GSE50034
Restricted Feeding Reveals Maternal Entrainment of Weak Circadian Oscillators in Fetal Mouse Livers
Although circadian clocks oscillate in most cells, it has been difficult to detect canonical expression of clock genes in fetal rodent tissues, including the fetal liver. The oscillation status of fetal clocks and the maternal influence on these clocks have not yet been conclusively defined. Here we report that, when the mother mice are under restricted feeding, the expression rhythms of several clock genes can be detected in fetal mouse livers. Those rhythms, although of low amplitude, reversed their profiles under opposite feeding cycles, suggesting maternal entrainment of the weak fetal liver clocks. However, Bmal1 could show biphasic expression in the fetal livers. The expression of some metabolic genes (e.g. Insig1) also showed biphasic daily changes in fetal livers, possibly as a result of interactions between the unique in utero milieu and the fetal liver clocks. Regular rhythms of clock gene expression were detected in dissociated fetal hepatocytes in culture. Differential expression of metabolic genes were found between fetal and adult livers, suggesting that metabolic features affected clock amplitude. Genome-wide differences in DNA methylation were also found between adult and fetal livers. Some of those epigenetic changes were likely critical for the developmental changes in clock amplitudes. Overall design: The whole genome methylation status of two samples (Fetal and Adult) were analysed by reduced representational bisulfite sequencing (RRBS)