Methylation 5mC Research Articles

Integrative 5-Methylcytosine Modification Immunologically Reprograms Tumor Microenvironment Characterizations and Phenotypes of Clear Cell Renal Cell Carcinoma.

The tumor microenvironment (TME) affects the biologic malignancy of clear cell renal cell carcinoma (ccRCC). The influence of the 5-methylcytosine (m5C) epigenetic modification on the TME is unknown. We comprehensively assessed m5C modification patterns of 860 ccRCC samples (training, testing, and real-world validation cohorts) based on 17 m5C regulators and systematically integrated the modification patterns with TME cell-infiltrating characterizations. Our results identified distinct m5C modification clusters with gradual levels of immune cell infiltration. The distinct m5C modification patterns differ in clinicopathological features, genetic heterogeneity, patient prognosis, and treatment responses of ccRCC. An elevated m5C score, characterized by malignant biologic processes of tumor cells and suppression of immunity response, implies an immune-desert TME phenotype and is associated with dismal prognosis of ccRCC. Activation of exhausted T cells and effective immune infiltration were observed in the low m5C score cluster, reflecting a noninflamed and immune-excluded TME phenotype with favorable survival and better responses to immunotherapy. Together, these findings provide insights into the regulation mechanisms of DNA m5C methylation modification patterns on the tumor immune microenvironment. Comprehensive assessment of tumor m5C modification patterns may enhance our understanding of TME cell-infiltrating characterizations and help establish precision immunotherapy strategies for individual ccRCC patients.

Estimating DNA methylation potential energy landscapes from nanopore sequencing data

High-throughput third-generation nanopore sequencing devices have enormous potential for simultaneously observing epigenetic modifications in human cells over large regions of the genome. However, signals generated by these devices are subject to considerable noise that can lead to unsatisfactory detection performance and hamper downstream analysis. Here we develop a statistical method, CpelNano, for the quantification and analysis of 5mC methylation landscapes using nanopore data. CpelNano takes into account nanopore noise by means of a hidden Markov model (HMM) in which the true but unknown (“hidden”) methylation state is modeled through an Ising probability distribution that is consistent with methylation means and pairwise correlations, whereas nanopore current signals constitute the observed state. It then estimates the associated methylation potential energy function by employing the expectation-maximization (EM) algorithm and performs differential methylation analysis via permutation-based hypothesis testing. Using simulations and analysis of published data obtained from three human cell lines (GM12878, MCF-10A, and MDA-MB-231), we show that CpelNano can faithfully estimate DNA methylation potential energy landscapes, substantially improving current methods and leading to a powerful tool for the modeling and analysis of epigenetic landscapes using nanopore sequencing data.

Target-Specific Profiling of RNA m5C Methylation Level Using Amplicon Sequencing.

Mapping the position and quantifying the level of 5-methylcytosine (m5C) as a modification in different types of cellular RNA is an important objective in the field of epitranscriptomics. Bisulfite conversion has long been the gold standard for the detection of m5C in DNA, but it can also be applied to RNA. Here, we detail methods for bisulfite treatment of RNA, locus-specific PCR amplification, and detection of candidate sites by sequencing on the Illumina MiSeq platform.

Comprehensive Analysis of m5C RNA Methylation Regulator Genes in Clear Cell Renal Cell Carcinoma.

Background Recent research found that N5-methylcytosine (m5C) was involved in the development and occurrence of numerous cancers. However, the function and mechanism of m5C RNA methylation regulators in clear cell renal cell carcinoma (ccRCC) remains undiscovered. This study is aimed at investigating the predictive and clinical value of these m5C-related genes in ccRCC. Methods Based on The Cancer Genome Atlas (TCGA) database, the expression patterns of twelve m5C regulators and matched clinicopathological characteristics were downloaded and analyzed. To reveal the relationships between the expression levels of m5C-related genes and the prognosis value in ccRCC, consensus clustering analysis was carried out. By univariate Cox analysis and last absolute shrinkage and selection operator (LASSO) Cox regression algorithm, a m5C-related risk signature was constructed in the training group and further validated in the testing group and the entire cohort. Then, the predictive ability of survival of this m5C-related risk signature was analyzed by Cox regression analysis and nomogram. Functional annotation and single-sample Gene Set Enrichment Analysis (ssGSEA) were applied to further explore the biological function and potential signaling pathways. Furthermore, we performed qRT-PCR experiments and measured global m5C RNA methylation level to validate this signature in vitro and tissue samples. Results In the TCGA-KIRC cohort, we found significant differences in the expression of m5C RNA methylation-related genes between ccRCC tissues and normal kidney tissues. Consensus cluster analysis was conducted to separate patients into two m5C RNA methylation subtypes. Significantly better outcomes were observed in ccRCC patients in cluster 1 than in cluster 2. m5C RNA methylation-related risk score was calculated to evaluate the prognosis of ccRCC patients by seven screened m5C RNA methylation regulators (NOP2, NSUN2, NSUN3, NSUN4, NSUN5, TET2, and DNMT3B) in the training cohort. The AUC for the 1-, 2-, and 3-year survival in the training cohort were 0.792, 0.675, and 0.709, respectively, indicating that the risk signature had an excellent prognosis prediction in ccRCC. Additionally, univariate and multivariate Cox regression analyses revealed that the risk signature could be an independent prognostic factor in ccRCC. The results of ssGSEA suggested that the immune cells with different infiltration degrees between the high-risk and low-risk groups were T cells including follicular helper T cells, Th1_cells, Th2_cells, and CD8+_T_cells, and the main differences in immune-related functions between the two groups were the interferon response and T cell costimulation. In addition, qRT-PCR experiments confirmed our results in renal cell lines and tissue samples. Conclusions According to the seven selected regulatory factors of m5C RNA methylation, a risk signature associated with m5C methylation that can independently predict prognosis in patients with ccRCC was developed and further verified the predictive efficiency.

NSUN2 modified by SUMO-2/3 promotes gastric cancer progression and regulates mRNA m5C methylation

The 5-methylcytosine (m5C) RNA methyltransferase NSUN2 is involved in the regulation of cell proliferation and metastasis formation and is upregulated in multiple cancers. However, the biological significance of NSUN2 in gastric cancer (GC) and the modification of NSUN2 itself have not been fully investigated. Here, we analyzed the expression level of NSUN2 in tissue microarrays containing 403 GC tissues by immunohistochemistry. NSUN2 was upregulated in GC, and that it was a predictor of poor prognosis. NSUN2 promotes the proliferation, migration, and invasion of GC cells in vitro. We also demonstrated that small ubiquitin-like modifier (SUMO)-2/3 interacts directly with NSUN2 by stabilizing it and mediating its nuclear transport. This facilitates the carcinogenic activity of NSUN2. Furthermore, m5C bisulfite sequencing (Bis-seq) in NSUN2-deficient GC cells showed that m5C-methylated genes are involved in multiple cancer-related signaling pathways. PIK3R1 and PCYT1A may be the target genes that participate in GC progression. Our findings revealed a novel mechanism by which NSUN2 functions in GC progression. This may provide new treatment options for GC patients.

Rapid identification of methylase specificity (RIMS-seq) jointly identifies methylated motifs and generates shotgun sequencing of bacterial genomes.

DNA methylation is widespread amongst eukaryotes and prokaryotes to modulate gene expression and confer viral resistance. 5-Methylcytosine (m5C) methylation has been described in genomes of a large fraction of bacterial species as part of restriction-modification systems, each composed of a methyltransferase and cognate restriction enzyme. Methylases are site-specific and target sequences vary across organisms. High-throughput methods, such as bisulfite-sequencing can identify m5C at base resolution but require specialized library preparations and single molecule, real-time (SMRT) sequencing usually misses m5C. Here, we present a new method called RIMS-seq (rapid identification of methylase specificity) to simultaneously sequence bacterial genomes and determine m5C methylase specificities using a simple experimental protocol that closely resembles the DNA-seq protocol for Illumina. Importantly, the resulting sequencing quality is identical to DNA-seq, enabling RIMS-seq to substitute standard sequencing of bacterial genomes. Applied to bacteria and synthetic mixed communities, RIMS-seq reveals new methylase specificities, supporting routine study of m5C methylation while sequencing new genomes.

DNA methylation atlas and machinery in the developing and regenerating annelid Platynereis dumerilii

BackgroundMethylation of cytosines in DNA (5mC methylation) is a major epigenetic modification that modulates gene expression and constitutes the basis for mechanisms regulating multiple aspects of embryonic development and cell reprogramming in vertebrates. In mammals, 5mC methylation of promoter regions is linked to transcriptional repression. Transcription regulation by 5mC methylation notably involves the nucleosome remodeling and deacetylase complex (NuRD complex) which bridges DNA methylation and histone modifications. However, less is known about regulatory mechanisms involving 5mC methylation and their function in non-vertebrate animals. In this paper, we study 5mC methylation in the marine annelid worm Platynereis dumerilii, an emerging evolutionary and developmental biology model capable of regenerating the posterior part of its body post-amputation.ResultsUsing in silico and experimental approaches, we show that P. dumerilii displays a high level of DNA methylation comparable to that of mammalian somatic cells. 5mC methylation in P. dumerilii is dynamic along the life cycle of the animal and markedly decreases at the transition between larval to post-larval stages. We identify a full repertoire of mainly single-copy genes encoding the machinery associated with 5mC methylation or members of the NuRD complex in P. dumerilii and show that this repertoire is close to the one inferred for the last common ancestor of bilaterians. These genes are dynamically expressed during P. dumerilii development and regeneration. Treatment with the DNA hypomethylating agent Decitabine impairs P. dumerilii larval development and regeneration and has long-term effects on post-regenerative growth.ConclusionsOur data reveal high levels of 5mC methylation in the annelid P. dumerilii, highlighting that this feature is not specific to vertebrates in the bilaterian clade. Analysis of DNA methylation levels and machinery gene expression during development and regeneration, as well as the use of a chemical inhibitor of DNA methylation, suggest an involvement of 5mC methylation in P. dumerilii development and regeneration. We also present data indicating that P. dumerilii constitutes a promising model to study biological roles and mechanisms of DNA methylation in non-vertebrate bilaterians and to provide new knowledge about evolution of the functions of this key epigenetic modification in bilaterian animals.

NSUN2-mediated RNA 5-methylcytosine promotes esophageal squamous cell carcinoma progression via LIN28B-dependent GRB2 mRNA stabilization

5-Methylcytosine (m5C) is a posttranscriptional RNA modification participating in many critical bioprocesses, but its functions in human cancer remain unclear. Here, by detecting the transcriptome-wide m5C profiling in esophageal squamous cell carcinoma (ESCC), we showed increased m5C methylation in ESCC tumors due to the overexpressed m5C methyltransferase NSUN2. Aberrant expression of NSUN2 was positively regulated by E2F Transcription Factor 1 (E2F1). High NSUN2 levels predicted poor survival of ESCC patients. Moreover, silencing NSUN2 suppressed ESCC tumorigenesis and progression in Nsun2 knockout mouse models. Mechanistically, NSUN2 induced m5C modification of growth factor receptor-bound protein 2 (GRB2) and stabilized its mRNA, which was mediated by a novel m5C mediator, protein lin-28 homolog B (LIN28B). Elevated GRB2 levels increased the activation of PI3K/AKT and ERK/MAPK signalling. These results demonstrate that NSUN2 enhances the initiation and progression of ESCC via m5C-LIN28B dependent stabilization of GRB2 transcript, providing a promising epitranscriptomic-targeted therapeutic strategy for ESCC.

Comprehensive Analysis of 5-Methylcytosine Profiles of Messenger RNA in Human High-Grade Serous Ovarian Cancer by MeRIP Sequencing.

BackgroundAccumulating evidence has indicated that methylation status is closely related to tumourigenesis and a few aggressive features of diverse cancers. However, as an important methylation regulation modification, the distribution of 5-methylcytosine (m5C) in high-grade serous ovarian cancer (HGSOC) remains unclear.Materials and MethodsWe collected three pairs of human HGSOC tissues and adjacent non-tumour tissues to analyse the transcriptome-wide m5C methylation of messenger RNAs (mRNAs) by methylated RNA immunoprecipitation sequencing. Gene ontology (GO) enrichment analysis and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis were performed to eExplore the potential biological functions of these genes and important cancer pathways. We used immunohistochemistry to analyse the expression of the m5C modification regulatory gene MAP2K3 in 80 HGSOC tissue samples, and their associations with clinical parameters were analyzed using the Spearman-rho test. Univariate and multivariate Cox regression analyses were performed to identify potential prognostic factors. Kaplan–Meier analysis was performed to analyze overall survival.ResultsWe identified 2050 dysregulated m5C peaks, 1767 of which were significantly upregulated, while 283 were significantly downregulated. GO enrichment analysis showed that genes altered by the m5C peak played a key role in system development, transporter complex, and transporter activity. KEGG pathway analysis revealed that these genes were enriched in some important pathways in cancer regulation, such as inflammatory mediator regulation of the TRP channels pathway, Wnt signalling pathway, and focal adhesion pathways. In addition, through joint analysis of MeRIP-seq and RNA-seq data, we identified 125 differentially methylated m5C peaks and synchronous differentially expressed genes. These genes play key roles in cell growth, maintenance, plasma membranes, and cell adhesion molecule activity. Immunohistochemical staining results showed that high expression of MAP2K3 was significantly correlated with CA125 level (p < 0.001), tumour size (p = 0.001), lymph node metastasis (p = 0.008), depth of myometrial invasion (p < 0.001), and FIGO stage (p < 0.001), indicating a poor prognosis.ConclusionOur results reveal the different distribution patterns of m5C in HGSOC and adjacent tissues and the possible involvement of m5C in HGSOC cell functions. Our study provides new insights into the epi-transcriptomic dysregulation of m5C in the tumourigenesis of HGSOC.

The methylome of the model arbuscular mycorrhizal fungus, Rhizophagus irregularis, shares characteristics with early diverging fungi and Dikarya

Early-diverging fungi (EDF) are distinct from Dikarya and other eukaryotes, exhibiting high N6-methyldeoxyadenine (6mA) contents, rather than 5-methylcytosine (5mC). As plants transitioned to land the EDF sub-phylum, arbuscular mycorrhizal fungi (AMF; Glomeromycotina) evolved a symbiotic lifestyle with 80% of plant species worldwide. Here we show that these fungi exhibit 5mC and 6mA methylation characteristics that jointly set them apart from other fungi. The model AMF, R. irregularis, evolved very high levels of 5mC and greatly reduced levels of 6mA. However, unlike the Dikarya, 6mA in AMF occurs at symmetrical ApT motifs in genes and is associated with their transcription. 6mA is heterogeneously distributed among nuclei in these coenocytic fungi suggesting functional differences among nuclei. While far fewer genes are regulated by 6mA in the AMF genome than in EDF, most strikingly, 6mA methylation has been specifically retained in genes implicated in components of phosphate regulation; the quintessential hallmark defining this globally important symbiosis.

Identification of 5-methylcytosine-related signature for predicting prognosis in ovarian cancer

BackgroundOvarian cancer is one of the most common malignancies often resulting in a poor prognosis. 5-methylcytosine (m5C) is a common epigenetic modification with roles in eukaryotes. However, the expression and function of m5C regulatory factors in ovarian cancer remained unclear.ResultsTwo molecular subtypes with different prognostic and clinicopathological features were identified based on m5C regulatory factors. Meanwhile, functional annotation showed that in the two subtypes, 452 differentially expressed genes were significantly related to the malignant progression of ovarian cancer. Subsequently, four m5C genes were screened to construct a risk marker predictive of overall survival and indicative of clinicopathological features of ovarian cancer, also the robustness of the risk marker was verified in external dataset and internal validation set. multifactorial cox regression analysis and nomogram demonstrated that risk score was an independent prognostic factor for ovarian cancer prognosis.ConclusionIn conclusion, our results revealed that m5C-related genes play a critical role in tumor progression in ovarian cancer. Further detection of m5C methylation could provide a novel targeted therapy for treating ovarian cancer.

TRDMT1 participates in the DNA damage repair of granulosa cells in premature ovarian failure.

The molecular mechanisms underlying premature ovarian failure, which seriously impacts the physical and psychological health of patients, are not fully understood. Here, we present the role of TRDMT1 in reactive oxygen species-induced granulosa cells death, which is considered an important cause of premature ovarian failure. We found that reactive oxygen species were increased in a H2O2 dose-dependent manner and accompanied by the nuclear shuttling of TRDMT1, increased DNA damage and increased apoptosis of granulosa cells. In addition, reactive oxygen species-induced granulosa cells apoptosis could be prevented by the antioxidant N-acetylcysteine or overexpression of TRDMT1. Furthermore, DNA repair following reactive oxygen species induction was severely impaired/enhanced in TRDMT1 mutants, which exhibited reduced/increased RNA m5C methylation activity. Altogether, our results reveal a novel role of TRDMT1 in the regulation of premature ovarian failure through the repair of reactive oxygen species-triggered DNA damage in granulosa cells and provide an improved understanding of the mechanisms underlying granulosa cells apoptosis, which could potentially be useful for future clinical treatments of premature ovarian failure.

M5C regulator-mediated methylation modification patterns and tumor microenvironment infiltration characterization in lung adenocarcinoma.

BackgroundIn recent years, immunotherapy has made great progress, and the regulatory role of epigenetics has been verified. However, the role of 5-methylcytosine (m5C) in the tumor microenvironment (TME) and immunotherapy response remains unclear.MethodsBased on 11 m5C regulators, we evaluated the m5C modification patterns of 572 lung adenocarcinoma (LUAD) patients. The m5C score was constructed by principal component analysis (PCA) algorithms in order to quantify the m5C modification pattern of individual LUAD patients.ResultsTwo m5C methylation modification patterns were identified according to 11 m5C regulators. The two patterns had a remarkably distinct TME immune cell infiltration characterization. Next, 226 differentially expressed genes (DEGs) related to the m5C phenotype were screened. Patients were divided into three different gene cluster subtypes based on these genes, which had different TME immune cell infiltration and prognosis characteristics. The m5C score was constructed to quantify the m5C modification pattern of individual LUAD patients. We found that the high m5C score group had a better prognosis. The role of the m5C score in predicting prognosis was also verified in the dataset GSE31210.ConclusionsOur study revealed that m5C modification played a significant role in TME regulation of LUAD. Investigation of the m5C regulation mode may have some implications for tumor immunotherapy in the future.

Identification of Expression Patterns and Potential Prognostic Significance of m5C-Related Regulators in Head and Neck Squamous Cell Carcinoma.

5-Methylcytosine (m5C) methylation is a major epigenetic technique of RNA modification and is dynamically mediated by m5C “writers,” “erasers,” and “readers.” m5C RNA modification and its regulators are implicated in the onset and development of many tumors, but their roles in head and neck squamous cell carcinoma (HNSCC) have not yet been completely elucidated. In this study, we examined expression patterns of core m5C regulators in the publicly available HNSCC cohort via bioinformatic methods. The differentially expressed m5C regulators could divide the HNSCC cohort into four subgroups with distinct prognostic characteristics. Furthermore, a three-gene expression signature model, comprised of NSUN5, DNMT1, and DNMT3A, was established to identify individuals with a high or low risk of HNSCC. To explore the underlying mechanism in the prognosis of HNSCC, screening of differentially expressed genes, followed by the analysis of functional and pathway enrichment, from individuals with high- or low-risk HNSCC was performed. The results revealed a critical role for m5C RNA modification in two aspects of HNSCC: (1) dynamic m5C modification contributes to the regulation of HNSCC progression and (2) expression patterns of NSUN5, DNMT1, and DNMT3A help to predict the prognosis of HNSCC.

Detection of cytosine methylation in Burkholderia cenocepacia by single-molecule real-time sequencing and whole-genome bisulfite sequencing.

Research on prokaryotic epigenetics, the study of heritable changes in gene expression independent of sequence changes, led to the identification of DNA methylation as a versatile regulator of diverse cellular processes. Methylation of adenine bases is often linked to regulation of gene expression in bacteria, but cytosine methylation is also frequently observed. In this study, we present a complete overview of the cytosine methylome in Burkholderia cenocepacia, an opportunistic respiratory pathogen in cystic fibrosis patients. Single-molecule real-time (SMRT) sequencing was used to map all 4mC-modified cytosines, as analysis of the predicted MTases in the B. cenocepacia genome revealed the presence of a 4mC-specific phage MTase, M.BceJII, targeting GGCC sequences. Methylation motif GCGGCCGC was identified, and out of 6850 motifs detected across the genome, 2051 (29.9 %) were methylated at the fifth position. Whole-genome bisulfite sequencing (WGBS) was performed to map 5mC methylation and 1635 5mC-modified cytosines were identified in CpG motifs. A comparison of the genomic positions of the modified bases called by each method revealed no overlap, which confirmed the authenticity of the detected 4mC and 5mC methylation by SMRT sequencing and WGBS, respectively. Large inter-strain variation of the 4mC-methylated cytosines was observed when B. cenocepacia strains J2315 and K56-2 were compared, which suggests that GGCC methylation patterns in B. cenocepacia are strain-specific. It seems likely that 4mC methylation of GGCC is not involved in regulation of gene expression but rather is a remnant of bacteriophage invasion, in which methylation of the phage genome was crucial for protection against restriction-modification systems of B. cenocepacia.

Expression and prognostic characteristics of m5 C regulators in low-grade glioma.

Glioma is the most common intracranial malignant tumour. A clear diagnosis and molecular targeted therapy are of great significance for improving the survival time and quality of life of patients with low‐grade glioma. 5‐methylcytosine methylation is one of the ways of RNA modification, but there are limited studies on the role of m5C methylation of low‐grade glioma. Single‐nucleotide variant, RNA expression matrix and corresponding clinical data of low‐grade glioma came from public database. The single‐nucleotide variant and expression of m5C regulators were estimated. A prognostic model based on m5C regulators was constructed by Cox regression. Potential functions of these molecules were assessed by gene set enrichment analysis. DNMT3A mutation was the most frequent among the m5C regulators in low‐grade glioma. NSUN3, TET2, TRDMT1, ALYREF, DNMT3B, DNMT1, NOP2 and NSUN2 were up‐regulated. One prognostic model was constructed which had a strong predictive power for the overall survival of low‐grade glioma. We studied the expression and prognostic characteristics of m5C regulators in low‐grade glioma, supplied biomarkers for the diagnosis and prognosis and provided the foundation for the study of the pathogenesis of low‐grade glioma.

Novel insights into the role of 5-Methylcytosine RNA methylation in human abdominal aortic aneurysm.

Background: It remains largely unclear about the function of 5-methylcytosine (m5C) RNA modification in the context of abdominal aortic aneurysm (AAA). In this regard, the present work focused on investigating m5C RNA methylation and related modulator expression levels in AAA. Materials and methods: To this end, we quantified the m5C methylation levels in AAA tissues (n = 32) and normal aortic tissues (n = 12) to examine the mRNA m5C status and m5C modulator expression at mRNA and protein levels. Meanwhile, modulator localization within AAA tissue samples was detected by immunohistochemistry (IHC). Moreover, RNA immunoprecipitation-sequencing (RIP-seq) was also used to analyze the lncRNAs and mRNA binding to Aly/REF, as an m5C reader. Results: m5C expression markedly elevated in AAA in comparison with normal aortic samples in the AAA cases. The major 5-methylcytosine modulators, including NSUN2, NSUN5, and Aly/REF, which represented the major parameters related to the abnormal m5C modification level, were observed up-regulating in AAA tissues at both protein and mRNA levels. In addition, NSUN2 mRNA level remarkably related to Aly/REF expression, and they were co-expressed in the same cells in AAA group. Regarding the cellular location, Aly/REF was associated with inflammatory (CD45+, CD3+) infiltrates. Simultaneously, after screening for reads in AAA tissue compare with anti-Aly/REF group relative to IgG as control, we obtained totally 477 differentially expressed Aly/REF-binding lncRNAs and 369 differentially expressed Aly/REF-binding mRNAs in AAA tissue. The functions of Aly/REF-interacting lncRNA were involved in immune system process and macrophages infiltration. Through regulatory network (lncRNA-mRNA) analysis, our findings predicted the potential mechanism of Aly/REF-induced lncBCL2L1 and Aly/REF-lncFHL1 axis in AAA and inspire the understanding of m5C and lncRNA in AAA. Conclusions: This study is the first to examine m5A modification within human AAA samples. Our results indicate that m5C modulators, namely, Aly/REF and NUSN2, play vital parts in the human AAA pathogenic mechanism, which shed new lights on the function of m5C modification within AAA. Taken together, findings in this work offer a possible RNA methylation modification mechanism within clinical AAA.

The role of RNA m5C modification in cancer metastasis.

Epigenetic modification plays a crucial regulatory role in the biological processes of eukaryotic cells. The recent characterization of DNA and RNA methylation is still ongoing. Tumor metastasis has long been an unconquerable feature in the fight against cancer. As an inevitable component of the epigenetic regulatory network, 5-methylcytosine is associated with multifarious cellular processes and systemic diseases, including cell migration and cancer metastasis. Recently, gratifying progress has been achieved in determining the molecular interactions between m5C writers (DNMTs and NSUNs), demethylases (TETs), readers (YTHDF2, ALYREF and YBX1) and RNAs. However, the underlying mechanism of RNA m5C methylation in cell mobility and metastasis remains unclear. The functions of m5C writers and readers are believed to regulate gene expression at the post-transcription level and are involved in cellular metabolism and movement. In this review, we emphatically summarize the recent updates on m5C components and related regulatory networks. The content will be focused on writers and readers of the RNA m5C modification and potential mechanisms in diseases. We will discuss relevant upstream and downstream interacting molecules and their associations with cell migration and metastasis.

Preliminary Exploration and Analysis of m5C Methylation in Immune Infiltration and Mutation Prognosis in Cervical Cancer

Preliminary Exploration and Analysis of m5C Methylation in Immune Infiltration and Mutation Prognosis in Cervical Cancer

Sequence- and structure-selective mRNA m5C methylation by NSUN6 in animals.

mRNA m5C, which has recently been implicated in the regulation of mRNA mobility, metabolism and translation, plays important regulatory roles in various biological events. Two types of m5C sites are found in mRNAs. Type I m5C sites, which contain a downstream G-rich triplet motif and are computationally predicted to be located at the 5′ end of putative hairpin structures, are methylated by NSUN2. Type II m5C sites contain a downstream UCCA motif and are computationally predicted to be located in the loops of putative hairpin structures. However, their biogenesis remains unknown. Here we identified NSUN6, a methyltransferase that is known to methylate C72 of tRNAThr and tRNACys, as an mRNA methyltransferase that targets Type II m5C sites. Combining the RNA secondary structure prediction, miCLIP, and results from a high-throughput mutagenesis analysis, we determined the RNA sequence and structural features governing the specificity of NSUN6-mediated mRNA methylation. Integrating these features into an NSUN6-RNA structural model, we identified an NSUN6 variant that largely loses tRNA methylation but retains mRNA methylation ability. Finally, we revealed a weak negative correlation between m5C methylation and translation efficiency. Our findings uncover that mRNA m5C is tightly controlled by an elaborate two-enzyme system, and the protein-RNA structure analysis strategy established may be applied to other RNA modification writers to distinguish the functions of different RNA substrates of a writer protein.