YTHDC1 mediates nuclear export of N6-methyladenosine methylated mRNAs

Role of N6-methyladenosine methylation in nasopharyngeal carcinoma: current insights and future prospective

Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck squamous cell carcinoma prevalent in Southern China, Southeast Asia, and North Africa. Despite advances in treatment options, the prognosis for advanced NPC remains poor, underscoring the urgent need to explore its underlying mechanisms and develop novel therapeutic strategies. Epigenetic alterations have been shown to play a key role in NPC progression. Recent studies indicate that dysregulation of RNA modifications in NPC specifically affects tumor-related transcripts, influencing various oncogenic processes. This review provides a comprehensive overview of altered RNA modifications and their regulators in NPC, with a focus on m6A and its regulatory mechanisms. We discuss how m6A RNA modification influences gene expression and affects NPC initiation and progression at the molecular level, analyzing its impact on cancer-related biological functions. Understanding these modifications could reveal new biomarkers and therapeutic targets for NPC, offering promising directions for future research and precision medicine.

When animal viruses meet N6-methyladenosine (m6A) modifications: for better or worse?

N6-methyladenosine (m6A) is a prevalent and dynamic RNA modification, critical in regulating gene expression. Recent research has shed light on its significance in the life cycle of viruses, especially animal viruses. Depending on the context, these modifications can either enhance or inhibit the replication of viruses. However, research on m6A modifications in animal virus genomes and the impact of viral infection on the host cell m6A landscape has been hindered due to the difficulty of detecting m6A sites at a single-nucleotide level. This article summarises the methods for detecting m6A in RNA. It then discusses the progress of research into m6A modification within animal viruses' infections, such as influenza A virus, porcine epidemic diarrhoea virus, porcine reproductive, and respiratory syndrome virus. Finally, the review explores how m6A modification affects the following three aspects of the replication of animal RNA viruses: the regulation of viral genomic RNA function, the alteration of the m6A landscape in cells after viral infection, and the modulation of antiviral immunity through m6A modification. Research on m6A modifications in viral RNA sheds light on virus-host interactions at a molecular level. Understanding the impact of m6A on viral replication can help identify new targets for antiviral drug development and may uncover novel regulatory pathways that could potentially enhance antiviral immune responses.

A Demethylation-Switchable Aptamer Design Enables Lag-Free Monitoring of m6A Demethylase FTO with Energy Self-Sufficient and Structurally Integrated Features

Cellular context profiling of modification effector proteins is critical for an in-depth understanding of their biological roles in RNA N6-methyladenosine (m6A) modification regulation and function. However, challenges still remain due to the high context complexities, which call for a versatile toolbox for accurate live-cell monitoring of effectors. Here, we propose a demethylation-switchable aptamer sensor engineered with a site-specific m6A (DSA-m6A) for lag-free monitoring of the m6A demethylase FTO activity in living cells. As a proof of concept, a DNA aptamer against adenosine triphosphate (ATP) is selected to construct the DSA-m6A model, as the "universal energy currency" role of ATP could guarantee the equally fast and spontaneous conformation change of DSA-m6A sensor upon demethylation and ATP binding in living organisms, thus enabling sensitive monitoring of FTO activity with neither time delay nor recourse to extra supply of substances. This ATP-driven DSA-m6A design facilitates biomedical research, including live-cell imaging, inhibitor screening, single-cell tracking of dynamic FTO nuclear translocation upon starvation stimuli, FTO characterization in a biomimetic heterotypic three-dimensional (3D) multicellular spheroid model, as well as the first report on the in vivo imaging of FTO activity. This strategy provides a simple yet versatile toolbox for clinical diagnosis, drug discovery, therapeutic evaluation, and biological study of RNA demethylation.

The role of RNA modifications in disease-associated macrophages

In recent years, the field of epitranscriptomics has witnessed significant breakthroughs with the identification of more than 150 different chemical modifications in different RNA species. It has become increasingly clear that these chemical modifications play an important role in the regulation of fundamental processes linked to cell fate and development. Further interest was sparked by the ability of the epitranscriptome to regulate pathogenesis. However, despite the involvement of macrophages in a multitude of diseases, a clear knowledge gap exists in the understanding of how RNA modifications regulate the phenotype of these cells. Here, we provide a comprehensive overview of the known roles of macrophage RNA modifications in the context of different diseases.

m6A sites in the coding region trigger translation-dependent mRNA decay

N6-Methyladenosine (m6A) is the predominant internal RNA modification in eukaryotic messenger RNAs (mRNAs) and plays a crucial role in mRNA stability. Here, using human cells, we reveal that m6A sites in the coding sequence (CDS) trigger CDS-m6A decay (CMD), a pathway that is distinct from previously reported m6A-dependent degradation mechanisms. Importantly, CDS m6A sites act considerably faster and more efficiently than those in the 3' untranslated region, which to date have been considered the main effectors. Mechanistically, CMD depends on translation, whereby m6A deposition in the CDS triggers ribosome pausing and transcript destabilization. The subsequent decay involves the translocation of the CMD target transcripts to processing bodies (P-bodies) and recruitment of the m6A reader protein YT521-B homology domain family protein 2 (YTHDF2). Our findings highlight CMD as a previously unknown pathway, which is particularly important for controlling the expression of developmental regulators and retrogenes.

The role of N6-methyladenosine modification in tumor angiogenesis

Tumor angiogenesis is a characteristics of malignant cancer progression that facilitates cancer cell growth, diffusion and metastasis, and has an indispensable role in cancer development. N6-methyladenosine (m6A) is among the most prevalent internal modifications in eukaryotic RNAs, and has considerable influence on RNA metabolism, including its transcription, splicing, localization, translation, recognition, and degradation. The m6A modification is generated by m6A methyltransferases ("writers"), removed by m6A demethylases ("erasers"), and recognized by m6A-binding proteins ("readers"). There is accumulating evidence that abnormal m6A modification is involved in the pathogenesis of multiple diseases, including cancers, and promotes cancer occurrence, development, and progression through its considerable impact on oncoprotein expression. Furthermore, increasing studies have demonstrated that m6A modification can influence angiogenesis in cancers through multiple pathways to regulate malignant processes. In this review, we elaborate the role of m6A modification in tumor angiogenesis-related molecules and pathways in detail, providing insights into the interactions between m6A and tumor angiogenesis. Moreover, we describe how targeting m6A modification in combination with anti-angiogenesis drugs is expected to be a promising anti-tumor treatment strategy, with potential value for addressing the challenge of drug resistance.

The METHYLTRANSFERASE B-SERRATE interaction mediates the reciprocal regulation of microRNA biogenesis and RNA m6A modification

In eukaryotes, RNA N6-methyladenosine (m6A) modification and microRNA (miRNA)-mediated RNA silencing represent two critical epigenetic regulatory mechanisms. The m6A methyltransferase complex (MTC) and the microprocessor complex both undergo liquid-liquid phase separation to form nuclear membraneless organelles. Although m6A methyltransferase has been shown to positively regulate miRNA biogenesis, a mechanism of reciprocal regulation between the MTC and the microprocessor complex has remained elusive. Here, we demonstrate that the MTC and the microprocessor complex associate with each other through the METHYLTRANSFERASE B (MTB)-SERRATE (SE) interacting module. Knockdown of MTB impaired miRNA biogenesis by diminishing microprocessor complex binding to primary miRNAs (pri-miRNAs) and their respective MIRNA loci. Additionally, loss of SE function led to disruptions in transcriptome-wide m6A modification. Further biochemical assays and fluorescence recovery after photobleaching (FRAP) assay indicated that SE enhances the liquid-liquid phase separation and solubility of the MTC. Moreover, the MTC exhibited enhanced retention on chromatin and diminished binding to its RNA substrates in the se mutant background. Collectively, our results reveal the substantial regulatory interplay between RNA m6A modification and miRNA biogenesis.

Reading m6A marks in mRNA: A potent mechanism of gene regulation in plants

Modifications to RNA have recently been recognized as a pivotal regulator of gene expression in living organisms. More than 170 chemical modifications have been identified in RNAs, with N6-methyladenosine (m6A) being the most abundant modification in eukaryotic mRNAs. The addition and removal of m6A marks are catalyzed by methyltransferases (referred to as "writers") and demethylases (referred to as "erasers"), respectively. In addition, the m6A marks in mRNAs are recognized and interpreted by m6A-binding proteins (referred to as "readers"), which regulate the fate of mRNAs, including stability, splicing, transport, and translation. Therefore, exploring the mechanism underlying the m6A reader-mediated modulation of RNA metabolism is essential for a much deeper understanding of the epigenetic role of RNA modification in plants. Recent discoveries have improved our understanding of the functions of m6A readers in plant growth and development, stress response, and disease resistance. This review highlights the latest developments in m6A reader research, emphasizing the diverse RNA-binding domains crucial for m6A reader function and the biological and cellular roles of m6A readers in the plant response to developmental and environmental signals. Moreover, we propose and discuss the potential future research directions and challenges in identifying novel m6A readers and elucidating the cellular and mechanistic role of m6A readers in plants.

Optimizing ABA-based chemically induced proximity for enhanced intracellular transcriptional activation and modification response to ABA

Abscisic acid (ABA)-based chemically induced proximity (CIP) is primarily mediated by the interaction of the ABA receptor pyrabactin resistance 1-like 1 (PYL1) and the 2C-type protein phosphatase ABI1, which confers ABA-induced proximity to their fusion proteins, and offers precise temporal control of a wide array of biological processes. However, broad application of ABA-based CIP has been limited by ABA response intensity. In this study, we demonstrated that ABA-induced interaction between another ABA receptor pyrabactin resistance 1 (PYR1) and ABI1 exhibited higher ABA response intensity than that between PYL1 and ABI1 in HEK293T cells. We engineered PYR1-ABI1 and PYL1-ABI1 into ABA-induced transcriptional activation tools in mammalian cells by integration with CRISPR/dCas9 and found that the tool based on PYR1-ABI1 demonstrated better ABA response intensity than that based on PYL1-ABI1 for both exogenous and endogenous genes in mammalian cells. We further achieved ABA-induced RNA m6A modification installation and erasure by combining ABA-induced PYR1-ABI1 interaction with CRISPR/dCas13, successfully inhibiting tumor cell proliferation. We subsequently improved the interaction of PYR1-ABI1 through phage-assisted continuous evolution (PACE), successfully generating a PYR1 mutant (PYR1m) whose interaction with ABI1 exhibited a higher ABA response intensity than that of the wild-type. In addition, we tested the transcriptional activation tool based on PYRm-ABI1 and found that it also showed a higher ABA response intensity than that of the wild type. These results demonstrate that we have developed a novel ABA-based CIP and further improved upon it using PACE, providing a new approach for the modification of other CIP systems.

N6-Methyladenosine Modification on the Function of Female Reproductive Development and Related Diseases

BACKGROUND

N6-methyladenosine (m6A) modification is a widespread and reversible epigenetic alteration in eukaryotic mRNA, playing a pivotal role in various biological functions. Its significance in female reproductive development and associated diseases has recently become a focal point of research.

OBJECTIVE

This review aims to consolidate current knowledge of the role of m6A modification in female reproductive tissues, emphasizing its regulatory dynamics, functional significance, and implications in reproductive health and disease.

METHODS

A comprehensive analysis of recent studies focusing on m6A modification in ovarian development, oocyte maturation, embryo development, and the pathogenesis of reproductive diseases.

RESULTS

m6A modification exhibits dynamic regulation in female reproductive tissues, influencing key developmental stages and processes. It plays critical roles in ovarian development, oocyte maturation, and embryo development, underpinning essential aspects of reproductive health. m6A modification is intricately involved in the pathogenesis of several reproductive diseases, including polycystic ovary syndrome (PCOS), premature ovarian failure (POF), and endometriosis, offering insights into potential molecular mechanisms and therapeutic targets.

CONCLUSION

The review highlights the crucial role of m6A modification in female reproductive development and related diseases. It underscores the need for further research to explore innovative diagnostic and therapeutic strategies for reproductive disorders, leveraging the insights gained from understanding m6A modification's impact on reproductive health.

Morphine-Driven m6A Epitranscriptomic Neuroadaptations in Primary Cortical Cultures

Opioid overdose is the leading cause of accidental death in the United States and remains a major public health concern, despite significant resources aimed at combating opioid misuse. Neurobiological research to elucidate molecular and cellular consequences of opioid exposure is required to define avenues to explore for reversal of opioid-induced neuroadaptations. Opioids impart well-documented regulation of the transcriptome and epigenetic modifications in the brain, but opioid-induced epitranscriptomic posttranscriptional regulation of RNA is vastly understudied. N6-methyladenosine (m6A) RNA methylation is significantly enriched in the brain and involved in learning, memory, and reward. m6A modifications have not been studied in opioid use disorder, despite being the most common RNA modification. We detected significant regulation of m6A-modifying enzymes in rat primary cortical cultures following morphine treatment, including AlkB Homolog 5 (Alkbh5). The m6a demethylase ALKBH5 functions as an m6A eraser, removing m6A modifications from mRNA. We hypothesized that chronic opioid treatment regulates m6A modifications through modulation of Alkbh5 and profiled m6A modifications in primary cortical cultures following chronic morphine treatment and Alkbh5 knock-down. We observed differential regulation of m6A modifications for a common set of transcripts following morphine or Alkbh5 knock-down, and the two treatments elicited concordant m6A epitranscriptomic profiles, suggesting that a subset of morphine-driven m6A modifications may be mediated through downregulation of Alkbh5 in cortical cultures. Gene Ontology terms of commonly regulated transcripts included serotonin secretion, synapse disassembly, neuron remodeling, and immune response. Thus, we conclude that morphine can drive epitranscriptomic changes, a subset of which may occur in an Alkbh5-dependent manner.

Epigenetics behind CD8+ T cell activation and exhaustion

CD8+ T cells play a critical role in specific immunity. In recent years, cell therapy has been emerging rapidly. The specific cytotoxic capabilities of these cells enable them to precisely identify and kill cells presenting specific antigens. This has demonstrated promise in the treatment of autoimmune diseases and cancers, with wide-ranging applications and value. However, in some diseases, such as tumors and chronic infections, T cells may adopt an exhausted phenotype, resulting in a loss of cytotoxicity and limiting their further application. Epigenetics plays a significant role in the differentiation and regulation of gene expression in cells. There is extensive evidence indicating that epigenetic remodeling plays an important role in T cell exhaustion. Therefore, further understanding its role in CD8+ T cell function can provide insights into the programmatic regulation of CD8+ T cells from a genetic perspective and overcome these diseases. We attempted to describe the relationship between the activation, function, and exhaustion mechanisms of CD8+ T cells, as well as epigenetics. This understanding makes it possible for us to address the aforementioned issues.

AKT kinases as therapeutic targets

AKT, or protein kinase B, is a central node of the PI3K signaling pathway that is pivotal for a range of normal cellular physiologies that also underlie several pathological conditions, including inflammatory and autoimmune diseases, overgrowth syndromes, and neoplastic transformation. These pathologies, notably cancer, arise if either the activity of AKT or its positive or negative upstream or downstream regulators or effectors goes unchecked, superimposed on by its intersection with a slew of other pathways. Targeting the PI3K/AKT pathway is, therefore, a prudent countermeasure. AKT inhibitors have been tested in many clinical trials, primarily in combination with other drugs. While some have recently garnered attention for their favorable profile, concern over resistance and off-target effects have continued to hinder their widespread adoption in the clinic, mandating a discussion on alternative modes of targeting. In this review, we discuss isoform-centric targeting that may be more effective and less toxic than traditional pan-AKT inhibitors and its significance for disease prevention and treatment, including immunotherapy. We also touch on the emerging mutant- or allele-selective covalent allosteric AKT inhibitors (CAAIs), as well as indirect, novel AKT-targeting approaches, and end with a briefing on the ongoing quest for more reliable biomarkers predicting sensitivity and response to AKT inhibitors, and their current state of affairs.

Virus-modified paraspeckle-like condensates are hubs for viral RNA processing and their formation drives genomic instability

The nucleus is a highly organised yet dynamic environment containing distinct membraneless nuclear bodies. This spatial separation enables a subset of components to be concentrated within biomolecular condensates, allowing efficient and discrete processes to occur which regulate cellular function. One such nuclear body, paraspeckles, are comprised of multiple paraspeckle proteins (PSPs) built around the architectural RNA, NEAT1_2. Paraspeckle function is yet to be fully elucidated but has been implicated in a variety of developmental and disease scenarios. We demonstrate that Kaposi's sarcoma-associated herpesvirus (KSHV) drives formation of structurally distinct paraspeckles with a dramatically increased size and altered protein composition that are required for productive lytic replication. We highlight these virus-modified paraspeckles form adjacent to virus replication centres, potentially functioning as RNA processing hubs for viral transcripts during infection. Notably, we reveal that PSP sequestration into virus-modified paraspeckles result in increased genome instability during both KSHV and Epstein Barr virus (EBV) infection, implicating their formation in virus-mediated tumourigenesis.

RNA modifications: emerging players in the regulation of reproduction and development

The intricate world of RNA modifications, collectively termed the epitranscriptome, covers over 170 identified modifications and impacts RNA metabolism and, consequently, almost all biological processes. In this review, we focus on the regulatory roles and biological functions of a panel of dominant RNA modifications (including m 6A, m 5C, Ψ, ac 4C, m 1A, and m 7G) on three RNA types-mRNA, tRNA, and rRNA-in mammalian development, particularly in the context of reproduction as well as embryonic development. We discuss in detail how those modifications, along with their regulatory proteins, affect RNA processing, structure, localization, stability, and translation efficiency. We also highlight the associations among dysfunctions in RNA modification-related proteins, abnormal modification deposition and various diseases, emphasizing the roles of RNA modifications in critical developmental processes such as stem cell self-renewal and cell fate transition. Elucidating the molecular mechanisms by which RNA modifications influence diverse developmental processes holds promise for developing innovative strategies to manage developmental disorders. Finally, we outline several unexplored areas in the field of RNA modification that warrant further investigation.

METTL14 suppresses the expression of YAP1 and the stemness of triple-negative breast cancer

BACKGROUND

Triple-negative breast cancer (TNBC) has pronounced stemness that is associated with relapse. N6-methyladenosine (m6A) plays a crucial role in shaping cellular behavior by modulating transcript expression. However, the role of m6A in TNBC stemness, as well as the mechanisms governing its abundance, has yet to be elucidated.

METHODS

We analyzed proteomic and transcriptomic data derived from breast cancer cohorts, with an emphasis on m6A regulators. To unravel the role of m6A in TNBC, we employed RNA sequencing, methylated RNA immunoprecipitation sequencing, RNA immunoprecipitation, chromatin immunoprecipitation, and luciferase reporter assays with mesenchymal stem-like (MSL) TNBC models. The clinical relevance was validated using human tissue microarrays and publicly accessible databases.

RESULTS

Our findings indicate that the global level of m6A modification in MSL TNBC is downregulated primarily due to the loss of methyltransferase-like 14 (METTL14). The diminished m6A modification is crucial for the maintenance of TNBC stemness, as it increases the expression of yes-associated protein 1 (YAP1) by blocking YTH domain-containing family protein 2 (YTHDF2)-mediated transcript decay, thereby promoting the activation of Hippo-independent YAP1 signaling. YAP1 is essential for sustaining the stemness regulated by METTL14. Furthermore, we demonstrated that the loss of METTL14 expression results from lysine-specific demethylase 1 (LSD1)-mediated removal of histone H3 lysine 4 methylation at the promoter region, which is critical for LSD1-driven stemness in TNBC.

CONCLUSION

These findings present an epi-transcriptional mechanism that maintains Hippo-independent YAP1 signaling and plays a role in preserving the undifferentiated state of TNBC, which indicates the potential for targeting the LSD1-METTL14 axis to address TNBC stemness.

The m6A-independent role of epitranscriptomic factors in cancer

Protein function alteration and protein mislocalization are cancer hallmarks that drive oncogenesis. N6-methyladenosine (m6A) deposition mediated by METTL3, METTL16, and METTL5 together with the contribution of additional subunits of the m6A system, has shown a dramatic impact on cancer development. However, the cellular localization of m6A proteins inside tumor cells has been little studied so far. Interestingly, recent evidence indicates that m6A methyltransferases are not always confined to the nucleus, suggesting that epitranscriptomic factors may also have multiple oncogenic roles beyond m6A that still represent an unexplored field. To date novel epigenetic drugs targeting m6A modifiers, such as METTL3 inhibitors, are entering into clinical trials, therefore, the study of the potential onco-properties of m6A effectors beyond m6A is required. Here we will provide an overview of methylation-independent functions of the m6A players in cancer, describing the molecular mechanisms involved and the future implications for therapeutics.

The mRNA N6-Methyladenosine Response to Dehydration in Xenopus laevis

The African clawed frog, Xenopus laevis, exhibits remarkable adaptations to survive in its arid habitat, including behavioral and metabolic changes during periods of drought. During extreme dehydration, X. laevis undergoes estivation, a state characterized by increased urea and ammonia levels, depression of the metabolic rate, and tissue hypoxia. To understand the molecular mechanisms underlying these adaptations, we investigated the potential role of N6-methyladenosine (m6A), a widespread mRNA modification, in X. laevis during extreme dehydration. We analyzed the protein levels of key components in the m6A pathway, including writers (METTL3, METTL14, and WTAP), erasers (ALKBH5 and FTO), and readers (SRSF3, YTHDF1, YTHDF2, YTHDF3, and eIF3a), in the liver and kidneys of control frogs and frogs that had lost 35 ± 0.93% of their total body water. The relative protein levels generally decreased or remained unchanged, with the exception of YTHDF3, which depicted a protein level increase in the liver. Notable changes included eIF3a, which was downregulated by 26 ± 8% and 80 ± 8% in the dehydrated liver and kidney tissues, respectively. Additionally, the total m6A increased by 353 ± 30% and 177 ± 17% in dehydrated liver and kidney RNA samples, respectively. This study highlights the importance of epigenetic mechanisms in stress tolerance and provides a foundation for further exploration of the role of epigenetics in dehydration tolerance.

Decoding the interplay between m6A modification and stress granule stability by live-cell imaging

N6-methyladenosine (m6A)-modified mRNAs and their cytoplasmic reader YTHDFs are colocalized with stress granules (SGs) under stress conditions, but the interplay between m6A modification and SG stability remains unclear. Here, we presented a spatiotemporal m6A imaging system (SMIS) that can monitor the m6A modification and the translation of mRNAs with high specificity and sensitivity in a single live cell. SMIS showed that m6A-modified reporter mRNAs dynamically enriched into SGs under arsenite stress and gradually partitioned into the cytosol as SG disassembled. SMIS revealed that knockdown of YTHDF2 contributed to SG disassembly, resulting in the fast redistribution of mRNAs from SGs and rapid recovery of stalled translation. The mechanism is that YTHDF2 can regulate SG stability through the interaction with G3BP1 in m6A-modified RNA-dependent manner. Our results suggest a mechanism for the interplay between m6A modification and SG through YTHDF2 regulation.

Dynamic multilayered control of m6A RNA demethylase activity

Similar to DNA and histone, RNA can also be methylated. In its most common form, a N6-methyladenosine (m6A) chemical modification is introduced into nascent messenger ribonucleic acid (mRNA) by a specialized methyltransferase complex and removed by the RNA demethylases, Fat mass and obesity-associated (FTO), and ALKBH5. The fate of m6A-marked mRNA is uniquely diverse, ranging from degradation to stabilization/translation, which has been suggested to be largely dependent on its interaction with the family of YT521-B homology (YTH) domain-containing proteins. Here, we highlight a series of control levers that impinge on the RNA demethylases. We present evidence to indicate that intermediary metabolism and various posttranslation modifications modulate the activity, stability, and the subcellular localization of FTO and ALKBH5, further dispelling the notion that m6A methylation is not a dynamic process. We also discuss how examination of these underappreciated regulatory nodes adds a more nuanced view of the role of FTO and ALKBH5 and should guide their study in cancer and nonmalignant conditions alike.

Structural insights into the agonist selectivity of the adenosine A3 receptor

Adenosine receptors play pivotal roles in physiological processes. Adenosine A3 receptor (A3R), the most recently identified adenosine receptor, is expressed in various tissues, exhibiting important roles in neuron, heart, and immune cells, and is often overexpressed in tumors, highlighting the therapeutic potential of A3R-selective agents. Recently, we identified RNA-derived N6-methyladenosine (m6A) as an endogenous agonist for A3R, suggesting the relationship between RNA-derived modified adenosine and A3R. Despite extensive studies on the other adenosine receptors, the selectivity mechanism of A3R, especially for A3R-selective agonists such as m6A and namodenoson, remained elusive. Here, we identify tRNA-derived N6-isopentenyl adenosine (i6A) as an A3R-selective ligand via screening of modified nucleosides against the adenosine receptors. Like m6A, i6A is found in the human body and may be an endogenous A3R ligand. Our cryo-EM analyses elucidate the A3R-Gi complexes bound to adenosine, 5'-N-ethylcarboxamidoadenosine (NECA), m6A, i6A, and namodenoson at overall resolutions of 3.27 Å (adenosine), 2.86 Å (NECA), 3.19 Å (m6A), 3.28 Å (i6A), and 3.20 Å (namodenoson), suggesting the selectivity and activation mechanism of A3R. We further conduct structure-guided engineering of m6A-insensitive A3R, which may aid future research targeting m6A and A3R, providing a molecular basis for future drug discovery.

KHSRP Stabilizes m6A-Modified Transcripts to Activate FAK Signaling and Promote Pancreatic Ductal Adenocarcinoma Progression

N 6-Methyladenosine (m6A) is the most prevalent RNA modification and is associated with various biological processes. Proteins that function as readers and writers of m6A modifications have been shown to play critical roles in human malignancies. Here, we identified KH-type splicing regulatory protein (KHSRP) as an m6A binding protein that contributes to the progression of pancreatic ductal adenocarcinoma (PDAC). High KHSRP levels were detected in PDAC and predicted poor patient survival. KHSRP deficiency suppressed PDAC growth and metastasis in vivo. Mechanistically, KHSRP recognized and stabilized FAK pathway mRNAs, including MET, ITGAV, and ITGB1, in an m6A-dependent manner, which led to activation of downstream FAK signaling that promoted PDAC progression. Targeting KHSRP with a PROTAC showed promising tumor suppressive effects in mouse models, leading to prolonged survival. Together, these findings indicate that KHSRP mediates FAK pathway activation in an m6A-dependent manner to support PDAC growth and metastasis, highlighting the potential of KHSRP as a therapeutic target in pancreatic cancer. Significance: KHSRP is a m6A-binding protein that stabilizes expression of FAK pathway mRNAs and that can be targeted to suppress FAK signaling and curb pancreatic ductal adenocarcinoma progression.

m6A modification of mutant huntingtin RNA promotes the biogenesis of pathogenic huntingtin transcripts

In Huntington's disease (HD), aberrant processing of huntingtin (HTT) mRNA produces HTT1a transcripts that encode the pathogenic HTT exon 1 protein. The mechanisms behind HTT1a production are not fully understood. Considering the role of m6A in RNA processing and splicing, we investigated its involvement in HTT1a generation. Here, we show that m6A methylation is increased before the cryptic poly(A) sites (IpA1 and IpA2) within the huntingtin RNA in the striatum of Hdh+/Q111 mice and human HD samples. We further assessed m6A's role in mutant Htt mRNA processing by pharmacological inhibition and knockdown of METTL3, as well as targeted demethylation of Htt intron 1 using a dCas13-ALKBH5 system in HD mouse cells. Our data reveal that Htt1a transcript levels are regulated by both METTL3 and the methylation status of Htt intron 1. They also show that m6A methylation in intron 1 depends on expanded CAG repeats. Our findings highlight a potential role for m6A in aberrant splicing of Htt mRNA.

RNA modification in normal hematopoiesis and hematologic malignancies

N6-methyladenosine (m6A) is the most abundant RNA modification in eukaryotic cells. Previous studies have shown that m6A plays a critical role under both normal physiological and pathological conditions. Hematopoiesis and differentiation are highly regulated processes, and recent studies on m6A mRNA methylation have revealed how this modification controls cell fate in both normal and malignant hematopoietic states. However, despite these insights, a comprehensive understanding of its complex roles between normal hematopoietic development and malignant hematopoietic diseases remains elusive. This review first provides an overview of the components and biological functions of m6A modification regulators. Additionally, it highlights the origin, differentiation process, biological characteristics, and regulatory mechanisms of hematopoietic stem cells, as well as the features, immune properties, and self-renewal pathways of leukemia stem cells. Last, the article systematically reviews the latest research advancements on the roles and mechanisms of m6A regulatory factors in normal hematopoiesis and related malignant diseases. More importantly, this review explores how targeting m6A regulators and various signaling pathways could effectively intervene in the development of leukemia, providing new insights and potential therapeutic targets. Targeting m6A modification may hold promise for achieving more precise and effective leukemia treatments.

YTHDC1 Regulates the Migration, Invasion, Proliferation, and Apoptosis of Rheumatoid Fibroblast-Like Synoviocytes

Background

Rheumatoid arthritis (RA), a chronic autoimmune condition, is characterized by persistent synovial inflammation, bone degradation, and progressive joint deterioration. Despite considerable research efforts, the precise molecular mechanism underlying RA remains elusive. This investigation aims to elucidate the potential role and molecular mechanism of N6-methyladenosine (m6A) methylation regulators in the pathogenesis of RA.

Methods

In this study, we employed bioinformatics tools to elucidate the association between RA and m6A modifications, aiming to identify potential biological markers. We extracted datasets GSE12021, GSE55235, and GSE55457 from the Gene Expression Omnibus (GEO) database for comprehensive analysis. Utilizing differential expression analysis, protein-protein interaction (PPI) analysis, and single-cell sequencing techniques, we identified pivotal hub genes implicated in the pathogenesis of RA. Subsequently, we assessed the correlation between these hub genes and the pathogenesis of RA using Gene Set Enrichment Analysis (GSEA). Both in vivo and in vitro experiments were performed to confirm the expression and functional roles of the identified key hub gene in RA.

Results

Differential expression analysis, PPI analysis, and single-cell analysis identified three key hub genes (YTHDC1, YTHDC2, and YTHDF2) associated with RA. GSEA results further revealed that these genes are enriched in pathways associated with inflammatory responses. Subsequent correlation analysis demonstrated a significant negative correlation between YTHDC1 expression and CD8+ T cell levels. Notably, the gene and protein expression levels of YTHDC1 and YTHDF2 were significantly reduced in the synovial tissue of RA patients. Furthermore, silencing YTHDC1 in fibroblast-like synoviocytes (FLSs) significantly inhibited their migration, invasion, proliferation, and induced apoptosis.

Conclusion

YTHDC1 may potentially be involved in the pathogenesis of RA through its regulation of migration, invasion, proliferation, and apoptosis in FLSs.

METTL3-STAT5B interaction facilitates the co-transcriptional m6A modification of mRNA to promote breast tumorigenesis

Enhanced expression of methyltransferase-like 3 (METTL3) promotes the m6A modification of specific mRNAs, contributing to breast tumorigenesis. While the mRNA substrates targeted by METTL3 are well characterized, the factors dictating the selection of these specific mRNA remain elusive. This study aimed to examine the regulatory role of the transcription factor STAT5B in METTL3-induced m6A modification. METTL3 specifically interacts with STAT5B in response to mitogenic stimulation by epidermal growth factor (EGF). Chromatin immunoprecipitation and CRISPR/Cas9 mutagenesis showed that STAT5B recruits METTL3 to gene promoters like CCND1, where METTL3 interacts with RPB1, dependent on CDK9-mediated RPB1 (Ser2) phosphorylation during transcription elongation. Inhibition and depletion of either STAT5B or CDK9 prevented the EGF-induced m6A modification of CCND1. The translation efficiency of CCND1 was increased following m6A modification, thereby increasing cell proliferation. STAT5B facilitated METTL3-induced tumor formation by increasing CCND1 expression in an orthotopic mouse model. In clinical context, a positive correlation was observed between p-STAT5B and METTL3 expression in high-grade breast tumors. This study elucidates a novel mechanism that underlies the specificity of m6A modification in breast cancer cells, thereby underscoring its potential therapeutic value.

Regulation of m6A (N6-Methyladenosine) methylation modifiers in solid cancers

Solid cancers constitute a tremendous burden on global healthcare, requiring a deeper understanding of the molecular mechanisms underlying cancer development and progression. Epigenetic changes, notably N6-methyladenosine (m6A) RNA methylation, have emerged as important contributors to the biology of solid tumors in recent years. This epigenetic mark dynamically affects gene expression at the post-transcriptional level and modulates a variety of cellular processes, making it a focus of research in the context of solid tumors. m6A modification patterns are dysregulated in a variety of solid cancers, including ovarian, breast, lung, colorectal, pancreatic, and others. This dysregulated m6A landscape has been shown to induce significant changes in the expression of oncogenes, tumor suppressors, and genes involved in cancer stem cells, metastasis, and treatment resistance. In solid tumors, the interaction of m6A "writers" (e.g., METTL3, METTL14, and others), "erasers" (e.g., ALKBH5, FTO), and "readers" (e.g., members of YTHDF proteins and others) delicately changes the m6A methylome. Targeting m6A regulators as a potential therapeutic method to control gene expression and prevent tumor development seems a novel strategy. To enhance treatment results, advances in this area of research have led to the development of targeted treatments aiming at restoring or altering m6A alteration patterns in solid tumors.

R-loops' m6A modification and its roles in cancers

R-loops are three-stranded nucleic acid structures composed of an RNA-DNA hybrid and a displaced DNA strand. They are widespread and play crucial roles in regulating gene expression, DNA replication, and DNA and histone modifications. However, their regulatory mechanisms remain unclear. As R-loop detection technology advances, changes in R-loop levels have been observed in cancer models, often associated with transcription-replication conflicts and genomic instability. N6-methyladenosine (m6A) is an RNA epigenetic modification that regulates gene expression by affecting RNA localization, splicing, translation, and degradation. Upon reviewing the literature, we found that R-loops with m6A modifications are implicated in tumor development and progression. This article summarizes the molecular mechanisms and detection methods of R-loops and m6A modifications in gene regulation, and reviews recent research on m6A-modified R-loops in oncology. Our goal is to provide new insights into the origins of genomic instability in cancer and potential strategies for targeted therapy.

YTHDC1-mediated microRNA maturation is essential for hematopoietic stem cells maintenance

YTHDC1, a reader of N6-methyladenosine (m6A) modifications on RNA, is posited to exert significant influence over RNA metabolism. Despite its recognized importance, the precise function and underlying mechanisms of YTHDC1 in the preservation of normal hematopoietic stem cell (HSCs) homeostasis remain elusive. Here, we investigated the role of YTHDC1 in normal hematopoiesis and HSCs maintenance in vivo. Utilizing conditional Ythdc1 knockout mice and Ythdc1/Mettl3 double knockout mice, we demonstrated that YTHDC1 is required for HSCs maintenance and self-renewal by regulating microRNA maturation. YTHDC1 deficiency resulted in HSCs apoptosis. Furthermore, we uncovered that YTHDC1 interacts with HP1BP3, a nuclear RNA binding protein involved in microRNA maturation. Deletion of YTHDC1 brought about significant alterations in microRNA levels. However, over-expression of mir-125b, mir-99b, and let-7e partially rescued the functional defect of YTHDC1-null HSCs. Taken together, these findings indicated that the nuclear protein YTHDC1-HP1BP3-microRNA maturation axis is essential for the long-term maintenance of HSCs.

The Role of N6-methyladenosine Modification in Gametogenesis and Embryogenesis: Impact on Fertility

The most common epigenetic modification of messenger RNAs (mRNAs) is N6-methyladenosine (m6A), which is mainly located near the 3' untranslated region of mRNAs, near the stop codons, and within internal exons. The biological effect of m6A is dynamically modulated by methyltransferases (writers), demethylases (erasers), and m6A-binding proteins (readers). By controlling post-transcriptional gene expression, m6A has a significant impact on numerous biological functions, including RNA transcription, translation, splicing, transport, and degradation. Hence, m6A influences various physiological and pathological processes, such as spermatogenesis, oogenesis, embryogenesis, placental function, and human reproductive system diseases. During gametogenesis and embryogenesis, genetic material undergoes significant changes, including epigenomic modifications such as m6A. From spermatogenesis and oogenesis to the formation of an oosperm and early embryogenesis, m6A changes occur at every step. m6A abnormalities can lead to gamete abnormalities, developmental delays, impaired fertilization, and maternal-to-zygotic transition blockage. Both mice and humans with abnormal m6A modifications exhibit impaired fertility. In this review, we discuss the dynamic biological effects of m6A and its regulators on gamete and embryonic development and review the possible mechanisms of infertility caused by m6A changes. We also discuss the drugs currently used to manipulate m6A and provide prospects for the prevention and treatment of infertility at the epigenetic level.

Nuclear retention coupled with sequential polyadenylation dictates post-transcriptional m6A modification in the nucleus

N6-methyladenosine (m6A) modification is deemed to be co-transcriptionally installed on pre-mRNAs, thereby influencing various downstream RNA metabolism events. However, the causal relationship between m6A modification and RNA processing is often unclear, resulting in premature or even misleading generalizations on the function of m6A modification. Here, we develop 4sU-coupled m6A-level and isoform-characterization sequencing (4sU-m6A-LAIC-seq) and 4sU-GLORI to quantify the m6A levels for both newly synthesized and steady-state RNAs at transcript and single-base-resolution levels, respectively, which enable dissecting the relationship between m6A modification and alternative RNA polyadenylation. Unexpectedly, our results show that many m6A addition events occur post-transcriptionally, especially on transcripts with high m6A levels. Importantly, we find higher m6A levels on shorter 3' UTR isoforms, which likely result from sequential polyadenylation of longer 3' UTR isoforms with prolonged nuclear dwelling time. Therefore, m6A modification can also take place post-transcriptionally to intimately couple with other key RNA metabolism processes to establish and dynamically regulate epi-transcriptomics in mammalian cells.

Nuclear mRNA decay: regulatory networks that control gene expression

Proper regulation of mRNA production in the nucleus is critical for the maintenance of cellular homoeostasis during adaptation to internal and environmental cues. Over the past 25 years, it has become clear that the nuclear machineries governing gene transcription, pre-mRNA processing, pre-mRNA and mRNA decay, and mRNA export to the cytoplasm are inextricably linked to control the quality and quantity of mRNAs available for translation. More recently, an ever-expanding diversity of new mechanisms by which nuclear RNA decay factors finely tune the expression of protein-encoding genes have been uncovered. Here, we review the current understanding of how mammalian cells shape their protein-encoding potential by regulating the decay of pre-mRNAs and mRNAs in the nucleus.

RNA modifications in the progression of liver diseases: from fatty liver to cancer

Non-alcoholic fatty liver disease (NAFLD) has emerged as a prominent global health concern associated with high risk of metabolic syndrome, and has impacted a substantial segment of the population. The disease spectrum ranges from simple fatty liver to non-alcoholic steatohepatitis (NASH), which can progress to cirrhosis and hepatocellular carcinoma (HCC) and is increasingly becoming a prevalent indication for liver transplantation. The existing therapeutic options for NAFLD, NASH, and HCC are limited, underscoring the urgent need for innovative treatment strategies. Insights into gene expression, particularly RNA modifications such as N6 methyladenosine (m6A), hold promising avenues for interventions. These modifications play integral roles in RNA metabolism and cellular functions, encompassing the entire NAFLD-NASH-HCC progression. This review will encompass recent insights on diverse RNA modifications, including m6A, pseudouridine (ψ), N1-methyladenosine (m1A), and 5-methylcytidine (m5C) across various RNA species. It will uncover their significance in crucial aspects such as steatosis, inflammation, fibrosis, and tumorigenesis. Furthermore, prospective research directions and therapeutic implications will be explored, advancing our comprehensive understanding of the intricate interconnected nature of these pathological conditions.

N6-methyladenosine promotes TNF mRNA degradation in CD4+ T lymphocytes

N6-methyladenosine (m6A) is a RNA modification that can regulate post-transcriptional processes including RNA stability, translation, splicing, and nuclear export. In CD4+ lymphocytes, m6A modifications have been demonstrated to play a role in early differentiation processes. The role of m6A in CD4+ T cell activation and effector function remains incompletely understood. To assess the role of m6A in CD4+ T lymphocyte activation and function, we assessed the transcriptome-wide m6A landscape of human primary CD4+ T cells by methylated RNA immunoprecipitation sequencing. Stimulation of the T cells impacted the m6A pattern of hundreds of transcripts including tumor necrosis factor (TNF). m6A methylation was increased on TNF messenger RNA (mRNA) after activation, predominantly in the 3' untranslated region of the transcript. Manipulation of m6A levels in primary human T cells, the directly affected the expression of TNF. Furthermore, we identified that the m6A reader protein YTHDF2 binds m6A-methylated TNF mRNA, and promotes its degradation. Taken together, this study demonstrates that TNF expression in CD4+ T lymphocytes is regulated via m6A and YTHDF2, thereby providing novel insight into the regulation of T cell effector functions.

Regulatory roles of N6-methyladenosine (m6A) methylation in RNA processing and non-communicable diseases

Post-transcriptional RNA modification is an emerging epigenetic control mechanism in cells that is important in many different cellular and organismal processes. N6-methyladenosine (m6A) is one of the most prevalent, prolific, and ubiquitous internal transcriptional alterations in eukaryotic mRNAs, making it an important topic in the field of Epigenetics. m6A methylation acts as a dynamical regulatory process that regulates the activity of genes and participates in multiple physiological processes, by supporting multiple aspects of essential mRNA metabolic processes, including pre-mRNA splicing, nuclear export, translation, miRNA synthesis, and stability. Extensive research has linked aberrations in m6A modification and m6A-associated proteins to a wide range of human diseases. However, the impact of m6A on mRNA metabolism and its pathological connection between m6A and other non-communicable diseases, including cardiovascular disease, neurodegenerative disorders, liver diseases, and cancer remains in fragmentation. Here, we review the existing understanding of the overall role of mechanisms by which m6A exerts its activities and address new discoveries that highlight m6A's diverse involvement in gene expression regulation. We discuss m6A deposition on mRNA and its consequences on degradation, translation, and transcription, as well as m6A methylation of non-coding chromosomal-associated RNA species. This study could give new information about the molecular process, early detection, tailored treatment, and predictive evaluation of human non-communicable diseases like cancer. We also explore more about new data that suggests targeting m6A regulators in diseases may have therapeutic advantages.

CRISPR/dCas13(Rx) Derived RNA N6-methyladenosine (m6A) Dynamic Modification in Plant

N6-methyladenosine (m6A) is the most prevalent internal modification of mRNA and plays an important role in regulating plant growth. However, there is still a lack of effective tools to precisely modify m6A sites of individual transcripts in plants. Here, programmable m6A editing tools are developed by combining CRISPR/dCas13(Rx) with the methyltransferase GhMTA (Targeted RNA Methylation Editor, TME) or the demethyltransferase GhALKBH10 (Targeted RNA Demethylation Editor, TDE). These editors enable efficient deposition or removal of m6A modifications at targeted sites of endo-transcripts GhECA1 and GhDi19 within a broad editing window ranging from 0 to 46 nt. TDE editor significantly decreases m6A levels by 24%-76%, while the TME editor increases m6A enrichment, ranging from 1.37- to 2.51-fold. Furthermore, installation and removal of m6A modifications play opposing roles in regulating GhECA1 and GhDi19 mRNA transcripts, which may be attributed to the fact that their m6A sites are located in different regions of the genes. Most importantly, targeting the GhDi19 transcript with TME editor plants results in a significant increase in root length and enhanced drought resistance. Collectively, these m6A editors can be applied to study the function of specific m6A modifications and have the potential for future applications in crop improvement.

Dynamic RNA methylation modifications and their regulatory role in mammalian development and diseases

Among over 170 different types of chemical modifications on RNA nucleobases identified so far, RNA methylation is the major type of epitranscriptomic modifications existing on almost all types of RNAs, and has been demonstrated to participate in the entire process of RNA metabolism, including transcription, pre-mRNA alternative splicing and maturation, mRNA nucleus export, mRNA degradation and stabilization, mRNA translation. Attributing to the development of high-throughput detection technologies and the identification of both dynamic regulators and recognition proteins, mechanisms of RNA methylation modification in regulating the normal development of the organism as well as various disease occurrence and developmental abnormalities upon RNA methylation dysregulation have become increasingly clear. Here, we particularly focus on three types of RNA methylations: N6-methylcytosine (m6A), 5-methylcytosine (m5C), and N7-methyladenosine (m7G). We summarize the elements related to their dynamic installment and removal, specific binding proteins, and the development of high-throughput detection technologies. Then, for a comprehensive understanding of their biological significance, we also overview the latest knowledge on the underlying mechanisms and key roles of these three mRNA methylation modifications in gametogenesis, embryonic development, immune system development, as well as disease and tumor progression.

Integration of multi-omics summary data reveals the role of N6-methyladenosine in neuropsychiatric disorders

N6-methyladenosine (m6A) methylation regulates gene expression/protein by influencing numerous aspects of mRNA metabolism and contributes to neuropsychiatric diseases. Here, we integrated multi-omics data and genome-wide association study summary data of schizophrenia (SCZ), bipolar disorder (BP), attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), major depressive disorder (MDD), Alzheimer's disease (AD), and Parkinson's disease (PD) to reveal the role of m6A in neuropsychiatric disorders by using transcriptome-wide association study (TWAS) tool and Summary-data-based Mendelian randomization (SMR). Our investigation identified 86 m6A sites associated with seven neuropsychiatric diseases and then revealed 7881 associations between m6A sites and gene expressions. Based on these results, we discovered 916 significant m6A-gene associations involving 82 disease-related m6A sites and 606 genes. Further integrating the 58 disease-related genes from TWAS and SMR analysis, we obtained 61, 8, 7, 3, and 2 associations linking m6A-disease, m6A-gene, and gene-disease for SCZ, BP, AD, MDD, and PD separately. Functional analysis showed the m6A mapped genes were enriched in "response to stimulus" pathway. In addition, we also analyzed the effect of gene expression on m6A and the post-transcription effect of m6A on protein. Our study provided new insights into the genetic component of m6A in neuropsychiatric disorders and unveiled potential pathogenic mechanisms where m6A exerts influences on disease through gene expression/protein regulation.

m6A RNA methylation modification is involved in the disease course of heart failure

We explored N6-methyladenosine (m6A) RNA methylation as one of the gene regulatory mechanisms in heart failure (HF) biology. Understanding the different physiological mechanisms will facilitate the prevention and individualized treatment of HF. The Gene Expression Omnibus (GEO) database served as the source of the data. In GSE116250, differential analysis between ischemic cardiomyopathy (ICM), dilated cardiomyopathy (DCM) and controls yielded differentially expressed m6A regulators. Differential analysis between HF and controls in GSE131296 identifies m6A-modified genes and then performs enrichment analysis. Protein-protein interaction (PPI) network analysis was performed for the differentially expressed ICM- or DCM-associated genes in GSE116250 and GSE55296, respectively. Finally, the diagnostic genes for ICM and DCM were predicted using receiver operating characteristic (ROC) curve. YTHDC1, HNRNPC and HNRNPA2B1 were significantly downregulated in GSE116250 in DCM and ICM compared with controls. A total of 195 genes were identified in GSE131296 as subject to m6A alteration. These genes may play a role in HF through the MAPK signaling pathway and p53 signaling pathway. PPI network analysis identified CCL5, CXCR4 and CCL2 as key genes for ICM and IL-6 as a key gene for DCM. Through ROC curves, we identified m6A-modified APLP1, KLF2 as potential diagnostic genes for ICM, and m6A-modified FGF7, FREM1 and C14orf132 as potential diagnostic genes for DCM. Our findings support m6A modifying mechanisms in HF etiology that contribute to the treatment of HF. Thus, our data suggest that m6A methylation may be an interesting target for therapeutic intervention.

Epigenetic modifications in hematopoietic ecosystem: a key tuner from homeostasis to acute myeloid leukemia

Hematopoietic stem cells (HSCs) maintain homeostasis in the hematopoietic ecosystem, which is tightly regulated at multiple layers. Acute myeloid leukemia (AML) is a severe hematologic malignancy driven by genetic and epigenetic changes that lead to the transformation of leukemia stem cells (LSCs). Since somatic mutations in DNA methylation-related genes frequently occur in AML, DNA methylation is widely altered and functions as a starting engine for initiating AML. Additionally, RNA modifications, especially N6-methyladenosine (m6A), also play an important role in the generation and maintenance of the hematopoietic ecosystem, and AML development requires reprogramming of m6A modifications to facilitate cells with hallmarks of cancer. Given the complex pathogenesis and poor prognosis of AML, it is important to fully understand its pathogenesis. Here, we mainly focus on DNA methylation and RNA m6A modification in hematopoiesis and AML and summarize recent advances in this field.

Role of RNA modifications in blood development and regeneration

Blood development and regeneration require rapid turnover of cells, and ribonucleic acid (RNA) modifications play a key role in it via regulating stemness and cell fate regulation. RNA modifications affect gene activity via posttranscriptional and translation-mediated mechanisms. Diverse molecular players involved in RNA-modification processes are abundantly expressed by hematopoietic stem cells and lineages. Close to 150 RNA chemical modifications have been reported, but only N6-methyl adenosine (m6A), inosine (I), pseudouridine (Ψ), and m1A-a handful-have been studied in-cell fate regulation. The role of RNA modification in blood diseases and disorders is an emerging field and offers potential for therapeutic interventions. Knowledge of RNA-modification and enzymatic activities could be used to design therapies in the future. Here, we summarized the recent advances in RNA modification and the epitranscriptome field and discussed their regulation of blood development and regeneration.

Reading the m6A-encoded epitranscriptomic information in development and diseases

N6-methyladenosine (m6A) represents the most prevalent internal and reversible modification on RNAs. Different cell types display their unique m6A profiles, which are determined by the functions of m6A writers and erasers. M6A modifications lead to different outcomes such as decay, stabilization, or transport of the RNAs. The m6A-encoded epigenetic information is interpreted by m6A readers and their interacting proteins. M6A readers are essential for different biological processes, and the defects in m6A readers have been discovered in diverse diseases. Here, we review the latest advances in the roles of m6A readers in development and diseases. These recent studies not only highlight the importance of m6A readers in regulating cell fate transitions, but also point to the potential application of drugs targeting m6A readers in diseases.

Development and validation of a 6-gene signature derived from RNA modification-associated genes for the diagnosis of Acute Stanford Type A Aortic Dissection

Background

Acute Stanford Type A Aortic Dissection (ATAAD) is a critical medical emergency characterized by significant morbidity and mortality. This study aims to identify specific gene expression patterns and RNA modification associated with ATAAD.

Methods

The GSE153434 dataset was obtained from the Gene Expression Omnibus (GEO) database. Differential expression analysis was conducted to identify differential expression genes (DEGs) associated with ATAAD. To validate the involvement of RNA modification in ATAAD, RNA modification-related genes (M6A, M1A, M5C, APA, A-to-I) were acquired from GeneCards, following by Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis. A gene prediction signature consisting of key genes was established, and Real-time PCR was used to validate the gene expression in clinical samples. The patients were then divided into high and low-risk groups, and subsequent enrichment analysis, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Set Enrichment Analysis (GSEA), Gene Set Variation Analysis (GSVA), and assessments of immune infiltration. A co-expression network analysis (WGCNA) was performed to explore gene-phenotype relationships and identify key genes.

Results

A total of 45 RNA modification genes were acquired. Six gene signatures (YTHDC1, WTAP, CFI, ADARB1, ADARB2, TET3) were developed for ATAAD diagnosis and risk stratification. Enrichment analysis suggested the potential involvement of inflammation and extracellular matrix pathways in the progression of ATAAD. The incorporation of pertinent genes from the GSE147026 dataset into the six-gene signature further validated the model's effectiveness. A significant upregulation in WTAP, ADARB2, and TET3 expression, whereas YTHDC1 exhibited a noteworthy downregulation in the ATAAD group.

Conclusion

Six-gene signature could serve as an efficient model for predicting the diagnosis of ATAAD.

Non-canonical translation in cancer: significance and therapeutic potential of non-canonical ORFs, m6A-modification, and circular RNAs

Translation is a decoding process that synthesizes proteins from RNA, typically mRNA. The conventional translation process consists of four stages: initiation, elongation, termination, and ribosome recycling. Precise control over the translation mechanism is crucial, as dysregulation in this process is often linked to human diseases such as cancer. Recent discoveries have unveiled translation mechanisms that extend beyond typical well-characterized components like the m7G cap, poly(A)-tail, or translation factors like eIFs. These mechanisms instead utilize atypical elements, such as non-canonical ORF, m6A-modification, and circular RNA, as key components for protein synthesis. Collectively, these mechanisms are classified as non-canonical translations. It is increasingly clear that non-canonical translation mechanisms significantly impact the various regulatory pathways of cancer, including proliferation, tumorigenicity, and the behavior of cancer stem cells. This review explores the involvement of a variety of non-canonical translation mechanisms in cancer biology and provides insights into potential therapeutic strategies for cancer treatment.

Interplay of RNA m6A Modification-Related Geneset in Pan-Cancer

Background: N6-methyladenosine (m6A), is the most common modification found in mRNA and lncRNA in higher organisms and plays an important role in physiology and pathology. However, its role in pan-cancer has not been explored. Results: A total of 31 m6A modification regulators, including 12 writers, 2 erasers, and 17 readers are identified in the current study. The functional analysis of the regulators results in the enrichment of processes, primarily related to RNA modification and metabolism, and the PPI network reveals multiple interactions among the regulators. The mRNA expression analysis reveals a high expression for most of the regulators in pan-cancer. Most of the m6A regulators are found to be mutated across the cancers, with ZC3H13, VIRMA, and PRRC2A having a higher frequency rate. Significant correlations of the regulators with clinicopathological parameters, such as age, gender, tumor stage, and grade are identified in pan-cancer. The m6A regulators' expression is found to have significant positive correlations with the miRNAs in pan-cancer. The expression pattern of the m6A regulators is able to classify the tumors into different subclusters as well as into high- and low-risk groups. These tumor groups show differential patterns in terms of their immune cell infiltration, tumor stemness score, genomic heterogeneity score, expression of immune regulatory/checkpoint genes, and correlations between the regulators and the drugs. Conclusions: Our study provide a comprehensive overview of the functional roles, genetic and epigenetic alterations, and prognostic value of the RNA m6A regulators in pan-cancer.

Methyltransferase Like-3-Mediated N6-Methyladenosine Modification of Long Noncoding RNA Hepatocyte Nuclear Factor 1a Antisense RNA 1/Hepatocyte Nuclear Factor 4a Antisense RNA 1 Regulates Cytochrome P450 Enzyme Expression

Interindividual variations in the expression and activity of cytochrome P450 enzymes (CYPs) led to lower therapeutic efficacy or adverse drug events. We previously demonstrated that CYPs are regulated by the long noncoding RNAs (lncRNAs) hepatocyte nuclear factor 1a antisense RNA 1 (HNF1A-AS1) and HNF4A-AS1 via transcription factors (TFs) including hepatocyte nuclear factor 1a (HNF1A), hepatocyte nuclear factor 4a (HNF4A), and pregnane X receptor (PXR). However, the upstream mechanisms regulating HNF1A-AS1 and HNF4A-AS1 are poorly understood. N6-methyladenosine (m6A) is a prevalent epitranscriptomic modification in mammalian RNA. Therefore, the aim of this study was to investigate whether m6A modification regulates the expression of HNF1A-AS1 and HNF4A-AS1 and affects CYP expression in HepG2 and Huh7 cells. The methyltransferase-like 3 (METTL3) inhibitor, STM2457, significantly suppressed the expression of HNF1A-AS1 and induced HNF4A-AS1 expression. Consistent with this, a loss-of-function assay of METTL3 in the cell lines resulted in the downregulation of HNF1A-AS1 and its downstream HNF1A, PXR, and CYPs at the RNA level, as well as the downregulation of some CYPs proteins, and upregulation of HNF4A-AS1. The results of gain-of-function experiments showed the opposite trend. Mechanistically, subsequent RNA stability experiments confirmed that METTL3 affected the stability of both lncRNAs, but in opposite ways; that is, METTL3 reduced HNF1A-AS1 stability and increased HNF4A-AS1 stability. Rescue experiments confirmed that the regulation of METTL3 on TFs and CYPs may require the involvement of these two lncRNAs. Altogether, our study demonstrates that METTL3 is involved in TFs-mediated CYP expression by affecting HNF1A-AS1/HNF4A-AS1 stability. SIGNIFICANCE STATEMENT: Although the impact of long noncoding RNAs (lncRNAs) including hepatocyte nuclear factor 1a antisense RNA 1 (HNF1A-AS1) and hepatocyte nuclear factor 4a antisense RNA 1 (HNF4A-AS1) on the downstream transcription factor (TF) and cytochrome P450 enzyme (CYP) expression is well studied, the upstream regulation of these two lncRNAs by methyltransferase-like 3 (METTL3) remains unexplored. This study reveals that METTL3 is involved in the regulation of lncRNA-TF-CYP expression by affecting the stability of HNF1A-AS1 and HNF4A-AS1 in HepG2 and Huh7 cells.

N6-methyladenosine (m6A) RNA modification in fibrosis and collagen-related diseases

Fibrosis is an abnormal tissue healing process characterized by the excessive accumulation of ECM components, such as COL I and COL III, in response to tissue injury or chronic inflammation. Recent advances in epitranscriptomics have underscored the importance of m6A modification in fibrosis. m6A, the most prevalent modification in eukaryotic RNA, is catalyzed by methyltransferases (e.g., METTL3), removed by demethylases (e.g., FTO), and recognized by reader proteins (e.g., YTHDF1/2). These modifications are crucial in regulating collagen metabolism and associated diseases. Understanding the role of m6A modification in fibrosis and other collagen-related conditions holds promise for developing targeted therapies. This review highlights the latest progress in this area.

N6-Methyladenosine Positively Regulates Coxsackievirus B3 Replication

Enteroviruses such as coxsackievirus B3 are identified as a common cause of viral myocarditis, but the potential mechanism of its replication and pathogenesis are largely unknown. The genomes of a variety of viruses contain N6-methyladenosine (m6A), which plays important roles in virus replication. Here, by using the online bioinformatics tools SRAMP and indirect immunofluorescence assay (IFA), we predict that the CVB3 genome contains m6A sites and found that CVB3 infection could alter the expression and cellular localization of m6A-related proteins. Moreover, we found that 3-deazaadenosine (3-DAA), an m6A modification inhibitor, significantly decreased CVB3 replication. We also observed that the m6A methyltransferases methyltransferase-like protein 3 (METTL3) and METTL14 play positive roles in CVB3 replication, whereas m6A demethylases fat mass and obesity-associated protein (FTO) or AlkB homolog 5 (ALKBH5) have opposite effects. Knockdown of the m6A binding proteins YTH domain family protein 1 (YTHDF1), YTHDF2 and YTHDF3 strikingly decreased CVB3 replication. Finally, the m6A site mutation in the CVB3 genome decreased the replication of CVB3 compared with that in the CVB3 wild-type (WT) strain. Taken together, our results demonstrated that CVB3 could exploit m6A modification to promote viral replication, which provides new insights into the mechanism of the interaction between CVB3 and the host.

An integrated analysis of multiple datasets reveals novel gene signatures in human granulosa cells

Granulosa cells (GCs) play crucial roles in oocyte maturation. Through gap junctions and extracellular vesicles, they mediate the exchange of molecules such as microRNAs and messenger RNAs. Different ovarian cell types exhibit unique gene expression profiles, reflecting their specialized functions and stages. By combining RNA-seq data from various cell types forming the follicle, we aimed at capturing a wide range of expression patterns, offering insights into the functional diversity and complexity of the transcriptome regulation across GCs. Herein, we performed an integrated bioinformatics analysis of RNA sequencing datasets present in public databases, with a unique and standardized workflow., By combining the data from different studies, we successfully increased the robustness and reliability of our findings and discovered novel genes, miRNAs, and signaling pathways associated with GCs function and oocyte maturation. Moreover, our results provide a valuable resource for further wet-lab research on GCs biology and their impact on oocyte development and competence.

Transcriptome-wide m6A methylation profile reveals tissue specific regulatory networks in switchgrass (Panicum virgatum L.) under cadmium stress

The heavy metal cadmium (Cd), known for its high toxicity, poses a grave threat to human health through the food chain. N6-methyladenosine (m6A), the most abundant internal modification, regulates plant adaptation to various adversities, yet the panorama of m6A modifications in switchgrass under cadmium stress remains elusive. This study examines the physiological responses of switchgrass roots and shoots exposed to 50 μM CdCl2, alongside an overview of transcriptome-wide m6A methylation patterns. After cadmium treatment, methylation modifications are primarily enriched near stop codons and the 3'UTR region, with a negative correlation between m6A modification and gene expression levels. In shoots, approximately 58 % of DEGs with m6A modifications show upregulation in expression and decrease in m6A peaks, including zinc transporter 4-like (ZIP4). In roots, about 43 % of DEGs with m6A modifications exhibit downregulation in expression and increase in m6A peaks, such as the ABC transporter family member (ABCG25). We further validate the m6A enrichment, gene expression and mRNA stability of ZIP4 in response to Cd treatment. The results suggest that the negative correlation of m6A enrichment and gene expression is due to altered mRNA stability. Our study establishes an m6A regulatory network governing cadmium transport in switchgrass roots and shoots, offering new avenues for candidate gene manipulation in phytoremediation applications of heavy metal pollution.