binding protein adenomatous polyposis coli (APC) is encoded by an mRNA modified with N6-methyladenosine (m6A). This modification facilitates the translation of APC in neuronal somata via YTH domain-containing family (YTHDF) m6A reader proteins. Disrupted APC expression, caused by reduced expression of the m6A writer METTL14 or reader YTHDF1, or by overexpression of METTL14 mutants carrying human missense mutations linked to autism and schizophrenia, impairs the transport and local translation of APC-regulated target mRNA β-actin in axons and growth cones. Such disruptions consequently hinder axon development both in vitro and in vivo. These findings reveal a mechanism by which m6A-regulated global expression of the RNA-binding protein APC governs axonal mRNA translation and development.

YTHDC1 promotes postnatal brown adipose tissue development and thermogenesis by stabilizing PPARγ

Brown adipose tissue (BAT) plays a vital role in non-shivering thermogenesis and energy metabolism and is influenced by factors like environmental temperature, ageing, and obesity. However, the molecular mechanisms behind BAT development and thermogenesis are not fully understood. Our study identifies the m6A reader protein YTHDC1 as a crucial regulator of postnatal interscapular BAT development and energy metabolism in mice. YTHDC1 directly interacts with PPARγ through its intrinsically disordered region (IDR), thus protecting PPARγ from binding the E3 ubiquitin ligase ARIH2, and preventing its ubiquitin-mediated proteasomal degradation. Specifically, the ARIH2 RING2 domain is essential for PPARγ degradation, while PPARγ's A/B domain is necessary for their interaction. Deletion of Ythdc1 in BAT increases PPARγ degradation, impairing interscapular BAT development, thermogenesis, and overall energy expenditure. These findings reveal a novel mechanism by which YTHDC1 regulates BAT development and energy homeostasis independently of its m6A recognition function.

Nanopore direct RNA sequencing of human transcriptomes reveals the complexity of mRNA modifications and crosstalk between regulatory features

The identification and functional characterization of chemical modifications on an mRNA molecule, in particular N6-methyladenosine (m6A) modification, significantly broadened our understanding of RNA function and regulation. While interactions between RNA modifications and other RNA features have been proposed, direct evidence showing correlation is limited. Here, using Oxford Nanopore long-read direct RNA sequencing (dRNA-seq), we simultaneously interrogate the transcriptome and epitranscriptome of a human leukemia cell line to investigate the correlation between m6A modifications, mRNA abundance, mRNA stability, polyadenylation (poly(A)) tail length, and alternative splicing. High-quality dRNA-seq is important for unbiased and large-scale correlative analyses. Global assessments indicated a negative association between poly(A) tail length and mRNA abundance while uncovering pathway-specific responses upon depletion of the m6A-forming enzyme METTL3. Overall, our study presented a rich dRNA-seq data resource that has been validated and can be further exploited to inquire into the complexity of RNA modifications and potential interplays between RNA regulatory elements.

From bone marrow mesenchymal stem cells to diseases: the crucial role of m6A methylation in orthopedics

Elucidating the molecular mechanisms underlying orthopedic diseases is crucial for guiding therapeutic strategies and developing innovative interventions. N6-methyladenosine (m6A)-an epitranscriptomic modification-has emerged as a key regulator of cellular fate and tissue homeostasis. Specifically, m6A plays a pivotal role in several RNA biological processes such as precursor RNA splicing, 3'-end processing, nuclear export, translation, and stability. Recent advancements indicate that m6A methylation regulates stem cell proliferation and osteogenic differentiation by modulating various signaling pathways. Extensive research has shown that abnormalities in m6A methylation contribute significantly to the onset and progression of various orthopedic diseases such as osteoporosis (OP), osteoarthritis (OA), rheumatoid arthritis (RA), and bone tumors. This review aims to summarize the key proteases involved in m6A methylation and their functions. The detailed mechanisms by which m6A methylation regulates osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) through direct and indirect ways are also discussed, with a focus on specific molecular pathways. Finally, this review analyzes the roles and mechanisms of m6A modification in the development and progression of multiple orthopedic diseases, offering a comprehensive understanding of the pathophysiology of these conditions and proposing new directions and molecular targets for innovative treatment strategies.

Recent Advance in Sensitive Detection of Demethylase FTO

Methylation modification is a critical regulatory mechanism in epigenetics and plays a significant role in various biological processes. N6-methyladenosine (m6A) is the most common modification found in RNA. The fat mass and obesity-associated protein (FTO) facilitate the demethylation of m6A in RNA, and its abnormal expression is closely linked to the development of several diseases. As a result, FTO has the potential to serve as an important biomarker for clinical disease diagnosis. Despite its significance, there has been a lack of comprehensive reviews addressing advancements in detection methods for the demethylase FTO. This review provides an overview of the progress in FTO detection methods, ranging from traditional approaches to innovative techniques, with a particular emphasis on recently reported advancements. These novel detection methods can be categorized into strategies based on enzymes, functional nucleic acids (FNA), and conformational changes. We summarize the principles and applications of these detection methods and discuss the current challenges and prospects in this field.

Mechanism of N6-Methyladenosine Modification in the Pathogenesis of Depression

N6-methyladenosine (m6A) is one of the most common post-transcriptional RNA modifications, which plays a critical role in various bioprocesses such as immunological processes, stress response, cell self-renewal, and proliferation. The abnormal expression of m6A-related proteins may occur in the central nervous system, affecting neurogenesis, synapse formation, brain development, learning and memory, etc. Accumulating evidence is emerging that dysregulation of m6A contributes to the initiation and progression of psychiatric disorders including depression. Until now, the specific pathogenesis of depression has not been comprehensively clarified, and further investigations are warranted. Stress, inflammation, neurogenesis, and synaptic plasticity have been implicated as possible pathophysiological mechanisms underlying depression, in which m6A is extensively involved. Considering the extensive connections between depression and neurofunction and the critical role of m6A in regulating neurological function, it has been increasingly proposed that m6A may have an important role in the pathogenesis of depression; however, the results and the specific molecular mechanisms of how m6A methylation is involved in major depressive disorder (MDD) were varied and not fully understood. In this review, we describe the underlying molecular mechanisms between m6A and depression from several aspects including inflammation, stress, neuroplasticity including neurogenesis, and brain structure, which contain the interactions of m6A with cytokines, the HPA axis, BDNF, and other biological molecules or mechanisms in detail. Finally, we summarized the perspectives for the improved understanding of the pathogenesis of depression and the development of more effective treatment approaches for this disorder.

The N6-methyladenosine reader ECT1 regulates seed germination via gibberellic acid- and phytochrome B-mediated signaling

Seed germination, a pivotal stage in plant growth, is governed by phytohormones such as gibberellic acid (GA) and influenced by phytochromes, which are key photoreceptors in plants. The N6-methyladenosine (m6A) RNA modification is fundamental to plant growth and development. However, the molecular mechanisms underlying the regulation of PHYTOCHROME B (phyB) and the function of m6A signaling in GA-mediated seed germination remain elusive. Here, we discovered EVOLUTIONARILY CONSERVED C-TERMINAL REGION 1 (ECT1) as an m6A reader protein that directly binds to m6A and forms homodimers to enhance its stability in Arabidopsis (Arabidopsis thaliana). We observed that the ect1-1 mutant exhibits attenuated GA3 responsiveness in seed germination. Restoration of ECT1 function in ect1-1 confirmed the role of ECT1 in promoting seed germination. Our findings indicate that ECT1 promotes seed germination by destabilizing m6A-modified REPRESSOR OF GA1-3 1 (RGA1), a key inhibitor of GA-mediated seed germination. Moreover, ECT1 establishes a regulatory circuit with DOF AFFECTING GERMINATION 2 (DAG2), another regulator of GA-mediated seed germination. DAG2 directly binds to the ECT1 promoter and controls its transcription, and ECT1 modulates DAG2 mRNA stability through m6A binding. Furthermore, we identified PHYB as a common downstream target of DAG2 and ECT1. ECT1 binds directly to m6A-modified PHYB and influences its stability, and DAG2 binds to the PHYB promoter to regulate its transcription. Our findings demonstrate that ECT1 fine-tunes m6A-regulated seed germination via complex and multifaceted molecular mechanisms, particularly through interactions with GA and phyB, broadening our understanding of m6A-regulated processes in Arabidopsis.

Epigenetic regulation in oogenesis and fetal development: insights into m6A modifications

The unique physiological structure of women has led to a variety of diseases that have attracted the attention of many people in recent years. Disturbances in the reproductive system microenvironment lead to the progression of various female tumours and pregnancy disorders. Numerous studies have shown that epigenetic modifications crucially influence both oogenesis and foetal development. m6A, a modification at the mRNA level, consists of three parts, namely, writers, erasers, and readers, which are involved in several biological functions, such as the nucleation and stabilisation of mRNAs, thereby regulating the development of reproductive system diseases. In this manuscript, we delineate the constituents of m6A, their biological roles, and advancements in understanding m6A within the maternal-foetal immunological context. In addition, we summarise the mechanism of m6A in gynaecological diseases and provide a new perspective for targeting m6A to delay the progression of reproductive system diseases in clinical practice.

The regulatory role of m6A in cancer metastasis

Metastasis remains a primary cause of cancer-related mortality, with its intricate mechanisms continuing to be uncovered through advancing research. Among the various regulatory processes involved, RNA modification has emerged as a critical epitranscriptomic mechanism influencing cancer metastasis. N6-methyladenosine (m6A), recognized as one of the most prevalent and functionally significant RNA modifications, plays a central role in the regulation of RNA metabolism. In this review, we explore the multifaceted role of m6A in the different stages of cancer metastasis, including epithelial-mesenchymal transition, invasion, migration, and colonization. In addition to summarizing the current state of our understanding, we offer insights into how m6A modifications modulate key oncogenic pathways, highlighting the implications of recent discoveries for therapeutic interventions. Furthermore, we critically assess the limitations of previous studies and propose areas for future research, including the potential for targeting m6A as a novel approach in anti-metastatic therapies. Our analysis provides a comprehensive understanding of the regulatory landscape of m6A in metastasis, offering directions for continued exploration in this rapidly evolving field.

MdDSK2a-Like-MdMTA Module Functions in Apple Cold Response via Regulating ROS Detoxification and Cell Wall Deposition

N6-methyladenosine (m6A) is the most abundant internal RNA modification in eukaryotic cells. Although the importance of its roles in mRNA metabolism, plant development, and stress responses has been well documented, regulation of its machinery is largely unknown in plants. Here, it is reported that MdMTA positively regulates cold tolerance. Combining MeRIP-seq and RNA-seq, it is found that MdMTA regulates the m6A and expression levels of cold-responsive genes under cold stress, including those involved in reactive oxygen species (ROS) detoxification and cell wall deposition. Further analysis reveals that MdMTA promotes ROS scavenging and the deposition of cellulose and hemicellulose by regulating the mRNA stability of the relevant genes under cold conditions. MdDSK2a-like, a ubiquitin receptor protein, mediates MdMTA degradation by the 26S ubiquitin-dependent proteasome and autophagy pathways. MdDSK2a-like negatively regulates cold tolerance by reducing the m6A levels of MdMTA target genes. Consistently, MdDSK2a-like inhibits ROS scavenging and the deposition of cellulose and hemicellulose under cold conditions. Genetic dissection shows that MdDSK2a-like acts upstream of MdMTA in cold response. The results not only reveal the degradation of MdMTA, but also illustrate the molecular mechanism of the MdDSK2a-like-MdMTA module in m6A modification and cold response.

Trametinib ameliorated Adriamycin-induced podocyte injury by inhibiting METTL3 modified m6A RCAN1 RNA methylation

N6-methyladenosine (m6A) plays a crucial role in kidney diseases. Methyltransferase-like 3 (METTL3) as a key m6A writer can be regulated by trametinib. However, the epigenetic regulation of trametinib in focal segmental glomerulosclerosis (FSGS) remains unclear. We investigated whether trametinib protects podocytes by modulating METTL3-methylated target RNAs. Regulator of calcineurin 1 (RCAN1) was predicted as a target binding RNA of METTL3 by THEW database. Immunostaining of METTL3 and RCAN1 with podocyte marker Wilm's tumor-1 (WT-1) confirmed their localization within podocytes in renal biopsy from FSGS patients. Transfection METTL3 to human podocytes reduced WT-1, synaptopodin (SYNPO), and RCAN1 protein levels. Total m6A, m6A methylated RNA of RCAN1 increased and total RCAN1 mRNA decreased. Inhibition of METTL3 using siRNA or trametinib reversed these changes and attenuated the ADR-induced downregulation of WT-1 and SYNPO in vitro. In ADR-induced FSGS mice, trametinib ameliorated proteinuria, hypoalbuminemia, renal dysfunction, glomerulosclerosis and podocyte foot process effacement. Additionally, trametinib preserved podocyte function assessed by WT-1 and SYNPO as well as delayed renal fibrosis assessed by α-smooth muscle actin and fibronectin. Consistent with results in vitro, trametinib also decreased the ADR-induced upregulation of METTL3 and reversed the changed levels of total m6A, m6A methylated Rcan1 and total Rcan1 in FSGS mice. In conclusion, trametinib may serve as a renal protective agent for FSGS by regulating METTL3-dependent RCAN1 methylation levels.

Pathological α-synuclein dysregulates epitranscriptomic writer METTL3 to drive neuroinflammation in microglia

Recent reports suggest dysregulation of the N6-methyladenosine (m6A) RNA modification may contribute to the pathology of neurodegenerative diseases. Herein, we show the m6A methyltransferase complex including METTL3-the catalytic component of the nuclear-localized complex-is robustly upregulated in human microglia and astrocytes exposed to αSynf and Mn. Subcellular localization studies reveal METTL3 was predominantly cytoplasmic following Mn insult but remained nuclear following αSynf stimulation in activated microglia. Functional analysis revealed METTL3 and downstream m6A readers, including YTHDF2 and IGF2BP1-3, may regulate the proinflammatory secretome of activated microglia. Notably, methyltransferase activity and m6A abundance were significantly increased following Mn and αSynf treatment. METTL3 in Mn and αSynfin vivo models of neuroinflammation, along with human postmortem tissues from Alzheimer's disease (AD), Parkinson's disease (PD), and dementia with Lewy bodies (DLB) patients, was significantly upregulated. This was further confirmed by single-cell RNA sequencing (scRNA-seq) analysis. Overall, we demonstrate the m6A writer METTL3 may function as a major regulator of chronic neuroinflammation in synucleinopathies.

Regulatory mechanisms of m6A RNA methylation in esophageal cancer: a comprehensive review

Esophageal cancer is an aggressively malignant neoplasm characterized by a high mortality rate. Frequently diagnosed at an advanced stage, it presents challenges for optimal therapeutic intervention due to its non-specific symptoms, resulting in lost opportunities for effective treatment, such as surgery, radiotherapy, chemotherapy and target therapy. The N6-methyladenosine (m6A) modification represents the most critical post-transcriptional modification of eukaryotic messenger RNA (mRNA). The reversible m6A modification is mediated by three regulatory factors: m6A methyltransferases, demethylating enzymes, and m6A recognition proteins. These components identify and bind to specific RNA methylation sites, thereby modulating essential biological functions such as RNA processing, nuclear export, stability, translation and degradation, which significantly influence tumorigenesis, invasion, and metastasis. Given the importance of m6A modification, this paper offers a comprehensive examination of the regulatory mechanisms, biological functions, and future therapeutic implications of m6A RNA methylation in the context of esophageal cancer.

High-glucose-associated YTHDC1 lactylation reduces the sensitivity of bladder cancer to enfortumab vedotin therapy

Hyperglycemia is a recognized risk factor for bladder cancer (BC). Enfortumab vedotin (EV), the first NECTIN4-targeting antibody-drug conjugate, demonstrates promising clinical efficacy in patients with advanced BC. In this study, we show that EV treatment is less effective in BC patients with diabetes than in those with normoglycemia. The subsequent in vitro and in vivo experiments indicate that high glucose decreases the sensitivity of BC cells to EV. Mechanistically, lactate overproduction associated with high glucose promotes AARS1-mediated YTHDC1 lactylation and enhances RNF183-mediated YTHDC1 ubiquitination. Downregulated YTHDC1 reduces JUND mRNA stability in an m6A-dependent manner, subsequently decreasing NECTIN4 expression and EV responsiveness. Our study identifies a high-glucose-associated lactate-AARS1-YTHDC1-JUND-NECTIN4 axis that affects EV sensitivity in BC. Targeting this axis with JUND activators or β-alanine may offer therapeutic strategies to enhance the sensitivity of BC cells to EV.

METTL3-mediated m6A modification in sepsis: current evidence and future perspectives

Sepsis, a severe systemic inflammatory condition triggered by infection, is associated with high morbidity and mortality worldwide. While medical diagnosis and treatment have advanced in recent years, a specific therapy remains unavailable. Recently, significant progress has been made in studying the epigenetic RNA modification N6-methyladenosine (m6A) and its core methyltransferase METTL3. The role of m6A in sepsis has also been increasingly elucidated. This review aims to explore the pathological mechanisms of sepsis and its relationship with m6A, focusing on the role of the key m6A writer, METTL3, in sepsis.

YTHDC1 phase separation drives the nuclear export of m6A-modified lncNONMMUT062668.2 through the transport complex SRSF3-ALYREF-XPO5 to aggravate pulmonary fibrosis

Fibroblast-to-myofibroblast differentiation is the main cytopathologic characteristic of pulmonary fibrosis. However, its underlying molecular mechanism remains poorly understood. This study elucidated that the nuclear export of lncNONMMUT062668.2 (lnc668) exacerbated pulmonary fibrosis by activating fibroblast-to-myofibroblast differentiation. Mechanistic research revealed that histone H3K9 lactylation in the promoter region of the N6-methyladenosine (m6A) writer METTL3 was enriched to enhance METTL3 transcription, leading to the lnc668 m6A modification. Meanwhile, the m6A reader YTHDC1 recognized m6A-modified lnc668 and elevated the METTL3-mediated lnc668 modification. Subsequently, phase-separating YTHDC1 promoted the nuclear export of m6A-modified lnc668. In this process, the phase-separating YTHDC1 formed a nuclear pore complex with serine/arginine-rich splicing factor 3, Aly/REF export factor, and exportin-5 to assist the translocation of m6A-modified lnc668 from nucleus to cytoplasm. After nuclear export, lnc668 facilitated the translation and stability of its host gene phosphatidylinositol-binding clathrin assembly protein to activate fibroblast-to-myofibroblast differentiation, leading to the aggravation of pulmonary fibrosis, which also depended on YTHDC1 phase separation. This study first clarified that YTHDC1 phase separation is crucial for the m6A modification, nuclear export, and profibrotic role of lnc668 in exacerbating pulmonary fibrosis. These findings provide new insights into the nuclear export of cytoplasmic lncRNAs and identified potential targets for pulmonary fibrosis therapy.

Deletion of Tfap2a in hepatocytes and macrophages promotes the progression of hepatocellular carcinoma by regulating SREBP1/FASN/ACC pathway and anti-inflammatory effect of IL10

The transcription factor AP-2α plays a crucial role in the control of tumor development and progression, and suppresses the proliferation and migration of hepatocellular carcinoma (HCC). However, the detailed function and mechanisms of AP-2α in the pathogenesis of HCC are still elusive. In the current study, we investigated the role of AP-2α regulation in liver injury-mediated HCC development. Downregulation of Tfap2a expression was found in the livers of DEN/CCl4-induced fibrosis and HCC mouse model. Hepatocyte (Alb-Cre), hepatic stellate cell (HSC) (Lrat-Cre) and macrophage (LysM-Cre) specific Tfap2a knockout mice were generated, respectively. Conditional knockout of Tfap2a was able to promote hepatic steatosis in Tfap2aΔHep and Tfap2aΔMΦ mice, but not in Tfap2aΔHSC mice fed with normal chow. Tfap2aΔHep and Tfap2aΔMΦ mice treated with DEN/CCl4 for 6 months increased tumor burden compared to Tfap2a flox controls. Tfap2a-deleted macrophages or hepatocytes could enhance lipid droplet (LD) accumulation in hepatocytes. Mechanistically, AP-2α binds to the promoter regions of SREBP1/ACC/FASN and inhibits hepatic lipid de novo synthesis. Deletion of Tfap2a in macrophages enhances polarization of M1 macrophages with increased iNOS expression but decreased CD206 expression, which resulted in increased pro-inflammatory cytokines and decreased anti-inflammatory factors, especially the hepatoprotective factor IL-10. The m6A modification writer WTAP could reduce the mRNA stability of AP-2α in a reader YTHDC1-dependent manner, whereas knockdown of WTAP or YTHDC1 enhances AP-2α expression and decreases lipid accumulation in HCC cells. Clinically, AP-2α expression negatively correlates with the expression of FASN, WTAP, YTHDC1 and the development of liver disease. Taken together, hepatocyte- or macrophage-specific deletion of Tfap2a promotes hepatic steatosis, fibrosis, and the development of HCC. These results suggest that AP-2α has been identified as a novel therapeutic target in fibrosis and inflammation-related HCC, exerting anti-lipogenesis, anti-inflammatory, and anti-tumor multi-roles.

Spatial control of m6A deposition on enhancer and promoter RNAs through co-acetylation of METTL3 and H3K27 on chromatin

Interaction between the N6-methyladenosine (m6A) methyltransferase METTL3 and METTL14 is critical for METTL3 to deposit m6A on various types of RNAs. It remains to be uncovered whether there is spatial control of m6A deposition on different types of RNAs. Here, through genome-wide CRISPR-Cas9 screening in the A549 cell line, we find that H3K27ac acetylase p300-mediated METTL3 acetylation suppresses the binding of METTL3 on H3K27ac-marked chromatin by inhibiting its interaction with METTL14. Consistently, p300 catalyzing the acetylation of METTL3 specifically occurs on H3K27ac-marked chromatin. Disruptive mutations on METTL3 acetylation sites selectively promote the m6A of chromatin-associated RNAs from p300-bound enhancers and promoters marked by H3K27ac, resulting in transcription inhibition of ferroptosis-inhibition-related genes. In addition, PAK2 promotes METTL3 acetylation by phosphorylating METTL3. Inhibition of PAK2 promotes ferroptosis in a manner that depends on the acetylation of METTL3. Our study reveals a spatial-selective way to specifically regulate the deposition of m6A on enhancer and promoter RNAs.

Quantification of Propargylated RNA Nucleosides After Metabolic Labeling Via the Methylation Pathway

RNA modifications are involved in numerous biological processes and vary in different cell types. Methylation is the most widespread type of RNA modification and occurs via S-adenosyl-L-methionine (SAM). We recently developed a metabolic labeling approach based on intracellular formation of a clickable SAM analog (SeAdoYn) and demonstrated its use in mapping methyltransferase (MTase) target sites in mRNA from HeLa cells. Here we investigate how metabolic labeling via the clickable SAM analog modifies four different nucleosides in RNA of HEK293T in comparison to HeLa cells. We find that HEK293T cells retain higher cell viability upon feeding the clickable metabolic SAM precursor. In poly(A)+ RNA we find high Aprop/A levels (0.04 %) and in total RNA (but not poly(A)+ RNA) we detect prop3C, which had not been detected previously in HeLa cells. We discuss the findings in the context of data from the literature with respect to mRNA half-lives in cancer and non-cancer cell lines and suggest that CMTr2 is most likely responsible for the high Aprop level in poly(A)+ RNA.

Decoding N6-methyladenosine's dynamic role in stem cell fate and early embryo development: insights into RNA-chromatin interactions

N6-methyladenosine (m6A), a reversible and dynamic RNA modification, plays pivotal roles in regulating stem cell pluripotency and early embryogenesis. Disruptions in m6A homeostasis lead to profound developmental defects, impairing processes such as stem cell self-renewal, lineage specification, oocyte maturation, zygotic genome activation, and maternal RNA degradation after fertilization. Beyond its well-recognized roles in mRNA transport, stability, and translation, recent studies have highlighted m6A's critical role in transcriptional regulation through intricate RNA-chromatin interactions, notably involving chromatin-associated regulatory RNAs (carRNAs) and retrotransposon RNAs. This review delves into the dynamic regulatory landscape of m6A, highlighting its critical interplay with chromatin modifications, and explores its broader implications in stem cell biology and early embryonic development.

Novel insights into the unique characterization of N6-methyladenosine RNA modification and regulating cold tolerance in winter Brassica rapa

N6-methyladenosine (m6A) is an mRNA modification considered essential in plants, and is a key player in gene regulation at the transcriptional and translational levels. In present study, we mapped Brassica rapa's whole transcriptome m6A profile under low-temperature stress in different cold tolerant varieties to elucidate the m6A methylation pattern. The distribution of m6A modifications changed significantly under low temperature stress. More 5'UTR m6A was deposited in strong cold-resistant varieties and responded positively to cold resistance by regulating mRNA expression abundance. The increase in m6A abundance was correlated with the increase in mRNA abundance after low temperature stress. ZAT12 might positively regulate its mRNA expression through m6A methylation. MYBC1 might be a negative regulator to cope with low-temperature stress. The hypothetical protein was involved in starch and sucrose metabolic pathways, and that the Low-quality protein was involved in the regulation of DNA binding, DNA-binding, transcription factor activity, and proline biosynthetic processes and leaf senescence pathways. In addition, a number of m6A methyltransferases and m6A demethylases play crucial roles in response to cold stress. These results revealed the critical role of m6A -modified genes under cold stress and provide new insights into the study of cold resistance in winter Brassica rapa.

Decoding the regulatory roles of circular RNAs in cardiac fibrosis

Cardiovascular diseases (CVDs) are the primary cause of death globally. The evolution of nearly all types of CVDs is characterized by a common theme: the emergence of cardiac fibrosis. The precise mechanisms that trigger cardiac fibrosis are still not completely understood. In recent years, a type of non-coding regulatory RNA molecule known as circular RNAs (circRNAs) has been reported. These molecules are produced during back splicing and possess significant biological capabilities, such as regulating microRNA activity, serving as protein scaffolds and recruiters, competing with mRNA, forming circR-loop structures to modulate transcription, and translating polypeptides. Furthermore, circRNAs exhibit a substantial abundance, notable stability, and specificity of tissues, cells, and time, endowing them with the potential as biomarkers, therapeutic targets, and therapeutic agents. CircRNAs have garnered growing interest in the field of CVDs. Recent investigations into the involvement of circRNAs in cardiac fibrosis have yielded encouraging findings. This study aims to provide a concise overview of the existing knowledge about the regulatory roles of circRNAs in cardiac fibrosis.

Regulation and application of m6A modification in tumor immunity

The m6A modification is an RNA modification that impacts various processes of RNA molecules, including transcription, splicing, stability, and translation. Recently, researchers have discovered that the presence of m6A modification can influence the interaction between tumor cells and immune cells and also play a role in regulating the expression of immune response-related genes. Additionally, m6A modification is intricately involved in the regulation of tumor immune evasion and drug resistance. Specifically, certain tumor cells can manipulate the gene expression through m6A modification to evade immune system attacks. Therefore, it might be possible to enhance tumor immune surveillance and improve the effectiveness of immune-based therapies by manipulating m6A modification. This review systematically discusses the role of m6A modification in tumor immunity, specifically highlighting its regulation of immune cells and immune-related genes in tumor cells. Furthermore, we explore the potential of m6A modification inhibitors as anti-cancer therapies and the significance of m6A regulatory factors in predicting the efficacy of tumor immune therapy.

Global Co-regulatory Cross Talk Between m6A and m5C RNA Methylation Systems Coordinate Cellular Responses and Brain Disease Pathways

N6 adenosine and C5 cytosine modification of mRNAs, tRNAs and rRNAs are regulated by the behaviour of distinct sets of writer, reader and eraser effector proteins which are conventionally considered to function independently. Here, we provide evidence of global cross-regulatory and functional interaction between the m6A and m5C RNA methylation systems. We first show that m6A and m5C effector protein transcripts are subject to reciprocal base modification supporting the existence of co-regulatory post-transcriptional feedback loops. Using global mass spectrometry proteomic data generated after biological perturbation to identify proteins which change in abundance with effector proteins, we found novel co-regulatory cellular response relationships between m6A and m5C proteins such as between the m6A eraser, ALKBH5, and the m5C writer, NSUN4. Gene ontology analysis of co-regulated proteins indicated that m6A and m5C RNA cross-system control varies across cellular processes, e.g. proteasome and mitochondrial mechanisms, and post-translational modification processes such as SUMOylation and phosphorylation. We also uncovered novel relationships between effector protein networks including contributing to intellectual disability pathways. Finally, we provided in vitro confirmation of colocalisation between m6A-RNAs and the m5C reader protein, ALYREF, after synaptic NMDA activation. These findings have important implications for understanding control of RNA metabolism, cellular proteomic responses, and brain disease mechanisms.

The RNA m6A Methyltransferase PheMTA1 and PheMTA2 of Moso Bamboo Regulate Root Development and Resistance to Salt Stress in Plant

As the most prevalent RNA modification in eukaryotes, N6-methyladenosine (m6A) plays a crucial role in regulating various biological processes in plants, including embryonic development and flowering. However, the function of m6A RNA methyltransferase in moso bamboo remains poorly understood. In this study, we identified two m6A methyltransferases in moso bamboo, PheMTA1 and PheMTA2. Overexpression of PheMTA1 and PheMTA2 significantly promoted root development and enhanced salt tolerance in rice. Using the HyperTRIBE method, we fused PheMTA1 and PheMTA2 with ADARcdE488Q and introduced them into rice. RNA sequencing (RNA-seq) of the overexpressing rice identified the target RNAs bound by PheMTA1 and PheMTA2. PheMTA1 and PheMTA2 bind to OsATM3 and OsSF3B1, which were involved in the development of root and salt resistance. Finally, we revealed the effects of transcription or alternative splicing on resistance-related genes like OsRS33, OsPRR73, OsAPX2 and OsHAP2E, which are associated with the observed phenotype. In conclusion, our study demonstrates that the m6A methyltransferases PheMTA1 and PheMTA2 from moso bamboo are involved in root development and enhance plant resistance to salt stress.

XIAP promotes metastasis of bladder cancer cells by ubiquitylating YTHDC1

X-linked inhibitor of apoptosis protein (XIAP), a member of the IAP family, is overexpressed in a variety of tumors and plays an important role in tumor progression. Increasing evidence suggests that XIAP promotes metastasis of bladder cancer but the underlying mechanism is not very clear. The RNA N6-methyladenosine (m6A) reader YTHDC1 regulates RNA splicing, nuclear transport, and mRNA stability and is a potential tumor target; however, its ubiquitin E3 ligase has not been described. In this study, screening of proteins that specifically interact with XIAP identified YTHDC1 as its degradation substrate. Ectopic overexpression of XIAP promoted degradation of YTHDC1, and knockout of XIAP upregulated YTHDC1, which inhibited metastasis of bladder cancer. Furthermore, YTHDC1 reduced the expression of matrix metalloproteinase-2 (MMP-2) by destabilizing its mRNA. These experiments revealed that XIAP promotes ubiquitination of YTHDC1, positively regulating expression of the MMP-2 and promoting metastasis of bladder cancer. Collectively, these findings demonstrate that XIAP is a critical regulator of YTHDC1 and pinpoint the XIAP/YTHDC1/MMP-2 axis as a promising target for the treatment of bladder cancer.

YTHDC1 cooperates with the THO complex to prevent RNA-damage-induced DNA breaks

Certain environmental toxins and chemotherapeutics are nucleic acid-damaging agents, causing adducts in DNA and RNA. While most of these adducts occur in RNA, the consequences of RNA damage are largely unexplored. Here, we demonstrate that nuclear RNA damage can result in loss of genome integrity in human cells. Specifically, we show that YTHDC1 regulates alkylation damage responses with the THO complex (THOC). In addition to its established binding to N6-methyladenosine (m6A), YTHDC1 binds to chemically induced N1-methyladenosine (m1A). Without YTHDC1, cells have greater alkylation damage sensitivity and increased DNA breaks, which are rescued by an RNA-specific dealkylase. These RNA-damage-induced DNA breaks (RDIBs) depend on R-loop formation, which is converted to DNA breaks by the XPG nuclease. Strikingly, in the absence of YTHDC1 or THOC, a nuclear RNA m1A methyltransferase is sufficient to induce DNA breaks. Our results provide mechanistic insight into how damaged RNAs can impact genomic integrity.

Review of the role and potential clinical value of m6A methylation modifications in the biological process of osteosarcoma

Osteosarcoma (OS), an aggressive bone tumor, is a substantial threat to the quality of life and survival of affected individuals. Despite recent improvements in OS therapies, the considerable variability and chemotherapy resistance of this cancer necessitate continuous research to discover new treatment targets and biomarkers. Recent epigenetic advances highlight the crucial role of N6-methyladenosine (m6A) methylation in cancer. In OS, m6A methylation has been demonstrated to be a pivotal component in the pathogenesis. This review introduces new findings regarding the association between m6A methylation regulators and OS, and summarizes the potential clinical applications of OS and m6A methylation regulators, including the role of m6A methylation in OS proliferation, growth, apoptosis, and cell migration, invasion, and metastasis; relationship between m6A methylation and OS chemotherapy resistance; and relationship between m6A methylation and OS prognosis. Our review had certain limitations. The interaction between m6A methylation regulators and other oncogenic factors, such as lncRNAs and ncRNAs, is not fully understood. We hope that these potential methods will be translated into clinical applications and effective treatment.

YTHDF1 and YTHDC1 m6A reader proteins regulate HTLV-1 tax and hbz activity

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus responsible for adult T-cell leukemia/lymphoma (ATLL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a progressive neurodegenerative disease. Regulation of viral gene expression plays a key role in viral persistence and pathogenesis. However, the molecular mechanisms underlying this fine-tuned regulation remain poorly understood. Little is known regarding RNA chemical modifications of HTLV-1 RNA and how these affect viral biology and disease development. Post-transcriptional chemical modification of RNA is common in eukaryotes, with N6-methyladenosine (m6A) being the most prevalent. In this study, we investigated the role of m6A RNA modifications on HTLV-1 gene expression. Using MeRIP-Seq, we mapped the sites of m6A modification to the 3' end of the viral genome. We found HTLV-1 RNA, as well as viral oncogene transcripts tax and hbz, contained m6A modifications. m6A-depletion in HTLV-1-transformed cells decreased sense-derived viral genes (Tax, Gag, and Env) and increased antisense-derived Hbz expression. Tax and hbz transcripts were bound by reader proteins YTHDF1 and YTHDC1 in a panel of HTLV-1 T-cell lines. Using expression vectors and shRNA-mediated knockdown, we found that YTHDF1 had opposing effects on viral gene expression, decreasing sense-derived viral genes and increasing antisense-derived Hbz. Upon further study, the YTHDF1 effects on tax abundance were dependent on tax m6A deposition. The nuclear m6A reader protein YTHDC1 affected the abundance of both sense- and antisense-derived viral transcripts and specifically enhanced the nuclear export of tax transcript. Collectively, our results demonstrate global m6A levels and m6A reader proteins YTHDF1 and YTHDC1 regulate HTLV-1 gene expression.IMPORTANCEHuman T-cell leukemia virus type 1 (HTLV-1) persistence and pathogenesis are controlled through tight regulation of viral gene expression. The fate of RNA can be controlled by epigenetic modifications that impact gene expression without altering the DNA sequence. Our study details the impact of N6-methyladenosine (m6A) RNA chemical modifications on HTLV-1 gene expression. We found that reductions in global m6A levels affected viral gene expression, decreasing Tax and other sense-derived viral genes, whereas increasing the antisense-derived Hbz. Our results suggest the oncogenic viral transcripts, tax and hbz, are m6A-modified in cells. We found that these viral RNA modifications are interpreted by reader proteins YTHDF1 and YTHDC1, which dictate the fate of the viral RNA. Understanding HTLV-1 RNA chemical modifications offers potential insights into novel therapeutic strategies for HTLV-1-associated diseases.

m6A RNA methylation dynamics during in vitro maturation of cumulus-oocyte complexes derived from adult or prepubertal sheep

PURPOSE

N6-methyladenosine (m6A) is the most prevalent base epigenetic modification within eukaryotic mRNAs. It participates in post-transcriptional regulation, including maternal RNA maintenance and decay in mouse oocytes and during maternal-to-zygotic transition. The landscape in other mammalian species remains largely unexplored. The present work analyzed m6A dynamics in sheep cumulus oocyte complexes (COCs), during in vitro maturation. To explore potential relationships with oocyte developmental competence, a previously established model consisting of oocytes derived from adult and prepubertal sheep was adopted.

METHODS

m6a dynamics were analyzed in terms of m6A RNA methylation abundance in cumulus cells (CCs) by colorimetric assay and expression of key m6A methylation-related proteins (METTL3, METTL14, METTL16, VIRMA, YTHDC1, YTHDC2, YTHDF2, YTHDF3, ALKBH5, and FTO) in both cumulus cells and oocytes by real-time PCR.

RESULTS

We report the dynamics of m6A in sheep COCs, and reveal alterations in both oocytes and cumulus cells derived from prepubertal donors. These changes were observed in terms of m6A RNA methylation levels and transcript dynamics of several m6A methylation-related proteins. Notably, our study shows that dysregulations occur after IVM.

CONCLUSION

Overall, this work describes for the first time the dynamics of m6A in sheep COCs and uncovers the involvement of m6A RNA methylation in oocyte developmental potential.

OSGEP, A Negative Ferroptotic Regulator, Alleviates Cerebral Ischemia-Reperfusion Injury Through Modulating m6A Methylation of GPX4 mRNA

Cerebral ischemia-reperfusion injury (CIRI) is a devastating condition that triggers neuronal death and cerebral infarction. O-sialoglycoprotein endopeptidase (OSGEP), identified as a crucial element of the highly conserved KEOPS complex, regulated cellular proliferation and mitochondrial metabolism. Despite its known role in cellular homeostasis, the potential contribution of OSGEP to the development of CIRI remains elusive. This study was designed to investigate the potential role of ferroptosis in the pathogenesis of CIRI and indicate whether OSGEP could suppress ferroptosis to alleviate CIRI by modulating GPX4 m6A methylation. To this end, MCAO and OGD/R models were employed to closely simulate the CIRI. The potent ferroptosis inhibitors conferred prominent neuroprotection in both in vivo and in vitro models. Moreover, OSGEP expression level was not only downregulated in MCAO-treated mice and in cultured cerebrocortical neurons subjected to OGD/R, but also it was related to the prognosis of acute ischemic stroke (AIS) cases. Additionally, OSGEP overexpression exerted potent anti-ferroptotic effects in both MCAO and OGD/R models, while OSGEP depletion exhibited the opposite effect. Moreover, OSGEP regulated GPX4 expression by modulating m6A methylation of its mRNA. Furthermore, the inhibitory effect of OSGEP on ferroptosis was dependent on the presence of GPX4. Specifically, OSGEP knockout exacerbated ferroptosis-like cell death under MCAO condition. Besides, OSGEP regulated GPX4 mRNA stability through competition with YTHDC1 for binding to GPX4 mRNA and forming a complex with HNRNPUL1 in the neuronal primary cultures subjected to OGD/R. These findings highlighted the critical role of OSGEP, as a new contributing anti-ferroptotic factor, in the pathogenesis of CIRI.

YTHDC1 negatively regulates UBE3A to influence RAD51 ubiquitination and inhibit apoptosis in colorectal cancer cells

YTHDC1, a key protein in the m6A-related regulatory network within cells, is involved in multiple cellular processes such as chromatin-related regulation, RNA splicing, and nuclear export. Understanding its role in colorectal cancer (CRC) development and DNA damage repair is critical for the advancement of treatment strategies. Our study found that YTHDC1 was highly expressed in high-malignancy CRC tissues compared with low-malignancy ones. Upon silencing YTHDC1, we observed a pronounced suppression of the proliferation of CRC cell lines, accompanied by a substantial increase in cell apoptosis. Furthermore, we identified RAD51 as a crucial downstream target of YTHDC1. Knocking down YTHDC1 led to a notable decrease in RAD51 protein levels, and silencing RAD51 also inhibited cancer cell proliferation. Interestingly, RNA-sequencing data indicated that the YTHDC1 deletion did not affect RAD51 transcription. However, Western blot revealed that this deletion increased the ubiquitination of RAD51, likely due to the upregulated E3 ligase UBE3A. Ubiquitination experiments subsequently confirmed that RAD51 is indeed one of the substrates of UBE3A. In summary, our study provides novel insights into how YTHDC1 modulates the expression of RAD51 through post-translational modifications. These findings offer valuable information that may potentially contribute to the development of more effective therapeutic strategies for CRC.

SRSF3 and hnRNP A1-mediated m6A-modified circCDK14 regulates intramuscular fat deposition by acting as miR-4492-z sponge

The intramuscular fat (IMF) content of yak beef is critical for determining its quality. Circular RNAs (circRNAs) are a group of endogenous non-coding RNAs that have emerged as important factors in the regulation of IMF deposition. However, the molecular mechanisms through which circRNAs regulate IMF deposition, particularly in yaks, remain unclear. In the present study, a novel circRNA, circCDK14 (originating from the yak's CDK14 gene), was identified by sequencing and RNase R treatment. In our previous study, we successfully established a ceRNA network map and identified miR-4492-z, which interacts with circCDK14. Furthermore, using methylation prediction software, we predicted two genes, SRSF3 and hnRNP A1, that have a strong binding relationship with circCDK14; existing research has confirmed their close association with m6A methylation modifications. On the basis of these findings, we comprehensively evaluated the effects of circCDK14, miR-4492-z, SRSF3 and hnRNP A1 on the proliferation and differentiation of yak intramuscular pre-adipocytes using EdU, CCK-8, BODIPY, Oil Red O and qRT-PCR analyses. Mechanistically, the interaction between circCDK14 and miR-4492-z was validated using a dual-luciferase reporter gene assay and rescue experiments. RIP assays revealed the binding interaction of circCDK14 with SRSF3 and hnRNP A1. The MeRIP experiments showed modification of circCDK14 methylation, with SRSF3 and hnRNP A1 promoting the methylation and translocation of circCDK14 from the nucleus to the cytoplasm. In summary, our results suggest that m6A-modified circCDK14 plays a crucial role as an miR-4492-z sponge in regulating IMF deposition in yaks and that the nuclear export of circCDK14 correlates with the expression levels of SRSF3 and hnRNP A1. This study provides a theoretical basis for the improvement of yak meat quality and promotes the development of molecular yak breeding.

Post-Transcriptional Regulation of Gene Expression and the Intricate Life of Eukaryotic mRNAs

In recent years, there has been a growing appreciation for how regulatory events that occur either co- or post-transcriptionally contribute to the control of gene expression. Messenger RNAs (mRNAs) are extensively regulated throughout their metabolism in a precise spatiotemporal manner that requires sophisticated molecular mechanisms for cell-type-specific gene expression, which dictates cell function. Moreover, dysfunction at any of these steps can result in a variety of human diseases, including cancers, muscular atrophies, and neurological diseases. This review summarizes the steps of the central dogma of molecular biology, focusing on the post-transcriptional regulation of gene expression.

DNA damage-induced YTHDC1 O-GlcNAcylation promotes homologous recombination by enhancing m6A binding

N6-methyladenosine (m6A) is the most prevalent internal RNA modification, and its regulators include writers, readers and erasers. m6A is under stringent control and takes part in many biological events, but it is not known whether there is an interplay between m6A and glycosylation. Here we investigated an m6A reader, YTHDC1, which has been shown to be recruited to the DNA-RNA hybrid at DNA damage sites and regulate homologous recombination (HR) during DNA damage repair. We found that YTHDC1 is subject to O-linked β-N-acetylglucosamine (O-GlcNAc) modification at Ser396 upon DNA damage, which is pivotal for YTHDC1 chromatin binding and ionization radiation induced focus (IRIF) formation. RNA immunoprecipitation (RIP) and molecular dynamics (MD) simulations indicate that O-GlcNAcylation is vital for YTHDC1 to bind with m6A RNA. Fluorescence recovery after photo bleaching (FRAP) analysis revealed that YTHDC1 O-GlcNAcylation is essential for DNA damage-induced YTHDC1-m6A condensate formation. We further demonstrate that YTHDC1 O-GlcNAcylation promotes HR-mediated DNA damage repair and cell survival, probably through recruitment of Rad51 to the damage sites. We propose that YTHDC1 O-GlcNAcylation is instrumental for HR.

METTL3-mediated m6A modification regulates muscle development by promoting TM4SF1 mRNA degradation in P-body via YTHDF2

N6-methyladenosine (m6A), a well-known post-transcriptional modification, is implicated in diverse cellular and physiological processes. However, much remains unknown regarding the precise role and mechanism of m6A modification on muscle development. In this study, we make observation that the levels of m6A and METTL3 are markedly elevated during the differentiation phase (DM) compared to the growth phase (GM) in both C2C12 and bovine myoblasts. Notably, deletion of METTL3 decreased m6A levels, and promoted myoblast proliferation, inhibited myoblast differentiation in vitro. By performing m6A sequencing in both GM and DM myoblast, we further identified that TM4SF1 is involved in m6A -regulated muscle development. Mechanistically, METTL3 increases m6A-modified TM4SF1 transcripts, and subsequently YTHDF2 promotes TM4SF1 mRNA degradation in P-body through liquid-liquid phase separation (LLPS). Additionally, the rescue experiments in vivo showed that overexpressing METTL3 could rescue the attenuated myogenesis induced by TM4SF1 overexpression during muscle regeneration in mice. Collectively, our findings shed light on a regulatory mechanism by which m6A modulates muscle development and raise a new model for m6A-mediated mRNA degradation within P-bodies.

The transcriptional regulation of Arabidopsis ECT8 by ABA-Responsive Element binding transcription factors in response to ABA and abiotic stresses

N 6-methyladenosine modification is a critical epigenetic mark in the plant response to abscisic acid (ABA) and various abiotic stresses including salinity, drought, and cold stresses. Arabidopsis Evolutionarily Conserved C-Terminal Region 8 (ECT8), an m6A reader, has been reported to participate in the response to ABA and salinity stress. However, the intricate regulatory mechanisms governing ECT8 expression in these stress responses have not been fully elucidated. Our multidisciplinary analyses have revealed that ECT8 exhibits a broad expression pattern across tissues, with particularly high levels observed in senescent leaves. Furthermore, ECT8 expression is markedly upregulated in response to ABA, salinity, and osmotic stress. Intriguingly, the promoter region of the ECT8 gene harbors two ABA Responsive Elements (ABREs). Employing yeast one-hybrid assays, we identified that key ABRE-binding transcription factors within the ABA signaling cascade, namely ABA INSENSITIVE 5 (ABI5) and ABRE BINDING FACTOR1/2/3/4 (ABF1/2/3/4), exhibit a specific binding affinity for the ECT8 promoter, with the two ABREs indispensable for their interaction. The Dual-Luciferase Reporter assay and Chromatin immunoprecipitation assay confirmed their interaction in planta. The expression pattern of ECT8 in mutants deficient in the core components of the ABA signaling pathway indicated that ECT8 is modulated by ABI5/ABF-mediated ABA signaling. Collectively, our findings elucidate the feedback mechanism linking ABA perception to the regulation of ECT8 expression, thereby shedding new light on the intricate interplay between ABA signaling and RNA m6A modification. This discovery enriches our understanding of the molecular crosstalk that underpins plant stress responses.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-025-01565-7.

Exon junction complexes regulate osteoclast-induced bone resorption by influencing the NFATc1 m6A distribution through the "shield effect"

BACKGROUND

The distribution of the m6A methylation modification on the transcriptome is highly regionally selective and is mainly concentrated in abnormally long exons and stop codons. However, in-depth research on the selective mechanism of m6A methylation is still lacking.

METHODS

In this research, meRIP sequencing, mRNA sequencing, meRIP, luciferase reporter assays and CRISPR/Cas9 conditional knockout mice were used to elucidate the distribution characteristics of NFATc1 m6A.

RESULTS

METTL14 controls osteoclast-mediated bone resorption by means of the methylation (4249 A) of the NFATc1 gene during osteoclast differentiation. Exon junction complexes (EJCs) selectively protect the m6A methylation sites of the NFATc1 gene. When the methylation sites are located within short exon fragments (50-200 nt), EJCs prevent their hypermethylation and degradation through the "shield effect"; when the methylation sites are located in the 3' UTR region or long exon fragments (greater than 300 nt), the "shield effect" disappears. Downstream, YTHDF2 induced the degradation of hypermethylation NFATc1 transcripts without site restriction.

CONCLUSIONS

EJCs act as "shields" to regulate the m6A region selectivity of the NFATc1 gene, thereby determining the characteristics of m6A distribution in the gene. Importantly, EJCs can raise the level of m6A methylation of NFATc1 and degrade its mRNA, thereby inhibiting osteoclast differentiation and preserving bone mass. These results will be helpful for identifying potential molecular targets for osteoporosis treatment.

KEY POINTS

METTL14 controls osteoclast-mediated bone resorption by means of the methylation (4249 A) of the NFATc1 gene during osteoclast differentiation. Exon junction complexes (EJCs) protect the remaining methylation sites of the NFATc1 gene (located in the inner exon fragment of 50-200 nt) from hypermethylation and degradation. The "shield effect" disappears when the exon fragment is extended to 300 nt. Downstream, YTHDF2 induced the degradation of hypermethylation NFATc1 transcripts without site restriction.

m6A RNA methylation: a pivotal regulator of tumor immunity and a promising target for cancer immunotherapy

M6A modification is one of the most common regulatory mechanisms of gene expression in eukaryotic cells, influencing processes such as RNA splicing, degradation, stability, and protein translation. Studies have shown that m6A methylation is closely associated with tumorigenesis and progression, and it plays a key regulatory role in tumor immune responses. m6A modification participates in regulating the differentiation and maturation of immune cells, as well as related anti-tumor immune responses. In the tumor microenvironment, m6A modification can also affect immune cell recruitment, activation, and polarization, thereby promoting or inhibiting tumor cell proliferation and metastasis, and reshaping the tumor immune microenvironment. In recent years, immunotherapies for tumors, such as immune checkpoint inhibitors and adoptive cell immunotherapy, have been increasingly applied in clinical settings, achieving favorable outcomes. Targeting m6A modifications to modulate the immune system, such as using small-molecule inhibitors to target dysregulated m6A regulatory factors or inducing immune cell reprogramming, can enhance anti-tumor immune responses and strengthen immune cell recognition and cytotoxicity against tumor cells. m6A modification represents a new direction in tumor immunotherapy with promising clinical potential. This review discusses the regulatory role of m6A methylation on immune cells and tumor immune responses and explores new strategies for immunotherapy.

The m6A revolution: transforming tumor immunity and enhancing immunotherapy outcomes

N6-methyladenosine (m6A), the most prevalent RNA modification in eukaryotes, plays a critical role in the development and progression of various diseases, including cancer, through its regulation of RNA degradation, stabilization, splicing, and cap-independent translation. Emerging evidence underscores the significant role of m6A modifications in both pro-tumorigenic and anti-tumorigenic immune responses. In this review, we provide a comprehensive overview of m6A modifications and examine the relationship between m6A regulators and cancer immune responses. Additionally, we summarize recent advances in understanding how m6A modifications influence tumor immune responses by directly modulating immune cells (e.g., dendritic cells, tumor-associated macrophages, and T cells) and indirectly affecting cancer cells via mechanisms such as cytokine and chemokine regulation, modulation of cell surface molecules, and metabolic reprogramming. Furthermore, we explore the potential synergistic effects of targeting m6A regulators in combination with immune checkpoint inhibitor (ICI) therapies. Together, this review consolidates current knowledge on the role of m6A-mediated regulation in tumor immunity, offering insights into how a deeper understanding of these modifications may identify patients who are most likely to benefit from immunotherapies.

RNA N6-methyladenosine modification in arthritis: New insights into pathogenesis

The commonest type of eukaryotic RNA modification, N6-methyladenosine (m6A), has drawn increased scrutiny in the context of pathological functioning as well as relevance in determination of RNA stability, splicing, transportation, localization, and translation efficiency. The m6A modification plays an important role in several types of arthritis, especially osteoarthritis and rheumatoid arthritis. Recent studies have reported that m6A modification regulates arthritis pathology in cells, such as chondrocytes and synoviocytes via immune responses and inflammatory responses through functional proteins classified as writers, erasers, and readers. The aim of this review was to highlight recent advances relevant to m6A modification in the context of arthritis pathogenesis and detail underlying molecular mechanisms, regulatory functions, clinical applications, and future perspectives of m6A in arthritis with the aim of providing a foundation for future research directions.

N 6-methyladenosine reader YTHDF2 in cell state transition and antitumor immunity

Recent studies have revealed that the YTHDF family proteins bind preferentially to the N 6-methyladenosine (m6A)-modified mRNA and regulate the functions of these RNAs in different cell types. YTHDF2, the first identified m6A reader in mammals, has garnered significant attention because of its profound effect to regulate the m6A epitranscriptome in multiple biological processes. Here, we review current knowledge on the mechanisms by which YTHDF2 exerts its functions and discuss recent advances that underscore the multifaceted role of YTHDF2 in development, stem cell expansion, and immune evasion. We also highlight potential therapeutic interventions targeting the m6A/YTHDF2 axis to improve the response to current antitumor therapies.

Advanced reactivity-based sequencing methods for mRNA epitranscriptome profiling

Currently, over 170 chemical modifications identified in RNA introduce an additional regulatory attribute to gene expression, known as the epitranscriptome. The development of detection methods to pinpoint the location and quantify these dynamic and reversible modifications has significantly expanded our understanding of their roles. This review goes deep into the latest progress in enzyme- and chemical-assisted sequencing methods, highlighting the opportunities presented by these reactivity-based techniques for detailed characterization of RNA modifications. Our survey provides a deeper understanding of the function and biological roles of RNA modification.

N6-methyladenosine in inflammatory diseases: Important actors and regulatory targets

N6-methyladenosine (m6A) is one of the most prevalent epigenetic modifications in eukaryotic cells. It regulates RNA function and stability by modifying RNA methylation through writers, erasers, and readers. As a result, m6A plays a critical role in a wide range of biological processes. Inflammation is a common and fundamental pathological process. Numerous studies have investigated the role of m6A modifications in inflammatory diseases. This review highlights the mechanisms by which m6A contributes to inflammation, focusing on pathogen-induced infectious diseases, autoimmune disorders, allergic conditions, and metabolic disorder-related inflammatory diseases.

Epigenetic regulation in female reproduction: the impact of m6A on maternal-fetal health

With the development of public health, female diseases have become the focus of current concern. The unique reproductive anatomy of women leads to the development of gynecological diseases gradually become an important part of the socio-economic burden. Epigenetics plays an irreplaceable role in gynecologic diseases. As an important mRNA modification, m6A is involved in the maturation of ovum cells and maternal-fetal microenvironment. At present, researchers have found that m6A is involved in the regulation of gestational diabetes and other reproductive system diseases, but the specific mechanism is not clear. In this manuscript, we summarize the components of m6A, the biological function of m6A, the progression of m6A in the maternal-fetal microenvironment and a variety of gynecological diseases as well as the progression of targeted m6A treatment-related diseases, providing a new perspective for clinical treatment-related diseases.