title: Exploiting position effects and the gypsy retrovirus insulator to engineer precisely expressed transgenes.
abstract: A major obstacle to creating precisely expressed transgenes lies in the epigenetic effects of the host chromatin that surrounds them. Here we present a strategy to overcome this problem, employing a Gal4-inducible luciferase assay to systematically quantify position effects of host chromatin and the ability of insulators to counteract these effects at phiC31 integration loci randomly distributed throughout the Drosophila genome. We identify loci that can be exploited to deliver precise doses of transgene expression to specific tissues. Moreover, we uncover a previously unrecognized property of the gypsy retrovirus insulator to boost gene expression to levels severalfold greater than at most or possibly all un-insulated loci, in every tissue tested. These findings provide the first opportunity to create a battery of transgenes that can be reliably expressed at high levels in virtually any tissue by integration at a single locus, and conversely, to engineer a controlled phenotypic allelic series by exploiting several loci. The generality of our approach makes it adaptable to other model systems to identify and modify loci for optimal transgene expression.
authors.affiliation: Department of Genetics and Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115, USA. mmarkstein@genetics.med.harvard.edu
authors.forename: Michele
authors.initials: M
authors.lastname: Markstein
authors.forename: Chrysoula
authors.initials: C
authors.lastname: Pitsouli
authors.forename: Christians
authors.initials: C
authors.lastname: Villalta
authors.forename: Susan E
authors.initials: SE
authors.lastname: Celniker
authors.forename: Norbert
authors.initials: N
authors.lastname: Perrimon
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001287:Attachment Sites, Microbiological / Q000235:genetics*; D002843:Chromatin / Q000502:physiology*; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D049750:Genome, Insect / Q000235:genetics; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism; D038101:Insulator Elements / Q000235:genetics*; D007814:Larva / Q000378:metabolism; D008969:Molecular Sequence Data; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010957:Plasmids; D051880:Receptors, Notch / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D012190:Retroviridae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D014018:Tissue Distribution; D019076:Transgenes / Q000502:physiology*; D014921:Wings, Animal / Q000502:physiology
chemical_list: C089021:ARP1 protein, S cerevisiae; C488991:AttB protein, Drosophila; D002843:Chromatin; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D018840:HSP70 Heat-Shock Proteins; C499409:Mef2 protein, Drosophila; D018006:Myogenic Regulatory Factors; C497759:N protein, Drosophila; D051880:Receptors, Notch; D029701:Saccharomyces cerevisiae Proteins