title: Recombinase-based conditional and reversible gene regulation via XTR alleles.
abstract: Synthetic biological tools that enable precise regulation of gene function within in vivo systems have enormous potential to discern gene function in diverse physiological settings. Here we report the development and characterization of a synthetic gene switch that, when targeted in the mouse germline, enables conditional inactivation, reports gene expression and allows inducible restoration of the targeted gene. Gene inactivation and reporter expression is achieved through Cre-mediated stable inversion of an integrated gene-trap reporter, whereas inducible gene restoration is afforded by Flp-dependent deletion of the inverted gene trap. We validate our approach by targeting the p53 and Rb genes and establishing cell line and in vivo cancer model systems, to study the impact of p53 or Rb inactivation and restoration. We term this allele system XTR, to denote each of the allelic states and the associated expression patterns of the targeted gene: eXpressed (XTR), Trapped (TR) and Restored (R).
authors.affiliation: Department of Cancer Biology, Abramson Family Cancer Research Institute and Perelman School of Medicine at the University of Pennsylvania, 421 Curie Boulevard, 751 Biomedical Research Building II/III, Philadelphia, Pennsylvania 19004, USA.
authors.forename: Camila
authors.initials: C
authors.lastname: Robles-Oteiza
authors.affiliation: Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology, Cambridge, Massachusetts 02144, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Taylor
authors.affiliation: Department of Cancer Biology, Abramson Family Cancer Research Institute and Perelman School of Medicine at the University of Pennsylvania, 421 Curie Boulevard, 751 Biomedical Research Building II/III, Philadelphia, Pennsylvania 19004, USA.
authors.forename: Travis
authors.initials: T
authors.lastname: Yates
authors.affiliation: Department of Cancer Biology, Abramson Family Cancer Research Institute and Perelman School of Medicine at the University of Pennsylvania, 421 Curie Boulevard, 751 Biomedical Research Building II/III, Philadelphia, Pennsylvania 19004, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Cicchini
authors.affiliation: Department of Cancer Biology, Abramson Family Cancer Research Institute and Perelman School of Medicine at the University of Pennsylvania, 421 Curie Boulevard, 751 Biomedical Research Building II/III, Philadelphia, Pennsylvania 19004, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Lauderback
authors.affiliation: Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology, Cambridge, Massachusetts 02144, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Cashman
authors.affiliation: Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology, Cambridge, Massachusetts 02144, USA.
authors.forename: Aurora A
authors.initials: AA
authors.lastname: Burds
authors.affiliation: Department of Genetics, Department of Pathology, Stanford University School of Medicine, Stanford, California 94305, USA.
authors.forename: Monte M
authors.initials: MM
authors.lastname: Winslow
authors.affiliation: Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology, Cambridge, Massachusetts 02144, USA.|The Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA.
authors.forename: Tyler
authors.initials: T
authors.lastname: Jacks
authors.affiliation: Department of Cancer Biology, Abramson Family Cancer Research Institute and Perelman School of Medicine at the University of Pennsylvania, 421 Curie Boulevard, 751 Biomedical Research Building II/III, Philadelphia, Pennsylvania 19004, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Feldser
mesh_terms: D000483:Alleles; D000818:Animals; D045744:Cell Line, Tumor; D004195:Disease Models, Animal; D018274:Electroporation; D004622:Embryo, Mammalian; D004847:Epithelial Cells; D005347:Fibroblasts; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D017930:Genes, Reporter; D016161:Genes, Retinoblastoma; D005813:Genes, Synthetic / Q000235:genetics*; D016158:Genes, p53; D018095:Germ-Line Mutation; D019426:Integrases / Q000378:metabolism*; D051379:Mice; D009374:Neoplasms, Experimental / Q000235:genetics*; D016133:Polymerase Chain Reaction
chemical_list: C045073:Cre recombinase; D019426:Integrases