Folic acid regulates neural mRNA m6A epitranscriptome via one-carbon metabolism in Drosophila and mammals

Folic acid is one of the B vitamins and is involved into neural function and brain development. Increasing evidence showed that folic acid can regulate neural gene function through DNA modification, while regulatory roles of folic acid in RNA modification remain largely unknown. In this study, we investigated the role of folic acid in regulating neural mRNA m6A epitranscriptome in Drosophila and mammals. We found that the folate treatment induced a significant increase in mRNA m6A levels compared to the control group in Drosophila and S2 cells. MeRIP-seq analysis indicated that carbon metabolism pathway and neural-related pathways were mainly affected. Subsequently, we migrated our validation experiments to human cells, our results showed that folate also affected mRNA m6A modification through one-carbon metabolic pathway in human cells, especially in neuronal cells. We also validated the effect of folic acid on mRNA methylation in mice, the results showed that folic acid treatment can significantly increase the expression of m6A-related proteins (Mettl3, Mettl14, FTO) and neural mRNA m6A methylation levels in mice brain. Moreover, we found that folic-acid producing Lactobacillus plantarum can significantly affects the m6A modification of mRNA in the host. In conclusion, we demonstrated that folic acid can participate in mRNA m6A modification through one-carbon metabolic pathway in Drosophila and mammals, and found that it has a significant effect on neural-related genes and pathways. Overall design: In this study, we investigated the regulatory role of folic acid in Drosophila and mammalian neural mRNA m6A table transcriptome. The experimental groups were folate-treated Drosophila and folate-treated S2 cells. meRIP-seq analysis showed that carbon metabolic pathways and neural-related pathways were mainly affected. Subsequently, we knocked down the screened gene DHFR, and the experimental groups were DHFR knockdown cells. We also verified the effect of folic acid on mRNA methylation in mice, and the experimental group was folic acid-treated mice. In addition, we found that folic acid-producing Lactobacillus plantarum significantly affected the m6A modification of mRNA in the host, and the experimental group was Drosophila treated with Lactobacillus plantarum.