Research progress on m5C methylation and its prospects in tumor immunotherapy / 口腔疾病防治

@#Epigenetic modification plays an important role in the biological regulatory process of eukaryotic cells. Tumor immunotherapy is an important means and clinical strategy for the treatment of some cancers. 5-Methylcytosine (m5C) is an important component of the epigenetic regulatory network discovered after m6A and has become a new topic for life science research in recent years. The m5C methylation of RNA can affect the fate of the modified RNA molecules and play an important role in various biological processes, including RNA stability, protein synthesis and transcriptional regulation. Recent studies have shown that m5C writers, erasers and readers are related to a variety of cellular biological processes and systemic diseases, including the occurrence, metastasis and tumor immune microenvironment. m5C methylation can widely affect gene expression and the biological process of tumorigenesis and development at multiple levels, but its specific mechanism and potential interaction with other epigenetic modifications in tumor immunotherapy are still unclear, and its regulatory mechanism, risk assessment and role in targeted therapy for malignant tumors need to be further studied. This article will review the dynamic regulatory network of m5C, the biological role of m5C modification in solid tumors and potential targets in tumor immunotherapy.

Modification of m6 A in human embryonic lung fibroblasts induced by neodymium oxide exposure and its mechanism / 环境与职业医学

Background Occupational and environmental particulate matter may cause fibrosis, accompanied by RNA m6A modification changes. Neodymium oxide (Nd2O3) can cause mouse lung fibrosis, which contains a large number of fibroblasts. Objective To investigate m6A modification of tumor necrosis factor receptor-associated protein 6/nuclear factor-κB (TRAF6/NF-κB) signaling pathway in fibrosis of human embryonic lung fibroblasts induced by Nd2O3, and identify the key m6A modification sites of TRAF6. Methods Designed concentrations of Nd2O3 (0, 1.563, 3.125, 6.25, 12.5, 25, 50, 100, and 200 mg∙L−1) were infected with HELF cells for 24 and 48 h, and cell viability was detected to determine exposure time and dose. Measurements included indicators of fibrosis [hydroxyproline (HYP) and transforming growth factor-β1 (TGF-β1)], m6A methylation level, methyltransferases (METTL3 and METTL14), demethylases (FTO and ALKBH5), reading proteins (YTHDC2 and YTHDF2), fibrosis-associated genes (collagen-І, vimentin, and α-SMA), and proteins related to signaling pathway (TRAF6, NFKB1, P65, and P-P65). The enrichment of m6A in TRAF6 mRNA was measured by methylated RNA immunoprecipitation-quantitative real-time PCR (MeRIP-qPCR). Results The results of cell viability indicated that 6.25, 12.5, 25 mg∙L−1 Nd2O3 and 48 h exposure time were used for subsequent experiments. After 48 h exposure, compared with the control group, the HYP level in the 25 mg∙L−1 Nd2O3 group was increased, and the levels of TGF-β1 in the 6.25, 12.5, and 25 mg∙L−1 Nd2O3 groups were increased (P<0.05); the overall m6A methylation levels of HELF cells in the 12.5 and 25 mg∙L−1 Nd2O3 groups were increased (P<0.05). At mRNA level, compared with the control group, the mRNA expression levels of methyltransferases METTL3 and METTL14 (6.25, 12.5, and 25 mg∙L−1 Nd2O3) were increased (P<0.05); the mRNA expression level of reading protein YTHDF2 (6.25, 12.5, and 25 mg∙L−1 Nd2O3) was increased (P<0.05), while the mRNA expression level of YTHDC2 (25 mg∙L−1 Nd2O3) was decreased (P<0.05); the mRNA expression levels of demethylases FTO (12.5 and 25 mg∙L−1 Nd2O3) and ALKBH5 (25 mg∙L−1 Nd2O3) were decreased (P<0.05); the mRNA expression levels of fibrosis-related genes vimentin, α-SMA, and collagen-Ⅰ (6.25, 12.5, and 25 mg∙L−1 Nd2O3) were increased (P<0.05); the mRNA expression levels of pathway-related genes TRAF6 (25 mg∙L−1 Nd2O3) and NFKB1 (12.5 and 25 mg∙L−1 Nd2O3) were increased (P<0.05). At protein level, compared with the control group, the expression levels of methyltransferases METTL3 (25 mg∙L−1 Nd2O3) and METTL14 (12.5 and 25 mg∙L−1 Nd2O3) were increased (P<0.05); the expression level of reading protein YTHDF2 (12.5 and 25 mg∙L−1 Nd2O3) was increased, while the expression level of YTHDC2 (25 mg∙L−1 Nd2O3) was decreased (P<0.05); the expression level of demethylase FTO (25 mg∙L−1 Nd2O3) was decreased (P<0.05); the expression level of fibrosis-associated protein vimentin was increased at 25 mg∙L−1 Nd2O3, and the expression levels of α-SMA and collagen-Ⅰ were increased at 12.5 and 25 mg∙L−1 Nd2O3 (P<0.05); the expression levels of TRAF6 and P-P65 were increased at 25 mg∙L−1 Nd2O3 (P<0.05). The MeRIP-qPCR results showed that compared with the control group, the concentrations of m6A in all Nd2O3 groups were significantly increased (P<0.05). Conclusions Upon exposure of HELF cells to Nd2O3, the alterations in fibrosis-related indexes increase the expression of some m6A methylases and decrease the expression of demethylases, thereby increasing the m6A methylase level, and may promote the progression of fibrosis by activating the TRAF6/NF-κB signaling pathway.

Research progress of m6A methylation in prostate cancer / 亚洲男科学杂志(英文版)

N6-methyladenosine (m6A) is a ubiquitous RNA modification in mammals. This modification is "written" by methyltransferases and then "read" by m6A-binding proteins, followed by a series of regulation, such as alternative splicing, translation, RNA stability, and RNA translocation. At last, the modification is "erased" by demethylases. m6A modification is essential for normal physiological processes in mammals and is also a very important epigenetic modification in the development of cancer. In recent years, cancer-related m6A regulation has been widely studied, and various mechanisms of m6A regulation in cancer have also been recognized. In this review, we summarize the changes of m6A modification in prostate cancer and discuss the effect of m6A regulation on prostate cancer progression, aiming to profile the potential relevance between m6A regulation and prostate cancer development. Intensive studies on m6A regulation in prostate cancer may uncover the potential role of m6A methylation in the cancer diagnosis and cancer therapy.

Role of N6-methyladenosine RNA methylation in central nervous system: a review / 生物工程学报

There are a variety of post-transcriptional modifications in mRNA, which regulate the stability, splicing, translation, transport and other processes of mRNA, followed by affecting cell development, body immunity, learning and cognition and other important physiological functions. m6A modification is one of the most abundant post-transcriptional modifications widely existing in mRNA, regulating the metabolic activities of RNA and affecting gene expression. m6A modified homeostasis is critical for the development and maintenance of the nervous system. In recent years, m6A modification has been found in neurodegenerative diseases, mental diseases and brain tumors. This review summarizes the role of m6A methylation modification in the development, function and related diseases of the central nervous system in recent years, providing potential clinical therapeutic targets for neurological diseases.

Inhibitory Effect and Mechanism of Sishenwan-containing Serum on Aerobic Glycolysis in Human Colon Cancer Cells / 中国实验方剂学杂志

ObjectiveTo explore the effect and mechanism of Sishenwan-containing serum on aerobic glycolysis in human colon cancer HCT116 cells. MethodCell counting kit-8 （CCK-8） was used to detect the cell viability of colon cancer HCT116 cells after treatment with Sishenwan-containing serum （2.5%， 5%， and 10%） for 24， 48， 72 h. The concentration of lactic acid， the content of intracellular glucose， and the activity of hexokinase （HK） and fructose-6-phosphate kinase （PFK） in the cell culture medium were detected by the micro-method. The content of glucose transporter 1 （GluT1） mRNA was detected by Real-time quantitative polymerase chain reaction （Real-time PCR）. The protein expression of GluT1 and methyltransferase-like 3 （MettL3） was detected by Western blot. The expression of GluT1 in cells was detected by immunofluorescence and the level of N6-methyladenosine （m6A） RNA methylation was detected by colorimetry. ResultCompared with the normal serum， 2.5%， 5%， and 10% Sishenwan-containing serum had no significant effect on the viability of HCT116 cells at 24 h， while 10% Sishenwan-containing serum showed a significant inhibitory effect on the viability of HCT116 cells at 48 h （P<0.05）. Hence， 10% Sishenwan-containing serum was used in subsequent experiments， and the intervention time was 48 h. Compared with the normal serum， 10% Sishenwan-containing serum could reduce lactate production （P<0.05）， down-regulate glucose uptake （P<0.05）， and blunt the activities of HK and PFK， the key rate-limiting enzymes of glycolysis （P<0.05）. Meanwhile， 10% Sishenwan-containing serum could decrease the expression of GluT1 protein （P<0.01） and mRNA （P<0.05） and reduce the proportion of cells expressing GluT1 （P<0.01）. Compared with the normal serum， Sishenwan-containing serum also decreased the protein content of MettL3 （P<0.05） and the methylation level of m6A RNA （P<0.01）. ConclusionSishenwan can inhibit glycolysis in colon cancer cells， and its inhibitory mechanism may be related to reducing MettL3 overexpression， inhibiting m6A RNA methylation， and down-regulating GluT1 and the activities of intracellular aerobic glycolysis-related enzymes such as HK and PFK.

METTL3 promotes hyperoxia-induced pyroptosis in neonatal bronchopulmonary dysplasia by inhibiting ATG8-mediated autophagy

Abstract Objectives N6-Methyladenosine (m6A) modification plays a vital role in lung disorders. However, the potential of m6A in neonatal Bronchopulmonary Dysplasia (BPD) has not been reported. This study aimed to investigate the roles of METTL3 in BPD. Methods BPD models were established by hyperoxia in vivo and in vitro. Histological analysis was determined using HE staining. Gene expression was determined using Western blotting, qRT-PCR, and immunofluorescence. The release of IL-1β and IL-18 was detected using ELISA. The m6A sites of ATG8 were predicted by SCRAPM and verified by MeRIP assay. The location of GSDMD and ATG8 was determined by FISH assay. The interaction between ATG8 and GSDMD was detected using Coimmunoprecipitation (Co-IP). Cell pyroptosis was determined using flow cytometry and TUNEL assays. Results METTL3 was overexpressed in BPD, which was accompanied by an increase in m6A levels. Interestingly, METTL3 suppressed hyperoxia-mediated damage and pyroptosis in BEAS-2B cells and promoted cell autophagy. METTL3-mediated m6A modification of ATG8 suppressed its expression and disrupted the interaction between ATG8 and GSDMD. However, autophagy inhibition induced pyroptosis in BEAS-2B cells. In vivo assays showed that METTL3-mediated autophagy inhibition induced a decrease in the radial alveolar count and an increase in the mean linear intercept and promoted cell pyroptosis. Conclusion In conclusion, METTL3-mediated cell pyroptosis promotes BPD by regulating the m6A modification of ATG8. This may provide new insight into the development of BPD.

Mechanism of m6A methyltransferase 3 in the pathogenesis of diabetic cataract / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the role and mechanism of N6-methyladenosine(m6A)methyltransferase 3(METTL3)in the pathogenesis of diabetic cataract.METHODS: We cultured SRA01/04 cells in low and high sugar media for 24h and measured changes in epithelial-mesenchymal transition(EMT)indicators(E-Cadherin, N-Cadherin, ZO-1 and α-SMA)using RT-qPCR and Western blot assays. Cell migration was also assessed using transwell and scratch assays. To investigate the expression level and localization of METTL3 in human lens anterior capsules tissues. Additionally, we used m6A dot blot assay to detect the m6A methylation level of cells cultured in low and high glucose media for 24h, and employed RT-qPCR and Western blot experiments to detect RNA and protein expression of METTL3 in cells. We then treated the cells with METTL3 inhibitor and measured changes in EMT markers by RT-qPCR and Western blot; m6A methylation level was detected by m6A dot blot test; cell migration was detected by Transwell. Finally, the expression of transforming growth factor-β(TGFβ1)in cultured cells was assessed by immunofluorescence staining and the expression levels of TGFβ1 and SNAIL in cells were determined using RT-qPCR and Western blot.RESULTS: Under high glucose conditions, the expression of EMT markers, METTL3, and m6A methylation levels were significantly increased in cells(P&#x003C;0.05). Furthermore, the migratory ability of cells was higher in high-sugar medium than in low-sugar medium. In human lens anterior capsules, METTL3 expression was higher in patients with diabetic cataract compared to those with age-related cataract. Importantly, treatment with the METTL3 inhibitor STM2457 inhibited EMT in cells, the expression of TGFβ1 and SNAIL, as well as m6A methylation levels in cells(all P&#x003C;0.05)compared to high-sugar + dimethyl sulfoxide(DMSO)group. Moreover, the migratory capacity of cells was reduced after the addition of STM2457 compared to the high-sugar + DMSO group.CONCLUSION:METTL3 promotes the EMT in human lens epithelial cells under high glucose conditions by activating the TGFβ1/SNAIL pathway, thus contributing to the development of diabetic cataracts.

Methyltransferase-like 3-mediated N6-methyladenosine methylation modification regulates the biological activity of vascular endothelial cells via the Notch pathway / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the role and mechanism of methyltransferase-like 3(METTL3)-mediated N6-methyladenosine(m6A)methylation modification in regulating biological activity of vascular endothelial cells in the pathogenesis of choroidal neovascularization.METHODS: Human umbilical vein endothelial cells(HUVEC)cultured in vitro were divided into the following groups: control group(normal culture), low density lipoprotein(LDL)group, fluorescence-labelled LDL(Dil-LDL)group, 12.5μg/mL and 25μg/mL oxidized LDL(ox-LDL)groups, 12.5μg/mL and 25μg/mL fluorescence-labelled ox-LDL(Dil-ox-LDL)groups, DMSO group, STM2457(METTL3 inhibitor)group, DAPT group; and monkey retina-choroidal endothelial cells(RF/6A)cultured in vitro were divided into control group, DMSO group, 12.5 μg/mL ox-LDL group, and DAPT group. Endocytosed lipoprotein level was examined through fluorescence microscopy. RNA m6A methylation level was detected through a dot blot assay. Protein and RNA levels of METTL3 or angiogenesis-related markers were measured through Western blot assays and real-time quantitative polymerase chain reaction(RT-qPCR), respectively. METTL3 expression and localization were investigated through immunofluorescence. Cell migratory and tube formation capacities were assessed through transwell migration and tube formation assays, respectively.RESULTS: Endocytosed lipoprotein levels in HUVECs exposed to Dil-LDL, 12.5μg/mL and 25μg/mL Dil-ox-LDL groups were significantly higher than those in the control group. 12.5μg/mL and 25μg/mL ox-LDL groups significantly increased m6A methylation(all P&#x003C;0.05), METTL3 protein expression(all P&#x003C;0.01), and cell migration and angiogenesis capacities(all P&#x003C;0.01). METTL3 mRNA level was significantly unregulated in the 12.5μg/mL ox-LDL group(P&#x003C;0.05). In comparison to the DMSO group, the addition of STM2457 caused significant decrease in m6A methylation level(P&#x003C;0.05), expression of VEGF and other angiogenesis-related markers(all P&#x003C;0.05), cell migration and angiogenesis capacities(all P&#x003C;0.01)and the expression of NICD(P&#x003C;0.05). However, there were no significant differences in METTL3 protein and mRNA levels(all P&#x003E;0.05). The expression of VEGF and NICD(all P&#x003C;0.05), as well as the ability of cell migration and angiogenesis of RF/6A, was all significantly decreased in the DAPT group compared to the DMSO group(all P&#x003C;0.01).CONCLUSION: METTL3-mediated m6A methylation modification promotes angiogenesis in vascular endothelial cells via the Notch signaling pathway in the pathogenesis of choroidal neovascularization.

RNA m6A modification affects tumorigenesis and development of hematological malignancies / 中华检验医学杂志

N6-Methyladenosine (m6A) is one of the most prevalent RNA modifications in mammals. The m6A modification is catalyzed by m6A writers or erasers and involved in various RNA metabolic processes with the recognition by m6A readers. Recently, emerging studies have shown m6A modification is pivotal in fundamental bioprocesses including cell homeostasis and oxidative stress, programmed cell death, cell metabolism, and immune regulation, and accounts for tumoral occurrence and development. To date, abnormal m6A levels and dysregulated related enzymes participate in tumorigenesis and chemoresistance among acute leukemias, chronic myeloid leukemia, multiple myeloma, lymphomas, thus influencing patient prognosis. The mechanisms of m6A modification are sophisticated and varied in different types of malignancies or subtypes. Screening appropriate patients to apply m6A-targeted inhibitors is instructive to the precise treatment of hematological malignancies.

Research progress of m 6A methylation modification in respiratory viruses replication and host immune response / 中华临床感染病杂志

N 6-methyladenosine (m 6A) modification is the most prevalent internal modification of eukaryotic mRNA and is dynamically regulated by a variety of m 6A modifying enzymes, including methylation transferases, demethylases and specific binding proteins. Respiratory viral infections have received much attention in recent years, and the process of virus replication and metabolism in host cells is regulated by m 6A. This article reviews the mechanism of m 6A-regulated enzymes, the roles of m 6A modifications in respiratory viruses replication and the host immune response to viruses, including adenovirus, influenza A virus, severe acute respiratory syndrome coronavirus 2, respiratory syncytial virus, and human metapneumovirus. It would provide a reference for exploring the regulatory role of viral episodic transcriptome modifications and antiviral targets or vaccine development.

The key role of RNA N 6-methyladenosine (m 6A) methylation in tumor radiotherapy and radiation damage repair / 中华放射医学与防护杂志

N 6-methyladenosine (m 6A) is the most abundant epigenetic modification in eukaryotic messenger RNA (mRNA), which could be catalyzed by m 6A methyltransferase (Writers), recognized by methylation recognition enzymes (Readers), and removed by demethylase (Erasers). RNA splicing, translation, and stability could be modulated by m 6A methylation modification. The m 6A methylation modification is involved in the biological regulation of a variety of important functional genes in cellular activities. Importantly, abnormal m 6A modification affects the occurrence, development, metastasis and recurrence of tumors. Ionizing radiation can affect the level of m 6A and m 6A methylation-related enzymes. Recently, m 6A methylation is reported to regulate the efficacy of tumor radiotherapy by affecting DNA damage and radiosensitivity of tumor cells. In addition, ionizing radiation can also affect the level of m 6A modification in normal cells to regulate the progress of radiation-induced injuries. This review summarizes the research progress on the roles of m 6A methylation in tumor radiosensitivity and radiation-induced injuries, with the aim of providing novel strategies for the development of clinical tumor radiosensitizers and radioprotective agents.

Methyltransferase like protein 14 and tumor / 国际肿瘤学杂志

N 6-methyladenosine (m 6A) modification, as the most prevalent epigenetic modification of RNA, plays a crucial role in the initiation and development of malignancies. Methyltransferase like protein 14 (METTL14) is a major methylase catalyzing m 6A modification and regulating biological processes such as RNA splicing, translation and degradation. Recent studies have demonstrated that METTL14 not only regulates the growth, invasion and metastasis of tumors through various molecular mechanisms, but also is closely correlated with the prognosis of tumor patients and clinical efficacy of anti-tumor therapies. In-depth understanding of the mechanism of METTL14 in breast, digestive system and urinary system tumors is helpful to provide new clinical markers and drug targets for the prevention and treatment of tumors based on m 6A modification.

Exploration and prospects of fat mass and obesity-associated in glioblastoma / 国际外科学杂志

Glioblastoma (GBM) is a common malignant neuroepithelial tumor of the central nervous system with rapid progression and high drug resistance. Fat mass and obesity associated (FTO), as the main demethylase in the modification process of N6-methyladenosine, is widely involved in GBM regulation, including tumor occurrence and development. It is also associated with the mutation of isocitrate dehydrogenase. The role of FTO in the aspects of biological function, glioblastoma stem cell sustaining and selfrenewing and chemotherapy resistance remained contentious. In this paper, FTO is preliminarily described through bioinformatics and current research, and the future research is prospected from the perspectives of energy metabolism, small molecule RNA regulation and post-translational modification.

N 6-methyladenosine-dependent pri-miR-17-92 mature activates AKT/mTOR pathway to promote endometrial cancer progression / 中华内分泌外科杂志

Objective:To explore the role of N 6-methyladenosine (m6A) and its regulator METTL3 in the non-coding RNA of endometrial cancer.Methods:The expression levels of m6A and METTL3 were quantified in 20 paired carcinoma and adjacent clinical tissue samples from patients at from Jul. 2016 to Dec. 2020. HEC-1-A cell lines were constructed with METTL3 overexpression and knockdown. Western blot was used to detect the phosphorylation levels of key molecules in METTL3 and Akt/mTOR. The quantitative detection of mRNA levels were used qRT-PCR. The binding level of m6A to its receptor DGCR8 was determined by RNA immunoprecipitation.Results:The results of the m6A RNA methylation quantification kit showed that m6A (1.0±0.15) vs (1.7±0.34) ( P<0.01) and METTL3 levels were elevated in endometrial cancer cells, and METTL3 (1.0±0.13) vs (2.5±0.45) ( P<0.05) levels were elevated in endometrial cancer cells. Western blot and qRT-PCR detection of miR-17-92 cell clusters overexpressing METTL3, METTL3 overexpression significantly increased m6A modification on pri-miR-17-92 ( P<0.05) . Phosphorylation levels of AKT/mTOR pathway-related proteins were upregulated. In addition, RIP test results indicated that the binding of DGCR8 to pri-miR-17-92 was significantly facilitated. Conclusion:METTL3 modification of m6A facilitates the processing of pri-miR-1792 into the miR-17-92 clusters via m6A/DGCR8-dependent mechanism, which in turn activated the AKT/mTOR pathway.

Expressions of m6A methyltransferases and their associations with microR-21 and transforming growth factor-β1 in kidney of rats exposed to cadmium / 环境与职业医学

Background Environmental pollutants can affect N6-methyladenosine (m6A) level in the body, but the change of m6A level in kidney after being exposed to cadmium (Cd) and the molecular mechanism of renal injury need to be further studied. Objective To analyze the associations of m6A modification and methyltransferases/demethylases with microRNA-21 (miR-21) and transforming growth factor- β1 (TGF - β1) in kidney of rats exposed to Cd. Methods Twenty-four SPF male SD rats were divided into 4 groups, with 6 rats in each group, and were exposed to Cd by subcutaneous injection of 2.0, 1.0, and 0.5 mg·kg−1 cadmium chloride (CdCl2) and equal volume of normal saline for 2 weeks, 7 d a week, respectively. The levels of N-acetyl-β-D-glucosidase (UNAG) and albumin (UALB) in urine, and the levels of m6A methylation and TGF-β1 in kidney were detected by enzyme-linked immunosorbent assay (ELISA). The level of blood urea nitrogen (BUN) was measured by urease method. The levels of renal oxidative stress indicators such as malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) were detected by total bile acid method, water-soluble tetrazolium asssay, and colorimetric method respectively. The relative levels of TGF-β1, methyltransferases, and demethylases in kidney were measured by reverse transcription-polymerase chain reaction. The expression of miR-21 in kidney was detected by fluorescent quantitative polymerase chain reaction. Results After 2 weeks of exposure to Cd, the body weights of rats in the 2.0 and 1.0 mg·kg−1 cadmium chloride groups decreased, and the ratio of kidney/body weight and the levels of BUN, UNAG, and TGF-β1 mRNA and protein increased in the 2.0 mg·kg−1 cadmium chloride group (P<0.05). The expression levels of m6A modification, methyltransferases METTL3, METTL14, Wilms’ tumor 1-associated protein (WTAP), and miR-21 were increased both in the 2.0 and 1.0 mg·kg−1 cadmium chloride groups, with significant differences compared with the control group (P<0.05). The results of correlation analysis showed that the m6A modification level was negatively correlated with SOD (r=−0.4489, P<0.05) and GSH-Px (r=−0.4874, P<0.05), METTL3 was negatively correlated with MDA (r=−0.5158, P<0.05), while there was a positive correlation between FTO and GSH-Px (r=0.4802, P<0.05). In addition, miR-21 was positively correlated with METTL3 (r=0.7491), METTL14 (r=0.6157), and WTAP (r=0.6660) (P<0.05), TGF-β1 was positively correlated with METTL3 (r=0.5025, P<0.05) but negatively correlated with FTO (r=−0.5634, P<0.05) . Conclusion Cd can induce m6A methylation and up-regulation of METTL3, METTL14, WTAP, and miR-21 expression levels in rat kidney tissues, indicating that m6A and miR-21 may be associated with Cd-induced renal fibrosis.

Changes of m6A modification in arsenic-induced oxidative stress of human embryonic lung fibroblasts / 环境与职业医学

Background Arsenic can be toxic to human by triggering oxidative stress, which is companied by epigenetic modifications. Objective To investigate the modification of N6-methyladenosine (m6A) in human embryonic lung fibroblasts (HELF) during oxidative stress induced by sodium arsenite (NaAsO2). Methods HELF cells were treated by designed concentrations of NaAsO2 (0, 2.5, 5, 10, and 20 μmol·L−1) for 48 h. Cell viability was detected by 3-(4,5-dimethylthia zol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfopheny)-2H-tetrazolium (MTS) method; the activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) as well as the content of malondialdehyde (MDA) were detected with corresponding kits; the level of m6A methylation in total RNA was detected by enzyme-linked immunosorbent assay; the mRNA expressions of m6A modified enzymes were detected by real-time fluorescence quantitative PCR, including methyltransferase-like 3 (METTL3), methyltransferase-like 14 (METTL14), Wilms' tumor 1-associated protein (WTAP), fat mass and obesity-associated protein (FTO), alkB family of Fe(II)/α-ketoglutarate-dependent dioxygenases 5 (ALKBH5), YTH domain containing protein 2 (YTHDC2), YTH domain family protein 2 (YTHDF2), and YTH domain family protein 3 (YTHDF3); the protein expressions of METTL3, FTO, YTHDC2, YTHDF3, and nuclear factor erythroid 2-related factor 2 (NRF2) were detected by Western blotting. The enrichment of m6A in NRF2 mRNA was detected by RNA methylated immunoprecipitation combined with real-time fluorescence quantitative PCR (MeRIP-qPCR). Results After the 0, 2.5, 5, 10, and 20 μmol·L−1 NaAsO2 treatment, the MTS results showed that compared with the control group, the cell viability of the 20 μmol·L−1 group decreased to 84% (P<0.05). The colorimetry results showed that compared with the control group, the activities of T-SOD in the 10 and 20 μmol·L−1 groups decreased (P<0.05); the activities of GSH-Px in the 2.5 and 10 μmol·L−1 groups decreased (P<0.05); the contents of MDA in the 10 and 20 μmol·L−1 groups increased. The results of enzyme-linked immunosorbent assay showed that the overall m6A methylation levels in the 0, 2.5, 5, 10, and 20 μmol·L−1 groups were (0.193 ± 0.023)%, (0.247 ± 0.021)%, (0.253 ± 0.006)%, (0.233 ± 0.006)%, and (0.262 ± 0.010)%, respectively, and compared with the control group, the m6A methylation levels in all the NaAsO2 treated groups increased (P<0.05). The real-time fluorescence quantitative PCR results showed that compared with the control group, the mRNA relative expression level of METTL3 decreased in the 2.5, 10, and 20 μmol·L−1 groups (P<0.05); the mRNA relative expression level of FTO decreased in the 20 μmol·L−1 group; the mRNA relative expression level of YTHDC2 increased in the 10 and 20 μmol·L−1 groups (P<0.05); the mRNA relative expression level of YTHDF3 increased in the 2.5, 10, and 20 μmol·L−1 groups (P<0.05). The Western blotting results showed that compared with the control group, the relative protein expression of METTL3 decreased in the 10 and 20 μmol·L−1 groups; the relative protein expression of FTO decreased in the 5 and 20 μmol·L−1 groups; the relative protein expression of YTHDC2 decreased in the 20 μmol·L−1 group (P<0.05); the relative nuclear protein expression of NRF2 decreased in the 10 and 20 μmol·L−1 groups (P<0.05). The MeRIP-qPCR results showed that m6A enrichment was significantly increased in the 20 μmol·L−1 NaAsO2 exposure group compared with the control group (P<0.05). After over-expression of FTO, the mRNA and protein relative expression levels of FTO and the relative expression level of nuclear protein of NRF2 in the FTO group were higher than those in the control group (P<0.05); the mRNA and protein relative expression levels of FTO in the NaAsO2 + FTO group and the nuclear protein expression level of NRF2 were higher than those in the NaAsO2 group (P<0.05). Conclusion In the process of oxidative stress induced by NaAsO2, m6A methylation level, m6A modified enzymes, m6A modification of NRF2 mRNA, and NRF2 expression could change in HELF cells.

Changes of mRNA N6-methyladenosine methylation in blood of patients with Alzheimer's disease / 中华行为医学与脑科学杂志

Objective:To explore the changes of mRNA N6-methyladenosine methylation level and methyltransferase-like 3 (METTL3) and demethylase fat mass and obesity-associated (FTO) in the blood of patients with Alzheimer's disease (AD) compared with normal controls.Methods:From January 2020 to June 2021, totally 40 AD patients treated in the outpatient and inpatient department of Neurology of the Affiliated Hospital of Jining Medical University were selected as the patient group, and 40 healthy volunteers as the control group. The blood samples were collected to extract plasma and peripheral blood mononuclear cells for enzyme-linked immunosorbent assay (ELISA), Western blot (WB), quantitative real-time PCR (qPCR) and m6A methylation quantification experiments respectively to detect the methylation levels of METTL3, FTO and m6A. The data were analyzed by SPSS 23.0 statistical software for t-test. Results:The plasma concentrations of METTL3 and FTO protein in AD group were lower than those in control group (METTL3: (22.33±3.01)ng/mL, (25.63±1.70)ng/mL, t=6.055, P<0.01; FTO: (63.51±4.95)pg/mL, (69.60±4.60)pg/mL, ( t=5.704, P<0.01). The band gray values of METTL3 and FTO protein in blood cells in AD group were lower than those in control group (METTL3: 0.399 5±0.028 7, 0.676 6±0.053 3, t=7.935, P=0.001; FTO: 0.439 4±0.017 8, 0.782 6±0.087 6, t=6.652, P=0.003). The expression levels of METTL3 and FTO in blood cell RNA in AD group were lower than those in control group (METTL3: 0.387 8±0.020 3, 1.010 0±0.177 0, t=6.041, P=0.004; FTO: 0.442 8±0.037 1, 1.003 0±0.090 4, t=9.931, P=0.001). The levels of m6A in blood cell RNA in AD group were lower than those in control group((0.000 571±0.000 167)%, (0.002 514±0.001 284)%, t=6.041, P=0.004). Conclusion:The levels of METL3, FTO and m6A methylation are down-regulated in the plasma and peripheral blood mononuclear cells of patients with AD, indicating that there is a certain association between mRNA N6-methyladenosine methylation and AD.

The role of the fat mass and obesity-associated protein in ischemia-reperfusion injury of human renal tubular epithelial cells / 中华实用儿科临床杂志

Objective:To explore the role of the fat mass and obesity-associated protein (FTO) in human renal tubular epithelial cells (HK-2) suffering ischemia-reperfusion injury (IRI).Methods:The in vitro IRI mo-del was established in HK-2 cells by induction with antimycin A, A23187 and 2-deoxy-D-glucose.The cells were divided into control group and ischemia-reperfusion group (I/R group). The mRNA and protein expressions of FTO, B-cell lymphoma / leukemia 2(Bcl-2)-associated X(Bax), Bcl-2 and cleaved cysteinyl aspartate specific proteinase(cleaved Caspase-3) in HK-2 cells before and after IRI were detected by real-time fluorescent quantitative PCR(qPCR) and Western blot, respectively.Cell apoptosis was measured using flow cytometry.The level ofe N 6-methy-ladenosine (m 6A) RNA was detected by colorimetry. Results:(1) The mRNA expressions of FTO (0.15±0.05 vs.1.00±0.23) and Bcl-2 (0.14±0.07 vs.1.02±0.25) in I/R group were significantly lower than those in control group; While those of Bax (3.10±0.35 vs.1.00±0.13) and cleaved Caspase-3 (4.21±0.56 vs.1.00±0.09) were significantly higher ( t=6.28, 5.84, -9.83, and -9.84, respectively, all P<0.01). (2) The protein expressions of FTO (0.69±0.14 vs.1.37±0.02) and Bcl-2 (0.50±0.12 vs.1.25±0.21) were significantly lower in I/R group than those of control group; While those of Bax (1.04±0.08 vs.0.57±0.06) and cleaved Caspase-3 (0.99±0.05 vs.0.36±0.07) were significantly higher ( t=8.10, 5.49, -8.22, and -12.09, respectively, all P<0.05). (3) Compared with the control group, the apoptosis rate of HK-2 cells in I/R group was significantly higher [(61.70±1.01)% vs.(0.16±0.10)%, t=63.80, P<0.01]. (4) Compared with the control group, the percentage of m 6A modification level in total RNA in I/R group was significantly higher [(3.13±0.21)% vs.(1.10±0.26)%, t=-10.61, P<0.01]. Conclusions:FTO-mediated RNA m 6A modification may affect renal IRI by regulating the apoptosis of HK-2 cells.

Effects of N6-methyladenosine-induced LncRNA PVT1 targeting MYC on the stemness of ketamine-treated breast cancer cells / 中华内分泌外科杂志

Objective:To investigate the effect of ketamine on dryness maintenance of breast cancer (BC) cells by regulating LncRNA PVT1/MYC axis.Methods:BC cell line MCF-7 was treated with different concentration of ketamine (0, 5, 10 or 20 g/ml) or treated with 20g/ml ketamine for different periods (0, 24, 48 or 72h) . Furthermore, the expression of METTL3, PVT1 and MYC in MCF-7 cells was interfered and MCF-7 cells were divided into different groups.Western blot was used to detect the expression levels of stem cell characteristic related molecules (OCT4 and SOX2) . The expression level of PVT1/MYC in each group was detected by qRT-PCR. MeRIP analysis was used to detect THE m6A methylation level of PVT1.Results:Ketamine treatment significantly reduced the number of BC globules and inhibited the protein expression of OCT4 and SOX2 in a dose-and time-dependent manner (all P<0.05) . Ketamine regulated m6A level of METTL3-mediated PVT1. Compared with ketamine+pcDNA3.1 group (207±11) , the number of globules formed in ketamine+PVT1 group (311±15) was significantly increased ( t=12.06, P<0.001) , and the protein expression levels of OCT4 and SOX2 were increased ( t=9.68, P<0.001; t=11.50, P<0.001) . MYC was a downstream regulatory gene of PVT1. Compared with ketamine+PVT1+ Si-NC group, ketamine+PVT1+si-MYC group significantly reduced the number of spheroid formation ( t=0.54, P=0.005) and the expression levels of OCT4 and SOX2 proteins ( t=5.98, P=0.004) ( t=7.33, P=0.002) . Conclusion:Ketamine mediates the expression of PVT1 and its downstream gene MYC by inhibiting THE m6A level of PVT1, thus inhibiting the stem cell-like characteristics of BC cells.

Characteristics of N6-methyladenosine modification patterns in t(8;21) acute myeloid leukemia / 南方医科大学学报

OBJECTIVE@#To investigate the relationship between AML1-ETO (AE) fusion gene and intracellular N6-methyladenosine (m6A) modification pattern in t(8;21) acute myeloid leukemia (AML).@*METHODS@#RNA m6A sequencing was performed in SKNO-1 and AE knockdown SKNO-1 (SKNO-1 siAE) cells using RNA-protein co-immunoprecipitation and high-throughput sequencing (methylated RNA immunoprecipitation sequencing, MeRIP-Seq) to analyze the changes in m6A modification of the entire transcriptome. Transcriptome sequencing (RNA-seq) was performed using high-throughput sequencing. The differentially modified mRNAs were further functionally annotated by Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The changes in m6A-related enzyme expressions were detected using real-time PCR.@*RESULTS@#A total of 26 441 genes were identified in AE knockdown AML cells and AE-expressing cells, containing 72 036 m6A peaks. AE knockdown caused a reduction of the number of intracellular m6A peaks from 37 042 to 34 994, among which 1278 m6A peaks were significantly elevated and 1225 were significantly decreased; 1316 genes with newly emerged m6A modification were detected and 1830 genes lost m6A modification after AE knockdown. The differential peaks were mainly enriched in pathways involving cancer and human T-lymphocytic leukemia virus I. RNA-seq results showed that 2483 genes were up-regulated and 3913 genes were down-regulated after AE knockdown. The combined analysis of MeRIP-Seq and RNA-Seq results revealed relatively high expression levels of m6A-modified genes as compared with the genes without m6A modification (SKNO-1: 0.6116±1.263 vs 2.010±1.655, P < 0.0001; SKNO-1 siAE: 0.5528±1.257 vs 2.067±1.686, P < 0.0001). The m6A modified genes located in the 3'UTR or 5 'UTR had significantly higher expression levels than those located in exonic regions (SKNO-1: 2.177± 1.633 vs 1.333 ± 1.470 vs 2.449 ± 1.651, P < 0.0001; SKNO-1 siAE: 2.304 ± 1.671 vs 1.336 ± 1.522 vs 2.394 ± 1.649, P < 0.05). Analysis of RNA-seq data identified 3 m6A-related enzymes that showed significantly elevated mRNA expression after AE knockdown, namely WTAP, METTL14, and ALKBH5 (P < 0.05), but the results of real-time PCR showed that the expressions of WTAP and ALKBH5 were significantly increased while the expression of METTL14 was lowered after AE knockdown (P < 0.05).@*CONCLUSION@#AE knockdown results in differential expressions of m6A-associated enzymes, suggesting that the AE fusion gene regulates the expression of one or more m6A-associated enzymes to control cellular methylation levels.