Single-base conversion of mammalian genes by an RNA-DNA oligonucleotide

An oligonucleotide composed of a contiguous stretch of RNA and DNA residues has been developed to facilitate correction of single-base mutations of episomal and chromosomal targets in mammalian cells. Design of the oligonucleotide exploited the highly recombinogenic RNA-DNA hybrids and featured hairpin capped ends avoiding destruction by cellular helicases or exonucleases. The RNA-DMA oligonucleotide (RDO) was shown to cause a site-specific chromosomal correction in several genes and to induce a sequence-specific mutation in vivo by intravenous injection. Moreover, a permanent and stable gene correction by the RDO was demonstrated by clonal analysis at the level of genomic sequence, protein and phenotypic change. The RDO might hold promise as a therapeutic method for the treatment of genetic diseases. However, the frequency of gene correction varies among different cells and individual experiments. Cellular activities such as recombination and repair may be important for gene conversion by the RDO. As this technology is more widely utilized in the scientific community, it will be important to understand the mechanism and to optimize the design of the RDO to improve its efficiency and its general applicability.