Factors involved in regulation of the RT7 promoter in a male germ cell-derived in vitro transcription system.

We recently cloned and characterized a rat male germ cell-specific gene, RT7. The RT7 promoter contains a TATA box as well as sequences with homology to binding sites for a number of transcription factors. To investigate the regulation of the RT7 promoter we developed an active in vitro transcription system derived from rat seminiferous epithelium, which, in contrast to total testis, consists mostly of male germ cells. Also, DNase I footprinting analysis and gel retardation experiments were performed to analyze RT7 promoter-protein interaction. The experiments demonstrate that nuclear extracts prepared from rat male germ cells support in vitro transcription and that the RT7 promoter is positively regulated by a testis-specific transcription factor, TTF-D, by a factor similar to the transcription factor CREB, and by a nuclear factor that binds immediately upstream of the RT7 transcription start site.