METTL3 Reduces Oxidative Stress-induced Apoptosis in Presbycusis by Regulating the N6-methyladenosine Level of SIRT1 mRNA

IGF2BP3 stabilizes SESN1 mRNA to mitigate oxidized low-density lipoprotein-induced oxidative stress and endothelial dysfunction in human umbilical vein endothelial cells by activating Nrf2 signaling

Atherosclerosis (AS) represents a prevalent initiating factor for cardiovascular events. Insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) is an oncofetal RNA-binding protein that participates in cardiovascular diseases. This work aimed to elaborate the effects of IGF2BP3 on AS and the probable mechanism by using an oxidized low-density lipoprotein (ox-LDL)-induced human umbilical vein endothelial cells (HUVECs) model. Results indicated that IGF2BP3 expression was declined in the blood of AS patients and ox-LDL-induced HUVECs. IGF2BP3 elevation alleviated ox-LDL-provoked viability loss, apoptosis, oxidative DNA damage and endothelial dysfunction in HUVECs. Moreover, IGF2BP3 bound SESN1 and stabilized SESN1 mRNA. Furthermore, SESN1 interference reversed the impacts of IGF2BP3 overexpression on the apoptosis, oxidative DNA damage and endothelial dysfunction of ox-LDL-challenged HUVECs. Additionally, the activation of Nrf2 signaling mediated by IGF2BP3 up-regulation in ox-LDL-treated HUVECs was blocked by SESN1 absence. Collectively, SESN1 stabilized by IGF2BP3 might protect against AS by activating Nrf2 signaling.

Geniposide reduced oxidative stress-induced apoptosis in HK-2 cell through PI3K/AKT3/FOXO1 by m6A modification

Exogenous hydrogen peroxide (H2O2) may generate excessive oxidative stress, inducing renal cell apoptosis related with kidney dysfunction. Geniposide (GP) belongs to the iridoid compound with anti-inflammatory, antioxidant and anti-apoptotic effects. This study aimed to observe the intervention effect of GP on H2O2-induced apoptosis in human kidney-2 (HK-2) cells and to explore its potential mechanism in relation to N6-methyladenosine (m6A) RNA methylation. Cell viability, apotosis rate and cell cycle were tested separately after different treatments. The mRNA and protein levels of m6A related enzymes and phosphoinositide 3-kinase (PI3K)/a serine/threonine-specific protein kinase 3 (AKT3)/forkhead boxo 1 (FOXO1) and superoxide dismutase 2 (SOD2) were detected by reverse transcription-quantitative real-time PCR (RT-qPCR) and Western blot. The whole m6A methyltransferase activity and the m6A content were measured by ELISA-like colorimetric methods. The changes of m6A methylation levels of PI3K/AKT3/FOXO1 and SOD2 were determined by methylated RNA immunoprecipitation (MeRIP)-qPCR. Multiple comparisons were performed by ANOVA with Turkey's post hoc test. Exposed to 400 μmol/L H2O2, cells were arrested in G1 phase and the apoptosis rate increased, which were significantly alleviated by GP. Compared with the H2O2 apoptosis group, both the whole m6A RNA methyltransferase activity and the m6A contents were increased due to GP intervention. Besides, the SOD2 protein was increased, while PI3K and FOXO1 decreased. The m6A methylation level of AKT3 was negatively correlated with its protein level. Taken together, GP affects the global m6A methylation microenvironment and regulates the expression of PI3K/AKT3/FOXO1 signaling pathway via m6A modification, alleviating cell cycle arrest and apoptosis caused by oxidative stress in HK-2 cells with a good application prospect.

Dietary selenomethionine reduced oxidative stress by resisting METTL3-mediated m6A methylation level of Nrf2 to ameliorate LPS-induced liver necroptosis in laying hens

Selenomethionine (SeMet) as the main form of daily dietary selenium, occupies essential roles in providing antioxidant and anti-inflammatory properties, which alleviates inflammatory liver damage. N6-methyladenosine (m6A) is one of the most prevalent and abundant internal transcriptional modifications that regulate gene expression. To investigate the protective mechanism of SeMet on liver injury and the regulatory effect of m6A methylation modification, we established the model by supplementing dietary SeMet, and LPS as stimulus in laying hens. LMH cells were intervened with SeMet (0.075 µM) and/or LPS (60 µg/mL). Subsequently, histopathology and ultrastructure of liver were observed. Western Blot, qRT-PCR, colorimetry, MeRIP-qPCR, fluorescent probe staining and AO/EB were used to detect total m6A methylation level, m6A methylation level of Nrf2, ROS, inflammatory and necroptosis factors. Studies showed that SeMet suppressed LPS-induced upregulation of total m6A methylation levels and METTL3 expression. Interestingly, SeMet reduced the m6A methylation level of Nrf2, activated antioxidant pathways and alleviated oxidative stress. LMH cells were transfected with 50 µm siMETTL3. SeMet/SiMETTL3 reversed the LPS-induced reduction in Nrf2 mRNA stability, slowed down its degradation rate. Moreover, LPS induced oxidative stress, led to necroptosis and activated NF-κB to promote the expression of inflammatory factors. SeMet/SiMETTL3 alleviated LPS-induced necroptosis and inflammation. Altogether, SeMet enhanced antioxidant and anti-inflammatory capacity by reducing METTL3-mediated m6A methylation levels of Nrf2, ultimately alleviating liver damage. Our findings provided new insights and therapeutic target for the practical application of dietary SeMet in the treatment and prevention of liver inflammation, and supplied a reference for comparative medicine.

Comprehensive Transcriptomic Profiling of m6A Modification in Age-Related Hearing Loss

Age-related hearing loss (ARHL), also known as presbycusis, is one of the most common neurodegenerative disorders in elderly individuals and has a prevalence of approximately 70-80% among individuals aged 65 and older. As ARHL is an intricate and multifactorial disease, the exact pathogenesis of ARHL is not fully understood. There is evidence that transcriptional dysregulation mediated by epigenetic modifications is widespread in ARHL. However, the potential role of N6-methyladenosine (m6A) modification, as a crucial component of epigenetics, in ARHL progression remains unclear. In this study, we confirmed that the downregulation of m6A modification in cochlear tissues is related to ARHL and found that the expression of the m6A methylation regulators Wilms tumour suppressor-1-associated protein (WTAP), methyltransferase-like 3 (METTL3), ALKB homologous protein 5 (ALKBH5) and fat mass and obesity-associated protein (FTO) is decreased significantly at the mRNA and protein levels in ARHL mice. Then, we used methylated RNA immunoprecipitation sequencing (MeRIP-Seq) and RNA sequencing (RNA-Seq) to identify the differentially m6A-methylated genes in the cochlear tissues of ARHL mice. A total of 3438 genes with differential m6A methylation were identified, of which 1332 genes were m6A-hypermethylated and 2106 genes were m6A-hypomethylated in the ARHL group compared to the control group according to MeRIP-seq. Further joint analysis of RNA-Seq and MeRIP-Seq data showed that 262 genes had significant differences in both mRNA expression and m6A methylation. GO and KEGG analyses indicated that 262 unique genes were enriched mainly in the PI3K-AKT signalling pathway. In conclusion, the results of this study reveal differential m6A methylation patterns in the cochlear tissues of ARHL mice, providing a theoretical basis for further study of the pathogenesis of ARHL and potential therapeutic strategies.