Format

Send to

Choose Destination
Cell. 2018 Feb 22;172(5):979-992.e6. doi: 10.1016/j.cell.2018.01.012. Epub 2018 Feb 15.

Rescue of Fragile X Syndrome Neurons by DNA Methylation Editing of the FMR1 Gene.

Author information

1
Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA.
2
Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Fulcrum Therapeutics, One Kendall Square, Binney Street b7102, Cambridge, MA 02139, USA.
3
Fulcrum Therapeutics, One Kendall Square, Binney Street b7102, Cambridge, MA 02139, USA.
4
Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA.
5
The Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, Jerusalem 91904, Israel.
6
Whitehead Institute for Biomedical Research, Cambridge, MA 02142, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02142, USA. Electronic address: jaenisch@wi.mit.edu.

Abstract

Fragile X syndrome (FXS), the most common genetic form of intellectual disability in males, is caused by silencing of the FMR1 gene associated with hypermethylation of the CGG expansion mutation in the 5' UTR of FMR1 in FXS patients. Here, we applied recently developed DNA methylation editing tools to reverse this hypermethylation event. Targeted demethylation of the CGG expansion by dCas9-Tet1/single guide RNA (sgRNA) switched the heterochromatin status of the upstream FMR1 promoter to an active chromatin state, restoring a persistent expression of FMR1 in FXS iPSCs. Neurons derived from methylation-edited FXS iPSCs rescued the electrophysiological abnormalities and restored a wild-type phenotype upon the mutant neurons. FMR1 expression in edited neurons was maintained in vivo after engrafting into the mouse brain. Finally, demethylation of the CGG repeats in post-mitotic FXS neurons also reactivated FMR1. Our data establish that demethylation of the CGG expansion is sufficient for FMR1 reactivation, suggesting potential therapeutic strategies for FXS.

KEYWORDS:

CGG repeats; CRISPR/Cas9; DNA methylation editing; FMR1 reactivation; fragile X syndrome

Comment in

PMID:
29456084
DOI:
10.1016/j.cell.2018.01.012
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Elsevier Science
Loading ...
Support Center