DNA-binding motif and target genes of the imprinted transcription factor PEG3

The Peg3 gene is expressed only from the paternally inherited allele located on proximal mouse chromosome 7. The PEG3 protein encoded by this imprinted gene is predicted to bind DNA based on its multiple zinc finger motifs and nuclear localization. In the current study, we demonstrated PEG3's DNA-binding ability by characterizing its binding motif and target genes. We successfully identified target regions bound by PEG3 from mouse brain extracts using chromatin immunoprecipitation analysis. PEG3 was demonstrated to bind these candidate regions through the consensus DNA-binding motif AGTnnCnnnTGGCT. In vitro promoter assays established that PEG3 controls the expression of a given gene through this motif. Consistent with these observations, the transcriptional levels of a subset of the target genes are also affected in a mutant mouse model with reduced levels of PEG3 protein. Overall, these results confirm PEG3 as a DNA-binding protein controlling specific target genes that are involved in distinct cellular functions.