Folic acid supplementation alleviates reduced ureteric branching, nephrogenesis, and global DNA methylation induced by maternal nutrient restriction in rat embryonic kidney

We previously reported that maternal nutrient restriction (NR) inhibited ureteric branching, metanephric growth, and nephrogenesis in the rat. Here we examined whether folic acid, a methyl-group donor, rescues the inhibition of kidney development induced by NR and whether DNA methylation is involved in it. The offspring of dams given food ad libitum (CON) and those subjected to 50% food restriction (NR) were examined. NR significantly reduced ureteric tip number at embryonic day 14, which was attenuated by folic acid supplementation to nutrient restricted dams. At embryonic day 18, glomerular number, kidney weight, and global DNA methylation were reduced by NR, and maternal folic acid supplementation again alleviated them. Among DNA methyltransferases (DNMTs), DNMT1 was strongly expressed at embryonic day 15 in CON but was reduced in NR. In organ culture, an inhibitor of DNA methylation 5-aza-2 '-deoxycytidine as well as medium lacking methyl donors folic acid, choline, and methionine, significantly decreased ureteric tip number and kidney size mimicking the effect of NR. In conclusion, global DNA methylation is necessary for normal kidney development. Folic acid supplementation to nutrient restricted dams alleviated the impaired kidney development and DNA methylation in the offspring.