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Science. 2011 Sep 2;333(6047):1303-7. doi: 10.1126/science.1210944. Epub 2011 Aug 4.

Tet-mediated formation of 5-carboxylcytosine and its excision by TDG in mammalian DNA.

Author information

1
Group of DNA Metabolism, State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.

Abstract

The prevalent DNA modification in higher organisms is the methylation of cytosine to 5-methylcytosine (5mC), which is partially converted to 5-hydroxymethylcytosine (5hmC) by the Tet (ten eleven translocation) family of dioxygenases. Despite their importance in epigenetic regulation, it is unclear how these cytosine modifications are reversed. Here, we demonstrate that 5mC and 5hmC in DNA are oxidized to 5-carboxylcytosine (5caC) by Tet dioxygenases in vitro and in cultured cells. 5caC is specifically recognized and excised by thymine-DNA glycosylase (TDG). Depletion of TDG in mouse embyronic stem cells leads to accumulation of 5caC to a readily detectable level. These data suggest that oxidation of 5mC by Tet proteins followed by TDG-mediated base excision of 5caC constitutes a pathway for active DNA demethylation.

PMID:
21817016
PMCID:
PMC3462231
DOI:
10.1126/science.1210944
[Indexed for MEDLINE]
Free PMC Article

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