Transactivation of Hox gene expression in a VP16-dependent binary transgenic mouse system

Normal proliferation and differentiation of Hoxc-8 transgenic chondrocytes in vitro

“…Real-time quantitative PCR was performed. As shown in Figure 8, Hoxc-8 expression is elevated in Hoxc-8 transgenic mice, as expected [23]. Differences also exist between controls and transgenics in expression levels for several genes involved in cartilage development.…”

“…Essentially similar proportions of cells in S phase were found in all cultures (Figure 7, Panel B). This was regardless of levels of expression of the Hoxc-8 transgene (Figure 7, Panel B) which increases with increasing transgene dosage [1,23]. These data indicate that, after appropriate time in culture, transgenic chondrocytes were able to proliferate normally, at least over the 24 hours duration of the assay.…”

“…Briefly, Hoxc-8 expressing mice are generated in a binary transgenic mouse system [44] by crossing a transactivator strain (harboring a transgene in which expression of the transcriptional transactivator VP16 is under control of the Hoxc-8 promoter; [45]) to a transresponder strain (that carries as a transgene the Hoxc-8 cDNA linked to the ICP4 immediate early gene promoter, which is silent in mice in the absence of VP16; [45,46]). Upon combination of both transgenes, the Hoxc-8 transresponder transgene is activated, and Hoxc-8 becomes overexpressed [23]. This system also allows the generation of transgenic mice with increased gene dosage by superimposition of transgene loci to homozygosity [23,44].…”

“…Upon combination of both transgenes, the Hoxc-8 transresponder transgene is activated, and Hoxc-8 becomes overexpressed [23]. This system also allows the generation of transgenic mice with increased gene dosage by superimposition of transgene loci to homozygosity [23,44]. For the studies reported here, we used the T239 transactivator and the IE-c8-254 transresponder strains.…”

“…Maintenance and genotyping of transgenic mice was done as described before [1,23]. Unless otherwise noted, cells and samples were obtained from animals hemizygous for both transgenes.…”