PEG3 binds to H19-ICR as a transcriptional repressor

Abstract

Paternally expressed gene 3 (Peg3) 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 H19 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 H19 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 H19. Overall, the current study uncovers a potential functional relationship between Peg3 and H19, and also confirms PEG3 as a transcriptional repressor for the identified downstream genes.

Allele and dosage specificity of the Peg3 imprinted domain

“…We also performed a similar series of expression analyses for the following genes: Oxtr , Avp , Oxt , Peg10 and Msl1 ( Fig 5 ). The three genes ( Oxtr , Oxt and Avp ) and Peg3 have been shown to be involved in maternal-caring behaviors and controlling the volume of bodily fluids [ 23 , 24 ], while Msl1 and Peg10 are known to be downstream targets of Peg3 [ 25 – 27 ]. For this series of expression analyses, we used male (n = 3) and female (n = 3) cDNA sets that had been generated using the total RNA from neonatal heads and adult hypothalamus.…”

PEG3 control on the mammalian MSL complex

“…For this and the current study, MEFs have been selected as an in vitro system of choice since Peg3 is highly expressed in this homogenous cell population [14]. The paternal transmission of the CoKO (Conditional KnockOut-ready) allele is designed to deplete the majority of the PEG3 protein owing to the transcriptional truncation of Peg3 at the 5 th intron [7].…”

“…In terms of protein function, the ORF (Open Reading Frame) of PEG3 contains several protein motifs that are frequently associated with DNA-binding proteins, such as SCAN and KRAB-A boxes at the N-terminal portion and C2H2-Kruppel-type zinc finger motifs at the C-terminal portion [9–11]. Consistent with this, genome-wide ChIP-seq analyses have indeed identified many genomic targets as its downstream genes [12–14]. Several series of in vitro analyses further revealed that PEG3 is a transcriptional repressor for the downstream genes [12–15], and also that the PEG3-driven repression may be mediated through the interaction with a co-repressor protein KAP1 (Kruppel-associated protein 1) [11].…”

Oxytocin receptor is regulated by Peg3

“…PEG3 also contains a KRAB-A domain, thus is predicted to be a transcriptional repressor through its interaction with KAP1 [ 8 ]. This predicted repression function has been further confirmed through the observation that the expression levels of its downstream genes are usually up-regulated in the tissues of the mouse mutant models targeting Peg3 [ 6 , 7 ]. According to the results from mouse knockout (KO) models, Peg3 is also involved in controlling fetal growth rates and maternal-caring behaviors [ 9 – 13 ].…”