Genomic imprinting defect in Zfp57 mutant iPS cell lines

Area of Science:

• Genetics and Epigenetics
• Stem Cell Biology
• Genomic Imprinting

Background:

• Genomic imprinting is an epigenetic phenomenon that leads to parent-specific gene expression.
• Zinc finger protein 57 (ZFP57) is known to maintain DNA methylation imprints in mouse embryos and embryonic stem cells.
• The role of ZFP57 in the reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) remains largely unexplored.

Purpose of the Study:

• To investigate the role of ZFP57 in maintaining genomic imprinting during the process of iPSC reprogramming.
• To determine if ZFP57 is essential for the inheritance of DNA methylation marks at imprinted loci during iPSC generation.

Main Methods:

• Induced pluripotent stem cells (iPSCs) were generated from mouse embryonic fibroblasts (MEFs) using retroviral expression of reprogramming factors.
• The presence or absence of ZFP57 (maternal or zygotic) was analyzed in derived iPSC clones.
• DNA methylation patterns at four specific imprinted regions (Peg1, Peg3, Snrpn, and Dlk1-Dio3) were assessed in ZFP57-expressing and ZFP57-deficient iPSCs.

Main Results:

• Parentally derived DNA methylation imprints were largely maintained in iPSC clones that expressed ZFP57.
• In contrast, DNA methylation imprints were significantly lost in iPSC clones lacking maternal or zygotic ZFP57.
• Interestingly, loss of zygotic ZFP57 led to imprint erasure at Peg1 and Peg3, while imprints at Snrpn and Dlk1-Dio3 were retained.

Conclusions:

• ZFP57 plays a critical role in preserving genomic imprinting during iPSC reprogramming.
• The absence of ZFP57 leads to the loss of essential DNA methylation marks at specific imprinted loci.
• Differential retention of imprints in ZFP57-deficient iPSCs suggests complex regulatory mechanisms that warrant further investigation.