Previous studies have shown that Ogt-mediated O-GlcNAcylation is essential for neuronal development and function. However, the function of O-GlcNAc transferase (Ogt) and O-GlcNAcylation in astrocytes remains largely unknown. Here we show that Ogt deficiency induces inflammatory activation of astrocytes in vivo and in vitro, and impairs cognitive function of mice. The restoration of O-GlcNAcylation via GlcNAc supplementation inhibits the activation of astrocytes, inflammation and improves the impaired cognitive function of Ogt deficient mice. Mechanistically, Ogt interacts with NF-κB p65 and catalyzes the O-GlcNAcylation of NF-κB p65 in astrocytes. Ogt deficiency induces the activation of NF-κB signaling pathway by promoting Gsk3β binding. Moreover, Ogt depletion induces the activation of astrocytes derived from human induced pluripotent stem cells. The restoration of O-GlcNAcylation inhibits the activation of astrocytes, inflammation and reduces Aβ plaque of AD mice in vitro and in vivo. Collectively, our study reveals a critical function of Ogt-mediated O-GlcNAcylation in astrocytes through regulating NF-κB signaling pathway.

Nicotinamide adenine dinucleotide hydrate (NAD+) acts as the essential component of the tricarboxylic citric acid (TCA) cycle and has important functions in diverse biological processes. However, the roles of NAD+ in regulating adult neural stem/progenitor cells (aNSPCs) remain largely unknown. Here, we show that NAD+ exposure leads to the reduced proliferation and neuronal differentiation of aNSPCs and induces the apoptosis of aNSPCs. In addition, NAD+ exposure inhibits the morphological development of neurons. Mechanistically, RNA sequencing revealed that the transcriptome of aNSPCs is altered by NAD+ exposure. NAD+ exposure significantly decreases the expression of multiple genes related to ATP metabolism and the PI3k-Akt signaling pathway. Collectively, our findings provide some insights into the roles and mechanisms in which NAD+ regulates aNSPCs and neuronal development.

In neuronal system, epigenetic modifications are essential for neuronal development, the fate determination of neural stem cells and neuronal function. The dysfunction of epigenetic regulation is closely related to occurrence and development of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease. Abnormally elevated DNA methylation inhibits the expression of some DNA repair-related genes and affects the progression of Huntington's disease. In the brain of Alzheimer's disease patients, the levels of H3K27ac and H3K9ac histone modifications increased. In addition, the alteration of RNA methylation in animal models of Alzheimer's disease and Parkinson's disease showed discrepancy trends. Therefore, epigenetic modifications may serve as potential therapeutic targets for neurodegenerative diseases. Here, we summarize the recent progress of the roles of epigenetic modifications in neurodegenerative diseases.

Background N6-methyladenosine (m⁶A) is one of the common modifications of transcripts that is regulated by related proteins including writers, readers and erasers. Abnormal m⁶A modification plays an important role in the process of tumor development. Current approaches for tumor m⁶A RNA methylation, based on sequencing data from public databases, focus on the comparison of m⁶A modification regulator expression by RNA-seq data. Results We obtained MeRIP-seq and corresponding RNA-seq data from GEO database to compare and analyze the distributional characteristics of m⁶A in different types of tumor samples, the differences in m⁶A modification enrichment, and the regulatory role in gene transcriptional expression level. We found that the enrichment of m⁶A modification was enhanced in IMPA and GBM tumor samples, but was decreased in METTL3 knockdown tumor cells. Combined with clinical data from the TCGA database, we found that the high expression of DUSP7 significantly affected the overall survival of AML patients and was involved in tumor development through the PIK3R2 protein and MAPK signaling pathways. Conclusion Abnormal m⁶A modification enrichment in tumor samples leads to dysregulation in the expression of cancer-related genes.