In our primate model of maternal high fat diet exposure, we have described that fetal epigenomic modifications to the peripheral circadian Npas2 are associated with persistent alterations in fetal hepatic metabolism and non-alcoholic fatty liver. As the interaction of circadian response with metabolism is not well understood, we employed a murine knockout model to characterize the molecular mechanisms with which Npas2 reprograms the fetal hepatic metabolic response. cDNA was generated from Npas2-/- and +/+ (wild type) livers at day 2 (newborn) and at 25 weeks (adult) of life. Newborn samples were analyzed by exon array (n = 3/cohort). Independent pathway analysis software determined that the primary dysregulated pathway(s) in the Npas2-/- animals uniformly converged on lipid metabolism. Of particular interest, Ppargc1a, which integrates circadian and metabolism pathways, was significantly (p < .01) over expressed in newborn (1.7 fold) and adult (1.8 fold) Npas2-/- animals. These findings are consistent with an essential role for Npas2 in programming the peripheral circadian response and hepatic metabolism, which has not been previously described.
Keywords: Circadian gene regulation; Circadian metabolism; Fetal circadian responses; Hepatic metabolism.