ac4C Boosts Synthetic mRNA Output 3.5-Fold, Outperforming m1Ψ on Fidelity
Updated
Updated · Nature.com · Jul 1
ac4C Boosts Synthetic mRNA Output 3.5-Fold, Outperforming m1Ψ on Fidelity
2 articles · Updated · Nature.com · Jul 1
Summary
ac4C-modified synthetic mRNA produced higher protein output than the standard m1Ψ across cell lines, primary human dendritic cells and mouse liver, while suppressing inflammatory responses to similar levels.
Single-molecule imaging showed the key difference was translation speed: m1Ψ slowed elongation nearly twofold versus ac4C, increasing ribosome collisions, quality-control engagement and reducing productive protein synthesis.
In mice, 10 μg of ac4C NanoLuc mRNA in lipid nanoparticles generated about 3.5-fold higher liver luminescence than m1Ψ at 24 hours, despite residual hepatic m1Ψ mRNA levels being higher.
Frameshift tests found +1 frameshifting from m1Ψ-modified reporters reached about 10% of wild-type output in cells, while ac4C stayed near background, indicating better translational fidelity.
The study positions elongation rate as a design lever for mRNA therapeutics, suggesting ac4C may suit applications needing accurate, high-yield protein production even as m1Ψ remains the clinical standard.
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ac4C Outperforms m1Ψ: A New Standard for Safe and Faithful mRNA Therapeutics
Overview
Recent advances in mRNA therapeutics highlight a major shift from the widely used N1-methylpseudouridine (m1Ψ), which can compromise translational fidelity and generate unintended neoantigens, to the promising alternative N4-acetylcytidine (ac4C). This breakthrough is driven by a deeper understanding of how nucleotide modifications, like ac4C, introduce mild slowdowns during protein synthesis, preventing harmful ribosomal traffic jams and supporting faithful translation. As a result, ac4C addresses key safety and efficacy concerns, paving the way for safer, more reliable mRNA medicines and marking a new era in therapeutic development.