The Journal of Clinical Investigation (Feb 2023)

Mini-dCas13X–mediated RNA editing restores dystrophin expression in a humanized mouse model of Duchenne muscular dystrophy

  • Guoling Li,
  • Ming Jin,
  • Zhifang Li,
  • Qingquan Xiao,
  • Jiajia Lin,
  • Dong Yang,
  • Yuanhua Liu,
  • Xing Wang,
  • Long Xie,
  • Wenqin Ying,
  • Haoqiang Wang,
  • Erwei Zuo,
  • Linyu Shi,
  • Ning Wang,
  • Wanjin Chen,
  • Chunlong Xu,
  • Hui Yang

Journal volume & issue
Vol. 133, no. 3

Abstract

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Approximately 10% of monogenic diseases are caused by nonsense point mutations that generate premature termination codons (PTCs), resulting in a truncated protein and nonsense-mediated decay of the mutant mRNAs. Here, we demonstrate a mini-dCas13X–mediated RNA adenine base editing (mxABE) strategy to treat nonsense mutation–related monogenic diseases via A-to-G editing in a genetically humanized mouse model of Duchenne muscular dystrophy (DMD). Initially, we identified a nonsense point mutation (c.4174C>T, p.Gln1392*) in the DMD gene of a patient and validated its pathogenicity in humanized mice. In this model, mxABE packaged in a single adeno-associated virus (AAV) reached A-to-G editing rates up to 84% in vivo, at least 20-fold greater than rates reported in previous studies using other RNA editing modalities. Furthermore, mxABE restored robust expression of dystrophin protein to over 50% of WT levels by enabling PTC read-through in multiple muscle tissues. Importantly, systemic delivery of mxABE by AAV also rescued dystrophin expression to averages of 37%, 6%, and 54% of WT levels in the diaphragm, tibialis anterior, and heart muscle, respectively, as well as rescued muscle function. Our data strongly suggest that mxABE-based strategies may be a viable new treatment modality for DMD and other monogenic diseases.

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