🎙️ Episode 27: Nucleocytosolic Vehicles — A CRISPR RNP Delivery Breakthrough

🧬 In this episode of Base by Base, we delve into a novel virus-like particle (VLP) platform, ENVLPE, developed by Geilenkeuser et al. (2025) in Cell. This innovation harnesses nucleocytosolic shuttling and RNA aptamer recruitment to efficiently package and deliver fully assembled CRISPR ribonucleoproteins (RNPs), overcoming spatial and loading limitations of previous VLP approaches.

🔍 Main Highlights:
The ENVLPE system integrates a PP7 coat protein into the HIV-1 Gag polyprotein and appends PP7-tagged guide RNAs to selectively load base editors, prime editors, nucleases, and trans-activators as RNPs rather than mRNA or protein fusions.
Active nuclear export and localization signals shuttle editor RNPs into the cytosol, synchronizing RNP assembly with VLP budding and greatly enhancing packaging efficiency.
Co-expression of the RNA endonuclease Csy4, which remains bound to a 3′ hairpin on pegRNAs, protects guide RNAs from degradation and substantially boosts prime editing performance under low-dose conditions.
A streamlined “miniENVLPE” variant retaining only essential Gag elements and coiled-coil oligomerization domains matches full-length editing efficiency, demonstrating the platform’s modularity and scalability.
In vivo subretinal delivery of ENVLPE in mouse models achieves robust editor uptake by retinal cells and functional gene correction in inherited eye disease—with minimal off-target activity.

🧠 Conclusion:
ENVLPE represents a versatile, high-efficiency vehicle for RNP delivery of CRISPR effectors in both ex vivo and in vivo settings. By combining RNA-mediated recruitment, active transport, and modular VLP engineering, this platform opens new avenues for precise therapeutic genome editing.

📖 Reference:
Geilenkeuser, J., Armbrust, N., Steinmaßl, E., et al. (2025). Engineered nucleocytosolic vehicles for loading of programmable editors. Cell, 188, 2637–2655. https://doi.org/10.1016/j.cell.2025.03.015

📜 License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International (CC BY 4.0) license – https://creativecommons.org/licenses/by/4.0/