DNA Demethylation in Zebrafish Involves the Coupling of a Deaminase, a Glycosylase, and Gadd45

Kunal Rai, Ian J. Huggins, Smitha R. James, Adam R Karpf, David A. Jones, Bradley R. Cairns

Research output: Contribution to journalArticle

501 Citations (Scopus)

Abstract

Evidence for active DNA demethylation in vertebrates is accumulating, but the mechanisms and enzymes remain unclear. Using zebrafish embryos we provide evidence for 5-methylcytosine (5-meC) removal in vivo via the coupling of a 5-meC deaminase (AID, which converts 5-meC to thymine) and a G:T mismatch-specific thymine glycosylase (Mbd4). The injection of methylated DNA into embryos induced a potent DNA demethylation activity, which was attenuated by depletion of AID or the non enzymatic factor Gadd45. Remarkably, overexpression of the deaminase/glycosylase pair AID/Mbd4 in vivo caused demethylation of the bulk genome and injected methylated DNA fragments, likely involving a G:T intermediate. Furthermore, AID or Mbd4 knockdown caused the remethylation of a set of common genes. Finally, Gadd45 promoted demethylation and enhanced functional interactions between deaminase/glycosylase pairs. Our results provide evidence for a coupled mechanism of 5-meC demethylation, whereby AID deaminates 5-meC, followed by thymine base excision by Mbd4, promoted by Gadd45.

Original languageEnglish (US)
Pages (from-to)1201-1212
Number of pages12
JournalCell
Volume135
Issue number7
DOIs
StatePublished - Dec 26 2008
Externally publishedYes

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5-Methylcytosine
Zebrafish
Thymine
DNA
Embryonic Structures
Genes
Vertebrates
Genome
Injections
Enzymes

Keywords

  • CELLBIO
  • DEVBIO
  • DNA

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

Cite this

DNA Demethylation in Zebrafish Involves the Coupling of a Deaminase, a Glycosylase, and Gadd45. / Rai, Kunal; Huggins, Ian J.; James, Smitha R.; Karpf, Adam R; Jones, David A.; Cairns, Bradley R.

In: Cell, Vol. 135, No. 7, 26.12.2008, p. 1201-1212.

Research output: Contribution to journalArticle

Rai, Kunal ; Huggins, Ian J. ; James, Smitha R. ; Karpf, Adam R ; Jones, David A. ; Cairns, Bradley R. / DNA Demethylation in Zebrafish Involves the Coupling of a Deaminase, a Glycosylase, and Gadd45. In: Cell. 2008 ; Vol. 135, No. 7. pp. 1201-1212.
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