Contracting CAG/CTG repeats using the CRISPR-Cas9 nickase.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 27827362.
- Also identified by DOI 10.1038/ncomms13272 and PMC identifier 5105158.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
CAG/CTG repeat expansions cause over 13 neurological diseases that remain without a cure. Because longer tracts cause more severe phenotypes, contracting them may provide a therapeutic avenue. No currently known agent can specifically generate contractions. Using a GFP-based chromosomal reporter that monitors expansions and contractions in the same cell population, here we find that inducing double-strand breaks within the repeat tract causes instability in both directions. In contrast, the CRISPR-Cas9 D10A nickase induces mainly contractions independently of single-strand break repair. Nickase-induced contractions depend on the DNA damage response kinase ATM, whereas ATR inhibition increases both expansions and contractions in a MSH2- and XPA-dependent manner. We propose that DNA gaps lead to contractions and that the type of DNA damage present within the repeat tract dictates the levels and the direction of CAG repeat instability. Our study paves the way towards deliberate induction of CAG/CTG repeat contractions in vivo.
Medical subject headings
- CRISPR-Cas Systems
- DNA Breaks, Single-Stranded
- DNA Repair
- Deoxyribonuclease I
- Trinucleotide Repeat Expansion