Pseudouridine (Ψ) is the most common chemical modification in RNA. In eukaryotes and archaea, pseudouridine synthases, mainly guided by box H/ACA snoRNAs, convert uridine to Ψ. Ψ stabilizes RNA structure and alters RNA-RNA and RNA-protein interactions, conferring important roles in gene expression. Notably, several Ψ-linked human diseases have been identified over the years. In addition, Ψ has also been extensively used in developing mRNA vaccines. Furthermore, it has been shown that pseudouridylation can be site-specifically directed to modify specific nonsense codons, leading to nonsense suppression. All of these, together with a need to better understand the specific functions of Ψs, have motivated the development of in vitro pseudouridylation assays using purified and reconstituted box H/ACA RNPs. Here, we describe an in vitro system for box H/ACA RNA-guided RNA pseudouridylation using human cell extracts. We show that a half guide RNA (only one hairpin) is just as functionally competent as the full-length guide RNA (two hairpins) in guiding site-specific pseudouridylation in the human cell extracts. This discovery offers the opportunity for direct delivery of a short guide RNA to human cells to promote site-specific nonsense suppression and therefore has potential clinical applications.
Keywords: Box H/ACA RNP; Epitranscriptomics; In vitro editing assay; Pseudouridylation; RNA editing; RNA modification; Therapeutic oligonucleotides.
© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.