[Molecular genetic characterization of the regulatory region of the Xist gene in the common vole Microtus rossiaemeridionalis].

Two conserved regions were discovered as a result of interspecific comparison of the 5'-region of the Xist gene, which is the key gene in the process of X-chromosome inactivation in mammalian females. The first region corresponds to the minimal promoter, and the second spans between -480 bp and -400 bp from the start of Xist transcription. Footprinting experiments revealed protected regions corresponding to the potential binding sites for TBP, SP1, API, SRY, ER, and some other transcription factors. They also demonstrated the interaction with the minimal promoter of the human recombinant transcription factor SP1 in vitro and of the transcription factor CTCF in vivo. Experiments with reporter constructs showed that repressors of Xist transcription were located between -100 bp and -200 bp and between -300 bp and -400 bp and activators of Xist transcription were located between -200 bp and -300 bp and between -400 bp and -500 bp.