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Biol Open. 2017 Feb 15;6(2):296-304. doi: 10.1242/bio.018226.

A genetically encoded biosensor for visualising hypoxia responses in vivo.

Author information

1
Institute of Molecular Life Sciences and Ph.D. program in Molecular Life Sciences, University of Zurich, Zurich CH-8057, Switzerland.
2
Developmental Neurobiology, IIBCE, Montevideo 116 00, Uruguay.
3
Department of Biology, University of Fribourg, Fribourg CH-1700, Switzerland.
4
LS Instruments AG, Fribourg CH-1700, Switzerland.
5
Institute of Veterinary Physiology, University of Zurich, Zurich CH-8057, Switzerland.
6
Institute of Cell Biology, Swiss Federal Institute of Technology, Zurich CH-8093, Switzerland.
7
Zoology Department, Stockholm University, Stockholm 106 91, Sweden.
8
Institute of Molecular Life Sciences and Ph.D. program in Molecular Life Sciences, University of Zurich, Zurich CH-8057, Switzerland luschnig@uni-muenster.de.
9
Institute of Neurobiology, University of Münster, Badestrasse 9, Münster D-48149, Germany.
10
Cells-in-Motion Cluster of Excellence (EXC 1003-CiM), University of Münster, Münster D-48149, Germany.

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-1 in vivo. To visualise and analyse HIF-1 dynamics in Drosophila, 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.

KEYWORDS:

Biosensor; Drosophila; HIF-1; Hypoxia; Prolyl hydroxylase; Tracheal system

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