Project description:Liver-specific deficiency of Mettl3 causes liver injury. By performing RNA sequencing (RNA-seq) analysis on the Mettl3-deficient versus control livers, we identified the potential target genes that were closely associated with the liver phenotype in liver-specific Mettl3 knockout mice. RNA-seq analysis revealed extensive metabolic reprogramming in Mettl3-deficient livers. These results demonstrated that Mettl3 coordinates metabolic homeostasis and functional maturation during postnatal liver development.
Project description:The N6-methyladenosine (m6A) mRNA modification and the mitochondrial respiratory chain (MRC) hold paramount importance in the advancement of MASLD. This study thoroughly investigates the relationship and impact of m6A mRNA modification and mitochondrial function in the progression of MASLD. Here we report that the mRNA and protein levels of mitochondrial respiratory chain (MRC) subunits showed inconsistent trends in vivo experiments. Abnormal m6A modification and mitochondrial dysfunction in MASLD were attributed to the upregulation of methyltransferase like 3 (Mettl3) and the downregulation of YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) induced by high-fat foods. Mettl3 promoted the MRC's function. However, knockout of the reader protein YTHDF1, which plays a crucial role in the m6A modification process, counteracted the effect of Mettl3 and suppressed MRC. In MASLD, damage to the MRC may be regulated by the Mettl3-m6A-YTHDF1 complex axis, especially by the role of YTHDF1. Our research has offered a novel perspective on the involvement of m6A mRNA methylation in the pathogenesis of MASLD.
Project description:N6-methyladenosine (m6A) RNA methylation is the most abundant modification on mRNAs and plays important roles in various biological processes. The formation of m6A is catalyzed by a methyltransferase complex including methyltransferase like 3 (METTL3) as a key factor. However, the in vivo functions of METTL3 and m6A modification in mammalian development remain unclear. Here we show that specific inactivation of Mettl3 in mouse nervous system causes severe developmental defects in the brain. Mettl3 conditional knockout mice manifest cerebellar hypoplasia caused by drastically enhanced apoptosis of new born cerebellar granule cells (CGCs) in the external granular layer (EGL). METTL3 depletion induced loss of m6A modification causes extended RNA half-lives and aberrant splicing events, consequently leading to dysregulation of transcriptome-wide gene expression and premature CGC death. Our findings reveal a critical role of METTL3-mediated m6A in regulating the development of mammalian cerebellum.
Project description:To investigate the role of METTL3-mediated m6A modification, we performed m6A-sequencing to map the m6A modification in control or METTL3 knockdown BGC823 cells.
Project description:Epigenetic changes present in many physiological and pathological processes. The N6-methyladenosine (m6A) modification is the most common modification in eukaryotic mRNA. However, the role of m6A modification in diabetic nephropathy (DN) is still elusive. Here, the level of m6A modification was significantly upregulated in podocytes stimulated by high glucose (HG), which was caused by elevated levels of METTL3. The results were consistent in the streptozotocin (STZ)-induced experimental model of type 1 diabetes and db/db type 2 diabetes mice. Knocking out METTL3 significantly reduced the inflammation and apoptosis of HG-stimulated podocytes, while its overexpression significantly aggravated these responses. More importantly, silencing METTL3 both in type 1 and type 2 diabetic mice in vivo significantly reduced urinary albumin excretion and histopathological injury. Mechanistically, METTL3 modulated Notch signaling via the m6A modification of its target gene, TIMP2, and exerted pro-inflammatory and pro-apoptotic effects. Moreover, METTL3 enhanced the stability of TIMP2 in an insulin-like growth factor 2 mRNA binding protein 2 (IGF2BP2)-dependent manner. In summary, this study suggested that METTL3-mediated m6A modification is an important mechanism of podocyte injury in DN. Targeting m6A through the writer enzyme METTL3 is a potential approach for the treatment of DN.
Project description:Here we determine the map of RNA methylation (m6A) in mouse embrionic stem cells, and Mettl3 knock out cells Examination of m6A modification sites on the transcriptome of mouse Embryonic stem cells and Embryonic Mettl3 knock out cells, using a m6A specific antibody.
Project description:Esophageal cancer is a lethal malignancy with high mortality rate, while the molecular mechanisms underlying esophageal cancer pathogenesis are stillis poorly understood. Here we found that the N6-methyladenosine (m6A) methyltransferase METTL3 is significantly up-regulated in esophageal squamous cell carcinoma (ESCC) and associated with poor patient prognosis. Depletion of METTL3 results in decreased ESCC growth and progression in vitro and in vivo. We further established ESCC initiation and progression models using Mettl3 conditional knockout mouse and revealed that Mettl3 mediated m6A modification is essential for promotes ESCC initiation and progression in vivo. Moreover, using METTL3 overexpression ESCC cell model and Mettl3 conditional knockin mouse model, we demonstrated the critical function of Mettl3 in promoting in vivo ESCC tumorigenesis in vitro and in vivo. Mechanistically, Mettl3 catalyzed m6A modification promotes NOTCH1 expression and the activation of Notch signaling pathway. Forced activation of Notch signaling pathway successfully rescues the growth, migration and invasion capacities of METTL3 depleted ESCC cells. Our data uncovered important mechanistical insights underlying ESCC tumorigenesis and provided molecular basis for the development of novel strategies for ESCC diagnosis and treatment.
Project description:M6A modification plays a vital role in gestational diabetes mellitus (GDM) progression. However, the role of METTL3 and differential m6A-modified circRNAs in GDM stay to be investigated. Placental tissue samples from GDM patients and normal controls (NC) were collected to measure changes in m6A modification levels. MeRIP-seq on placental tissue was performed to detect differential m6A-modified circRNAs.High glucose (HG)-treated JEG3 cells were used to establish the GDM cell model. Differentially expressed circRNAs levels in GDM and NC groups was measured by qRT-PCR. We knocked down METTL3 to study its function. Additionally, we conducted functional recovery experiments. Dot blot assay was utilized to assess changes in m6A levels. MeRIP-qPCR was performed to evaluate the effect of knocking down METTL3 on m6A modification of hsa_circ_0072380 in JEG3 cells. Compared with NC group, GDM group exhibited increased levels of m6A modification and METTL3 expression. Differences in m6A modification of circRNAs exist between the GDM and NC groups. Hsa_circ_0000994, hsa_circ_0058733, and hsa_circ_0072380 were significantly down-regulated in GDM group while hsa_circ_0036376, hsa_circ_0000471, and hsa_circ_0001173 showed no significant differences between two groups. HG treatment promoted METTL3 expression and m6A level of JEG3 cells, and inhibited cell proliferation, migration, and invasion abilities. Knocking down METTL3 reversed these effects. After HG treatment, hsa_circ_0072380 was significantly down-regulated. Knocking down METTL3 led to up-regulation of hsa_circ_0072380, while knocking down hsa_circ_0072380 restored the function of SiMETTL3. Additionally, knocking down METTL3 significantly reduced m6A modification of hsa_circ_0072380. METTL3 mediated m6A modification of hsa_circ_0072380 to regulate GDM progression.