The DNMT1 intrinsically disordered domain regulates genomic methylation during development.

Area of Science:

• Epigenetics and Gene Regulation
• Molecular Biology
• Developmental Biology

Background:

• The DNA methyltransferase 1 (DNMT1) enzyme is crucial for maintaining DNA methylation patterns.
• DNMT1 possesses a large intrinsically disordered domain (IDD) previously implicated in regulating DNA methylation.
• Understanding the role of DNMT1's IDD in vivo is essential for comprehending epigenetic inheritance.

Purpose of the Study:

• To investigate the in vivo function of the DNMT1 intrinsically disordered domain (IDD).
• To determine how mutations within the DNMT1 IDD affect DNA methylation patterns during embryonic development.
• To distinguish between different DNMT1-dependent methylation processes.

Main Methods:

• Generation of seven distinct mouse lines with targeted mutations in the DNMT1 IDD.
• Analysis of DNA methylation levels in homozygous mutant mice, focusing on imprinted and nonimprinted (global) sequences.
• Assessment of embryonic and fetal development in mutant mouse lines.

Main Results:

• Five out of seven mutant mouse lines developed normally with unaltered DNA methylation.
• Two mutant lines exhibited altered imprinted and/or global DNA methylation during embryonic development.
• One specific DNMT1 variant maintained imprinted methylation but showed drastically reduced global methylation, impacting fetal development.

Conclusions:

• At least two distinct DNMT1-dependent methylation processes are critical for fetal development.
• One process maintains global genomic methylation, while another preserves methylation on specific sequences like gametic differentially methylated domains (gDMDs).
• The DNMT1 IDD plays a vital role in orchestrating these distinct methylation maintenance pathways.