title: A gene expression system offering multiple levels of regulation: the Dual Drug Control (DDC) system.
abstract: BACKGROUND
  Whether for cell culture studies of protein function, construction of mouse models to enable in vivo analysis of disease epidemiology, or ultimately gene therapy of human diseases, a critical enabling step is the ability to achieve finely controlled regulation of gene expression. Previous efforts to achieve this goal have explored inducible drug regulation of gene expression, and construction of synthetic promoters based on two-hybrid paradigms, among others.
  
  
  RESULTS
  In this report, we describe the combination of dimerizer-regulated two-hybrid and tetracycline regulatory elements in an ordered cascade, placing expression of endpoint reporters under the control of two distinct drugs. In this Dual Drug Control (DDC) system, a first plasmid expresses fusion proteins to DBD and AD, which interact only in the presence of a small molecule dimerizer; a second plasmid encodes a cassette transcriptionally responsive to the first DBD, directing expression of the Tet-OFF protein; and a third plasmid encodes a reporter gene transcriptionally responsive to binding by Tet-OFF. We evaluate the dynamic range and specificity of this system in comparison to other available systems.
  
  
  CONCLUSIONS
  This study demonstrates the feasibility of combining two discrete drug-regulated expression systems in a temporally sequential cascade, without loss of dynamic range of signal induction. The efficient layering of control levels allowed by this combination of elements provides the potential for the generation of complex control circuitry that may advance ability to regulate gene expression in vivo.
authors.affiliation: Department of Molecular Biology and Biotechnology, Russian State Medical University, Moscow, Russia. sudom@inbox.ru
authors.forename: Marina
authors.initials: M
authors.lastname: Sudomoina
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Latypova
authors.forename: Olga O
authors.initials: OO
authors.lastname: Favorova
authors.forename: Erica A
authors.initials: EA
authors.lastname: Golemis
authors.forename: Ilya G
authors.initials: IG
authors.lastname: Serebriiskii
mesh_terms: D000818:Animals; D002460:Cell Line; D019281:Dimerization; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005821:Genetic Techniques; D006801:Humans; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology; D015533:Transcriptional Activation
chemical_list: D011993:Recombinant Fusion Proteins; D013752:Tetracycline