Maternal high fat diet during pregnancy and lactation alters hepatic expression of insulin like growth factor-2 and key microRNAs in the adult offspring

Background: miRNAs play important roles in the regulation of gene functions. Maternal dietary modifications during pregnancy and gestation have long-term effects on the offspring, but it is not known whether a maternal high fat (HF) diet during pregnancy and lactation alters expression of key miRNAs in the offspring. Results: We studied the effects of maternal HF diet on the adult offspring by feeding mice with either a HF or a chow diet prior to conception, during pregnancy and lactation, and all offspring were weaned onto the same chow diet until adulthood. Maternal HF fed offspring had markedly increased hepatic mRNA levels of peroxisome proliferator activated receptor-alpha (ppar-alpha) and carnitine palmitoyl transferase-1a (cpt-1a) as well as insulin like growth factor-2 (Igf2). A HF diet induced up-regulation of ppar-alpha and cpt-1a expression in the wild type but not in Igf2 knock out mice. Furthermore, hepatic expression of let-7c was also reduced in maternal HF fed offspring. Among 579 miRNAs measured with microarray, similar to 23 miRNA levels were reduced by similar to 1.5-4.9-fold. Reduced expression of miR-709 ( a highly expressed miRNA), miR-122, miR-192, miR-194, miR-26a, let-7a, let7b and let-7c, miR-494 and miR-483* ( reduced by similar to 4.9 fold) was validated by qPCR. We found that methyl-CpG binding protein 2 was the common predicted target for miR- 709, miR-let7s, miR-122, miR-194 and miR-26a using our own purpose-built computer program. Conclusion: Maternal HF feeding during pregnancy and lactation induced co-ordinated and long-lasting changes in expression of Igf2, fat metabolic genes and several important miRNAs in the offspring.