bims-rimeca 2023-07-30 papers

bims-rimeca

Biomed News

on RNA methylation in cancer

Issue of 2023–07–30
fiveteen papers selected by
Sk Ramiz Islam, Saha Institute of Nuclear Physics

N6-Methyladenosine Directly Regulates CD40L Expression in CD4+ T Lymphocytes.
Multilevel regulation of N6-methyladenosine RNA modifications: Implications in tumorigenesis and therapeutic opportunities.
Recognition of the Subtypes Classification and Diagnostic Signature Based on RNA N6-Methyladenosine Regulators in Recurrent Spontaneous Abortion.
METTL3-Mediated Maturation of miR-99a-5p Promotes Cell Migration and Invasion in Oral Squamous Cell Carcinoma by Targeting ZBTB7A.
Downregulation of FTO in the hippocampus is associated with mental disorders induced by fear stress during pregnancy.
HPV E7-drived ALKBH5 promotes cervical cancer progression by modulating m6A modification of PAK5.
FTO-mediated m6A modification alleviates autoimmune uveitis by regulating microglia phenotypes via the GPC4/TLR4/NF-κB signaling axis.
N6-adenosine methylation controls the translation of insulin mRNA.
Homogeneous Electrochemiluminescence for Highly Sensitive Determination of Demethylase FTO Based on Target-Regulated DNAzyme Cleavage and Host-Guest Interaction.
Insights into the role of N6-methyladenosine in ferroptosis.
Exosomal microRNAs in tubal fluid may be involved in damage to tubal reproductive function associated with tubal endometriosis.
EZH2 Contributes to Anoikis Resistance and Promotes Epithelial Ovarian Cancer Peritoneal Metastasis by Regulating m6A.
NAT10-mediated RNA acetylation enhances HNRNPUL1 mRNA stability to contribute cervical cancer progression.
Decreased expression of Chrna4 by METTL3-mediated m6A modification participates in BPA-induced spatial memory deficit.
SETD2 controls m6A modification of transcriptome and regulates the molecular oncogenesis of glioma.

Biology (Basel). 2023 Jul 14. pii: 1004. [Epub ahead of print]12(7):

N6-Methyladenosine Directly Regulates CD40L Expression in CD4+ T Lymphocytes.

Ellen C N van Vroonhoven, Lucas W Picavet, Rianne C Scholman, Noortje A M van den Dungen, Michal Mokry, Anouk Evers, Robert J Lebbink, Jorg J A Calis, Sebastiaan J Vastert, Jorg van Loosdregt.

  T cell activation is a highly regulated process, modulated via the expression of various immune regulatory proteins including cytokines, surface receptors and co-stimulatory proteins. N6-methyladenosine (m6A) is an RNA modification that can directly regulate RNA expression levels and it is associated with various biological processes. However, the function of m6A in T cell activation remains incompletely understood. We identify m6A as a novel regulator of the expression of the CD40 ligand (CD40L) in human CD4+ lymphocytes. Manipulation of the m6A 'eraser' fat mass and obesity-associated protein (FTO) and m6A 'writer' protein methyltransferase-like 3 (METTL3) directly affects the expression of CD40L. The m6A 'reader' protein YT521-B homology domain family-2 (YTHDF2) is hypothesized to be able to recognize and bind m6A specific sequences on the CD40L mRNA and promotes its degradation. This study demonstrates that CD40L expression in human primary CD4+ T lymphocytes is regulated via m6A modifications, elucidating a new regulatory mechanism in CD4+ T cell activation that could possibly be leveraged in the future to modulate T cell responses in patients with immune-related diseases.

Keywords:  CD40 ligand; RNA methylation; T cell activation; adaptive immunity; autoimmunity; epitranscriptomics

DOI:  https://doi.org/10.3390/biology12071004
Genes Dis. 2023 Sep;10(5): 1969-1981

Multilevel regulation of N6-methyladenosine RNA modifications: Implications in tumorigenesis and therapeutic opportunities.

Lili Feng, Rongrong Du, Baitong Chang, Min Li, Jie Tian, Shengjun Wang.

  N6-methyladenosine (m6A) RNA modification is widely perceived as the most abundant and common modification in transcripts. This modification is dynamically regulated by specific m6A "writers", "erasers" and "readers" and is reportedly involved in the occurrence and development of many diseases. Since m6A RNA modification was discovered in the 1970s, with the progress of relevant research technologies, an increasing number of functions of m6A have been reported, and a preliminary understanding of m6A has been obtained. In this review, we summarize the mechanisms through which m6A RNA modification is regulated from the perspectives of expression, posttranslational modification and protein interaction. In addition, we also summarize how external and internal environmental factors affect m6A RNA modification and its functions in tumors. The mechanisms through which m6A methylases, m6A demethylases and m6A-binding proteins are regulated are complicated and have not been fully elucidated. Therefore, we hope to promote further research in this field by summarizing these mechanisms and look forward to the future application of m6A in tumors.

Keywords:  N6-methyladenosine (m6A); RNA modification; Regulatory mechanisms; Therapy; Tumor

DOI:  https://doi.org/10.1016/j.gendis.2022.08.018
Reprod Sci. 2023 Jul 24.

Recognition of the Subtypes Classification and Diagnostic Signature Based on RNA N6-Methyladenosine Regulators in Recurrent Spontaneous Abortion.

Zitao Wang, Fangfang Dai, Hua Liu, Yanxiang Cheng.

  Recurrent spontaneous abortion (RSA) is a common reproductive disease in female patients that seriously affects the quality of life of patients. N6-methyladenosine (m6A), as the most common modification, plays an important role in various biological behaviors; however, the relationship between m6A and RSA is still unknown. In the present study, we utilized RNA sequencing data and clinical information of RSA patients and normal women in the GEO database to identify the expression profiles of m6A regulators in RSA. Based on the m6A regulators' expression profiles, we constructed a random forest model consisting of 4 genes to predict the prevalence of RSA patients, including FMR1, METTL14, LRPPRC, and RBMX. The predictive performance of the nomogram was constructed and validated. Not only that, consensus clustering was performed to divide RSA patients into 3 clusters based on the expression of m6A regulators and calculated the m6A scores and immune infiltration of patients in different clusters. It was found that the TH1-type immune response was dominant in the A cluster, the B-type immune activity was poor, and the C cluster was the strongest. In addition, on the basis of m6A typing, we further used the differentially expressed genes between clusters to perform consensus clustering verification, and the results were consistent with the previous findings. In conclusion, the m6A regulators played an indispensable role in the occurrence of RSA, and the m6A-based typing could effectively identify the immune characteristics of different RSA patients to a certain extent, providing a new direction and strategy for the diagnosis and treatment of RSA patients.

Keywords:  Consensus clustering; Immune microenvironment; N6-methyladenosine; Recurrent spontaneous abortion; Signature

DOI:  https://doi.org/10.1007/s43032-023-01271-3
Mol Biotechnol. 2023 Jul 27.

METTL3-Mediated Maturation of miR-99a-5p Promotes Cell Migration and Invasion in Oral Squamous Cell Carcinoma by Targeting ZBTB7A.

Yuhua Huang, Yun Guan, Xing Zhang.

  METTL3 is an important methyltransferase in N(6)-methyladenosine (m6A) modification. Recently, METTL3 mediates methylation of pri-microRNA (miRNA) to accelerate miRNA maturation, regulating tumor development. This study explored whether METTL3 mediated miR-99a-5p to influence oral squamous cell carcinoma (OSCC) cell metastasis. MiR-99a-5p, ZBTB7A, and MATTL3 expression was measured using quantitative real-time PCR. Biological behaviors were assessed using cell counting kit-8, flow cytometry, Transwell assay, as well as western blot. Luciferase reporter assay evaluated the interaction between miR-99a-5p and ZBTB7A. METTL3-regulated pri-miR-99a-5p processing was determined by RNA binding protein immunoprecipitation (RIP) and methylated RNA immunoprecipitation (MeRIP) assays. The consequences clarified that miR-99a-5p was upregulated in OSCC cells. Downregulation of miR-99a-5p suppressed cellular viability, migration, invasion, and epithelial-mesenchymal transition (EMT), and induced apoptosis. ZBTB7A acted as a miR-99a-5p target and reversed the effects on cellular behaviors induced by miR-99a-5p inhibitor. m6A content and METTL3 expression were increased in OSCC cells. METTL3 promoted the m6A modification of pri-miR-99a-5p and thereby facilitated miR-99a-5p processing. Moreover, knockdown of METTL3 inhibited OSCC metastasis by downregulating miR-99a-5p. Taken together, METTL3 promoted miR-99a-5p maturation in an m6A-dependent manner, which further targets ZBTB7A to accelerate the progression of OSCC. These findings suggest potential targets for OSCC therapy.

Keywords:  METTL3; Metastasis; Oral squamous cell carcinoma; ZBTB7A; miR-99a-5p

DOI:  https://doi.org/10.1007/s12033-023-00815-x
Behav Brain Res. 2023 Jul 26. pii: S0166-4328(23)00316-9. [Epub ahead of print] 114598

Downregulation of FTO in the hippocampus is associated with mental disorders induced by fear stress during pregnancy.

Yu Jiang, Tong Zhang, Liping Yang, Zhixin Du, Qiyang Wang, Junlin Hou, Yuexuan Liu, Qi Song, Jiajia Zhao, Yongye Wu.

  Mental disorders (MD), such as anxiety, depression, and cognitive impairment, are very common during pregnancy and predispose to adverse pregnancy outcomes; however, the underlying mechanisms are still under intense investigation. Although the most common RNA modification in epigenetics, N6-methyladenosine (m6A) has been widely studied, its role in MD has not been investigated. Here, we observed that fat mass and obesity-associated protein (FTO) are downregulated in the hippocampus of pregnant rats with MD induced by fear stress and demonstrated that FTO participates in and regulates MD induced by fear stress. In addition, we identified four genes with anomalous modifications and expression (double aberrant genes) that were directly regulated by FTO, namely Angpt2, Fgf10, Rpl21, and Adcy7. Furthermore, we found that these genes might induce MD by regulating the PI3K/Akt and Rap1 signaling pathways. It appears that FTO-mediated m6A modification is a key regulatory mechanism in MD caused by fear stress during pregnancy.

Keywords:  FTO; MeRIP-Seq; N6-methyladenosine; double aberrant genes; hippocampus; mental disorders

DOI:  https://doi.org/10.1016/j.bbr.2023.114598
Pharmacol Res. 2023 Jul 20. pii: S1043-6618(23)00219-0. [Epub ahead of print] 106863

HPV E7-drived ALKBH5 promotes cervical cancer progression by modulating m6A modification of PAK5.

Fu-Chun Huo, Zhi-Man Zhu, Wen-Qi Du, Yao-Jie Pan, Xin Jiang, Meng-Jie Kang, Bo-Wen Liu, Jie Mou, Dong-Sheng Pei.

  Human papillomavirus (HPV) infection is a causative agent of cervical cancer (CC). N6-methyladenosine (m6A) modification is implicated in carcinogenesis and tumor progression. However, the involvement of m6A modification in HPV-involved CC remains unclear. Here we showed that HPV E6/7 oncoproteins affected the global m6A modification and E7 specifically promoted the expression of ALKBH5. We found that ALKBH5 was significantly upregulated in CC and might serve as a valuable prognostic marker. Forced expression of ALKBH5 enhanced the malignant phenotypes of CC cells. Mechanistically, we discovered that E7 increased ALKBH5 expression through E2F1-mediated activation of the H3K27Ac and H3K4Me3 histone modifications, as well as post-translational modification mediated by DDX3. ALKBH5-mediated m6A demethylation enhanced the expression of PAK5. The m6A reader YTHDF2 bound to PAK5 mRNA and regulated its stability in an m6A-dependent manner. Moreover, ALKBH5 promoted tumorigenesis and metastasis of CC by regulating PAK5. Overall, our findings herein demonstrate a significant role of ALKBH5 in CC progression in HPV-positive cells. Thus, we propose that ALKBH5 may serve as a prognostic biomarker and therapeutic target for CC patients.

Keywords:  ALKBH5; Cervical cancer; DDX3; PAK5; m6A methylation

DOI:  https://doi.org/10.1016/j.phrs.2023.106863
Genes Dis. 2023 Sep;10(5): 2179-2193

FTO-mediated m6A modification alleviates autoimmune uveitis by regulating microglia phenotypes via the GPC4/TLR4/NF-κB signaling axis.

Siyuan He, Wanqian Li, Guoqing Wang, Xiaotang Wang, Wei Fan, Zhi Zhang, Na Li, Shengping Hou.

  Uveitis, a vision-threatening inflammatory disease worldwide, is closely related to resident microglia. Retinal microglia are the main immune effector cells with strong plasticity, but their role in uveitis remains unclear. N6-methyladenosine (m6A) modification has been proven to be involved in the immune response. Therefore, we in this work aimed to identify the potentially crucial m6A regulators of microglia in uveitis. Through the single-cell sequencing (scRNA-seq) analysis and experimental verification, we found a significant decrease in the expression of fat mass and obesity-associated protein (FTO) in retinal microglia of uveitis mice and human microglia clone 3 (HMC3) cells with inflammation. Additionally, FTO knockdown was found to aggravate the secretion of inflammatory factors and the mobility/chemotaxis of microglia. Mechanistically, the RNA-seq data and rescue experiments showed that glypican 4 (GPC4) was the target of FTO, which regulated microglial inflammation mediated by the TLR4/NF-κB pathway. Moreover, RNA stability assays indicated that GPC4 upregulation was mainly regulated by the downregulation of the m6A "reader" YTH domain family protein 3 (YTHDF3). Finally, the FTO inhibitor FB23-2 further exacerbated experimental autoimmune uveitis (EAU) inflammation by promoting the GPC4/TLR4/NF-κB signaling axis, and this could be attenuated by the TLR4 inhibitor TAK-242. Collectively, a decreased FTO could facilitate microglial inflammation in EAU, suggesting that the restoration or activation of FTO function may be a potential therapeutic strategy for uveitis.

Keywords:  Fat mass and obesity-associated protein; Glypican 4; Microglia; N6-methyladenosine; Uveitis; YTH domain Family protein 3

DOI:  https://doi.org/10.1016/j.gendis.2022.09.008
Nat Struct Mol Biol. 2023 Jul 24.

N6-adenosine methylation controls the translation of insulin mRNA.

Daniel Wilinski, Monica Dus.

Control of insulin mRNA translation is crucial for energy homeostasis, but the mechanisms remain largely unknown. We discovered that insulin mRNAs across invertebrates, vertebrates and mammals feature the modified base N6-methyladenosine (m6A). In flies, this RNA modification enhances insulin mRNA translation by promoting the association of the transcript with polysomes. Depleting m6A in Drosophila melanogaster insulin 2 mRNA (dilp2) directly through specific 3' untranslated region (UTR) mutations, or indirectly by mutating the m6A writer Mettl3, decreases dilp2 protein production, leading to aberrant energy homeostasis and diabetic-like phenotypes. Together, our findings reveal adenosine mRNA methylation as a key regulator of insulin protein synthesis with notable implications for energy balance and metabolic disease.

DOI: https://doi.org/10.1038/s41594-023-01048-x
Anal Chem. 2023 Jul 24.

Homogeneous Electrochemiluminescence for Highly Sensitive Determination of Demethylase FTO Based on Target-Regulated DNAzyme Cleavage and Host-Guest Interaction.

Xia Yang, Shuai Qiao, Wei Zhao, Sijia Li, Yanxia Qiao, Yang Jiang, Yaqian Zhou, Yan Li.

Fat mass and obesity-associated protein (FTO) is the first reported N6-methyladenosine (m6A) RNA demethylase. The dysregulation of FTO demethylation is strongly associated with various human cancers in a m6A-dependent manner. Herein, a homogeneous electrochemiluminescence (ECL) method for the determination of FTO was proposed based on the target-regulated DNAzyme cleavage. Moreover, the ECL signal was highly enhanced by host-guest interaction between β-cyclodextrin (β-CD) and tri-n-propylamine (TPrA). The m6A caged DNAzyme 17E-Me acted as a padlock, while the FTO served as the corresponding key. As the key, FTO could specifically remove m6A modification, restoring the cleavage activity of DNAzyme 17E. With the assistance of the Zn2+ cofactor, the substrate strand was cleaved at a specific site, and the ECL indicator of Ru(phen)32+ was discharged to produce an ECL signal. On the contrary, 17E-Me was blocked and no cleavage reaction occurred without the key. For the ECL detection, the electrode modification of β-CD@AuNPs concentrated Ru(phen)32+ species through electrostatic adsorption and gathered TPrA molecules through host-guest interaction with β-CD, which resulted in an intense ECL response. The results demonstrated the ECL intensity linearly correlated with the logarithm of the FTO concentration (from 0.0001 to 100 nM) with a low detection limit (30 fM). The IC50 value for FTO inhibitors rhein and meclofenamic acid were 35.6 μM and 20.3 μM, respectively. The strategy was further validated for FTO detection in MCF-7 cell lysates and Hela cell lysates. This work reveals that this strategy is promising for developing homogeneous ECL method for detection of FTO and screening of the demethylase inhibitors.

DOI: https://doi.org/10.1021/acs.analchem.3c01661
Biomed Pharmacother. 2023 Jul 22. pii: S0753-3322(23)00983-6. [Epub ahead of print]165 115192

Insights into the role of N6-methyladenosine in ferroptosis.

Jingyuan Zhang, Tianming Qiu, Xiaofeng Yao, Xiance Sun.

  N6-methyladenosine (m6A) methylation modification is one of the most prevalent epigenetic modifications of eukaryotic RNA. m6A methylation is widely associated with many biological processes through the modification of RNA metabolism and is associated with multiple disease states. As a newly discovered regulatory cell death in recent years, ferroptosis is an iron-dependent cell death characterized by excessive lipid peroxidation. Emerging evidence supports that ferroptosis has a significant role in the progression of diverse diseases. Besides, the key regulators of ferroptosis exhibit aberrant m6A levels under different pathological conditions. However, the correlation between m6A-modified ferroptosis and multiple diseases has not been well elucidated. In this review, we summarized the functions of m6A in ferroptosis, which are associated with the initiation and progression of multiple diseases. Investigating the role of m6A in ferroptosis might both facilitate a better understanding of the pathogenesis of these diseases and provide new opportunities for targeted treatment.

Keywords:  Ferroptosis; M(6)A demethylase; M(6)A methyltransferase; M(6)A-binding proteins; N6-methyladenosine

DOI:  https://doi.org/10.1016/j.biopha.2023.115192
Reprod Biomed Online. 2023 Jun 23. pii: S1472-6483(23)00351-6. [Epub ahead of print] 103249

Exosomal microRNAs in tubal fluid may be involved in damage to tubal reproductive function associated with tubal endometriosis.

Yiqin Zhang, Huiyu Zhang, Li Yan, Guiling Liang, Chenfeng Zhu, Yang Wang, Sifan Ji, Chuqing He, Jing Sun, Jian Zhang.

   RESEARCH QUESTION: What is the effect of tubal endometriosis on tubal epithelial ultrastructure and is there a differential expression of exosomal microRNAs (miRNAs) in tubal fluid which may affect tubal infertility?
DESIGN: Human fallopian tube epithelium and tubal fluid samples were obtained from patients with and without tubal endometriosis. Scanning electron microscopy and transmission electron microscopy were used to assess ultrastructural changes. Exosomal miRNAs in tubal fluid were extracted for microarray.
RESULTS: Epithelial damage was visualized in the tubal endometriosis group using electron microscopy. The number of organelles decreased (P = 0.0314), and organelle structure was destroyed. A total of 14 differentially expressed exosomal miRNAs were detected in tubal fluid (fold change >2 and P < 0.05). Four miRNAs (miR-1273f, miR-5699-5p, miR-6087 and miR-6747-5p) were validated by quantitative real-time polymerase chain reaction. Bioinformatic analysis showed that most of the target genes participated in embryo transport, regulation of cell communication, anatomical structure morphogenesis and immune system processes.
CONCLUSIONS: Tubal endometriosis results in damage to the tubal epithelial ultrastructure in human specimens and the presence of differentially expressed exosomal miRNAs in tubal liquid. These findings help to clarify the pathogenesis of tubal endometriosis-associated infertility and the mechanisms driving tubal epithelial ultrastructure damage in tubal endometriosis.

Keywords:  electron microscopy; exosome; infertility; miRNA; tubal endometriosis; ultrastructure

DOI:  https://doi.org/10.1016/j.rbmo.2023.06.004
Curr Med Sci. 2023 Jul 27.

EZH2 Contributes to Anoikis Resistance and Promotes Epithelial Ovarian Cancer Peritoneal Metastasis by Regulating m6A.

Shao-Hai Wang, Lin Liu, Ke-Yong Bao, Yi-Fan Zhang, Wen-Wen Wang, Shi Du, Na-Er Jia, Suo Suo, Jing Cai, Jian-Feng Guo, Gang Lv.

   OBJECTIVE: Histone modification has a significant effect on gene expression. Enhancer of zeste homolog 2 (EZH2) contributes to the epigenetic silencing of target chromatin through its roles as a histone-lysine N-methyltransferase enzyme. The development of anoikis resistance in tumor cells is considered to be a critical step in the metastatic process of primary malignant tumors. The purpose of this study was to investigate the effect and mechanism of anoikis resistance in ovarian adenocarcinoma peritoneal metastasis.
METHODS: In addition to examining EZH2 protein expression in ovarian cancer omental metastatic tissues, we established a model of ovarian cancer cell anoikis and a xenograft tumor model in nude mice. Anoikis resistance and ovarian cancer progression were tested after EZH2 and N6-methyladenosine (m6A) levels were modified.
RESULTS: EZH2 expression was significantly higher in ovarian cancer omental metastatic tissues than in normal ovarian tissues. Reducing the level of EZH2 decreased the level of m6A and ovarian cancer cell anoikis resistance in vitro and inhibited ovarian cancer progression in vivo. M6a regulation altered the effect of EZH2 on anoikis resistance.
CONCLUSION: Our results indicate that EZH2 contributes to anoikis resistance and promotes ovarian adenocarcinoma abdominal metastasis by m6A modification. Our findings imply the potential of the clinical application of m6A and EZH2 for patients with ovarian cancer.

Keywords:  N6-methyladenosine; anoikis; enhancer of zeste homolog 2; heterografts; ovarian neoplasms

DOI:  https://doi.org/10.1007/s11596-023-2719-4
Int J Med Sci. 2023 ;20(8): 1079-1090

NAT10-mediated RNA acetylation enhances HNRNPUL1 mRNA stability to contribute cervical cancer progression.

Yingfei Long, Yifei Ren, Qinglv Wei, Youchaou Mobet, Yujiao Liu, Hongyan Zhao, Tao Liu, Lei Cheng, Ping Yi.

  N4-acetylcytidine (ac4C) is a lately discovered nucleotide modification that has been shown to be closely implicated in cancer. N-acetyltransferase10(NAT10) acts as an enzyme that regulates mRNA acetylation modifications. Currently, the role of NAT10-mediated RNA acetylation modification in cervical cancer remains to be elucidated. On the basis of transcriptome analysis of TCGA and GEO open datasets (GSE52904, GSE29570, GSE122697), NAT10 is upregulated in cervical cancer tissues and correlated with poor prognosis. Knockdown of NAT10 suppressed the cell proliferation, invasion, and migration of cervical cancer cells. The in vivo oncogenic function of NAT10 was also confirmed in xenograft models. Combined RNA-seq and acRIP-seq analysis revealed HNRNPUL1 as the target of NAT10 in cervical cancer. NAT10 positively regulate HNRNPUL1 expression by promoting ac4C modification and stability of HNRNPUL1 mRNA. Furthermore, depletion of HNRNPUL1 suppressed the cell division, invasion, and migration of cervical cancer. HNRNPUL1 overexpression partially restored cellular function in cervical cancer cells with NAT10 knockdown. Thus, this study demonstrates that NAT10 contributes to cervical cancer progression by enhancing HNRNPUL1 mRNA stability via ac4C modification, and NAT10-ac4C-HNRNPUL1 axis might be a potential target for cervical cancer therapy.

Keywords:  HNRNPUL1; N4-acetylcytidine (ac4C); NAT10; cervical cancer; mRNA stability

DOI:  https://doi.org/10.7150/ijms.83828
Environ Res. 2023 Jul 24. pii: S0013-9351(23)01521-9. [Epub ahead of print] 116717

Decreased expression of Chrna4 by METTL3-mediated m6A modification participates in BPA-induced spatial memory deficit.

Danyang Li, Chengqing Huang, Zhihua Liu, Shu Ai, Hui-Li Wang.

  Bisphenol A (BPA), a widely used endocrine disruptor, has been implicated in cognitive impairment via epigenetic machinery. N6-methyl adenosine (m6A) has recently emerged as a new epigenetic factor that influences cognition, but the role of m6A in BPA induced cognitive deficits has not been explored yet. In this study, we found increased global m6A abundance accompanied with elevated expression of methyltransferase-like 3 (METTL3) in hippocampal neurons following BPA exposure. Inhibition of METTL3 activity by selective METTL3 inhibitor 2457 (STM) in cultured neurons abolished BPA induced m6A upregulation and abnormal synaptic transmission. Additionally, knockdown of METTL3 in hippocampus abrogated BPA induced learning and memory deficit in rats. Further study showed that m6A modification was enriched in mRNA of cholinergic receptor nicotinic alpha 4 subunit (Chrna4). Inhibition of METTL3 either by STM or shRNA restored BPA induced downregulation of Chrna4, suggesting that Chrna4 may be a potential target involved in BPA induced neurotoxicity that modified by m6A. Collectively, our findings demonstrated that METTL3 mediated m6A modification was involved in BPA induced cognitive deficit with Chrna4 as a potential target, which enriched our understanding of the role of epigenetics (RNA modifications) in BPA induced neurotoxicity and provided new insights into BPA or its substitutes induced damages in other organs.

Keywords:  BPA; Chrna4; METTL3; Memory deficits; m6A

DOI:  https://doi.org/10.1016/j.envres.2023.116717
Med Oncol. 2023 Jul 25. 40(9): 249

SETD2 controls m6A modification of transcriptome and regulates the molecular oncogenesis of glioma.

Subhadra Kumari, Mandakini Singh, Santosh Kumar, Srinivasan Muthuswamy.

  SETD2 is known for its epigenetic regulatory function and a frequently mutated gene in multiple cancers. Recently, it has been inferred that SETD2 regulates m6A mRNA methylation (epitranscriptome) via H3K36me3. The m6A RNA methylation is vital for tumor maintenance, self-renewal, and tumorigenesis. RNA modifications are executed by writers, readers, and erasers. m6A modifiers work along with the molecular cues, H3K36me3, laid down by SETD2. A positive correlation observed between SETD2 and RNA modifiers signifies their direct role in epitranscriptomics. Hence, understanding the epitranscriptomics will provide a new facet for molecular oncogenesis. Glioma is a common, malignant grade IV tumor with limited therapeutic alternatives and a poor prognosis. Yet, its function in glioma is not fully defined. In the present study, thorough investigations were done in the m6A RNA methylation regulators expression, the molecular pathways leading to tumor progression, and their respective outcomes in SETD2-mediated RNA methylation. In vitro analysis reveals that SETD2 knockdown positively affected the oncogenic properties of the glioma cell line and a global reduction in m6A levels in the transcriptome. The reduction of m6A in the transcriptome can be attributed to the decreased expression of METTL3 and METTL14. Therefore, we conclude that SETD2-mediated m6A modifications are crucial for glioma oncogenesis.

Keywords:  Epitranscriptomics; Glioma; SETD2; m6A RNA methylation

DOI:  https://doi.org/10.1007/s12032-023-02121-7