PEG3 binds to <i>H19</i>-ICR as a transcriptional repressor

Paternally expressed gene 3 (<i>Peg3</i>) encodes a DNA-binding protein with 12 C2H2 zinc finger motifs. In the current study, we performed ChIP-seq using mouse embryonic fibroblast (MEF) cells. This experiment identified a set of 16 PEG3 genomic targets, the majority of which overlapped with the promoter regions of genes with oocyte expression. These potential downstream genes were upregulated in MEF cells lacking PEG3 protein, suggesting a potential repressor role for PEG3. Our study also identified the imprinting control region (ICR) of <i>H19</i> as a genomic target. According to the results, PEG3 binds to a specific sequence motif located between the 3^rd and 4^th CTCF binding sites of the H19-ICR. PEG3 also binds to the active maternal allele of the H19-ICR. The expression levels of <i>H19</i> were upregulated in MEF cells lacking PEG3, and this upregulation was mainly derived from the maternal allele. This suggests that PEG3 may function as a transcriptional repressor for the maternal allele of <i>H19</i>. Overall, the current study uncovers a potential functional relationship between <i>Peg3</i> and <i>H19</i>, and also confirms PEG3 as a transcriptional repressor for the identified downstream genes.