Targeted Transgenesis at the HPRT Locus: An Efficient Strategy to Achieve Tightly Controlled in Vivo Conditional Expression With the Tet System

Physiol Genomics. 2009 Apr 10;37(2):140-6. doi: 10.1152/physiolgenomics.90328.2008. Epub 2009 Jan 13.

Abstract

The tet-inducible system has been widely used to achieve conditional gene expression in genetically modified mice. To alleviate the frequent difficulties associated with recovery of relevant transgenic founders, we tested whether a controlled strategy of transgenesis would support reliable cell-specific, doxycycline (Dox)-controlled transgene expression in vivo. Taking advantage of the potent hypoxanthine-aminopterin-thymidine selection strategy and an embryonic stem (ES) cell line supporting efficient germ-line transmission, we used hypoxanthine phosphoribosyltransferase (HPRT) targeting to insert a single copy tet-inducible construct designed to allow both glucocorticoid receptor (GR) and beta-galactosidase (beta-Gal) expression. Conditional, Dox-dependent GR and beta-Gal expression was evidenced in targeted ES cells. Breeding ES-derived single copy transgenic mice with mice bearing appropriate tet transactivators resulted in beta-Gal expression both qualitatively and quantitatively similar to that observed in mice with random integration of the same construct. Interestingly, GR expression in mice was dependent on transgene orientation in the HPRT locus while embryonic stem cell expression was not. Thus, a conditional construct inserted in single copy and in predetermined orientation at the HPRT locus demonstrated a Dox-dependent gene expression phenotype in adult mice suggesting that controlled insertion of tet-inducible constructs at the HPRT locus can provide an efficient alternative strategy to reproducibly generate animal models with tetracycline-induced transgene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Blotting, Western
  • Carrier Proteins / genetics
  • Cell Line
  • Doxycycline / pharmacology
  • Embryonic Stem Cells / cytology
  • Embryonic Stem Cells / drug effects
  • Embryonic Stem Cells / metabolism*
  • Female
  • Gene Expression Regulation / drug effects
  • Gene Knock-In Techniques
  • Genetic Vectors / genetics
  • Humans
  • Hypoxanthine Phosphoribosyltransferase / genetics*
  • Lac Operon / genetics
  • Liver / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Inbred Strains
  • Mice, Transgenic
  • Myocardium / metabolism
  • Receptors, Glucocorticoid / genetics
  • Receptors, Glucocorticoid / metabolism*
  • Staining and Labeling
  • Tetracycline / pharmacology*
  • Transfection
  • beta-Galactosidase / genetics
  • beta-Galactosidase / metabolism

Substances

  • Bacterial Proteins
  • Carrier Proteins
  • Receptors, Glucocorticoid
  • Tet O resistance protein, Bacteria
  • Hypoxanthine Phosphoribosyltransferase
  • beta-Galactosidase
  • Tetracycline
  • Doxycycline