Reduced H3K27me3 Suppresses Wnt/β-catenin Signaling by S-adenosylmethionine Deficiency in Neural Tube Development

Abstract

Background: S-adenosylmethionine as a major methyl donor play a key role in methylation modification in vivo, and its disorder was closely related to neural tube defects. However, the underlying mechanism between SAM deficiency and NTDs remained unclear.Methods: 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. The expressions of H3K27me3 and Wnt/β-catenin signaling pathway specific markers were demonstrated by western blotting, reverse transcription, and quantitative PCR and immunofluorescence in ethionine induced E11.5 mouse NTDs and NSCs models. Results: we found 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 into neurons and oligodendrocytes were inhibited under SAM deficiency (P<0.05).Conclusions: 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.