DNA methylation changes during preimplantation development reveal inter-species differences and reprogramming events...

Area of Science:

• Epigenetics
• Developmental Biology
• Genomics

Background:

• Preimplantation embryos undergo epigenetic reprogramming, resetting DNA methylation inherited from gametes.
• Previous studies highlighted species differences in DNA methylation patterns between human and mouse embryos.
• Understanding these patterns is crucial for reproductive biology and developmental processes.

Purpose of the Study:

• To investigate genome-wide DNA methylation and transcriptome dynamics in pig and cow preimplantation embryos.
• To compare epigenetic reprogramming in livestock species with human and mouse models.
• To identify imprinted loci and understand their regulation during early development.

Main Methods:

• Generation of genome-wide DNA methylation and whole-transcriptome datasets from gametes to blastocysts in pigs and cows.
• Analysis of DNA methylation landscapes, including bimodal patterns and hypomethylation.
• Identification of germline differentially methylated regions (gDMRs) and imprinted genes.

Main Results:

• Pig and cow oocytes exhibit a bimodal methylation landscape, with hypermethylated domains prevalent, similar to humans.
• A species-specific methylation pattern persists to the blastocyst stage, with pig blastocysts being highly hypomethylated.
• Evidence of transient de novo methylation and imprint stabilization was observed in pig embryos, with absence of ZFP57 but presence of ZNF445.

Conclusions:

• Significant species differences exist in DNA methylation reprogramming during preimplantation development.
• Porcine and bovine models may offer closer parallels to human epigenetic reprogramming than the mouse model.
• These findings advance our understanding of epigenetic regulation in early mammalian development.