The research group led by Chen Peng from the College of Chemistry and Molecular Engineering at Peking University, in collaboration with Yi Chengqi's group from the School of Life Sciences, has developed a novel RNA codon expansion (RCE) technology that enables precise insertion of non-canonical amino acids (ncAAs) in mammalian cells without interfering with endogenous gene expression. The research results were published in Nature on June 25, 2025.

Traditional genetic code expansion (GCE) techniques rely on stop codon reprogramming, which may disrupt normal cellular translation processes. In contrast, the newly developed RCE technology utilizes pseudouridine (Ψ)-modified RNA codons (ΨCodon) and achieves orthogonal decoding through programmable guide RNA, engineered tRNA, and specific aminoacyl-tRNA synthetase systems. The study demonstrates that this method can accurately recognize ΨGA, ΨAA, and ΨAG codons, efficiently insert various functionalized ncAAs, and preserve the function of the endogenous UGA stop codon.

This technology overcomes the challenge of simultaneously inserting multiple classes of ncAAs in mammalian cells and is compatible with traditional GCE systems, enabling dual-ncAA labeling. The platform's high specificity and low off-target effects were validated through ribosome profiling and proteomics. Chen Peng stated: "RCE technology provides a more precise tool for studying protein function and engineering modifications."

This advancement offers new methods for dynamic regulation of proteins in complex biological systems, drug development, and synthetic biology research. In the future, this technology is expected to be applied in disease mechanism studies and the development of novel biotherapeutics.