Folate regulates RNA mC modification and translation in neural stem cells.

Background: Folate is an essential B-group vitamin and a key methyl donor with important biological functions including DNA methylation regulation. Normal neurodevelopment and physiology are sensitive to the cellular folate levels. Either deficiency or excess of folate may lead to neurological disorders. Recently, folate has been linked to tRNA cytosine-5 methylation (mC) and translation in mammalian mitochondria. However, the influence of folate intake on neuronal mRNA mC modification and translation remains largely unknown. Here, we provide transcriptome-wide landscapes of mC modification in poly(A)-enriched RNAs together with mRNA transcription and translation profiles for mouse neural stem cells (NSCs) cultured in three different concentrations of folate.

Results: NSCs cultured in three different concentrations of folate showed distinct mRNA methylation profiles. Despite uncovering only a few differentially expressed genes, hundreds of differentially translated genes were identified in NSCs with folate deficiency or supplementation. The differentially translated genes induced by low folate are associated with cytoplasmic translation and mitochondrial function, while the differentially translated genes induced by high folate are associated with increased neural stem cell proliferation. Interestingly, compared to total mRNAs, polysome mRNAs contained high levels of mC. Furthermore, an integrative analysis indicated a transcript-specific relationship between RNA mC methylation and mRNA translation efficiency.

Conclusions: Altogether, our study reports a transcriptome-wide influence of folate on mRNA mC methylation and translation in NSCs and reveals a potential link between mRNA mC methylation and mRNA translation.