Transient DNMT1 suppression reveals hidden heritable marks in the genome

Area of Science:

• Epigenetics
• Developmental Biology
• Genomics

Background:

• Dynamic DNA methylation and remethylation are critical for early embryogenesis.
• Imprinted germline differentially methylated domains (gDMDs) must maintain their methylation status across these waves.
• Understanding epigenetic inheritance beyond gDMDs is essential for developmental processes.

Purpose of the Study:

• To identify novel gDMD-like sequences with similar epigenetic inheritance properties.
• To investigate the role of DNA methyltransferase 1 (DNMT1) in maintaining methylation at these sequences.
• To explore the in vivo relevance of these regions during preimplantation development.

Main Methods:

• Utilized a modified embryonic stem (ES) cell line to mimic early embryonic demethylation/remethylation.
• Employed transient DNMT1 suppression in ES cells to identify methylation-dependent regions.
• Developed a mouse model with transient DNMT1 loss in preimplantation embryos to assess in vivo remethylation.

Main Results:

• Discovered novel gDMD-like sequences that necessitate continuous DNMT1 activity for sustained high methylation.
• Observed compromised remethylation of these sequences in vivo following transient DNMT1 loss.
• These newly identified regions exhibit heritable epigenetic features akin to imprinted gDMDs.

Conclusions:

• Identified novel epigenetic regions with heritable features similar to imprinted gDMDs.
• These regions are crucial for normal physiological and developmental processes.
• Disruption of these regions is associated with developmental disorders, including cancer and autism spectrum disorders.