GO:0009451 RNA modification: Genes, Functions & Methods

RNA modification (GO:0009451) encompasses the covalent chemical alteration of nucleotides within an RNA molecule, producing an RNA sequence that differs from the genetically encoded sequence. This biological process, often referred to as the epitranscriptome, includes diverse modifications such as N6-methyladenosine (m6A), pseudouridine (Ψ), 5-methylcytosine (m5C), N1-methyladenosine (m1A), 2'-O-methylation, and many others. These modifications are installed, removed, and interpreted by specialized protein machineries that dynamically regulate RNA fate, including stability, splicing, export, translation, and decay. Since the discovery that RNA modifications are reversible and dynamically regulated, the field has expanded rapidly, revealing critical roles in development, immunity, and disease. For example, m6A modification controls T cell differentiation and immune homeostasis, while aberrant expression of RNA modification enzymes drives oncogenesis in multiple cancer types. In cardiovascular disease, RNA modifications influence cardiomyocyte survival, fibrosis, and inflammation. Furthermore, the incorporation of modified nucleosides such as pseudouridine into mRNA vaccines has revolutionized vaccine efficacy and stability. For researchers, understanding RNA modification is essential because it provides a mechanistic layer of gene regulation that operates post-transcriptionally. Targeting RNA modification enzymes with small molecules or CRISPR-based genetic tools holds promise for treating cancer, immune disorders, and cardiovascular diseases. This article summarizes the current knowledge of RNA modification, its key genes, regulatory mechanisms, disease relevance, and experimental approaches for studying this process.

According to the Gene Ontology (GO:0009451), RNA modification is the covalent alteration of one or more nucleotides within an RNA molecule to produce an RNA molecule with a sequence that differs from that coded genetically. This definition encompasses both enzymatic and non-enzymatic chemical changes to RNA bases or the ribose backbone, including methylation, pseudouridylation, acetylation, and other modifications. The term is synonymous with RNA editing in a broad sense, although classical RNA editing often refers specifically to nucleotide insertion, deletion, or substitution.

RNA modification is critically important because it represents a dynamic and reversible layer of post-transcriptional gene regulation that influences nearly every aspect of RNA metabolism, from splicing and nuclear export to translation and decay. Dysregulation of RNA modification machinery is increasingly recognized as a driver of human diseases, including multiple cancers, cardiovascular disorders, and immune dysfunctions. Moreover, the therapeutic potential of targeting RNA modification enzymes is underscored by the success of mRNA vaccines that rely on modified nucleosides, such as pseudouridine, to enhance stability and reduce immunogenicity. Understanding RNA modification thus offers new opportunities for biomarker discovery and therapeutic intervention.

The following table lists key genes and proteins involved in RNA modification, including writers, erasers, and readers, along with their major roles and research relevance.

RNA modification is regulated at multiple levels. Writer and eraser enzymes are subject to transcriptional and post-translational regulation, including phosphorylation, ubiquitination, and SUMOylation, which affect their stability, localization, and activity. For example, METTL3 phosphorylation by AKT modulates its methyltransferase activity and oncogenic function. The availability of cofactors such as S-adenosylmethionine (SAM) also influences m6A deposition, linking RNA modification to cellular metabolism. Additionally, microRNAs and long non-coding RNAs can target writer or eraser mRNAs, creating feedback loops. In immune cells, signaling pathways such as NF-κB and mTOR regulate the expression of RNA modification enzymes, thereby shaping immune responses. The dynamic interplay between writers, erasers, and readers ensures that RNA modification is responsive to developmental and environmental cues.

Dysregulation of RNA modification machinery is a hallmark of many cancers. METTL3 is overexpressed in acute myeloid leukemia (AML) and promotes leukemogenesis by enhancing translation of oncoproteins such as MYC and BCL2. FTO is upregulated in AML and functions as an oncogene by demethylating critical mRNAs. In glioblastoma, ALKBH5-mediated demethylation of FOXM1 mRNA promotes tumorigenicity. YTHDF1 and IGF2BP1 are often overexpressed in solid tumors and correlate with poor prognosis. In gynecological cancers, including ovarian and cervical cancer, RNA modification regulators serve as promising biomarkers and therapeutic targets. Small-molecule inhibitors targeting METTL3, FTO, and ALKBH5 are under development.

RNA modifications contribute to the pathogenesis of cardiovascular diseases, including cardiac hypertrophy, fibrosis, and heart failure. m6A modification regulates cardiomyocyte survival and apoptosis; for instance, METTL3-mediated m6A on specific mRNAs can promote or suppress cardiac hypertrophy depending on context. FTO has been linked to obesity-related cardiac dysfunction. In vascular smooth muscle cells, m6A modification influences proliferation and migration, contributing to atherosclerosis. Targeting RNA modification enzymes may offer new therapeutic avenues for cardiovascular disease.

RNA modification is essential for immune cell development and function. m6A modification controls T cell differentiation, activation, and exhaustion. METTL3 deficiency in T cells leads to impaired immune responses and autoimmunity in mouse models. In mRNA vaccines, incorporation of pseudouridine and other modified nucleosides enhances stability and reduces innate immune activation, leading to improved vaccine efficacy. The success of COVID-19 mRNA vaccines has highlighted the importance of RNA modification in vaccine design. Dysregulated RNA modification is also implicated in autoimmune diseases such as systemic lupus erythematosus.

RNA modification enzymes are critical for brain development and function. Mutations in DKC1 cause dyskeratosis congenita, a ribosomopathy characterized by bone marrow failure and neurological abnormalities. FTO variants are associated with obesity and altered brain function. In neurons, m6A modification regulates synaptic plasticity and memory formation. Emerging evidence links RNA modification dysregulation to neurodegenerative diseases such as Alzheimer's and Parkinson's, although the mechanisms remain under investigation.

High-throughput sequencing methods are essential for mapping RNA modifications transcriptome-wide. m6A-seq (MeRIP-seq) uses m6A-specific antibodies to immunoprecipitate modified RNA fragments, followed by next-generation sequencing to identify m6A sites. miCLIP and m6A-CLIP provide single-nucleotide resolution. Pseudouridine mapping is achieved through Ψ-seq, Pseudo-seq, and RBS-seq, which exploit the unique chemical reactivity of pseudouridine. m5C can be mapped using bisulfite sequencing (RNA-BS-seq) or 5-azacytidine-mediated approaches. These methods have revealed that RNA modifications are dynamically regulated and enriched in specific sequence contexts.

CRISPR-Cas9 knockout, point mutation, and knock-in models are powerful tools for dissecting the causal roles of RNA modification enzymes. Knockout of METTL3 in cell lines abolishes m6A deposition and leads to altered gene expression and cell death. Point mutations that inactivate catalytic activity but preserve protein interactions help distinguish enzymatic from non-enzymatic functions. Knock-in of tagged versions of writers or readers enables localization and interaction studies. RNA interference (RNAi) provides a complementary approach for transient knockdown, especially in primary cells. These genetic tools are essential for validating targets identified by sequencing.

Proteomic approaches identify the protein complexes and interaction networks involved in RNA modification. Affinity purification coupled with mass spectrometry (AP-MS) has been used to define the m6A writer complex, including METTL3, METTL14, WTAP, VIRMA, and ZC3H13. Proximity labeling methods such as BioID and APEX can map the interactome of RNA modification enzymes in living cells. These techniques reveal dynamic interactions that regulate modification deposition and reading.

Imaging techniques allow visualization of RNA modifications at the cellular level. Fluorescent RNA aptamers and modified nucleotide-specific antibodies can detect m6A in fixed cells. Single-molecule imaging has been used to track the dynamics of m6A reader binding to mRNA in real time. Single-cell RNA sequencing (scRNA-seq) combined with modification mapping (e.g., scm6A-seq) reveals heterogeneity in RNA modification across cell populations. These approaches are particularly valuable for studying rare cell types and developmental transitions.

Researchers studying RNA modification-related genes often need to determine whether a candidate gene is causally involved in a specific biological process or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to enable precise genetic manipulation of RNA modification writers, erasers, and readers, accelerating functional validation and therapeutic development.

RNA modification (GO:0009451) is a fundamental biological process that dynamically regulates RNA fate and gene expression. With over 170 known modifications and a complex machinery of writers, erasers, and readers, this epitranscriptomic layer is essential for development, immunity, and disease. Dysregulation of RNA modification is causally linked to cancer, cardiovascular disease, and immune disorders, making these enzymes attractive therapeutic targets. The success of pseudouridine-modified mRNA vaccines further highlights the translational potential of this field. Continued research using CRISPR-based models and advanced sequencing technologies will undoubtedly uncover new insights and therapeutic opportunities.