Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2021 Jul 29;12:696280. doi: 10.3389/fimmu.2021.696280

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2021 Qin, Scicluna and van der Poll

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

PMC Copyright notice

DNA methylation cycle. DNMTs catalyze the addition of a methyl group to the fifth carbon position of cytosine to generate methylated cytosine (5mC), which is maintained by DNMT1 (green arrow); 5mC is oxidized to 5-hydroxymethylcytosine (5hmC), which can be further oxidized to 5-formylcytosine (5fC) and 5-carboxylcytosine (5caC) by TETs. The higher oxidized cytosine bases 5fC and 5caC can then be converted back to their unmodified state directly by thymine DNA glycosylase (TDG) and subsequently base excision repair (BER) processing; these oxidative steps contribute to active demethylation (red arrow). Passive demethylation removes 5mC from all forms of methylcytosine due to absence or reduction in DNMT levels and function (blue arrow).