Multifaceted Functions and Novel Insight Into the Regulatory Role of RNA N6-Methyladenosine Modification in Musculoskeletal Disorders

RNA modifications have emerged as key regulators of transcript expression in diverse physiological and pathological processes. As one of the most prevalent types of RNA modifications, N⁶-methyladenosine (m⁶A) has become the highlight in modulation of various diseases through interfering RNA splicing, translation, nuclear export, and decay. In many cases, the detailed functions of m⁶A in cellular processes and diseases remain unclear. Notably, recent studies have determined the relationship between m⁶A modification and musculoskeletal disorders containing osteosarcoma, osteoarthritis, rheumatoid arthritis, osteoporosis, etc. Herein, this review comprehensively summarizes the recent advances of m⁶A modification in pathogenesis and progression of musculoskeletal diseases. Specifically, the underlying molecular mechanisms, detection technologies, regulatory functions, clinical implications, and future perspectives of m⁶A in musculoskeletal disorders are discussed, with the aim to provide a novel insight into their association.

Regulation of RNA N6-methyladenosine modification and its emerging roles in skeletal muscle development

N6-methyladenosine (m6A) is one of the most widespread and highly conserved chemical modifications in cellular RNAs of eukaryotic genomes. Owing to the development of high-throughput m6A sequencing, the functions and mechanisms of m6A modification in development and diseases have been revealed. Recent studies have shown that RNA m6A methylation plays a critical role in skeletal muscle development, which regulates myoblast proliferation and differentiation, and muscle regeneration. Exploration of the functions of m6A modification and its regulators provides a deeper understanding of the regulatory mechanisms underlying skeletal muscle development. In the present review, we aim to summarize recent breakthroughs concerning the global landscape of m6A modification in mammals and examine the biological functions and mechanisms of enzymes regulating m6A RNA methylation. We describe the interplay between m6A and other epigenetic modifications and highlight the regulatory roles of m6A in development, especially that of skeletal muscle. m6A and its regulators are expected to be targets for the treatment of human muscle-related diseases and novel epigenetic markers for animal breeding in meat production.

Regulatory Role of the RNA N6-Methyladenosine Modification in Immunoregulatory Cells and Immune-Related Bone Homeostasis Associated With Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease for which the etiology has not been fully elucidated. Previous studies have shown that the development of RA has genetic and epigenetic components. As one of the most highly abundant RNA modifications, the N⁶-methyladenosine (m⁶A) modification is necessary for the biogenesis and functioning of RNA, and modification aberrancies are associated with various diseases. However, the specific functions of m⁶A in the cellular processes of RA remain unclear. Recent studies have revealed the relationship between m⁶A modification and immune cells associated with RA. Therefore, in this review, we focused on discussing the functions of m⁶A modification in the regulation of immune cells and immune-related bone homeostasis associated with RA. In addition, to gain a better understanding of the progress in this field of study and provide the proper direction and suggestions for further study, clinical application studies of m⁶A modification were also summarized.

ATXN2-mediated translation of TNFR1 promotes esophageal squamous cell carcinoma via m6A-dependent manner

N⁶-methyladenosine (m⁶A) is the most prevalent RNA modification, and the effect of its dysregulation on esophageal squamous cell carcinoma (ESCC) development remains unclear. Here, by performing transcriptome-wide m⁶A sequencing in 16 ESCC tissue samples, we identified the key roles of m⁶A in TNFRSF1A (also known as TNFR1)-mediated MAPK and NF-κB activation in ESCC. Mechanistically, a functional protein involved in m⁶A methylation, ATXN2, is identified that augments the translation of TNFRSF1A by binding to m⁶A-modified TNFRSF1A mRNA. Upregulation of the TNFRSF1A protein level, a vital upstream switch for TNFRSF1A-mediated signaling events, activates the NF-κB and MAPK pathways and thus promotes ESCC development. Furthermore, TNFRSF1A m⁶A modifications and protein levels are upregulated in ESCC, and high levels of TNFRSF1A m⁶A and protein are correlated with poor ESCC patient survival. These results collectively indicate that the m⁶A-TNFRSF1A axis is critical for ESCC development and thus may serve as a potential druggable target.

Multiplexed magnetic beads-assisted amperometric bioplatforms for global detection of methylations in nucleic acids

This work reports the first electrochemical bioplatform developed for the multidetection of 5-methylcytosine (5-mC) and 5-hydroxymethylcytosine (5-hmC) in DNA, DNA N6-methyladenine (6mA) and RNA N6-methyladenosine (m6A) methylations at global level. Direct competitive immunoassays were implemented on the surface of magnetic beads (MBs) and optimized for the single amperometric determination of different targets varying in length, sequence and number of methylations on screen-printed carbon electrodes. After evaluating the sensitivity and selectivity of such determinations and the confirmation of no cross-reactivity, a multiplexed disposable platform allowing the simultaneous determination of the mentioned four methylation events in only 45 min has been prepared. The multiplexed bioplatform was successfully applied to the determination of m6A in cellular total RNA and of 5-mC, 5-hmC and 6mA in genomic DNA extracted from tissues. The developed bioplatform showed its usefulness to discriminate the aggressiveness of cancerous cells and between healthy and tumor tissues of colorectal cancer patients.

Gene signature of m6A-related targets to predict prognosis and immunotherapy response in ovarian cancer

PURPOSE

The aim of the study was to construct a risk score model based on m6A-related targets to predict overall survival and immunotherapy response in ovarian cancer.

METHODS

The gene expression profiles of 24 m6A regulators were extracted. Survival analysis screened 9 prognostic m6A regulators. Next, consensus clustering analysis was applied to identify clusters of ovarian cancer patients. Furthermore, 47 phenotype-related differentially expressed genes, strongly correlated with 9 prognostic m6A regulators, were screened and subjected to univariate and the least absolute shrinkage and selection operator (LASSO) Cox regression. Ultimately, a nomogram was constructed which presented a strong ability to predict overall survival in ovarian cancer.

RESULTS

CBLL1, FTO, HNRNPC, METTL3, METTL14, WTAP, ZC3H13, RBM15B and YTHDC2 were associated with worse overall survival (OS) in ovarian cancer. Three m6A clusters were identified, which were highly consistent with the three immune phenotypes. What is more, a risk model based on seven m6A-related targets was constructed with distinct prognosis. In addition, the low-risk group is the best candidate population for immunotherapy.

CONCLUSION

We comprehensively analyzed the m6A modification landscape of ovarian cancer and detected seven m6A-related targets as an independent prognostic biomarker for predicting survival. Furthermore, we divided patients into high- and low-risk groups with distinct prognosis and select the optimum population which may benefit from immunotherapy and constructed a nomogram to precisely predict ovarian cancer patients' survival time and visualize the prediction results.

RNA N6-methyladenosine modification mediates downregulation of NR4A1 to facilitate malignancy of cervical cancer

BACKGROUND

N⁶-methyladenosine is the most abundant eukaryotic mRNA modification and alters a wide range of cellular processes in cancer. Therefore, defining the molecular details are critical for understanding the regulatory mechanism of m⁶A modification.

RESULTS

We found that METTL3, a core m⁶A methyltransferase component, is upregulated and functions as an oncogene in cervical cancer. Mechanistically, METTL3 induces the degradation of m⁶A-modified transcripts of NR4A1 though YTHDF2-DDX6 pathway. In addition, NR4A1 overexpression attenuates the malignant progression through recruiting the LSD1/HDAC1/CoREST transcriptional repression complex to AKT1 promoter.

CONCLUSIONS

Our findings reveal that m⁶A regulates cervical cancer cellular progression through manipulating NR4A1 pathway.

GMEB2 Promotes the Growth of Colorectal Cancer by Activating ADRM1 Transcription and NF-κB Signalling and Is Positively Regulated by the m6A Reader YTHDF1

Transcription factors are frequently aberrantly reactivated in various cancers, including colorectal cancer (CRC). However, as a transcription factor, the role of GMEB2 in cancer is still unclear, and further studies are needed. Here, we aimed to identify the function and mechanism of GMEB2 in regulating the malignant progression of CRC. GMEB2 was found to be highly expressed in online data analyses. We demonstrated that GMEB2 was markedly upregulated at both the mRNA and protein levels in CRC cells and tissues. GMEB2 knockdown inhibited CRC cell growth in vitro and in vivo. Mechanistically, as a transcription factor, GMEB2 transactivated the ADRM1 promoter to increase its transcription. Rescue experiments showed that ADRM1 downregulation partially reversed the promoting effects of GMEB2 on CRC growth in vitro. Moreover, the GMEB2/ADRM1 axis induced nuclear translocation of NF-κB, thus activating NF-κB signalling. Finally, we further revealed that YTHDF1 recognized and bound to the m⁶A site on GMEB2 mRNA, which enhanced its stability. Taken together, our findings reveal the crucial role and regulatory mechanism of GMEB2 in CRC for the first time and provide a novel potential therapeutic target for CRC therapy.

RNA m6A Alterations Induced by Biomineralization Nanoparticles: A Proof-of-Concept Study of Epitranscriptomics for Nanotoxicity Evaluation

Although various strategies have been included in nanotoxicity evaluation, epitranscriptomics has rarely been integrated into this field. In this proof-of-concept study, N6-methyladenosine (m⁶A) changes of mRNA in HEK293T cells induced by three bovine serum albumin (BSA)-templated Au, CuS and Gd₂O₃ nanoparticles are systematically explored, and their possible biological mechanisms are preliminarily investigated. It has been found that all the three BSA-templated nanoparticles can reduce m⁶A levels, and the genes with reduced m⁶A are enriched for TGF-beta signaling, which is critical for cell proliferation, differentiation and apoptosis. Further results indicate that abnormal aggregation of m⁶A-related enzymes at least partly account for the nanoparticle-induced epitranscriptomic changes. These findings demonstrate that epitranscriptomics analysis can provide an unprecedented landscape of the biological effect induced by nanomaterials, which should be involved in the nanotoxicity evaluation to promote the potential clinical translation of nanomaterials.

m6A regulator-mediated methylation modification patterns and immune microenvironment infiltration characterization in osteoarthritis

Osteoarthritis (OA) is a common disease in orthopedics. RNA N6-methyladenosine (m6A) exerts an essential effect in a variety of biological processes in the eukaryotes. In this study, we determined the effect of m6A regulators in the OA along with performing the subtype classification. Differential analysis of OA and normal samples in the database of Gene Expression Omnibus identified 9 significantly differentially expressed m6A regulators. These regulators were monitored by a random forest algorithm so as to evaluate the risk of developing OA disease. On the basis of these 9 moderators, a nomogram was established. The results of decision curve analysis suggested that the patients could benefit from a nomogram model. The OA sample was classified as 2 m6A models through a consensus clustering algorithm in accordance with these 9 regulators. These 2 m6A patterns were then assessed with principal component analysis. We also determined the m6A scores for the 2 m6A patterns and their correlation with immune infiltration. The results indicated that type A had a higher m6A score than type B. Thus, we suggest that the m6A pattern may provide a new approach for diagnose and provide novel ideas for molecular targeted therapy of OA.

circBRAF promotes the progression of triple-negative breast cancer through modulating methylation by recruiting KDM4B to histone H3K9me3 and IGF2BP3 to mRNA

Understanding the molecular characteristics of triple-negative breast cancer (TNBC) and developing more tailored treatment approaches is crucial. Circular RNAs (circRNAs), as potential therapeutic targets, remain largely unexplored in TNBC. This study utilized circRNA microarray analysis to determine the expression of circRNAs in TNBC, analyzing nine patient specimens. The characteristics of circBRAF were examined using divergent PCR primers, Sanger sequencing, fluorescence in situ hybridization (FISH) analysis, and the application of RNase and actinomycin D. The biological function of circBRAF in TNBC was further investigated through colony formation, tube formation, and transwell assays. Crucially, the mechanisms underlying the effects of circBRAF on TNBC progression were explored via RNA immunoprecipitation sequencing (RIP-seq) data, MS2 pulldown, RNA sequencing (RNA-seq) analysis, circBRAF knockdown, histone H3K9me3 modification, and Chromatin Isolation by RNA Purification (ChIRP) tests followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). We focused particularly on hsa_circ_0007178, produced from exons 4-13 of the oncogene BRAF. Functional experiments revealed that circBRAF is crucial for the development of TNBC, with its knockdown preventing angiogenesis, metastasis, and cell division in vitro. Mechanistically, circBRAF interacts with KDM4B and IGF2BP3, promoting TNBC growth. Interaction of circBRAF with IGF2BP3 increased the expression of VCAN, FN1, CDCA3, or B4GALT3 by controlling mRNA stability through RNA N6-methyladenosine (m6A) modification. Furthermore, circBRAF upregulated the expression of ADAMTS14 and MMP9 through recruitment of KDM4B to enhance respective H3K9me3 modification. Furthermore, overexpression of circBRAF was able to overcome the inhibitory effects of siKDM4B and siIGF2BP3 on cell migration and invasion. Our findings suggest that circBRAF may act as an oncogene in TNBC through its specific interactions with KDM4B and IGF2BP3, implying that circBRAF could serve as a potentially effective novel therapeutic target for TNBC.

The m6A methylation landscape, molecular characterization and clinical relevance in prostate adenocarcinoma

Background

Despite the recent progress of therapeutic strategies in treating prostate cancer (PCa), the majority of patients still eventually relapse, experiencing dismal outcomes. Therefore, it is of utmost importance to identify novel viable targets to increase the effectiveness of treatment. The present study aimed to investigate the potential relationship between N6-methyladenosine (m6A) RNA modification and PCa development and determine its clinical relevance.

Methods

Through systematic analysis of the TCGA database and other datasets, we analyzed the gene expression correlation and mutation profiles of m6A-related genes between PCa and normal tissues. Patient samples were divided into high- and low-risk groups based on the results of Least Absolute Shrinkage and Selection Operator (LASSO) Cox analysis. Subsequently, differences in biological processes and genomic characteristics of the two risk groups were determined, followed by functional enrichment analysis and gene set enrichment (GSEA) analysis. Next, we constructed the protein-protein interaction (PPI) network of differentially expressed genes between patients in high- and low-risk groups, along with the mRNA-miRNA-lncRNA network. The correlation analysis of tumor-infiltrating immune cells was further conducted to reveal the differences in immune characteristics between the two groups.

Results

A variety of m6A-related genes were identified to be differentially expressed in PCa tissues as compared with normal tissues. In addition, the PPI network contained 278 interaction relationships and 34 m6A-related genes, and the mRNA-miRNA-lncRNA network contained 17 relationships, including 91 miRNAs. Finally, the immune characteristics analysis showed that compared with the low-risk group, the levels of M1 and M2 macrophages in the high-risk group significantly increased, while the levels of mast cells resting and T cells CD4 memory resting significantly decreased.

Conclusions

This study provides novel findings that can further the understanding of the role of m6A methylation during the progression of PCa, which may facilitate the invention of targeted therapeutic drugs.

The molecular characteristics in different procedures of spermatogenesis

Spermatogenesis is a multistep biological process. In addition to somatic cells, it involves the orderly differentiation of dozens of spermatogenic cells. In this process, the regulatory networks between different spermatogenic cell populations are significantly different. RNA m6A regulators and miRNAs have been found to be closely related to spermatogenesis in recent years, and they are an important part of the above regulatory networks. Understanding gene expression and its rules in different spermatogenic cell populations will help in the in-depth exploration of their detailed roles in spermatogenesis. This study collected a public dataset of nonobstructive azoospermia (NOA). Based on the Johnson score, the testicular samples of NOA were divided into three types, Sertoli-cell only syndrome, meiotic arrest and postmeiotic arrest, which represented the loss of three germ cell populations, including whole spermatogenic cells, postmeiotic spermatogenic cells, and a mixture of late spermatids and spermatozoa, respectively. The aforementioned three types of testis data were compared with normal testis data, and the molecular expression characteristics of the abovementioned three germ cell populations were obtained. Our study showed that different germ cell populations have different active molecules and their pathways. In addition, RNA m6A regulators, including METTL3, IGF2BP2 and PRRC2A, and miRNAs, including hsa-let-7a-2, hsa-let-7f-1, hsa-let-7g, hsa-miR-15a, hsa-miR-197, hsa-miR-21, hsa-miR-30e, hsa-miR-32, hsa-miR-503 and hsa-miR-99a, also presented regulatory roles in almost all germ cells.

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

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

The involvement of RNA N6-methyladenosine and histone methylation modification in decidualization and endometriosis-associated infertility

Defective decidualization of endometrial stromal cells (ESCs) in endometriosis (EM) patients leads to inadequate endometrial receptivity and EM-associated infertility. Hypoxia is an inevitable pathological process of EM and participates in deficient decidualization of the eutopic secretory endometrium. Enhancer of zeste homology 2 (EZH2) is a methyltransferase which catalyses H3K27Me3, leading to decreased expression levels of target genes. Although EZH2 expression is low under normal decidualization, it is abundantly increased in the eutopic secretory endometrium of EM and is induced by hypoxia. Chromatin immunoprecipitation-PCR results revealed that decidua marker IGFBP1 is a direct target of EZH2, partially explaining the increased levels of histone methylation modification in defected decidualization of EM. To mechanism controlling this, we examined the effects of hypoxia on EZH2 and decidualization. EZH2 mRNA showed decreased m6 A modification and increased expression levels under hypoxia and decidualization combined treatment. Increased EZH2 expression was due to the increased expression of m6 A demethylase ALKBH5 and decreased expression of the m6 A reader protein YTHDF2. YTHDF2 directly bind to the m6 A modification site of EZH2 to promote EZH2 mRNA degradation in ESCs. Moreover, selective Ezh2 depletion in mouse ESCs increased endometrial receptivity and improved mouse fertility by up-regulating decidua marker IGFBP1 expression. This is the first report showing that YTHDF2 can act as a m6 A reader to promote decidualization by decreasing the stability of EZH2 mRNA and further increasing the expression of IGFBP1 in ESCs. Taken together, our findings highlight the critical role of EZH2/H3K27Me3 in decidualization and reveal a novel epigenetic mechanism by which hypoxia can suppress EM decidualization by decreasing the m6 A modification of EZH2 mRNA.

m6A methylation modification and immune infiltration analysis in osteonecrosis of the femoral head

Osteonecrosis of the femoral head (ONFH) is a elaborate hip disease characterized by collapse of femoral head and osteoarthritis. RNA N6-methyladenosine (m6A) plays a crucial role in a lot of biological processes within eukaryotic cells. However, the role of m6A in the regulation of ONFH remains unclear. In this study, we identified the m6A regulators in ONFH and performed subtype classification. We identified 7 significantly differentially expressed m6A regulators through the analysis of differences between ONFH and normal samples in the Gene Expression Omnibus (GEO) database. A random forest algorithm was employed to monitor these regulators to assess the risk of developing ONFH. We constructed a nomogram based on these 7 regulators. The decision curve analysis suggested that patients can benefit from the nomogram model. We classified the ONFH samples into two m6A models according to these 7 regulators through consensus clustering algorithm. After that, we evaluated those two m6A patterns using principal component analysis. We assessed the scores of those two m6A patterns and their relationship with immune infiltration. We observed a higher m6A score of type A than that of type B. Finally, we performed a cross-validation of crucial m6A regulatory factors in ONFH using external datasets and femoral head bone samples. In conclusion, we believed that the m6A pattern could provide a novel diagnostic strategy and offer new insights for molecularly targeted therapy of ONFH.

Insights into RNA N6-methyladenosine in Glucose and Lipid Metabolic Diseases and Their Therapeutic Strategies

The incidence of glucose and lipid metabolism diseases, including type 2 diabetes, obesity, metabolic syndrome, and nonalcoholic fatty liver disease, is rising, which places an enormous burden on people around the world. However, the mechanism behind these disorders remains incompletely understood. N6-methyladenosine (m6A) is 1 type of posttranscriptional RNA modification, and research has shown that it plays a crucial role in several metabolic diseases. m6A methylation is reversibly and dynamically regulated by methyltransferases (writers), demethylases (erasers), and m6A binding proteins (readers). Dysregulation of RNA m6A modification is related to different metabolic processes. Targeting RNA m6A methylation is a potential treatment strategy for these chronic metabolic diseases. This review discusses studies on RNA m6A modification in metabolic diseases and existing therapeutic drugs, with the aim of providing a concise perspective on its potential applications in managing metabolic disorders.