title: Quantitative imaging of gene induction in living animals.
abstract: Methods to repeatedly, non-invasively, and quantitatively image gene expression in living animals are rapidly emerging and should fundamentally change studies of gene expression in vivo. We previously developed assays utilizing positron emission tomography (PET) to image reporter gene expression. In this paper we: (1) describe a new bi-directional, tetracycline-inducible system that can be used to pharmacologically induce target gene expression and to quantitatively image induced expression by using a PET reporter gene; (2) demonstrate the potential of this system in transient and stable cell transfection assays; and (3) demonstrate the ability to repetitively and quantitatively image tetracycline and tetracycline analog induction of gene expression in living animals. We utilize the dopamine type-2 receptor (D(2)R) and the mutant herpes-simplex virus type 1 thymidine kinase (HSV1-sr39tk) reporter genes to validate this system. We utilize microPET technology to show that quantitative tomographic imaging of gene induction is possible. We find a high correlation (r(2) = 0.98) between 'target' and reporter gene expression. This work establishes a new technique for imaging time-dependent variation of gene expression both from vectors with inducible promoters and in transgenic animals in which pharmacologic induction of gene expression must be monitored. These techniques may be applied both in gene therapy and for the study of gene expression in transgenic animals.
authors.affiliation: The Crump Institute for Molecular Imaging, UCLA School of Medicine, 90095-1770, USA.
authors.forename: X
authors.initials: X
authors.lastname: Sun
authors.forename: A J
authors.initials: AJ
authors.lastname: Annala
authors.forename: S S
authors.initials: SS
authors.lastname: Yaghoubi
authors.forename: J R
authors.initials: JR
authors.lastname: Barrio
authors.forename: K N
authors.initials: KN
authors.lastname: Nguyen
authors.forename: T
authors.initials: T
authors.lastname: Toyokuni
authors.forename: N
authors.initials: N
authors.lastname: Satyamurthy
authors.forename: M
authors.initials: M
authors.lastname: Namavari
authors.forename: M E
authors.initials: ME
authors.lastname: Phelps
authors.forename: H R
authors.initials: HR
authors.lastname: Herschman
authors.forename: S S
authors.initials: SS
authors.lastname: Gambhir
mesh_terms: D000818:Animals; D015870:Gene Expression / Q000187:drug effects; D017930:Genes, Reporter; D005818:Genetic Engineering; D015316:Genetic Therapy; D006367:HeLa Cells; D018259:Herpesvirus 1, Human / Q000201:enzymology*; D006801:Humans; D008156:Luciferases / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D008822:Mice, Transgenic; D009368:Neoplasm Transplantation; D011401:Promoter Regions, Genetic; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D013752:Tetracycline / Q000494:pharmacology; D013937:Thymidine Kinase / Q000235:genetics*; D013997:Time Factors; D014055:Tomography, Emission-Computed / Q000379:methods*; D014162:Transfection / Q000379:methods*; D014407:Tumor Cells, Cultured; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D017448:Receptors, Dopamine D2; D008156:Luciferases; D013937:Thymidine Kinase; D001616:beta-Galactosidase; D013752:Tetracycline