What is the Difference Between De Novo Methylation and Maintenance Methylation?

De novo methylation and maintenance methylation are two crucial processes involved in DNA methylation, an essential epigenetic mechanism for transcriptional regulation, silencing of transposable elements, and genome stabilization. The main differences between de novo methylation and maintenance methylation are:

1. Enzymes involved: De novo methylation utilizes the enzymes DNMT3A and DNMT3B, while maintenance methylation involves only one enzyme, DNMT1.
2. Function: De novo methylation is responsible for adding methyl groups to unmethylated DNA at specific CpG sites, establishing new methylation patterns during embryonic development. Maintenance methylation, on the other hand, is responsible for copying DNA methylation patterns to the daughter strands during DNA replication, ensuring the preservation of the original pattern of DNA methylation.
3. Timing: De novo methylation occurs during embryonic development, while maintenance methylation takes place during DNA replication in both embryonic and adult cells.
4. Methylation patterns: De novo methylation is involved in compartmentalizing the genome during tissue differentiation, resulting in the establishment of tissue-specific gene expression patterns. Maintenance methylation ensures the faithful transmission of these patterns between cell generations.

In summary, de novo methylation is responsible for establishing new methylation patterns, while maintenance methylation ensures the preservation and faithful transmission of these patterns between cell generations.

Comparative Table: De Novo Methylation vs Maintenance Methylation

Here is a table summarizing the differences between de novo methylation and maintenance methylation:

De novo methylation is the process by which methyl groups are added to unmethylated DNA, while maintenance methylation ensures the faithful replication of existing methylation patterns during DNA replication. Both processes play essential roles in epigenetic regulation and are catalyzed by different enzymes, with de novo methylation being carried out by DNMT3A and DNMT3B and maintenance methylation being carried out by DNMT1.