Generation of reversible Rb-knockdown mice

This study describes the generation of reversible Rb-knockdown mice using Tet-off system coupled with Rb-deficient mice currently available. Mice expressing pRB conditionally in Rb−/− background were generated by crossings PhCMV-tTA/TRE-Rb transgenic mice with conventional Rb+/− mice. Transgenic Rb was tightly controlled with reversibility and biologically effective as exemplified by cyclin E expression in a doxycycline-dependent manner in mouse embryonic fibroblasts. However, its ectopic expression was not sufficient to rescue the phenotypes of Rb−/− embryos at organismal level, suggesting the requirement of more sophisticated regulation of pRB. With all, these results demonstrate that our experimental strategy can be an alternative way to convert classical gene-disrupted mice into reversible conditional ones.