Preventing transcriptional gene silencing by active DNA demethylation

Avnish Kapoor, Fernanda Agius, Jian Kang Zhu

Research output: Contribution to journalShort surveypeer-review

66 Scopus citations


DNA methylation is important for stable transcriptional gene silencing. DNA methyltransferases for de novo as well as maintenance methylation have been well characterized. However, enzymes responsible for active DNA demethylation have been elusive and several reported mechanisms of active demethylation have been controversial. There has been a critical need for genetic analysis in order to firmly establish an in vivo role for putative DNA demethylases. Mutations in the bifunctional DNA glycosylase/lyase ROS1 in Arabidopsis cause DNA hypermethylation and transcriptional silencing of specific genes. Recombinant ROS1 protein has DNA glycosylase/lyase activity on methylated but not unmethylated DNA substrates. Therefore, there is now strong genetic evidence supporting a base excision repair mechanism for active DNA demethylation. DNA demethylases may be critical factors for genome wide hypomethylation seen in cancers and possibly important for epigenetic reprogramming during somatic cell cloning and stem cell function.

Original languageEnglish (US)
Pages (from-to)5889-5898
Number of pages10
JournalFEBS Letters
Issue number26
StatePublished - Oct 31 2005


  • Arabidopsis
  • DNA demethylation
  • DNA glycosylase
  • DNA methylation
  • ROS1
  • Transcriptional gene silencing

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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