title: A genetically encoded biosensor for visualising hypoxia responsesin vivo.
abstract: Cells experience different oxygen concentrations depending on location, organismal developmental stage, and physiological or pathological conditions. Responses to reduced oxygen levels (hypoxia) rely on the conserved hypoxia-inducible factor 1 (HIF-1). Understanding the developmental and tissue-specific responses to changing oxygen levels has been limited by the lack of adequate tools for monitoring HIF-1in vivo.To visualise and analyse HIF-1 dynamics inDrosophila, we used a hypoxia biosensor consisting of GFP fused to the oxygen-dependent degradation domain (ODD) of the HIF-1 homologue Sima. GFP-ODD responds to changing oxygen levels and to genetic manipulations of the hypoxia pathway, reflecting oxygen-dependent regulation of HIF-1 at the single-cell level. Ratiometric imaging of GFP-ODD and a red-fluorescent reference protein reveals tissue-specific differences in the cellular hypoxic status at ambient normoxia. Strikingly, cells in the larval brain show distinct hypoxic states that correlate with the distribution and relative densities of respiratory tubes. We present a set of genetic and image analysis tools that enable new approaches to map hypoxic microenvironments, to probe effects of perturbations on hypoxic signalling, and to identify new regulators of the hypoxia response.
authors.affiliation: Institute of Molecular Life Sciences and Ph.D. program in Molecular Life Sciences, University of Zurich, Zurich CH-8057, Switzerland.
authors.forename: Tvisha
authors.initials: T
authors.lastname: Misra
authors.affiliation: Developmental Neurobiology, IIBCE, Montevideo 116 00, Uruguay.
authors.forename: Martin
authors.initials: M
authors.lastname: Baccino-Calace
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: Felix
authors.initials: F
authors.lastname: Meyenhofer
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Rodriguez-Crespo
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: Hatice
authors.initials: H
authors.lastname: Akarsu
authors.affiliation: LS Instruments AG, Fribourg CH-1700, Switzerland.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Armenta-Calderón
authors.affiliation: Institute of Veterinary Physiology, University of Zurich, Zurich CH-8057, Switzerland.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Gorr
authors.affiliation: Institute of Cell Biology, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland.
authors.forename: Christian
authors.initials: C
authors.lastname: Frei
authors.affiliation: Developmental Neurobiology, IIBCE, Montevideo 116 00, Uruguay.|Zoology Department, Stockholm University, Stockholm 106 91, Sweden.
authors.forename: Rafael
authors.initials: R
authors.lastname: Cantera
authors.affiliation: Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
authors.forename: Boris
authors.initials: B
authors.lastname: Egger
authors.affiliation: Institute of Molecular Life Sciences and Ph.D. program in Molecular Life Sciences, University of Zurich, Zurich CH-8057, Switzerland luschnig@uni-muenster.de.|Institute of Neurobiology, University of Münster, Badestrasse 9, Münster D-48149, Germany.|Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Münster, Münster D-48149, Germany.
authors.forename: Stefan
authors.identifier: http://orcid.org/0000-0002-0634-3368
authors.initials: S
authors.lastname: Luschnig
keywords: Biosensor; Drosophila; HIF-1; Hypoxia; Prolyl hydroxylase; Tracheal system