Cell-Specific Control of Mammalian Gene Expression Using DNA Repair Inducible Ribozyme Switches.

The ability to control gene expression is vital for elucidating gene functions and developing next-generation therapeutics. Current techniques are challenged by the lack of cell-specific control designs or immunogenicity risk from foreign proteins. We develop a DNA repair inducible ribozyme switch that enables cell-specific control of gene expression in cells and in vivo. This strategy designs plasmids with a DNA lesion (8-oxoG and O-MeG) site-specifically installed within the ribozyme encoding region, generating active hammerhead ribozyme for mRNA degradation due to transcriptional mutagenesis, whereas DNA repair yields a single-base mismatch in the ribozyme to abrogate its activity. This strategy is demonstrated to allow specific control of gene expression in cancer cells with overexpressed DNA repair enzymes such as MutY DNA glycosylase and O-methylguanine-DNA-methyltransferases. It also shows the capability of conditionally regulating the expression of different proteins for signal reporting and gene editing, enabling DNA repair monitoring and targeted gene therapy in cancer cells. This strategy is demonstrated using the inducible CRISPR/Cas9 system for in vivo editing of oncogenic Polo-like kinase 1 in a mouse model, resulting in significant tumor growth suppression. The DNA repair inducible ribozyme switch may provide a compact system for cell-specific gene expression control toward precise gene therapy.