Cell
Volume 167, Issue 1, 22 September 2016, Pages 233-247.e17
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Editing DNA Methylation in the Mammalian Genome

https://doi.org/10.1016/j.cell.2016.08.056Get rights and content
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Highlights

  • dCas9-Tet1 and -Dnmt3a enable precise editing of CpG methylation in vitro and in vivo

  • Targeted demethylation of BDNF promoter IV activates BDNF in neurons

  • Targeted enhancer demethylation facilitates MyoD-induced muscle cell reprogramming

  • Targeted de novo methylation of CTCF motifs alters CTCF-mediated gene loops

Summary

Mammalian DNA methylation is a critical epigenetic mechanism orchestrating gene expression networks in many biological processes. However, investigation of the functions of specific methylation events remains challenging. Here, we demonstrate that fusion of Tet1 or Dnmt3a with a catalytically inactive Cas9 (dCas9) enables targeted DNA methylation editing. Targeting of the dCas9-Tet1 or -Dnmt3a fusion protein to methylated or unmethylated promoter sequences caused activation or silencing, respectively, of an endogenous reporter. Targeted demethylation of the BDNF promoter IV or the MyoD distal enhancer by dCas9-Tet1 induced BDNF expression in post-mitotic neurons or activated MyoD facilitating reprogramming of fibroblasts into myoblasts, respectively. Targeted de novo methylation of a CTCF loop anchor site by dCas9-Dnmt3a blocked CTCF binding and interfered with DNA looping, causing altered gene expression in the neighboring loop. Finally, we show that these tools can edit DNA methylation in mice, demonstrating their wide utility for functional studies of epigenetic regulation.

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Co-first author

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Present address: School of Life Sciences, Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China

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Lead Contact