Single-base resolution of mouse offspring brain methylome reveals epigenome modifications caused by gestational folic acid

Abstract

Background: Epigenetic modifications, such as cytosine methylation in CpG-rich regions, regulate multiple functions in mammalian development. Maternal nutrients affecting one-carbon metabolism during gestation can exert long-term effects on the health of the progeny. Using C57BL/6 J mice, we investigated whether the amount of ingested maternal folic acid (FA) during gestation impacted DNA methylation in the offspring's cerebral hemispheres. Reduced representation bisulfite sequencing at single-base resolution was performed to analyze genome-wide DNA methylation profiles.

Results: We identified widespread differences in the methylation patterns of CpG and non-CpG sites of key developmental genes, including imprinted and candidate autism susceptibility genes (P <0.05). Such differential methylation of the CpG and non-CpG sites may use different mechanisms to alter gene expressions. Quantitative real time reverse transcription-polymerase chain reaction confirmed altered expression of several genes.

Conclusions: These finding demonstrate that high maternal FA during gestation induces substantial alteration in methylation pattern and gene expression of several genes in the cerebral hemispheres of the offspring, and such changes may influence the overall development. Our findings provide a foundation for future studies to explore the influence of gestational FA on genetic/epigenetic susceptibility to altered development and disease in offspring.

Figure 1

Distribution of differentially methylated sites in CpG island sequences. (a) Male low maternal folic acid (LMFA) versus high maternal folic acid (HMFA). (b) Female LMFA versus HMFA.

Figure 2

Relative expression of the genes that exhibited hypermethylation (a, b) and hypomethylation (c, d). The results were normalized to Hprt transcript expression and were expressed as relative values in comparison with corresponding transcripts from low maternal folic acid (LMFA). Results represent mean ± standard deviation (SD); asterisks denote statistically significant change (*P <0.05, **P <0.01, ***P <0.001).

Figure 3

Distribution of differentially methylated sites in non CpG (CHG/CHH) sites. (a) Male low maternal folic acid (LMFA) versus high maternal folic acid (HMFA). (b) Female LMFA versus HMFA.