[Nucleic Acids-based Elucidation of Molecular Mechanisms of Mutagenesis and Development of Gene Therapy Methods]

DNA preserves and inherits genetic information. 7,8-dihydro-8-oxoguanine (G^O) and abasic sites are some of the most common DNA lesions generated endogenously in living organisms and they induce mutations. The resultant mutations in our DNA cause diseases such as cancers. G^O and abasic sites are known to induce mutations at the positions of the lesions. We revealed G^O induced mutations at points distant from a lesion besides mutations at the lesion site in human cells when WRN helicase or DNA polymerase λ was knocked down. In addition, an abasic site analog, tetrahydrofuran, also induced the same type of mutations and large deletions. Thus, these endogenous DNA damages could induce more diverse mutations than previously thought. Recently, much research toward the development of gene therapy approaches has been carried out to apply gene therapy in a clinical setting. In this study, we found that the usual plasmid DNA with suitable transcription regulatory sequences achieved durably expressed transgenes in mouse liver. In addition, we successfully improved gene-correction efficiency with tailed duplex DNA fragments by introducing a second mismatch. These results give us important information to apply a transgene expression approach and tailed duplexes in a clinical setting.