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Methylation during development

During normal development and cell differentiation in mammals, a complex of changes in DNA methylation occurs.

(Fig. 2). In the zygote (immediately after fertilization), maternal and paternal chromosomes are spatially separated, and their demethylation occurs

Development time

Figure 2.

Schematic representation of temporal changes in the level of DNA methylation in mammalian cells during development

(Turker 1999). AUC is primordial germ cells, ESCs are embryonic stem cells.

at different times (Mayer et al. 2000). In this case, the paternal chromosomes are demethylated within six to eight hours after fertilization, independent of replication, while demethylation of the maternal chromosomes encompasses the stages of second and third cleavage and occurs during the replication process. In mice, as a result of this process, the genome methylation level drops to 30% of that observed in somatic cells (Kafri et al.
1992). After implantation in the blastocyst cells, the methylation level is restored, acquiring a pattern characteristic of the cells of the adult organism (Turker 1999). This process begins with de novo methylation, affecting specific sequences in the genome ("methylation centers" - transposons and repeats). After that, at the second stage of establishing the methylation pattern, methylation from the center is distributed to the surrounding unmethylated sites. During differentiation in

cells significantly decrease the ability to methylate DNA de novo (Turker et al. 1991; Szyf et al. 1990), but retain the ability to spread methylation from "methylation centers" (Toth et al. 1989). However, an exceptionally high ability to maintain the established methylation status during replication becomes a characteristic feature of cells. This process is called supporting methylation.
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Methylation during development

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  2. Petrenko A.A. DNA methylation analysis for cervical cancer, 2003
    Introduction DNA methylation Distribution of DNA methylation DNA methylation function Methylation during development Methylation enzymes Methylation as a dynamic process The role of methylation in carcinogenesis Genetic role of DNA methylation in carcinogenesis Epigenetic role of DNA methylation in carcinogenesis Comparative analysis of modern status determination methods
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