title: A time- and dose-dependent STAT1 expression system.
abstract: BACKGROUND
  The signal transducer and activator of transcription (STAT) family of transcription factors mediates a variety of cytokine dependent gene regulations. STAT1 has been mainly characterized by its role in interferon (IFN) type I and II signaling and STAT1 deficiency leads to high susceptibility to several pathogens. For fine-tuned analysis of STAT1 function we established a dimerizer-inducible system for STAT1 expression in vitro and in vivo.
  
  
  RESULTS
  The functionality of the dimerizer-induced STAT1 system is demonstrated in vitro in mouse embryonic fibroblasts and embryonic stem cells. We show that this two-vector based system is highly inducible and does not show any STAT1 expression in the absence of the inducer. Reconstitution of STAT1 deficient cells with inducible STAT1 restores IFNgamma-mediated gene induction, antiviral responses and STAT1 activation remains dependent on cytokine stimulation. STAT1 expression is induced rapidly upon addition of dimerizer and expression levels can be regulated in a dose-dependent manner. Furthermore we show that in transgenic mice STAT1 can be induced upon stimulation with the dimerizer, although only at low levels.
  
  
  CONCLUSIONS
  These results prove that the dimerizer-induced system is a powerful tool for STAT1 analysis in vitro and provide evidence that the system is suitable for the use in transgenic mice. To our knowledge this is the first report for inducible STAT1 expression in a time- and dose-dependent manner.
authors.affiliation: Institute of Animal Breeding and Genetics, Veterinary University of Vienna, Veterinärplatz 1, 1210 Vienna, Austria. nicole.leitner@i122server.vu-wien.ac.at
authors.forename: Nicole R
authors.initials: NR
authors.lastname: Leitner
authors.forename: Birgit
authors.initials: B
authors.lastname: Strobl
authors.forename: Marion
authors.initials: M
authors.lastname: Bokor
authors.forename: Ronald
authors.initials: R
authors.lastname: Painz
authors.forename: Thomas
authors.initials: T
authors.lastname: Kolbe
authors.forename: Thomas
authors.initials: T
authors.lastname: Rülicke
authors.forename: Mathias
authors.initials: M
authors.lastname: Müller
authors.forename: Marina
authors.initials: M
authors.lastname: Karaghiosoff
mesh_terms: D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D015202:Protein Engineering / Q000379:methods*; D011994:Recombinant Proteins / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000378:metabolism*; D022021:Tacrolimus Binding Proteins / Q000008:administration & dosage / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D014162:Transfection / Q000379:methods*
chemical_list: D011994:Recombinant Proteins; D050794:STAT1 Transcription Factor; C494080:Stat1 protein, mouse; D022021:Tacrolimus Binding Proteins