Abstract
When fused to the ligand binding domain (LBD) of steroid hormone nuclear receptors, site-specific recombinases (SSRs) acquire a ligand-dependent activity. Here, we describe the use of SSR-LBD fusion proteins in an inducible expression system, introduced into cells in a single step. A single transgene contains a constitutively active, bi-directional enhancer/promoter, which directs expression, on one side, of an SSR-LBD fusion protein gene and, on the other, a selectable marker/inducible gene cassette. The selectable marker, the puromycin acetyltransferase (pac) gene, is used for stable genomic integration of the transgene and is flanked by recombination target sites. The inducible gene is not expressed because the pac gene lies between it and the promoter. Activation of the SSR-LBD by a ligand induces recombination and the pac gene is excised. The inducible gene is thus positioned next to the promoter and so is expressed. This describes a ligand-inducible expression strategy that relies on regulated recombination rather than regulated transcription. By inducible expression of diptheria toxin, evidence that this system permits inducible expression of very toxic proteins is presented. The combination of the complete regulatory circuit and inducible gene in one transgene relates expression of the selectable marker gene to expression from the bi-directional enhancer/promoter. We exploit this relationship to show that graded increases in selection pressure can be used to select for clones with different induction properties.
Full Text
The Full Text of this article is available as a PDF (472.7 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Breitman M. L., Clapoff S., Rossant J., Tsui L. C., Glode L. M., Maxwell I. H., Bernstein A. Genetic ablation: targeted expression of a toxin gene causes microphthalmia in transgenic mice. Science. 1987 Dec 11;238(4833):1563–1565. doi: 10.1126/science.3685993. [DOI] [PubMed] [Google Scholar]
- Buchholz F., Ringrose L., Angrand P. O., Rossi F., Stewart A. F. Different thermostabilities of FLP and Cre recombinases: implications for applied site-specific recombination. Nucleic Acids Res. 1996 Nov 1;24(21):4256–4262. doi: 10.1093/nar/24.21.4256. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Church G. M., Gilbert W. Genomic sequencing. Proc Natl Acad Sci U S A. 1984 Apr;81(7):1991–1995. doi: 10.1073/pnas.81.7.1991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cox M. M. The FLP protein of the yeast 2-microns plasmid: expression of a eukaryotic genetic recombination system in Escherichia coli. Proc Natl Acad Sci U S A. 1983 Jul;80(14):4223–4227. doi: 10.1073/pnas.80.14.4223. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Dale E. C., Ow D. W. Intra- and intermolecular site-specific recombination in plant cells mediated by bacteriophage P1 recombinase. Gene. 1990 Jul 2;91(1):79–85. doi: 10.1016/0378-1119(90)90165-n. [DOI] [PubMed] [Google Scholar]
- Danielian P. S., White R., Hoare S. A., Fawell S. E., Parker M. G. Identification of residues in the estrogen receptor that confer differential sensitivity to estrogen and hydroxytamoxifen. Mol Endocrinol. 1993 Feb;7(2):232–240. doi: 10.1210/mend.7.2.8469236. [DOI] [PubMed] [Google Scholar]
- Falco S. C., Li Y., Broach J. R., Botstein D. Genetic properties of chromosomally integrated 2 mu plasmid DNA in yeast. Cell. 1982 Jun;29(2):573–584. doi: 10.1016/0092-8674(82)90173-8. [DOI] [PubMed] [Google Scholar]
- Feil R., Brocard J., Mascrez B., LeMeur M., Metzger D., Chambon P. Ligand-activated site-specific recombination in mice. Proc Natl Acad Sci U S A. 1996 Oct 1;93(20):10887–10890. doi: 10.1073/pnas.93.20.10887. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Golic K. G., Lindquist S. The FLP recombinase of yeast catalyzes site-specific recombination in the Drosophila genome. Cell. 1989 Nov 3;59(3):499–509. doi: 10.1016/0092-8674(89)90033-0. [DOI] [PubMed] [Google Scholar]
- Gossen M., Bujard H. Tight control of gene expression in mammalian cells by tetracycline-responsive promoters. Proc Natl Acad Sci U S A. 1992 Jun 15;89(12):5547–5551. doi: 10.1073/pnas.89.12.5547. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hu M. C., Davidson N. The inducible lac operator-repressor system is functional in mammalian cells. Cell. 1987 Feb 27;48(4):555–566. doi: 10.1016/0092-8674(87)90234-0. [DOI] [PubMed] [Google Scholar]
- Kellendonk C., Tronche F., Monaghan A. P., Angrand P. O., Stewart F., Schütz G. Regulation of Cre recombinase activity by the synthetic steroid RU 486. Nucleic Acids Res. 1996 Apr 15;24(8):1404–1411. doi: 10.1093/nar/24.8.1404. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kilby N. J., Snaith M. R., Murray J. A. Site-specific recombinases: tools for genome engineering. Trends Genet. 1993 Dec;9(12):413–421. doi: 10.1016/0168-9525(93)90104-p. [DOI] [PubMed] [Google Scholar]
- Konsolaki M., Sanicola M., Kozlova T., Liu V., Arcà B., Savakis C., Gelbart W. M., Kafatos F. C. FLP-mediated intermolecular recombination in the cytoplasm of Drosophila embryos. New Biol. 1992 May;4(5):551–557. [PubMed] [Google Scholar]
- Kühn R., Schwenk F., Aguet M., Rajewsky K. Inducible gene targeting in mice. Science. 1995 Sep 8;269(5229):1427–1429. doi: 10.1126/science.7660125. [DOI] [PubMed] [Google Scholar]
- Labow M. A., Baim S. B., Shenk T., Levine A. J. Conversion of the lac repressor into an allosterically regulated transcriptional activator for mammalian cells. Mol Cell Biol. 1990 Jul;10(7):3343–3356. doi: 10.1128/mcb.10.7.3343. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lakso M., Sauer B., Mosinger B., Jr, Lee E. J., Manning R. W., Yu S. H., Mulder K. L., Westphal H. Targeted oncogene activation by site-specific recombination in transgenic mice. Proc Natl Acad Sci U S A. 1992 Jul 15;89(14):6232–6236. doi: 10.1073/pnas.89.14.6232. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Littlewood T. D., Hancock D. C., Danielian P. S., Parker M. G., Evan G. I. A modified oestrogen receptor ligand-binding domain as an improved switch for the regulation of heterologous proteins. Nucleic Acids Res. 1995 May 25;23(10):1686–1690. doi: 10.1093/nar/23.10.1686. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Logie C., Stewart A. F. Ligand-regulated site-specific recombination. Proc Natl Acad Sci U S A. 1995 Jun 20;92(13):5940–5944. doi: 10.1073/pnas.92.13.5940. [DOI] [PMC free article] [PubMed] [Google Scholar]
- No D., Yao T. P., Evans R. M. Ecdysone-inducible gene expression in mammalian cells and transgenic mice. Proc Natl Acad Sci U S A. 1996 Apr 16;93(8):3346–3351. doi: 10.1073/pnas.93.8.3346. [DOI] [PMC free article] [PubMed] [Google Scholar]
- O'Gorman S., Fox D. T., Wahl G. M. Recombinase-mediated gene activation and site-specific integration in mammalian cells. Science. 1991 Mar 15;251(4999):1351–1355. doi: 10.1126/science.1900642. [DOI] [PubMed] [Google Scholar]
- Odell J., Caimi P., Sauer B., Russell S. Site-directed recombination in the genome of transgenic tobacco. Mol Gen Genet. 1990 Sep;223(3):369–378. doi: 10.1007/BF00264442. [DOI] [PubMed] [Google Scholar]
- Orban P. C., Chui D., Marth J. D. Tissue- and site-specific DNA recombination in transgenic mice. Proc Natl Acad Sci U S A. 1992 Aug 1;89(15):6861–6865. doi: 10.1073/pnas.89.15.6861. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rossi F., McNagny K. M., Logie C., Stewart A. F., Graf T. Excision of Ets by an inducible site-specific recombinase causes differentiation of Myb-Ets-transformed hematopoietic progenitors. Curr Biol. 1996 Jul 1;6(7):866–872. doi: 10.1016/s0960-9822(02)00610-3. [DOI] [PubMed] [Google Scholar]
- Sauer B. Functional expression of the cre-lox site-specific recombination system in the yeast Saccharomyces cerevisiae. Mol Cell Biol. 1987 Jun;7(6):2087–2096. doi: 10.1128/mcb.7.6.2087. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sauer B., Henderson N. Site-specific DNA recombination in mammalian cells by the Cre recombinase of bacteriophage P1. Proc Natl Acad Sci U S A. 1988 Jul;85(14):5166–5170. doi: 10.1073/pnas.85.14.5166. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Schwenk F., Kuhn R., Angrand P. O., Rajewsky K., Stewart A. F. Temporally and spatially regulated somatic mutagenesis in mice. Nucleic Acids Res. 1998 Mar 15;26(6):1427–1432. doi: 10.1093/nar/26.6.1427. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sternberg N., Hamilton D. Bacteriophage P1 site-specific recombination. I. Recombination between loxP sites. J Mol Biol. 1981 Aug 25;150(4):467–486. doi: 10.1016/0022-2836(81)90375-2. [DOI] [PubMed] [Google Scholar]
- Yamaizumi M., Mekada E., Uchida T., Okada Y. One molecule of diphtheria toxin fragment A introduced into a cell can kill the cell. Cell. 1978 Sep;15(1):245–250. doi: 10.1016/0092-8674(78)90099-5. [DOI] [PubMed] [Google Scholar]
- Yarranton G. T. Inducible vectors for expression in mammalian cells. Curr Opin Biotechnol. 1992 Oct;3(5):506–511. doi: 10.1016/0958-1669(92)90078-w. [DOI] [PubMed] [Google Scholar]
- Zhang Y., Riesterer C., Ayrall A. M., Sablitzky F., Littlewood T. D., Reth M. Inducible site-directed recombination in mouse embryonic stem cells. Nucleic Acids Res. 1996 Feb 15;24(4):543–548. doi: 10.1093/nar/24.4.543. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de la Luna S., Ortín J. pac gene as efficient dominant marker and reporter gene in mammalian cells. Methods Enzymol. 1992;216:376–385. doi: 10.1016/0076-6879(92)16035-i. [DOI] [PubMed] [Google Scholar]