Transcriptionally regulated and non-toxic delivery of the hyperactive Sleeping Beauty Transposase

The Sleeping Beauty (SB) transposase and, in particular, its hyperactive variant SB100X raised increasing interest for gene therapy application, genomic modification and, more recently, iPS reprogramming. The documented cytotoxicity of the transposase, when constitutively expressed by a gamma retroviral vector (iRV) has been circumvented by transduction of SB100X mRNA packaged into retrovirus particles (Galla et al. NAR 2011, Vol. 39, No. 16). In this study, we developed an alternative, safe and efficient transposase delivery system based on the tetracycline-ON regulatory system and on integrase defective lentiviral vectors (IDLV). The un-integrated and transcriptionally regulated expression of SB100X may become crucial in gene therapy and in iPS reprogramming, where permanent transposase expression could result in uncontrollable transposition. We generated two IDLV vectors, one carrying the rtTA2-M2 transactivator and the second bearing the tightly regulated, drug-inducible SB100X expression cassette.