Related Experiment Video
Updated: Aug 29, 2025

In Vitro Selection of Engineered Transcriptional Repressors for Targeted Epigenetic Silencing
Published on: May 5, 2023
A modular XNAzyme cleaves long, structured RNAs under physiological conditions and enables allele-specific gene
Alexander I Taylor1, Christopher J K Wan2, Maria J Donde3
1Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), University of Cambridge, Cambridge, UK. ait29@cam.ac.uk.
Abstract:
Nucleic-acid catalysts (ribozymes, DNA- and XNAzymes) cleave target (m)RNAs with high specificity but have shown limited efficacy in clinical applications. Here we report on the in vitro evolution and engineering of a highly specific modular RNA endonuclease XNAzyme, FR6_1, composed of 2'-deoxy-2'-fluoro-β-D-arabino nucleic acid (FANA). FR6_1 overcomes the activity limitations of previous DNA- and XNAzymes and can be retargeted to cleave highly structured full-length (>5 kb) BRAF and KRAS mRNAs at physiological Mg2+ concentrations with allelic selectivity for tumour-associated (BRAF V600E and KRAS G12D) mutations. Phosphorothioate-FANA modification enhances FR6_1 biostability and enables rapid KRAS mRNA knockdown in cultured human adenocarcinoma cells with a G12D-allele-specific component provided by in vivo XNAzyme cleavage activity. These results provide a starting point for the development of improved gene-silencing agents based on FANA or other XNA chemistries.
Related Concept Videos
siRNA - Small Interfering RNAs
In the cytoplasm, siRNA is processed from a double-stranded RNA, which comes from either endogenous DNA transcription or exogenous sources like a virus. This double-stranded RNA is then cleaved by the...
Experimental RNAi
RNA Interference
This process occurs naturally in cells, often through the activity of genomically-encoded microRNAs. Researchers can take advantage of this mechanism by introducing synthetic RNAs to deactivate specific genes for research or therapeutic purposes. For example, RNAi could be used...
MicroRNAs
Types of RNA
RNA Performs Diverse...
mRNA Stability and Gene Expression
Cis-acting Elements involved in mRNA stability

