title: Dual-reporter in vivo imaging of transient and inducible heat-shock promoter activation.
abstract: Gene promoter activity can be studied in vivo by molecular imaging methods using reporter gene technology. Transcription of the reporter and the reported genes occurs simultaneously. However, imaging depends on reporter protein translation, stability, and cellular fate that may differ among the various proteins. A double transgenic mouse strain expressing the firefly luciferase (lucF) and fluorescent mPlum protein under the transcriptional control of the thermo-inducible heat-shock protein (Hspa1b) promoter was generated allowing to follow up the reporter proteins by different and complementary in vivo imaging technologies. These mice were used for in vivo imaging by bioluminescence and epi fluorescence reflectance imaging (BLI & FRI) and as a source of embryonic fibroblast (MEF) for in vitro approaches. LucF, mPlum and endogenous Hsp70 mRNAs were transcribed simultaneously. The increase in mRNA was transient, peaking at 3 h and then returning to the basal level about 6 h after the thermal stimulations. The bioluminescent signal was transient and initiated with a 3 h delay versus mRNA expression. The onset of mPlum fluorescence was more delayed, increasing slowly up to 30 h after heat-shock and remaining for several days. This mouse allows for both bioluminescence imaging (BLI) and fluorescence reflectance imaging (FRI) of Hsp70 promoter activation showing an early and transient lucF activity and a retrospective and persistent mPlum fluorescence. This transgenic mouse will allow following the transient local induction of Hsp-70 promoter beyond its induction time-frame and relate into subsequent dynamic biological effects of the heat-shock response.
authors.affiliation: Laboratoire d'Imagerie Moléculaire et Fonctionnelle (IMF), Université Bordeaux Segalen, CNRS/UMR 5231, Université Bordeaux2, France ; IBIO, Université Bordeaux Segalen, CNRS/UMR 3428, Université Bordeaux 2, France.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Fortin
authors.affiliation: Laboratoire d'Imagerie Moléculaire et Fonctionnelle (IMF), Université Bordeaux Segalen, CNRS/UMR 5231, Université Bordeaux2, France ; IBIO, Université Bordeaux Segalen, CNRS/UMR 3428, Université Bordeaux 2, France.
authors.forename: Coralie
authors.initials: C
authors.lastname: Genevois
authors.affiliation: Laboratoire d'Imagerie Moléculaire et Fonctionnelle (IMF), Université Bordeaux Segalen, CNRS/UMR 5231, Université Bordeaux2, France.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Chapolard
authors.affiliation: Department of Brain Ischemia and Neurodegeneration, Institute for Biomedical Research of Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
authors.forename: Tomàs
authors.initials: T
authors.lastname: Santalucía
authors.affiliation: Department of Brain Ischemia and Neurodegeneration, Institute for Biomedical Research of Barcelona (IIBB), Consejo Superior de Investigaciones Científicas (CSIC), Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Planas
authors.affiliation: Laboratoire d'Imagerie Moléculaire et Fonctionnelle (IMF), Université Bordeaux Segalen, CNRS/UMR 5231, Université Bordeaux2, France ; . Centre de Résonance Magnétique des Systèmes Biologiques (RMSB), Université Bordeaux Segalen, CNRS/UMR 5536, Université Bordeaux 2, France.
authors.forename: Franck
authors.initials: F
authors.lastname: Couillaud
keywords: (280.1415) Biological sensing and sensors; (280.6780) Temperature