The Sleeping Beauty (SB) transposon is a promising technology platform for gene transfer in vertebrates; however, its efficiency of gene insertion can be a bottleneck in primary cell types. A large-scale genetic screen in mammalian cells yielded a hyperactive transposase (SB100X) with approximately 100-fold enhancement in efficiency when compared to the first-generation transposase. SB100X supported 35-50% stable gene transfer in human CD34(+) cells enriched in hematopoietic stem or progenitor cells. Transplantation of gene-marked CD34(+) cells in immunodeficient mice resulted in long-term engraftment and hematopoietic reconstitution. In addition, SB100X supported sustained (>1 year) expression of physiological levels of factor IX upon transposition in the mouse liver in vivo. Finally, SB100X reproducibly resulted in 45% stable transgenesis frequencies by pronuclear microinjection into mouse zygotes. The newly developed transposase yields unprecedented stable gene transfer efficiencies following nonviral gene delivery that compare favorably to stable transduction efficiencies with integrating viral vectors and is expected to facilitate widespread applications in functional genomics and gene therapy.

No abstract

We recently reported the cloning of a mitogen-inducible prostaglandin synthase gene, TIS10/PGS2. In addition to growth factors and tumor promoters, the v-src oncogene induces TIS10/PGS2 expression in 3T3 cells. Deletion analysis, using luciferase reporters, identifies a region between -80 and -40 nucleotides 5' of the TIS10/PGS2 transcription start site that mediates pp6Wvsrc induction in 3T3 cells. This region contains the sequence CGTCACGTG, which includes overlapping ATF/CRE (CGTCA) and E-box (CACGTG) sequences. Gel shift-oligonucleotide competition experiments with nuclear extracts from cells stably transfected with a temperature-sensitive v-src gene demonstrate that the CGTCACGTG sequence can bind proteins at both the ATF/CRE and E-box sequences. Dominant-negative CREB and Myc proteins that bind DNA, but do not transactivate, block v-src induction of a luciferase reporter driven by the first 80 nucleotides of the TIS10/PGS2 promoter. Mutational analysis distinguishes which TIS10/PGS2 cis-acting element mediates pp60v' induction. E-box mutation has no effect on the fold induction in response to pp60VW . In contrast, ATF/CRE mutation attenuates the pp60V' response. Antibody supershift and methylation interference experiments demonstrate that CREB and at least one other ATF transcription factor in these extracts bind to the TIS1O/PGS2 ATF/CRE element. Expression of a dominant-negative ras gene also blocks TIS10/PGS2 induction by v-src. Our data suggest that Ras mediates pp60V' activation of an ATF transcription factor, leading to induced TIS10/PGS2 expression via the ATF/CRE element of the TIS10/PGS2 promoter. This is the first description of v-src activation of gene expression via an ATF/CRE element.

No abstract