WTAP and METTL14 regulate the m6A modification of DKK3 in renal tubular epithelial cells of diabetic nephropathy.

Diabetic nephropathy (DN) is an important cause of death in diabetes patients, which is mainly due to its complex pathogenesis. Here, we explored the role of N6-methyladenosine (m6A) RNA methylation in DN development. Renal tubular epithelial cells from DN patients and experimental DN mice treated with streptozotocin (STZ) exhibited a considerable increase in METTL14 and WTAP expression as well as overall m6A methylation. Knocking down the expression of METTL14 and WTAP inhibited the migration and proliferation of tubular epithelial cells. MeRIP-seq analysis of the renal tissues of DN patients revealed that the genes with elevated m6A methylation were concentrated in the Wnt/ß-Catenin signaling pathway. Dickkopf homolog 3 (DKK3) was screened out as the gene with the most significant increase in m6A methylation. In addition, the expression change pattern of DKK3 under DN circumstances is in line with those of METTL14 and WTAP. DKK3's m6A methylation sites were confirmed to be located in the 3'UTR region, which is how METTL14 and WTAP improved DKK3's mRNA stability. Finally, YTHDF1, a m6A reader, was demonstrated to recognize m6A-methylated DKK3 and promote DKK3 expression.

Dendrobine alleviates oleic acid-induced lipid accumulation by inhibiting FOS/METTL14 pathway.

Dendrobine (DDB), an alkaloid isolated from the Chinese herb Dendrobium, has antioxidant and anti-inflammatory effects; however, whether DDB reduces oleic acid (OA)-induced lipid accumulation remains unclear. OA-induced lipid accumulation model of HepG2 cells were treated with DDB. Cellular lipid deposition was assessed by Oil Red O (ORO) staining and triglyceride and total cholesterol detection. RNA-Sequencing (RNA-seq), biological function analysis, and transcription factor (TFs) prediction were combined to identify key TF in the DDB-treated OA model. Finally, the roles of FOS and METTL14 were examined using a DDB-induced lipid accumulation model. DDB inhibited OA-induced lipid accumulation. We identified 895 differentially expressed genes (DEGs) that were mainly enriched in various biological processes of lipid synthesis and transport. Four transcription factors (SOX9, MLXIPL, FOS, and JUN) associated with lipid metabolism and FOS levels in the OA-induced lipid accumulation model after DDB treatment had the greatest changes in expression change. Overexpression of FOS alleviates the inhibitory effect of DDB on OA-induced lipid accumulation. METTL14 is a target gene of FOS, and simultaneous interference with METTL14 in cells with high FOS expression restored the alleviating effect of DDB on lipid accumulation. DDB alleviated OA-induced lipid accumulation by inhibiting the FOS/METTL14 pathway.

METTL14 inhibits the proliferation, migration and invasion of prostate cancer cells by increasing m6A methylation of CDK4.

Background: Methyltransferase-like (METTL) plays an important role in various biological processes, but its role in prostate cancer (PCa) is still unclear. This study aimed to explore the mechanism by which methyltransferase-like 14 (METTL14) inhibits the physiological activity of PCa cells by increasing the N6-methyladenosine (m6A) modification of cyclin-dependent kinase 4 (CDK4). Methods: Clinical samples were collected for bioinformatics analysis. A PCa mouse model was constructed. Cell counting kit-8 (CCK-8), flow cytometry, colony formation assays, scratch assays, Transwell assays, real-time quantitative polymerase chain reaction (RT-qPCR), immunofluorescence and western blotting were used to detect the corresponding indicators. Results: METTL14 was found to be beneficial to inhibit the proliferation, invasion, and migration of PCa cells. When the m6A RNA increased, the half-life of CDK4 mRNA decreased after oe-METTL14 (overexpression of METTL14). Overexpression of CDK4 reversed the effect of oe-METTL14. Coimmunoprecipitation experiments revealed there were interactions between CDK4 and forkhead box M1 (FOXM1). Transfection of si-CDK4 was similar to transfection of oe-METTL14. After transfection with oe-FOXM1, the invasion and migration ability of cells increased, and cell apoptosis decreased. After transfection with si-FOXM1 alone, autophagy related 7 (ATG7) expression was significantly downregulated, and autophagy levels were reduced. The overexpression of ATG7 reversed the effect of si-FOXM1. The tumor volume and weight of the oe-METTL14 group mice were significantly reduced, and tumor proliferation was decreased in comparison to untreated tumor-bearing mice. Conclusions: METTL14 inhibits the invasion and migration of PCa cells and induces cell apoptosis by inhibiting CDK4 stability and FOXM1/ATG7-mediated autophagy.

Anticancer effects of Erzhimaoling decoction in high-grade serous ovarian cancer in vitro and in vivo.

BACKGROUND: High-grade serous ovarian cancer (HGSOC) is a common gynecologic malignancy with a poor prognosis. The traditional Chinese medicine formula Erzhimaoling decoction (EZMLD) has anticancer potential. This study aims to elucidate the anticancer effects of EZMLD on HGSOC in vitro and in vivo. MATERIALS AND METHODS: EZMLD-containing serum was prepared from Sprague-Dawley rats for treating SKOV3 ovarian cancer cells at varying concentrations for 24 h and 48 h to determine the IC50. Concentrations of 0%, 5%, and 10% for 24 h were chosen for subsequent in vitro experiments. The roles of METTL3 and METTL14 in SKOV3 cells were explored by overexpressing these genes and combining EZMLD with METTL3/14 knockdown. Investigations focused on cell viability and apoptosis, apoptosis-related protein expression, and KRT8 mRNA m6A modification. For in vivo studies, 36 BALB/c nude mice were divided into six groups involving EZMLD (6.75, 13.5, and 27 g/kg) and METTL3 or METTL14 knockdowns, with daily EZMLD gavage for two weeks. RESULTS: In vitro, EZMLD-containing serum had IC50 values of 8.29% at 24 h and 5.95% at 48 h in SKOV3 cells. EZMLD-containing serum decreased SKOV3 cell viability and increased apoptosis. EZMLD upregulated METTL3/14 and FAS-mediated apoptosis proteins, while downregulating Keratin 8 (KRT8). EZMLD increased KRT8 mRNA m6A methylation. METTL3/14 overexpression reduced SKOV3 cell viability and increased apoptosis, while METTL3/14 knockdown mitigated EZMLD's effects. In vivo, EZMLD suppressed SKOV3 xenografts growth, causing significant apoptosis and modulating protein expression. CONCLUSIONS: EZMLD has therapeutic potential for ovarian cancer and may be considered for other cancer types. Future research may explore its broader effects beyond cell apoptosis.

m6A modification of CDC5L promotes lung adenocarcinoma progression through transcriptionally regulating WNT7B expression.

Cell division cycle 5-like (CDC5L) protein is implicated in the development of various cancers. However, its role in the progression of lung adenocarcinoma (LUAD) remains uncertain. Our findings revealed frequent upregulation of CDC5L in LUAD, which correlated with poorer overall survival rates and advanced clinical stages. In vitro experiments demonstrated that CDC5L overexpression stimulated the proliferation, migration, and invasion of LUAD cells, whereas CDC5L knockdown exerted suppressive effects on these cellular processes. Furthermore, silencing CDC5L significantly inhibited tumor growth and metastasis in a xenograft mouse model. Mechanistically, CDC5L activates the Wnt/ß-catenin signaling pathway by transcriptionally regulating WNT7B, thereby promoting LUAD progression. Besides, METTL14-mediated m6A modification contributed to CDC5L upregulation in an IGF2BP2-dependent manner. Collectively, our study uncovers a novel molecular mechanism by which the m6A-induced CDC5L functions as an oncogene in LUAD by activating the Wnt/ß-catenin pathway through transcriptional regulation of WNT7B, suggesting that CDC5L may serve as a promising prognostic marker and therapeutic target for LUAD.

METTL14 contributes to the progression of nasopharyngeal carcinoma through regulating the stability of AOC1 mRNA.

BACKGROUND: Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor of the nasopharyngeal mucosa with a high incidence rate all over the world. Methyltransferase-like 14 (METTL14) is a major RNA N6-adenosine methyltransferase implicated in tumor progression by regulating RNA function. This study is designed to explore the biological function and mechanism of METTL14 in NPC. METHODS: METTL14 and Amine oxidase copper containing 1 (AOC1) expression were detected by real-time quantitative polymerase chain reaction (RT-qPCR). The protein levels of METTL14, AOC1, Cyclin D1, B-cell lymphoma-2 (Bcl-2), and N-cadherin were measured using western blot. Cell proliferation, cycle progression, apoptosis, migration, and invasion were assessed using 5-ethynyl-2'-deoxyuridine (EdU), Colony formation, flow cytometry, wound scratch, and transwell assays. The interaction between METTL14 and AOC1 was verified using RNA immunoprecipitation (RIP), methylated RNA immunoprecipitation (MeRIP), and dual-luciferase reporter assays. The biological role of METTL14 on NPC tumor growth was examined by the xenograft tumor model in vivo. RESULTS: METTL14 and AOC1 were highly expressed in NPC tissues and cells. Moreover, METTL14 knockdown might block NPC cell proliferation, migration, invasion, and induce cell apoptosis in vitro. In mechanism, METTL14 might enhance the stability of AOC1 mRNA via m6A methylation. METTL14 silencing might repress NPC tumor growth in vivo. CONCLUSION: METTL14 might boosted the development of NPC cells partly by regulating the stability of AOC1 mRNA, which provided a promising therapeutic target for NPC treatment.

METTL14-mediated upregulation of lncRNA HOTAIR represses PP1α expression by promoting H3K4me1 demethylation in oxycodone-treated mice.

N6-methyladenosine (m6A) methylation is a vital epigenetic mechanism associated with drug addiction. However, the relationship between m6A modification and oxycodone rewarding is less well explored. Based on an open field test, the present study evaluated oxycodone rewarding using chromatin immunoprecipitation PCR, immunofluorescence, and RNA sequencing. A marked increase in METTL14 protein and a decrease in PP1α protein due to oxycodone abundance in the striatal neurons were observed in a dose- and time-dependent manner. Oxycodone markedly increased LSD1 expression, and decreased H3K4me1 expression in the striatum. In the open field test, intra-striatal injection of METTL14 siRNA, HOTAIR siRNA, or LSD1 shRNA blocked oxycodone-induced increase in locomotor activity. The downregulation of PP1α was also inhibited after treatment with METTL14/HOTAIR siRNA and LSD1 shRNA. Enhanced binding of LSD1 with CoRest and of CoRest with the PP1α gene induced by oxycodone was also reversed by LSD1 shRNA. In addition, H3K4me1 demethylation was also blocked by the treatment. In summary, the investigation confirmed that METTL14-mediated upregulation of HOTAIR resulted in the repression of PP1α, which in turn facilitated the recruitment of LSD1, thus catalyzing H3K4me1 demethylation and promoting oxycodone addiction.

Unraveling the independent role of METTL3 in m6A modification and tumor progression in esophageal squamous cell carcinoma.

METTL3 and METTL14 are traditionally posited to assemble the m6A methyltransferase complex in a stoichiometric 1:1 ratio, modulating mRNA fate via m6A modifications. Nevertheless, recent investigations reveal inconsistent expression levels and prognostic significance of METTL3 and METTL14 across various tumor types, challenging their consistent functional engagement in neoplastic contexts. A pan-cancer analysis leveraging The Cancer Genome Atlas (TCGA) data has identified pronounced disparities in the expression patterns, functional roles, and correlations with tumor burden between METTL3 and METTL14, particularly in esophageal squamous cell carcinoma (ESCC). Knockdown experiments of METTL3 in EC109 cells markedly suppress cell proliferation both in vitro and in vivo, whereas METTL14 knockdown shows a comparatively muted effect on proliferation and does not significantly alter METTL3 protein levels. mRNA sequencing indicates that METTL3 singularly governs the expression of 1615 genes, with only 776 genes co-regulated with METTL14. Additionally, immunofluorescence co-localization studies suggest discrepancies in cellular localization between METTL3 and METTL14. High-performance liquid chromatography-mass spectrometry (HPLC-MS) analyses demonstrate that METTL3 uniquely associates with the Nop56p-linked pre-rRNA complex and mRNA splicing machinery, independent of METTL14. Preliminary bioinformatics and multi-omics investigations reveal that METTL3's autonomous role in modulating tumor cell proliferation and its involvement in mRNA splicing are potentially pivotal molecular mechanisms. Our study lays both experimental and theoretical groundwork for a deeper understanding of the m6A methyltransferase complex and the development of targeted tumor therapies focusing on METTL3.

METTL14 plays an oncogenic role in NSCLC by modulating ferroptosis and the m6A modification of GPX4.

CONTEXT: N6-methyladenosine (m6A) of RNA is involved in the progression of non-small cell lung cancer (NSCLC). OBJECTIVE: This study investigated the role of METTL14 in NSCLC and the mechanism. MATERIALS AND METHODS: Expression levels were assessed by quantitative real-time PCR and ELISA assays. Cells viability was assessed by cell counting kit-8. M6A methylation was analysed by methylated RNA immunoprecipitation (MeRIP), RIP, luciferase assay, and mRNA stability assay. RESULTS: The results showed that METTL14 was highly expressed in NSCLC tissues and cell lines. Knockdown of METTL14 inhibited the cell viability while induced ferroptosis of NSCLC cells. Mechanistically, METTL14 interacts with GPX4, mediates m6A modification of GPX4, enhances its mRNA stability, and upregulates its expression. In addition, IGF2BP1 recognises the m6A-methylated GPX4 and mediates the elevated mRNA stability. Moreover, GPX4 reversed the effects of METTL14 depletion. DISCUSSION AND CONCLUSION: The METTL14/GPX4 axis promotes NSCLC progression by inhibiting cell ferroptosis through the recognition of m6A modification mediated by IGF2BP1.

METTL14-mediated N6-methyladenosine modification of TCP1 mRNA promotes acute myeloid leukemia progression.

BACKGROUND: Acute myeloid leukemia (AML) is a prevalent hematologic malignancy characterized by a steady rise in morbidity and mortality rates over time. The upregulation of methyltransferase-like 14 (METTL14) expression in AML has been identified; however, its specific contributions to AML progression and underlying molecular mechanisms have yet to be elucidated. METHOD: METTL14-bound mRNAs were predicted using bioinformatics methods, analyzed, and screened to identify T-complex protein 1 (TCP1). The regulatory impact of METTL14 on TCP1 was observed. TCP1 expression in AML clinical samples was assessed using quantitative real-time PCR and western blot analysis. The involvement of TCP1 in AML malignant progression was assessed through in vitro and in vivo functional assays. The String database was utilized for predicting proteins that interact with TCP1, while western blot assays and immunoprecipitation were employed to validate the associated signaling pathways. RESULTS: METTL14 overexpression upregulates TCP1 expression in AML cells. AML patients exhibit high levels of TCP1 expression. Elevated TCP1 levels in HL60 and U937 cells in vitro lead to increased proliferation, migration, invasion, and inhibition of apoptosis, while in vivo, it accelerates AML proliferation and tumorigenesis. Mechanistically, METTL14 modulates AML progression by influencing TCP1 transcript stability via m6A methylation, thereby regulating TCP1 expression. Additionally, PPP2R2C potentially serves as a crucial functional target of TCP1 implicated in the malignant progression of AML. CONCLUSION: Upregulation of TCP1 expression in AML through METTL14-mediated m6A modification accelerates the malignant progression of the disease. Therefore, targeting the m6A modification of TCP1 could be a potential therapeutic strategy to enhance the treatment of AML.

METTL14 derived from exosomes of M1 macrophages promotes high glucose-induced apoptosis, inflammation and oxidative stress in glomerular endothelial cells by mediating PAQR3 m6A modification.

BACKGROUND: Methyltransferase 14 (METTL14) mediated N6-methyladenine (m6A) RNA methylation and progestin and AdipoQ receptor family member 3 (PAQR3) are reported to be involved in diabetic nephropathy (DN) progression. Here, we explored whether the effects of PAQR3 on DN was associated with METTL14-induced m6A and their relationship with macrophage-related exosomes in DN progression. METHODS: Human glomerular endothelial cells (GECs) were incubated in high glucose (HG) condition to mimic DN condition in vitro. Exosomes were isolated from M1 macrophages and co-cultured with GECs. qRT-PCR and western blotting detected the levels of genes and proteins. Cell functions were determined using cell counting kit-8 assay and flow cytometry. ELISA analysis detected inflammatory factors, and oxidative stress was evaluated by measuring reactive oxygen species and malondialdehyde. The m6A modification profile was determined by methylated RNA immunoprecipitation assay and the interaction was verified by dual-luciferase reporter assay. RESULTS: HG elevated PAQR3 expression levels in GECs. PAQR3 silencing reversed HG-induced viability arrest, apoptosis, inflammatory response, and oxidative stress. M1 macrophage co-culture could suppress HG-induced GEC injury. PAQR3 was packaged into M1 macrophage-derived exosomes, and M1 macrophages regulated HG-induced GEC injury by secreting PAQR3 into cells via exosomes. Mechanistically, METTL14 induced PAQR3 m6A modification. METTL14 was enriched in M1 macrophage-derived exosomes. METTL14 knockdown in M1 macrophage-derived exosomes protected GEC from HG-induced viability arrest, apoptosis, inflammation and oxidative stress by regulating PAQR3. CONCLUSION: Exosomal METTL14 derived from M1 macrophages promoted HG-induced apoptosis, inflammation and oxidative stress in GECs by mediating PAQR3 m6A modification.

METTL14 promotes lipid metabolism reprogramming and sustains nasopharyngeal carcinoma progression via enhancing m6A modification of ANKRD22 mRNA.

BACKGROUND: N6-methyladenosine (m6A) modification is essential for modulating RNA processing as well as expression, particularly in the context of malignant tumour progression. However, the exploration of m6A modification in nasopharyngeal carcinoma (NPC) remains very limited. METHODS: RNA m6A levels were analysed in NPC using m6A dot blot assay. The expression level of methyltransferase-like 14 (METTL14) within NPC tissues was analysed from public databases as well as RT-qPCR and immunohistochemistry. The influences on METTL14 expression on NPC proliferation and metastasis were explored via in vitro as well as in vivo functional assays. Targeted genes of METTL14 were screened using the m6A and gene expression profiling microarray data. Actinomycin D treatment and polysome analysis were used to detect the half-life and translational efficiency of ANKRD22. Flow cytometry, immunofluorescence and immunoprecipitation were used to validate the role of ANKRD22 on lipid metabolism in NPC cells. ChIP-qPCR analysis of H3K27AC signalling near the promoters of METTL14, GINS3, POLE2, PLEK2 and FERMT1 genes. RESULTS: We revealed METTL14, in NPC, correlating with poor patient prognosis. In vitro and in vivo assays indicated METTL14 actively promoted NPC cells proliferation and metastasis. METTL14 catalysed m6A modification on ANKRD22 messenger ribonucleic acid (mRNA), recognized by the reader IGF2BP2, leading to increased mRNA stability and higher translational efficiency. Moreover, ANKRD22, a metabolism-related protein on mitochondria, interacted with SLC25A1 to enhance citrate transport, elevating intracellular acetyl-CoA content. This dual impact of ANKRD22 promoted lipid metabolism reprogramming and cellular lipid synthesis while upregulating the expression of genes associated with the cell cycle (GINS3 and POLE2) and the cytoskeleton (PLEK2 and FERMT1) through heightened epigenetic histone acetylation levels in the nucleus. Intriguingly, our findings highlighted elevated ANKRD22-mediated histone H3 lysine 27 acetylation (H3K27AC) signals near the METTL14 promoter, which contributes to a positive feedback loop perpetuating malignant progression in NPC. CONCLUSIONS: The identified METTL14-ANKRD22-SLC25A1 axis emerges as a promising therapeutic target for NPC, and also these molecules may serve as novel diagnostic biomarkers.

ETS1 and RBPJ transcriptionally regulate METTL14 to suppress TGF-ß1-induced epithelial-mesenchymal transition in human bronchial epithelial cells.

Asthma is a chronic respiratory disease characterized by airway inflammation and remodeling. Epithelial-mesenchymal transition (EMT) of bronchial epithelial cells is considered to be a crucial player in asthma. Methyltransferase-like 14 (METTL14), an RNA methyltransferase, is implicated in multiple pathological processes, including EMT, cell proliferation and migration. However, the role of METTL14 in asthma remains uncertain. This research aimed to explore the biological functions of METTL14 in asthma and its underlying upstream mechanisms. METTL14 expression was down-regulated in asthmatic from three GEO datasets (GSE104468, GSE165934, and GSE74986). Consistent with this trend, METTL14 was decreased in the lung tissues of OVA-induced asthmatic mice and transforming growth factor-ß1 (TGF-ß1)-stimulated human bronchial epithelial cells (Beas-2B) in this study. Overexpression of METTL14 caused reduction in mesenchymal markers (FN1, N-cad, Col-1 and α-SMA) in TGF-ß1-treated cells, but caused increase in epithelial markers (E-cad), thus inhibiting EMT. Also, METTL14 suppressed the proliferation and migration ability of TGF-ß1-treated Beas-2B cells. Two transcription factors, ETS1 and RBPJ, could both bind to the promoter region of METTL14 and drive its expression. Elevating METTL14 expression could reversed EMT, cell proliferation and migration promoted by ETS1 or RBPJ deficiency. These results indicate that the ETS1/METTL14 and RBPJ/METTL14 transcription axes exhibit anti-EMT, anti-proliferation and anti-migration functions in TGF-ß1-induced bronchial epithelial cells, implying that METTL14 may be considered an alternative candidate target for the treatment of asthma.

METTL14 inhibits the malignant processes of gastric cancer cells by promoting N6-methyladenosine (m6A) methylation of TAF10.

N6-methyladenosine (m6A) methylation mediates cancer development by regulating cell proliferation and metastasis. This study aimed to identify whether methyltransferase 14 (METTL14) affects gastric cancer (GC) cellular functions and its underlying mechanism. METTL14 and TATA-box binding protein associated factor 10 (TAF10) levels were examined using quantitative real-time PCR, immunohistochemical assay, and Western blot. Biological functions were assessed using cell counting kit-8, colony formation, and transwell assays. The interaction between METTL14 and TAF10 was analyzed using RNA immunoprecipitation, methylated RNA immunoprecipitation, and luciferase reporter assay. A xenograft tumor mouse model was established to assess the role of METTL14 in vivo. The results suggested that METTL14 was low expressed and TAF10 was highly expressed in GC tissues and cells. METTL14 overexpression inhibited GC cell viability, colony, migration, and invasion. TAF10 was predicted and confirmed to be negatively related to METTL14. METTL14 promoted m6A methylation of TAF10 and inhibited TAF10 stability. Moreover, TAF10 counteracted the cellular behaviors regulated by METTL14. Overexpression of METTL14 inhibited tumor growth and histopathology. In conclusion, METTL14 inhibits GC progression by attenuating GC cell proliferation, migration, and invasion. Mechanistically, METTL14 promoted m6A methylation of TAF10, suppressed the stability of TAF10, and thus downregulated the TAF10 levels, These results provide a new insight into GC therapy.

METTL14 is Involved in TNF-α-Induced Inflammation in Colorectal Epithelial Cells via Autophagy Modulation.

Ulcerative colitis (UC) is a chronic and relapsing inflammatory bowel disease (IBD) characterized by colorectal inflammation. The N6-methyladenosine (m6A) modification of RNA regulates gene expression through the modulation of RNA metabolism, thus influencing various physiological and pathological processes. The aim of this study was to investigate the biological function of m6A methyltransferase METTL14 in colorectal epithelial cell inflammation. Bioinformatics analysis indicated that METTL14 expression was decreased in UC and was associated with disease severity and immune infiltration. We also noted a downregulation of METTL14 expression and a decrease in the total m6A RNA levels in TNF-α-stimulated Caco-2 cells. Moreover, METTL14 knockdown promoted inflammation and inhibited autophagy in TNF-α-stimulated Caco-2 cells, as indicated by the upregulation of NF-κB signaling and pro-inflammatory cytokine expression as well as LC3B protein downregulation. Treatment with the autophagy activator Torin-1 ameliorated the pro-inflammatory effects of METTL14 silencing. Furthermore, METTL14 knockdown significantly reduced the expression of ATG5. ATG5 overexpression could nullify the pro-inflammatory effect of METTL14 knockdown in TNF-α-stimulated Caco-2 cells. Mechanistically, METTL14 knockdown promoted ATG5 mRNA degradation, and luciferase analysis identified ATG5 as a target of m6A modification by METTL14. Taken together, silencing METTL14 promoted inflammation in Caco-2 cells via the downregulation of ATG5. Our findings revealed the importance of the m6A modification in colonic inflammation and autophagy, indicating that targeting METTL14 might be a potential therapeutic strategy for anti-inflammatory treatment in UC.

METTL14-mediated methylation of SLC25A3 mitigates mitochondrial damage in osteoblasts, leading to the improvement of osteoporosis.

PURPOSE: Osteoporosis is linked to impaired function of osteoblasts, and decreased expression of METTL14 may result in abnormal differentiation of these bone-forming cells. However, the specific impact of METTL14 on osteoblast differentiation and its underlying mechanisms are not yet fully understood. METHODS AND RESULTS: This study discovered a positive correlation between METTL14 expression and bone formation in specimens from osteoporosis patients and ovariectomized (OVX) mice. Additionally, METTL14 targeting of SLC25A3 contributed to the restoration of mitochondrial ROS levels and mitochondrial membrane potential in osteoblasts and promoted osteoblast differentiation. Moreover, in vivo experiments showed that METTL14 enhanced bone formation, and therapeutic introduction of METTL14 countered the decrease in bone formation in OVX mice. CONCLUSIONS: Overall, these findings emphasize the crucial role of the METTL14/SLC25A3 signaling axis in osteoblast activity, suggesting that this axis could be a potential target for improving osteoporosis.

Icariin upregulates methyltransferase-like 14-mediated prolyl 4-hydroxylase beta subunit m6A modification to promote osteogenic differentiation of bone marrow stem cells.

Prolyl 4-hydroxylase beta subunit (P4HB) plays a vital role in bone formation. This study intends to clarify the role of P4HB in the therapeutic effect of Icariin (ICA) on osteoporosis. Herein, in vivo and in vitro models were constructed by performing ovariectomy (OVX) in rats and inducing osteogenic differentiation in bone marrow stem cells (BMSCs), respectively. Hematoxylin and eosin staining and micro-computed tomography analysis were performed to evaluate osteoporosis in OVX rats. Alizarin Red staining, alkaline phosphatase staining, and the ALP activity test were employed to assess osteogenesis. m6A dot blotting and methylated RNA immunoprecipitation were used to determine m6A modification. We found that P4HB was downregulated in bone tissues of patients with osteoporosis and OVX rats. P4HB facilitated osteogenic differentiation of BMSCs. What's more, ICA upregulated P4HB expression, promoted osteogenic differentiation of BMSCs, and alleviated osteoporosis in OVX rats, which were reversed by knocking down P4HB. ICA enhanced the stability and m6A modification of P4HB. METTL14 mediated m6A modification of P4HB mRNA. In addition, METTL14 knockdown overturned the promotive effects of ICA on P4HB m6A level and BMSC osteogenic differentiation. To sum up, ICA elevated the METTL14-mediated m6A modification of P4HB to facilitate BMSC osteogenic differentiation.

Methyltransferase like-14 suppresses growth and metastasis of non-small-cell lung cancer by decreasing LINC02747.

Multiple epigenetic regulatory mechanisms exert critical roles in tumor development, and understanding the interactions and impact of diverse epigenetic modifications on gene expression in cancer is crucial for the development of precision medicine. We found that methyltransferase-like 14 (METTL14) was significantly downregulated in non-small-cell lung cancer (NSCLC) tissues. Functional experiments demonstrated that overexpression of METTL14 inhibited the proliferation and migration of NSCLC cells both in vivo and in vitro, and the colorimetric m6A quantification assay also showed that knockdown of METTL14 notably reduced global m6A modification levels in NSCLC cells. By using the methylated-RNA immunoprecipitation-qPCR and dual-luciferase reporter assays, we verified that long noncoding RNA LINC02747 was a target of METTL14 and was regulated by METTL14-mediated m6A modification, and silencing LINC02747 inhibited the malignant progression of NSCLC by modulating the PI3K/Akt and CDK4/Cyclin D1 signaling pathway. Further studies revealed that overexpression of METTL14 promoted m6A methylation and accelerated the decay of LINC02747 mRNA via increased recognition of the "GAACU" binding site by YTHDC2. Additionally, histone demethylase lysine-specific histone demethylase 5B (KDM5B) mediated the demethylation of histone H3 lysine 4 tri-methylation (H3K4me3) in the METTL14 promoter region and repressed its transcription. In summary, KDM5B downregulated METTL14 expression at the transcriptional level in a H3K4me3-dependent manner, while METTL14 modulated LINC02747 expression via m6A modification. Our results demonstrate a synergy of multiple mechanisms in regulating the malignant phenotype of NSCLC, revealing the complex regulation involved in the occurrence and development of cancer.

METTL14 mediates nerve growth factor-stimulated testosterone synthesis in porcine theca cells.

Ovarian theca cells produce testosterone, which acts as a vital precursor substance for synthesizing estrogens during follicular development. Nerve growth factor (NGF) has been shown to participate in reproductive physiology, specifically to follicular development and ovulation. There is currently no available data on the impact of NGF on testosterone synthesis in porcine theca cells. Furthermore, m6A modification is the most common internal modification in eukaryotic mRNAs that are closely associated with female gametogenesis, follicle development, ovulation, and other related processes. It is also uncertain whether the three main enzymes associated with m6A, such as Writers, Erasers and Readers, play a role in this process. The present study, with an in vitro culture model, investigated the effect of NGF on testosterone synthesis in porcine theca cells and the role of Writers-METTL14 in this process. It was found that NGF activates the PI3K/AKT signaling pathway through METTL14, which regulates testosterone synthesis in porcine theca cells. This study will help to further elucidate the mechanisms by which NGF regulates follicular development and provide new therapeutic targets for ovary-related diseases in female animals.

METTL14/YTHDC1-Mediated m6A Modification in Hippocampus Improves Pentylenetetrazol-Induced Acute Seizures.

Epilepsy is a common neurological disorder which can cause significant morbidity and mortality. N6-methyladenosine (m6A), the most common chemical epigenetic modification among mRNA post-transcriptional modifications, implicated in various physiological and pathological processes, but its role in epilepsy is still unknown. Here, we provide strong evidences in support of an association of m6A and its regulatory proteins with epilepsy. Our results indicated that the level of m6A was declined significantly in the dentate gyrus (DG) of hippocampus of pentylenetetrazol (PTZ)-induced seizure mice. Both the seizure-like behaviors and the excessive activation of DG area neuron were significantly mitigated after the administration of m6A agonist betaine. Mechanically, we found that both the m6A methyltransferase METTL14 and recognition protein YTHDC1 were decreased by PTZ stimulation, which might contribute to the reduced m6A level. Additionally, DG-specific over-expression of METTL14 or YTHDC1 by lentivirus injection could significantly ameliorate seizure-like behaviors and prevent the excessive activation of neuron in epilepsy mice induced by PTZ injection, which might be due to the normalized m6A level. Together, this study identified that METTL14/YTHDC1-mediated m6A modification could participate in seizure-like behaviors, which might provide m6A regulation as a potential and novel therapeutic strategy for epilepsy.