Effect of imbalance in folate and vitamin B12 in maternal/parental diet on global methylation and regulatory miRNAs

Aatish Mahajan,Jyotdeep Kaur,Palani Selvam Mohanraj,Rashmi Bagga,Shilpa Thakur,Divika Sapehia

doi:10.1038/s41598-019-54070-9

Aatish Mahajan, Jyotdeep Kaur + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-54070-9

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Abstract

DNA methylation, a central component of the epigenetic network is altered in response to nutritional influences. In one-carbon cycle, folate acts as a one-carbon carrier and vitamin B12 acts as co-factor for the enzyme methionine synthase. Both folate and vitamin B12 are the important regulators of DNA methylation which play an important role in development in early life. Previous studies carried out in this regard have shown the individual effects of these vitamins but recently the focus has been to study the combined effects of both the vitamins during pregnancy. Therefore, this study was planned to elucidate the effect of the altered dietary ratio of folate and B12 on the expression of transporters, related miRNAs and DNA methylation in C57BL/6 mice. Female mice were fed diets with 9 combinations of folate and B12 for 4 weeks. They were mated and off-springs born (F1) were continued on the same diet for 6 weeks post-weaning. Maternal and fetal (F2) tissues were collected at day 20 of gestation. Deficient state of folate led to an increase in the expression of folate transporters in both F1 and F2 generations, however, B12 deficiency (BDFN) also led to an increase in the expression in both the generations. B12 transporters/proteins were found to be increased with B12 deficiency in F1 and F2 generations except for TC-II in the kidney which was found to be decreased in the F1 generation. miR-483 was found to be increased with all conditions of folate and B12 in both F1 and F2 generations, however, deficient conditions of B12 led to an increase in the expression of miR-221 in both F1 and F2 generations. The level of miR-133 was found to be increased in BDFN group in F1 generation however; in F2 generation the change in expression was tissue and sex-specific. Global DNA methylation was decreased with deficiency of both folate and B12 in maternal tissues (F1) but increased with folate deficiency in placenta (F1) and under all conditions in fetal tissues (F2). DNA methyltransferases were overall found to be increased with deficiency of folate and B12 in both F1 and F2 generations. Results suggest that the dietary ratio of folate and B12 resulted in altered expression of transporters, miRNAs, and genomic DNA methylation in association with DNMTs.

Highlights

DNA methylation, a central component of the epigenetic network is altered in response to nutritional influences
Pairwise comparison revealed that the % increase in the body weight of mice (F1) was less under the setting of folate and vitamin B12 deficiency i.e. BNFD (39.5%), BDFN (34.5%), B12 deficiency in combination with folate deficiency (BDFD) (28.2%) and B12 deficiency in combination with folate over-supplementation (BDFO) (14.7%) groups compared to control (BNFN) animals (66.1%) at the time of mating i.e. after 6 weeks of dietary treatment (Table 1)
In BDFO group, most of the animals exhibited a high rate of mortality (5 females (F1) out of 12 were left at the time of mating) and total infertility was observed, no data related to BDFO is present in the manuscript for the F2 generation

Summary

Introduction

DNA methylation, a central component of the epigenetic network is altered in response to nutritional influences. On comparing the effect of folate deficiency with either condition of B12 in comparison to control, an increase in expression of PCFT gene was observed regardless of sex in all fetal tissues (BNFN) vs BNFD, BDFD, BOFD).

Results

Conclusion