Reduced H3K27me3 suppresses Wnt/β-catenin signaling by S-adenosylmethionine deficiency in neural tube development

Abstract S-adenosylmethionine (SAM) as a major methyl donor play a key role in methylation modification in vivo, and its disorder was closely related to neural tube defects (NTDs). However, the underlying mechanism between SAM deficiency and NTDs remained unclear. Here, we investigated the association between histone methylation modification and Wnt/β-catenin signaling pathway in NTDs induced by SAM deficiency. The levels of SAM and SAH were determined by enzyme linked immunosorbent assay (ELISA). The expressions of H3K27me3 and Wnt/β-catenin signaling pathway specific markers were demonstrated by western blotting, reverse transcription, and quantitative PCR (RT-qPCR) and immunofluorescence in ethionine induced E11.5 mouse NTDs and NSCs models. The results showed that the incidence rate of NTDs induced by ethionine were 46.2%, post treatment of ethionine combined with SAM, the incidence rate of NTDs was reduced to 26.2%. The level of SAM was significantly decreased (P<0.05) and a reduction in the SAM/SAH ratio was observed. The SAM depletion caused the reduction of both H3K27me3 modifications and UTX activity, and inhibited the marker proteins (β-catenin, TCF-4, Axin-2, p-GSK-3β, CyclinD1, and C-myc) in Wnt/β-catenin signaling pathway (P<0.05). The differentiations of neural stem cells (NSCs) into neurons and oligodendrocytes were inhibited under SAM deficiency (P<0.05). These results indicated that the depletion of SAM led to reduced H3K27me3 modifications, prevented the activation of Wnt/β-catenin signaling pathway and NSCs differentiation, which provided an understanding of the novel function of epigenetic regulation in NTDs.