In vivo transposition of Minos, a Drosophila mobile element, in mammalian tissues

Transposable elements have been used widely in the past 20 years for gene t ransfer and insertional mutagenesis in Drosophila. Transposon-based technol ogy for gene manipulation and genomic analysis currently is being adopted f or vertebrates. We tested the ability of Minos, a DNA transposon from Droso phila hydei, to transpose in mouse tissues. Two transgenic mouse lines were crossed, one expressing Minos transposase in lymphocytes under the control of the CD2 promoter/locus control region and another carrying a nonautonom ous Minos transposon. Only mice containing both transgenes show excision of the transposon and transposition into new chromosomal sites in thymus and spleen cells. In addition, expression of Minos transposase in embryonic fib roblast cell lines derived from a transposon-carrying transgenic mouse resu lted in excision of the transposon. These results are a first step toward a reversible insertional mutagenesis system in the mouse, opening the way to develop powerful technologies for functional genomic analysis in mammals.