The RNA modification landscape in human disease

Altered expression and potential role of N6-methyladenosine mRNA methylation in abdominal aortic aneurysm mouse model

It is an important cause of death in old age to rupture an abdominal aortic aneurysm. The pathogenesis of AAA has not been fully elucidated, and m6A RNA methylation regulators have never been implicated in AAA development. This study aimed to explore the expression profile, potential functions and regulated mechanism of m6A RNA methylation in the abdominal aortic aneurysm mice model. A successful AAA mouse model was established using Ang II. M6A- methylated RNA Immunoprecipitation (MeRIP) sequencing and RNA sequencing were performed to identify the m6A sites in the abdominal aorta walls samples. The expression of m6A methylation regulators was analyzed in the datasets and MeRIP-qPCR was performed to verify the results of MeRIP-sequencing. Bioinformatics analysis was used to evaluate the m6A patterns and indicate the potential signaling pathway. There were 2039 differentially methylated m6A peaks involving 1865 mRNAs in the AAA group relative to the control, of which 1610 peaks in 1466 mRNAs were hypermethylated, and 429 peaks in 410 mRNAs were hypomethylated. The hypermethylated mRNAs in AAA group were primarily enriched in transcription regulation and intercellular signaling, especially the Wnt signaling-associated processes. Hypomethylated m6A sites were mainly enriched in G protein-coupled receptor activity and ion channel activity. MeRIP-qPCR suggested that the sequencing data were reliable and accurate. The mRNA expression of 24 m6A regulators showed no obvious difference between AAA and the control group, but the m6A methylation levels of three components of methyltransferases complex and one 'readers' were significantly increased. Our study suggested an original viewpoint that the m6A modification might be regulated by several unidentified regulation modes or genes in the Ang II-induced AAA mice model, and be closely relevant to the combined effect of m6A methylation modification in the Wnt pathway, G protein-coupled receptor, and ion channel-associated genes, which were worthy of further investigation.

RNA methylated long non-coding RNAs as potential biomarkers for prognosis prediction in patients with lung adenocarcinoma: development of a risk assessment model

INTRODUCTION

Lung adenocarcinoma (LUAD) is the most prevalent form of lung cancer worldwide. Long non-coding RNA (lncRNAs) are non-protein coding RNAs that are involved in lung cancer. This study aimed to develop a lncRNA-based risk assessment model based on RNA methylation to evaluate the prognosis of patients with LUAD.

METHOD

The TCGA-LUAD dataset consisted of 524 primary tumor samples and 59 normal samples, and the validation set (GSE3121011), which included 246 patients with LUAD, was used for this analysis.Pearson's correlation analysis was used to identify lncRNAs associated with RNA methylation in LUAD. Univariate, least absolute shrinkage and selection operators, and multivariate Cox analyses were used to construct the prognostic model. Gene oncology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were used to identify enriched biological processes. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used to visualize the dataset and gene set variation analyses. Kaplan-Meier and decision curve analyses were used to assess the accuracy. qRT-PCR was used to verify the expression of lncRNAs. Invasion and cell scratch assays were conducted to evaluate migration capacity, and colony formation experiments were performed to assess proliferation ability.

RESULT

Ten RNA methylation-associated lncRNAs were identified to construct risk features. According to the risk model, the patients were categorized into low- and high-risk groups, with the latter exhibiting a less favorable prognosis. The expression levels of the lncRNAs exceeded those in lung epithelial cells. After siRNA transfection, the proliferation and migration abilities of the tumor cells were significantly reduced. The risk-scoring model may be a potential indicator for predicting the sensitivity of patients with LUAD to immunotherapy.

CONCLUSION

The model constructed in this study can accurately predict the prognosis of patients with LUAD, and holds promise for future immunotherapies.

The emerging roles of N6-methyladenosine (m6A) deregulation in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is an endocrine metabolic syndrome characterized by ovulation disorders, hyperandrogenemia, and polycystic ovaries, which seriously affect the psychological and physical health of childbearing women. N6-methyladenosine (m6A), as the most common mRNA epigenetic modification in eukaryotes, is vital for developing the female reproductive system and reproductive diseases. In recent years, an increasing number of studies have revealed the mechanisms by which m6A modifications and their related proteins are promoting the development of PCOS, including writers, erasers and readers. In this work, we reviewed the research progress of m6A in the pathophysiological development of PCOS from the starting point of PCOS clinical features, included the recent studies or those with significant findings related to m6A and PCOS, summarized the current commonly used therapeutic methods in PCOS and the possible targeted therapies against the m6A mechanism, and looked forward to future research directions of m6A in PCOS. With the gradual revelation of the m6A mechanism, m6A and its related proteins are expected to become a great field for PCOS treatment.

RNA Modifications in Osteoarthritis: Epitranscriptomic Insights into Pathogenesis and Therapeutic Targets

Osteoarthritis (OA) is a chronic joint disorder characterized by progressive degeneration of articular cartilage, pain, synovial inflammation, and bone remodeling. Post-transcriptional RNA modifications, known as epitranscriptome, are a group of biochemical alterations in the primary RNA transcript that might influence RNA structure, stability, and function. Different kinds of RNA modifications have been recognized, such as methylation, acetylation, pseudouridylation, and phosphorylation. N6-methyladenosine (m6A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), 2'-O-ribose methylation (2'-O-Me), and pseudouridylation (Ψ) are the most prevalent RNA modifications. Recent studies have shown that disruption in these modifications can interfere with gene expression and protein function. Here, we will review all types of RNA modifications and how they contribute to the onset and progression of OA. To the best of our knowledge, this is the first review comprehensively addressing all epitranscriptomic modifications in OA.

Mitochondrial tRNA-specific Taurine Modifications Correlate With Ferroptosis-associated Myocardial Injury

Transfer RNA (tRNA) modifications are crucial for cellular homeostasis and organ function, exhibiting complex stress responses dependent on modification type and location. Ferroptosis, a significant mechanism in ischemic myocardial injury, remains poorly understood at the tRNA epitranscriptome level. In this study, we utilized a liquid chromatography-mass spectrometry (LC-MS) based RNA mapping platform to examine dynamic changes in 40 tRNA modifications within a ferroptosis-associated myocardial injury model. Notably, we identified significant in vitro and in vivo alterations in eight tRNA modifications, particularly a marked downregulation of taurine modifications (τm5U and τm5s2U) at the tRNA anticodon's 34th position, suggesting mitochondrial tRNA (mt-tRNATrp, mt-tRNAGln) reprogramming. Further analysis revealed that taurine modification depletion caused by RSL3 (a ferroptosis inducer) was attributed to taurine consumption and the downregulation of MTO1 and GTPBP3. Depleting these taurine modifications exacerbated ferroptosis in vitro, while restoration protected cardiomyocytes by decreasing reactive oxygen species and lipid peroxides. Silencing of MTO1 and GTPBP3 in H9C2 cells could also enhance RSL3 potency but diminish the protective effect of taurine. Our findings highlight the pivotal role of taurine modifications on mitochondrial tRNAs in determining cellular fate during cardiomyocyte ferroptosis. This study offers new insights into ferroptosis-associated ischemic myocardial injury at the tRNA epitranscriptome level.

The Evolution and Implications of the Inosine tRNA Modification

Ever since the legendary publication by Francis Crick in JMB introducing the wobble hypothesis in 1966, inosine has been a permanent part of molecular biology. This review aims to integrate the rich array of novel insights emerging from subsequent research on the adenine-to-inosine modification of tRNA, with an emphasis on the results obtained during the last 5 years. Both the grand panorama of 4 billion years of evolution of life and the medical implications of defects in inosine modification will be reviewed. The most salient insights are that: (1) inosine at position 34 (the first position in the anticodon) is not universally present in the tree of life; (2) in many bacteria just a single homodimeric enzyme (TadA) is responsible for both tRNA inosine modification and mRNA inosine modification; (3) rapid progress is currently being made both in the molecular understanding of the heterodimeric ADAT2/ADAT3 enzyme responsible for inosine modifications in eukaryotes and in experimental capabilities for monitoring both the cytoplasmic tRNA pool and their modifications; (4) for selected tRNAs, inosine modification at position 37 has been demonstrated but this modification remains under-studied; (5) modification of tRNAs known to contain inosine can be incomplete; (6) the GC content of the T-stem is of great importance for wobble behavior, including wobbling behavior of inosine; and (7) the tRNA inosine modification is of direct relevance to human disease. In summary, research on inosine continues to yield important novel insights.

Comprehensive Analysis of Small RNA Modifications in Arabidopsis thaliana and Their Dynamics During Seed Germination

Background: Small RNA, defined as RNA molecules of less than 200 nucleotides in length, play pivotal regulatory roles in plant growth, development, and environmental stress responses. However, research on modifications in plant small RNA remains limited. Methods: In this study, we developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous detection of 41 RNA modifications, facilitating the systematic qualification and quantification of modifications in plant small RNA. Results: We identified a total of nine modifications, among which N6,N6-dimethyladenosine (m6,6A) is a newly identified modification in plant small RNA. Furthermore, we conducted a quantitative analysis of these modifications in Arabidopsis thaliana during the germination process and observed significant dynamic changes in their abundance from 1 to 5 days post-germination. Notably, the trends in the contents of these modifications exhibited a strong correlation with the reported gene expression levels of the relevant modifying enzymes and demodifying enzymes, suggesting that these modifications may play essential roles during seed germination and are tightly regulated by the genes of the corresponding enzymes. Conclusions: The discovery of these modifications in plant small RNA, coupled with the dynamic changes in their levels during germination, holds great promise for a further understanding of the physiological functions of small RNA modifications and their associated regulatory mechanisms in plant seed germination.

HuMSCs-derived exosomal YBX1 participates in oxidative damage repair in granulosa cells by stabilizing COX5B mRNA in an m5C-dependent manner

Mitochondrial dysfunction and cell senescence are triggered by reactive oxygen species (ROS) in granulosa cells (GCs), leading to premature ovarian insufficiency (POI). Human umbilical cord mesenchymal stem cell-derived exosome (HuMSCs-Ex, H-Ex)-based treatments have been shown to alleviate ROS-induced POI, but knowledge about the underlying therapeutic mechanisms is limited. Here, we observed that the 5-methylcytosine (m5C) RNA methyltransferase tRNA aspartic acid methyltransferase 1 (TRDMT1) promoted the translation of COX subunit 5B (COX5B) in a manner dependent on its catalytic activity and downstream m5C reader Y-box binding protein 1 (YBX1), which was decreased in prematurely senescent GCs but abundant in H-Ex. Mechanistically, YBX1 released by H-Ex recognizes the TRDMT1-mediated m5C modification of COX5B and directly binds to COX5BC-153 via LYS-92, thereby reducing ROS accumulation and improving mitochondrial function in GCs under oxidative stress, providing new insights into the theoretical basis for the great clinical potential of H-Ex in the treatment of POI.

The motor neuron m6A repertoire governs neuronal homeostasis and FTO inhibition mitigates ALS symptom manifestation

Amyotrophic lateral sclerosis (ALS) is a swiftly progressive and fatal neurodegenerative ailment marked by the degenerative motor neurons (MNs). Why MNs are specifically susceptible in predominantly sporadic cases remains enigmatic. Here, we demonstrated N6-methyladenosine (m6A), an RNA modification catalyzed by the METTL3/METTL14 methyltransferase complex, as a pivotal contributor to ALS pathogenesis. By conditional knockout Mettl14 in murine MNs, we recapitulate almost the full spectrum of ALS disease characteristics. Mechanistically, pervasive m6A hypomethylation triggers dysregulated expression of high-risk genes associated with ALS and an unforeseen reduction of chromatin accessibility in MNs. Additionally, we observed diminished m6A levels in induced pluripotent stem cell derived MNs (iPSC~MNs) from familial and sporadic ALS patients. Restoring m6A equilibrium via a small molecule or gene therapy significantly preserves MNs from degeneration and mitigates motor impairments in ALS iPSC~MNs and murine models. Our study presents a substantial stride towards identifying pioneering efficacious ALS therapies via RNA modifications.

RNA modifications and their role in gene expression

Post-transcriptional RNA modifications have recently emerged as critical regulators of gene expression programs. Understanding normal tissue development and disease susceptibility requires knowledge of the various cellular mechanisms which control gene expression in multicellular organisms. Research into how different RNA modifications such as in N6-methyladenosine (m6A), inosine (I), 5-methylcytosine (m5C), pseudouridine (Ψ), 5-hydroxymethylcytosine (hm5C), N1-methyladenosine (m1A), N6,2'-O-dimethyladenosine (m6Am), 2'-O-methylation (Nm), N7-methylguanosine (m7G) etc. affect the expression of genes could be valuable. This review highlights the current understanding of RNA modification, methods used to study RNA modification, types of RNA modification, and molecular mechanisms underlying RNA modification. The role of RNA modification in modulating gene expression in both physiological and diseased states is discussed. The potential applications of RNA modification in therapeutic development are elucidated.

The RMaP challenge of predicting RNA modifications by nanopore sequencing

The field of epitranscriptomics is undergoing a technology-driven revolution. During past decades, RNA modifications like N6-methyladenosine (m6A), pseudouridine (ψ), and 5-methylcytosine (m5C) became acknowledged for playing critical roles in cellular processes. Direct RNA sequencing by Oxford Nanopore Technologies (ONT) enabled the detection of modifications in native RNA, by detecting noncanonical RNA nucleosides properties in raw data. Consequently, the field's cutting edge has a heavy component in computer science, opening new avenues of cooperation across the community, as exchanging data is as impactful as exchanging samples. Therefore, we seize the occasion to bring scientists together within the RNA Modification and Processing (RMaP) challenge to advance solutions for RNA modification detection and discuss ideas, problems and approaches. We show several computational methods to detect the most researched mRNA modifications (m6A, ψ, and m5C). Results demonstrate that a low prediction error and a high prediction accuracy can be achieved on these modifications across different approaches and algorithms. The RMaP challenge marks a substantial step towards improving algorithms' comparability, reliability, and consistency in RNA modification prediction. It points out the deficits in this young field that need to be addressed in further challenges.

Modifications of RNA in cancer: a comprehensive review

RNA modifications play essential roles in post-transcriptional gene regulation and have emerged as significant contributors to cancer biology. Major chemical modifications of RNA include N6-methyladenosine (m6A), 5-methylcytosine (m5C), N1-methyladenosine (m1A), pseudouridine (ψ), and N7-methylguanosine (m7G). Their dynamic regulation highlights their roles in gene expression modulation, RNA stability, and translation. Advanced high-throughput detection methods, ranging from liquid chromatography-mass spectrometry and high-performance liquid chromatography to next-generation sequencing (NGS) and nanopore direct RNA sequencing, have enabled detailed studies of RNA modifications in cancer cells. Aberrant RNA modifications are associated with the dysregulation of tumor suppressor genes and oncogenes, influencing cancer progression, therapy resistance, and immune evasion. Emerging research suggests the therapeutic potential of targeting RNA-modifying enzymes and their inhibitors in cancer treatment. This review compiles and analyzes the latest findings on RNA modifications, presenting an in-depth discussion of the diverse chemical alterations that occur in RNA and their profound implications in cancer biology. It integrates fundamental principles with cutting-edge research, offering a holistic perspective on how RNA modifications influence gene expression, tumor progression, and therapeutic resistance. It emphasizes the need for further studies to elucidate the complex roles of RNA modifications in cancer, as well as the potential for multimodality therapeutic strategies that exploit the dynamic and reversible nature of these epitranscriptomic marks. It also attempts to highlight the challenges, gaps, and limitations of RNA modifications in cancer that should be tackled before their functional implications. Understanding the interplay between RNA modifications, cancer pathways, and their inhibitors will be crucial for developing promising RNA-based therapeutic approaches to cancer and personalized medicine strategies.

Construction of a diagnostic model utilizing m7G regulatory factors for the characterization of diabetic nephropathy and the immune microenvironment

Diabetic nephropathy (DN), a prevalent and severe complication of diabetes, is associated with poor prognosis and limited treatment options. N7-Methylguanosine (m7G) modification plays a crucial role in regulating RNA structure and function, linking it closely to metabolic disorders. However, despite its biological significance, the interplay between m7G methylation and immune status in DN remains largely unexplored. Leveraging data from the GEO database, we conducted consensus clustering of m7G regulators in DN patients to identify distinct molecular subtypes. To construct and validate m7G-related prognostic features and risk scores, we integrated multiple machine learning approaches, including Support Vector Machine-Recursive Feature Elimination, Random Forest, LASSO, Cox regression, and ROC curves analysis. In addition, we employed GSVA, ssGSEA, CIBERSORT, and Gene Set Enrichment Analysis to investigate the associated biological pathways and the immune landscape, providing deeper insights into the role of m7G methylation in DN. Based on the expression levels of 18 m7G-related regulatory factors, we identified nine key regulators. Through machine learning techniques, we identified four significant regulators (METTL1, CYFIP2, EIF3D, and NUDT4). Consensus clustering classified these genes into two distinct m7G-related clusters. To characterize these subtypes, we conducted immune infiltration analysis, differential expression analysis, and enrichment analysis, uncovering significant biological differences between the clusters. Additionally, we developed an m7G-related risk scoring model using the PCA algorithm. The differential expression of the four key regulators was further validated through in vivo experiments, reinforcing their potential role in disease progression. The m7G-related genes METTL1, CYFIP2, EIF3D, and NUDT4 may serve as potential diagnostic biomarkers for DN, providing new insights into its molecular mechanisms and immune landscape.

Integrative approaches to m6A and m5C RNA modifications in autism spectrum disorder revealing potential causal variants

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder that currently affects approximately 1-2% of the global population. Genome-wide studies have identified several loci associated with ASD; however, pinpointing causal variants remains elusive. Therefore, functional studies are essential to discover potential therapeutics for ASD. RNA modification plays a crucial role in the post-transcriptional regulation of mRNA, with m6A and m5C being the most prevalent internal modifications. Recent research indicates their involvement in the regulation of key genes associated with ASD. In this study, we conducted an integrative genomic analysis of ASD, incorporating m6A and m5C variants, followed by cis-eQTL, gene differential expression, and gene enrichment analyses to identify causal variants from a genome-wide study of ASD. We identified 20,708 common m6A-SNPs and 2,407 common m5C-SNPs. Among these, 647 m6A-SNPs exhibited cis-eQTL signals with a p-value < 0.05, while only 81 m5C-SNPs with a p-value < 0.05 showed cis-eQTL signals. Most of these were functional loss variants, with 38 variants representing the most significant common m6A/m5C-SNPs associated with key ASD-related genes. In the gene differential expression analysis, seven proximal genes corresponding to significant m6A/m5C-SNPs were differentially expressed in at least one of the three microarray gene expression profiles of ASD. Key differentially expressed genes corresponding to m6A/m5C cis-variants included KIAA1671 (rs5752063, rs12627825), INTS1 (rs67049052, rs10237910), VSIG10 (rs7965350), TJP2 (rs3812536), FAM167A (rs9693108), TMEM8A (rs1802752), and NUP43 (rs3924871, rs7818, rs9383844, rs9767113). Cell-specific cis-eQTL analysis for proximal gene identification, combined with gene expression datasets from single-cell RNA-seq analysis, would validate the causal relationship of gene regulation in brain-specific regions, and experimental validation in cell lines would achieve the goal of precision medicine.

Transcriptomic Regulation by Astrocytic m6A Methylation in the mPFC

Astrocytes, the most prevalent type of glial cells, have been found to play a crucial part in numerous physiological functions. By offering metabolic and structural support, astrocytes are vital for the proper functioning of the brain and regulating information processing and synaptic transmission. Astrocytes located in the medial prefrontal cortex (mPFC) are highly responsive to environmental changes and have been associated with the development of brain disorders. One of the primary mechanisms through which the brain responds to environmental factors is epitranscriptome modification. M6-methyladenosine methylation is the most prevalent internal modification of eukaryotic messenger RNA (mRNA), and it significantly impacts transcript processing and protein synthesis. However, the effects of m6A on astrocyte transcription and function are still not well understood. Our research demonstrates that ALKBH5, an RNA demethylase of m6A found in astrocytes, affects gene expression in the mPFC. These findings suggest that further investigation into the potential role of astrocyte-mediated m6A methylation in the mPFC is warranted.

The epigenetic approach of varicocele: a focus on sperm DNA and m6A-RNA methylation

BACKGROUND

Varicocele is an abnormal dilation and torsion of the pampiniform venous plexus in the scrotum due to venous reflux, primarily affecting the left side. It affects 15% of men and is a prevalent contributor to male infertility. Varicocele is a complex disorder influenced by genetic, epigenetic, and environmental factors. Epigenetic modifications, which regulate genome activity independently of DNA or RNA sequences, may contribute to the development and severity of varicocele. These include DNA methylation, histone modifications, and RNA modifications like N6-methyladenosine (m6A). Irregularities in DNA and m6A-RNA methylation during spermatogenesis can cause gene expression abnormalities, DNA damage, and decreased fertility in varicocele patients.

OBJECTIVE AND RATIONALE

The review aims to comprehensively understand the underlying mechanisms of varicocele, a condition that can significantly impact male fertility. By exploring the role of methylation modifications, specifically DNA and m6A-RNA methylation, the review aims to synthesize evidence from basic, preclinical, and clinical research to expand the existing knowledge on this subject. The ultimate goal is to identify potential avenues for developing targeted treatments that can effectively improve varicocele and ultimately increase sperm quality in affected individuals.

SEARCH METHODS

A thorough investigation of the scientific literature was conducted through searches in PubMed, Google Scholar, and Science Direct databases until May 2024. All studies investigating the relationship between DNA and m6A-RNA methylation and male infertility, particularly varicocele were reviewed, and the most pertinent reports were included. Keywords such as varicocele, epigenetics, DNA methylation, m6A-RNA methylation, hypermethylation, hypomethylation, spermatozoa, semen parameters, spermatogenesis, and male infertility were used during the literature search, either individually or in combination.

OUTCOMES

The sperm has a specialized morphology essential for successful fertilization, and its epigenome is unique, potentially playing a key role in embryogenesis. Sperm DNA and RNA methylation, major epigenetic marks, regulate the expression of testicular genes crucial for normal spermatogenesis. This review explores the role of DNA and m6A-RNA methylation, in responding to oxidative stress and how various nutrients influence their function in varicocele condition. Evidence suggests a potential link between varicocele and aberrant DNA/m6A-RNA methylation patterns, especially hypomethylation, but the body of evidence is still limited. Further studies are needed to understand how abnormal expression of DNA/m6A-RNA methylation regulators affects testicular gene expression. Thus, analyzing sperm DNA 5mC/5hmC levels and m6A-RNA methylation regulators may reveal spermatogenesis defects and predict reproductive outcomes.

WIDER IMPLICATIONS

Nutri-epigenomics is an emerging field that could enhance the knowledge and management of diseases with unpredictable risks and consequences, even among individuals with similar lifestyles, by elucidating the influence of nutrition on DNA/m6A-RNA methylation through one-carbon metabolism. However, the importance of one-carbon metabolism to varicocele is not well-recognized. Health status and diet influence one-carbon metabolism and its associated DNA/m6A-RNA methylation modification. Future research should identify optimal methylation patterns that promote health and investigate modulating one-carbon metabolism to achieve this. Furthermore, additional studies are necessary to develop personalized dietary strategies through clinical and longitudinal research. However, a research gap exists on dietary interventions utilizing epigenetics as a therapeutic method for treating varicocele.

REGISTRATION NUMBER

Not applicable.

Toward the use of nanopore RNA sequencing technologies in the clinic: challenges and opportunities

RNA molecules have garnered increased attention as potential clinical biomarkers in recent years. While short-read sequencing and quantitative polymerase chain reaction have been the primary methods for quantifying RNA abundance, they typically fail to capture critical post-transcriptional regulatory elements, such as RNA modifications, which are often dysregulated in disease contexts. A promising cutting-edge technique sequencing method that addresses this gap is direct RNA sequencing, offered by Oxford Nanopore Technologies, which can simultaneously capture both RNA abundance and modification information. The rapid advancements in this platform, along with growing evidence of dysregulated RNA species in biofluids, presents a compelling clinical opportunity. In this review, we discuss the challenges and the emerging opportunities for the adoption of nanopore RNA sequencing technologies in the clinic, highlighting their potential to revolutionize personalized medicine and disease monitoring.

TGT Damages its Substrate tRNAs by the Formation of Abasic Sites in the Anticodon Loop

RNA modification is a well-recognized way for gene expression regulation in a living cell. Natural enzymatic RNA modifications have been characterized for decades. Recently, additional mechanisms, more related to RNA damage, have emerged, which do not involve targeted enzymatic activity but nonetheless alter the chemical structure of nucleosides. Aberrantly modified RNA may also appear due to incomplete or erroneous enzymatic reactions. We demonstrate that tRNA-guanine transglycosylase (TGT) in bacteria and eukaryotes accidentally leaves RNA abasic sites (rAP) in the anticodon loop of substrate tRNAs. The formation of an rAP site is a part of the TGT catalytic mechanism, involving the cleavage of the N-glycosidic bond, and the formation of a covalent enzyme-tRNA adduct. The phenomenon of rAP site formation is readily detectable for tRNATyr(GUA) in bacteria and tRNAAsp(GUC) in eukaryotes and is amplified when the supply for preQ1 in bacteria is compromised. The TGT-mediated accumulation of rAP sites in tRNAs is strongly induced upon stress, and most prominent upon oxidative stress in bacteria. Polysome profiling in bacteria points out the partial exclusion of rAP-containing tRNAs from the translating ribosome fraction, prompting a consideration of these tRNA species as "damaged" and most likely non-functional. The exploratory analysis of rAP tRNA(GUN) sites in mice demonstrates a substantial variability among different tissues, with the highest accumulation of damaged tRNA observed in the brain, the lung and the spleen. Altogether, these results uncover a unique molecular mechanism of RNA modification that, via a presumably erroneous reaction, diminishes RNA function rather than enhancing it.

Characterization of transcriptomic changes across Coccidioides morphologies using RiboMarker®-enhanced RNA sequencing

Coccidioides is a dimorphic, pathogenic fungus responsible for transmission of the mammalian disease colloquially known as "Valley fever". To better understand the molecular basis of Coccidioides pathogenesis, previous studies have characterized transcriptomes that define transitions between the saprobic and pathogenic life stages of the two species that cause Valley fever - Coccidioides immitis and Coccidioides posadasii . However, none of these studies have focused on small RNA profiles, which have been shown in several pathogenic fungi to play crucial roles in host-pathogen communication, affecting virulence and infectivity. In this study, we analyzed changes in small RNA expression across three major morphologies of C. posadasii : arthroconidia, mycelia, and spherules, from both intracellular and extracellular fractions. Utilizing RiboMarker® small RNA and RNA fragment library preparation, we show enhanced coverage across the transcriptome by increasing incorporation of normally incompatible RNAs into the sequencing pool. Using these data, we observed transcriptomic shifts during the transition of arthroconidia to either mycelia or spherules, marked largely by changes in both protein-coding, tRNA, and unannotated loci. As little is known regarding the mechanisms governing these life stage transitions, these data provide better insight into those small RNA- and fragment-producing genes and loci that may be required for progression between Coccidioides saprobic and parasitic life cycles. Additionally, analysis of fragmentation patterns across all morphologies suggests unique patterns of RNA fragmentation across a cohort of RNA species that correlate with a given ecotype. Finally, we noted evidence of RNA export to the extracellular space, particularly regarding snRNA and tRNA-derived fragments as well as mRNA-derived transcripts, during the transition to either mycelia or spherules, which may play roles in cell-cell, and/or host-pathogen communication. Going forward, this newly established intra- and extracellular Coccidioides sRNA atlas will provide a foundation for potential biomarker discovery and contribute to our understanding of the molecular basis for virulence in Valley fever.

A microscale thermophoresis-based enzymatic RNA methyltransferase assay enables the discovery of DNMT2 inhibitors

RNA methyltransferases (MTases) have recently become increasingly important in drug discovery. Yet, most frequently utilized RNA MTase assays are limited in their throughput and hamper this rapidly evolving field of medicinal chemistry. This study developed a microscale thermophoresis (MST)-based split aptamer assay for enzymatic MTase investigations, improving current methodologies by offering a non-proprietary, cost-effective, and highly sensitive approach. Our findings demonstrate the assay's effectiveness across different RNA MTases, including inhibitor characterization of METTL3/14, DNMT2, NSUN2, and S. aureus TrmD, enabling future drug discovery efforts. Using this concept, a pilot screening on the cancer drug target DNMT2 discovered several hit compounds with micromolar potency.

Significant roles of RNA 5-methylcytosine methylation in cancer

Cancer stands as a leading cause of mortality and poses an escalating threat to global health. Epigenetic dysregulation is pivotal in the onset and advancement of cancer. Recent research on RNA 5-methylcytosine (m5C) methylation has underscored its significant role in cancer. RNA m5C methylation is a key component in gene expression regulation and is intricately linked to cancer development, offering valuable insights for cancer diagnosis, treatment, and prognosis. This review provides an in-depth examination of the three types of regulators associated with RNA m5C methylation and their biological functions. It further investigates the expression and impact of RNA m5C methylation and its regulators in cancer, focusing on their mechanisms in cancer progression and clinical relevance. The current research on inhibitors targeting RNA m5C methylation-related regulators remains underdeveloped, necessitating further exploration and discovery.

Charting the epitranscriptomic landscape across RNA biotypes using native RNA nanopore sequencing

RNA modifications are conserved chemical features found in all domains of life and across diverse RNA biotypes, shaping gene expression profiles and enabling rapid responses to environmental changes. Their broad chemical diversity and dynamic nature pose significant challenges for studying them comprehensively. These limitations can now be addressed through direct RNA nanopore sequencing (DRS), which allows simultaneous identification of diverse RNA modification types at single-molecule and single-nucleotide resolution. Here, we review recent efforts pioneering the use of DRS to better understand the epitranscriptomic landscape. We highlight how DRS can be applied to investigate different RNA biotypes, emphasizing the use of specialized library preparation protocols and downstream bioinformatic workflows to detect both natural and synthetic RNA modifications. Finally, we provide a perspective on the future role of DRS in epitranscriptomic research, highlighting remaining challenges and emerging opportunities from improved sequencing yields and accuracy enabled by the latest DRS chemistry.

ALKBH5 suppresses gastric cancer tumorigenesis and metastasis by inhibiting the translation of uncapped WRAP53 RNA isoforms in an m6A-dependent manner

The N6-methyladenosine (m6A) modification serves as an essential epigenetic regulator in eukaryotic cells, playing a significant role in tumorigenesis and cancer progression. However, the detailed biological functions and underlying mechanisms of m6A regulation in gastric cancer (GC) are poorly understood. Our research revealed that the m6A demethylase ALKBH5 was markedly downregulated in GC tissues, which was associated with poor patient prognosis. Functional studies demonstrated that suppressing ALKBH5 expression enhanced GC cell proliferation, migration, and invasion. Mechanistically, ALKBH5 removed m6A modifications from the 5' uncapped and polyadenylated transcripts (UPTs) of WRAP53. This demethylation decreased WRAP53 stability and translation efficiency. The lower level of WRAP53 disrupts the interaction between USP6 and RALBP1 protein, promoting RALBP1 degradation and thereby suppressing the PI3K/Akt/mTOR signaling cascade, ultimately attenuating the progression of GC. These findings highlight the pivotal role of ALKBH5-mediated m6A demethylation in inhibiting GC progression and the potential role of ALKBH5 as a promising biomarker and therapeutic target for GC intervention.

m5C methylation modification may be an accomplice in colorectal cancer escaping from anti-tumor effects of innate immunity-type I/III interferon

Colorectal cancer (CRC) is one of the most prevalent malignant tumors in the world, and its occurrence and development are closely related to the complex immune regulatory mechanisms. As the first barrier of the body's defense, innate immunity plays a key role in tumor immune surveillance and anti-tumor response, in which type I/III interferon (IFN) is an important mediator with significant antiviral and anti-tumor functions. 5-methylcytosine (m5C) modification of RNA is a key epigenetic regulation that promotes the expression of CRC oncogenes and immune-related genes. It can enhance the proliferation, migration, and invasion of tumor cells by affecting mRNA stability, translation efficiency, and nuclear export. In addition, m5C modification modulates the activity of innate immune signaling pathways and inhibits interferon production and function, further helping tumor cells evade immune surveillance. However, there are insufficient elucidations on the interaction between m5C modification and innate immunity in CRC. In this study, the mechanism of interferon I/III in colorectal cancer was systematically reviewed and explored. This work focused on how m5C modification promotes tumor immune escape by affecting the interferon signaling pathway, thereby providing new diagnostic markers and therapeutic targets for clinical use, and enhancing the immunotherapy efficacy.

Experimental and computational investigations of RNA duplexes containing N7-regioisomers of adenosine and LNA-adenosine

Although glycosidic bonds in purines typically involve the N9 position, the chemical synthesis of adenosine produces N7-ribofuranosyladenine (7A) as a kinetically favorable ribosylation product. Similarly, in the synthesis of LNA-adenosine (AL), a minor product, N7-LNA-adenosine (7AL), is observed. While extensive research has focused on investigating the properties of N9-regioisomers of adenosine, 7A has been largely overlooked and considered as a side-product. In this study, we conducted comprehensive experimental and computational investigations to elucidate the structural and thermodynamic properties of 7A and 7AL. Our results reveal that 7A and 7AL primarily enhance the thermodynamic stability of 1 × 1 mismatches when paired with purines but decrease stability when paired with pyrimidines. Utilizing nuclear magnetic resonance and computational techniques, we discovered that 1 × 1 7A:A and 7AL:A prefer anti-anti conformations, while 1 × 1 7A:G and 7AL:G prefer syn-anti orientations, both forming two hydrogen bond states, resulting in enhanced duplex stabilities. Altogether, these findings underscore the unique properties of 7A and 7AL when incorporated in RNA, which could advance structure-based RNA studies and potentially be utilized to modulate binding affinity, selectivity and biostability of RNA molecules.

RNA methylation modifications in neurodegenerative diseases: Focus on their enzyme system

BACKGROUND

Neurodegenerative diseases (NDs) constitute a significant public health challenge, as they are increasingly contributing to global mortality and morbidity, particularly among the elderly population. Pathogenesis of NDs is intricate and multifactorial. Recently, post-transcriptional modifications (PTMs) of RNA, with a particular focus on mRNA methylation, have been gaining increasing attention. At present, several regulatory genes associated with mRNA methylation have been identified and closely associated with neurodegenerative disorders.

AIM OF REVIEW

This review aimed to summarize the RNA methylation enzymes system, including the writer, reader, and eraser proteins and delve into their functions in the central nervous system (CNS), hoping to open new avenues for exploring the mechanisms and therapeutic strategies for NDs.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Recently, studies have highlighted the critical role of RNA methylation in the development and function of the CNS, and abnormalities in this process may contribute to brain damage and NDs, aberrant expression of enzymes involved in RNA methylation has been implicated in the onset and development of NDs.

TENT5A Increases Glioma Malignancy and Promotes its Progression

BACKGROUND

Recent studies reported that terminal nucleotidyltransferase 5A (TENT5A) is highly expressed in glioblastoma and associated with poor prognosis. In this work, we aim to specify the expression level of TENT5A in different grades of glioma and explore its role in glioma progression.

METHODS

GEPIA online tools were used to perform the bioinformatic analysis. qRT-PCR, Western blot, and Immunohistochemistry were performed in glioma cells or tissues. Furthermore, CCK8, colony formation, transwell, flow cytometry and scratch assays were performed.

RESULTS

TENT5A was highly expressed in glioma and its level was associated with the pathological grade of glioma. Knockdown of TENT5A suppressed cell proliferation, colony formation ability, cell invasion and migration. Overexpression of TENT5A was lethal to the glioma cells.

CONCLUSION

Our data showed that the expression of TENT5A is associated with the pathological grade of glioma. Knockdown of TENT5A decreased the ability of proliferation, invasion and migration of glioma cells. High levels of TENT5A in glioma cells are lethal. Therefore, TENT5A could be a new target for glioma treatment.

Recent advances in methylation modifications of microRNA

microRNAs (miRNAs) are short single-stranded non-coding RNAs between 21 and 25 nt in length in eukaryotic organisms, which control post-transcriptional gene expression. Through complementary base pairing, miRNAs generally bind to their target messenger RNAs and repress protein production by destabilizing the messenger RNA and translational silencing. They regulate almost all life activities, such as cell proliferation, differentiation, apoptosis, tumorigenesis, and host-pathogen interactions. Methylation modification is the most common RNA modification in eukaryotes. miRNA methylation exists in different types, mainly N6-methyladenosine, 5-methylcytosine, and 7-methylguanine, which can change the expression level and biological mode of action of miRNAs and improve the activity of regulating gene expression in a very fine-tuned way with flexibility. In this review, we will summarize the recent findings concerning methylation modifications of miRNA, focusing on their biogenesis and the potential role of miRNA fate and functions.

Construction and clinical application of a risk model based on N6-methyladenosine regulators for colorectal cancer

Background

Colorectal cancer (CRC) shows a high incidence in developed countries. This study established a prognosis signature based on N6-methyladenosine (m6A) regulators involved in CRC progression.

Method

The bulk RNA-seq data from the Atlas and Compass of Immune-Colon cancer-Microbiome interactions (AC-ICAM) and GSE33113 CRC datasets were obtained from the cBioportal and GEO databases, and a total of 21 m6A regulators genes were collected from a previous study. The scRNA-seq analysis of the GSE146771 cohort was conducted applying the Seurat and harmony R packages. Consensus clustering based on the expressions of m6A regulators was performed with the ConsensusClusterPlus package. The ggGSEA package was used for the Gene Set Enrichment Analysis (GSEA). The un/multivariate and LASSO Cox analysis were performed applying the "survival" and "glmnet" packages for developing a risk model. The pRRophetic and GSVA packages were utilized to analyze potential drugs for CRC and immune infiltration in different risk groups, followed by the Kaplan-Meier (KM) survival and ROC analysis with the "survival" and "timeROC" packages. In vitro assays included the quantitative polymerase chain reaction (qPCR), wound healing and transwell were performed.

Results

CRC patients in the AC-ICAM cohort were assigned into three molecular subtypes (S1, 2 and 3) based on nine m6A regulator genes. Specifically, the prognostic outcome of the S3 was the most favorable, while that of the S1 was the worst and this subtype was associated with the activation of NF-kB, TNF-α and hypoxia pathways. Three key genes, namely, methyltransferase-like 3 (METTL3), insulinolike Growth Factor2 mRNA-Binding Protein 3 (IGF2BP3) and YTH domain-containing protein 2 (YTHDC2), selected from the 9 m6A regulator genes were combined into a RiskScore, which showed a high classification effectiveness in dividing the patients into high- and low-risk groups. Inhibition of the expression of METTL3A or that of IGF2BP3 suppressed the invasion and migration of CRC cells. Notably, the high-risk patients had higher immune cell infiltration to support the activation of multiple immune responses and exhibited significantly poor prognosis. Meanwhile, a nomogram with practical clinical value was developed based on the RiskScore and other clinical features. Finally, eight potential drugs associated with the RiskScore were identified, and CD4+ cells and Tregs were found to be closely associated with CRC progression.

Conclusion

The RiskScore model developed based on m6A regulators played a critical role in CRC development and can be considered as a prognosis predictor for patients with the cancer. The present discoveries will facilitate the diagnosis and clinical management of CRC patients.

Cannabinoids shift the basal ganglia microRNA m 6 A methylation profile towards an anti-inflammatory phenotype in SIV-infected rhesus macaques

Background

Epitranscriptomic modifications modulate diverse biological processes like regulation of gene expression, abundance, location and function. N6-methyladenosine (m 6 A) methylation has been shown to regulate various diseases, including cancer and inflammation. While there is evidence that m 6 A modification is functionally relevant in neural development and differentiation, the role of m 6 A modification in HIV neuropathogenesis is unknown.

Methods

Here, we used anti-N6-methyladenosine (m 6 A) antibody immunoprecipitation and microarray profiling to identify m 6 A modifications in miRNAs in basal ganglia (BG) of Rhesus macaques (RMs) that were uninfected (VEH) and SIV-infected on combination anti-retroviral therapy (cART) and either VEH-treated (VEH/SIV/cART), or THC:CBD-treated (THC:CBD/SIV/cART). Ingenuity pathway analysis was conducted to understand the biological implications of miRNA m 6 A methylation in HIV neuropathogenesis. Finally, to understand the functional significance of m 6 A modifications in miRNAs, we overexpressed FAM-labeled wild-type or m 6 A-modified miR-194-5p in SCC-25 cells and determined its impact on the expression of its target, STAT1, an interferon-stimulated transcription factor known to drive persistent neuroinflammation in several neurodegenerative diseases.

Results

HIV/SIV infection promoted an overall hypomethylated miRNA m 6 A profile. While the overall hypomethylated m 6 A profile was not significantly impacted by THC:CBD, specific miRNAs predicted to target proinflammatory genes showed markedly reduced m 6 A methylation levels compared to the VEH-treated RMs. Additionally, specific BG tissue miRNAs bearing m 6 A epi-transcriptomic marks were transferred and detected in BG-derived extracellular vesicles. Mechanistically, the DRACH motif in the seed region of miR-194-5p was significantly m 6 A hypomethylated in THC:CBD/SIV/cART RMs. In SCC-25 cells, unlike wild-type miR-194-5p, transfected m 6 A-modified miR-194-5p mimics failed to downregulate STAT1 protein expression. Further, compared to VEH/SIV/cART RMs, THC:CBD administration significantly reduced m 6 A methylation of 44 miRNAs directly involved in regulating CNS network genes.

Conclusions

These results underscore the need for investigating the qualitative, and posttranscriptional modifications in RNA along with the more traditional, quantitative alterations in pathological conditions or in response to disease modifying treatments. Our findings indicate that m 6 A epitranscriptomic marks in the seed nucleotide region can impair miRNA function and that cannabinoids may preserve it by reducing m 6 A methylation levels. Finally, these findings provide a novel mechanistic (miRNA m 6 A hypomethylation) explanation underlying the anti-neuroinflammatory effects of phytocannabinoids in HIV/SIV infection.

Native RNA nanopore sequencing reveals antibiotic-induced loss of rRNA modifications in the A- and P-sites

The biological relevance and dynamics of mRNA modifications have been extensively studied; however, whether rRNA modifications are dynamically regulated, and under which conditions, remains unclear. Here, we systematically characterize bacterial rRNA modifications upon exposure to diverse antibiotics using native RNA nanopore sequencing. To identify significant rRNA modification changes, we develop NanoConsensus, a novel pipeline that is robust across RNA modification types, stoichiometries and coverage, with very low false positive rates, outperforming all individual algorithms tested. We then apply NanoConsensus to characterize the rRNA modification landscape upon antibiotic exposure, finding that rRNA modification profiles are altered in the vicinity of A and P-sites of the ribosome, in an antibiotic-specific manner, possibly contributing to antibiotic resistance. Our work demonstrates that rRNA modification profiles can be rapidly altered in response to environmental exposures, and provides a robust workflow to study rRNA modification dynamics in any species, in a scalable and reproducible manner.

Nanomole Scale Screening of Fluorescent RNA-Methyltransferase Probes Enables the Discovery of METTL1 Inhibitors

RNA methylation is a metabolic process validated for its association with various diseases, and thus, RNA methyltransferases (MTases) have become increasingly important in drug discovery. Yet, most frequently utilized RNA MTase assays are limited in their throughput and hamper this rapidly evolving field of medicinal chemistry. In this study, we describe a modular nanomole scale building block system that allowed the identification of tailored fluorescent MTase probes to unlock a broad selection of MTase drug targets for fluorescence-based binding assays. Probe candidates were initially prepared on a 4 nanomole scale and could be tested directly from crude reaction mixtures to allow rapid probe identification and optimization. Using an alkyne-azide click late-stage functionalization strategy and in silico protein databank mining, we established a selection of fluorescent probes suitable for relevant drug targets from the METTL and NSUN families, as well as bacterial and viral MTases. Using this concept, a high-throughput screening on the unexplored drug target METTL1 discovered three hit compounds with micromolar potency providing a (1H-pyrazol-4-yl)pyridine-based starting point for METTL1 drug discovery.

Deep-m5U: a deep learning-based approach for RNA 5-methyluridine modification prediction using optimized feature integration

BACKGROUND

RNA 5-methyluridine (m5U) modifications play a crucial role in biological processes, making their accurate identification a key focus in computational biology. This paper introduces Deep-m5U, a robust predictor designed to enhance the prediction of m5U modifications. The proposed method, named Deep-m5U, utilizes a hybrid pseudo-K-tuple nucleotide composition (PseKNC) for sequence formulation, a Shapley Additive exPlanations (SHAP) algorithm for discriminant feature selection, and a deep neural network (DNN) as the classifier.

RESULTS

The model was evaluated using two benchmark datasets, i.e., Full Transcript and Mature mRNA. Deep-m5U achieved overall accuracies of 91.47% and 95.86% for the Full Transcript and Mature mRNA datasets with 10-fold cross-validation, and for independent samples, the model attained 92.94% and 95.17% accuracy.

CONCLUSION

Compared to existing models, Deep-m5U showed approximately 5.23% and 3.73% higher accuracy on the training data and 3.95% and 3.26% higher accuracy on independent samples for the Full Transcript and Mature mRNA datasets, respectively. The reliability and effectiveness of Deep-m5U make it a valuable tool for scientists and a potential asset in pharmaceutical design and research.

Comprehensive analysis of the relationship between RNA modification writers and immune microenvironment in head and neck squamous cell carcinoma

OBJECTIVES

Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Four types of RNA modification writers (m6A, m1A, A-I editing, and APA) are widely involved in tumorigenesis and the TME. We aimed to comprehensively explore the role of the four RNA modification writers in the progression and immune microenvironment of HNSCC.

MATERIALS AND METHODS

We first obtained transcription profile data and transcriptional variation of the four types of RNA modification writers from The Cancer Genome Atlas (TCGA) database. HNSCC patients in TCGA dataset were divided into different clusters based on the four types of RNA modification writers. Univariate Cox and Least absolute shrinkage and selection operator (LASSO) analyses were performed to conduct a Writer-score scoring system, which was successfully verified in the GSE65858 dataset and our clinical sample dataset. Finally, we evaluated the relationship between different RNA modification clusters (Writer-score) and immunological characteristics of HNSCC.

RESULTS

Two different RNA modification clusters (A and B) were obtained. These RNA modification clusters (Writer-score) were strongly associated with immunological characteristics (immunomodulators, cancer immunity cycles, infiltrating immune cells (TIICs), inhibitory immune checkpoints, and T cell inflamed score (TIS)) of HNSCC.

CONCLUSIONS

This study identified two different RNA modification clusters and explored the potential relationship between RNA modification clusters (Writer-score) and immunological characteristics, offering a new theoretical basis for precision immunotherapy in patients with HNSCC.

The interplay between epitranscriptomic RNA modifications and neurodegenerative disorders: Mechanistic insights and potential therapeutic strategies

Neurodegenerative disorders encompass a group of age-related conditions characterized by the gradual decline in both the structure and functionality of the central nervous system (CNS). RNA modifications, arising from the epitranscriptome or RNA-modifying protein mutations, have recently been observed to contribute significantly to neurodegenerative disorders. Specific modifications like N6-methyladenine (m6A), N1-methyladenine (m1A), 5-methylcytosine (m5C), pseudouridine and adenosine-to-inosine (A-to-I) play key roles, with their regulators serving as crucial therapeutic targets. These epitranscriptomic changes intricately control gene expression, influencing cellular functions and contributing to disease pathology. Dysregulation of RNA metabolism, affecting mRNA processing and noncoding RNA biogenesis, is a central factor in these diseases. This review underscores the complex relationship between RNA modifications and neurodegenerative disorders, emphasizing the influence of RNA modification and the epitranscriptome, exploring the function of RNA modification enzymes in neurodegenerative processes, investigating the functional consequences of RNA modifications within neurodegenerative pathways, and evaluating the potential therapeutic advancements derived from assessing the epitranscriptome.

m6A-related genes and their role in Parkinson's disease: Insights from machine learning and consensus clustering

Parkinson disease (PD) is a chronic neurological disorder primarily characterized by a deficiency of dopamine in the brain. In recent years, numerous studies have highlighted the substantial influence of RNA N6-methyladenosine (m6A) regulators on various biological processes. Nevertheless, the specific contribution of m6A-related genes to the development and progression of PD remains uncertain. In this study, we performed a differential analysis of the GSE8397 dataset in the Gene Expression Omnibus database and selected important m6A-related genes. Candidate m6A-related genes were then screened using a random forest model to predict the risk of PD. A nomogram model was built based on the candidate m6A-related genes. By employing a consensus clustering method, PD was divided into different m6A clusters based on the selected significant m6A-related genes. Finally, we performed immune cell infiltration analysis to explore the immune infiltration between different clusters. We performed a differential analysis of the GSE8397 dataset in the Gene Expression Omnibus database and selected 11 important m6A-related genes. Four candidate m6A-related genes (YTH Domain Containing 2, heterogeneous nuclear ribonucleoprotein C, leucine-rich pentatricopeptide repeat motif containing protein and insulin-like growth factor binding protein-3) were then screened using a random forest model to predict the risk of PD. A nomogram model was built based on the 4 candidate m6A-related genes. The decision curve analysis indicated that patients can benefit from the nomogram model. By employing a consensus clustering method, PD was divided into 2 m6A clusters (cluster A and cluster B) based on the selected significant m6A-related genes. The immune cell infiltration analysis revealed that cluster A and cluster B exhibit distinct immune phenotypes. In conclusion, m6A-related genes play a significant role in the development of PD and our study on m6A clustering may potentially guide personalized treatment strategies for PD in the future.

N6-methyladenosine and its epitranscriptomic effects on hematopoietic stem cell regulation and leukemogenesis

N6-methyladenosine (m6A) RNA modification orchestrates cellular epitranscriptome through tuning the homeostasis of transcript stability, translation efficiency, and the transcript affinity toward RNA-binding proteins (RBPs). An aberrant m6A deposition on RNA can lead toward oncogenic expression profile (mRNA), impaired mitochondrial metabolism (mtRNA), and translational suppression (rRNA) of tumor suppressor genes. In addition, non-coding RNAs (ncRNAs), such as X-inactive specific transcript (XIST), miRNAs, and α-ketoglutarate-centric metabolic transcripts are also regulated by the m6A epitranscriptome. Notably, recent studies had uncovered a myriad of m6A-modified transcripts the center of hematopoietic stem cell (HSC) regulation, in which m6A modification act as a context dependent switch to the on and off of hematopoietic stem cell (HSC) maintenance, lineage commitment and terminal differentiation. In this review, we sequentially unfold the m6A mediated epithelial-to-hematopoietic transition in progenitor blood cell production, lymphocytic lineage expansion (T cells, B cells, NK cells, and non-NK ILCs), and the m6A crosstalk with the onco-metabolic prospects of leukemogenesis. Together, an encompassing body of evidence highlighted the emerging m6A significance in the regulation of HSC biology and leukemogenesis.

Integrated Biochemical and Computational Methods for Deciphering RNA-Processing Codes

RNA processing involves steps such as capping, splicing, polyadenylation, modification, and nuclear export. These steps are essential for transforming genetic information in DNA into proteins and contribute to RNA diversity and complexity. Many biochemical methods have been developed to profile and quantify RNAs, as well as to identify the interactions between RNAs and RNA-binding proteins (RBPs), especially when coupled with high-throughput sequencing technologies. With the rapid accumulation of diverse data, it is crucial to develop computational methods to convert the big data into biological knowledge. In particular, machine learning and deep learning models are commonly utilized to learn the rules or codes governing the transformation from DNA sequences to intriguing RNAs based on manually designed or automatically extracted features. When precise enough, the RNA codes can be incredibly useful for predicting RNA products, decoding the molecular mechanisms, forecasting the impact of disease variants on RNA processing events, and identifying driver mutations. In this review, we systematically summarize the biochemical and computational methods for deciphering five important RNA codes related to alternative splicing, alternative polyadenylation, RNA localization, RNA modifications, and RBP binding. For each code, we review the main types of experimental methods used to generate training data, as well as the key features, strategic model structures, and advantages of representative tools. We also discuss the challenges encountered in developing predictive models using large language models and extensive domain knowledge. Additionally, we highlight useful resources and propose ways to improve computational tools for studying RNA codes.

A-to-I RNA editing and hematopoiesis

Adenosine-to-inosine (A-to-I) RNA editing plays essential roles in modulating normal development and homeostasis. This process is catalyzed by adenosine deaminase acting on RNA (ADAR) family proteins. The most well-understood biological processes modulated by A-to-I editing are innate immunity and neurological development, attributed to ADAR1 and ADAR2, respectively. A-to-I editing by ADAR1 is also critical in regulating hematopoiesis. This review will focus on the role of A-to-I RNA editing and ADAR enzymes, particularly ADAR1, during normal hematopoiesis in humans and mice. Furthermore, we will discuss Adar1 mouse models that have been developed to understand the contribution of ADAR1 to hematopoiesis and its role in innate immune pathways.

m6A-Dependent ITIH1 Regulated by TGF-β Acts as a Target for Hepatocellular Carcinoma Progression

Both the transforming growth factor beta (TGF-β) signaling pathway and N6-methyladenosine (m6A) modification for mRNA play an important role in hepatocellular carcinoma (HCC) progression. However, the relationship between TGF-β and m6A in hepatocellular carcinoma (HCC) remains unclear. Here, it is found that TGF-β can promote the liquid phase separation of METTL3, which further leads to the reduction of mRNA stability of ITIH1. As a secreted protein, ITIH1 can act as a ligand of integrin α5β1 to antagonize fibronectin, induce the inhibition of focal adhesion kinase signaling pathway, and inhibit the progression of HCC. In the preclinical model (mouse model, patient-derived organoid, patient-derived xenografts), purified recombinant ITIH1 (r-ITIH1) protein can be targeted for HCC. More importantly, r-ITIH1 can play a synergistic role in targeting HCC with TGF-β inhibitor. The downstream ITIH1 regulatory mechanism of TGF-β and m6A modification is revealed, and ITIH1 can be translational as a potential target for HCC.

Multiomics Studies on Metabolism Changes in Alcohol-Associated Liver Disease

Metabolic dysfunction in the liver represents a predominant feature in the early stages of alcohol-associated liver disease (ALD). However, the mechanisms underlying this are only partially understood. To investigate the metabolic characteristics of the liver in ALD, we did a relative quantification of polar metabolites and lipids in the liver of mice with experimental ALD using untargeted metabolomics and untargeted lipidomics. A total of 99 polar metabolites had significant abundance alterations in the livers of alcohol-fed mice. Pathway analysis revealed that amino acid metabolism was the most affected by alcohol in the mouse liver. Metabolites involved in glycolysis and the TCA cycle were decreased, while glycerol 3-phosphate (G3P) and long-chain fatty acids were increased. Relative quantification of lipids unveiled an upregulation of multiple lipid classes, suggesting that alcohol consumption drives metabolism toward lipid synthesis. Results from enzyme expression and activity detection indicated that the decreased activity of mitochondrial glycerol 3-phosphate dehydrogenase contributed to the disordered metabolism.

Smooth muscle expression of RNA editing enzyme ADAR1 controls activation of RNA sensor MDA5 in atherosclerosis

Mapping the genomic architecture of complex disease has been predicated on the understanding that genetic variants influence disease risk through modifying gene expression. However, recent discoveries have revealed that a significant burden of disease heritability in common autoinflammatory disorders and coronary artery disease is mediated through genetic variation modifying post-transcriptional modification of RNA through adenosine-to-inosine (A-to-I) RNA editing. This common RNA modification is catalyzed by ADAR enzymes, where ADAR1 edits specific immunogenic double stranded RNA (dsRNA) to prevent activation of the double strand RNA (dsRNA) sensor MDA5 ( IFIH1 ) and stimulation of an interferon stimulated gene (ISG) response. Multiple lines of human genetic data indicate impaired RNA editing and increased dsRNA sensing by MDA5 to be an important mechanism of coronary artery disease (CAD) risk. Here, we provide a crucial link between observations in human genetics and mechanistic cell biology leading to progression of CAD. Through analysis of human atherosclerotic plaque, we implicate the vascular smooth muscle cell (SMC) to have a unique requirement for RNA editing, and that ISG induction occurs in SMC phenotypic modulation, implicating MDA5 activation. Through culture of human coronary artery SMCs, generation of a conditional SMC specific Adar1 deletion mouse model on a pro-atherosclerosis background with additional constitutive deletion of MDA5 ( Ifih1 ), and with incorporation of single cell RNA sequencing cellular profiling, we further show that Adar1 controls SMC phenotypic state by regulating Mda5 activation, is required to maintain vascular integrity, and controls progression of atherosclerosis and vascular calcification. Through this work, we describe a fundamental mechanism of CAD, where cell type and context specific RNA editing and sensing of dsRNA mediates disease progression, bridging our understanding of human genetics and disease causality.

One Sentence Summary

Smooth muscle expression of RNA editing enzyme ADAR1 regulates activation of double strand RNA sensor MDA5 in novel mechanism of atherosclerosis.

Epitranscriptomics and cervical cancer: the emerging role of m6A, m5C and m1A RNA modifications

Cervical cancer (CC), one of the most prevalent and detrimental gynaecologic cancers, evolves through genetic and epigenetic alterations resulting in the promotion of oncogenic activity and dysfunction of tumour-suppressing mechanisms. Despite medical advancement, the prognosis for advanced-stage patients remains extremely low due to high recurrence rates and resistance to existing treatments. Thereby, the search for potential prognostic biomarkers is heightened to unravel new modalities of CC pathogenesis and to develop novel anti-cancer therapies. Epitranscriptomic modifications, reversible epigenetic RNA modifications, regulate various biological processes by deciding RNA fate to mediating RNA interactions. This narrative review provides insight into the cellular and molecular roles of endogenous RNA-editing proteins and their associated epitranscriptomic modifications, especially N6-methyladenosine (m6A), 5-methylcytosine (m5C) and N1-methyladenosine (m1A), in governing the development, progression and metastasis of CC. We discussed the in-depth epitranscriptomic mechanisms underlying the regulation of over 50 RNAs responsible for tumorigenesis, proliferation, migration, invasion, survival, autophagy, stemness, epithelial-mesenchymal transition, metabolism (glucose, lipid, glutamate and glutamine), resistance (drug and radiation), angiogenesis and recurrence of CC. Additionally, we provided a concise overview of the therapeutic potential of targeting the altered expression of endogenous RNA-editing proteins and aberrant deposition of RNA modifications on both coding and non-coding RNAs in CC.

Next-Generation Sequencing and Emerging Technologies

Genetic sequencing technologies are evolving at a rapid pace with major implications for research and clinical practice. In this review, the authors provide an updated overview of next-generation sequencing (NGS) and emerging methodologies. NGS has tremendously improved sequencing output while being more time and cost-efficient in comparison to Sanger sequencing. The authors describe short-read sequencing approaches, such as sequencing by synthesis, ion semiconductor sequencing, and nanoball sequencing. Third-generation long-read sequencing now promises to overcome many of the limitations of short-read sequencing, such as the ability to reliably resolve repeat sequences and large genomic rearrangements. By combining complementary methods with massively parallel DNA sequencing, a greater insight into the biological context of disease mechanisms is now possible. Emerging methodologies, such as advances in nanopore technology, in situ nucleic acid sequencing, and microscopy-based sequencing, will continue the rapid evolution of this area. These new technologies hold many potential applications for hematological disorders, with the promise of precision and personalized medical care in the future.

Review of METTL3 in colorectal cancer: From mechanisms to the therapeutic potential

N6-methyladenosine (m6A), the most abundant modification in mRNAs, affects the fate of the modified RNAs at the post-transcriptional level and participants in various biological and pathological processes. Increasing evidence shows that m6A modification plays a role in the progression of many malignancies, including colorectal cancer (CRC). As the only catalytic subunit in methyltransferase complex, methyltransferase-like 3 (METTL3) is essential to the performance of m6A modification. It has been found that METTL3 is associated with the prognosis of CRC and significantly influences various aspects of CRC, such as cell proliferation, invasion, migration, metastasis, metabolism, tumor microcirculation, tumor microenvironment, and drug resistance. The relationship between METTL3 and gut-microbiota is also involved into the progression of CRC. Furthermore, METTL3 might be a viable target for CRC treatment to prolong survival. In this review, we comprehensively summarize the function of METTL3 in CRC and the underlying molecular mechanisms. We aim to deepen understanding and offer new ideas for diagnostic biomarkers and therapeutic targets for colorectal cancer.

tRNA expression and modification landscapes, and their dynamics during zebrafish embryo development

tRNA genes exist in multiple copies in the genome of all organisms across the three domains of life. Besides the sequence differences across tRNA copies, extensive post-transcriptional modification adds a further layer to tRNA diversification. Whilst the crucial role of tRNAs as adapter molecules in protein translation is well established, whether all tRNAs are actually expressed, and whether the differences across isodecoders play any regulatory role is only recently being uncovered. Here we built upon recent developments in the use of NGS-based methods for RNA modification detection and developed tRAM-seq, an experimental protocol and in silico analysis pipeline to investigate tRNA expression and modification. Using tRAM-seq, we analysed the full ensemble of nucleo-cytoplasmic and mitochondrial tRNAs during embryonic development of the model vertebrate zebrafish. We show that the repertoire of tRNAs changes during development, with an apparent major switch in tRNA isodecoder expression and modification profile taking place around the start of gastrulation. Taken together, our findings suggest the existence of a general reprogramming of the expressed tRNA pool, possibly gearing the translational machinery for distinct stages of the delicate and crucial process of embryo development.

Mass Spectrometry Analysis of Nucleic Acid Modifications: From Beginning to Future

Nucleic acids are fundamental biological molecules that encode and convey genetic information within living organisms. Over 150 modifications have been found in nucleic acids, which are involved in critical biological functions, including regulating gene expression, stabilizing nucleic acid structure, modulating protein translation, and so on. The dysregulation of nucleic acid modifications is correlated with many diseases such as cancers and neurological disorders. However, it is still challenging to simultaneously characterize and quantify diverse modifications using traditional genomic methods. Mass spectrometry (MS) has served as a crucial tool to solve this issue, and can directly identify the modified species through their distinct mass differences compared to the canonical ones and provide accurate quantitative information. This review surveys the history of nucleic acid modification discovery, advancements in MS-based methods, nucleic acid sample preparation, and applications in biological and medical research. We expect the high-throughput and valuable quantitative information from MS analysis will be more broadly applied to studying nucleic acid modification status in different pathological conditions, which is key to filling gaps in traditional genomics and transcriptomics research and enabling researchers to gain insights into epigenetics and epitranscriptomics.

Chemistry of installing epitranscriptomic 5-modified cytidines in RNA oligomers

Studies of 5-hydroxymethylcytidine (hm5C), 5-formylcytidine (f5C) and 5-carboxycytidine (ca5C) modifications as products of the 5-methylcytidine (m5C) oxidative demethylation pathway in cellular mRNAs constitute an important element of the new epitranscriptomic field of research. The dynamic process of m5C conversion and final turnover to the parent cytidine is considered a post-transcriptional layer of gene-expression regulation. However, the regulatory mechanism associated with epitranscriptomic cytidine modifications remains largely unknown. Therefore, oligonucleotides containing m5C oxidation products are of great value for the next generation of biochemical, biophysical, and structural studies on their function, metabolism, and contribution to human diseases. Herein, we summarize the synthetic strategies developed for the incorporation of hm5C, f5C and ca5C into RNA oligomers by phosphoramidite chemistry, including post-synthetic C5-cytidine functionalization and enzymatic methods.

N1-Methylpseudouridine and pseudouridine modifications modulate mRNA decoding during translation

The ribosome utilizes hydrogen bonding between mRNA codons and aminoacyl-tRNAs to ensure rapid and accurate protein production. Chemical modification of mRNA nucleobases can adjust the strength and pattern of this hydrogen bonding to alter protein synthesis. We investigate how the N1-methylpseudouridine (m1Ψ) modification, commonly incorporated into therapeutic and vaccine mRNA sequences, influences the speed and fidelity of translation. We find that m1Ψ does not substantially change the rate constants for amino acid addition by cognate tRNAs or termination by release factors. However, we also find that m1Ψ can subtly modulate the fidelity of amino acid incorporation in a codon-position and tRNA dependent manner in vitro and in human cells. Our computational modeling shows that altered energetics of mRNA:tRNA interactions largely account for the context dependence of the low levels of miscoding we observe on Ψ and m1Ψ containing codons. The outcome of translation on modified mRNA bases is thus governed by the sequence context in which they occur.

Structural perspectives on adenosine to inosine RNA editing by ADARs

Adenosine deaminases acting on RNA (ADARs) are enzymes that catalyze the hydrolytic deamination of adenosine to inosine. The editing feature of ADARs has garnered much attention as a therapeutic tool to repurpose ADARs to correct disease-causing mutations at the mRNA level in a technique called site-directed RNA editing (SDRE). Administering a short guide RNA oligonucleotide that hybridizes to a mutant sequence forms the requisite dsRNA substrate, directing ADARs to edit the desired adenosine. However, much is still unknown about ADARs' selectivity and sequence-specific effects on editing. Atomic-resolution structures can help provide additional insight to ADARs' selectivity and lead to novel guide RNA designs. Indeed, recent structures of ADAR domains have expanded our understanding on RNA binding and the base-flipping catalytic mechanism. These efforts have enabled the rational design of improved ADAR guide strands and advanced the therapeutic potential of the SDRE approach. While no full-length structure of any ADAR is known, this review presents an exposition of the structural basis for function of the different ADAR domains, focusing on human ADAR2. Key insights are extrapolated to human ADAR1, which is of substantial interest because of its widespread expression in most human tissues.