Efficient transposition of the piggyBac (PB) transposon in mammalian cells and mice

Key findings

Ding et al. demonstrated that the piggyBac (PB) transposon from Trichoplusia ni efficiently transposes in mammalian systems. Cotransfection of PB donor and PBase helper plasmids in human 293 cells produced neomycin-resistant clones at 10-fold higher rates than donor alone. In mouse ES cells, co-transfection with Act-PBase generated drug-resistant clones 50-fold above background, confirming robust transposition activity across mammalian cell lines.

PB insertions occurred almost exclusively at TTAA target sites, confirmed by inverse PCR sequencing of junction fragments from multiple independent clones. The transposon carried multiple marker genes (neomycin resistance, RFP, tyrosinase) and permitted expression at diverse genomic locations. Insertions preferentially targeted transcription units with no chromosomal regional bias, enabling broad utility as a versatile insertional mutagenesis tool.

In mouse germline transgenesis, pronuclear coinjection of PB[Act-RFP] donor with Act-PBase helper achieved a 34.8% (62/184) founder rate versus 10.4% (10/96) without transposase. Integrated transposons transmitted stably through the germline, with 15 of 16 progeny retaining the transgene. PB elements excised precisely from original insertion sites and reinserted at diverse genomic loci, establishing piggyBac as an efficient vertebrate transgenesis system.