The piggyBac-based double-inducible binary vector system: A novel universal platform for studying gene functions and interactions.

Eukaryotic inducible overexpression systems, including Tet-On and mifepristone-inducible systems, have been widely used to study gene functions by reverse genetics. Among the transposon systems reported to date, the piggyBac transposon system is one of the most efficient in cultured mammalian cells. Here, we report a piggyBac-based double-inducible system that combined the advantages of previous systems. To create this system, the trans- and cis-elements of the Tet-On and mifepristone-inducible systems were cloned into a piggyBac-based trans-vector and cis-vector, respectively. The coding regions of two splicing variants of RUNX1, RUNX1a and RUNX1b, were inserted into the cis-vector to test its ability to express foreign genes along with fluorescent marker proteins. Transgenic 293 T cells were established, and the system was tested by inducing expression of foreign genes with DOX and/or mifepristone; GFP and/or mCherry were used as reporter genes. The system efficiently and stringently induced expression of GFP/mCherry and their co-expressed genes without significant mutual interference, as determined by qRT-PCR and Western blot. This piggyBac-based double-inducible system represents a new genetic tool for studying gene functions and interactions in vitro and in vivo in almost all organisms.