Gene knockdown in the mouse through RNAi.

RNA interference (RNAi)-mediated gene knockdown has developed into a routine method to assess gene function in cultured mammalian cells in a fast and easy manner. For the use of RNAi in mice, short hairpin (sh) RNAs expressed from transgenic vectors are a fast alternative to conventional knockout approaches. We describe our strategy to elicit body-wide, cell type-specific, or inducible gene silencing in mice by control of shRNA expression through Cre recombinase or doxycycline. For reproducible expression of shRNAs, vectors are placed into the Rosa26 locus of ES cells by recombinase-mediated cassette exchange and transmitted through the germ line of chimeric mice. The site specific insertion of single copy shRNA vectors allows to expedite and reproducible production of knockdown mice and provides a simple approach to assess gene function in vivo.