Coiled-coil heterodimer-mediated split base editing systems enable flexible and robust nucleotide substitutions.

Area of Science:

• Molecular Biology
• Gene Editing Technologies

Background:

• Base editors (BEs) offer precise base substitutions but are too large for adeno-associated virus (AAV) delivery.
• This size limitation hinders their application in in vivo gene editing therapies.

Purpose of the Study:

• To engineer a split base editor system compatible with AAV packaging.
• To assess the editing efficiency and in vivo applicability of the novel split base editor system.

Main Methods:

• Designed a split base editor system by fusing deaminases to Cas9 nickase via coiled-coil heterodimers.
• Developed cytidine base editors (CC-CBE) and adenine base editors (CC-ABE) and their derivatives.
• Evaluated editing efficiency in various cell types and in vivo mouse models.

Main Results:

• The split base editors (CC-BEs) maintained or enhanced editing efficiency compared to unsplit BEs.
• CC-CBE achieved up to 12.4-fold enhancement in primary somatic cells.
• CC-ABE demonstrated successful in vivo A-to-G conversion in Pcsk9 and Dmd genes using dual-AAV vectors in mice.

Conclusions:

• Developed a simple, universal split base editor strategy to overcome AAV packaging constraints.
• The CC-BE system enables efficient in vivo base editing without compromising precision.
• This approach broadens the potential of base editing for therapeutic applications.