Figure 3. . Dynamics of 5-methylcytosine, 5-hydroxymethylcytosine, DNA methyltransferases and ten-eleven translocations during neurogenesis.

DNMT1 and DNMT3a are relatively stably expressed during neurogenesis process, while DNMT3b is highly expressed in ESCs and primarily expressed in NPCs in mammal central neural system. TET1 and TET2 are robustly expressed in ESCs, while TET3 is only marginally expressed. The expression level of TET1 decreased during neurogenesis process. The expression of TET2 maintains comparable level or decreased to some extent during ESCs differentiation into NPCs, which is showed by independent studies. TET3 and TET3 are robustly expressed during NPCs differentiation into neurons. Global level of 5mC remains unchanged, while methylation dynamic in some particular regions, such as low-methylated regions, is important for neurogenesis. 5hmC level decreases dramatically (˜80%) during ESCs differentiation into NPCs, while increases doubly in neurons in comparison to NPCs.

5hmc: 5-hydroxymethylcytosine; 5mc: 5-methylcytosine; DNMT: DNA methyltransferase; ESC: Embryonic stem cell; NPC: Neural progenitor cell.