Specific micro RNA-regulated TetR-KRAB transcriptional control of transgene expression in viral vector-transduced cells.

Precise control of transgene expression in a tissue-specific and temporally regulated manner is desirable for many basic and applied investigations gene therapy applications. This is important to regulate dose of transgene products and minimize unwanted effects. Previously described methods have employed tissue specific promoters, miRNA-based transgene silencing or tetR-KRAB-mediated suppression of transgene promoters. To improve on versatility of transgene expression control, we have developed expression systems that use combinations of a tetR-KRAB artificial transgene-repressor, endogenous miRNA silencing machinery and tissue specific promoters. Precise control of transgene expression was demonstrated in liver-, macrophage- and muscle-derived cells. Efficiency was also demonstrated in vivo in murine muscle. This multicomponent and modular regulatory system provides a robust and easily adaptable method for achieving regulated transgene expression in different tissue types. The improved precision of regulation will be useful for many gene therapy applications requiring specific spatiotemporal transgene regulation.