Site-directed RNA repair of endogenous Mecp2 RNA in neurons

Proc Natl Acad Sci U S A. 2017 Oct 31;114(44):E9395-E9402. doi: 10.1073/pnas.1715320114. Epub 2017 Oct 16.


Rett syndrome (RTT) is a debilitating neurological disorder caused by mutations in the gene encoding the transcription factor Methyl CpG Binding Protein 2 (MECP2). A distinct disorder results from MECP2 gene duplication, suggesting that therapeutic approaches must restore close to normal levels of MECP2. Here, we apply the approach of site-directed RNA editing to repair, at the mRNA level, a disease-causing guanosine to adenosine (G > A) mutation in the mouse MeCP2 DNA binding domain. To mediate repair, we exploit the catalytic domain of Adenosine Deaminase Acting on RNA (ADAR2) that deaminates A to inosine (I) residues that are subsequently translated as G. We fuse the ADAR2 domain, tagged with a nuclear localization signal, to an RNA binding peptide from bacteriophage lambda. In cultured neurons from mice that harbor an RTT patient G > A mutation and express engineered ADAR2, along with an appropriate RNA guide to target the enzyme, 72% of Mecp2 mRNA is repaired. Levels of MeCP2 protein are also increased significantly. Importantly, as in wild-type neurons, the repaired MeCP2 protein is enriched in heterochromatic foci, reflecting restoration of normal MeCP2 binding to methylated DNA. This successful use of site-directed RNA editing to repair an endogenous mRNA and restore protein function opens the door to future in vivo applications to treat RTT and other diseases.

Keywords: ADAR2; MeCP2; RNA editing; Rett syndrome.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Deaminase / genetics
  • Animals
  • Cells, Cultured
  • DNA Methylation / genetics
  • Disease Models, Animal
  • Humans
  • Methyl-CpG-Binding Protein 2 / genetics*
  • Mice
  • Mutation / genetics
  • Neurons / physiology*
  • RNA / genetics*
  • RNA, Messenger / genetics
  • RNA-Binding Proteins / genetics
  • Rett Syndrome / genetics


  • Methyl-CpG-Binding Protein 2
  • RNA, Messenger
  • RNA-Binding Proteins
  • RNA
  • Adenosine Deaminase