Nature Communications (May 2025)

An engineered U7 small nuclear RNA scaffold greatly increases ADAR-mediated programmable RNA base editing

  • Susan M. Byrne,
  • Stephen M. Burleigh,
  • Robert Fragoza,
  • Yue Jiang,
  • Yiannis Savva,
  • Ricky Pabon,
  • Evan Kania,
  • Joseph Rainaldi,
  • Andrew Portell,
  • Prashant Mali,
  • Adrian W. Briggs

DOI
https://doi.org/10.1038/s41467-025-60155-z
Journal volume & issue
Vol. 16, no. 1
pp. 1 – 14

Abstract

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Abstract Custom RNA base editing exploiting the human Adenosine Deaminase Acting on RNA (ADAR) enzyme may enable therapeutic gene editing without DNA damage or use of foreign proteins. ADAR’s adenosine-to-inosine (effectively A-to-G) deamination activity can be targeted to transcripts using an antisense guide RNA (gRNA), but efficacy is challenged by limits of in vivo delivery. Embedding gRNAs into a U7 small nuclear RNA (snRNA) framework greatly enhances RNA editing with endogenous ADAR, and a 750-plex single-cell mutagenesis screen further improved the framework. An optimized scaffold with a stronger synthetic U7 promoter enables 76% RNA editing in vitro from a single DNA construct per cell, and 75% editing in a Hurler syndrome mouse brain after one systemic AAV injection, surpassing circular gRNA approaches. The technology also improves published DMD exon-skipping designs 25-fold in differentiated myoblasts. Our engineered U7 framework represents a universal scaffold for ADAR-based RNA editing and other antisense RNA therapies.