Spatially concentrated adenine base editors efficiently correct PLP1 mutations in oligodendrocytes

Area of Science:

• Biochemistry
• Molecular Biology
• Neuroscience

Background:

• Oligodendrocytes (OLs) are crucial for central nervous system myelination but are susceptible to mutations like PLP1A243V, causing Pelizaeus-Merzbacher disease (PMD).
• Current adenine base editors (ABEs) show limited efficiency in OLs for correcting these pathogenic mutations, hindering therapeutic development for PMD.

Purpose of the Study:

• To develop an enhanced adenine base editor (cABE) strategy for efficient gene correction in oligodendrocytes.
• To improve the delivery and efficacy of base editing tools for treating genetic myelin disorders like PMD.

Main Methods:

• Developed a spatially concentrated ABE (cABE) by recruiting tRNA adenosine deaminase (TadA*) to genomic targets using a SunTag system.
• Created an AAV-compatible variant (cABE-2.0) using eNme2-C Cas9 for in vivo applications, which forms dynamic nuclear puncta.
• Assessed editing efficiency, off-target effects, and functional rescue in OLs with the PLP1A243V mutation.

Main Results:

• The cABE strategy significantly enhanced on-target editing efficiency in OLs by promoting nuclear translocation and local enrichment of TadA*.
• cABE-2.0 demonstrated robust editing in vivo, forming liquid-like nuclear puncta that improved efficiency and reduced off-target effects.
• Correction of the PLP1A243V mutation in OLs restored protein localization and rescued myelination phenotypes.

Conclusions:

• Spatial reorganization of base editors is a powerful principle for enhancing editing in challenging cell types like OLs.
• The developed cABE system offers a promising gene therapy framework for Pelizaeus-Merzbacher disease and other myelin disorders.
• This approach provides a mechanistic and technical advancement for base editing applications in neurological diseases.