Wilms' tumor 1-associating protein regulates G2/M transition through stabilization of cyclin A2 mRNA

WTAP targets SOX2 to inhibit trophoblast ferroptosis in the pathogenesis of preeclampsia via m6A-dependent ferroptosis regulation

BACKGROUND

Preeclampsia (PE) is associated with trophoblast damage, which may be caused by aberrant ferroptosis, an important process in placental development and function. The key component of N6-methyladenosine (m6A)-wilms tumor 1 associated protein (WTAP) has been reported to be involved in the migration and invasion of trophoblasts in the pathogenesis of PE. However, the connection between WTAP and ferroptosis in PE remained poorly understood. Accordingly, in order to explore potential treatments for PE, and understand how WTAP influences the trophoblasts' ferroptosis in PE, researchers conducted in vitro and in vivo experiments.

METHODS

Relevant molecular biology assays were conducted to investigate the effect of WTAP.

RESULTS

Here, we report that both m6A and WTAP levels were downregulated in placental tissue samples of 20 PE participants and the hypoxia model of trophoblast cell line HTR-8/SVneo, and down-regulation of WTAP promotes PE progression through m6A-dependent ferroptosis regulation. Stem cell transcriptional factor (SOX2) can specifically bind to the promoters of ferroptosis-related genes GPX4, SLC7A11, and FTH1 to regulate their expression in HTR-8/SVneo cells. In terms of molecular mechanisms, WTAP in trophoblast targeted the SOX2 gene. Through binding to its 3'-UTR m6A site, WTAP increased the stability of SOX2 mRNA. Moreover, animal studies demonstrated that WTAP could suppress ferroptosis and alleviate the symptoms of preeclampsia in the rat model of preeclampsia via SOX2.

CONCLUSION

WTAP mediates the m6A modification of SOX2 to regulate trophoblast ferroptosis in vitro and in vivo. Our findings point to a novel approach to treating PE and provide the groundwork for future research into this disease's RNA epigenetic regulation mechanisms.

FBLIM1 drives bile duct ligation-induced liver fibrosis by regulating the TGF-β signaling pathway through WTAP-mediated m6A modification

BACKGROUND

Liver fibrosis is one of the main severe pathological consequences of obstructive jaundice, and an effective treatment strategy is urgently needed. Filamin-binding LIM protein 1 (FBLIM1) is associated with fibrosis, however, there is no evidence to show the effect of FBLIM1 on obstructive jaundice.

METHODS

In our study, we investigated the function of FBLIM1 in bile duct ligation (BDL) rat models and human hepatic stellate cell (HSC) line LX-2.

RESULTS

Our findings confirmed that FBLIM1 was highly expressed in liver tissues of BDL rats. Liver histopathological injury, liver fibrosis, and inflammation response in BDL rats were attenuated by FBLIM1 knockdown. Moreover, FBLIM1 knockdown blocked the TGF-β signaling pathway in BDL rats. The results in TGF-β1-stimulation LX-2 cells further confirmed that FBLIM1 promoted LX-2 cell activation and fibrosis by regulating the TGF-β signaling pathway. FBLIM1 was further demonstrated to be modulated by Wilms's tumor 1-associating protein (WTAP), which was highly expressed in liver tissues of BDL rats. WTAP stabilized FBLIM1 mRNA and regulated FBLIM1 expression in an m6A-dependent manner.

CONCLUSION

Our findings provide evidence indicating that FBLIM1 promotes liver fibrosis via regulating the TGF-β signaling pathway through WTAP-mediated m6A modification. The WTAP/FBLIM1/TGF-β axis may be a potential therapeutic target against obstructive jaundice.

WTAP-induced m6A Methylation of Atoh8 Promotes Cell Proliferation and Fibrosis in Diabetic Nephropathy

Diabetic nephropathy (DN) is a common diabetic complication, which increases morbidity of end-stage renal failure. N6-methyladenosine (m6A) modification has been reported in association with multiple physiological processes, however, its role in diabetic nephropathy is still poorly understood. Here, we found that the levels of m6A modification were up-regulated in both high-glucose-cultured mouse mesangial cells and the renal tissues from db/db mice. The key methyltransferase WT1 associated protein (WTAP) was primarily responsible for the elevated m6A modification. Moreover, WTAP knockdown significantly inhibited the proliferation and fibrosis of mouse mesangial cells (MMCs). Mechanistically, using the combination analysis of MeRIP-Seq and RNA-Seq, we revealed that Atoh8 was a downstream target of WTAP-induced m6A modification. We first revealed that Atoh8 was lowly expressed in renal tissues of DN model mice and HG-induced mesangial cells. WTAP reduced Atoh8 expression by inhibiting Atoh8 mRNA stability. Overexpression of Atoh8 restrained the proliferation and fibrosis of mesangial cells. This study provides novel insights into the role of m6A modification in DN and suggests that WTAP and Atoh8 could serve as potential therapeutic targets for this condition.

WTAP-mediated m6A modification on BASP1 mRNA contributes to ferroptosis in AAA

BACKGROUND

Abdominal aortic aneurysm (AAA) is a common aneurysm that is often associated with atherosclerosis and can lead to artery rupture and death. Brain abundant membrane attached signal protein 1 (BASP1) is related to a variety of pathophysiological processes, but its role in AAA has not been reported.

METHODS

Real-time quantitative polymerase chain reaction (qRT-PCR) and western blot were used to detect the expressions of BASP1 and Wilms' tumor 1-associated protein (WTAP). Angiotensin-II (Ang-II) was employed for inducing AAA models in vitro to explore the effects and mechanism of BASP1 in AAA. Cell viability, apoptosis, oxidative stress level, and Fe2+ level were measured by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT), flow cytometry, and various kits, respectively. In terms of mechanism, the methylated RNA immunoprecipitation (MeRIP)-qPCR, the dual luciferase reporter assay, and the cytochrome experiments were utilized to evaluate the relationship between BASP1 and WTAP.

RESULTS

A highly expressed level of BASP1 was observed in aortic tissues of AAA patients and Ang-II could induce AAA models by treating vascular smooth muscle cells (VSMCs). In cellular function, BASP1 knockdown impaired AAA and ferroptosis resulted from Ang-II. Mechanically, WTAP mediated the N6-methyladenosine (m6A) modification and mRNA stability of BASP1. Meanwhile, WTAP was highly expressed in AAA tissues of patients and the effects of WTAP silence in AAA and ferroptosis were diminished by up-regulated BASP1.

CONCLUSION

WTAP promotes cell viability and inhibits apoptosis and ferroptosis resulted from Ang-II in VSMCs by mediating the m6A level of BASP1.

Dynamics and regulatory roles of RNA m6A methylation in unbalanced genomes

N6-methyladenosine (m6A) in eukaryotic RNA is an epigenetic modification that is critical for RNA metabolism, gene expression regulation, and the development of organisms. Aberrant expression of m6A components appears in a variety of human diseases. RNA m6A modification in Drosophila has proven to be involved in sex determination regulated by Sxl and may affect X chromosome expression through the MSL complex. The dosage-related effects under the condition of genomic imbalance (i.e. aneuploidy) are related to various epigenetic regulatory mechanisms. Here, we investigated the roles of RNA m6A modification in unbalanced genomes using aneuploid Drosophila. The results showed that the expression of m6A components changed significantly under genomic imbalance, and affected the abundance and genome-wide distribution of m6A, which may be related to the developmental abnormalities of aneuploids. The relationships between methylation status and classical dosage effect, dosage compensation, and inverse dosage effect were also studied. In addition, we demonstrated that RNA m6A methylation may affect dosage-dependent gene regulation through dosage-sensitive modifiers, alternative splicing, the MSL complex, and other processes. More interestingly, there seems to be a close relationship between MSL complex and RNA m6A modification. It is found that ectopically overexpressed MSL complex, especially the levels of H4K16Ac through MOF, could influence the expression levels of m6A modification and genomic imbalance may be involved in this interaction. We found that m6A could affect the levels of H4K16Ac through MOF, a component of the MSL complex, and that genomic imbalance may be involved in this interaction. Altogether, our work reveals the dynamic and regulatory role of RNA m6A modification in unbalanced genomes, and may shed new light on the mechanisms of aneuploidy-related developmental abnormalities and diseases.

Comprehensive Analysis of N6-Methyladenosine RNA Methylation Regulators in the Diagnosis and Subtype Classification of Rheumatoid Arthritis

m6A modification is the most abundant mRNA modifications and plays an integral role in various biological processes in eukaryotes. However, the role of m6A regulators in rheumatoid arthritis remains unknown. To determine the expression of m6A RNA methylation regulators in rheumatoid arthritis and their possible functional and prognostic value. In this study, we performed differential analysis in the comprehensive gene expression database GSE93272 dataset between non-rheumatoid arthritis patients and rheumatoid arthritis patients to obtain 15 important m6A regulators. A random forest model and lasso regression were used to screen the five most important m6A regulators to predict the risk of developing rheumatoid arthritis. After further validation using in vitro qPCR experiments, a nomogram model was developed based on the four most important m6A regulators (ELAVL1, WTAP, YTHDF1, and ALKBH5). Immuno-infiltration analysis and consensus clustering analysis were then performed. An analysis of the decision curve showed that the nomogram model could be beneficial to patients. According to selected important m6A regulators, patients with rheumatoid arthritis were classified into two m6A models (ClusterA and ClusterB) via consensus approach. Activated B cells, CD56dim natural killer cells, immature B cells, monocytes, natural killer T cells, and T lymphocytes were associated with ClusterA in immune infiltration analysis. Importantly, immune infiltration in patients with high ELAVL1 expression was strikingly similar to ClusterA. m6A regulators play a non-negligible role in the development of rheumatoid arthritis. A study of m6A patterns may provide future therapeutic options for rheumatoid arthritis.

Marrow mesenchymal stem cell mediates diabetic nephropathy progression via modulation of Smad2/3/WTAP/m6A/ENO1 axis

Diabetic nephropathy (DN) is one of the common microvascular complications in diabetic patients. Marrow mesenchymal stem cells (MSCs) have attracted attention in DN therapy but the underlying mechanism remains unclear. Here, we show that MSC administration alleviates high glucose (HG)-induced human kidney tubular epithelial cell (HK-2 cell) injury and ameliorates renal injury in DN mice. We identify that Smad2/3 is responsible for MSCs-regulated DN progression. The activity of Smad2/3 was predominantly upregulated in HG-induced HK-2 cell and DN mice and suppressed with MSC administration. Activation of Smad2/3 via transforming growth factor-β1 (TGF-β1) administration abrogates the protective effect of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Smad2/3 has been reported to interact with methyltransferase of N6-methyladenosine (m6A) complex and we found a methyltransferase, Wilms' tumor 1-associating protein (WTAP), is involved in MSCs-Smad2/3-regulated DN development. Moreover, WTAP overexpression abrogates the improvement of MSCs on HG-induced HK-2 cell injury and renal injury of DN mice. Subsequently, α-enolase (ENO1) is the downstream target of WTAP-mediated m6A modification and contributes to the MSCs-mediated regulation. Collectively, these findings reveal a molecular mechanism in DN progression and indicate that Smad2/3/WTAP/ENO1 may present a target for MSCs-mediated DN therapy.

Regulatory role of m6A epitranscriptomic modifications in normal development and congenital malformations during embryogenesis

The discovery of N6-methyladenosine (m6A) methylation and its role in translation has led to the emergence of a new field of research. Despite accumulating evidence suggesting that m6A methylation is essential for the pathogenesis of cancers and aging diseases by influencing RNA stability, localization, transformation, and translation efficiency, its role in normal and abnormal embryonic development remains unclear. An increasing number of studies are addressing the development of the nervous and gonadal systems during embryonic development, but only few are assessing that of the immune, hematopoietic, urinary, and respiratory systems. Additionally, these studies are limited by the requirement for reliable embryonic animal models and the difficulty in collecting tissue samples of fetuses during development. Multiple studies on the function of m6A methylation have used suitable cell lines to mimic the complex biological processes of fetal development or the early postnatal phase; hence, the research is still in the primary stage. Herein, we discuss current advances in the extensive biological functions of m6A methylation in the development and maldevelopment of embryos/fetuses and conclude that m6A modification occurs extensively during fetal development. Aberrant expression of m6A regulators is probably correlated with single or multiple defects in organogenesis during the intrauterine life. This comprehensive review will enhance our understanding of the pivotal role of m6A modifications involved in fetal development and examine future research directions in embryogenesis.

WTAP gene variants and susceptibility to ovarian endometriosis in a Chinese population

Background: Endometriosis is a common chronic gynecologic disorder with a significant negative impact on women's health. Wilms tumor 1-associated protein (WTAP) is a vital component of the RNA methyltransferase complex for N6-methyladenosine modification and plays a critical role in various human diseases. However, whether single nucleotide polymorphisms (SNPs) of the WTAP gene predispose to endometriosis risk remains to be investigated. Methods: We genotyped three WTAP polymorphisms in 473 ovarian endometriosis patients and 459 control participants using the Agena Bioscience MassArray iPLEX platform. The logistic regression models were utilized to assess the associations between WTAP SNPs and the risk of ovarian endometriosis. Results: In the single-locus analyses, we found that the rs1853259 G variant genotypes significantly increased, while the rs7766006 T variant genotypes significantly decreased the association with ovarian endometriosis risk. Combined analysis indicated that individuals with two unfavorable genotypes showed significantly higher ovarian endometriosis risk (adjusted OR = 1.71 [1.23-2.37], p = 0.001) than those with zero risk genotypes. In the stratified analysis, the risk effect of the rs1853259 AG/GG and rs7766006 GG genotypes was evident in subgroups of age ≤30, gravidity≤1, parity≤1, rASRM stage I, and the rs7766006 GG genotype was associated with worse risk (adjusted OR = 1.64 [1.08-2.48], p = 0.021) in the patients with rASRM stage II + III + IV. The haplotype analysis indicated that individuals with GGG haplotypes had a higher risk of ovarian endometriosis than wild-type AGG haplotype carriers. Moreover, false positive report probability and Bayesian false discovery probability analysis validated the reliability of the significant results. The quantitative expression trait loci analysis revealed that rs1853259 and rs7766006 were correlated with the expression levels of WTAP. Conclusion: Our findings demonstrated that WTAP polymorphisms were associated with susceptibility to ovarian endometriosis among Chinese women.

N6-methyladenosine (m6A) methyltransferase WTAP-mediated miR-92b-5p accelerates osteoarthritis progression

The study was design to investigate the functional roles of Wilms tumor 1-associated protein (WTAP), an enzyme catalyzes m6A modification, in the pathogenesis of osteoarthritis (OA) and further elucidate its possible regulatory mechanism. Herein, we discovered that WTAP was outstandingly upregulated in chondrocyte stimulated with Lipopolysaccharide (LPS) and cartilage tissue of patients with OA. Functional studies have demonstrated that WTAP knockdown enhances proliferation ability, suppresses apoptosis, and reduces extracellular matrix (ECM) degradation in an LPS-induced OA chondrocyte injury model and ameliorates cartilage damage in a destabilizing the medial meniscus (DMM)-induced OA mice model. Conversely, overexpression of WTAP contributes to the opposite effects. Mechanistically, our data has demonstrated that m6A modification mediated by WTAP promotes the maturation of pri-miR-92b to miR-92b-5p, thereby enhancing the targeted inhibitory function of miR-92b-5p on TIMP4. Furthermore, we have discovered that WTAP can directly facilitate the degradation of TIMP4 mRNAs in a YTHDF2-dependent manner. In a nutshell, our findings suggested that WTAP knockdown alleviated OA progression by modulating the miR-92b-5p/TIMP4 axis in an m6A-dependent manner. Our study disclosed that WTAP-mediated m6A modification displayed a crucial role in OA development and suggested that targeting WTAP could be a promising preventive and therapeutic target for patients with OA. Video Abstract.

Epitranscriptional Regulation: From the Perspectives of Cardiovascular Bioengineering

The central dogma of gene expression involves DNA transcription to RNA and RNA translation into protein. As key intermediaries and modifiers, RNAs undergo various forms of modifications such as methylation, pseudouridylation, deamination, and hydroxylation. These modifications, termed epitranscriptional regulations, lead to functional changes in RNAs. Recent studies have demonstrated crucial roles for RNA modifications in gene translation, DNA damage response, and cell fate regulation. Epitranscriptional modifications play an essential role in development, mechanosensing, atherogenesis, and regeneration in the cardiovascular (CV) system, and their elucidation is critically important to understanding the molecular mechanisms underlying CV physiology and pathophysiology. This review aims at providing biomedical engineers with an overview of the epitranscriptome landscape, related key concepts, recent findings in epitranscriptional regulations, and tools for epitranscriptome analysis. The potential applications of this important field in biomedical engineering research are discussed.

The Emerging, Multifaceted Role of WTAP in Cancer and Cancer Therapeutics

Cancer is a grave and persistent illness, with the rates of both its occurrence and death toll increasing at an alarming pace. N6-methyladenosine (m⁶A), the most prevalent mRNA modification in eukaryotic organisms, is catalyzed by methyltransferases and has a significant impact on various aspects of cancer progression. WT1-associated protein (WTAP) is a crucial component of the m⁶A methyltransferase complex, catalyzing m⁶A methylation on RNA. It has been demonstrated to participate in numerous cellular pathophysiological processes, including X chromosome inactivation, cell proliferation, cell cycle regulation, and alternative splicing. A better understanding of the role of WTAP in cancer may render it a reliable factor for early diagnosis and prognosis, as well as a key therapeutic target for cancer treatment. It has been found that WTAP is closely related to tumor cell cycle regulation, metabolic regulation, autophagy, tumor immunity, ferroptosis, epithelial mesenchymal transformation (EMT), and drug resistance. In this review, we will focus on the latest advances in the biological functions of WTAP in cancer, and explore the prospects of its application in clinical diagnosis and therapy.

Role of N6-methyladenosine modification in central nervous system diseases and related therapeutic agents

N6-methyladenosine (m6A) is a ubiquitous mRNA modification in eukaryotes. m6A occurs through the action of methyltransferases, demethylases, and methylation-binding proteins. m6A methylation of RNA is associated with various neurological disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), depression, cerebral apoplexy, brain injury, epilepsy, cerebral arteriovenous malformations, and glioma. Furthermore, recent studies report that m6A-related drugs have attracted considerable concerns in the therapeutic areas of neurological disorders. Here, we mainly summarized the role of m6A modification in neurological diseases and the therapeutic potential of m6A-related drugs. The aim of this review is expected to be useful to systematically assess m6A as a new potential biomarker and develop innovative modulators of m6A for the amelioration and treatment of neurological disorders.

WTAP regulates stem cells via TRAF6 to maintain planarian homeostasis and regeneration

WTAP, a highly conserved Wilms' tumor 1 interacting protein, is involved in a variety of biological processes. However, functional studies of WTAP in planarians have not been reported. In this study, we examined the spatiotemporal expression pattern of planarian DjWTAP and investigated its functions in planarians regeneration and homeostasis. Knocking-down DjWTAP resulted in severe morphological defects leading to lethality within 20 days. Silencing DjWTAP promoted the proliferation of PiwiA⁺ cells but impaired the lineage differentiation of epidermal, neural, digestive, and excretory cell types, suggesting a critical role for DjWTAP in stem cell self-renewal and differentiation in planarian. To further investigate the mechanisms underlying the defective differentiation, RNA-seq was employed to determine the transcriptomic alterations upon DjWTAP RNA interference. Histone 4 (H4), Histone-lysine N-methyltransferase-SETMAR like, and TNF receptor-associated factor 6 (TRAF6), were significantly upregulated in response to DjWTAP RNAi. Knocking-down TRAF6 largely rescued the defective tissue homeostasis and regeneration resulted from DjWTAP knockdown in planarians, suggesting that DjWTAP maintains planarian regeneration and homeostasis via TRAF6.

Circular RNA circDLG1 contributes to HCC progression by regulating the miR-141-3p/WTAP axis

This study aims to explore novel and reliable biomarkers for predicting hepatocellular carcinoma (HCC) prognosis. Circular RNAs (circRNAs) were determined by analysis of human circRNA arrays and quantitative reverse transcription polymerase reactions. To test for an interaction between circDLG1, we used luciferase reporter assays, RNA immunoprecipitation, and fluorescence in situ hybridization assays that were employed to test the interaction between circDLG1, miR-141-3p, and WTAP. q-RT-PCR and western blot were used to evaluate the target regulation of miR-141-3p and WTAP. shRNA-mediated knockdown of circDLG1, proliferation, migration, and invasion experiment of metastasis were used to evaluate the function of circDLG. CircDLG1 rather than lining DLG1 was upregulated in HCC tissues, from HCC patients as well as HCC cell lines compared to normal controls. circDLG1 high expression in HCC patients was correlated with shorter overall survival. Knockdown of circDLG1 and miR-141-3p mimic could inhibit the tumorigenesis of HCC cells in vivo and in vitro. Importantly, we demonstrated that circDLG1 could act as a sponge of miR-141-3p to regulate the expression of WTAP, and further suppress the tumorigenesis of HCC cells. Our study reveals that circDLG1 can serve as a novel potential circulating biomarker for the detection of HCC. circDLG1 participates in the progression of HCC cells by sponging miR-141-3p with WTAP, providing new insight into the treatment of HCC.

Epitranscriptome marks detection and localization of RNA modifying proteins in mammalian ovarian follicles

BACKGROUND

Most of the resources that support the early development of the embryo are stored in the oocyte. Clearing of maternal resources and activation of the embryonic genome to produce its own mRNA transcripts marks the maternal-to-embryo transition. Dependence on stored mRNA can last from a few hours to several days, depending on animal species. The mechanisms regulating stabilization and recruitment of stored maternal transcripts have not yet been described in full detail but are known to involve reversible polyadenylation and modulation of 3'UTR-mediated elements. RNA epigenetic modifications, new players in this field, have an important role in RNA regulation and stabilization.

RESULTS

The objectives of this study were first to determine if some of post-transcriptional methylation of stored mRNA is greater in oocytes than in somatic cells. We found that m⁶A, known to be the most prevalent and involved in various aspects of RNA metabolism and physiological functions, is particularly abundant in porcine oocyte mRNA compared to liver used as a somatic tissue reference. The second objective was to compare the epitranscriptome machinery, such as methyltransferases ("writers"), binding proteins ("readers") and demethylases ("erasers") catalyzing the different process, in follicles and oocytes of different mammalian species by immunofluorescence and confocal microscopy. The expression and localization patterns of these proteins differ between mice, pigs and cows ovaries and oocytes. m⁵C-associated proteins were generally less abundant. In contrast, m⁶A-associated proteins were expressed strongly during the early and late stages of folliculogenesis. Transzonal projections were found to contain more granules bearing the m⁵C mark in mice but both m⁵C and m⁶A methylation marks in association with mature oocytes of pigs and cows. Eraser proteins showed the greatest interspecies diversity in terms of distribution in the germinal tissues.

CONCLUSIONS

So far, few studies have looked at the oocyte and ovarian epitranscriptomic profile. Our findings indicate that a hitherto unrecognized species-specific layer of transcript regulation occurs at the RNA level and might be consequential during the oocyte transcriptional silencing period.

HIF1α-mediated transactivation of WTAP promotes AML cell proliferation via m6A-dependent stabilization of KDM4B mRNA

Hypoxia inducible factor 1α (HIF1α) is abnormally overexpressed in t(8;21) acute myeloid leukemia (AML) and functions as an oncogene through transactivating DNA methyltransferase 3 alpha leading to DNA hypermethylation. However, it remains unclear whether HIF1α influences RNA N⁶-methyladenosine (m⁶A) methyltransferases. Here, we show that HIF1α promotes the expression of Wilms tumor 1-associated protein (WTAP), a main component of the m⁶A methyltransferase complex, markedly alters the transcriptome-wide m⁶A distribution and enhances cell proliferation in t(8;21) AML. In agreement with this, WTAP is overexpressed and predicts poor prognosis in t(8;21) AML patients. Moreover, WTAP knockdown inhibits growth, and induces apoptosis and differentiation of leukemia cells. Mechanistically, HIF1α transactivates WTAP gene expression by directly binding to the hypoxia-response element of its promoter region. Pharmacological or genetic intervention in the HIF1α-WTAP axis results in the reduction of m⁶A level on lysine demethylase 4B (KDM4B) transcripts and increased its degradation, correlated with lower expression of KDM4B and higher trimethylation levels of histone H3 on lysine 9. KDM4B knockdown inhibits leukemia cell growth in vitro and in mice. Thus, HIF1α-mediated WTAP high expression enhances the malignant behavior of leukemia cells and drives a crosstalk between m⁶A RNA methylation and histone methylation through monitoring m⁶A-dependant KDM4B translation.

The essential role of N6-methyladenosine RNA methylation in complex eye diseases

There are many complex eye diseases which are the leading causes of blindness, however, the pathogenesis of the complex eye diseases is not fully understood, especially the underlying molecular mechanisms of N6-methyladenosine (m6A) RNA methylation in the eye diseases have not been extensive clarified. Our review summarizes the latest advances in the studies of m6A modification in the pathogenesis of the complex eye diseases, including cornea disease, cataract, diabetic retinopathy, age-related macular degeneration, proliferative vitreoretinopathy, Graves' disease, uveal melanoma, retinoblastoma, and traumatic optic neuropathy. We further discuss the possibility of developing m6A modification signatures as biomarkers for the diagnosis of the eye diseases, as well as potential therapeutic approaches.

Wilms Tumor 1-Associated Protein Expression Is Linked to a T-Cell-Inflamed Phenotype in Pancreatic Cancer

BACKGROUND

The molecular driving forces of anti-tumor immunity in pancreatic ductal adenocarcinoma (PDAC) remain unclear, which causing great difficulty in identifying an appropriate treatment strategy.

AIMS

This study aims to explore the associations between expression of Wilms tumor 1-associated protein (WTAP) and effector T-cell infiltration in PDAC.

METHODS

In this study, we explored the association between WTAP expression and infiltration level of CD8+ T cells in PDAC. 178 PDAC samples were selected from The Cancer Genome Atlas (TCGA) database. The associations between diverse immune-cell infiltration, Tumor Mutation Burden (TMB), immune checkpoints, and WTAP expression were performed via R software. Transcriptional hallmarks of anti-tumor immunity and known T-cell-inflamed signature of PDAC were both selected to explore the relevance to WTAP expression. Potential immune checkpoint blockade (ICB) response to different WTAP expression was predicted with tumor immune dysfunction and exclusion (TIDE) algorithm.

RESULTS

WTAP was closely linked to CD8+ T-cell infiltration (r ≥ 0.5, P value < 0.05) and did not show notable association with TMB in PDAC. WTAP positively linked to T-cell-inflamed gene expression profiles (GEP) (IL2RB, IL2RA, ZAP70, ITK, CD3E, CD38, CD27, CD276, CD8A, CMKLR1, CXCR6, HLA-DQA1, HLA-DRB1, HLA-E, NKG7, and STAT1), cytolytic activity (GZMA and PRF1), various immune checkpoints (IDO1, CD274, HAVCR2, PDCD1, CTLA4, LAG3, and PDCD1LG2) and 4-chemokine signature (CCL4, CCL5, CXCL9, and CXCL10). Besides, increased expression of WTAP was related to a higher TIDE score.

CONCLUSIONS

WTAP marks PDAC tumors with an active anti-tumor phenotype and might help the identification of PDAC patients who might benefit from immunotherapies.

FASN multi-omic characterization reveals metabolic heterogeneity in pancreatic and prostate adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) and prostate cancer (PCa) are among the most prevalent malignant tumors worldwide. There is now a comprehensive understanding of metabolic reprogramming as a hallmark of cancer. Fatty acid synthase (FASN) is a key regulator of the lipid metabolic network, providing energy to favor tumor proliferation and development. Whereas the biological role of FASN is known, its response and sensitivity to inhibition have not yet been fully established in these two cancer settings.

METHODS

To evaluate the association between FASN expression, methylation, prognosis, and mutational profile in PDAC and PCa, we interrogated public databases and surveyed online platforms using TCGA data. The STRING database was used to investigate FASN interactors, and the Gene Set Enrichment Analysis platform Reactome database was used to perform an enrichment analysis using data from RNA sequencing public databases of PDAC and PCa. In vitro models using PDAC and PCa cell lines were used to corroborate the expression of FASN, as shown by Western blot, and the effects of FASN inhibition on cell proliferation/cell cycle progression and mitochondrial respiration were investigated with MTT, colony formation assay, cell cycle analysis and MitoStress Test.

RESULTS

The expression of FASN was not modulated in PDAC compared to normal pancreatic tissues, while it was overexpressed in PCa, which also displayed a different level of promoter methylation. Based on tumor grade, FASN expression decreased in advanced stages of PDAC, but increased in PCa. A low incidence of FASN mutations was found for both tumors. FASN was overexpressed in PCa, despite not reaching statistical significance, and was associated with a worse prognosis than in PDAC. The biological role of FASN interactors correlated with lipid metabolism, and GSEA indicated that lipid-mediated mitochondrial respiration was enriched in PCa. Following validation of FASN overexpression in PCa compared to PDAC in vitro, we tested TVB-2640 as a FASN inhibitor. PCa proliferation arrest was modulated by FASN inhibition in a dose- and time-dependent manner, whereas PDAC proliferation was not altered. In line with this finding, mitochondrial respiration was found to be more affected in PCa than in PDAC. FASN inhibition interfered with metabolic signaling causing lipid accumulation and affecting cell viability with an impact on the replicative processes.

CONCLUSIONS

FASN exhibited differential expression patterns in PDAC and PCa, suggesting a different evolution during cancer progression. This was corroborated by the fact that both tumors responded differently to FASN inhibition in terms of proliferative potential and mitochondrial respiration, indicating that its use should reflect context specificity.

WTAP regulates postnatal development of brown adipose tissue by stabilizing METTL3 in mice

Brown adipocyte maturation during postnatal development is essential for brown adipose tissue (BAT) to protect animals against cold. Impaired maturation of brown adipocytes leads to cold intolerance. However, the molecular mechanisms that determine the maturation of brown adipocytes during postnatal development are not fully understood. Here, we identify Wilms' tumor 1-associating protein (WTAP) as an essential regulator in the postnatal development and maturation of BAT. BAT-specific knockout of Wtap (Wtap-BKO) severely impairs maturation of BAT in vivo by decreasing the expression of BAT-selective genes, leading to the whitening of interscapular BAT (iBAT). Single nucleus RNA-sequencing analysis shows the dynamic changes of cell heterogeneity in iBAT of Wtap-BKO mice. Adult mice with WTAP deficiency in BAT display hypothermic and succumb to acute cold challenge. Mechanistically, WTAP deficiency decreases m6A mRNA modification by reducing the protein stability of METTL3. BAT-specific overexpression of Mettl3 partially rescues the phenotypes observed in Wtap-BKO mice. These data demonstrate that WTAP/METTL3 plays an essential role in iBAT postnatal development and thermogenesis.

WTAP dysregulation-mediated HMGN3-m6A modification inhibited trophoblast invasion in early-onset preeclampsia

Early-onset preeclampsia (ePE) originates from abnormal implantation and placentation that involves trophoblast invasion, but its pathophysiology is not entirely understood. N6-methyladenosine (m6A) regulators mediate the progression of various cancers. The invasiveness of trophoblast cells is similar to that of tumor cells. However, little is known regarding the potential role of m6A modification in ePE and the underlying mechanism. This study aimed to explore the m6A level in placental tissue samples collected from ePE patients and to investigate whether m6A modification was an essential part of PE pathogenesis. The m6A level in placental tissue samples of 80 PE participants was examined. MeRIP-microarray, RNA-Seq, luciferase reporter assay, and RNA immunoprecipitation chip (RIP) assay were performed. The m6A level in the ePE group was significantly reduced compared with the control group. Wilms' tumor 1-associating protein (WTAP) regulated trophoblast cell migration and invasion. Mechanistically, the high mobility group nucleosomal binding domain 3 (HMGN3) gene was a target gene of WTAP in trophoblast (p < .05). WTAP enhanced the stability of HMGN3 mRNA through binding with its 3'-UTR m6A site(+485A, +522A). HMGN3 was recognized by m6A recognition protein insulin-like growth factor 2 mRNA-binding protein 1 (IGF2BP1), which was inhibited when knocking down WTAP. Both m6A and WTAP levels were downregulated in ePE. The m6A modification mediated by WTAP/IGF2BP1/HMGN3 axis might contribute to abnormal trophoblast invasion. Our work provided a foundation for further exploration of RNA epigenetic regulatory patterns in ePE, and indicated a new treatment strategy for ePE.

N6-methyladenosine (m6A) RNA methylation mediated by methyltransferase complex subunit WTAP regulates amelogenesis

N6-methyladenosine (m6A) RNA methylation, one of the most widespread posttranscriptional modifications in eukaryotes, plays crucial roles in various developmental processes. The m6A modification process is catalyzed by a methyltransferase complex that includes Wilms tumor 1-associated protein (WTAP) as a key component. Whether the development of dental enamel is regulated by m6A RNA methylation in mammals remains unclear. Here, we reveal that WTAP is widely expressed from the early stage of tooth development. Specific inactivation of Wtap in mouse enamel epithelium by the Cre/loxp system leads to serious developmental defects in amelogenesis. In Wtap conditional KO mice, we determined that the differentiation of enamel epithelial cells into mature ameloblasts at the early stages of enamel development is affected. Mechanistically, loss of Wtap inhibits the expression of Sonic hedgehog (SHH), which plays an important role in the generation of ameloblasts from stem cells. Together, our findings provide new insights into the functional role of WTAP-mediated m6A methylation in amelogenesis in mammals.

Comprehensive Analysis Revealed the Potential Roles of N6-Methyladenosine (m6A) Mediating E. coli F18 Susceptibility in IPEC-J2 Cells

Post-weaning diarrhea caused by enterotoxigenic Escherichia coli F18 (E. coli F18) causes significant economic losses for pig producers. N6-methyladenosine (m6A) is a highly abundant epitranscriptomic marker that has been found to be involved in regulating the resistance of host cells to pathogenic infection, but its potential role in E. coli F18-exposed intestinal porcine epithelial cells (IPEC-J2) remains undetermined. Here, we demonstrated that m6A and its regulators modulate E. coli F18 susceptibility. Briefly, we revealed that the Wilms’ tumor 1-associating protein (WTAP) expressions were markedly elevated in IPEC-J2 cells upon E. coli F18 exposure. WTAP are required for the regulation of E. coli F18 adhesion in IPEC-J2 cells. Additionally, WTAP knockdown significantly suppressed m6A level at N-acetyllactosaminide beta-1,6-N-acetylglucosaminyl-transferase (GCNT2) 3′UTR, resulting in the enhancement of TH N6-methyladenosine RNA binding protein 2 (YTHDF2)-mediated GCNT2 mRNA stability. Subsequently, the altered GCNT2 expressions could inhibit the glycosphingolipid biosynthesis, thus improving resistance to E. coli F18 infection in IPEC-J2. Collectively, our analyses highlighted the mechanism behind the m6A-mediated management of E. coli F18 susceptibility, which will aid in the development of novel approaches that protect against bacterial diarrhea in piglets.

The RNA m6A writer WTAP in diseases: structure, roles, and mechanisms

N6-methyladenosine (m⁶A) is a widely investigated RNA modification in studies on the "epigenetic regulation" of mRNAs that is ubiquitously present in eukaryotes. Abnormal changes in m⁶A levels are closely related to the regulation of RNA metabolism, heat shock stress, tumor occurrence, and development. m⁶A modifications are catalyzed by the m⁶A writer complex, which contains RNA methyltransferase-like 3 (METTL3), methyltransferase-like 14 (METTL14), Wilms tumor 1-associated protein (WTAP), and other proteins with methyltransferase (MTase) capability, such as RNA-binding motif protein 15 (RBM15), KIAA1429 and zinc finger CCCH-type containing 13 (ZC3H13). Although METTL3 is the main catalytic subunit, WTAP is a regulatory subunit whose function is to recruit the m⁶A methyltransferase complex to the target mRNA. Specifically, WTAP is required for the accumulation of METTL3 and METTL14 in nuclear speckles. In this paper, we briefly introduce the molecular mechanism of m⁶A modification. Then, we focus on WTAP, a component of the m⁶A methyltransferase complex, and introduce its structure, localization, and physiological functions. Finally, we describe its roles and mechanisms in cancer.

A potential biomarker of esophageal squamous cell carcinoma WTAP promotes the proliferation and migration of ESCC

This study focuses on the function of WTAP in esophageal squamous cell carcinoma (ESCC) samples and cell lines. The results showed that WTAP expression in ESCC tissues was significantly upregulated in 78.1% (57 of 73) of the ESCC tissues at the protein level compared with adjacent non-cancerous tissues via immunohistochemical staining. The WTAP protein expression level was positively correlated with the lymph node metastasis and TNM stage, and patients with higher WTAP protein expression level exhibited a shorter overall survival interval. Knocking down WTAP significantly reduced cell proliferation and migration but promoted cell apoptosis of TE-1and KYSE150 cells. Moreover, WTAP inhibition reduced the expression of ki67 and Snail related to cell proliferation and migration but increased the expression of Bax and Caspase-3 which were involved in cell apoptosis. In conclusion, our results suggest that the WTAP, a potential biomarker of ESCC, maybe play an important role in ESCC-genesis through regulating expression of genes related to cell proliferation, migration and apoptosis.

Analysis of N6-Methyladenosine RNA Methylation Regulators in Diagnosis and Distinct Molecular Subtypes of Ankylosing Spondylitis

The most frequent internal modification in eukaryotic mRNA is N6-methyladenosine (m6A). However, what we know about the m6A regulators in Ankylosing spondylitis (AS) is still limited. In our study, eight distinct m6A regulators were selected utilizing Differentially Expressed Gene (DEG) analysis of the Gene Expression Omnibus GSE73754 dataset for making comparisons between AS (Ankylosing spondylitis) and non-AS patients. The random forest model and the nomogram model were used to screen the eight candidate m6A regulators and evaluate their prediction accuracy for the occurrence of AS. Furthermore, based on the selected m6A regulators, the AS patients were divided into two subgroups, and we applied principal component analysis algorithms to calculate their m6A score and evaluate the m6A patterns. Our findings revealed that patients in cluster A were linked to activated CD4 T cell immunity and activated CD8 T cell immunity. With its major contributions in the area of immunology, our research in m6A patterns may benefit the future diagnosis and treatment strategies of AS.

Comprehensive analysis about prognostic and immunological role of WTAP in pan-cancer

Background: Wilms tumor 1-associated protein (WTAP) plays a critical role in ribonucleic acid (RNA) methylation of N6 adenosine (m6A) modification, which is closely related with varieties of biological process. However, the role of WTAP in cancers remains to be determined. This study is designed to demonstrate the prognostic landscape of WTAP in pan-cancer and explore the relationship between WTAP expression and immune infiltration. Methods: Here, we investigated the expression level and prognostic role of WTAP in pan-cancer using multiple databases, including PrognoScan, GEPIA, and Kaplan-Meier Plotter. Then, applying the GEPIA and TIMER databases, we illustrated the correlations between WTAP expression and immune infiltration in tumors, especially liver hepatocellular carcinoma (LIHC), and esophageal carcinoma (ESCA). Results: WTAP had significant higher expression levels in tumor tissues of ESCA, LIHC, etc., while lower expression levels in those of bladder urothelial carcinoma (BLCA), breast invasive carcinoma (BRCA), etc. And WTAP demonstrated multifaceted prognostic value in cancers. Of our interests, WTAP exerted a harmful effect on LIHC patient for overall survival (OS) and progression free survival (PFS). WTAP expression also significantly associated with the infiltration levels of B cells, CD8+ T cells, CD4+ T cells, macrophages, neutrophils, and dendritic cells (DC) in LIHC but not ESCA. Furthermore, combined analysis about WTAP expression level and immune cell specific gene markers implied WTAP correlates with regulatory cells (T reg) infiltration in LIHC and ESCA. Conclusion: The m6A regulator WTAP can serve as a prognostic biomarker for certain tumor types in pan-cancer and potentially result from immune cell infiltration.

The role of RNA modification in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly mortal type of primary liver cancer. Abnormal epigenetic modifications are present in HCC, and RNA modification is dynamic and reversible and is a key post-transcriptional regulator. With the in-depth study of post-transcriptional modifications, RNA modifications are aberrantly expressed in human cancers. Moreover, the regulators of RNA modifications can be used as potential targets for cancer therapy. In RNA modifications, N6-methyladenosine (m6A), N7-methylguanosine (m7G), and 5-methylcytosine (m5C) and their regulators have important regulatory roles in HCC progression and represent potential novel biomarkers for the confirmation of diagnosis and treatment of HCC. This review focuses on RNA modifications in HCC and the roles and mechanisms of m6A, m7G, m5C, N1-methyladenosine (m1A), N3-methylcytosine (m3C), and pseudouridine (ψ) on its development and maintenance. The potential therapeutic strategies of RNA modifications are elaborated for HCC.

Role of WTAP in Cancer: From Mechanisms to the Therapeutic Potential

Wilms' tumor 1-associating protein (WTAP) is required for N⁶-methyladenosine (m⁶A) RNA methylation modifications, which regulate biological processes such as RNA splicing, cell proliferation, cell cycle, and embryonic development. m⁶A is the predominant form of mRNA modification in eukaryotes. WTAP exerts m⁶A modification by binding to methyltransferase-like 3 (METTL3) in the nucleus to form the METTL3-methyltransferase-like 14 (METTL14)-WTAP (MMW) complex, a core component of the methyltransferase complex (MTC), and localizing to the nuclear patches. Studies have demonstrated that WTAP plays a critical role in various cancers, both dependent and independent of its role in m⁶A modification of methyltransferases. Here, we describe the recent findings on the structural features of WTAP, the mechanisms by which WTAP regulates the biological functions, and the molecular mechanisms of its functions in various cancers. By summarizing the latest WTAP research, we expect to provide new directions and insights for oncology research and discover new targets for cancer treatment.

RNA splicing: a dual-edged sword for hepatocellular carcinoma

RNA splicing is the fundamental process that brings diversity at the transcriptome and proteome levels. The spliceosome complex regulates minor and major processes of RNA splicing. Aberrant regulation is often associated with different diseases, including diabetes, stroke, hypertension, and cancer. In the majority of cancers, dysregulated alternative RNA splicing (ARS) events directly affect tumor progression, invasiveness, and often lead to poor survival of the patients. Alike the rest of the gastrointestinal malignancies, in hepatocellular carcinoma (HCC), which alone contributes to ~ 75% of the liver cancers, a large number of ARS events have been observed, including intron retention, exon skipping, presence of alternative 3'-splice site (3'SS), and alternative 5'-splice site (5'SS). These events are reported in spliceosome and non-spliceosome complexes genes. Molecules such as MCL1, Bcl-X, and BCL2 in different isoforms can behave as anti-apoptotic or pro-apoptotic, making the spliceosome complex a dual-edged sword. The anti-apoptotic isoforms of such molecules bring in resistance to chemotherapy or cornerstone drugs. However, in contrast, multiple malignant tumors, including HCC that target the pro-apoptotic favoring isoforms/variants favor apoptotic induction and make chemotherapy effective. Herein, we discuss different splicing events, aberrations, and antisense oligonucleotides (ASOs) in modulating RNA splicing in HCC tumorigenesis with a possible therapeutic outcome.

Deficiency of WTAP in hepatocytes induces lipoatrophy and non-alcoholic steatohepatitis (NASH)

Ectopic lipid accumulation and inflammation are the essential signs of NASH. However, the molecular mechanisms of ectopic lipid accumulation and inflammation during NASH progression are not fully understood. Here we reported that hepatic Wilms' tumor 1-associating protein (WTAP) is a key integrative regulator of ectopic lipid accumulation and inflammation during NASH progression. Hepatic deletion of Wtap leads to NASH due to the increased lipolysis in white adipose tissue, enhanced hepatic free fatty acids uptake and induced inflammation, all of which are mediated by IGFBP1, CD36 and cytochemokines such as CCL2, respectively. WTAP binds to specific DNA motifs which are enriched in the promoters and suppresses gene expression (e.g., Igfbp1, Cd36 and Ccl2) with the involvement of HDAC1. In NASH, WTAP is tranlocated from nucleus to cytosol, which is related to CDK9-mediated phosphorylation. These data uncover a mechanism by which hepatic WTAP regulates ectopic lipid accumulation and inflammation during NASH progression.

Ectopic lipid accumulation and inflammation are the essential signs of NASH. Here, the authors show that hepatic WTAP is a key integrative repressor of ectopic lipid accumulation and inflammation during NASH progression, and hepatic deletion of Wtap promotes both of them, leading to NASH

WTAP Is Correlated With Unfavorable Prognosis, Tumor Cell Proliferation, and Immune Infiltration in Hepatocellular Carcinoma

WTAP is involved in various pathological and physiological processes, but its function in hepatocellular carcinoma (HCC) remains elusive. In this study, we investigated the role of WTAP in HCC. Firstly, the mRNA and protein of WTAP were expressed highly in HCC tissue, which reflected clinicopathological characteristics of HCC patients. Then, an interactive analysis of genetic profiles and Kaplan–Meier curves was performed to show that WTAP was an independent predictor of survival of HCC patients. Meanwhile, genes co-expressed with WTAP, potential protein–protein interactions, related signaling pathways, and immune cell infiltration were identified. It was found that high WTAP expression correlated with enhanced interactions between cytokines and their receptors, cell cycle, and chemokine signaling pathways, as well as increased immune cell infiltration. At last, WTAP knockdown experiments in vitro indicate that the WTAP silencing inhibited HCC proliferation and aggressiveness. We conclude that WTAP may be a novel biomarker for prognosis and a therapeutic target for HCC.

m6A Methylases Regulate Myoblast Proliferation, Apoptosis and Differentiation

Simple Summary

N⁶-methyladenosine (m⁶A) is the most prevalent methylation modification in eukaryotic mRNA, and it plays an important role in regulating gene expression. Previous studies found that m⁶A methylation plays a role in mammalian skeletal muscle development. Skeletal muscle is an important factor that regulates livestock muscle quality and maintains metabolic homeostasis, and skeletal myogenesis is regulated by a series of transcription factors. However, the role of m⁶A in bovine skeletal myogenesis is unclear. In this study, we examined the expression patterns of the m⁶A methylase genes METTL3, METTL14, WTAP, FTO and ALKBH5 in bovine skeletal muscle tissue and during myogenesis in myoblasts. Furthermore, we used bovine skeletal muscle myoblasts as the object of study to discover the regulatory role of these genes in the process of skeletal myogenesis in vitro. Our findings indicate that these five m⁶A methylases have pronounced and diverse functions in regulating bovine skeletal myoblast proliferation, apoptosis and myogenic differentiation, which can contribute to further understanding the roles of m⁶A in skeletal muscle development.

Abstract

N⁶-methyladenosine (m⁶A) plays an important role in regulating gene expression. Previous studies found that m⁶A methylation affects skeletal muscle development. However, the effect of m⁶A methylases on bovine skeletal myogenesis is still unclear. Here, we found that the expression of m⁶A demethylases (FTO and ALKBH5) was significantly higher in the longissimus dorsi muscle of adult cattle than in newborn cattle. In contrast, the expression of m⁶A methyltransferases (METTL3, METTL14 and WTAP) was reduced. The mRNA expression of all five genes was found to be increased during the myogenesis of myoblasts in vitro. Knockdown of FTO or METTL3 promoted myoblast proliferation, inhibited myoblast apoptosis and suppressed myogenic differentiation, whereas ALKBH5 knockdown had the opposite effect. METTL14 knockdown enhanced myoblast proliferation and impaired myogenic differentiation. WTAP knockdown attenuated proliferation and contributed to apoptosis but did not affect differentiation. Furthermore, the functional domains of these five m⁶A methylases are conserved across species. Our results suggest that m⁶A methylases are involved in regulating skeletal muscle development and that there may be a complex network of m⁶A methylation regulating skeletal myogenesis.

Roles of RNA Modifications in Diverse Cellular Functions

Chemical modifications of RNA molecules regulate both RNA metabolism and fate. The deposition and function of these modifications are mediated by the actions of writer, reader, and eraser proteins. At the cellular level, RNA modifications regulate several cellular processes including cell death, proliferation, senescence, differentiation, migration, metabolism, autophagy, the DNA damage response, and liquid-liquid phase separation. Emerging evidence demonstrates that RNA modifications play active roles in the physiology and etiology of multiple diseases due to their pervasive roles in cellular functions. Here, we will summarize recent advances in the regulatory and functional role of RNA modifications in these cellular functions, emphasizing the context-specific roles of RNA modifications in mammalian systems. As m6A is the best studied RNA modification in biological processes, this review will summarize the emerging advances on the diverse roles of m6A in cellular functions. In addition, we will also provide an overview for the cellular functions of other RNA modifications, including m5C and m1A. Furthermore, we will also discuss the roles of RNA modifications within the context of disease etiologies and highlight recent advances in the development of therapeutics that target RNA modifications. Elucidating these context-specific functions will increase our understanding of how these modifications become dysregulated during disease pathogenesis and may provide new opportunities for improving disease prevention and therapy by targeting these pathways.

Emerging role of m6 A modification in cardiovascular diseases

Cardiovascular diseases (CVDs) contribute to the leading cause of death worldwide. Despite significantly improvements in CVDs diagnosis and treatment, a continued effort to explore novel therapeutic strategies is urgently need. N6-methyladenosine (m⁶ A) RNA methylation, well known as the most prevalent type of RNA modifications, involved in RNA stability, nuclear exports, translation and decoy, plays a crucial role in the pathogenesis of a variety of diseases, including CVDs, cancer and drug resistance. Here, our article summarizes cellular functions of m⁶ A modulators and recent research progress concerning the functions and mechanisms of m⁶ A methylation in CVDs, in hope of providing references for exploring novel therapeutic approaches and potential biomarkers in the treatment of CVDs. This article is protected by copyright. All rights reserved.

Comprehensive Analysis of the Transcriptome-Wide m6A Methylation Modification Difference in Liver Fibrosis Mice by High-Throughput m6A Sequencing

N6-Methyladenosine (m6A), a unique and common mRNA modification method in eukaryotes, is involved in the occurrence and development of many diseases. Liver fibrosis (LF) is a common response to chronic liver injury and may lead to cirrhosis and even liver cancer. However, the involvement of m6A methylation in the development of LF is still unknown. In this study, we performed a systematic evaluation of hepatic genome-wide m6A modification and mRNA expression by m6A-seq and RNA-seq using LF mice. There were 3,315 genes with significant differential m6A levels, of which 2,498 were hypermethylated and 817 hypomethylated. GO and KEGG analyses illustrated that differentially expressed m6A genes were closely correlated with processes such as the endoplasmic reticulum stress response, PPAR signaling pathway and TGF-β signaling pathway. Moreover, a total of 90 genes had both a significant change in the m6A level and mRNA expression shown by joint analysis of m6A-seq and RNA-seq. Hence, the critical elements of m6A modification, including methyltransferase WTAP, demethylases ALKBH5 and binding proteins YTHDF1 were confirmed by RT-qPCR and Western blot. In an additional cell experiment, we also observed that the decreased expression of WTAP induced the development of LF as a result of promoting hepatic stellate cell (HSC) activation. Therefore, this study revealed unique differential m6A methylation patterns in LF mice and suggested that m6A methylation was associated with the occurrence and course of LF to some extent.

N6 -Methyladenosine and Rheumatoid Arthritis: A Comprehensive Review

Rheumatoid arthritis (RA), one of the most common autoimmune diseases, is characterized by immune cell infiltration, fibroblast-like synovial cell hyperproliferation, and cartilage and bone destruction. To date, numerous studies have demonstrated that immune cells are one of the key targets for the treatment of RA. N⁶-methyladenosine (m⁶A) is the most common internal modification to eukaryotic mRNA, which is involved in the splicing, stability, export, and degradation of RNA metabolism. m⁶A methylated-related genes are divided into writers, erasers, and readers, and they are critical for the regulation of cell life. They play a significant role in various biological processes, such as virus replication and cell differentiation by controlling gene expression. Furthermore, a growing number of studies have indicated that m⁶A is associated with the occurrence of numerous diseases, such as lung cancer, bladder cancer, gastric cancer, acute myeloid leukemia, and hepatocellular carcinoma. In this review, we summarize the history of m6A research and recent progress on RA research concerning m⁶A enzymes. The relationship between m⁶A enzymes, immune cells, and RA suggests that m⁶A modification offers evidence for the pathogenesis of RA, which will help in the development of new therapies for RA.

MicroRNA-501-3p inhibits the proliferation of kidney cancer cells by targeting WTAP

BACKGROUND

Emerging evidence suggests that miR-501-3p plays an important role in the pathogenesis and progression of various carcinomas. However, its role and underlying mechanisms in renal cell carcinoma (RCC) remain to be elucidated.

METHODS

Quantitative RT-PCR, western blot, and bioinformatics methods were used to evaluate the expression of miR-501-3p and Wilms' tumor 1-associating protein (WTAP) in RCC cell lines and clinical tissues. The effects of miR-501-3p on the proliferation of RCC cells were investigated using flow cytometric, colony formation, and CCK8 assays. The target gene of miR-501-3p was confirmed by western blotting, qRT-PCR, and dual-luciferase reporter assays. The levels of RNA methylation with N6-methyladenosine (m⁶ A) following miR-501-3p overexpression or knockdown of its target gene were quantified using a dot-blot assay.

RESULTS

miR-501-3p expression was significantly downregulated in human RCC cell lines and tissues. In contrast, its overexpression markedly inhibited cancer cell proliferation in vitro by inducing G1 phase arrest. Moreover, WTAP was verified as a direct target gene of miR-501-3p. WTAP gene knockdown alone efficiently produced the same cancer-inhibiting effects as miR-501-3p overexpression, with the level of m⁶ A in RCC cells being decreased under both scenarios. The intermolecular interaction between miR-501-3p and WTAP was further substantiated by rescue experiments.

CONCLUSION

RCC progression is regulated via the miR-501-3p/WTAP/CDK2 axis and is inhibited by the overexpression of miR-501-3p.

Wilms' Tumor 1-Associating Protein complex regulates alternative splicing and polyadenylation at potential G-quadruplex-forming splice site sequences

Wilms’ tumor 1-associating protein (WTAP) is a core component of the N6-methyladenosine (m6A)-methyltransferase complex, along with VIRMA, CBLL1, ZC3H13 (KIAA0853), RBM15/15B, and METTL3/14, which generate m6A, a key RNA modification that affects various processes of RNA metabolism. WTAP also interacts with splicing factors; however, despite strong evidence suggesting a role of Drosophila WTAP homolog fl(2)d in alternative splicing (AS), its role in splicing regulation in mammalian cells remains elusive. Here we demonstrate using RNAi coupled with RNA-seq that WTAP, VIRMA, CBLL1, and ZC3H13 modulate AS, promoting exon skipping and intron retention in AS events that involve short introns/exons with higher GC content and introns with weaker polypyrimidine-tract and branch points. Further analysis of GC-rich sequences involved in AS events regulated by WTAP, together with minigene assay analysis, revealed potential G-quadruplex formation at splice sites where WTAP has an inhibitory effect. We also found that several AS events occur in the last exon of one isoform of MSL1 and WTAP, leading to competition for polyadenylation. Proteomic analysis also suggested that WTAP/CBLL1 interaction promotes recruitment of the 3′-end processing complex. Taken together, our results indicate that the WTAP complex regulates AS and alternative polyadenylation via inhibitory mechanisms in GC-rich sequences.

The methylation modification of m6A regulators contributes to the prognosis of head and neck squamous cell carcinoma

Background

N6-methyladenosine (m6A) regulation is a common type of messenger ribonucleic acid (mRNA) modification, and has been proven to contribute to the malignant behavior of tumors. However, the expression pattern and the prognostic role of m6A RNA methylation regulators in head and neck squamous cell carcinoma (HNSCC) remains unclear.

Methods

We downloaded the data of 422 patients from The Cancer Genome Atlas (TCGA) database. The relationship between the expression level of m6A RNA methylation regulators and clinicopathological variables in HNSCC was analyzed by R language.

Results

The m6A gene alteration was significantly correlated with tumor grade and tumor stage. Next, a least absolute shrinkage and selection operator (LASSO) Cox regression model was used to identify three m6A RNA methylation regulators [i.e., methyltransferase-like 14 (METTL14), methyltransferase-like 3 (METTL3), and heterogeneous nuclear ribonucleoproteins C1/C2 (HNRNPC)] to construct a risk signature. Based on the risk signature, the patients were classified into high- and low-risk groups. The overall survival (OS) rate of the low-risk group was significantly higher than that of the high-risk group. Additionally, the risk panel was an independent prognostic marker in HNSCC patients.

Conclusions

The m6A RNA methylation regulators are involved in HNSCC cancer progression. Further and more importantly, the risk signature comprising the three selected m6A RNA methylation regulators could serve as a potential marker to predict HNSCC patient outcomes.

EBV downregulates the m6A "writer" WTAP in EBV-associated gastric carcinoma

Epstein-Barr virus-associated gastric carcinoma (EBVaGC) is characterized by the clonal growth of EBV-infected stomach epithelial cells. It has been reported that N⁶-methyladenosine (m⁶A) methylation can regulate the splicing, expression, decay and translation of mRNAs. Wilms' tumor 1-associating protein (WTAP) is an m⁶A "writer" with methyltransferase activity. An m⁶A RNA methylation quantification kit and immunofluorescence (IF) showed that the m⁶A total RNA methylation level of the Epstein-Barr virus-negative gastric carcinoma (EBVnGC) cell line (SGC7901) was higher than that in the EBVaGC cell line (GT38). To investigate the underlying mechanism of the downregulated expression of m⁶A RNA methylation, we analyzed the expression of WTAP. The results showed that the expression of WTAP protein in EBVaGC cell lines was significantly lower than that in EBVnGC cell lines according to western blotting and IF. Through plasmid overexpression and RNA interference technology, we further found that EBV-encoded small RNA1 (EBER1) could downregulate WTAP expression by activating the NF-κB signaling pathway. In addition, WTAP could increase proliferation and inhibit migration in gastric carcinoma cell lines. In summary, EBER1 of EBV potentially regulated WTAP by affecting the NF-κB signaling pathway and WTAP further affected cell proliferation and migration.

Role of m6A in osteoporosis, arthritis and osteosarcoma (Review)

RNA modification is a type of post-transcriptional modification that regulates important cellular pathways, such as the processing and metabolism of RNA. The most abundant form of methylation modification is RNA N6-methyladenine (m6A), which plays various post-transcriptional regulatory roles in cellular biological functions, including cell differentiation, embryonic development and disease occurrence. Bones play a pivotal role in the skeletal system as they support and protect muscles and other organs, facilitate movement and ensure haematopoiesis. The development and remodelling of bones require a delicate and accurate regulation of gene expression by epigenetic mechanisms that involve modifications of histone, DNA and RNA. The present review discusses the enzymes and proteins involved in mRNA m6A methylation modification and summarises current research progress and the mechanisms of mRNA m6A methylation in common orthopaedic diseases, including osteoporosis, arthritis and osteosarcoma.

WTAP Function in Sertoli Cells Is Essential for Sustaining the Spermatogonial Stem Cell Niche

Sertoli cells are the major component of the spermatogonial stem cell (SSC) niche; however, regulatory mechanisms in Sertoli cells that dictate SSC fate decisions remain largely unknown. Here we revealed features of the N⁶-methyladenosine (m⁶A) mRNA modification in Sertoli cells and demonstrated the functions of WTAP, the key subunit of the m⁶A methyltransferase complex in spermatogenesis. m⁶A-sequencing analysis identified 21,909 m⁶A sites from 15,365 putative m⁶A-enriched transcripts within 6,122 genes, including many Sertoli cell-specific genes. Conditional deletion of Wtap in Sertoli cells resulted in sterility and the progressive loss of the SSC population. RNA sequencing and ribosome nascent-chain complex-bound mRNA sequencing analyses suggested that alternative splicing events of transcripts encoding SSC niche factors were sharply altered and translation of these transcripts were severely dysregulated by Wtap deletion. Collectively, this study uncovers a novel regulatory mechanism of the SSC niche and provide insights into molecular interactions between stem cells and their cognate niches in mammals.

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WTAP is highly expressed in Sertoli cell and is essential in spermatogenesis

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Wtap knockout in Sertoli cell causes defective spermatogonial stem cell maintenance

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WTAP regulates transcription and translation of m⁶A-enriched genes in Sertoli cell

Loss of WTAP Impairs Early Parthenogenetic Embryo Development

m⁶A is one of the most common and abundant modifications of RNA molecules present in eukaryotes. The methyltransferase complex, consisting of methyltransferase-like 3 (METTL3), METTL14, and WTAP, is responsible for the m⁶A modification of RNA. WTAP was identified as an mRNA splicing regulator. Its role as a regulatory subunit of the m⁶A methyltransferase complex in embryonic development remains largely unknown. To investigate the role of WTAP in porcine early embryonic development, si-WTAP was microinjected into porcine parthenogenetic zygotes. WTAP knockdown significantly reduced the blastocyst rate and global m⁶A levels, but did not affect the cleavage rate. Betaine was supplemented into the in vitro culture (IVC) to increase the m⁶A levels. Betaine significantly increased the global m⁶A levels but did not affect the blastocyst rate. Furthermore, the pluripotency genes, including OCT4, SOX2, and NANOG, were downregulated following WTAP knockdown. The apoptotic genes BAX and CASPASE 3 were upregulated, while the anti-apoptotic gene BCL2 was downregulated in WTAP knockdown blastocysts. TUNEL staining revealed that the number of apoptotic cells was significantly increased following WTAP knockdown. Our study indicated that WTAP has an indispensable role in porcine early embryonic development.

Gene Signatures and Prognostic Values of m6A RNA Methylation Regulators in Ovarian Cancer

BACKGROUND

N6-methyladenosine (m6A) is the most common form of mRNA modification under the field of "RNA epigenetics." However, its role in ovarian cancer (OC) development is poorly understood. In the current study, we aimed to identify gene signatures and prognostic values of m6A RNA methylation regulators.

METHOD

Specifically, we downloaded Mutations and Copy number variant (CNV) data from the TCGA database for 579 OC patients, then analyzed gene expression and prognosis value using integrative bioinformatics. Thereafter, we verified the related biological processes of Wilms' tumor 1-associating protein (WTAP) gene using Gene set enrichment analysis (GSEA).

RESULTS

Results showed that almost all ovarian cancer patients (99.31%) have CNVs with at least 1 m6A regulatory gene, whereas 83.76% of cases exhibited concurrence of CNVs in more than 4 m6A regulatory genes. Additionally, alteration of m6A regulators was associated with historical grade, whereas integrative bioinformatics and Cox multivariate model analysis revealed a significant correlation between high WTAP expression and worse ovarian cancer outcomes. Moreover, GSEA revealed that high WTAP expression was associated with cell cycle regulation and MYC targets.

CONCLUSION

Overall, our findings demonstrate the significance of high-frequency genetic alterations of m6A RNA methylation regulators and WTAP's poor prognosis value in OC. These findings provide valuable insights into the role of m6A methylation in OC, and will be vital in guiding development of novel treatment therapies.

miR-139-5p Loss-Mediated WTAP Activation Contributes to Hepatocellular Carcinoma Progression by Promoting the Epithelial to Mesenchymal Transition

Background: Hepatocellular carcinoma (HCC) is a primary aggressive gastrointestinal neoplasm that affects patients worldwide. It has been shown that Wilms' tumor 1-associating protein (WTAP) is frequently upregulated in various cancers. However, the potential role of WTAP in HCC remains largely unknown. Methods: The expression levels of WTAP in human HCC tissues were determined by the western blotting and immunohistochemical (IHC) staining. A correlation between the WTAP expression, clinicopathological features, and the HCC prognosis was analyzed. The WTAP expression was silenced by short hairpin RNA (shRNA), and effects of the knockdown of WTAP on the proliferation and invasion of HCC cells were assessed. The microRNAs (miRNAs) involved in the regulation of the WTAP expression were identified by a bioinformatics analysis and further confirmed by in vitro assays. Results: The expression levels of WTAP in liver cancer tissues were significantly elevated and compared with those in the adjacent normal tissues and significantly correlated with the clinical stage and prognosis in patients with HCC. Further investigation revealed that the knockdown of WTAP drastically suppressed HCC cell proliferation and invasion abilities. Luciferase reporter assay and validation experiments confirmed that WTAP was a direct target of miR-139-5p. Moreover, the overexpression of WTAP could partly abolish the inhibitory effects of miR-139-5p on the HCC cell growth and invasion. Mechanistically, we revealed that the miR-139-5p/WTAP axis regulated the HCC progression by controlling the epithelial to mesenchymal transition (EMT). Conclusions: In summary, the results indicate that WTAP is a potential oncogene in HCC and miR-139-5p negatively regulates the WTAP expression. MiR-139-5p/WTAP can be utilized as a potential therapeutic target for HCC.

Genetic variants in m6A modification core genes are associated with glioma risk in Chinese children

Glioma is a highly heritable disease with a strong genetic component. The N6-methyladenosine (m6A) modification core genes play important roles in the context of cancer. However, the effects of polymorphisms in the m6A modification core genes on the risk of pediatric glioma remain undefined. Here, we intended to demonstrate the relationship between 24 functional single-nucleotide polymorphisms (SNPs) in eight m6A modification core genes and glioma risk. Case-control design and multinomial logistic regression were used to develop models to estimate the risk of glioma while accounting for the subtypes of glioma. A total of 171 glioma cases and 228 controls from South China were genotyped using a TaqMan assay. The WTAP rs7766006, YTHDF2 rs3738067, and FTO rs9939609 variants conferred a statistically significant increased risk of glioma, respectively. YTHDC1 rs2293595, YTHDC1 rs3813832, and FTO rs8047395 were associated with a significant inverse association with risk of glioma, respectively. The significant associations were more predominant in stratification analyses of certain subgroups. Functional annotations revealed that WTAP rs7766006 and YTHDF2 rs3738067 could be potential functional variants by increasing expression of WTAP and YTHDF2 mRNA, respectively. Overall, these findings implicate variants in the m6A modification core genes as playing a role in pediatric glioma etiology.

Significance of RNA N6-Methyladenosine Regulators in the Diagnosis and Subtype Classification of Childhood Asthma Using the Gene Expression Omnibus Database

RNA N6-methyladenosine (m6A) regulators play important roles in a variety of biological functions. Nonetheless, the roles of m6A regulators in childhood asthma remain unknown. In this study, 11 significant m6A regulators were selected using difference analysis between non-asthmatic and asthmatic patients from the Gene Expression Omnibus GSE40888 dataset. The random forest model was used to screen five candidate m6A regulators (fragile X mental retardation 1, KIAA1429, Wilm's tumor 1-associated protein, YTH domain-containing 2, and zinc finger CCCH domain-containing protein 13) to predict the risk of childhood asthma. A nomogram model was established based on the five candidate m6A regulators. Decision curve analysis indicated that patients could benefit from the nomogram model. The consensus clustering method was performed to differentiate children with asthma into two m6A patterns (clusterA and clusterB) based on the selected significant m6A regulators. Principal component analysis algorithms were constructed to calculate the m6A score for each sample to quantify the m6A patterns. The patients in clusterB had higher m6A scores than those in clusterA. Furthermore, we found that the patients in clusterA were linked to helper T cell type 1 (Th1)-dominant immunity while those in clusterB were linked to Th2-dominant immunity. In summary, m6A regulators play nonnegligible roles in the occurrence of childhood asthma. Our investigation of m6A patterns may be able to guide future immunotherapy strategies for childhood asthma.

Wilms' Tumor 1-Associated Protein Contributes to Chemo-Resistance to Cisplatin Through the Wnt/β-Catenin Pathway in Endometrial Cancer

BACKGROUND

Cisplatin remains the mainstay of endometrial cancer (EC) chemotherapy. Wilms' tumor 1-associated protein (WTAP), playing a critical role in transcriptional and post-transcriptional regulation, has been reported as an oncogene, and its expression is elevated in multiple types of human tumors. Recent evidence has shown that the increased expression of WTAP is also closely related to chemo-resistance. However, its specific role in the susceptibility of human EC cells to cisplatin remains largely unexplored.

METHODS

WTAP over-expression and WTAP depletion cell lines as well as their corresponding controls were constructed by transfection with lentivirus. Western blotting analysis and quantitative real-time polymerase chain reaction (qRT-PCR) were employed to detect the expression of WTAP. Cell proliferation assay, colony formation assay, cell cycle assay, and apoptosis analysis were adopted to evaluate the effect of WTAP on the chemo-sensitivity of EC cells to cisplatin as well as its underlying mechanism. Immunofluorescence staining was used to assess the translocation of β-catenin. Moreover, a subcutaneous xenograft tumor model was established to assess the effect of WTAP on tumor growth after cisplatin treatment.

RESULTS

Depletion of WTAP in RL95-2 cells significantly enhanced the chemo-susceptibility of cells to cisplatin and increased the cell apoptosis, while WTAP over-expression in ARK-2 cells exhibited the opposite effects. Additionally, WTAP depletion significantly suppressed xenograft-tumor growth and enhanced sensitivity and apoptosis of tumor cells in vivo. Mechanistic analysis exhibited that WTAP over-expression facilitated the cytoplasm-to-nucleus translocation of β-catenin and enhanced the GSK3β phosphorylation at Ser9, while WTAP depletion revealed the opposite results, indicating that WTAP rendered chemo-resistance of EC cells to cisplatin by promoting the Wnt/β-catenin pathway.

CONCLUSIONS

WTAP might promote the chemo-resistance of EC cells to cisplatin through activating the Wnt/β-catenin pathway. Collectively, our findings offered novel insights into EC treatment.