Nonruminant Nutrition Symposium I
Environmental factors including maternal diet during periconception and pregnancy can immediately impact fetal growth and development and have long-term consequences on phenotypic outcomes of the offspring, a phenomenon known as “fetal programming” by which the in utero environmental cues regulate specific gene functions via epigenetic modifications. This prompted us to investigate the effects of a methylating micronutrient-rich maternal diet in pregnant Pietrain sows fed either a standard (CON) or supplemented diet with methionine, folate, choline, B6, B12, and zinc (MET). Our results showed an association between increased fetal weight and MET. Microarray-based transcriptional responses of the liver were analyzed at 35, 63, and 91-days post-conception (dpc). Altered insulin-like growth factor (IGF) signaling led us to investigate IGF-2 and insulin-like growth factor binding proteins (IGFBPs) in the muscle and liver. Indeed, weight differences and modulated IGF pathways reflected increased and decreased levels of the muscle IGF-2 and IGFBP-2 in MET, respectively. We extended the study to further investigate the effects of MET on transcriptome and DNA-methylation of the liver at two ontogenetic stages (91-dpc (fetal) and 150-days post-natal (adult)) and breeds (German-Landrace and Pietrain) using RNA-Seq and bisulfite-sequencing (RRBS). The results showed numerous differentially expressed genes (DEGs) depending on stage, sex, breed and maternal diet. Ingenuity Pathway Analysis of DEGs (MET vs CON) highlighted regulations of genes related to nucleic acid metabolisms including DOT1L, SLBP, TCF3 and RPA1 in the fetuses, while genes involved in lipid metabolisms including PON3, ACSM2B, CYP4F2 and LDHB were altered by MET in the adults. Several genes showed an inverse relationship between gene expression and DNA-methylation state of the promoter including CBFA2T3, CPEB4 and TUBB4B. Altogether, our results provide evidence demonstrating immediate and long-term consequences of methylating micronutrient supplementation during pregnancy on phenotypic outcomes of the pig offspring reinforcing epigenetic modulation via intervening maternal diet.